chore: fix example of err msg by re-running sample

the following code was okay in the last release
```
toml::format_error("[test]", v, "test", {"hint1", "hint2"})
```
but was not okay in the current master. This commit fixes this.

cons: By this, the number of values to show is limited upto 3.

.circleci/config.yml

@@ -0,0 +1,59 @@
+version: 2.1
+
+jobs:
+  test_suite:
+    environment:
+      - GOPATH: /home/circleci/go
+    docker:
+      - image: circleci/golang:1.9
+    steps:
+      - checkout
+      - run:
+          command: |
+              g++ --version
+              cd tests/
+              g++ -std=c++11 -O2 -Wall -Wextra -Werror -I../ check_toml_test.cpp -o check_toml_test
+              go get github.com/BurntSushi/toml-test
+              $GOPATH/bin/toml-test ./check_toml_test
+  output_result:
+    docker:
+      - image: circleci/buildpack-deps:bionic
+    steps:
+      - checkout
+      - run:
+          command: |
+              g++ --version
+              cd tests/
+              g++ -std=c++11 -O2 -Wall -Wextra -Werror -I../ check.cpp -o check
+              git clone https://github.com/BurntSushi/toml-test.git
+              cp check toml-test/tests/invalid
+              cp check toml-test/tests/valid
+              cd toml-test/tests/invalid
+              for f in $(ls ./*.toml);
+                do echo "==> ${f}";
+                cat ${f};
+                echo "---------------------------------------";
+                ./check ${f} invalid;
+                if [ $? -ne 0 ] ; then
+                  exit 1
+                fi
+                echo "=======================================";
+              done
+              cd ../valid
+              for f in $(ls ./*.toml);
+                do echo "==> ${f}";
+                cat ${f};
+                echo "---------------------------------------";
+                ./check ${f} valid;
+                if [ $? -ne 0 ] ; then
+                  exit 1
+                fi
+                echo "=======================================";
+              done
+
+workflows:
+  version: 2.1
+  test:
+    jobs:
+      - test_suite
+      - output_result

.travis.yml

@@ -12,8 +12,39 @@ matrix:
         - ubuntu-toolchain-r-test
         packages:
         - g++-5
-        - build-essential
-        - cmake
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: gcc
+    env: COMPILER="g++-6"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        packages:
+        - g++-6
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: gcc
+    env: COMPILER="g++-7"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        packages:
+        - g++-7
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: gcc
+    env: COMPILER="g++-8"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        packages:
+        - g++-8
         - libboost-all-dev
   - os: linux
     language: cpp
@@ -26,8 +57,66 @@ matrix:
         - llvm-toolchain-precise-3.7
         packages:
         - clang-3.7
-        - build-essential
-        - cmake
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-4.0"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        - llvm-toolchain-trusty-4.0
+        packages:
+        - clang-4.0
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-5.0"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        - llvm-toolchain-trusty-5.0
+        packages:
+        - clang-5.0
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-6.0"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        - llvm-toolchain-trusty-6.0
+        packages:
+        - clang-6.0
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-7"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        - llvm-toolchain-trusty-7
+        packages:
+        - clang-7
+        - libboost-all-dev
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-8"
+    addons:
+      apt:
+        sources:
+        - ubuntu-toolchain-r-test
+        - llvm-toolchain-trusty-8
+        packages:
+        - clang-8
         - libboost-all-dev
   - os: osx
     language: cpp

PROPOSAL.md

@@ -1,59 +0,0 @@
-
-### encoding user's data
-
-You can encode your data to toml format.
-
-```cpp
-const toml::value integer(1);
-const toml::value array{3.1, 3.14, 3.141, 3.1415};
-const toml::value table{{"answer", 42}, {"pi", 3.14}, {"string", "foobar"}};
-
-std::cout << toml::format("integer", integer) << std::endl;
-std::cout << toml::format("array",   array)   << std::endl;
-std::cout << toml::format("table",   table)   << std::endl;
-```
-
-this program will output as below.
-
-```toml
-integer = 1
-array = [3.1, 3.14, 3.141, 3.1415]
-[table]
-answer = 42
-pi = 3.14
-string = "foobar"
-```
-
-Without key name, you can make string formatted as toml.
-
-```cpp
-const std::string integer_ = toml::format(integer); // "1"
-const std::string array_   = toml::format(array);   // "[3.1, 3.14, 3.141, 3.1415]"
-const std::string table_   = toml::format(table);   // "answer = 42\npi=3.14\nstring=foobar"
-```
-
-### inlinize
-
-You can make `toml::Table` inline.
-
-```cpp
-const toml::value table{{"answer", 42}, {"pi", 3.14}, {"string", "foobar"}};
-// if the inline-table format length is less than 80, the table will be inlined
-std::cout << toml::format("table", table, toml::make_inline(80)) << std::endl;
-// In any case, the table will be inlined.
-std::cout << toml::format("table", table, toml::forceinline) << std::endl;
-```
-
-```toml
-table = {answer = 42, pi = 3.14, string = "foobar"}
-```
-
-And there are some stream manipulators for toml format.
-
-```cpp
-const toml::value table{{"answer", 42}, {"pi", 3.14}, {"string", "foobar"}};
-// if the inline-table format length is less than 80, the table will be inlined
-std::cout << toml::make_inline(80) << table << std::endl;
-// In any case, the table will be inlined.
-std::cout << toml::forceinline << table << std::endl;
-```

README.md

@@ -1,20 +1,53 @@
 toml11
 ======
 
-[![Build Status](https://travis-ci.org/ToruNiina/toml11.svg?branch=master)](https://travis-ci.org/ToruNiina/toml11)
-[![Build status](https://ci.appveyor.com/api/projects/status/m2n08a926asvg5mg?svg=true)](https://ci.appveyor.com/project/ToruNiina/toml11)
-[![MIT License](http://img.shields.io/badge/license-MIT-blue.svg?style=flat)](LICENSE)
+[![Build Status on TravisCI](https://travis-ci.org/ToruNiina/toml11.svg?branch=master)](https://travis-ci.org/ToruNiina/toml11)
+[![Build status on Appveyor](https://ci.appveyor.com/api/projects/status/m2n08a926asvg5mg/branch/master?svg=true)](https://ci.appveyor.com/project/ToruNiina/toml11/branch/master)
+[![Build status on CircleCI](https://circleci.com/gh/ToruNiina/toml11/tree/master.svg?style=svg)](https://circleci.com/gh/ToruNiina/toml11/tree/master)
+[![Version](https://img.shields.io/github/release/ToruNiina/toml11.svg?style=flat)](https://github.com/ToruNiina/toml11/releases)
+[![License](https://img.shields.io/github/license/ToruNiina/toml11.svg?style=flat)](LICENSE)
 [![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.1209136.svg)](https://doi.org/10.5281/zenodo.1209136)
 
-c++11 header-only toml parser depending only on c++ standard library.
+toml11 is a C++11 header-only toml parser/encoder depending only on C++ standard library.
 
-compatible to the latest version of [TOML v0.5.0](https://github.com/toml-lang/toml/blob/master/versions/en/toml-v0.5.0.md) after version 2.0.0.
+compatible to the latest version of
+[TOML v0.5.0](https://github.com/toml-lang/toml/blob/master/versions/en/toml-v0.5.0.md)
+after version 2.0.0.
 
-Are you looking for pre-C++11 compatible toml parser? Try [Boost.toml](https://github.com/ToruNiina/Boost.toml)! It has almost the same functionality as this library and works with C++98 & Boost.
+It passes [the language agnostic test suite for TOML parsers by BurntSushi](https://github.com/BurntSushi/toml-test).
+Not only the test suite itself, a TOML reader/encoder also runs on [CircleCI](https://circleci.com/gh/ToruNiina/toml11).
+You can see the error messages about invalid files and serialization results of valid files at
+[CircleCI](https://circleci.com/gh/ToruNiina/toml11).
 
-## How to use
+## Table of Contents
 
-## Installation
+- [Integration](#integration)
+- [Decoding a toml file](#decoding-a-toml-file)
+  - [In the case of syntax error](#in-the-case-of-syntax-error)
+- [Getting a toml value](#getting-a-toml-value)
+  - [In the case of type error](#in-the-case-of-type-error)
+- [Getting an array](#getting-an-array)
+- [Getting a table](#getting-a-table)
+  - [Dotted keys](#dotted-keys)
+- [Getting an array of tables](#getting-an-array-of-tables)
+- [Cost of conversion](#cost-of-conversion)
+- [Getting datetime and its variants](#getting-datetime-and-its-variants)
+- [Getting with a fallback](#getting-with-a-fallback)
+- [Expecting conversion](#expecting-conversion)
+- [Finding a value from a table](#finding-a-value-from-a-table)
+- [Checking value type](#checking-value-type)
+- [Visiting a toml::value](#visiting-a-tomlvalue)
+- [TOML literal](#toml-literal)
+- [Conversion between toml value and arbitrary types](#conversion-between-toml-value-and-arbitrary-types)
+- [Invalid UTF-8 Codepoints](#invalid-utf-8-codepoints)
+- [Formatting user-defined error messages](#formatting-user-defined-error-messages)
+- [Serializing TOML data](#serializing-toml-data)
+- [Underlying types](#underlying-types)
+- [Running Tests](#running-tests)
+- [Contributors](#contributors)
+- [Licensing Terms](#licensing-terms)
+
+## Integration
 
 Just include the file after adding it to the include path.
 
@@ -29,32 +62,40 @@ int main()
 }
 ```
 
-### Decoding toml file
+## Decoding a toml file
 
-The only thing you have to do is to pass a filename to the `toml::parse` function.
+To parse a toml file, the only thing you have to do is
+to pass a filename to the `toml::parse` function.
 
 ```cpp
 const std::string fname("sample.toml");
 const toml::table data = toml::parse(fname);
 ```
 
-In the case of file open error, it will throw `std::runtime_error`.
+If it encounters a file open error, it will throw `std::runtime_error`.
 
-You can also pass a `stream` to the  `toml::parse` function after checking the status.
+You can also pass a `std::istream` to the  `toml::parse` function.
+To show a filename in an error message, it is recommended to pass the filename
+with the stream.
 
 ```cpp
-std::ifstream ifs("sample.toml");
+std::ifstream ifs("sample.toml", std::ios_base::binary);
 assert(ifs.good());
-const auto data = toml::parse(ifs /*, "filename" (optional)*/);
+const auto data = toml::parse(ifs, /*optional*/ "sample.toml");
 ```
 
-To show a better error message, it is recommended to pass a filename with `istream`. See also [in the case of syntax error](#in-the-case-of-syntax-error) and [passing invalid type to toml::get](#passing-invalid-type-to-tomlget).
+Note that on Windows, if a file is opened in text-mode, CRLF ("\r\n") will
+automatically be converted to LF ("\n") and this causes inconsistency between
+file size and the contents that would be read. This causes weird error.
+To use a file stream with `toml::parse` on Windows, don't forget to open it
+in binary mode.
 
 ### In the case of syntax error
 
 If there is a syntax error in a toml file, `toml::parse` will throw `toml::syntax_error`.
 
-toml11 now has clean and informative error messages inspired by Rust and it looks like the following (comment after hash sign are actually not shown).
+toml11 has clean and informative error messages inspired by Rust and
+it looks like the following.
 
 ```console
 terminate called after throwing an instance of 'toml::syntax_error'
@@ -64,7 +105,8 @@ terminate called after throwing an instance of 'toml::syntax_error'
    |        ^------ expected newline, but got '='.        # error reason
 ```
 
-If you (mistakenly) duplicate tables and got an error, you may want to see where the other is. toml11 shows both at the same time.
+If you (mistakenly) duplicate tables and got an error, it is helpful to see
+where they are. toml11 shows both at the same time like the following.
 
 ```console
 terminate called after throwing an instance of 'toml::syntax_error'
@@ -77,13 +119,17 @@ terminate called after throwing an instance of 'toml::syntax_error'
    | ~~~~~~~ table defined twice
 ```
 
-Since the error message generation is generally a difficult task, the current status is not ideal. toml11 needs your help. If you encounter a weird error message, please let us know and contribute to improve the quality!
+Since the error message generation is generally a difficult task, the current
+status is not ideal. If you encounter a weird error message, please let us know
+and contribute to improve the quality!
 
-### Getting a toml value
+## Getting a toml value
 
-After parsing successfully, you can obtain the values from the result of `toml::parse` (here, `data`) using `toml::get` function.
+After parsing successfully, you can obtain the values from the result of
+`toml::parse` using `toml::get` function.
 
 ```toml
+# sample.toml
 answer  = 42
 pi      = 3.14
 numbers = [1,2,3]
@@ -93,6 +139,7 @@ key = "value"
 ```
 
 ``` cpp
+const auto data      = toml::parse("sample.toml");
 const auto answer    = toml::get<std::int64_t    >(data.at("answer"));
 const auto pi        = toml::get<double          >(data.at("pi"));
 const auto numbers   = toml::get<std::vector<int>>(data.at("numbers"));
@@ -101,18 +148,26 @@ const auto tab       = toml::get<toml::Table>(data.at("tab"));
 const auto key       = toml::get<std::string>( tab.at("key"));
 ```
 
-When you pass an exact TOML type that does not require type conversion, `toml::get` returns also a reference through which you can modify the content.
+When you pass an exact TOML type that does not require type conversion,
+`toml::get` returns a reference through which you can modify the content.
 
 ```cpp
-toml::get<toml::integer>(data["answer"]) = 6 * 9;
+auto  data   = toml::parse("sample.toml");
+auto& answer = toml::get<toml::integer>(data["answer"]);     // get reference
+answer = 6 * 9;                                              // write to data.answer
 std::cout << toml::get<int>(data.at("answer")) << std::endl; // 54
 ```
 
-If the specified type requires conversion, you can't take a reference to the value. See also [underlying types](#underlying-types).
+If the specified type requires conversion, you can't take a reference to the value.
+See also [underlying types](#underlying-types).
 
-#### Passing invalid type to toml::get
+NOTE: To enable to get a reference, conversions between Float and Integer are not supported.
 
-If you choose the invalid type, `toml::type_error` will be thrown. Similar to the `syntax_error`, toml11 also displays informative error messages. The error message when you choose `int` to get `string` value would be like this.
+### In the case of type error
+
+If you pass an invalid type to `toml::get`, `toml::type_error` will be thrown.
+Similar to the case of syntax error, toml11 also displays clean error messages.
+The error message when you choose `int` to get `string` value would be like this.
 
 ```console
 terminate called after throwing an instance of 'toml::type_error'
@@ -122,13 +177,21 @@ terminate called after throwing an instance of 'toml::type_error'
    |         ~~~~~~~~~~~~~~ the actual type is string
 ```
 
-NOTE: In order to show this kind of error message, all the toml values have 1 shared_ptr that points the corresponding byte sequence and 2 iterators that point the range. It is recommended to destruct all the `toml::value` classes after configuring your application to save memory resources.
+NOTE: In order to show this kind of error message, all the toml values have
+pointers to represent its range in a file. The entire contents of a file is
+shared by `toml::value`s and remains on the heap memory. It is recommended to
+destruct all the `toml::value` classes after configuring your application
+if you have a large TOML file compared to the memory resource.
 
-### Getting arrays
+## Getting an array
 
-You can set any kind of `container` class to obtain a `toml::array` except for `map`-like classes.
+You can get any kind of `container` class from a `toml::array`
+except for `map`-like classes.
 
 ``` cpp
+// # sample.toml
+// numbers = [1,2,3]
+
 const auto vc  = toml::get<std::vector<int>  >(data.at("numbers"));
 const auto ls  = toml::get<std::list<int>    >(data.at("numbers"));
 const auto dq  = toml::get<std::deque<int>   >(data.at("numbers"));
@@ -137,16 +200,16 @@ const auto ar  = toml::get<std::array<int, 3>>(data.at("numbers"));
 // it will throw toml::type_error because std::array is not resizable.
 ```
 
-Surprisingly, you can also get a `toml::array` as `std::pair` and `std::tuple.`
+Surprisingly, you can also get `std::pair`s and `std::tuple`s from `toml::array`.
 
 ```cpp
 const auto tp = toml::get<std::tuple<short, int, unsigned int>>(data.at("numbers"));
 ```
 
-The case when you need this functionality is to get an array of arrays.
+This functionality is helpful when you have the following toml file.
 
 ```toml
-aofa = [[1,2,3], ["foo", "bar", "baz"]] # toml allows this
+array_of_arrays = [[1, 2, 3], ["foo", "bar", "baz"]] # toml allows this
 ```
 
 What is the corresponding C++ type? Obviously, it is a `std::pair` of `std::vector`s.
@@ -154,23 +217,28 @@ What is the corresponding C++ type? Obviously, it is a `std::pair` of `std::vect
 ```cpp
 const auto aofa = toml::get<
     std::pair<std::vector<int>, std::vector<std::string>>
-    >(data.at("aofa"));
+    >(data.at("array_of_arrays"));
 ```
 
-If you don't know what the type is inside the array, you can use `toml::array`, which is a `std::vector` of `toml::value`, instead.
+If you don't know the type of the elements, you can use `toml::array`,
+which is a `std::vector` of `toml::value`, instead.
 
 ```cpp
-const auto aofa  = toml::get<toml::array>(data.at("aofa"));
-const auto first = toml::get<toml::array>(aofa.at(0));
+const auto aofa  = toml::get<toml::array>(data.at("array_of_arrays"));
+const auto first = toml::get<std::vector<int>>(aofa.at(0));
 ```
 
-See also [expecting conversion](#expecting-conversion) and [checking-value-type](#checking-value-type).
+See also [expecting conversion](#expecting-conversion)
+and [checking-value-type](#checking-value-type).
 
-### Getting tables
+## Getting a table
 
-`toml::table` is a key component of this library, which is an alias of a `std::unordered_map` from `toml::key (a.k.a. std::string)` to `toml::value`. `toml::parse` returns this as a result.
+`toml::table` is a key component of this library, which is an alias of
+a `std::unordered_map` from `toml::key (a.k.a. std::string)` to `toml::value`.
+`toml::parse` returns this.
 
-Since it is just an alias of `std::unordered_map`, it has all the functionalities that `std::unordered_map` has, e.g. `operator[]`, `count`, and `find`.
+Since it is just an alias of `std::unordered_map`, it has all the functionalities
+that `std::unordered_map` has, e.g. `operator[]`, `count`, and `find`.
 
 ```cpp
 toml::table data = toml::parse("example.toml");
@@ -180,7 +248,8 @@ if(data.count("title") != 0)
 }
 ```
 
-When all the values of the table have the same type, toml11 allows you to convert a `toml::table` to a `map` that contains the convertible type.
+When all the values of the table have the same type, toml11 allows you to
+convert a `toml::table` to a `map` that contains the convertible type.
 
 ```toml
 [tab]
@@ -189,14 +258,16 @@ key2 = "bar" # toml String
 ```
 
 ```cpp
+const auto data = toml::parse("sample.toml");
 const auto tab = toml::get<std::map<std::string, std::string>>(data.at("tab"));
 std::cout << tab["key1"] << std::endl; // foo
 std::cout << tab["key2"] << std::endl; // bar
 ```
 
-### Dotted keys
+## Dotted keys
 
-TOML v0.5.0 has a new feature named "dotted keys". You can chain keys to represent the structure of the data.
+TOML v0.5.0 has a new feature named "dotted keys".
+You can chain keys to represent the structure of the data.
 
 ```toml
 physical.color = "orange"
@@ -218,38 +289,50 @@ const auto physical = toml::get<toml::table>(data.at("physical"));
 const auto color    = toml::get<std::string>(physical.at("color"));
 ```
 
-### An array of tables
+## Getting an array of tables
 
-An array of tables is just an array of tables. You can get it completely in the same way as the other arrays and tables.
+An array of tables is just an array of tables.
+You can get it completely in the same way as the other arrays and tables.
 
 ```toml
-array_of_inline_table = [{key = "value1"}, {key = "value2"}, {key = "value3"}]
+# sample.toml
+array_of_inline_tables = [{key = "value1"}, {key = "value2"}, {key = "value3"}]
 
-[[array_of_table]]
+[[array_of_tables]]
 key = "value4"
-[[array_of_table]]
+[[array_of_tables]]
 key = "value5"
-[[array_of_table]]
+[[array_of_tables]]
 key = "value6"
 ```
 
 ```cpp
-const auto aot1 = toml::get<std::vector<toml::table>>(data.at("array_of_inline_table"));
-const auto aot2 = toml::get<std::vector<toml::table>>(data.at("array_of_table"));
+const auto data = toml::parse("sample.toml");
+const auto aot1 = toml::get<std::vector<toml::table>>(data.at("array_of_inline_tables"));
+const auto aot2 = toml::get<std::vector<toml::table>>(data.at("array_of_tables"));
 ```
 
-### Cost of conversion
+## Cost of conversion
 
-Although `toml::get` is convenient, it has additional copy-cost because it copies data contained in `toml::value` to the user-specified type. Of course in some case this overhead is not ignorable.
+Although `toml::get` is convenient, it has additional copy-cost because
+it copies data contained in `toml::value` to the user-specified type.
+Of course in some cases this overhead is not ignorable.
 
-By passing the exact types, `toml::get` returns reference that has nealy zero overhead.
+```cpp
+// the following code constructs a std::vector.
+// it requires heap allocation for vector and element conversion.
+const auto array = toml::get<std::vector<int>>(data.at("foo"));
+```
+
+By passing the exact types, `toml::get` returns reference that has no overhead.
 
 ``` cpp
 const auto& tab     = toml::get<toml::array>(data.at("tab"));
 const auto& numbers = toml::get<toml::table>(data.at("numbers"));
 ```
 
-Unfortunately, in this case you need to call `toml::get` each time you access to the element of `toml::array` because `toml::array` is an array of `toml::value`.
+In this case you need to call `toml::get` each time you access to
+the element of `toml::array` because `toml::array` is an array of `toml::value`.
 
 ```cpp
 const auto& num0 = toml::get<toml::integer>(numbers.at(0));
@@ -257,34 +340,64 @@ const auto& num1 = toml::get<toml::integer>(numbers.at(1));
 const auto& num2 = toml::get<toml::integer>(numbers.at(2));
 ```
 
-### Datetime and its variants
+## Getting datetime and its variants
 
-TOML v0.5.0 has 4 different datetime objects, `local_date`, `local_time`, `local_datetime`, and `offset_datetime`. With toml11, you can convert `local_time` to your favorite `std::chrono::duration` and others to `std::chrono::system_clock::time_point`.
+TOML v0.5.0 has 4 different datetime objects, `local_date`, `local_time`,
+`local_datetime`, and `offset_datetime`.
+
+Since `local_date`, `local_datetime`, and `offset_datetime` represent a time
+point, you can convert them to `std::chrono::system_clock::time_point`.
+
+Contrary, `local_time` does not represents a time point because they lack a
+date information, but it can be converted to `std::chrono::duration` that
+represents a duration from the beginning of the day, `00:00:00.000`.
 
 ```toml
-time = 12:30:00
 date = 2018-12-23
+time = 12:30:00
+l_dt = 2018-12-23T12:30:00
+o_dt = 2018-12-23T12:30:00+09:30
 ```
 
 ```cpp
-const auto dur = toml::get<std::chrono::minutes>(data.at("time")); // 12 * 60 + 30 min
-const auto tp  = toml::get<std::chrono::system_clock::time_point>(data.at("date"));
+const auto data = toml::parse("sample.toml");
+
+const auto date = toml::get<std::chrono::system_clock::time_point>(data.at("date"));
+const auto l_dt = toml::get<std::chrono::system_clock::time_point>(data.at("l_dt"));
+const auto o_dt = toml::get<std::chrono::system_clock::time_point>(data.at("o_dt"));
+
+const auto time = toml::get<std::chrono::minutes>(data.at("time")); // 12 * 60 + 30 min
 ```
 
-### Getting with a fallback
+toml11 contains datetime as its own struct.
+You can see the definitions in [toml/datetime.hpp](toml/datetime.hpp).
 
- `toml::get_or` returns a default value if `toml::get<T>` failed.
+## Getting with a fallback
+
+`toml::get_or` returns a default value if `toml::get<T>` failed.
 
 ```cpp
-toml::table data; // empty table!
-const auto value = toml::get_or(data, "key", 42); // value => int 42.
+toml::value v("foo"); // v contains String
+const int value = toml::get_or(v, 42); // conversion fails. it returns 42.
 ```
 
-`toml::get_or` automatically deduces what type you want to get from the default value you passed.
+`toml::get_or` automatically deduces what type you want to get from
+the default value you passed.
 
-### Expecting conversion
+To get a reference through this function, take care about the default value.
 
-By using `toml::expect`, you will get your expected value or an error message without throwing `toml::type_error`.
+```cpp
+toml::value v("foo"); // v contains String
+toml::integer& i = toml::get_or(v, 42); // does not work because binding `42`
+                                        // to `integer&` is invalid
+toml::integer opt = 42;
+toml::integer& i = toml::get_or(v, opt); // this works.
+```
+
+## Expecting conversion
+
+By using `toml::expect`, you will get your expected value or an error message
+without throwing `toml::type_error`.
 
 ```cpp
 const auto value = toml::expect<std::string>(data.at("title"));
@@ -305,23 +418,26 @@ const auto value = toml::expect<int>(data.at("number"))
     }).unwrap_or(/*default value =*/ 3.14);
 ```
 
-### Finding value from table
+## Finding a value from a table
 
-toml11 provides utility function to find a value from `toml::table`. Of course, you can do this in your own way with `toml::get` because it just searches an  `unordered_map` and returns a value if it exists.
+toml11 provides utility function to find a value from `toml::table`.
+Of course, you can do this in your own way with `toml::get` because
+it just searches an  `unordered_map` and returns a value if it exists.
 
 ```cpp
 const auto data = toml::parse("example.toml");
 const auto num  = toml::find<int>(data, "num", /*for err msg*/"example.toml");
 ```
 
-If the value does not exist, it throws `std::out_of_range` with informative error message.
+If the value does not exist, it throws `std::out_of_range` with an error message.
 
 ```console
 terminate called after throwing an instance of 'std::out_of_range'
   what():  [error] key "num" not found in example.toml
 ```
 
-You can use this with a `toml::value` that is expected to be a `toml::table`. It automatically casts the value to table.
+You can use this with a `toml::value` that is expected to be a `toml::table`.
+It automatically casts the value to table.
 
 ```cpp
 const auto data = toml::parse("example.toml");
@@ -331,7 +447,9 @@ const auto num  = toml::find<int>(data.at("table"), "num");
 // num = 42
 ```
 
-In this case, because the value `data.at("table")` knows the locatoin of itself, you don't need to pass where you find the value. `toml::find` will show you a great error message.
+In this case, because the value `data.at("table")` knows the locatoin of itself,
+you don't need to pass where you find the value.
+`toml::find` will show you an error message including table location.
 
 ```console
 terminate called after throwing an instance of 'std::out_of_range'
@@ -343,66 +461,279 @@ terminate called after throwing an instance of 'std::out_of_range'
 
 If it's not a `toml::table`, the same error as "invalid type" would be thrown.
 
-### Checking value type
+There is another utility function, `toml::find_or`.
+It is almost same as `toml::find`, but returns a default value if the value is
+not found or has a different type, like `toml::get_or`.
 
-When you don't know the exact type of toml-value, you can get `enum` type from `toml::value`.
+```cpp
+const auto data = toml::parse("example.toml");
+const auto num  = toml::find_or(data.at("table"), "num", 42);
+```
+
+## Checking value type
+
+You can check what type of value does `toml::value` contains by `is_*` function.
+
+```cpp
+toml::value v = /* ... */;
+if(v.is_integer() && toml::get<int>(v) == 42)
+{
+    std::cout << "value is 42" << std::endl;
+}
+```
+
+The complete list of the functions is below.
+
+```cpp
+const toml::value v(/*...*/);
+v.is_boolean();
+v.is_integer();
+v.is_float();
+v.is_string();
+v.is_offset_datetime();
+v.is_local_datetime();
+v.is_local_date();
+v.is_local_time();
+v.is_array();
+v.is_table();
+v.is_uninitialized();
+```
+
+Also, you can get `enum class` value from `toml::value`.
 
 ```cpp
 switch(data.at("something").type())
 {
-    case toml::value_t::Integer: /* do some stuff */; break;
-    case toml::value_t::Float  : /* do some stuff */; break;
-    case toml::value_t::String : /* do some stuff */; break;
+    case toml::value_t::Integer: /*do some stuff*/ ; break;
+    case toml::value_t::Float  : /*do some stuff*/ ; break;
+    case toml::value_t::String : /*do some stuff*/ ; break;
     default : throw std::runtime_error(
         "unexpected type : " + toml::stringize(data.at("something").type()));
 }
 ```
 
-### Fill only the matched value
+The complete list of the `enum`s can be found in the section
+[underlying types](#underlying-types).
 
-The more sophisticated way is using `toml::from_toml` and `std::tie`.
+The `enum`s can be used as a parameter of `toml::value::is` function like the following.
 
 ```cpp
-toml::table data{{"something", toml::value("foo")}};
-int         i = 0;
-double      d = 0.;
-std::string s;
-toml::from_toml(std::tie(i, d, s), data.at("something"));
-std::cout << i << ", " << d << ", " << s << std::endl; // 0, 0, foo
+toml::value v = /* ... */;
+if(v.is(toml::value_t::Boolean)) // ...
 ```
 
-Here, only matched value will be filled. The others are left intact after calling `from_toml`.
-It should be noted that `toml::from_toml` returns as usual even if there are no matched type.
+## Visiting a toml::value
 
-`from_toml` can be used also for single type. 
+toml11 provides `toml::visit` to apply a function to `toml::value` in the
+same way as `std::variant`.
 
 ```cpp
-int i = 0;
-toml::from_toml(i, data.at("something"));
+const toml::value v(3.14);
+toml::visit([](const auto& val) -> void {
+        std::cout << val << std::endl;
+    }, v);
 ```
 
-### Sanitizing UTF-8 codepoints
+The function object that would be passed to `toml::visit` must be able to
+recieve all the possible TOML types. Also, the result types should be the same
+each other.
 
-toml11 shows warning if a value of an escape sequence used to represent unicode character exceeds the unicode range.
+## TOML literal
+
+toml11 supports `"..."_toml` literal.
+It accept both a bare value and a file content.
+
+```cpp
+using namespace toml::literals::toml_literals;
+
+// `_toml` can convert a bare value without key
+const toml::value v = u8"0xDEADBEEF"_toml;
+// v is an Integer value containing 0xDEADBEEF.
+
+// raw string literal (`R"(...)"` is useful for this purpose)
+const toml::value t = u8R"(
+    title = "this is TOML literal"
+    [table]
+    key = "value"
+)"_toml;
+// the literal will be parsed and the result will be contained in t
+```
+
+The literal function is defined in the same way as the standard library literals
+such as `std::literals::string_literals::operator""s`.
+
+```cpp
+namespace toml
+{
+inline namespace literals
+{
+inline namespace toml_literals
+{
+toml::value operator""_toml(const char* str, std::size_t len);
+
+} // toml_literals
+} // literals
+} // toml
+```
+
+Access to the operator can be gained with `using namespace toml::literals;`,
+`using namespace toml::toml_literals`, and `using namespace toml::literals::toml_literals`.
+
+## Conversion between toml value and arbitrary types
+
+You can also use `toml::get` and other related functions with the types you defined
+after you implement some stuff.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+
+const auto data = toml::parse("example.toml");
+
+const foo f = toml::get<ext::foo>(data.at("foo"));
+```
+
+There are 2 ways to use `toml::get` with the types that you defined.
+
+The first one is to implement `from_toml(const toml::value&)` member function.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+
+    void from_toml(const toml::value& v)
+    {
+        this->a = toml::find<int        >(v, "a");
+        this->b = toml::find<double     >(v, "b");
+        this->c = toml::find<std::string>(v, "c");
+        return;
+    }
+};
+} // ext
+```
+
+In this way, because `toml::get` first constructs `foo` without arguments,
+the type should be default-constructible.
+
+The second is to implement specialization of `toml::from` for your type.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+
+namespace toml
+{
+template<>
+struct from<ext::foo>
+{
+    ext::foo from_toml(const toml::value& v)
+    {
+        ext::foo f;
+        f.a = toml::find<int        >(v, "a");
+        f.b = toml::find<double     >(v, "b");
+        f.c = toml::find<std::string>(v, "c");
+        return f;
+    }
+};
+} // toml
+```
+
+In this way, since the conversion function is defined outside of the class,
+you can add conversion between `toml::value` and classes defined in another library.
+
+Note that you cannot implement both of the functions because the overload
+resolution of `toml::get` will be ambiguous.
+
+----
+
+The opposite direction is also supported in a similar way. You can directly
+pass your type to `toml::value`'s constructor by introducing `into_toml` or
+`toml::into<T>`.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+
+    toml::table into_toml() const // you need to mark it const.
+    {
+        return toml::table{{"a", this->a}, {"b", this->b}, {"c", this->c}};
+    }
+};
+} // ext
+
+ext::foo    f{42, 3.14, "foobar"};
+toml::value v(f);
+```
+
+The definition of `toml::into<T>` is similar to `toml::from<T>`.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+
+namespace toml
+{
+template<>
+struct into<ext::foo>
+{
+    toml::table into_toml(const ext::foo& f)
+    {
+        return toml::table{{"a", f.a}, {"b", f.b}, {"c", f.c}};
+    }
+};
+} // toml
+
+ext::foo    f{42, 3.14, "foobar"};
+toml::value v(f);
+```
+
+Any type that can be converted to `toml::value`, e.g. `toml::table`, `toml::array`,
+is okay to return from `into_toml`.
+
+## Invalid UTF-8 codepoints
+
+toml11 throws `syntax_error` if a value of an escape sequence
+representing unicode character is not a valid UTF-8 codepoint.
 
 ```console
-[warning] input codepoint (0011FFFF) is too large to decode as a unicode character. The result may not be able to render to your screen.
- --> example.toml
- 3 | exceeds_unicode = "\U0011FFFF example"
-   |                     ~~~~~~~~~ should be in [0x00..0x10FFFF]
+  what():  [error] toml::read_utf8_codepoint: input codepoint is too large.
+ --> utf8.toml
+ 1 | exceeds_unicode = "\U0011FFFF example"
+   |                              ^--------- should be in [0x00..0x10FFFF]
 ```
 
-Also, toml11 throws `std::domain_error` if the code point exceeds the range that can be represented by utf-8.
-
-```console
-terminate called after throwing an instance of 'std::range_error'
-  what():  [error] input codepoint (0020FFFF) is too large to encode as utf-8.
- --> example.toml
- 3 | exceeds_utf8    = "\U0020FFFF example"
-   |                     ~~~~~~~~~ should be in [0x00..0x10FFFF]
-```
-
-### Formatting your error
+## Formatting user-defined error messages
 
 When you encounter an error after you read the toml value, you may want to
 show the error with the value.
@@ -455,6 +786,102 @@ you will get an error message like this.
    |       ~~ maximum number here
 ```
 
+## Serializing TOML data
+
+toml11 (after v2.1.0) enables you to serialize data into toml format.
+
+```cpp
+const auto data = toml::table{{"foo", 42}, {"bar", "baz"}};
+std::cout << data << std::endl;
+// bar = "baz"
+// foo = 42
+```
+
+toml11 automatically makes a small table and small array inline.
+You can specify the width to make them inline by `std::setw` for streams.
+
+```cpp
+const auto data = toml::table{
+    {"qux",    toml::table{{"foo", 42}, {"bar", "baz"}}},
+    {"quux",   toml::array{"small", "array", "of", "strings"}},
+    {"foobar", toml::array{"this", "array", "of", "strings", "is", "too", "long",
+                           "to", "print", "into", "single", "line", "isn't", "it?"}},
+};
+
+// the threshold becomes 80.
+std::cout << std::setw(80) << data << std::endl;
+// foobar = [
+// "this","array","of","strings","is","too","long","to","print","into",
+// "single","line","isn't","it?",
+// ]
+// quux = ["small","array","of","strings"]
+// qux = {bar="baz",foo=42}
+
+
+// the width is 0. nothing become inline.
+std::cout << std::setw(0) << data << std::endl;
+// foobar = [
+// "this",
+// ... (snip)
+// "it?",
+// ]
+// quux = [
+// "small",
+// "array",
+// "of",
+// "strings",
+// ]
+// [qux]
+// bar = "baz"
+// foo = 42
+```
+
+It is recommended to set width before printing data. Some I/O functions changes
+width to 0, and it makes all the stuff (including `toml::array`) multiline.
+The resulting files becomes too long.
+
+To control the precision of floating point numbers, you need to pass
+`std::setprecision` to stream.
+
+```cpp
+const auto data = toml::table{
+    {"pi", 3.141592653589793},
+    {"e",  2.718281828459045}
+};
+std::cout << std::setprecision(17) << data << std::endl;
+// e = 2.7182818284590451
+// pi = 3.1415926535897931
+std::cout << std::setprecision( 7) << data << std::endl;
+// e = 2.718282
+// pi = 3.141593
+```
+
+There is another way to format toml values, `toml::format()`.
+It returns `std::string` that represents a value.
+
+```cpp
+const toml::value v{{"a", 42}};
+const std::string fmt = toml::format(v);
+// a = 42
+```
+
+Note that since `toml::format` formats a value, the resulting string may lack
+the key value.
+
+```cpp
+const toml::value v{3.14};
+const std::string fmt = toml::format(v);
+// 3.14
+```
+
+To control the width and precision, `toml::format` receives optional second and
+third arguments to set them. By default, the witdh is 80 and the precision is
+`std::numeric_limits<double>::max_digit10`.
+
+```cpp
+const auto serial = toml::format(data, /*width = */ 0, /*prec = */ 17);
+```
+
 ## Underlying types
 
 The toml types (can be used as `toml::*` in this library) and corresponding `enum` names are listed in the table below.
@@ -468,23 +895,48 @@ The toml types (can be used as `toml::*` in this library) and corresponding `enu
 | LocalDate      | `toml::local_date`                           | `toml::value_t::LocalDate`      |
 | LocalTime      | `toml::local_time`                           | `toml::value_t::LocalTime`      |
 | LocalDatetime  | `toml::local_datetime`                       | `toml::value_t::LocalDatetime`  |
-| OffsetDatetime | `toml::offset_datetime`                      | `toml::value_t::offsetDatetime` |
+| OffsetDatetime | `toml::offset_datetime`                      | `toml::value_t::OffsetDatetime` |
 | Array          | `std::vector<toml::value>`                   | `toml::value_t::Array`          |
-| Table          | `std::unordered_map<std::string, toml::key>` | `toml::value_t::Table`          |
+| Table          | `std::unordered_map<toml::key, toml::value>` | `toml::value_t::Table`          |
 
-`toml::string` is effectively the same as `std::string` but has an additional flag that represents a kind of a string, `string_t::basic` and `string_t::literal`. Although `std::string` is not an exact toml type, still you can get a reference that points to internal `std::string` by using `toml::get<std::string>()` for convenience.
+`toml::string` is effectively the same as `std::string` but has an additional
+flag that represents a kind of a string, `string_t::basic` and `string_t::literal`.
+Although `std::string` is not an exact toml type, still you can get a reference
+that points to internal `std::string` by using `toml::get<std::string>()` for convenience.
 
-`Datetime` variants are `struct` that are defined in this library. Because `std::chrono::system_clock::time_point` is a __time point__, not capable of representing a Local Time independent from a specific day.
+`Datetime` variants are `struct` that are defined in this library.
+Because `std::chrono::system_clock::time_point` is a __time point__,
+not capable of representing a Local Time independent from a specific day.
 
 It is recommended to get `Datetime`s as `std::chrono` classes through `toml::get`.
 
+## Running Tests
+
+To run test codes, you need to clone toml-lang/toml repository under `build/` directory
+because some of the test codes read a file in the repository.
+
+```sh
+$ mkdir build
+$ cd build
+$ git clone https://github.com/toml-lang/toml.git
+$ cmake ..
+$ make
+$ make test
+```
+
+To run the language agnostic test suite, you need to compile
+`tests/check_toml_test.cpp` and pass it to the tester.
+
 ## Contributors
 
-I thank the contributor for providing great feature to this repository.
+I appreciate the help of the contributors who introduced the great feature to this library.
 
 - Guillaume Fraux (@Luthaf)
   - Windows support and CI on Appvayor
   - Intel Compiler support
+- Quentin Khan (@xaxousis)
+  - Found & Fixed a bug around ODR
+  - Improved error messages for invaild keys to show the location where the parser fails
 
 ## Licensing terms
 

tests/CMakeLists.txt

@@ -20,13 +20,16 @@ set(TEST_NAMES
     test_parse_inline_table
     test_parse_key
     test_parse_table_key
+    test_literals
     test_get
     test_get_related_func
-    test_to_toml
     test_from_toml
     test_parse_file
+    test_serialize_file
     test_parse_unicode
     test_error_detection
+    test_format_error
+    test_extended_conversions
 )
 
 CHECK_CXX_COMPILER_FLAG("-Wall" COMPILER_SUPPORTS_WALL)
@@ -96,3 +99,8 @@ foreach(TEST_NAME ${TEST_NAMES})
         )
     endif()
 endforeach(TEST_NAME)
+
+# this test is to check it compiles. it will not run
+add_executable(test_multiple_translation_unit
+               test_multiple_translation_unit_1.cpp
+               test_multiple_translation_unit_2.cpp)

tests/check.cpp

@@ -0,0 +1,41 @@
+#include "toml.hpp"
+#include <iostream>
+#include <iomanip>
+
+int main(int argc, char **argv)
+{
+    if(argc != 3)
+    {
+        std::cerr << "usage: ./check [filename] [valid|invalid]" << std::endl;
+        return 1;
+    }
+
+    const std::string file_kind(argv[2]);
+
+    try
+    {
+        const auto data = toml::parse(argv[1]);
+        std::cout << std::setprecision(16) << std::setw(80) << data;
+        if(file_kind == "valid")
+        {
+            return 0;
+        }
+        else
+        {
+            return 1;
+        }
+    }
+    catch(const toml::syntax_error& err)
+    {
+        std::cout << "what(): " << err.what() << std::endl;
+        if(file_kind == "invalid")
+        {
+            return 0;
+        }
+        else
+        {
+            return 1;
+        }
+    }
+    return 127;
+}

tests/check_toml_test.cpp

@@ -0,0 +1,142 @@
+#include "toml.hpp"
+#include <iostream>
+#include <iomanip>
+
+struct json_serializer
+{
+    void operator()(toml::boolean v)
+    {
+        std::cout << "{\"type\":\"bool\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(toml::integer v)
+    {
+        std::cout << "{\"type\":\"integer\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(toml::floating v)
+    {
+        std::cout << "{\"type\":\"float\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(const toml::string& v)
+    {
+        // since toml11 automatically convert string to multiline string that is
+        // valid only in TOML, we need to format the string to make it valid in
+        // JSON.
+        std::cout << "{\"type\":\"string\",\"value\":\""
+                  << this->escape_string(v.str) << "\"}";
+        return ;
+    }
+    void operator()(const toml::local_time& v)
+    {
+        std::cout << "{\"type\":\"local_time\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(const toml::local_date& v)
+    {
+        std::cout << "{\"type\":\"local_date\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(const toml::local_datetime& v)
+    {
+        std::cout << "{\"type\":\"local_datetime\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(const toml::offset_datetime& v)
+    {
+        std::cout << "{\"type\":\"datetime\",\"value\":\"" << toml::value(v) << "\"}";
+        return ;
+    }
+    void operator()(const toml::array& v)
+    {
+        if(!v.empty() && v.front().is_table())
+        {
+            std::cout << '[';
+            bool is_first = true;
+            for(const auto& elem : v)
+            {
+                if(!is_first) {std::cout << ", ";}
+                is_first = false;
+                toml::visit(*this, elem);
+            }
+            std::cout << ']';
+        }
+        else
+        {
+            std::cout << "{\"type\":\"array\",\"value\":[";
+            bool is_first = true;
+            for(const auto& elem : v)
+            {
+                if(!is_first) {std::cout << ", ";}
+                is_first = false;
+                toml::visit(*this, elem);
+            }
+            std::cout << "]}";
+        }
+        return ;
+    }
+    void operator()(const toml::table& v)
+    {
+        std::cout << '{';
+        bool is_first = true;
+        for(const auto& elem : v)
+        {
+            if(!is_first) {std::cout << ", ";}
+            is_first = false;
+            std::cout << toml::format(toml::string(elem.first),
+                                      std::numeric_limits<std::size_t>::max());
+            std::cout << ':';
+            toml::visit(*this, elem.second);
+        }
+        std::cout << '}';
+        return ;
+    }
+
+    std::string escape_string(const std::string& s) const
+    {
+        std::string retval;
+        for(const char c : s)
+        {
+            switch(c)
+            {
+                case '\\': {retval += "\\\\"; break;}
+                case '\"': {retval += "\\\""; break;}
+                case '\b': {retval += "\\b";  break;}
+                case '\t': {retval += "\\t";  break;}
+                case '\f': {retval += "\\f";  break;}
+                case '\n': {retval += "\\n";  break;}
+                case '\r': {retval += "\\r";  break;}
+                default  : {retval += c;      break;}
+            }
+        }
+        return retval;
+    }
+};
+
+int main()
+{
+    try
+    {
+        std::vector<char> buf;
+        std::cin.peek();
+        while(!std::cin.eof())
+        {
+            buf.push_back(std::cin.get());
+            std::cin.peek();
+        }
+        std::string bufstr(buf.begin(), buf.end());
+
+        std::istringstream ss(bufstr);
+
+        const auto data = toml::parse(ss);
+        std::cout << std::setprecision(std::numeric_limits<double>::max_digits10);
+        toml::visit(json_serializer(), data);
+        return 0;
+    }
+    catch(const toml::syntax_error& err)
+    {
+        std::cout << "what(): " << err.what() << std::endl;
+        return 1;
+    }
+}

tests/test_extended_conversions.cpp

@@ -0,0 +1,116 @@
+#define BOOST_TEST_MODULE "test_extended_conversions"
+#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
+#include <boost/test/unit_test.hpp>
+#else
+#define BOOST_TEST_NO_LIB
+#include <boost/test/included/unit_test.hpp>
+#endif
+#include <toml.hpp>
+
+namespace extlib
+{
+struct foo
+{
+    int a;
+    std::string b;
+};
+struct bar
+{
+    int a;
+    std::string b;
+
+    void from_toml(const toml::value& v)
+    {
+        this->a = toml::find<int>(v, "a");
+        this->b = toml::find<std::string>(v, "b");
+        return ;
+    }
+
+    toml::table into_toml() const
+    {
+        return toml::table{{"a", this->a}, {"b", this->b}};
+    }
+};
+} // extlib
+
+namespace toml
+{
+template<>
+struct from<extlib::foo>
+{
+    static extlib::foo from_toml(const toml::value& v)
+    {
+        return extlib::foo{toml::find<int>(v, "a"), toml::find<std::string>(v, "b")};
+    }
+};
+
+template<>
+struct into<extlib::foo>
+{
+    static toml::table into_toml(const extlib::foo& f)
+    {
+        return toml::table{{"a", f.a}, {"b", f.b}};
+    }
+};
+} // toml
+
+
+BOOST_AUTO_TEST_CASE(test_conversion_by_member_methods)
+{
+    const toml::value v{{"a", 42}, {"b", "baz"}};
+
+    const auto foo = toml::get<extlib::foo>(v);
+    BOOST_CHECK_EQUAL(foo.a, 42);
+    BOOST_CHECK_EQUAL(foo.b, "baz");
+
+    const toml::value v2(foo);
+
+    BOOST_CHECK_EQUAL(v, v2);
+}
+
+BOOST_AUTO_TEST_CASE(test_conversion_by_specialization)
+{
+    const toml::value v{{"a", 42}, {"b", "baz"}};
+
+    const auto bar = toml::get<extlib::bar>(v);
+    BOOST_CHECK_EQUAL(bar.a, 42);
+    BOOST_CHECK_EQUAL(bar.b, "baz");
+
+    const toml::value v2(bar);
+
+    BOOST_CHECK_EQUAL(v, v2);
+}
+
+BOOST_AUTO_TEST_CASE(test_recursive_conversion)
+{
+    const toml::value v{
+        toml::table{{"a", 42}, {"b", "baz"}},
+        toml::table{{"a", 43}, {"b", "qux"}},
+        toml::table{{"a", 44}, {"b", "quux"}},
+        toml::table{{"a", 45}, {"b", "foobar"}},
+    };
+
+    const auto foos = toml::get<std::vector<extlib::foo>>(v);
+    BOOST_CHECK_EQUAL(foos.size()  , 4ul);
+    BOOST_CHECK_EQUAL(foos.at(0).a , 42);
+    BOOST_CHECK_EQUAL(foos.at(1).a , 43);
+    BOOST_CHECK_EQUAL(foos.at(2).a , 44);
+    BOOST_CHECK_EQUAL(foos.at(3).a , 45);
+
+    BOOST_CHECK_EQUAL(foos.at(0).b , "baz");
+    BOOST_CHECK_EQUAL(foos.at(1).b , "qux");
+    BOOST_CHECK_EQUAL(foos.at(2).b , "quux");
+    BOOST_CHECK_EQUAL(foos.at(3).b , "foobar");
+
+    const auto bars = toml::get<std::vector<extlib::bar>>(v);
+    BOOST_CHECK_EQUAL(bars.size()  , 4ul);
+    BOOST_CHECK_EQUAL(bars.at(0).a , 42);
+    BOOST_CHECK_EQUAL(bars.at(1).a , 43);
+    BOOST_CHECK_EQUAL(bars.at(2).a , 44);
+    BOOST_CHECK_EQUAL(bars.at(3).a , 45);
+
+    BOOST_CHECK_EQUAL(bars.at(0).b , "baz");
+    BOOST_CHECK_EQUAL(bars.at(1).b , "qux");
+    BOOST_CHECK_EQUAL(bars.at(2).b , "quux");
+    BOOST_CHECK_EQUAL(bars.at(3).b , "foobar");
+}

tests/test_format_error.cpp

@@ -0,0 +1,75 @@
+#define BOOST_TEST_MODULE "test_value"
+#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
+#include <boost/test/unit_test.hpp>
+#else
+#define BOOST_TEST_NO_LIB
+#include <boost/test/included/unit_test.hpp>
+#endif
+#include <toml.hpp>
+
+// to check it successfully compiles. it does not check the formatted string.
+
+BOOST_AUTO_TEST_CASE(test_1_value)
+{
+    toml::value val(42);
+
+    {
+        const std::string pretty_error =
+            toml::format_error("[error] test error", val, "this is a value");
+        std::cout << pretty_error << std::endl;
+    }
+
+    {
+        const std::string pretty_error =
+            toml::format_error("[error] test error", val, "this is a value",
+                               {"this is a hint"});
+        std::cout << pretty_error << std::endl;
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_2_values)
+{
+    toml::value v1(42);
+    toml::value v2(3.14);
+    {
+        const std::string pretty_error =
+            toml::format_error("[error] test error with two values",
+                               v1, "this is the answer",
+                               v2, "this is the pi");
+        std::cout << pretty_error << std::endl;
+    }
+
+    {
+        const std::string pretty_error =
+            toml::format_error("[error] test error with two values",
+                               v1, "this is the answer",
+                               v2, "this is the pi",
+                               {"hint"});
+        std::cout << pretty_error << std::endl;
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_3_values)
+{
+    toml::value v1(42);
+    toml::value v2(3.14);
+    toml::value v3("foo");
+    {
+        const std::string pretty_error =
+            toml::format_error("[error] test error with two values",
+                               v1, "this is the answer",
+                               v2, "this is the pi",
+                               v3, "this is a meta-syntactic variable");
+        std::cout << pretty_error << std::endl;
+    }
+
+    {
+        const std::string pretty_error =
+            toml::format_error("[error] test error with two values",
+                               v1, "this is the answer",
+                               v2, "this is the pi",
+                               v3, "this is a meta-syntactic variable",
+                               {"hint 1", "hint 2"});
+        std::cout << pretty_error << std::endl;
+    }
+}

tests/test_get_related_func.cpp

@@ -45,21 +45,194 @@ BOOST_AUTO_TEST_CASE(test_find)
 
 BOOST_AUTO_TEST_CASE(test_get_or)
 {
-    {
-        toml::table v{{"num", 42}};
-        BOOST_CHECK_EQUAL(42, toml::get_or<int>(v, "num", 0));
-        BOOST_CHECK_EQUAL(0,  toml::get_or<int>(v, "foo", 0));
-    }
-    {
-        toml::value v = toml::table{{"num", 42}};
-        BOOST_CHECK_EQUAL(42, toml::get_or<int>(v, "num", 0));
-        BOOST_CHECK_EQUAL(0,  toml::get_or<int>(v, "foo", 0));
-    }
+    // requires conversion int -> uint
     {
         toml::value v1(42);
         toml::value v2(3.14);
-        BOOST_CHECK_EQUAL(42, toml::get_or<int>(v1, 0));
-        BOOST_CHECK_EQUAL(0,  toml::get_or<int>(v2, 0));
+        BOOST_CHECK_EQUAL(42u, toml::get_or(v1, 0u));
+        BOOST_CHECK_EQUAL(0u,  toml::get_or(v2, 0u));
+    }
+
+    // exact toml type
+    {
+        toml::value v1(42);
+        toml::value v2(3.14);
+
+        toml::integer opt(0);
+        BOOST_CHECK_EQUAL(42, toml::get_or(v1, opt));
+        BOOST_CHECK_EQUAL(0,  toml::get_or(v2, opt));
+
+        toml::value v3("foobar");
+        toml::string s("bazqux");
+
+        BOOST_CHECK_EQUAL("foobar", toml::get_or(v3, s));
+        BOOST_CHECK_EQUAL("bazqux", toml::get_or(v1, s));
+
+    }
+
+    // std::string
+    {
+        toml::value v1("foobar");
+        toml::value v2(42);
+
+        std::string       s1("bazqux");
+        const std::string s2("bazqux");
+
+        BOOST_CHECK_EQUAL("foobar", toml::get_or(v1, s1));
+        BOOST_CHECK_EQUAL("bazqux", toml::get_or(v2, s1));
+
+        std::string& v1r = toml::get_or(v1, s1);
+        std::string& s1r = toml::get_or(v2, s1);
+
+        BOOST_CHECK_EQUAL("foobar", v1r);
+        BOOST_CHECK_EQUAL("bazqux", s1r);
+
+        BOOST_CHECK_EQUAL("foobar", toml::get_or(v1, s2));
+        BOOST_CHECK_EQUAL("bazqux", toml::get_or(v2, s2));
+
+        BOOST_CHECK_EQUAL("foobar", toml::get_or(v1, std::move(s1)));
+        BOOST_CHECK_EQUAL("bazqux", toml::get_or(v2, std::move(s1)));
+    }
+
+    // string literal
+    {
+        toml::value v1("foobar");
+        toml::value v2(42);
+
+        BOOST_CHECK_EQUAL("foobar", toml::get_or(v1, "bazqux"));
+        BOOST_CHECK_EQUAL("bazqux", toml::get_or(v2, "bazqux"));
+
+        const char* lit = "bazqux";
+        BOOST_CHECK_EQUAL("foobar", toml::get_or(v1, lit));
+        BOOST_CHECK_EQUAL("bazqux", toml::get_or(v2, lit));
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_find_or)
+{
+    // ========================================================================
+    // pass toml::value
+    //
+    // requires conversion int -> uint
+    {
+        toml::table v{{"num", 42}};
+        BOOST_CHECK_EQUAL(42u, toml::find_or(v, "num", 0u));
+        BOOST_CHECK_EQUAL(0u,  toml::find_or(v, "foo", 0u));
+    }
+    // exact toml type
+    {
+        toml::table v1{{"key", 42  }};
+        toml::table v2{{"key", 3.14}};
+        toml::table v3{{"not", "key"}};
+
+        toml::integer opt(0);
+        BOOST_CHECK_EQUAL(42, toml::find_or(v1, "key", opt));
+        BOOST_CHECK_EQUAL(0,  toml::find_or(v2, "key", opt));
+        BOOST_CHECK_EQUAL(0,  toml::find_or(v3, "key", opt));
+
+        toml::table v4{{"str", "foobar"}};
+        toml::string s("bazqux");
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v4, "str", s));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v1, "str", s));
+    }
+    // std::string
+    {
+        toml::table v1{{"key", "foobar"}};
+        toml::table v2{{"key", 42}};
+
+        std::string       s1("bazqux");
+        const std::string s2("bazqux");
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", s1));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", s1));
+
+        std::string& v1r = toml::find_or(v1, "key", s1);
+        std::string& s1r = toml::find_or(v2, "key", s1);
+
+        BOOST_CHECK_EQUAL("foobar", v1r);
+        BOOST_CHECK_EQUAL("bazqux", s1r);
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", s2));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", s2));
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(std::move(v1), "key", std::move(s1)));
+        s1 = "bazqux"; // restoring moved value
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(std::move(v2), "key", std::move(s1)));
+    }
+    // string literal
+    {
+        toml::table v1{{"key", "foobar"}};
+        toml::table v2{{"key",42}};
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", "bazqux"));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", "bazqux"));
+
+        const char* lit = "bazqux";
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", lit));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", lit));
+    }
+
+    // ========================================================================
+    // pass toml::value
+    //
+    // requires conversion int -> uint
+    {
+        toml::table v = toml::table{{"num", 42}};
+        BOOST_CHECK_EQUAL(42u, toml::find_or(v, "num", 0u));
+        BOOST_CHECK_EQUAL(0u,  toml::find_or(v, "foo", 0u));
+    }
+    // exact toml type
+    {
+        toml::value v1 = toml::table{{"key", 42  }};
+        toml::value v2 = toml::table{{"key", 3.14}};
+        toml::value v3 = toml::table{{"not", "key"}};
+
+        BOOST_CHECK_EQUAL(42, toml::find_or(v1, "key", toml::integer(0)));
+        BOOST_CHECK_EQUAL( 0, toml::find_or(v2, "key", toml::integer(0)));
+        BOOST_CHECK_EQUAL( 0, toml::find_or(v3, "key", toml::integer(0)));
+
+        toml::value v4 = toml::table{{"str", "foobar"}};
+        toml::string s("bazqux");
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v4, "str", s));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v1, "str", s));
+    }
+    // std::string
+    {
+        toml::value v1 = toml::table{{"key", "foobar"}};
+        toml::value v2 = toml::table{{"key", 42}};
+
+        std::string       s1("bazqux");
+        const std::string s2("bazqux");
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", s1));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", s1));
+
+        std::string& v1r = toml::find_or(v1, "key", s1);
+        std::string& s1r = toml::find_or(v2, "key", s1);
+
+        BOOST_CHECK_EQUAL("foobar", v1r);
+        BOOST_CHECK_EQUAL("bazqux", s1r);
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", s2));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", s2));
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(std::move(v1), "key", std::move(s1)));
+        s1 = "bazqux"; // restoring moved value
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(std::move(v2), "key", std::move(s1)));
+    }
+    // string literal
+    {
+        toml::value v1 = toml::table{{"key", "foobar"}};
+        toml::value v2 = toml::table{{"key",42}};
+
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", "bazqux"));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", "bazqux"));
+
+        const char* lit = "bazqux";
+        BOOST_CHECK_EQUAL("foobar", toml::find_or(v1, "key", lit));
+        BOOST_CHECK_EQUAL("bazqux", toml::find_or(v2, "key", lit));
     }
 }
 

tests/test_literals.cpp

@@ -0,0 +1,129 @@
+#define BOOST_TEST_MODULE "test_literals"
+#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
+#include <boost/test/unit_test.hpp>
+#else
+#define BOOST_TEST_NO_LIB
+#include <boost/test/included/unit_test.hpp>
+#endif
+#include <toml.hpp>
+#include <map>
+
+BOOST_AUTO_TEST_CASE(test_file_as_literal)
+{
+    using namespace toml::literals::toml_literals;
+
+    {
+        const toml::value r{{"a", 42}, {"b", "baz"}};
+        const toml::value v = u8R"(
+            a = 42
+            b = "baz"
+        )"_toml;
+
+        BOOST_CHECK_EQUAL(r, v);
+    }
+    {
+        const toml::value r{
+            {"c", 3.14},
+            {"table", toml::table{{"a", 42}, {"b", "baz"}}}
+        };
+        const toml::value v = u8R"(
+            c = 3.14
+            [table]
+            a = 42
+            b = "baz"
+        )"_toml;
+
+        BOOST_CHECK_EQUAL(r, v);
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_value_as_literal)
+{
+    using namespace toml::literals::toml_literals;
+
+    {
+        const toml::value v1 = u8"true"_toml;
+        const toml::value v2 = u8"false"_toml;
+
+        BOOST_CHECK(v1.is_boolean());
+        BOOST_CHECK(v2.is_boolean());
+        BOOST_CHECK(toml::get<bool>(v1));
+        BOOST_CHECK(!toml::get<bool>(v2));
+    }
+    {
+        const toml::value v1 = u8"123_456"_toml;
+        const toml::value v2 = u8"0b0010"_toml;
+        const toml::value v3 = u8"0xDEADBEEF"_toml;
+
+        BOOST_CHECK(v1.is_integer());
+        BOOST_CHECK(v2.is_integer());
+        BOOST_CHECK(v3.is_integer());
+        BOOST_CHECK_EQUAL(toml::get<toml::integer>(v1), 123456);
+        BOOST_CHECK_EQUAL(toml::get<toml::integer>(v2), 2);
+        BOOST_CHECK_EQUAL(toml::get<toml::integer>(v3), 0xDEADBEEF);
+    }
+    {
+        const toml::value v1 = u8"3.1415"_toml;
+        const toml::value v2 = u8"6.02e+23"_toml;
+
+        BOOST_CHECK(v1.is_float());
+        BOOST_CHECK(v2.is_float());
+        BOOST_CHECK_CLOSE(toml::get<double>(v1), 3.1415,  0.00001);
+        BOOST_CHECK_CLOSE(toml::get<double>(v2), 6.02e23, 0.0001);
+    }
+    {
+        const toml::value v1 = u8R"("foo")"_toml;
+        const toml::value v2 = u8R"('foo')"_toml;
+        const toml::value v3 = u8R"("""foo""")"_toml;
+        const toml::value v4 = u8R"('''foo''')"_toml;
+
+        BOOST_CHECK(v1.is_string());
+        BOOST_CHECK(v2.is_string());
+        BOOST_CHECK(v3.is_string());
+        BOOST_CHECK(v4.is_string());
+        BOOST_CHECK_EQUAL(toml::get<std::string>(v1), "foo");
+        BOOST_CHECK_EQUAL(toml::get<std::string>(v2), "foo");
+        BOOST_CHECK_EQUAL(toml::get<std::string>(v3), "foo");
+        BOOST_CHECK_EQUAL(toml::get<std::string>(v4), "foo");
+    }
+    {
+        const toml::value v1 = u8R"([1,2,3])"_toml;
+
+        BOOST_CHECK(v1.is_array());
+        BOOST_CHECK((toml::get<std::vector<int>>(v1) == std::vector<int>{1,2,3}));
+    }
+    {
+        const toml::value v1 = u8R"({a = 42})"_toml;
+
+        BOOST_CHECK(v1.is_table());
+        BOOST_CHECK((toml::get<std::map<std::string,int>>(v1) ==
+                               std::map<std::string,int>{{"a", 42}}));
+    }
+    {
+        const toml::value v1 = u8"1979-05-27"_toml;
+
+        BOOST_CHECK(v1.is_local_date());
+        BOOST_CHECK_EQUAL(toml::get<toml::local_date>(v1),
+                          toml::local_date(1979, toml::month_t::May, 27));
+    }
+    {
+        const toml::value v1 = u8"12:00:00"_toml;
+
+        BOOST_CHECK(v1.is_local_time());
+        BOOST_CHECK(toml::get<std::chrono::hours>(v1) == std::chrono::hours(12));
+    }
+    {
+        const toml::value v1 = u8"1979-05-27T07:32:00"_toml;
+        BOOST_CHECK(v1.is_local_datetime());
+        BOOST_CHECK_EQUAL(toml::get<toml::local_datetime>(v1),
+            toml::local_datetime(toml::local_date(1979, toml::month_t::May, 27),
+                                 toml::local_time(7, 32, 0)));
+    }
+    {
+        const toml::value v1 = "1979-05-27T07:32:00Z"_toml;
+        BOOST_CHECK(v1.is_offset_datetime());
+        BOOST_CHECK_EQUAL(toml::get<toml::offset_datetime>(v1),
+            toml::offset_datetime(toml::local_date(1979, toml::month_t::May, 27),
+                                  toml::local_time(7, 32, 0), toml::time_offset(0, 0)));
+    }
+}

tests/test_multiple_translation_unit_1.cpp

@@ -0,0 +1,11 @@
+#include <toml.hpp>
+
+int read_a(const toml::table&);
+
+int main()
+{
+    const std::string content("a = 0");
+    std::istringstream iss(content);
+    const auto data = toml::parse(iss, "test_multiple_translation_unit.toml");
+    return read_a(data);
+}

tests/test_multiple_translation_unit_2.cpp

@@ -0,0 +1,6 @@
+#include <toml.hpp>
+
+int read_a(const toml::table& t)
+{
+    return toml::get<int>(t.at("a"));
+}

tests/test_parse_file.cpp

@@ -194,3 +194,504 @@ BOOST_AUTO_TEST_CASE(test_hard_example)
     BOOST_CHECK(toml::get<std::vector<std::string>>(bit.at("multi_line_array")) ==
                 expected_multi_line_array);
 }
+
+// ---------------------------------------------------------------------------
+// after here, the test codes generate the content of a file.
+
+BOOST_AUTO_TEST_CASE(test_file_with_BOM)
+{
+    {
+        const std::string table(
+            "\xEF\xBB\xBF" // BOM
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss, "test_file_with_BOM.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "\xEF\xBB\xBF" // BOM
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            );
+        {
+            std::ofstream ofs("tmp.toml");
+            ofs << table;
+        }
+        const auto data = toml::parse("tmp.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "\xEF\xBB\xBF" // BOM
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss, "test_file_with_BOM_CRLF.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "\xEF\xBB\xBF" // BOM
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            );
+        {
+            // with text-mode, "\n" is converted to "\r\n" and the resulting
+            // value will be "\r\r\n". To avoid the additional "\r", use binary
+            // mode.
+            std::ofstream ofs("tmp.toml", std::ios_base::binary);
+            ofs.write(table.data(), table.size());
+        }
+        const auto data = toml::parse("tmp.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_file_without_newline_at_the_end_of_file)
+{
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\""
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\""
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_CRLF.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\" # comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\" # comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\" \t"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_ws.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\" \t"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_ws.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}
+
+
+BOOST_AUTO_TEST_CASE(test_files_end_with_comment)
+{
+    // comment w/o newline
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment\n"
+            "# one more comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // comment w/ newline
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment\n"
+            "# one more comment\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // CRLF version
+
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment\r\n"
+            "# one more comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment\r\n"
+            "# one more comment\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}
+
+
+BOOST_AUTO_TEST_CASE(test_files_end_with_empty_lines)
+{
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "\n"
+            "\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // with whitespaces
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  \n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  \n"
+            "  \n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "\n"
+            "  \n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  \n"
+            "\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // with whitespaces but no newline
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  "
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+
+    // CRLF
+
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "\r\n"
+            "\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // with whitespaces
+
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  \r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "\r\n"
+            "  \r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  \r\n"
+            "\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  \r\n"
+            "  \r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  "
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}

tests/test_parse_key.cpp

@@ -13,23 +13,23 @@ using namespace detail;
 
 BOOST_AUTO_TEST_CASE(test_bare_key)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "barekey",  std::vector<key>(1, "barekey"));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "bare-key", std::vector<key>(1, "bare-key"));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "bare_key", std::vector<key>(1, "bare_key"));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "1234",     std::vector<key>(1, "1234"));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "barekey",  std::vector<key>(1, "barekey"));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "bare-key", std::vector<key>(1, "bare-key"));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "bare_key", std::vector<key>(1, "bare_key"));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "1234",     std::vector<key>(1, "1234"));
 }
 
 BOOST_AUTO_TEST_CASE(test_quoted_key)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "\"127.0.0.1\"",          std::vector<key>(1, "127.0.0.1"         ));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "\"character encoding\"", std::vector<key>(1, "character encoding"));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "\"127.0.0.1\"",          std::vector<key>(1, "127.0.0.1"         ));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "\"character encoding\"", std::vector<key>(1, "character encoding"));
 #if defined(_MSC_VER) || defined(__INTEL_COMPILER)
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "\"\xCA\x8E\xC7\x9D\xCA\x9E\"", std::vector<key>(1, "\xCA\x8E\xC7\x9D\xCA\x9E"));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "\"\xCA\x8E\xC7\x9D\xCA\x9E\"", std::vector<key>(1, "\xCA\x8E\xC7\x9D\xCA\x9E"));
 #else
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "\"ʎǝʞ\"",                std::vector<key>(1, "ʎǝʞ"               ));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "\"ʎǝʞ\"",                std::vector<key>(1, "ʎǝʞ"               ));
 #endif
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "'key2'",                 std::vector<key>(1, "key2"              ));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "'quoted \"value\"'",     std::vector<key>(1, "quoted \"value\""  ));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "'key2'",                 std::vector<key>(1, "key2"              ));
+    TOML11_TEST_PARSE_EQUAL(parse_key, "'quoted \"value\"'",     std::vector<key>(1, "quoted \"value\""  ));
 }
 
 BOOST_AUTO_TEST_CASE(test_dotted_key)
@@ -38,13 +38,13 @@ BOOST_AUTO_TEST_CASE(test_dotted_key)
         std::vector<key> keys(2);
         keys[0] = "physical";
         keys[1] = "color";
-        TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "physical.color", keys);
+        TOML11_TEST_PARSE_EQUAL(parse_key, "physical.color", keys);
     }
     {
         std::vector<key> keys(2);
         keys[0] = "physical";
         keys[1] = "shape";
-        TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "physical.shape", keys);
+        TOML11_TEST_PARSE_EQUAL(parse_key, "physical.shape", keys);
     }
     {
         std::vector<key> keys(4);
@@ -52,12 +52,12 @@ BOOST_AUTO_TEST_CASE(test_dotted_key)
         keys[1] = "y";
         keys[2] = "z";
         keys[3] = "w";
-        TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "x.y.z.w", keys);
+        TOML11_TEST_PARSE_EQUAL(parse_key, "x.y.z.w", keys);
     }
     {
         std::vector<key> keys(2);
         keys[0] = "site";
         keys[1] = "google.com";
-        TOML11_TEST_PARSE_EQUAL_VALUE(parse_key, "site.\"google.com\"", keys);
+        TOML11_TEST_PARSE_EQUAL(parse_key, "site.\"google.com\"", keys);
     }
 }

tests/test_serialize_file.cpp

@@ -0,0 +1,54 @@
+#define BOOST_TEST_MODULE "test_serialize_file"
+#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
+#include <boost/test/unit_test.hpp>
+#else
+#define BOOST_TEST_NO_LIB
+#include <boost/test/included/unit_test.hpp>
+#endif
+#include <toml.hpp>
+#include <iostream>
+#include <fstream>
+
+
+BOOST_AUTO_TEST_CASE(test_example)
+{
+    const auto data = toml::parse("toml/tests/example.toml");
+    {
+        std::ofstream ofs("tmp1.toml");
+        ofs << std::setw(80) << data;
+    }
+
+    auto serialized = toml::parse("tmp1.toml");
+    {
+        auto& owner = toml::get<toml::table>(serialized.at("owner"));
+        auto& bio   = toml::get<std::string>(owner.at("bio"));
+        const auto CR = std::find(bio.begin(), bio.end(), '\r');
+        if(CR != bio.end())
+        {
+            bio.erase(CR);
+        }
+    }
+    BOOST_CHECK(data == serialized);
+}
+
+BOOST_AUTO_TEST_CASE(test_fruit)
+{
+    const auto data = toml::parse("toml/tests/fruit.toml");
+    {
+        std::ofstream ofs("tmp2.toml");
+        ofs << std::setw(80) << data;
+    }
+    const auto serialized = toml::parse("tmp2.toml");
+    BOOST_CHECK(data == serialized);
+}
+
+BOOST_AUTO_TEST_CASE(test_hard_example)
+{
+    const auto data = toml::parse("toml/tests/hard_example.toml");
+    {
+        std::ofstream ofs("tmp3.toml");
+        ofs << std::setw(80) << data;
+    }
+    const auto serialized = toml::parse("tmp3.toml");
+    BOOST_CHECK(data == serialized);
+}

tests/test_to_toml.cpp

@@ -1,189 +0,0 @@
-#define BOOST_TEST_MODULE "test_to_toml"
-#ifdef UNITTEST_FRAMEWORK_LIBRARY_EXIST
-#include <boost/test/unit_test.hpp>
-#else
-#define BOOST_TEST_NO_LIB
-#include <boost/test/included/unit_test.hpp>
-#endif
-#include <toml.hpp>
-#include <map>
-#include <list>
-
-BOOST_AUTO_TEST_CASE(test_value_boolean)
-{
-    toml::value v1 = toml::to_toml(true);
-    toml::value v2 = toml::to_toml(false);
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
-    BOOST_CHECK_EQUAL(v2.type(), toml::value_t::Boolean);
-    BOOST_CHECK(v1.is(toml::value_t::Boolean));
-    BOOST_CHECK(v2.is(toml::value_t::Boolean));
-    BOOST_CHECK(v1.is<toml::Boolean>());
-    BOOST_CHECK(v2.is<toml::Boolean>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Boolean>(), false);
-}
-
-BOOST_AUTO_TEST_CASE(test_value_integer)
-{
-    toml::value v1 = toml::to_toml(-42);
-    toml::value v2 = toml::to_toml(42u);
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Integer);
-    BOOST_CHECK_EQUAL(v2.type(), toml::value_t::Integer);
-    BOOST_CHECK(v1.is(toml::value_t::Integer));
-    BOOST_CHECK(v2.is(toml::value_t::Integer));
-    BOOST_CHECK(v1.is<toml::Integer>());
-    BOOST_CHECK(v2.is<toml::Integer>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Integer>(), -42);
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Integer>(),  42u);
-}
-
-BOOST_AUTO_TEST_CASE(test_value_float)
-{
-    toml::value v1 = toml::to_toml(3.14);
-    toml::value v2 = toml::to_toml(3.14f);
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Float);
-    BOOST_CHECK_EQUAL(v2.type(), toml::value_t::Float);
-    BOOST_CHECK(v1.is(toml::value_t::Float));
-    BOOST_CHECK(v2.is(toml::value_t::Float));
-    BOOST_CHECK(v1.is<toml::Float>());
-    BOOST_CHECK(v2.is<toml::Float>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Float>(), 3.14);
-    BOOST_CHECK_CLOSE_FRACTION(v2.cast<toml::value_t::Float>(), 3.14, 1e-2);
-}
-
-BOOST_AUTO_TEST_CASE(test_value_string)
-{
-    toml::value v1 = toml::to_toml(std::string("foo"));
-    toml::value v2 = toml::to_toml(std::string("foo"), toml::string_t::literal);
-    toml::value v3 = toml::to_toml("foo");
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::String);
-    BOOST_CHECK_EQUAL(v2.type(), toml::value_t::String);
-    BOOST_CHECK_EQUAL(v3.type(), toml::value_t::String);
-    BOOST_CHECK(v1.is(toml::value_t::String));
-    BOOST_CHECK(v2.is(toml::value_t::String));
-    BOOST_CHECK(v3.is(toml::value_t::String));
-    BOOST_CHECK(v1.is<toml::String>());
-    BOOST_CHECK(v2.is<toml::String>());
-    BOOST_CHECK(v3.is<toml::String>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::String>(), "foo");
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::String>(), "foo");
-    BOOST_CHECK_EQUAL(v3.cast<toml::value_t::String>(), "foo");
-}
-
-BOOST_AUTO_TEST_CASE(test_value_local_date)
-{
-    toml::value v1 = toml::to_toml(toml::local_date(2018, toml::month_t::Jan, 31));
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalDate);
-    BOOST_CHECK(v1.is(toml::value_t::LocalDate));
-    BOOST_CHECK(v1.is<toml::LocalDate>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalDate>(),
-                      toml::local_date(2018, toml::month_t::Jan, 31));
-}
-
-BOOST_AUTO_TEST_CASE(test_value_local_time)
-{
-    toml::value v1 = toml::to_toml(toml::local_time(12, 30, 45));
-    toml::value v2 = toml::to_toml(std::chrono::hours(12) + std::chrono::minutes(30) +
-                   std::chrono::seconds(45));
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalTime);
-    BOOST_CHECK_EQUAL(v2.type(), toml::value_t::LocalTime);
-    BOOST_CHECK(v1.is(toml::value_t::LocalTime));
-    BOOST_CHECK(v2.is(toml::value_t::LocalTime));
-    BOOST_CHECK(v1.is<toml::LocalTime>());
-    BOOST_CHECK(v2.is<toml::LocalTime>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalTime>(),
-                      toml::local_time(12, 30, 45));
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::LocalTime>(),
-                      toml::local_time(12, 30, 45));
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalTime>(),
-                      v2.cast<toml::value_t::LocalTime>());
-}
-
-BOOST_AUTO_TEST_CASE(test_value_local_datetime)
-{
-    toml::value v1 = toml::to_toml(toml::local_datetime(
-                toml::local_date(2018, toml::month_t::Jan, 31),
-                toml::local_time(12, 30, 45)
-                ));
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalDatetime);
-    BOOST_CHECK(v1.is(toml::value_t::LocalDatetime));
-    BOOST_CHECK(v1.is<toml::LocalDatetime>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalDatetime>(),
-                      toml::local_datetime(
-                          toml::local_date(2018, toml::month_t::Jan, 31),
-                          toml::local_time(12, 30, 45)));
-}
-
-BOOST_AUTO_TEST_CASE(test_value_offset_datetime)
-{
-    toml::value v1 = toml::to_toml(toml::offset_datetime(
-                toml::local_date(2018, toml::month_t::Jan, 31),
-                toml::local_time(12, 30, 45),
-                toml::time_offset(9, 0)
-                ));
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::OffsetDatetime);
-    BOOST_CHECK(v1.is(toml::value_t::OffsetDatetime));
-    BOOST_CHECK(v1.is<toml::OffsetDatetime>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::OffsetDatetime>(),
-            toml::offset_datetime(
-                toml::local_date(2018, toml::month_t::Jan, 31),
-                toml::local_time(12, 30, 45),
-                toml::time_offset(9, 0)
-                ));
-}
-
-BOOST_AUTO_TEST_CASE(test_value_array)
-{
-    std::vector<int> v{1,2,3,4,5};
-    toml::value v1 = toml::to_toml(v);
-    toml::value v2 = toml::to_toml(6,7,8,9,0);
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Array);
-    BOOST_CHECK(v1.is(toml::value_t::Array));
-    BOOST_CHECK(v1.is<toml::Array>());
-
-    BOOST_CHECK_EQUAL(v2.type(), toml::value_t::Array);
-    BOOST_CHECK(v2.is(toml::value_t::Array));
-    BOOST_CHECK(v2.is<toml::Array>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(0).cast<toml::value_t::Integer>(), 1);
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(1).cast<toml::value_t::Integer>(), 2);
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(2).cast<toml::value_t::Integer>(), 3);
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(3).cast<toml::value_t::Integer>(), 4);
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(4).cast<toml::value_t::Integer>(), 5);
-
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Array>().at(0).cast<toml::value_t::Integer>(), 6);
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Array>().at(1).cast<toml::value_t::Integer>(), 7);
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Array>().at(2).cast<toml::value_t::Integer>(), 8);
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Array>().at(3).cast<toml::value_t::Integer>(), 9);
-    BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Array>().at(4).cast<toml::value_t::Integer>(), 0);
-}
-
-BOOST_AUTO_TEST_CASE(test_value_table)
-{
-    toml::value v1 = toml::to_toml({{"foo", 42}, {"bar", 3.14}, {"baz", "qux"}});
-
-    BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Table);
-    BOOST_CHECK(v1.is(toml::value_t::Table));
-    BOOST_CHECK(v1.is<toml::Table>());
-
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("foo").cast<toml::value_t::Integer>(),    42);
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("bar").cast<toml::value_t::Float>(),      3.14);
-    BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("baz").cast<toml::value_t::String>().str, "qux");
-}

tests/test_value.cpp

@@ -20,6 +20,8 @@ BOOST_AUTO_TEST_CASE(test_value_boolean)
     BOOST_CHECK(v2.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
     BOOST_CHECK(v2.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
+    BOOST_CHECK(v2.is_boolean());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Boolean>(), false);
@@ -33,6 +35,8 @@ BOOST_AUTO_TEST_CASE(test_value_boolean)
     BOOST_CHECK(v2.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
     BOOST_CHECK(v2.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
+    BOOST_CHECK(v2.is_boolean());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), false);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Boolean>(), true);
@@ -48,6 +52,8 @@ BOOST_AUTO_TEST_CASE(test_value_boolean)
     BOOST_CHECK(v4.is(toml::value_t::Boolean));
     BOOST_CHECK(v3.is<toml::Boolean>());
     BOOST_CHECK(v4.is<toml::Boolean>());
+    BOOST_CHECK(v3.is_boolean());
+    BOOST_CHECK(v4.is_boolean());
 
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::Boolean>(), false);
     BOOST_CHECK_EQUAL(v4.cast<toml::value_t::Boolean>(), true);
@@ -61,6 +67,8 @@ BOOST_AUTO_TEST_CASE(test_value_boolean)
     BOOST_CHECK(v6.is(toml::value_t::Boolean));
     BOOST_CHECK(v5.is<toml::Boolean>());
     BOOST_CHECK(v6.is<toml::Boolean>());
+    BOOST_CHECK(v3.is_boolean());
+    BOOST_CHECK(v4.is_boolean());
 
     BOOST_CHECK_EQUAL(v5.cast<toml::value_t::Boolean>(), false);
     BOOST_CHECK_EQUAL(v6.cast<toml::value_t::Boolean>(), true);
@@ -74,6 +82,8 @@ BOOST_AUTO_TEST_CASE(test_value_boolean)
     BOOST_CHECK(v2.is(toml::value_t::Float));
     BOOST_CHECK(v1.is<toml::Integer>());
     BOOST_CHECK(v2.is<toml::Float>());
+    BOOST_CHECK(v1.is_integer());
+    BOOST_CHECK(v2.is_float());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Integer>(), 42);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Float>(),   3.14);
@@ -90,6 +100,8 @@ BOOST_AUTO_TEST_CASE(test_value_integer)
     BOOST_CHECK(v2.is(toml::value_t::Integer));
     BOOST_CHECK(v1.is<toml::Integer>());
     BOOST_CHECK(v2.is<toml::Integer>());
+    BOOST_CHECK(v1.is_integer());
+    BOOST_CHECK(v2.is_integer());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Integer>(), -42);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Integer>(),  42u);
@@ -103,6 +115,8 @@ BOOST_AUTO_TEST_CASE(test_value_integer)
     BOOST_CHECK(v2.is(toml::value_t::Integer));
     BOOST_CHECK(v1.is<toml::Integer>());
     BOOST_CHECK(v2.is<toml::Integer>());
+    BOOST_CHECK(v1.is_integer());
+    BOOST_CHECK(v2.is_integer());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Integer>(),  54);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Integer>(), -54);
@@ -118,6 +132,8 @@ BOOST_AUTO_TEST_CASE(test_value_integer)
     BOOST_CHECK(v4.is(toml::value_t::Integer));
     BOOST_CHECK(v3.is<toml::Integer>());
     BOOST_CHECK(v4.is<toml::Integer>());
+    BOOST_CHECK(v3.is_integer());
+    BOOST_CHECK(v4.is_integer());
 
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::Integer>(),  54);
     BOOST_CHECK_EQUAL(v4.cast<toml::value_t::Integer>(), -54);
@@ -131,6 +147,8 @@ BOOST_AUTO_TEST_CASE(test_value_integer)
     BOOST_CHECK(v6.is(toml::value_t::Integer));
     BOOST_CHECK(v5.is<toml::Integer>());
     BOOST_CHECK(v6.is<toml::Integer>());
+    BOOST_CHECK(v5.is_integer());
+    BOOST_CHECK(v6.is_integer());
 
     BOOST_CHECK_EQUAL(v5.cast<toml::value_t::Integer>(),  54);
     BOOST_CHECK_EQUAL(v6.cast<toml::value_t::Integer>(), -54);
@@ -144,6 +162,8 @@ BOOST_AUTO_TEST_CASE(test_value_integer)
     BOOST_CHECK(v2.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
     BOOST_CHECK(v2.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
+    BOOST_CHECK(v2.is_boolean());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Boolean>(), false);
@@ -160,6 +180,8 @@ BOOST_AUTO_TEST_CASE(test_value_float)
     BOOST_CHECK(v2.is(toml::value_t::Float));
     BOOST_CHECK(v1.is<toml::Float>());
     BOOST_CHECK(v2.is<toml::Float>());
+    BOOST_CHECK(v1.is_float());
+    BOOST_CHECK(v2.is_float());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Float>(), 3.14);
     BOOST_CHECK_CLOSE_FRACTION(v2.cast<toml::value_t::Float>(), 3.14, 1e-2);
@@ -173,6 +195,8 @@ BOOST_AUTO_TEST_CASE(test_value_float)
     BOOST_CHECK(v2.is(toml::value_t::Float));
     BOOST_CHECK(v1.is<toml::Float>());
     BOOST_CHECK(v2.is<toml::Float>());
+    BOOST_CHECK(v1.is_float());
+    BOOST_CHECK(v2.is_float());
 
     BOOST_CHECK_CLOSE_FRACTION(v1.cast<toml::value_t::Float>(), 2.718, 1e-3);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Float>(), 2.718);
@@ -188,6 +212,8 @@ BOOST_AUTO_TEST_CASE(test_value_float)
     BOOST_CHECK(v4.is(toml::value_t::Float));
     BOOST_CHECK(v3.is<toml::Float>());
     BOOST_CHECK(v4.is<toml::Float>());
+    BOOST_CHECK(v3.is_float());
+    BOOST_CHECK(v4.is_float());
 
     BOOST_CHECK_CLOSE_FRACTION(v3.cast<toml::value_t::Float>(), 2.718, 1e-3);
     BOOST_CHECK_EQUAL(v4.cast<toml::value_t::Float>(), 2.718);
@@ -201,6 +227,8 @@ BOOST_AUTO_TEST_CASE(test_value_float)
     BOOST_CHECK(v6.is(toml::value_t::Float));
     BOOST_CHECK(v5.is<toml::Float>());
     BOOST_CHECK(v6.is<toml::Float>());
+    BOOST_CHECK(v5.is_float());
+    BOOST_CHECK(v6.is_float());
 
     BOOST_CHECK_CLOSE_FRACTION(v5.cast<toml::value_t::Float>(), 2.718, 1e-3);
     BOOST_CHECK_EQUAL(v6.cast<toml::value_t::Float>(), 2.718);
@@ -214,6 +242,8 @@ BOOST_AUTO_TEST_CASE(test_value_float)
     BOOST_CHECK(v2.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
     BOOST_CHECK(v2.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
+    BOOST_CHECK(v2.is_boolean());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Boolean>(), false);
@@ -234,6 +264,9 @@ BOOST_AUTO_TEST_CASE(test_value_string)
     BOOST_CHECK(v1.is<toml::String>());
     BOOST_CHECK(v2.is<toml::String>());
     BOOST_CHECK(v3.is<toml::String>());
+    BOOST_CHECK(v1.is_string());
+    BOOST_CHECK(v2.is_string());
+    BOOST_CHECK(v3.is_string());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::String>(), "foo");
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::String>(), "foo");
@@ -249,9 +282,9 @@ BOOST_AUTO_TEST_CASE(test_value_string)
     BOOST_CHECK(v1.is(toml::value_t::String));
     BOOST_CHECK(v2.is(toml::value_t::String));
     BOOST_CHECK(v3.is(toml::value_t::String));
-    BOOST_CHECK(v1.is<toml::String>());
-    BOOST_CHECK(v2.is<toml::String>());
-    BOOST_CHECK(v3.is<toml::String>());
+    BOOST_CHECK(v1.is_string());
+    BOOST_CHECK(v2.is_string());
+    BOOST_CHECK(v3.is_string());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::String>(), "bar");
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::String>(), "bar");
@@ -273,6 +306,9 @@ BOOST_AUTO_TEST_CASE(test_value_string)
     BOOST_CHECK(v4.is<toml::String>());
     BOOST_CHECK(v5.is<toml::String>());
     BOOST_CHECK(v6.is<toml::String>());
+    BOOST_CHECK(v4.is_string());
+    BOOST_CHECK(v5.is_string());
+    BOOST_CHECK(v6.is_string());
 
     BOOST_CHECK_EQUAL(v4.cast<toml::value_t::String>(), "bar");
     BOOST_CHECK_EQUAL(v5.cast<toml::value_t::String>(), "bar");
@@ -291,6 +327,9 @@ BOOST_AUTO_TEST_CASE(test_value_string)
     BOOST_CHECK(v4.is<toml::String>());
     BOOST_CHECK(v5.is<toml::String>());
     BOOST_CHECK(v6.is<toml::String>());
+    BOOST_CHECK(v4.is_string());
+    BOOST_CHECK(v5.is_string());
+    BOOST_CHECK(v6.is_string());
 
     BOOST_CHECK_EQUAL(v4.cast<toml::value_t::String>(), "baz");
     BOOST_CHECK_EQUAL(v5.cast<toml::value_t::String>(), "baz");
@@ -309,6 +348,9 @@ BOOST_AUTO_TEST_CASE(test_value_string)
     BOOST_CHECK(v1.is<toml::Boolean>());
     BOOST_CHECK(v2.is<toml::Boolean>());
     BOOST_CHECK(v3.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
+    BOOST_CHECK(v2.is_boolean());
+    BOOST_CHECK(v3.is_boolean());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::Boolean>(), true);
@@ -322,6 +364,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_date)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalDate);
     BOOST_CHECK(v1.is(toml::value_t::LocalDate));
     BOOST_CHECK(v1.is<toml::LocalDate>());
+    BOOST_CHECK(v1.is_local_date());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalDate>(),
                       toml::local_date(2018, toml::month_t::Jan, 31));
@@ -331,6 +374,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_date)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalDate);
     BOOST_CHECK(v1.is(toml::value_t::LocalDate));
     BOOST_CHECK(v1.is<toml::LocalDate>());
+    BOOST_CHECK(v1.is_local_date());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalDate>(),
                       toml::local_date(2018, toml::month_t::Apr, 1));
@@ -341,6 +385,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_date)
     BOOST_CHECK_EQUAL(v2.type(), toml::value_t::LocalDate);
     BOOST_CHECK(v2.is(toml::value_t::LocalDate));
     BOOST_CHECK(v2.is<toml::LocalDate>());
+    BOOST_CHECK(v2.is_local_date());
 
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::LocalDate>(),
                       toml::local_date(2018, toml::month_t::Apr, 1));
@@ -349,6 +394,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_date)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
     BOOST_CHECK(v1.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
 }
 
@@ -364,6 +410,8 @@ BOOST_AUTO_TEST_CASE(test_value_local_time)
     BOOST_CHECK(v2.is(toml::value_t::LocalTime));
     BOOST_CHECK(v1.is<toml::LocalTime>());
     BOOST_CHECK(v2.is<toml::LocalTime>());
+    BOOST_CHECK(v1.is_local_time());
+    BOOST_CHECK(v2.is_local_time());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalTime>(),
                       toml::local_time(12, 30, 45));
@@ -377,6 +425,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_time)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalTime);
     BOOST_CHECK(v1.is(toml::value_t::LocalTime));
     BOOST_CHECK(v1.is<toml::LocalTime>());
+    BOOST_CHECK(v1.is_local_time());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalTime>(),
                       toml::local_time(1, 30, 0, 100, 0));
 
@@ -386,6 +435,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_time)
     BOOST_CHECK_EQUAL(v3.type(), toml::value_t::LocalTime);
     BOOST_CHECK(v3.is(toml::value_t::LocalTime));
     BOOST_CHECK(v3.is<toml::LocalTime>());
+    BOOST_CHECK(v3.is_local_time());
 
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::LocalTime>(),
                       toml::local_time(1, 30, 0, 100, 0));
@@ -394,6 +444,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_time)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
     BOOST_CHECK(v1.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
 }
 
@@ -407,6 +458,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_datetime)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalDatetime);
     BOOST_CHECK(v1.is(toml::value_t::LocalDatetime));
     BOOST_CHECK(v1.is<toml::LocalDatetime>());
+    BOOST_CHECK(v1.is_local_datetime());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalDatetime>(),
                       toml::local_datetime(
@@ -420,6 +472,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_datetime)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::LocalDatetime);
     BOOST_CHECK(v1.is(toml::value_t::LocalDatetime));
     BOOST_CHECK(v1.is<toml::LocalDatetime>());
+    BOOST_CHECK(v1.is_local_datetime());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::LocalDatetime>(),
                       toml::local_datetime(
@@ -432,6 +485,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_datetime)
     BOOST_CHECK_EQUAL(v2.type(), toml::value_t::LocalDatetime);
     BOOST_CHECK(v2.is(toml::value_t::LocalDatetime));
     BOOST_CHECK(v2.is<toml::LocalDatetime>());
+    BOOST_CHECK(v2.is_local_datetime());
 
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::LocalDatetime>(),
                       toml::local_datetime(
@@ -442,6 +496,7 @@ BOOST_AUTO_TEST_CASE(test_value_local_datetime)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
     BOOST_CHECK(v1.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
 }
 
@@ -456,6 +511,7 @@ BOOST_AUTO_TEST_CASE(test_value_offset_datetime)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::OffsetDatetime);
     BOOST_CHECK(v1.is(toml::value_t::OffsetDatetime));
     BOOST_CHECK(v1.is<toml::OffsetDatetime>());
+    BOOST_CHECK(v1.is_offset_datetime());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::OffsetDatetime>(),
             toml::offset_datetime(
@@ -472,6 +528,7 @@ BOOST_AUTO_TEST_CASE(test_value_offset_datetime)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::OffsetDatetime);
     BOOST_CHECK(v1.is(toml::value_t::OffsetDatetime));
     BOOST_CHECK(v1.is<toml::OffsetDatetime>());
+    BOOST_CHECK(v1.is_offset_datetime());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::OffsetDatetime>(),
             toml::offset_datetime(
@@ -485,6 +542,7 @@ BOOST_AUTO_TEST_CASE(test_value_offset_datetime)
     BOOST_CHECK_EQUAL(v2.type(), toml::value_t::OffsetDatetime);
     BOOST_CHECK(v2.is(toml::value_t::OffsetDatetime));
     BOOST_CHECK(v2.is<toml::OffsetDatetime>());
+    BOOST_CHECK(v2.is_offset_datetime());
 
     BOOST_CHECK_EQUAL(v2.cast<toml::value_t::OffsetDatetime>(),
             toml::offset_datetime(
@@ -495,6 +553,7 @@ BOOST_AUTO_TEST_CASE(test_value_offset_datetime)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
     BOOST_CHECK(v1.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
 }
 
@@ -507,10 +566,12 @@ BOOST_AUTO_TEST_CASE(test_value_array)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Array);
     BOOST_CHECK(v1.is(toml::value_t::Array));
     BOOST_CHECK(v1.is<toml::Array>());
+    BOOST_CHECK(v1.is_array());
 
     BOOST_CHECK_EQUAL(v2.type(), toml::value_t::Array);
     BOOST_CHECK(v2.is(toml::value_t::Array));
     BOOST_CHECK(v2.is<toml::Array>());
+    BOOST_CHECK(v2.is_array());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(0).cast<toml::value_t::Integer>(), 1);
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(1).cast<toml::value_t::Integer>(), 2);
@@ -530,10 +591,12 @@ BOOST_AUTO_TEST_CASE(test_value_array)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Array);
     BOOST_CHECK(v1.is(toml::value_t::Array));
     BOOST_CHECK(v1.is<toml::Array>());
+    BOOST_CHECK(v1.is_array());
 
     BOOST_CHECK_EQUAL(v2.type(), toml::value_t::Array);
     BOOST_CHECK(v2.is(toml::value_t::Array));
     BOOST_CHECK(v2.is<toml::Array>());
+    BOOST_CHECK(v2.is_array());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(0).cast<toml::value_t::Integer>(), 6);
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Array>().at(1).cast<toml::value_t::Integer>(), 7);
@@ -553,6 +616,7 @@ BOOST_AUTO_TEST_CASE(test_value_array)
     BOOST_CHECK_EQUAL(v3.type(), toml::value_t::Array);
     BOOST_CHECK(v3.is(toml::value_t::Array));
     BOOST_CHECK(v3.is<toml::Array>());
+    BOOST_CHECK(v3.is_array());
 
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::Array>().at(0).cast<toml::value_t::Integer>(), 6);
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::Array>().at(1).cast<toml::value_t::Integer>(), 7);
@@ -564,6 +628,7 @@ BOOST_AUTO_TEST_CASE(test_value_array)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
     BOOST_CHECK(v1.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
 }
 
@@ -574,6 +639,7 @@ BOOST_AUTO_TEST_CASE(test_value_table)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Table);
     BOOST_CHECK(v1.is(toml::value_t::Table));
     BOOST_CHECK(v1.is<toml::Table>());
+    BOOST_CHECK(v1.is_table());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("foo").cast<toml::value_t::Integer>(),    42);
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("bar").cast<toml::value_t::Float>(),      3.14);
@@ -584,6 +650,7 @@ BOOST_AUTO_TEST_CASE(test_value_table)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Table);
     BOOST_CHECK(v1.is(toml::value_t::Table));
     BOOST_CHECK(v1.is<toml::Table>());
+    BOOST_CHECK(v1.is_table());
 
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("foo").cast<toml::value_t::Float>(),      2.71);
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Table>().at("bar").cast<toml::value_t::Integer>(),    54);
@@ -595,6 +662,7 @@ BOOST_AUTO_TEST_CASE(test_value_table)
     BOOST_CHECK_EQUAL(v3.type(), toml::value_t::Table);
     BOOST_CHECK(v3.is(toml::value_t::Table));
     BOOST_CHECK(v3.is<toml::Table>());
+    BOOST_CHECK(v3.is_table());
 
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::Table>().at("foo").cast<toml::value_t::Float>(),      2.71);
     BOOST_CHECK_EQUAL(v3.cast<toml::value_t::Table>().at("bar").cast<toml::value_t::Integer>(),    54);
@@ -604,5 +672,13 @@ BOOST_AUTO_TEST_CASE(test_value_table)
     BOOST_CHECK_EQUAL(v1.type(), toml::value_t::Boolean);
     BOOST_CHECK(v1.is(toml::value_t::Boolean));
     BOOST_CHECK(v1.is<toml::Boolean>());
+    BOOST_CHECK(v1.is_boolean());
     BOOST_CHECK_EQUAL(v1.cast<toml::value_t::Boolean>(), true);
 }
+
+BOOST_AUTO_TEST_CASE(test_value_empty)
+{
+    toml::value v1;
+    BOOST_CHECK(v1.is_uninitialized());
+    BOOST_CHECK(v1.is(toml::value_t::Empty));
+}

toml.hpp

@@ -34,7 +34,8 @@
 #endif
 
 #include "toml/parser.hpp"
-#include "toml/to_toml.hpp"
+#include "toml/literal.hpp"
+#include "toml/serializer.hpp"
 #include "toml/from_toml.hpp"
 #include "toml/get.hpp"
 

toml/combinator.hpp

@@ -39,7 +39,7 @@ inline std::string show_char(const char c)
     else
     {
         std::ostringstream oss;
-        oss << std::hex << std::setfill('0') << std::setw(2) << "0x"
+        oss << "0x" << std::hex << std::setfill('0') << std::setw(2)
             << static_cast<int>(c);
         return oss.str();
     }

toml/datetime.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_DATETIME
-#define TOML11_DATETIME
+#ifndef TOML11_DATETIME_HPP
+#define TOML11_DATETIME_HPP
 #include <chrono>
 #include <tuple>
 #include <array>
@@ -14,6 +14,36 @@
 namespace toml
 {
 
+// To avoid non-threadsafe std::localtime. In C11 (not C++11!), localtime_s is
+// provided in the absolutely same purpose, but C++11 is actually not compatible
+// with C11. We need to dispatch the function depending on the OS.
+namespace detail
+{
+// TODO: find more sophisticated way to handle this
+#if _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE || _SVID_SOURCE || _POSIX_SOURCE
+inline std::tm localtime_s(const std::time_t* src)
+{
+    std::tm dst;
+    const auto result = ::localtime_r(src, &dst);
+    if(!result)
+    {
+        throw std::runtime_error("localtime_r failed.");
+    }
+    return dst;
+}
+#else
+// XXX: On Windows, std::localtime is thread-safe because they uses thread-local
+// storage to store the instance of std::tm. On the other platforms, it may not
+// be thread-safe.
+inline std::tm localtime_s(const std::time_t* src)
+{
+    const auto result = std::localtime(src);
+    if(!result) {throw std::runtime_error("localtime failed.");}
+    return *result;
+}
+#endif
+} // detail
+
 enum class month_t : std::int8_t
 {
     Jan =  0,
@@ -50,10 +80,8 @@ struct local_date
 
     explicit local_date(const std::chrono::system_clock::time_point& tp)
     {
-        const auto t = std::chrono::system_clock::to_time_t(tp);
-        const auto tmp = std::localtime(&t); //XXX: not threadsafe!
-        assert(tmp); // if std::localtime fails, tmp is nullptr
-        const std::tm time = *tmp;
+        const auto t    = std::chrono::system_clock::to_time_t(tp);
+        const auto time = detail::localtime_s(&t);
         *this = local_date(time);
     }
 
@@ -304,17 +332,10 @@ operator<<(std::basic_ostream<charT, traits>& os, const time_offset& offset)
         os << 'Z';
         return os;
     }
-    if(static_cast<int>(offset.hour) * static_cast<int>(offset.minute) < 0)
-    {
-        const int min = static_cast<int>(offset.hour) * 60 + offset.minute;
-        if(min < 0){os << '-';} else {os << '+';}
-        os << std::setfill('0') << std::setw(2) << min / 60 << ':';
-        os << std::setfill('0') << std::setw(2) << min % 60;
-        return os;
-    }
-    if(offset.hour < 0){os << '-';} else {os << '+';}
-    os << std::setfill('0') << std::setw(2) << static_cast<int>(offset.hour) << ':';
-    os << std::setfill('0') << std::setw(2) << static_cast<int>(offset.minute);
+    int minute = static_cast<int>(offset.hour) * 60 + offset.minute;
+    if(minute < 0){os << '-'; minute = std::abs(minute);} else {os << '+';}
+    os << std::setfill('0') << std::setw(2) << minute / 60 << ':';
+    os << std::setfill('0') << std::setw(2) << minute % 60;
     return os;
 }
 
@@ -330,10 +351,8 @@ struct local_datetime
     explicit local_datetime(const std::chrono::system_clock::time_point& tp)
     {
         const auto t = std::chrono::system_clock::to_time_t(tp);
-        const auto tmp = std::localtime(&t); //XXX: not threadsafe!
-        assert(tmp); // if std::localtime fails, tmp is nullptr
+        std::tm time = detail::localtime_s(&t);
 
-        std::tm time = *tmp;
         this->date = local_date(time);
         this->time = local_time(time);
 
@@ -482,10 +501,8 @@ struct offset_datetime
     static time_offset get_local_offset()
     {
          // get current timezone
-        const auto  tmp1 = std::time(nullptr);
-        const auto  tmp2 = std::localtime(&tmp1); // XXX not threadsafe!
-        assert(tmp2);
-        std::tm t = *tmp2;
+        const auto tmp1 = std::time(nullptr);
+        const auto t    = detail::localtime_s(&tmp1);
 
         std::array<char, 6> buf;
         const auto result = std::strftime(buf.data(), 6, "%z", &t); // +hhmm\0

toml/exception.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_EXCEPTION
-#define TOML11_EXCEPTION
+#ifndef TOML11_EXCEPTION_HPP
+#define TOML11_EXCEPTION_HPP
 #include <stdexcept>
 #include <string>
 

toml/from.hpp

@@ -0,0 +1,20 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_FROM_HPP
+#define TOML11_FROM_HPP
+#include "traits.hpp"
+
+namespace toml
+{
+
+template<typename T>
+struct from;
+// {
+//     static T from_toml(const toml::value& v)
+//     {
+//         // User-defined conversions ...
+//     }
+// };
+
+} // toml
+#endif // TOML11_FROM_HPP

toml/from_toml.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_FROM_TOML
-#define TOML11_FROM_TOML
+#ifndef TOML11_FROM_TOML_HPP
+#define TOML11_FROM_TOML_HPP
 #include "get.hpp"
 
 namespace toml

toml/get.hpp

@@ -1,7 +1,8 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_GET
-#define TOML11_GET
+#ifndef TOML11_GET_HPP
+#define TOML11_GET_HPP
+#include "from.hpp"
 #include "result.hpp"
 #include "value.hpp"
 #include <algorithm>
@@ -112,7 +113,7 @@ inline std::string get(value&& v)
 
 template<typename T, typename std::enable_if<
     detail::is_chrono_duration<T>::value, std::nullptr_t>::type = nullptr>
-inline T get(value& v)
+inline T get(const value& v)
 {
     return std::chrono::duration_cast<T>(
             std::chrono::nanoseconds(v.cast<value_t::LocalTime>()));
@@ -124,7 +125,7 @@ inline T get(value& v)
 template<typename T, typename std::enable_if<
     std::is_same<std::chrono::system_clock::time_point, T>::value,
     std::nullptr_t>::type = nullptr>
-inline T get(value& v)
+inline T get(const value& v)
 {
     switch(v.type())
     {
@@ -173,6 +174,20 @@ template<typename T, typename std::enable_if<detail::conjunction<
     >::value, std::nullptr_t>::type = nullptr>
 T get(const toml::value& v);
 
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>>, // not a toml::value
+    detail::has_from_toml_method<T>, // but has from_toml(toml::value) memfn
+    std::is_default_constructible<T> // and default constructible
+    >::value, std::nullptr_t>::type = nullptr>
+T get(const toml::value& v);
+
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>> // not a toml::value
+    >::value, std::nullptr_t>::type = nullptr,
+    std::size_t = sizeof(::toml::from<T>) // and has from<T> specialization
+    >
+T get(const toml::value& v);
+
 // ============================================================================
 // array-like types; most likely STL container, like std::vector, etc.
 
@@ -210,8 +225,9 @@ T get(const value& v)
     {
         throw std::out_of_range(detail::format_underline(concat_to_string(
             "[erorr] toml::get specified container size is ", container.size(),
-            " but there are ", ar.size(), " elements in toml array."),
-            detail::get_region(v), "here"));
+            " but there are ", ar.size(), " elements in toml array."), {
+                {std::addressof(detail::get_region(v)), "here"}
+            }));
     }
     std::transform(ar.cbegin(), ar.cend(), container.begin(),
                    [](const value& x){return ::toml::get<value_type>(x);});
@@ -233,7 +249,9 @@ T get(const value& v)
     {
         throw std::out_of_range(detail::format_underline(concat_to_string(
             "[erorr] toml::get specified std::pair but there are ", ar.size(),
-            " elements in toml array."), detail::get_region(v), "here"));
+            " elements in toml array."), {
+                {std::addressof(detail::get_region(v)), "here"}
+            }));
     }
     return std::make_pair(::toml::get<first_type >(ar.at(0)),
                           ::toml::get<second_type>(ar.at(1)));
@@ -264,7 +282,9 @@ T get(const value& v)
         throw std::out_of_range(detail::format_underline(concat_to_string(
             "[erorr] toml::get specified std::tuple with ",
             std::tuple_size<T>::value, "elements, but there are ", ar.size(),
-            " elements in toml array."), detail::get_region(v), "here"));
+            " elements in toml array."), {
+                {std::addressof(detail::get_region(v)), "here"}
+            }));
     }
     return detail::get_tuple_impl<T>(ar,
             detail::make_index_sequence<std::tuple_size<T>::value>{});
@@ -292,10 +312,33 @@ T get(const toml::value& v)
     return map;
 }
 
+
+// ============================================================================
+// user-defined, but compatible types.
+
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>>, // not a toml::value
+    detail::has_from_toml_method<T>, // but has from_toml(toml::value) memfn
+    std::is_default_constructible<T> // and default constructible
+    >::value, std::nullptr_t>::type>
+T get(const toml::value& v)
+{
+    T ud;
+    ud.from_toml(v);
+    return ud;
+}
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>> // not a toml::value
+    >::value, std::nullptr_t>::type, std::size_t>   // and has from<T>
+T get(const toml::value& v)
+{
+    return ::toml::from<T>::from_toml(v);
+}
+
 // ============================================================================
 // find and get
 
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<const ::toml::value&>()))
 find(const toml::table& tab, const toml::key& ky,
      std::string tablename = "unknown table")
@@ -307,7 +350,7 @@ find(const toml::table& tab, const toml::key& ky,
     }
     return ::toml::get<T>(tab.at(ky));
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&>()))
 find(toml::table& tab, const toml::key& ky,
      std::string tablename = "unknown table")
@@ -319,7 +362,7 @@ find(toml::table& tab, const toml::key& ky,
     }
     return ::toml::get<T>(tab[ky]);
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&&>()))
 find(toml::table&& tab, const toml::key& ky,
      std::string tablename = "unknown table")
@@ -332,7 +375,7 @@ find(toml::table&& tab, const toml::key& ky,
     return ::toml::get<T>(std::move(tab[ky]));
 }
 
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<const ::toml::value&>()))
 find(const toml::value& v, const toml::key& ky)
 {
@@ -340,12 +383,13 @@ find(const toml::value& v, const toml::key& ky)
     if(tab.count(ky) == 0)
     {
         throw std::out_of_range(detail::format_underline(concat_to_string(
-            "[error] key \"", ky, "\" not found"), detail::get_region(v),
-            "in this table"));
+            "[error] key \"", ky, "\" not found"), {
+                {std::addressof(detail::get_region(v)), "in this table"}
+            }));
     }
     return ::toml::get<T>(tab.at(ky));
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&>()))
 find(toml::value& v, const toml::key& ky)
 {
@@ -353,12 +397,13 @@ find(toml::value& v, const toml::key& ky)
     if(tab.count(ky) == 0)
     {
         throw std::out_of_range(detail::format_underline(concat_to_string(
-            "[error] key \"", ky, "\" not found"), detail::get_region(v),
-            "in this table"));
+            "[error] key \"", ky, "\" not found"), {
+                {std::addressof(detail::get_region(v)), "in this table"}
+            }));
     }
     return ::toml::get<T>(tab.at(ky));
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&&>()))
 find(toml::value&& v, const toml::key& ky)
 {
@@ -366,21 +411,23 @@ find(toml::value&& v, const toml::key& ky)
     if(tab.count(ky) == 0)
     {
         throw std::out_of_range(detail::format_underline(concat_to_string(
-            "[error] key \"", ky, "\" not found"), detail::get_region(v),
-            "in this table"));
+            "[error] key \"", ky, "\" not found"), {
+                {std::addressof(detail::get_region(v)), "in this table"}
+            }));
     }
     return ::toml::get<T>(std::move(tab[ky]));
 }
 
 
 // ============================================================================
-// get_or
+// get_or(value, fallback)
 
-template<typename T>
-decltype(::toml::get<typename std::remove_cv<
-            typename std::remove_reference<T>::type>::type>(
-        std::declval<const toml::value&>()))
-get_or(const toml::value& v, T&& opt)
+// ----------------------------------------------------------------------------
+// specialization for the exact toml types (return type becomes lvalue ref)
+
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T const& get_or(const toml::value& v, const T& opt)
 {
     try
     {
@@ -389,14 +436,12 @@ get_or(const toml::value& v, T&& opt)
     }
     catch(...)
     {
-        return std::forward<T>(opt);
+        return opt;
     }
 }
-template<typename T>
-decltype(::toml::get<typename std::remove_cv<
-            typename std::remove_reference<T>::type>::type>(
-        std::declval<toml::value&>()))
-get_or(toml::value& v, T&& opt)
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T& get_or(toml::value& v, T& opt)
 {
     try
     {
@@ -405,77 +450,333 @@ get_or(toml::value& v, T&& opt)
     }
     catch(...)
     {
-        return std::forward<T>(opt);
+        return opt;
     }
 }
-template<typename T>
-decltype(::toml::get<typename std::remove_cv<
-            typename std::remove_reference<T>::type>::type>(
-        std::declval<toml::value&&>()))
-get_or(toml::value&& v, T&& opt)
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T&& get_or(toml::value&& v, T&& opt)
 {
     try
     {
         return get<typename std::remove_cv<
-            typename std::remove_reference<T>::type>::type>(std::move(v));
+            typename std::remove_reference<T>::type>::type>(v);
     }
     catch(...)
     {
-        return std::forward<T>(opt);
+        return opt;
     }
 }
 
+// ----------------------------------------------------------------------------
+// specialization for std::string (return type becomes lvalue ref)
+
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string const& get_or(const toml::value& v, const T& opt)
+{
+    try
+    {
+        return get<std::string>(v);
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string& get_or(toml::value& v, T& opt)
+{
+    try
+    {
+        return get<std::string>(v);
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string get_or(toml::value&& v, T&& opt)
+{
+    try
+    {
+        return get<std::string>(v);
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+template<typename T, typename std::enable_if<
+    detail::is_string_literal<typename std::remove_reference<T>::type>::value,
+    std::nullptr_t>::type = nullptr>
+std::string get_or(const toml::value& v, T&& opt)
+{
+    try
+    {
+        return get<std::string>(v);
+    }
+    catch(...)
+    {
+        return std::string(opt);
+    }
+}
+
+// ----------------------------------------------------------------------------
+// others (require type conversion and return type cannot be lvalue reference)
+
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>>,
+    detail::negation<std::is_same<T, std::string>>,
+    detail::negation<detail::is_string_literal<typename std::remove_reference<T>::type>>
+    >::value, std::nullptr_t>::type = nullptr>
+T get_or(const toml::value& v, T&& opt)
+{
+    try
+    {
+        return get<typename std::remove_cv<
+            typename std::remove_reference<T>::type>::type>(v);
+    }
+    catch(...)
+    {
+        return opt;
+    }
+}
+
+// ===========================================================================
+// get_or(table, key, fallback)
+//
+// DEPRECATED: use find_or instead.
 
 template<typename T>
+TOML11_MARK_AS_DEPRECATED("use toml::find_or(table, key, opt) instead.")
 auto get_or(const toml::table& tab, const toml::key& ky, T&& opt)
     -> decltype(get_or(std::declval<value const&>(), std::forward<T>(opt)))
 {
-    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    if(tab.count(ky) == 0) {return opt;}
     return ::toml::get_or(tab.at(ky), std::forward<T>(opt));
 }
 template<typename T>
+TOML11_MARK_AS_DEPRECATED("use toml::find_or(table, key, opt) instead.")
 auto get_or(toml::table& tab, const toml::key& ky, T&& opt)
     -> decltype(get_or(std::declval<value&>(), std::forward<T>(opt)))
 {
-    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    if(tab.count(ky) == 0) {return opt;}
     return ::toml::get_or(tab[ky], std::forward<T>(opt));
 }
 template<typename T>
+TOML11_MARK_AS_DEPRECATED("use toml::find_or(table, key, opt) instead.")
 auto get_or(toml::table&& tab, const toml::key& ky, T&& opt)
     -> decltype(get_or(std::declval<value&&>(), std::forward<T>(opt)))
 {
-    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    if(tab.count(ky) == 0) {return opt;}
     return ::toml::get_or(std::move(tab[ky]), std::forward<T>(opt));
 }
 
 template<typename T>
+TOML11_MARK_AS_DEPRECATED("use toml::find_or(value, key, opt) instead.")
 auto get_or(const toml::value& v, const toml::key& ky, T&& opt)
     -> decltype(get_or(std::declval<value const&>(), std::forward<T>(opt)))
 {
-    if(v.type() != toml::value_t::Table){return std::forward<T>(opt);}
+    if(!v.is_table()) {return opt;}
     const auto& tab = toml::get<toml::table>(v);
-    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    if(tab.count(ky) == 0) {return opt;}
     return ::toml::get_or(tab.at(ky), std::forward<T>(opt));
 }
 template<typename T>
+TOML11_MARK_AS_DEPRECATED("use toml::find_or(value, key, opt) instead.")
 auto get_or(toml::value& v, const toml::key& ky, T&& opt)
     -> decltype(get_or(std::declval<value&>(), std::forward<T>(opt)))
 {
-    if(v.type() != toml::value_t::Table){return std::forward<T>(opt);}
+    if(!v.is_table()) {return opt;}
     auto& tab = toml::get<toml::table>(v);
-    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    if(tab.count(ky) == 0) {return opt;}
     return ::toml::get_or(tab[ky], std::forward<T>(opt));
 }
 template<typename T>
+TOML11_MARK_AS_DEPRECATED("use toml::find_or(value, key, opt) instead.")
 auto get_or(toml::value&& v, const toml::key& ky, T&& opt)
     -> decltype(get_or(std::declval<value&&>(), std::forward<T>(opt)))
 {
-    if(v.type() != toml::value_t::Table){return std::forward<T>(opt);}
+    if(!v.is_table()) {return opt;}
     auto tab = toml::get<toml::table>(std::move(v));
-    if(tab.count(ky) == 0) {return std::forward<T>(opt);}
+    if(tab.count(ky) == 0) {return opt;}
     return ::toml::get_or(std::move(tab[ky]), std::forward<T>(opt));
 }
 
+// ===========================================================================
+// find_or(value, key, fallback)
+
+// ---------------------------------------------------------------------------
+// exact types (return type can be a reference)
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T const& find_or(const toml::value& v, const toml::key& ky, const T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = toml::get<toml::table>(v);
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T& find_or(toml::value& v, const toml::key& ky, T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto& tab = toml::get<toml::table>(v);
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab[ky], opt);
+}
+
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T&& find_or(toml::value&& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto tab = toml::get<toml::table>(std::move(v));
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(std::move(tab[ky]), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// std::string (return type can be a reference)
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string const& find_or(const toml::value& v, const toml::key& ky, const T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = toml::get<toml::table>(v);
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string& find_or(toml::value& v, const toml::key& ky, T& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto& tab = toml::get<toml::table>(v);
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab[ky], opt);
+}
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string find_or(toml::value&& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return opt;}
+    auto tab = toml::get<toml::table>(std::move(v));
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(std::move(tab[ky]), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// string literal (deduced as std::string)
+template<typename T, typename std::enable_if<
+    detail::is_string_literal<typename std::remove_reference<T>::type>::value,
+    std::nullptr_t>::type = nullptr>
+std::string find_or(const toml::value& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = toml::get<toml::table>(v);
+    if(tab.count(ky) == 0) {return std::string(opt);}
+    return get_or(tab.at(ky), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// others (require type conversion and return type cannot be lvalue reference)
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>>,
+    detail::negation<std::is_same<T, std::string>>,
+    detail::negation<detail::is_string_literal<typename std::remove_reference<T>::type>>
+    >::value, std::nullptr_t>::type = nullptr>
+T find_or(const toml::value& v, const toml::key& ky, T&& opt)
+{
+    if(!v.is_table()) {return opt;}
+    const auto& tab = toml::get<toml::table>(v);
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), std::forward<T>(opt));
+}
+
+// ===========================================================================
+// find_or(table, key, opt)
+
+// ---------------------------------------------------------------------------
+// exact types (return type can be a reference)
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T const& find_or(const toml::table& tab, const toml::key& ky, const T& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T& find_or(toml::table& tab, const toml::key& ky, T& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab[ky], opt);
+}
+
+template<typename T, typename std::enable_if<
+    detail::is_exact_toml_type<T>::value, std::nullptr_t>::type = nullptr>
+T&& find_or(toml::table&& tab, const toml::key& ky, T&& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(std::move(tab[ky]), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// std::string (return type can be a reference)
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string const& find_or(const toml::table& tab, const toml::key& ky, const T& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), opt);
+}
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string& find_or(toml::table& tab, const toml::key& ky, T& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab[ky], opt);
+}
+template<typename T, typename std::enable_if<
+    std::is_same<T, std::string>::value, std::nullptr_t>::type = nullptr>
+std::string find_or(toml::table&& tab, const toml::key& ky, T&& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(std::move(tab[ky]), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// string literal (deduced as std::string)
+template<typename T, typename std::enable_if<
+    detail::is_string_literal<typename std::remove_reference<T>::type>::value,
+    std::nullptr_t>::type = nullptr>
+std::string find_or(const toml::table& tab, const toml::key& ky, T&& opt)
+{
+    if(tab.count(ky) == 0) {return std::string(opt);}
+    return get_or(tab.at(ky), std::forward<T>(opt));
+}
+
+// ---------------------------------------------------------------------------
+// others (require type conversion and return type cannot be lvalue reference)
+template<typename T, typename std::enable_if<detail::conjunction<
+    detail::negation<detail::is_exact_toml_type<T>>,
+    detail::negation<std::is_same<T, std::string>>,
+    detail::negation<detail::is_string_literal<typename std::remove_reference<T>::type>>
+    >::value, std::nullptr_t>::type = nullptr>
+T find_or(const toml::table& tab, const toml::key& ky, T&& opt)
+{
+    if(tab.count(ky) == 0) {return opt;}
+    return get_or(tab.at(ky), std::forward<T>(opt));
+}
+
 // ============================================================================
 // expect
 

toml/into.hpp

@@ -0,0 +1,20 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_INTO_HPP
+#define TOML11_INTO_HPP
+#include "traits.hpp"
+
+namespace toml
+{
+
+template<typename T>
+struct into;
+// {
+//     static toml::value into_toml(const T& user_defined_type)
+//     {
+//         // User-defined conversions ...
+//     }
+// };
+
+} // toml
+#endif // TOML11_INTO_HPP

toml/lexer.hpp

@@ -124,9 +124,9 @@ using lex_escape_unicode_short = sequence<character<'u'>,
 using lex_escape_unicode_long  = sequence<character<'U'>,
                                           repeat<lex_hex_dig, exactly<8>>>;
 using lex_escape_seq_char = either<character<'"'>, character<'\\'>,
-                                   character<'/'>, character<'b'>,
-                                   character<'f'>, character<'n'>,
-                                   character<'r'>, character<'t'>,
+                                   character<'b'>, character<'f'>,
+                                   character<'n'>, character<'r'>,
+                                   character<'t'>,
                                    lex_escape_unicode_short,
                                    lex_escape_unicode_long
                                    >;

toml/literal.hpp

@@ -0,0 +1,55 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_LITERAL_HPP
+#define TOML11_LITERAL_HPP
+#include "parser.hpp"
+
+namespace toml
+{
+inline namespace literals
+{
+inline namespace toml_literals
+{
+
+inline ::toml::value operator""_toml(const char* str, std::size_t len)
+{
+    ::toml::detail::location<std::vector<char>>
+        loc(/* filename = */ std::string("TOML literal encoded in a C++ code"),
+            /* contents = */ std::vector<char>(str, str + len));
+
+    // if there are some comments or empty lines, skip them.
+    using skip_line = ::toml::detail::repeat<toml::detail::sequence<
+            ::toml::detail::maybe<::toml::detail::lex_ws>,
+            ::toml::detail::maybe<::toml::detail::lex_comment>,
+            ::toml::detail::lex_newline
+        >, ::toml::detail::at_least<1>>;
+    skip_line::invoke(loc);
+
+    // if there are some whitespaces before a value, skip them.
+    using skip_ws = ::toml::detail::repeat<
+        ::toml::detail::lex_ws, ::toml::detail::at_least<1>>;
+    skip_ws::invoke(loc);
+
+    // literal may be a bare value. try them first.
+    if(auto data = ::toml::detail::parse_value(loc))
+    {
+        return data.unwrap();
+    }
+
+    // literal is a TOML file (i.e. multiline table).
+    if(auto data = ::toml::detail::parse_toml_file(loc))
+    {
+        loc.iter() = loc.begin(); // rollback to the top of the literal
+        return ::toml::value(std::move(data.unwrap()),
+                ::toml::detail::region<std::vector<char>>(std::move(loc)));
+    }
+    else // none of them.
+    {
+        throw ::toml::syntax_error(data.unwrap_err());
+    }
+}
+
+} // toml_literals
+} // literals
+} // toml
+#endif//TOML11_LITERAL_HPP

toml/region.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_REGION_H
-#define TOML11_REGION_H
+#ifndef TOML11_REGION_HPP
+#define TOML11_REGION_HPP
 #include "exception.hpp"
 #include <memory>
 #include <vector>
@@ -15,7 +15,7 @@ namespace toml
 namespace detail
 {
 
-// helper function to avoid std::string(0, 'c')
+// helper function to avoid std::string(0, 'c') or std::string(iter, iter)
 template<typename Iterator>
 std::string make_string(Iterator first, Iterator last)
 {
@@ -28,47 +28,7 @@ inline std::string make_string(std::size_t len, char c)
     return std::string(len, c);
 }
 
-// location in a container, normally in a file content.
-// shared_ptr points the resource that the iter points.
-// it can be used not only for resource handling, but also error message.
-template<typename Container>
-struct location
-{
-    static_assert(std::is_same<char, typename Container::value_type>::value,"");
-    using const_iterator = typename Container::const_iterator;
-    using source_ptr     = std::shared_ptr<const Container>;
-
-    location(std::string name, Container cont)
-      : source_(std::make_shared<Container>(std::move(cont))),
-        source_name_(std::move(name)), iter_(source_->cbegin())
-    {}
-    location(const location&) = default;
-    location(location&&)      = default;
-    location& operator=(const location&) = default;
-    location& operator=(location&&)      = default;
-    ~location() = default;
-
-    const_iterator& iter()       noexcept {return iter_;}
-    const_iterator  iter() const noexcept {return iter_;}
-
-    const_iterator  begin() const noexcept {return source_->cbegin();}
-    const_iterator  end()   const noexcept {return source_->cend();}
-
-    source_ptr const& source() const& noexcept {return source_;}
-    source_ptr&&      source() &&     noexcept {return std::move(source_);}
-
-    std::string const& name() const noexcept {return source_name_;}
-
-  private:
-
-    source_ptr     source_;
-    std::string    source_name_;
-    const_iterator iter_;
-};
-
-// region in a container, normally in a file content.
-// shared_ptr points the resource that the iter points.
-// combinators returns this.
+// region_base is a base class of location and region that are defined below.
 // it will be used to generate better error messages.
 struct region_base
 {
@@ -86,12 +46,96 @@ struct region_base
     virtual std::string line()     const {return std::string("unknown line");}
     virtual std::string line_num() const {return std::string("?");}
 
-
-    virtual std::size_t before()   const noexcept {return 0;}
+    // length of the region
     virtual std::size_t size()     const noexcept {return 0;}
+    // number of characters in the line before the region
+    virtual std::size_t before()   const noexcept {return 0;}
+    // number of characters in the line after the region
     virtual std::size_t after()    const noexcept {return 0;}
 };
 
+// location represents a position in a container, which contains a file content.
+// it can be considered as a region that contains only one character.
+//
+// it contains pointer to the file content and iterator that points the current
+// location.
+template<typename Container>
+struct location final : public region_base
+{
+    static_assert(std::is_same<char, typename Container::value_type>::value,"");
+    using const_iterator = typename Container::const_iterator;
+    using source_ptr     = std::shared_ptr<const Container>;
+
+    location(std::string name, Container cont)
+      : source_(std::make_shared<Container>(std::move(cont))),
+        source_name_(std::move(name)), iter_(source_->cbegin())
+    {}
+    location(const location&) = default;
+    location(location&&)      = default;
+    location& operator=(const location&) = default;
+    location& operator=(location&&)      = default;
+    ~location() = default;
+
+    bool is_ok() const noexcept override {return static_cast<bool>(source_);}
+
+    const_iterator& iter()       noexcept {return iter_;}
+    const_iterator  iter() const noexcept {return iter_;}
+
+    const_iterator  begin() const noexcept {return source_->cbegin();}
+    const_iterator  end()   const noexcept {return source_->cend();}
+
+    std::string str()  const override {return make_string(1, *this->iter());}
+    std::string name() const override {return source_name_;}
+
+    std::string line_num() const override
+    {
+        return std::to_string(1+std::count(this->begin(), this->iter(), '\n'));
+    }
+
+    std::string line() const override
+    {
+        return make_string(this->line_begin(), this->line_end());
+    }
+
+    const_iterator line_begin() const noexcept
+    {
+        using reverse_iterator = std::reverse_iterator<const_iterator>;
+        return std::find(reverse_iterator(this->iter()),
+                         reverse_iterator(this->begin()), '\n').base();
+    }
+    const_iterator line_end() const noexcept
+    {
+        return std::find(this->iter(), this->end(), '\n');
+    }
+
+    // location is always points a character. so the size is 1.
+    std::size_t size() const noexcept override
+    {
+        return 1u;
+    }
+    std::size_t before() const noexcept override
+    {
+        return std::distance(this->line_begin(), this->iter());
+    }
+    std::size_t after() const noexcept override
+    {
+        return std::distance(this->iter(), this->line_end());
+    }
+
+    source_ptr const& source() const& noexcept {return source_;}
+    source_ptr&&      source() &&     noexcept {return std::move(source_);}
+
+  private:
+
+    source_ptr     source_;
+    std::string    source_name_;
+    const_iterator iter_;
+};
+
+// region represents a range in a container, which contains a file content.
+//
+// it contains pointer to the file content and iterator that points the first
+// and last location.
 template<typename Container>
 struct region final : public region_base
 {
@@ -200,96 +244,67 @@ struct region final : public region_base
 
 // to show a better error message.
 inline std::string format_underline(const std::string& message,
-        const region_base& reg, const std::string& comment_for_underline,
+        std::vector<std::pair<region_base const*, std::string>> reg_com,
         std::vector<std::string> helps = {})
 {
+    assert(!reg_com.empty());
+
 #ifdef _WIN32
     const auto newline = "\r\n";
 #else
     const char newline = '\n';
 #endif
-    const auto line        = reg.line();
-    const auto line_number = reg.line_num();
 
-    std::string retval;
-    retval += message;
-    retval += newline;
-    retval += " --> ";
-    retval += reg.name();
-    retval += newline;
-    retval += ' ';
-    retval += line_number;
-    retval += " | ";
-    retval += line;
-    retval += newline;
-    retval += make_string(line_number.size() + 1, ' ');
-    retval += " | ";
-    retval += make_string(reg.before(), ' ');
-    retval += make_string(reg.size(),   '~');
-    retval += ' ';
-    retval += comment_for_underline;
-    if(helps.size() != 0)
-    {
-        retval += newline;
-        retval += make_string(line_number.size() + 1, ' ');
-        retval += " | ";
-        for(const auto help : helps)
+    const auto line_num_width = std::max_element(reg_com.begin(), reg_com.end(),
+        [](std::pair<region_base const*, std::string> const& lhs,
+           std::pair<region_base const*, std::string> const& rhs)
         {
-            retval += newline;
-            retval += "Hint: ";
-            retval += help;
+            return lhs.first->line_num().size() < rhs.first->line_num().size();
         }
-    }
-    return retval;
-}
-
-// to show a better error message.
-inline std::string format_underline(const std::string& message,
-        const region_base& reg1, const std::string& comment_for_underline1,
-        const region_base& reg2, const std::string& comment_for_underline2,
-        std::vector<std::string> helps = {})
-{
-#ifdef _WIN32
-    const auto newline = "\r\n";
-#else
-    const char newline = '\n';
-#endif
-    const auto line1        = reg1.line();
-    const auto line_number1 = reg1.line_num();
-    const auto line2        = reg2.line();
-    const auto line_number2 = reg2.line_num();
-    const auto line_num_width =
-        std::max(line_number1.size(), line_number2.size());
+    )->first->line_num().size();
 
     std::ostringstream retval;
     retval << message << newline;
-    retval << " --> " << reg1.name() << newline;
-//  ---------------------------------------
-    retval << ' ' << std::setw(line_num_width) << line_number1;
-    retval << " | " << line1 << newline;
-    retval << make_string(line_num_width + 1, ' ');
-    retval << " | ";
-    retval << make_string(reg1.before(), ' ');
-    retval << make_string(reg1.size(),   '~');
-    retval << ' ';
-    retval << comment_for_underline1 << newline;
-//  ---------------------------------------
-    if(reg2.name() != reg1.name())
+
+    for(std::size_t i=0; i<reg_com.size(); ++i)
     {
-        retval << " --> " << reg2.name() << newline;
+        if(i!=0 && reg_com.at(i-1).first->name() == reg_com.at(i).first->name())
+        {
+            retval << newline << " ..." << newline;
+        }
+        else
+        {
+            if(i != 0) {retval << newline;}
+            retval << " --> " << reg_com.at(i).first->name() << newline;
+        }
+
+        const region_base* const reg = reg_com.at(i).first;
+        const std::string&   comment = reg_com.at(i).second;
+
+
+        retval << ' ' << std::setw(line_num_width) << reg->line_num();
+        retval << " | " << reg->line() << newline;
+        retval << make_string(line_num_width + 1, ' ');
+        retval << " | " << make_string(reg->before(), ' ');
+
+        if(reg->size() == 1)
+        {
+            // invalid
+            // ^------
+            retval << '^';
+            retval << make_string(reg->after(), '-');
+        }
+        else
+        {
+            // invalid
+            // ~~~~~~~
+            retval << make_string(reg->size(), '~');
+        }
+
+        retval << ' ';
+        retval << comment;
     }
-    else
-    {
-        retval << " ..." << newline;
-    }
-    retval << ' ' << std::setw(line_num_width) << line_number2;
-    retval << " | " << line2 << newline;
-    retval << make_string(line_num_width + 1, ' ');
-    retval << " | ";
-    retval << make_string(reg2.before(), ' ');
-    retval << make_string(reg2.size(),   '~');
-    retval << ' ';
-    retval << comment_for_underline2;
+
     if(helps.size() != 0)
     {
         retval << newline;
@@ -305,62 +320,6 @@ inline std::string format_underline(const std::string& message,
     return retval.str();
 }
 
-
-// to show a better error message.
-template<typename Container>
-std::string
-format_underline(const std::string& message, const location<Container>& loc,
-                 const std::string& comment_for_underline,
-                 std::vector<std::string> helps = {})
-{
-#ifdef _WIN32
-    const auto newline = "\r\n";
-#else
-    const char newline = '\n';
-#endif
-    using const_iterator   = typename location<Container>::const_iterator;
-    using reverse_iterator = std::reverse_iterator<const_iterator>;
-    const auto line_begin  = std::find(reverse_iterator(loc.iter()),
-                                       reverse_iterator(loc.begin()),
-                                       '\n').base();
-    const auto line_end    = std::find(loc.iter(), loc.end(), '\n');
-
-    const auto line_number = std::to_string(
-            1 + std::count(loc.begin(), loc.iter(), '\n'));
-
-    std::string retval;
-    retval += message;
-    retval += newline;
-    retval += " --> ";
-    retval += loc.name();
-    retval += newline;
-    retval += ' ';
-    retval += line_number;
-    retval += " | ";
-    retval += make_string(line_begin, line_end);
-    retval += newline;
-    retval += make_string(line_number.size() + 1, ' ');
-    retval += " | ";
-    retval += make_string(std::distance(line_begin, loc.iter()),' ');
-    retval += '^';
-    retval += make_string(std::distance(loc.iter(), line_end), '-');
-    retval += ' ';
-    retval += comment_for_underline;
-    if(helps.size() != 0)
-    {
-        retval += newline;
-        retval += make_string(line_number.size() + 1, ' ');
-        retval += " | ";
-        for(const auto help : helps)
-        {
-            retval += newline;
-            retval += "Hint: ";
-            retval += help;
-        }
-    }
-    return retval;
-}
-
 } // detail
 } // toml
 #endif// TOML11_REGION_H

toml/result.hpp

@@ -1,7 +1,8 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_RESULT_H
-#define TOML11_RESULT_H
+#ifndef TOML11_RESULT_HPP
+#define TOML11_RESULT_HPP
+#include "traits.hpp"
 #include <type_traits>
 #include <stdexcept>
 #include <utility>
@@ -13,19 +14,6 @@
 namespace toml
 {
 
-#if __cplusplus >= 201703L
-
-template<typename F, typename ... Args>
-using return_type_of_t = std::invoke_result_t<F, Args...>;
-
-#else
-// result_of is deprecated after C++17
-template<typename F, typename ... Args>
-using return_type_of_t = typename std::result_of<F(Args...)>::type;
-
-#endif
-
-
 template<typename T>
 struct success
 {
@@ -441,21 +429,21 @@ struct result
     // F: T -> U
     // retval: result<U, E>
     template<typename F>
-    result<return_type_of_t<F, value_type&>, error_type>
+    result<detail::return_type_of_t<F, value_type&>, error_type>
     map(F&& f) &
     {
         if(this->is_ok()){return ok(f(this->as_ok()));}
         return err(this->as_err());
     }
     template<typename F>
-    result<return_type_of_t<F, value_type const&>, error_type>
+    result<detail::return_type_of_t<F, value_type const&>, error_type>
     map(F&& f) const&
     {
         if(this->is_ok()){return ok(f(this->as_ok()));}
         return err(this->as_err());
     }
     template<typename F>
-    result<return_type_of_t<F, value_type &&>, error_type>
+    result<detail::return_type_of_t<F, value_type &&>, error_type>
     map(F&& f) &&
     {
         if(this->is_ok()){return ok(f(std::move(this->as_ok())));}
@@ -466,21 +454,21 @@ struct result
     // F: E -> F
     // retval: result<T, F>
     template<typename F>
-    result<value_type, return_type_of_t<F, error_type&>>
+    result<value_type, detail::return_type_of_t<F, error_type&>>
     map_err(F&& f) &
     {
         if(this->is_err()){return err(f(this->as_err()));}
         return ok(this->as_ok());
     }
     template<typename F>
-    result<value_type, return_type_of_t<F, error_type const&>>
+    result<value_type, detail::return_type_of_t<F, error_type const&>>
     map_err(F&& f) const&
     {
         if(this->is_err()){return err(f(this->as_err()));}
         return ok(this->as_ok());
     }
     template<typename F>
-    result<value_type, return_type_of_t<F, error_type&&>>
+    result<value_type, detail::return_type_of_t<F, error_type&&>>
     map_err(F&& f) &&
     {
         if(this->is_err()){return err(f(std::move(this->as_err())));}
@@ -491,21 +479,21 @@ struct result
     // F: T -> U
     // retval: U
     template<typename F, typename U>
-    return_type_of_t<F, value_type&>
+    detail::return_type_of_t<F, value_type&>
     map_or_else(F&& f, U&& opt) &
     {
         if(this->is_err()){return std::forward<U>(opt);}
         return f(this->as_ok());
     }
     template<typename F, typename U>
-    return_type_of_t<F, value_type const&>
+    detail::return_type_of_t<F, value_type const&>
     map_or_else(F&& f, U&& opt) const&
     {
         if(this->is_err()){return std::forward<U>(opt);}
         return f(this->as_ok());
     }
     template<typename F, typename U>
-    return_type_of_t<F, value_type&&>
+    detail::return_type_of_t<F, value_type&&>
     map_or_else(F&& f, U&& opt) &&
     {
         if(this->is_err()){return std::forward<U>(opt);}
@@ -516,21 +504,21 @@ struct result
     // F: E -> U
     // retval: U
     template<typename F, typename U>
-    return_type_of_t<F, error_type&>
+    detail::return_type_of_t<F, error_type&>
     map_err_or_else(F&& f, U&& opt) &
     {
         if(this->is_ok()){return std::forward<U>(opt);}
         return f(this->as_err());
     }
     template<typename F, typename U>
-    return_type_of_t<F, error_type const&>
+    detail::return_type_of_t<F, error_type const&>
     map_err_or_else(F&& f, U&& opt) const&
     {
         if(this->is_ok()){return std::forward<U>(opt);}
         return f(this->as_err());
     }
     template<typename F, typename U>
-    return_type_of_t<F, error_type&&>
+    detail::return_type_of_t<F, error_type&&>
     map_err_or_else(F&& f, U&& opt) &&
     {
         if(this->is_ok()){return std::forward<U>(opt);}
@@ -542,21 +530,21 @@ struct result
     // toml::err(error_type) should be convertible to U.
     // normally, type U is another result<S, F> and E is convertible to F
     template<typename F>
-    return_type_of_t<F, value_type&>
+    detail::return_type_of_t<F, value_type&>
     and_then(F&& f) &
     {
         if(this->is_ok()){return f(this->as_ok());}
         return err(this->as_err());
     }
     template<typename F>
-    return_type_of_t<F, value_type const&>
+    detail::return_type_of_t<F, value_type const&>
     and_then(F&& f) const&
     {
         if(this->is_ok()){return f(this->as_ok());}
         return err(this->as_err());
     }
     template<typename F>
-    return_type_of_t<F, value_type&&>
+    detail::return_type_of_t<F, value_type&&>
     and_then(F&& f) &&
     {
         if(this->is_ok()){return f(std::move(this->as_ok()));}
@@ -568,21 +556,21 @@ struct result
     // toml::ok(value_type) should be convertible to U.
     // normally, type U is another result<S, F> and T is convertible to S
     template<typename F>
-    return_type_of_t<F, error_type&>
+    detail::return_type_of_t<F, error_type&>
     or_else(F&& f) &
     {
         if(this->is_err()){return f(this->as_err());}
         return ok(this->as_ok());
     }
     template<typename F>
-    return_type_of_t<F, error_type const&>
+    detail::return_type_of_t<F, error_type const&>
     or_else(F&& f) const&
     {
         if(this->is_err()){return f(this->as_err());}
         return ok(this->as_ok());
     }
     template<typename F>
-    return_type_of_t<F, error_type&&>
+    detail::return_type_of_t<F, error_type&&>
     or_else(F&& f) &&
     {
         if(this->is_err()){return f(std::move(this->as_err()));}

toml/serializer.hpp

@@ -0,0 +1,527 @@
+//     Copyright Toru Niina 2019.
+// Distributed under the MIT License.
+#ifndef TOML11_SERIALIZER_HPP
+#define TOML11_SERIALIZER_HPP
+#include "value.hpp"
+#include "lexer.hpp"
+#include <limits>
+#include <cstdio>
+
+namespace toml
+{
+
+struct serializer
+{
+    serializer(const std::size_t w              = 80,
+               const int         float_prec     = std::numeric_limits<toml::floating>::max_digits10,
+               const bool        can_be_inlined = false,
+               std::vector<toml::key> ks        = {})
+        : can_be_inlined_(can_be_inlined), float_prec_(float_prec), width_(w),
+          keys_(std::move(ks))
+    {}
+    ~serializer() = default;
+
+    std::string operator()(const toml::boolean& b) const
+    {
+        return b ? "true" : "false";
+    }
+    std::string operator()(const integer i) const
+    {
+        return std::to_string(i);
+    }
+    std::string operator()(const toml::floating f) const
+    {
+        const auto fmt = "%.*g";
+        const auto bsz = std::snprintf(nullptr, 0, fmt, this->float_prec_, f);
+        std::vector<char> buf(bsz + 1, '\0'); // +1 for null character(\0)
+        std::snprintf(buf.data(), buf.size(), fmt, this->float_prec_, f);
+
+        std::string token(buf.begin(), std::prev(buf.end()));
+        if(token.back() == '.') // 1. => 1.0
+        {
+            token += '0';
+        }
+        const auto e = std::find_if(token.cbegin(), token.cend(),
+            [](const char c) -> bool {
+                return c == 'E' || c == 'e';
+            });
+        if(e == token.cend())
+        {
+            return token; // there is no exponent part. just return it.
+        }
+
+        // zero-prefix in an exponent is not allowed in TOML.
+        // remove it if it exists.
+        bool        sign_exists = false;
+        std::size_t zero_prefix = 0;
+        for(auto iter = std::next(e), iend = token.cend(); iter != iend; ++iter)
+        {
+            if(*iter == '+' || *iter == '-'){sign_exists = true; continue;}
+            if(*iter == '0'){zero_prefix += 1;}
+            else {break;}
+        }
+        if(zero_prefix != 0)
+        {
+            const auto offset = std::distance(token.cbegin(), e) +
+                               (sign_exists ? 2 : 1);
+            token.erase(offset, zero_prefix);
+        }
+        return token;
+    }
+    std::string operator()(const string& s) const
+    {
+        if(s.kind == string_t::basic)
+        {
+            if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend())
+            {
+                // if linefeed is contained, make it multiline-string.
+                const std::string open("\"\"\"\n");
+                const std::string close("\\\n\"\"\"");
+                return open + this->escape_ml_basic_string(s.str) + close;
+            }
+
+            // no linefeed. try to make it oneline-string.
+            std::string oneline = this->escape_basic_string(s.str);
+            if(oneline.size() + 2 < width_ || width_ < 2)
+            {
+                const std::string quote("\"");
+                return quote + oneline + quote;
+            }
+
+            // the line is too long compared to the specified width.
+            // split it into multiple lines.
+            std::string token("\"\"\"\n");
+            while(!oneline.empty())
+            {
+                if(oneline.size() < width_)
+                {
+                    token += oneline;
+                    oneline.clear();
+                }
+                else if(oneline.at(width_-2) == '\\')
+                {
+                    token += oneline.substr(0, width_-2);
+                    token += "\\\n";
+                    oneline.erase(0, width_-2);
+                }
+                else
+                {
+                    token += oneline.substr(0, width_-1);
+                    token += "\\\n";
+                    oneline.erase(0, width_-1);
+                }
+            }
+            return token + std::string("\\\n\"\"\"");
+        }
+        else // the string `s` is literal-string.
+        {
+            if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
+               std::find(s.str.cbegin(), s.str.cend(), '\'') != s.str.cend() )
+            {
+                const std::string open("'''\n");
+                const std::string close("'''");
+                return open + s.str + close;
+            }
+            else
+            {
+                const std::string quote("'");
+                return quote + s.str + quote;
+            }
+        }
+    }
+
+    std::string operator()(const local_date& d) const
+    {
+        std::ostringstream oss;
+        oss << d;
+        return oss.str();
+    }
+    std::string operator()(const local_time& t) const
+    {
+        std::ostringstream oss;
+        oss << t;
+        return oss.str();
+    }
+    std::string operator()(const local_datetime& dt) const
+    {
+        std::ostringstream oss;
+        oss << dt;
+        return oss.str();
+    }
+    std::string operator()(const offset_datetime& odt) const
+    {
+        std::ostringstream oss;
+        oss << odt;
+        return oss.str();
+    }
+
+    std::string operator()(const array& v) const
+    {
+        if(!v.empty() && v.front().is(value_t::Table))// v is an array of tables
+        {
+            // if it's not inlined, we need to add `[[table.key]]`.
+            // but if it can be inlined, we need `table.key = [...]`.
+            if(this->can_be_inlined_)
+            {
+                std::string token;
+                if(!keys_.empty())
+                {
+                    token += this->serialize_key(keys_.back());
+                    token += " = ";
+                }
+                bool width_exceeds = false;
+                token += "[\n";
+                for(const auto& item : v)
+                {
+                    const auto t =
+                        this->make_inline_table(item.cast<value_t::Table>());
+
+                    if(t.size() + 1 > width_ || // +1 for the last comma {...},
+                       std::find(t.cbegin(), t.cend(), '\n') != t.cend())
+                    {
+                        width_exceeds = true;
+                        break;
+                    }
+                    token += t;
+                    token += ",\n";
+                }
+                if(!width_exceeds)
+                {
+                    token += "]\n";
+                    return token;
+                }
+                // if width_exceeds, serialize it as [[array.of.tables]].
+            }
+
+            std::string token;
+            for(const auto& item : v)
+            {
+                token += "[[";
+                token += this->serialize_dotted_key(keys_);
+                token += "]]\n";
+                token += this->make_multiline_table(item.cast<value_t::Table>());
+            }
+            return token;
+        }
+        if(v.empty())
+        {
+            return std::string("[]");
+        }
+
+        // not an array of tables. normal array. first, try to make it inline.
+        {
+            const auto inl = this->make_inline_array(v);
+            if(inl.size() < this->width_ &&
+               std::find(inl.cbegin(), inl.cend(), '\n') == inl.cend())
+            {
+                return inl;
+            }
+        }
+
+        // if the length exceeds this->width_, print multiline array
+        std::string token;
+        std::string current_line;
+        token += "[\n";
+        for(const auto& item : v)
+        {
+            auto next_elem = toml::visit(*this, item);
+            // newline between array-value and comma is not allowed
+            if(next_elem.back() == '\n'){next_elem.pop_back();}
+
+            if(current_line.size() + next_elem.size() + 1 < this->width_)
+            {
+                current_line += next_elem;
+                current_line += ',';
+            }
+            else if(current_line.empty())
+            {
+                // the next elem cannot be within the width.
+                token += next_elem;
+                token += ",\n";
+                // keep current line empty
+            }
+            else // current_line has some tokens and it exceeds width
+            {
+                assert(current_line.back() == ',');
+                token += current_line;
+                token += '\n';
+                current_line = next_elem;
+                current_line += ',';
+            }
+        }
+        if(!current_line.empty())
+        {
+            if(current_line.back() != '\n') {current_line += '\n';}
+            token += current_line;
+        }
+        token += "]\n";
+        return token;
+    }
+
+    std::string operator()(const table& v) const
+    {
+        if(this->can_be_inlined_)
+        {
+            std::string token;
+            if(!this->keys_.empty())
+            {
+                token += this->serialize_key(this->keys_.back());
+                token += " = ";
+            }
+            token += this->make_inline_table(v);
+            if(token.size() < this->width_)
+            {
+                return token;
+            }
+        }
+
+        std::string token;
+        if(!keys_.empty())
+        {
+            token += '[';
+            token += this->serialize_dotted_key(keys_);
+            token += "]\n";
+        }
+        token += this->make_multiline_table(v);
+        return token;
+    }
+
+  private:
+
+    std::string serialize_key(const toml::key& key) const
+    {
+        detail::location<toml::key> loc(key, key);
+        detail::lex_unquoted_key::invoke(loc);
+        if(loc.iter() == loc.end())
+        {
+            return key; // all the tokens are consumed. the key is unquoted-key.
+        }
+        std::string token("\"");
+        token += this->escape_basic_string(key);
+        token += "\"";
+        return token;
+    }
+
+    std::string serialize_dotted_key(const std::vector<toml::key>& keys) const
+    {
+        std::string token;
+        if(keys.empty()){return token;}
+
+        for(const auto& k : keys)
+        {
+            token += this->serialize_key(k);
+            token += '.';
+        }
+        token.erase(token.size() - 1, 1); // remove trailing `.`
+        return token;
+    }
+
+    std::string escape_basic_string(const std::string& s) const
+    {
+        //XXX assuming `s` is a valid utf-8 sequence.
+        std::string retval;
+        for(const char c : s)
+        {
+            switch(c)
+            {
+                case '\\': {retval += "\\\\"; break;}
+                case '\"': {retval += "\\\""; break;}
+                case '\b': {retval += "\\b";  break;}
+                case '\t': {retval += "\\t";  break;}
+                case '\f': {retval += "\\f";  break;}
+                case '\n': {retval += "\\n";  break;}
+                case '\r': {retval += "\\r";  break;}
+                default  : {retval += c;      break;}
+            }
+        }
+        return retval;
+    }
+
+    std::string escape_ml_basic_string(const std::string& s) const
+    {
+        std::string retval;
+        for(auto i=s.cbegin(), e=s.cend(); i!=e; ++i)
+        {
+            switch(*i)
+            {
+                case '\\': {retval += "\\\\"; break;}
+                case '\"': {retval += "\\\""; break;}
+                case '\b': {retval += "\\b";  break;}
+                case '\t': {retval += "\\t";  break;}
+                case '\f': {retval += "\\f";  break;}
+                case '\n': {retval += "\n";   break;}
+                case '\r':
+                {
+                    if(std::next(i) != e && *std::next(i) == '\n')
+                    {
+                        retval += "\r\n";
+                        ++i;
+                    }
+                    else
+                    {
+                        retval += "\\r";
+                    }
+                    break;
+                }
+                default: {retval += *i; break;}
+            }
+        }
+        return retval;
+    }
+
+    std::string make_inline_array(const array& v) const
+    {
+        std::string token;
+        token += '[';
+        bool is_first = true;
+        for(const auto& item : v)
+        {
+            if(is_first) {is_first = false;} else {token += ',';}
+            token += visit(serializer(std::numeric_limits<std::size_t>::max(),
+                                      this->float_prec_, true), item);
+        }
+        token += ']';
+        return token;
+    }
+
+    std::string make_inline_table(const table& v) const
+    {
+        assert(this->can_be_inlined_);
+        std::string token;
+        token += '{';
+        bool is_first = true;
+        for(const auto& kv : v)
+        {
+            // in inline tables, trailing comma is not allowed (toml-lang #569).
+            if(is_first) {is_first = false;} else {token += ',';}
+            token += this->serialize_key(kv.first);
+            token += '=';
+            token += visit(serializer(std::numeric_limits<std::size_t>::max(),
+                                      this->float_prec_, true), kv.second);
+        }
+        token += '}';
+        return token;
+    }
+
+    std::string make_multiline_table(const table& v) const
+    {
+        std::string token;
+
+        // print non-table stuff first. because after printing [foo.bar], the
+        // remaining non-table values will be assigned into [foo.bar], not [foo]
+        for(const auto kv : v)
+        {
+            if(kv.second.is(value_t::Table) || is_array_of_tables(kv.second))
+            {
+                continue;
+            }
+
+            const auto key_and_sep    = this->serialize_key(kv.first) + " = ";
+            const auto residual_width = (this->width_ > key_and_sep.size()) ?
+                                        this->width_ - key_and_sep.size() : 0;
+            token += key_and_sep;
+            token += visit(serializer(residual_width, this->float_prec_, true),
+                           kv.second);
+            if(token.back() != '\n')
+            {
+                token += '\n';
+            }
+        }
+
+        // normal tables / array of tables
+
+        // after multiline table appeared, the other tables cannot be inline
+        // because the table would be assigned into the table.
+        // [foo]
+        // ...
+        // bar = {...} # <- bar will be a member of [foo].
+        bool multiline_table_printed = false;
+        for(const auto& kv : v)
+        {
+            if(!kv.second.is(value_t::Table) && !is_array_of_tables(kv.second))
+            {
+                continue; // other stuff are already serialized. skip them.
+            }
+
+            std::vector<toml::key> ks(this->keys_);
+            ks.push_back(kv.first);
+
+            auto tmp = visit(serializer(
+                this->width_, this->float_prec_, !multiline_table_printed, ks),
+                kv.second);
+
+            if((!multiline_table_printed) &&
+               std::find(tmp.cbegin(), tmp.cend(), '\n') != tmp.cend())
+            {
+                multiline_table_printed = true;
+            }
+            else
+            {
+                // still inline tables only.
+                tmp += '\n';
+            }
+            token += tmp;
+        }
+        return token;
+    }
+
+    bool is_array_of_tables(const value& v) const
+    {
+        if(!v.is(value_t::Array)) {return false;}
+
+        const auto& a = v.cast<value_t::Array>();
+        return !a.empty() && a.front().is(value_t::Table);
+    }
+
+  private:
+
+    bool        can_be_inlined_;
+    int         float_prec_;
+    std::size_t width_;
+    std::vector<toml::key> keys_;
+};
+
+inline std::string
+format(const value& v, std::size_t w = 80,
+       int fprec = std::numeric_limits<toml::floating>::max_digits10,
+       bool force_inline = false)
+{
+    // if value is a table, it is considered to be a root object.
+    // the root object can't be an inline table. so pass false. otherwise, true.
+    return visit(serializer(w, fprec, (!v.is_table()) || force_inline), v);
+}
+inline std::string
+format(const table& t, std::size_t w = 80,
+       int fprec = std::numeric_limits<toml::floating>::max_digits10,
+       bool force_inline = false)
+{
+    return serializer(w, fprec, force_inline)(t);
+}
+
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const value& v)
+{
+    // get status of std::setw().
+    const std::size_t w     = os.width();
+    const int         fprec = os.precision();
+    os.width(0);
+    // the root object can't be an inline table. so pass `false`.
+    os << visit(serializer(w, fprec, false), v);
+    return os;
+}
+template<typename charT, typename traits>
+std::basic_ostream<charT, traits>&
+operator<<(std::basic_ostream<charT, traits>& os, const table& v)
+{
+    // get status of std::setw().
+    const std::size_t w     = os.width();
+    const int         fprec = os.precision();
+    os.width(0);
+    // the root object can't be an inline table. so pass `false`.
+    os << serializer(w, fprec, false)(v);
+    return os;
+}
+
+} // toml
+#endif// TOML11_SERIALIZER_HPP

toml/string.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_STRING_H
-#define TOML11_STRING_H
+#ifndef TOML11_STRING_HPP
+#define TOML11_STRING_HPP
 #include <string>
 #include <cstdint>
 

toml/to_toml.hpp

@@ -1,43 +0,0 @@
-//     Copyright Toru Niina 2017.
-// Distributed under the MIT License.
-#ifndef TOML11_TO_TOML
-#define TOML11_TO_TOML
-#include "value.hpp"
-
-namespace toml
-{
-
-template<typename T>
-inline value to_toml(T&& x)
-{
-    return value(std::forward<T>(x));
-}
-
-template<typename T>
-inline value to_toml(T&& x, string_t kind)
-{
-    return value(std::forward<T>(x), kind);
-}
-
-inline value to_toml(local_date d, local_time t)
-{
-    return value(local_datetime(d, t));
-}
-inline value to_toml(local_date d, local_time t, time_offset ofs)
-{
-    return value(offset_datetime(d, t, ofs));
-}
-
-template<typename ... Ts>
-inline value to_toml(Ts&& ... xs)
-{
-    return value(toml::array{toml::value(std::forward<Ts>(xs)) ... });
-}
-
-inline value to_toml(std::initializer_list<std::pair<std::string, toml::value>> xs)
-{
-    return value(toml::table(xs.begin(), xs.end()));
-}
-
-} // toml
-#endif // TOML11_TO_TOML

toml/traits.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_TRAITS
-#define TOML11_TRAITS
+#ifndef TOML11_TRAITS_HPP
+#define TOML11_TRAITS_HPP
 #include <type_traits>
 #include <utility>
 #include <chrono>
@@ -9,12 +9,18 @@
 
 namespace toml
 {
+
+class value; // forward decl
+
 namespace detail
 {
 
 template<typename T>
 using unwrap_t = typename std::decay<T>::type;
 
+// ---------------------------------------------------------------------------
+// check whether type T is a kind of container/map class
+
 struct has_iterator_impl
 {
     template<typename T> static std::true_type  check(typename T::iterator*);
@@ -42,6 +48,22 @@ struct has_resize_method_impl
     template<typename T> static std::false_type check(...);
 };
 
+struct has_from_toml_method_impl
+{
+    template<typename T>
+    static std::true_type  check(
+        decltype(std::declval<T>().from_toml(std::declval<::toml::value>()))*);
+    template<typename T>
+    static std::false_type check(...);
+};
+struct has_into_toml_method_impl
+{
+    template<typename T>
+    static std::true_type  check(decltype(std::declval<T>().into_toml())*);
+    template<typename T>
+    static std::false_type check(...);
+};
+
 /// Intel C++ compiler can not use decltype in parent class declaration, here
 /// is a hack to work around it. https://stackoverflow.com/a/23953090/4692076
 #ifdef __INTEL_COMPILER
@@ -59,10 +81,21 @@ struct has_mapped_type : decltype(has_mapped_type_impl::check<T>(nullptr)){};
 template<typename T>
 struct has_resize_method : decltype(has_resize_method_impl::check<T>(nullptr)){};
 
+
+template<typename T>
+struct has_from_toml_method
+: decltype(has_from_toml_method_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_into_toml_method
+: decltype(has_into_toml_method_impl::check<T>(nullptr)){};
+
 #ifdef __INTEL_COMPILER
 #undef decltype(...)
 #endif
 
+// ---------------------------------------------------------------------------
+// C++17 and/or/not
+
 template<typename ...> struct conjunction : std::true_type{};
 template<typename T>   struct conjunction<T> : T{};
 template<typename T, typename ... Ts>
@@ -80,6 +113,9 @@ struct disjunction<T, Ts...> :
 template<typename T>
 struct negation : std::integral_constant<bool, !static_cast<bool>(T::value)>{};
 
+// ---------------------------------------------------------------------------
+// normal type checker
+
 template<typename T> struct is_std_pair : std::false_type{};
 template<typename T1, typename T2>
 struct is_std_pair<std::pair<T1, T2>> : std::true_type{};
@@ -92,7 +128,9 @@ template<typename T> struct is_chrono_duration: std::false_type{};
 template<typename Rep, typename Period>
 struct is_chrono_duration<std::chrono::duration<Rep, Period>>: std::true_type{};
 
-// to use toml::get<std::tuple<T1, T2, ...>> in C++11
+// ---------------------------------------------------------------------------
+// C++14 index_sequence
+
 template<std::size_t ... Ns> struct index_sequence{};
 
 template<typename IS, std::size_t N> struct push_back_index_sequence{};
@@ -116,6 +154,36 @@ struct index_sequence_maker<0>
 template<std::size_t N>
 using make_index_sequence = typename index_sequence_maker<N-1>::type;
 
+// ---------------------------------------------------------------------------
+// return_type_of_t
+
+#if __cplusplus >= 201703L
+
+template<typename F, typename ... Args>
+using return_type_of_t = std::invoke_result_t<F, Args...>;
+
+#else
+// result_of is deprecated after C++17
+template<typename F, typename ... Args>
+using return_type_of_t = typename std::result_of<F(Args...)>::type;
+
+#endif
+
+// ---------------------------------------------------------------------------
+// is_string_literal
+//
+// to use this, pass `typename remove_reference<T>::type` to T.
+
+template<typename T>
+struct is_string_literal:
+disjunction<
+    std::is_same<const char*, T>,
+    conjunction<
+        std::is_array<T>,
+        std::is_same<const char, typename std::remove_extent<T>::type>
+        >
+    >{};
+
 }// detail
 }//toml
 #endif // TOML_TRAITS

toml/types.hpp

@@ -1,7 +1,7 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_TYPES_H
-#define TOML11_TYPES_H
+#ifndef TOML11_TYPES_HPP
+#define TOML11_TYPES_HPP
 #include "datetime.hpp"
 #include "string.hpp"
 #include "traits.hpp"
@@ -137,17 +137,6 @@ template<> struct toml_value_t<LocalDate     >{static constexpr value_t value =
 template<> struct toml_value_t<LocalTime     >{static constexpr value_t value = value_t::LocalTime     ;};
 template<> struct toml_value_t<Array         >{static constexpr value_t value = value_t::Array         ;};
 template<> struct toml_value_t<Table         >{static constexpr value_t value = value_t::Table         ;};
-template<typename T> constexpr value_t toml_value_t<T>::value;
-constexpr value_t toml_value_t<Boolean       >::value;
-constexpr value_t toml_value_t<Integer       >::value;
-constexpr value_t toml_value_t<Float         >::value;
-constexpr value_t toml_value_t<String        >::value;
-constexpr value_t toml_value_t<OffsetDatetime>::value;
-constexpr value_t toml_value_t<LocalDatetime >::value;
-constexpr value_t toml_value_t<LocalDate     >::value;
-constexpr value_t toml_value_t<LocalTime     >::value;
-constexpr value_t toml_value_t<Array         >::value;
-constexpr value_t toml_value_t<Table         >::value;
 
 template<typename T>
 struct is_exact_toml_type : disjunction<

toml/utility.hpp

@@ -1,12 +1,22 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_UTILITY
-#define TOML11_UTILITY
+#ifndef TOML11_UTILITY_HPP
+#define TOML11_UTILITY_HPP
 #include "traits.hpp"
 #include <utility>
 #include <memory>
 #include <sstream>
 
+#if __cplusplus >= 201402L
+#  define TOML11_MARK_AS_DEPRECATED(msg) [[deprecated(msg)]]
+#elif defined(__GNUC__)
+#  define TOML11_MARK_AS_DEPRECATED(msg) __attribute__((deprecated(msg)))
+#elif defined(_MSC_VER)
+#  define TOML11_MARK_AS_DEPRECATED(msg) __declspec(deprecated(msg))
+#else
+#  define TOML11_MARK_AS_DEPRECATED
+#endif
+
 namespace toml
 {
 
@@ -29,8 +39,9 @@ inline void resize_impl(T& container, std::size_t N, std::true_type)
 template<typename T>
 inline void resize_impl(T& container, std::size_t N, std::false_type)
 {
-    if(container.size() >= N) return;
-    else throw std::invalid_argument("not resizable type");
+    if(container.size() >= N) {return;}
+
+    throw std::invalid_argument("not resizable type");
 }
 
 } // detail
@@ -38,8 +49,9 @@ inline void resize_impl(T& container, std::size_t N, std::false_type)
 template<typename T>
 inline void resize(T& container, std::size_t N)
 {
-    if(container.size() == N) return;
-    else return detail::resize_impl(container, N, detail::has_resize_method<T>());
+    if(container.size() == N) {return;}
+
+    return detail::resize_impl(container, N, detail::has_resize_method<T>());
 }
 
 namespace detail
@@ -73,7 +85,5 @@ T from_string(const std::string& str, U&& opt)
     return v;
 }
 
-
-
 }// toml
 #endif // TOML11_UTILITY

toml/value.hpp

@@ -1,8 +1,9 @@
 //     Copyright Toru Niina 2017.
 // Distributed under the MIT License.
-#ifndef TOML11_VALUE
-#define TOML11_VALUE
+#ifndef TOML11_VALUE_HPP
+#define TOML11_VALUE_HPP
 #include "traits.hpp"
+#include "into.hpp"
 #include "utility.hpp"
 #include "exception.hpp"
 #include "storage.hpp"
@@ -21,8 +22,8 @@ namespace detail
 {
 // to show error messages. not recommended for users.
 region_base const& get_region(const value&);
-// ditto.
-void assign_keeping_region(value&, value);
+template<typename Region>
+void change_region(value&, Region&&);
 }// detail
 
 template<typename T>
@@ -473,7 +474,7 @@ class value
           region_info_(std::make_shared<region_base>(region_base{}))
     {
         array ary; ary.reserve(list.size());
-        for(auto& elem : list) {ary.emplace_back(std::move(elem));}
+        for(const auto& elem : list) {ary.emplace_back(elem);}
         assigner(this->array_, std::move(ary));
     }
     template<typename T, typename std::enable_if<detail::is_container<T>::value,
@@ -485,7 +486,7 @@ class value
         this->region_info_ = std::make_shared<region_base>(region_base{});
 
         array ary; ary.reserve(list.size());
-        for(auto& elem : list) {ary.emplace_back(std::move(elem));}
+        for(const auto& elem : list) {ary.emplace_back(elem);}
         assigner(this->array_, std::move(ary));
         return *this;
     }
@@ -533,10 +534,62 @@ class value
         return *this;
     }
 
+    // user-defined =========================================================
+
+    // convert using into_toml() method -------------------------------------
+
+    template<typename T, typename std::enable_if<detail::conjunction<
+        detail::negation<detail::is_exact_toml_type<T>>, // not a toml::value
+        detail::has_into_toml_method<T> // but has `into_toml` method
+        >::value, std::nullptr_t>::type = nullptr>
+    value(const T& ud): value(ud.into_toml()) {}
+
+    template<typename T, typename std::enable_if<detail::conjunction<
+        detail::negation<detail::is_exact_toml_type<T>>, // not a toml::value
+        detail::has_into_toml_method<T> // but has `into_toml` method
+        >::value, std::nullptr_t>::type = nullptr>
+    value& operator=(const T& ud)
+    {
+        *this = ud.into_toml();
+        return *this;
+    }
+
+    // convert using into<T> struct -----------------------------------------
+
+    template<typename T, typename std::enable_if<
+        detail::negation<detail::is_exact_toml_type<T>>::value,
+        std::nullptr_t>::type = nullptr,
+        std::size_t S = sizeof(::toml::into<T>)>
+    value(const T& ud): value(::toml::into<T>::into_toml(ud)) {}
+
+    template<typename T, typename std::enable_if<
+        detail::negation<detail::is_exact_toml_type<T>>::value,
+        std::nullptr_t>::type = nullptr,
+        std::size_t S = sizeof(::toml::into<T>)>
+    value& operator=(const T& ud)
+    {
+        *this = ::toml::into<T>::into_toml(ud);
+        return *this;
+    }
+
+    // type checking and casting ============================================
+
     template<typename T>
     bool is() const noexcept {return value_traits<T>::type_index == this->type_;}
     bool is(value_t t) const noexcept {return t == this->type_;}
 
+    bool is_uninitialized()   const noexcept {return this->is(value_t::Empty         );}
+    bool is_boolean()         const noexcept {return this->is(value_t::Boolean       );}
+    bool is_integer()         const noexcept {return this->is(value_t::Integer       );}
+    bool is_float()           const noexcept {return this->is(value_t::Float         );}
+    bool is_string()          const noexcept {return this->is(value_t::String        );}
+    bool is_offset_datetime() const noexcept {return this->is(value_t::OffsetDatetime);}
+    bool is_local_datetime()  const noexcept {return this->is(value_t::LocalDatetime );}
+    bool is_local_date()      const noexcept {return this->is(value_t::LocalDate     );}
+    bool is_local_time()      const noexcept {return this->is(value_t::LocalTime     );}
+    bool is_array()           const noexcept {return this->is(value_t::Array         );}
+    bool is_table()           const noexcept {return this->is(value_t::Table         );}
+
     value_t type() const {return type_;}
 
     template<value_t T>
@@ -562,8 +615,8 @@ class value
     // for error messages
     friend region_base const& detail::get_region(const value&);
 
-    // to see why it's here, see detail::insert_nested_key.
-    friend void detail::assign_keeping_region(value&, value);
+    template<typename Region>
+    friend void detail::change_region(value&, Region&&);
 
     template<value_t T>
     struct switch_cast;
@@ -599,35 +652,21 @@ inline region_base const& get_region(const value& v)
 {
     return *(v.region_info_);
 }
-// If we keep region information after assigning another toml::* types, the
-// error message become different from the actual value contained.
-// To avoid this kind of confusing phenomena, the default assigners clear the
-// old region_info_. But this functionality is actually needed deep inside of
-// parser, so if you want to see the usecase, see toml::detail::insert_nested_key
-// defined in toml/parser.hpp.
-inline void assign_keeping_region(value& v, value other)
+
+template<typename Region>
+void change_region(value& v, Region&& reg)
 {
-    v.cleanup(); // this keeps region info
-    // keep region_info_ intact
-    v.type_ = other.type();
-    switch(v.type())
-    {
-        case value_t::Boolean       : ::toml::value::assigner(v.boolean_        , other.boolean_        ); break;
-        case value_t::Integer       : ::toml::value::assigner(v.integer_        , other.integer_        ); break;
-        case value_t::Float         : ::toml::value::assigner(v.floating_       , other.floating_       ); break;
-        case value_t::String        : ::toml::value::assigner(v.string_         , other.string_         ); break;
-        case value_t::OffsetDatetime: ::toml::value::assigner(v.offset_datetime_, other.offset_datetime_); break;
-        case value_t::LocalDatetime : ::toml::value::assigner(v.local_datetime_ , other.local_datetime_ ); break;
-        case value_t::LocalDate     : ::toml::value::assigner(v.local_date_     , other.local_date_     ); break;
-        case value_t::LocalTime     : ::toml::value::assigner(v.local_time_     , other.local_time_     ); break;
-        case value_t::Array         : ::toml::value::assigner(v.array_          , other.array_          ); break;
-        case value_t::Table         : ::toml::value::assigner(v.table_          , other.table_          ); break;
-        default: break;
-    }
+    using region_type = typename std::remove_reference<
+        typename std::remove_cv<Region>::type
+        >::type;
+
+    std::shared_ptr<region_base> new_reg =
+        std::make_shared<region_type>(std::forward<region_type>(reg));
+    v.region_info_ = new_reg;
     return;
 }
-}// detail
 
+}// detail
 
 template<> struct value::switch_cast<value_t::Boolean>
 {
@@ -695,9 +734,11 @@ typename detail::toml_default_type<T>::type& value::cast() &
 {
     if(T != this->type_)
     {
-        throw type_error(format_underline(concat_to_string(
-            "[error] toml::value bad_cast to ", T), *region_info_,
-            concat_to_string("the actual type is ", this->type_)));
+        throw type_error(detail::format_underline(concat_to_string(
+            "[error] toml::value bad_cast to ", T), {
+                {this->region_info_.get(),
+                 concat_to_string("the actual type is ", this->type_)}
+            }));
     }
     return switch_cast<T>::invoke(*this);
 }
@@ -706,9 +747,11 @@ typename detail::toml_default_type<T>::type const& value::cast() const&
 {
     if(T != this->type_)
     {
-        throw type_error(format_underline(concat_to_string(
-            "[error] toml::value bad_cast to ", T), *region_info_,
-            concat_to_string("the actual type is ", this->type_)));
+        throw type_error(detail::format_underline(concat_to_string(
+            "[error] toml::value bad_cast to ", T), {
+                {this->region_info_.get(),
+                 concat_to_string("the actual type is ", this->type_)}
+            }));
     }
     return switch_cast<T>::invoke(*this);
 }
@@ -717,9 +760,11 @@ typename detail::toml_default_type<T>::type&&      value::cast() &&
 {
     if(T != this->type_)
     {
-        throw type_error(format_underline(concat_to_string(
-            "[error] toml::value bad_cast to ", T), *region_info_,
-            concat_to_string("the actual type is ", this->type_)));
+        throw type_error(detail::format_underline(concat_to_string(
+            "[error] toml::value bad_cast to ", T), {
+                {this->region_info_.get(),
+                 concat_to_string("the actual type is ", this->type_)}
+             }));
     }
     return switch_cast<T>::invoke(std::move(*this));
 }
@@ -767,6 +812,8 @@ inline bool operator<(const toml::value& lhs, const toml::value& rhs)
             return lhs.cast<value_t::Float   >() < rhs.cast<value_t::Float   >();
         case value_t::String  :
             return lhs.cast<value_t::String  >() < rhs.cast<value_t::String  >();
+        case value_t::OffsetDatetime:
+            return lhs.cast<value_t::OffsetDatetime>() < rhs.cast<value_t::OffsetDatetime>();
         case value_t::LocalDatetime:
             return lhs.cast<value_t::LocalDatetime>() < rhs.cast<value_t::LocalDatetime>();
         case value_t::LocalDate:
@@ -801,17 +848,111 @@ inline bool operator>=(const toml::value& lhs, const toml::value& rhs)
 }
 
 inline std::string format_error(const std::string& err_msg,
-        const toml::value& v, const std::string& comment)
+        const toml::value& v, const std::string& comment,
+        std::vector<std::string> hints = {})
 {
-    return detail::format_underline(err_msg, detail::get_region(v), comment);
+    return detail::format_underline(err_msg,
+        std::vector<std::pair<detail::region_base const*, std::string>>{
+            {std::addressof(detail::get_region(v)), comment}
+        }, std::move(hints));
 }
 
 inline std::string format_error(const std::string& err_msg,
         const toml::value& v1, const std::string& comment1,
-        const toml::value& v2, const std::string& comment2)
+        const toml::value& v2, const std::string& comment2,
+        std::vector<std::string> hints = {})
 {
-    return detail::format_underline(err_msg, detail::get_region(v1), comment1,
-                                             detail::get_region(v2), comment2);
+    return detail::format_underline(err_msg,
+        std::vector<std::pair<detail::region_base const*, std::string>>{
+            {std::addressof(detail::get_region(v1)), comment1},
+            {std::addressof(detail::get_region(v2)), comment2}
+        }, std::move(hints));
+}
+
+inline std::string format_error(const std::string& err_msg,
+        const toml::value& v1, const std::string& comment1,
+        const toml::value& v2, const std::string& comment2,
+        const toml::value& v3, const std::string& comment3,
+        std::vector<std::string> hints = {})
+{
+    return detail::format_underline(err_msg,
+        std::vector<std::pair<detail::region_base const*, std::string>>{
+            {std::addressof(detail::get_region(v1)), comment1},
+            {std::addressof(detail::get_region(v2)), comment2},
+            {std::addressof(detail::get_region(v3)), comment3}
+        }, std::move(hints));
+}
+
+template<typename Visitor>
+detail::return_type_of_t<Visitor, const toml::boolean&>
+visit(Visitor&& visitor, const toml::value& v)
+{
+    switch(v.type())
+    {
+        case value_t::Boolean       : {return visitor(v.cast<value_t::Boolean       >());}
+        case value_t::Integer       : {return visitor(v.cast<value_t::Integer       >());}
+        case value_t::Float         : {return visitor(v.cast<value_t::Float         >());}
+        case value_t::String        : {return visitor(v.cast<value_t::String        >());}
+        case value_t::OffsetDatetime: {return visitor(v.cast<value_t::OffsetDatetime>());}
+        case value_t::LocalDatetime : {return visitor(v.cast<value_t::LocalDatetime >());}
+        case value_t::LocalDate     : {return visitor(v.cast<value_t::LocalDate     >());}
+        case value_t::LocalTime     : {return visitor(v.cast<value_t::LocalTime     >());}
+        case value_t::Array         : {return visitor(v.cast<value_t::Array         >());}
+        case value_t::Table         : {return visitor(v.cast<value_t::Table         >());}
+        case value_t::Empty         : break;
+        case value_t::Unknown       : break;
+        default: break;
+    }
+    throw std::runtime_error(format_error("[error] toml::visit: toml::value "
+            "does not have any valid value.", v, "here"));
+}
+
+template<typename Visitor>
+detail::return_type_of_t<Visitor, toml::boolean&>
+visit(Visitor&& visitor, toml::value& v)
+{
+    switch(v.type())
+    {
+        case value_t::Boolean       : {return visitor(v.cast<value_t::Boolean       >());}
+        case value_t::Integer       : {return visitor(v.cast<value_t::Integer       >());}
+        case value_t::Float         : {return visitor(v.cast<value_t::Float         >());}
+        case value_t::String        : {return visitor(v.cast<value_t::String        >());}
+        case value_t::OffsetDatetime: {return visitor(v.cast<value_t::OffsetDatetime>());}
+        case value_t::LocalDatetime : {return visitor(v.cast<value_t::LocalDatetime >());}
+        case value_t::LocalDate     : {return visitor(v.cast<value_t::LocalDate     >());}
+        case value_t::LocalTime     : {return visitor(v.cast<value_t::LocalTime     >());}
+        case value_t::Array         : {return visitor(v.cast<value_t::Array         >());}
+        case value_t::Table         : {return visitor(v.cast<value_t::Table         >());}
+        case value_t::Empty         : break;
+        case value_t::Unknown       : break;
+        default: break;
+    }
+    throw std::runtime_error(format_error("[error] toml::visit: toml::value "
+            "does not have any valid value.", v, "here"));
+}
+
+template<typename Visitor>
+detail::return_type_of_t<Visitor, toml::boolean&&>
+visit(Visitor&& visitor, toml::value&& v)
+{
+    switch(v.type())
+    {
+        case value_t::Boolean       : {return visitor(std::move(v.cast<value_t::Boolean       >()));}
+        case value_t::Integer       : {return visitor(std::move(v.cast<value_t::Integer       >()));}
+        case value_t::Float         : {return visitor(std::move(v.cast<value_t::Float         >()));}
+        case value_t::String        : {return visitor(std::move(v.cast<value_t::String        >()));}
+        case value_t::OffsetDatetime: {return visitor(std::move(v.cast<value_t::OffsetDatetime>()));}
+        case value_t::LocalDatetime : {return visitor(std::move(v.cast<value_t::LocalDatetime >()));}
+        case value_t::LocalDate     : {return visitor(std::move(v.cast<value_t::LocalDate     >()));}
+        case value_t::LocalTime     : {return visitor(std::move(v.cast<value_t::LocalTime     >()));}
+        case value_t::Array         : {return visitor(std::move(v.cast<value_t::Array         >()));}
+        case value_t::Table         : {return visitor(std::move(v.cast<value_t::Table         >()));}
+        case value_t::Empty         : break;
+        case value_t::Unknown       : break;
+        default: break;
+    }
+    throw std::runtime_error(format_error("[error] toml::visit: toml::value "
+            "does not have any valid value.", v, "here"));
 }
 
 }// toml