feat: avoid double checking in helper methods

The top-level table has its region at the first character of the file.
That means that, in the case when a key is not found in the top-level
table, the error message points to the first character. If the file has
its first table at the first line, the error message would be like this.
```console
[error] key "a" not found
 --> example.toml
   |
 1 | [table]
   | ^------ in this table
```
It actually points to the top-level table at the first character,
not `[table]`. But it is too confusing. To avoid the confusion, the
error message should explicitly say "key not found in the top-level
table".

.travis.yml

@@ -5,7 +5,31 @@ matrix:
   - os: linux
     language: cpp
     compiler: gcc
-    env: COMPILER="g++-5" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="g++-4.8" CXX_STANDARD=11
+    addons:
+      apt:
+        sources:
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+        - sourceline: 'ppa:mhier/libboost-latest'
+        packages:
+        - g++-4.8
+        - boost1.70
+  - os: linux
+    language: cpp
+    compiler: gcc
+    env: COMPILER="g++-4.9" CXX_STANDARD=11
+    addons:
+      apt:
+        sources:
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+        - sourceline: 'ppa:mhier/libboost-latest'
+        packages:
+        - g++-4.9
+        - boost1.70
+  - os: linux
+    language: cpp
+    compiler: gcc
+    env: COMPILER="g++-5" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -17,7 +41,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: gcc
-    env: COMPILER="g++-6" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="g++-6" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -29,7 +53,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: gcc
-    env: COMPILER="g++-7" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="g++-7" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -41,7 +65,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: gcc
-    env: COMPILER="g++-8" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="g++-8" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -65,7 +89,19 @@ matrix:
   - os: linux
     language: cpp
     compiler: gcc
-    env: COMPILER="g++-8" CXX_STANDARD=17 TOML_HEAD=OFF
+    env: COMPILER="g++-8" CXX_STANDARD=14
+    addons:
+      apt:
+        sources:
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+        - sourceline: 'ppa:mhier/libboost-latest'
+        packages:
+        - g++-8
+        - boost1.70
+  - os: linux
+    language: cpp
+    compiler: gcc
+    env: COMPILER="g++-8" CXX_STANDARD=17
     addons:
       apt:
         sources:
@@ -89,7 +125,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-3.9" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="clang++-3.9" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -103,7 +139,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-4.0" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="clang++-4.0" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -117,7 +153,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-5.0" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="clang++-5.0" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -131,7 +167,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-6.0" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="clang++-6.0" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -145,7 +181,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-7" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="clang++-7" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -159,7 +195,7 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-8" CXX_STANDARD=11 TOML_HEAD=OFF
+    env: COMPILER="clang++-8" CXX_STANDARD=11
     addons:
       apt:
         sources:
@@ -187,7 +223,21 @@ matrix:
   - os: linux
     language: cpp
     compiler: clang
-    env: COMPILER="clang++-8" CXX_STANDARD=17 TOML_HEAD=OFF
+    env: COMPILER="clang++-8" CXX_STANDARD=14
+    addons:
+      apt:
+        sources:
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+        - sourceline: 'ppa:mhier/libboost-latest'
+        - llvm-toolchain-trusty-8
+        packages:
+        - clang-8
+        - g++-8
+        - boost1.70
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-8" CXX_STANDARD=17
     addons:
       apt:
         sources:
@@ -212,19 +262,37 @@ matrix:
         - clang-8
         - g++-8
         - boost1.70
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-8" CXX_STANDARD=11 WITH_ASAN=ON
+    addons:
+      apt:
+        sources:
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+        - sourceline: 'ppa:mhier/libboost-latest'
+        - llvm-toolchain-trusty-8
+        packages:
+        - clang-8
+        - g++-8
+        - boost1.70
+  - os: linux
+    language: cpp
+    compiler: clang
+    env: COMPILER="clang++-8" CXX_STANDARD=11 WITH_UBSAN=ON
+    addons:
+      apt:
+        sources:
+        - sourceline: 'ppa:ubuntu-toolchain-r/test'
+        - sourceline: 'ppa:mhier/libboost-latest'
+        - llvm-toolchain-trusty-8
+        packages:
+        - clang-8
+        - g++-8
+        - boost1.70
   - os: osx
     language: cpp
     compiler: clang
-    env: CXX_STANDARD=11
-    cache:
-      directories:
-        - $HOME/Library/Caches/Homebrew
-    addons:
-      homebrew:
-        update: true
-        packages:
-        - cmake
-        - boost
 
 script:
 - |
@@ -234,17 +302,30 @@ script:
     tar xf cmake-3.14.5-Linux-x86_64.tar.gz -C cmake --strip-components=1
     export PATH=${TRAVIS_BUILD_DIR}/cmake/bin:${PATH}
   fi
+- |
+  if [[ "${CXX_STANDARD}" == "" ]]; then
+      export CXX_STANDARD="11"
+  fi
+- |
+  if [[ "${TOML_HEAD}" != "ON" ]]; then
+    export TOML_HEAD="OFF"
+  fi
+- echo "TOML_HEAD = ${TOML_HEAD}"
+- |
+  if [[ "${WITH_ASAN}" != "ON" ]]; then
+    export WITH_ASAN="OFF"
+  fi
+- echo "WITH_ASAN = ${WITH_ASAN}"
+- |
+  if [[ "${WITH_UBSAN}" != "ON" ]]; then
+    export WITH_UBSAN="OFF"
+  fi
+- echo "WITH_UBSAN = ${WITH_UBSAN}"
 - cmake --version
 - mkdir build
 - cd build
-- git clone https://github.com/toml-lang/toml.git
-- cmake -DCMAKE_CXX_COMPILER=$COMPILER -DCMAKE_CXX_STANDARD=$CXX_STANDARD -DTOML11_USE_UNRELEASED_TOML_FEATURES=${TOML_HEAD} ..
+- echo "COMPILER     = ${COMPILER}"
+- echo "CXX_STANDARD = ${CXX_STANDARD}"
+- cmake -DCMAKE_CXX_COMPILER=$COMPILER -DCMAKE_CXX_STANDARD=$CXX_STANDARD -DTOML11_USE_UNRELEASED_TOML_FEATURES=${TOML_HEAD} -Dtoml11_TEST_WITH_ASAN=${WITH_ASAN} -Dtoml11_TEST_WITH_UBSAN=${WITH_UBSAN} ..
 - make
 - ctest --output-on-failure
-
-# https://stackoverflow.com/a/53331571
-before_cache:
-- |
-  if [[ "${TRAVIS_OS_NAME}" == "osx" ]]; then
-    brew cleanup
-  fi

CMakeLists.txt

@@ -1,24 +1,17 @@
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.1)
 enable_testing()
 
-project(toml11)
-
-set(toml11_VERSION_MAYOR  3)
-set(toml11_VERSION_MINOR  2)
-set(toml11_VERSION_PATCH  0)
-set(toml11_VERSION
-  "${toml11_VERSION_MAYOR}.${toml11_VERSION_MINOR}.${toml11_VERSION_PATCH}"
-)
+project(toml11 VERSION 3.3.1)
 
 option(toml11_BUILD_TEST "Build toml tests" ON)
+option(toml11_TEST_WITH_ASAN  "use LLVM address sanitizer" OFF)
+option(toml11_TEST_WITH_UBSAN "use LLVM undefined behavior sanitizer" OFF)
 
 include(CheckCXXCompilerFlag)
 if("${CMAKE_VERSION}" VERSION_GREATER 3.1)
-    set(CMAKE_CXX_EXTENSIONS OFF)
-    if(NOT DEFINED CMAKE_CXX_STANDARD)
-        set(CMAKE_CXX_STANDARD 11)
-    endif()
-    set(CXX_STANDARD_REQUIRED ON)
+    set(CMAKE_CXX_STANDARD 11 CACHE STRING "The C++ standard whose features are requested to build all targets.")
+    set(CMAKE_CXX_STANDARD_REQUIRED ON CACHE BOOL "Boolean describing whether the value of CXX_STANDARD is a requirement.")
+    set(CMAKE_CXX_EXTENSIONS OFF CACHE BOOL "Boolean specifying whether compiler specific extensions are requested.")
 else()
     # Manually check for C++11 compiler flag.
     CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)

README.md

@@ -8,16 +8,17 @@ toml11
 [![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)
 
-toml11 is a C++11 header-only toml parser/encoder depending only on C++ standard library.
+toml11 is a C++11 (or later) 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.
-
-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).
+- It is 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).
+- It optionally supports the [unreleased features](#unreleased-toml-features) in the master branch of toml-lang/toml.
+- It is one of the most TOML standard compliant libraries, tested with [the language agnostic test suite for TOML parsers by BurntSushi](https://github.com/BurntSushi/toml-test).
+- It shows highly informative error messages. You can see the error messages about invalid files at [CircleCI](https://circleci.com/gh/ToruNiina/toml11).
+- It has configurable container. You can use any random-access containers and key-value maps as backend containers.
+- It optionally preserves comments without any overhead.
+- It has configurable serializer that supports comments, inline tables, literal strings and multiline strings.
+- It supports user-defined type conversion from/into toml values.
+- It correctly handles UTF-8 sequences, with or without BOM, both on posix and Windows.
 
 ## Example
 
@@ -27,15 +28,25 @@ You can see the error messages about invalid files and serialization results of
 
 int main()
 {
-    const auto data = toml::parse("example.toml");
+    auto data = toml::parse("example.toml");
 
-    // title = "an example toml file"
+    // find a value with the specified type from a table
     std::string title = toml::find<std::string>(data, "title");
-    std::cout << "the title is " << title << std::endl;
 
-    // nums = [1, 2, 3, 4, 5]
-    std::vector<int> nums  = toml::find<std::vector<int>>(data, "nums");
-    std::cout << "the length of `nums` is" << nums.size() << std::endl;
+    // convert the whole array into any container automatically
+    std::vector<int> nums = toml::find<std::vector<int>>(data, "nums");
+
+    // access with STL-like manner
+    if(not data.at("a").contains("b"))
+    {
+        data["a"]["b"] = "c";
+    }
+
+    // pass a fallback
+    std::string name = toml::find_or<std::string>(data, "name", "not found");
+
+    // width-dependent formatting
+    std::cout << std::setw(80) << data << std::endl;
 
     return 0;
 }
@@ -274,10 +285,44 @@ const auto color = toml::find<std::string>(data, "fruit", "physical", "color");
 const auto shape = toml::find<std::string>(data, "fruit", "physical", "shape");
 ```
 
+### Finding a value in an array
+
+You can find n-th value in an array by `toml::find`.
+
+```toml
+values = ["foo", "bar", "baz"]
+```
+
+``` cpp
+const auto data   = toml::parse("sample.toml");
+const auto values = toml::find(data, "values");
+const auto bar    = toml::find<std::string>(values, 1);
+```
+
+`toml::find` can also search array recursively.
+
+```cpp
+const auto data = toml::parse("fruit.toml");
+const auto bar  = toml::find<std::string>(data, "values", 1);
+```
+
+Before calling `toml::find`, you can check if a value corresponding to a key
+exists. You can use both `bool toml::value::contains(const key&) const` and
+`std::size_t toml::value::count(const key&) const`. Those behaves like the
+`std::map::contains` and `std::map::count`.
+
+```cpp
+const auto data = toml::parse("fruit.toml");
+if(data.contains("fruit") && data.at("fruit").count("physical") != 0)
+{
+    // ...
+}
+```
+
 ### In case of error
 
-If the value does not exist, `toml::find` throws an error with the location of
-the table.
+If the value does not exist, `toml::find` throws `std::out_of_range` with the
+location of the table.
 
 ```console
 terminate called after throwing an instance of 'std::out_of_range'
@@ -287,11 +332,6 @@ terminate called after throwing an instance of 'std::out_of_range'
    | ~~~~~ in this table
 ```
 
-**Note**: It is recommended to find a table as `toml::value` because it has much information
-compared to `toml::table`, which is an alias of
-`std::unordered_map<std::string, toml::value>`. Since `toml::table` does not have
-any information about toml file, such as where the table was defined in the file.
-
 ----
 
 If the specified type differs from the actual value contained, it throws
@@ -869,14 +909,25 @@ toml::value v(toml::local_time(std::chrono::hours(10)));
 ```
 
 You can construct an array object not only from `initializer_list`, but also
-from STL containers.
+from STL containers. In that case, the element type must be convertible to
+`toml::value`.
 
 ```cpp
 std::vector<int> vec{1,2,3,4,5};
-toml::value v = vec;
+toml::value v(vec);
 ```
 
-All the elements of `initializer_list` should be convertible into `toml::value`.
+When you construct an array value, all the elements of `initializer_list`
+must be convertible into `toml::value`.
+
+If a `toml::value` has an array, you can `push_back` an element in it.
+
+```cpp
+toml::value v{1,2,3,4,5};
+v.push_back(6);
+```
+
+`emplace_back` also works.
 
 ## Preserving comments
 
@@ -1093,7 +1144,7 @@ const auto data = toml::parse("example.toml");
 const foo f = toml::find<ext::foo>(data, "foo");
 ```
 
-There are 2 ways to use `toml::get` with the types that you defined.
+There are 3 ways to use `toml::get` with the types that you defined.
 
 The first one is to implement `from_toml(const toml::value&)` member function.
 
@@ -1120,7 +1171,31 @@ struct foo
 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.
+The second is to implement `constructor(const toml::value&)`.
+
+```cpp
+namespace ext
+{
+struct foo
+{
+    explicit foo(const toml::value& v)
+        : a(toml::find<int>(v, "a")), b(toml::find<double>(v, "b")),
+          c(toml::find<std::string>(v, "c"))
+    {}
+
+    int         a;
+    double      b;
+    std::string c;
+};
+} // ext
+```
+
+Note that implicit default constructor declaration will be suppressed
+when a constructor is defined. If you want to use the struct (here, `foo`)
+in a container (e.g. `std::vector<foo>`), you may need to define default
+constructor explicitly.
+
+The third is to implement specialization of `toml::from` for your type.
 
 ```cpp
 namespace ext
@@ -1349,7 +1424,7 @@ const toml::source_location loc = v.location();
 
 ## Exceptions
 
-All the exceptions thrown by toml11 inherits `toml::exception` that inherits
+The following `exception` classes inherits `toml::exception` that inherits
 `std::exception`.
 
 ```cpp
@@ -1376,6 +1451,16 @@ struct exception : public std::exception
 
 It represents where the error occurs.
 
+`syntax_error` will be thrown from `toml::parse` and `_toml` literal.
+`type_error` will be thrown from `toml::get/find`, `toml::value::as_xxx()`, and
+other functions that takes a content inside of `toml::value`.
+
+Note that, currently, from `toml::value::at()` and `toml::find(value, key)`
+may throw an `std::out_of_range` that does not inherits `toml::exception`.
+
+Also, in some cases, most likely in the file open error, it will throw an
+`std::runtime_error`.
+
 ## Colorize Error Messages
 
 By defining `TOML11_COLORIZE_ERROR_MESSAGE`, the error messages from
@@ -1679,13 +1764,12 @@ Such a big change will not happen in the coming years.
 
 ## 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.
+After cloning this repository, run the following command (thank you @jwillikers
+for automating test set fetching!).
 
 ```sh
 $ mkdir build
 $ cd build
-$ git clone https://github.com/toml-lang/toml.git
 $ cmake ..
 $ make
 $ make test
@@ -1719,11 +1803,16 @@ I appreciate the help of the contributors who introduced the great feature to th
   - Suppress warnings in Debug mode
 - OGAWA Kenichi (@kenichiice)
   - Suppress warnings on intel compiler
+- Jordan Williams (@jwillikers)
+  - Fixed clang range-loop-analysis warnings
+  - Fixed feature test macro to suppress -Wundef
+  - Use cache variables in CMakeLists.txt
+  - Automate test set fetching, update and refactor CMakeLists.txt
 
 ## Licensing terms
 
 This product is licensed under the terms of the [MIT License](LICENSE).
 
-- Copyright (c) 2017-2019 Toru Niina
+- Copyright (c) 2017-2020 Toru Niina
 
 All rights reserved.

appveyor.yml

@@ -17,10 +17,9 @@ build_script:
   - cd C:\toml11
   - mkdir build
   - cd build
-  - git clone https://github.com/toml-lang/toml.git
-  - file --mime-encoding toml/tests/hard_example_unicode.toml
   - cmake -G"%generator%" -DBOOST_ROOT=C:/Libraries/boost_1_69_0 ..
   - cmake --build . --config "%configuration%"
+  - file --mime-encoding tests/toml/tests/hard_example_unicode.toml
 
 test_script:
   - ctest --build-config "%configuration%" --timeout 300 --output-on-failure

tests/CMakeLists.txt

@@ -1,3 +1,12 @@
+include(ExternalProject)
+ExternalProject_Add(toml
+        SOURCE_DIR ${CMAKE_CURRENT_BINARY_DIR}/toml
+        GIT_REPOSITORY https://github.com/toml-lang/toml
+        GIT_TAG v0.5.0
+        CONFIGURE_COMMAND ""
+        BUILD_COMMAND ""
+        INSTALL_COMMAND "")
+
 set(TEST_NAMES
     test_datetime
     test_string
@@ -39,6 +48,17 @@ set(TEST_NAMES
 CHECK_CXX_COMPILER_FLAG("-Wall"      COMPILER_SUPPORTS_WALL)
 CHECK_CXX_COMPILER_FLAG("-Wextra"    COMPILER_SUPPORTS_WEXTRA)
 CHECK_CXX_COMPILER_FLAG("-Wpedantic" COMPILER_SUPPORTS_WPEDANTIC)
+CHECK_CXX_COMPILER_FLAG("-Werror"    COMPILER_SUPPORTS_WERROR)
+
+CHECK_CXX_COMPILER_FLAG("-Wsign-conversion"     COMPILER_SUPPORTS_WSIGN_CONVERSION)
+CHECK_CXX_COMPILER_FLAG("-Wconversion"          COMPILER_SUPPORTS_WCONVERSION)
+CHECK_CXX_COMPILER_FLAG("-Wduplicated-cond"     COMPILER_SUPPORTS_WDUPLICATED_COND)
+CHECK_CXX_COMPILER_FLAG("-Wduplicated-branches" COMPILER_SUPPORTS_WDUPLICATED_BRANCHES)
+CHECK_CXX_COMPILER_FLAG("-Wlogical-op"          COMPILER_SUPPORTS_WLOGICAL_OP)
+CHECK_CXX_COMPILER_FLAG("-Wuseless-cast"        COMPILER_SUPPORTS_WUSELESS_CAST)
+CHECK_CXX_COMPILER_FLAG("-Wdouble-promotion"    COMPILER_SUPPORTS_WDOUBLE_PROMOTION)
+CHECK_CXX_COMPILER_FLAG("-Wrange-loop-analysis" COMPILER_SUPPORTS_WRANGE_LOOP_ANALYSIS)
+CHECK_CXX_COMPILER_FLAG("-Wundef"               COMPILER_SUPPORTS_WUNDEF)
 
 if(COMPILER_SUPPORTS_WALL)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall")
@@ -49,6 +69,36 @@ endif()
 if(COMPILER_SUPPORTS_WPEDANTIC)
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wpedantic")
 endif()
+if(COMPILER_SUPPORTS_WERROR)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror")
+endif()
+if(COMPILER_SUPPORTS_WSIGN_CONVERSION)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wsign-conversion")
+endif()
+if(COMPILER_SUPPORTS_WCONVERSION)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wconversion")
+endif()
+if(COMPILER_SUPPORTS_WDUPLICATED_COND)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wduplicated-cond")
+endif()
+if(COMPILER_SUPPORTS_WDUPLICATED_BRANCHES)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wduplicated-branches")
+endif()
+if(COMPILER_SUPPORTS_WLOGICAL_OP)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wlogical-op")
+endif()
+if(COMPILER_SUPPORTS_WUSELESS_CAST)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wuseless-cast")
+endif()
+if(COMPILER_SUPPORTS_WDOUBLE_PROMOTION)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wdouble-promotion")
+endif()
+if(COMPILER_SUPPORTS_WRANGE_LOOP_ANALYSIS)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wrange-loop-analysis")
+endif()
+if(COMPILER_SUPPORTS_WUNDEF)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wundef")
+endif()
 
 option(TOML11_USE_UNRELEASED_TOML_FEATURES
     "use features in toml-lang/toml master while testing" OFF)
@@ -104,7 +154,20 @@ foreach(TEST_NAME ${TEST_NAMES})
     add_executable(${TEST_NAME} ${TEST_NAME}.cpp)
     target_link_libraries(${TEST_NAME} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY} toml11::toml11)
     target_include_directories(${TEST_NAME} PRIVATE ${Boost_INCLUDE_DIRS})
-    add_test(NAME ${TEST_NAME} COMMAND ${TEST_NAME} WORKING_DIRECTORY ${PROJECT_BINARY_DIR})
+
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+        if(toml11_TEST_WITH_ASAN)
+            set_target_properties(${TEST_NAME} PROPERTIES
+                COMPILE_FLAGS "-fsanitize=address -fno-omit-frame-pointer"
+                LINK_FLAGS    "-fsanitize=address -fno-omit-frame-pointer")
+        elseif(toml11_TEST_WITH_UBSAN)
+            set_target_properties(${TEST_NAME} PROPERTIES
+                COMPILE_FLAGS "-fsanitize=undefined"
+                LINK_FLAGS    "-fsanitize=undefined")
+        endif()
+    endif()
+
+    add_test(NAME ${TEST_NAME} COMMAND ${TEST_NAME} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
 
     # Set the PATH to be able to find Boost DLL
     if(WIN32)

tests/check_toml_test.cpp

@@ -84,9 +84,7 @@ struct json_serializer
         {
             if(!is_first) {std::cout << ", ";}
             is_first = false;
-            std::cout << toml::format(toml::value(elem.first),
-                    std::numeric_limits<std::size_t>::max());
-            std::cout << ':';
+            std::cout << this->format_key(elem.first) << ':';
             toml::visit(*this, elem.second);
         }
         std::cout << '}';
@@ -112,6 +110,12 @@ struct json_serializer
         }
         return retval;
     }
+
+    std::string format_key(const std::string& s) const
+    {
+        const auto quote("\"");
+        return quote + escape_string(s) + quote;
+    }
 };
 
 int main()

tests/test_extended_conversions.cpp

@@ -44,6 +44,18 @@ struct qux
     int a;
     std::string b;
 };
+
+struct foobar
+{
+    foobar() = default; // later we use std::vector<foobar>, default ctor is required.
+
+    // via constructor
+    explicit foobar(const toml::value& v)
+        : a(toml::find<int>(v, "a")), b(toml::find<std::string>(v, "b"))
+    {}
+    int a;
+    std::string b;
+};
 } // extlib
 
 namespace toml
@@ -122,6 +134,19 @@ struct qux
     int a;
     std::string b;
 };
+
+struct foobar
+{
+    foobar() = default; // later we use std::vector<foobar>, default ctor is required.
+
+    template<typename C, template<typename ...> class M, template<typename ...> class A>
+    explicit foobar(const toml::basic_value<C, M, A>& v)
+        : a(toml::find<int>(v, "a")), b(toml::find<std::string>(v, "b"))
+    {}
+    int a;
+    std::string b;
+};
+
 } // extlib2
 
 namespace toml
@@ -284,6 +309,27 @@ BOOST_AUTO_TEST_CASE(test_conversion_one_way)
     }
 }
 
+BOOST_AUTO_TEST_CASE(test_conversion_via_constructor)
+{
+    {
+        const toml::value v{{"a", 42}, {"b", "foobar"}};
+
+        const auto foobar = toml::get<extlib::foobar>(v);
+        BOOST_TEST(foobar.a == 42);
+        BOOST_TEST(foobar.b == "foobar");
+    }
+
+    {
+        const toml::basic_value<toml::discard_comments, std::map> v{
+            {"a", 42}, {"b", "foobar"}
+        };
+
+        const auto foobar = toml::get<extlib2::foobar>(v);
+        BOOST_TEST(foobar.a == 42);
+        BOOST_TEST(foobar.b == "foobar");
+    }
+}
+
 BOOST_AUTO_TEST_CASE(test_recursive_conversion)
 {
     {
@@ -384,5 +430,63 @@ BOOST_AUTO_TEST_CASE(test_recursive_conversion)
         BOOST_TEST(bars.at(2).b == "quux");
         BOOST_TEST(bars.at(3).b == "foobar");
     }
+
+    // via constructor
+    {
+        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 foobars = toml::get<std::vector<extlib::foobar>>(v);
+            BOOST_TEST(foobars.size()  == 4ul);
+            BOOST_TEST(foobars.at(0).a == 42);
+            BOOST_TEST(foobars.at(1).a == 43);
+            BOOST_TEST(foobars.at(2).a == 44);
+            BOOST_TEST(foobars.at(3).a == 45);
+
+            BOOST_TEST(foobars.at(0).b == "baz");
+            BOOST_TEST(foobars.at(1).b == "qux");
+            BOOST_TEST(foobars.at(2).b == "quux");
+            BOOST_TEST(foobars.at(3).b == "foobar");
+        }
+        {
+            const auto foobars = toml::get<std::vector<extlib2::foobar>>(v);
+            BOOST_TEST(foobars.size()  == 4ul);
+            BOOST_TEST(foobars.at(0).a == 42);
+            BOOST_TEST(foobars.at(1).a == 43);
+            BOOST_TEST(foobars.at(2).a == 44);
+            BOOST_TEST(foobars.at(3).a == 45);
+
+            BOOST_TEST(foobars.at(0).b == "baz");
+            BOOST_TEST(foobars.at(1).b == "qux");
+            BOOST_TEST(foobars.at(2).b == "quux");
+            BOOST_TEST(foobars.at(3).b == "foobar");
+        }
+    }
+    {
+        const toml::basic_value<toml::discard_comments, std::map, std::deque>
+            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 foobars = toml::get<std::vector<extlib2::foobar>>(v);
+        BOOST_TEST(foobars.size()  == 4ul);
+        BOOST_TEST(foobars.at(0).a == 42);
+        BOOST_TEST(foobars.at(1).a == 43);
+        BOOST_TEST(foobars.at(2).a == 44);
+        BOOST_TEST(foobars.at(3).a == 45);
+
+        BOOST_TEST(foobars.at(0).b == "baz");
+        BOOST_TEST(foobars.at(1).b == "qux");
+        BOOST_TEST(foobars.at(2).b == "quux");
+        BOOST_TEST(foobars.at(3).b == "foobar");
+    }
 }
 

tests/test_find.cpp

@@ -101,6 +101,78 @@ BOOST_AUTO_TEST_CASE(test_find_throws)
     }
 }
 
+BOOST_AUTO_TEST_CASE(test_find_array_throws)
+{
+    // -----------------------------------------------------------------------
+    // const-reference version
+    {
+        // value is not an array
+        const toml::value v(true);
+        BOOST_CHECK_THROW(toml::find<toml::boolean>(v, 0), toml::type_error);
+    }
+    {
+        // the value corresponding to the key is not the expected type
+        const toml::value v{1, 2, 3, 4, 5};
+        BOOST_CHECK_THROW(toml::find<toml::boolean>(v, 0), toml::type_error);
+    }
+    {
+        // the value corresponding to the key is not found
+        const toml::value v{1, 2, 3, 4, 5};
+        BOOST_CHECK_THROW(toml::find<toml::integer>(v, 6), std::out_of_range);
+    }
+    {
+        // the positive control.
+        const toml::value v{1, 2, 3, 4, 5};
+        BOOST_TEST(3 == toml::find<int>(v, 2));
+    }
+
+    // -----------------------------------------------------------------------
+    // non-const reference version
+    {
+        // value is not an array
+        toml::value v(true);
+        BOOST_CHECK_THROW(toml::find<toml::boolean>(v, 0), toml::type_error);
+    }
+    {
+        // the value corresponding to the key is not the expected type
+        toml::value v{1, 2, 3, 4, 5};
+        BOOST_CHECK_THROW(toml::find<toml::boolean>(v, 0), toml::type_error);
+    }
+    {
+        // the value corresponding to the key is not found
+        toml::value v{1, 2, 3, 4, 5};
+        BOOST_CHECK_THROW(toml::find<toml::integer>(v, 6), std::out_of_range);
+    }
+    {
+        // the positive control.
+        toml::value v{1, 2, 3, 4, 5};
+        BOOST_TEST(3 == toml::find<int>(v, 2));
+    }
+
+    // -----------------------------------------------------------------------
+    // move version
+    {
+        // value is not an array
+        toml::value v(true);
+        BOOST_CHECK_THROW(toml::find<toml::boolean>(std::move(v), 0), toml::type_error);
+    }
+    {
+        // the value corresponding to the key is not the expected type
+        toml::value v{1, 2, 3, 4, 5};
+        BOOST_CHECK_THROW(toml::find<toml::boolean>(std::move(v), 0), toml::type_error);
+    }
+    {
+        // the value corresponding to the key is not found
+        toml::value v{1, 2, 3, 4, 5};
+        BOOST_CHECK_THROW(toml::find<toml::integer>(std::move(v), 6), std::out_of_range);
+    }
+    {
+        // the positive control.
+        toml::value v{1, 2, 3, 4, 5};
+        BOOST_TEST(3 == toml::find<int>(std::move(v), 2));
+    }
+}
+
 BOOST_AUTO_TEST_CASE(test_find_recursive)
 {
     // recursively search tables
@@ -126,8 +198,76 @@ BOOST_AUTO_TEST_CASE(test_find_recursive)
         num2 = 42;
         BOOST_TEST(42 == toml::find<int>(v, a, b, c, d));
 
-        auto num3 = toml::find<toml::integer>(std::move(v), a, b, c, d);
+        auto num3 = toml::find<toml::integer>(v, a, "b", c, "d");
         BOOST_TEST(42 == num3);
+
+        auto num4 = toml::find<toml::integer>(std::move(v), a, b, c, d);
+        BOOST_TEST(42 == num4);
+    }
+    // recursively search arrays
+    {
+        toml::value v{
+            toml::array{"array", "of", "string"},
+            toml::array{toml::array{1, 2, 3}, toml::array{3.14, 2.71}}
+        };
+        BOOST_TEST("array"  == toml::find<std::string>(v, 0, 0));
+        BOOST_TEST("of"     == toml::find<std::string>(v, 0, 1));
+        BOOST_TEST("string" == toml::find<std::string>(v, 0, 2));
+
+        BOOST_TEST(1 == toml::find<int>(v, 1, 0, 0));
+        BOOST_TEST(2 == toml::find<int>(v, 1, 0, 1));
+        BOOST_TEST(3 == toml::find<int>(v, 1, 0, 2));
+
+        BOOST_TEST(3.14 == toml::find<double>(v, 1, 1, 0));
+        BOOST_TEST(2.71 == toml::find<double>(v, 1, 1, 1));
+
+        // reference that can be used to modify the content
+        auto& num = toml::find<toml::integer>(v, 1, 0, 2);
+        num = 42;
+        BOOST_TEST( 1 == toml::find<int>(v, 1, 0, 0));
+        BOOST_TEST( 2 == toml::find<int>(v, 1, 0, 1));
+        BOOST_TEST(42 == toml::find<int>(v, 1, 0, 2));
+
+        // move value
+        auto num2 = toml::find<toml::integer>(std::move(v), 1, 0, 2);
+        BOOST_TEST(42 == num2);
+    }
+    // recursively search mixtures
+    {
+        toml::value v = toml::table{{"array", toml::array{
+                toml::array{1,   2,   3},
+                toml::array{
+                    toml::table{{"foo", "bar"}, {"baz", "qux"}},
+                    toml::table{{"pi",   3.14}, {"e",    2.71}}
+                }}
+            }};
+
+        BOOST_TEST(1 == toml::find<int>(v, "array", 0, 0));
+        BOOST_TEST(2 == toml::find<int>(v, "array", 0, 1));
+        BOOST_TEST(3 == toml::find<int>(v, "array", 0, 2));
+
+        BOOST_TEST("bar" == toml::find<std::string>(v, "array", 1, 0, "foo"));
+        BOOST_TEST("qux" == toml::find<std::string>(v, "array", 1, 0, "baz"));
+
+        BOOST_TEST(3.14 == toml::find<double>(v, "array", 1, 1, "pi"));
+        BOOST_TEST(2.71 == toml::find<double>(v, "array", 1, 1, "e"));
+
+        const std::string ar("array");
+        const auto ar_c = "array";
+
+        const std::string pi("pi");
+        const auto pi_c = "pi";
+
+        BOOST_TEST(3.14 == toml::find<double>(v, ar, 1, 1, "pi"));
+        BOOST_TEST(3.14 == toml::find<double>(v, ar, 1, 1, pi));
+        BOOST_TEST(3.14 == toml::find<double>(v, ar, 1, 1, pi_c));
+
+        BOOST_TEST(3.14 == toml::find<double>(v, ar_c, 1, 1, "pi"));
+        BOOST_TEST(3.14 == toml::find<double>(v, ar_c, 1, 1, pi));
+        BOOST_TEST(3.14 == toml::find<double>(v, ar_c, 1, 1, pi_c));
+
+        BOOST_TEST(3.14 == toml::find<double>(v, "array", 1, 1, pi));
+        BOOST_TEST(3.14 == toml::find<double>(v, "array", 1, 1, pi_c));
     }
 }
 
@@ -309,10 +449,11 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_find_floating_type, value_type, test_value_ty
 {
     {
         value_type v{{"key", 3.14}};
-        BOOST_TEST(static_cast<float      >(3.14) == toml::find<float      >(v, "key"));
-        BOOST_TEST(static_cast<double     >(3.14) == toml::find<double     >(v, "key"));
-        BOOST_TEST(static_cast<long double>(3.14) == toml::find<long double>(v, "key"));
-        BOOST_TEST(static_cast<float      >(3.14) == toml::find<float      >(std::move(v), "key"));
+        const double ref(3.14);
+        BOOST_TEST(static_cast<float      >(ref) == toml::find<float      >(v, "key"));
+        BOOST_TEST(                         ref  == toml::find<double     >(v, "key"));
+        BOOST_TEST(static_cast<long double>(ref) == toml::find<long double>(v, "key"));
+        BOOST_TEST(static_cast<float      >(ref) == toml::find<float      >(std::move(v), "key"));
     }
 }
 
@@ -373,14 +514,14 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_find_toml_array, value_type, test_value_types
     BOOST_TEST(static_cast<std::int64_t>(72) == deq.at(3));
 
     std::array<int, 4> ary = toml::find<std::array<int, 4>>(v, "key");
-    BOOST_TEST(static_cast<int>(42) == ary.at(0));
-    BOOST_TEST(static_cast<int>(54) == ary.at(1));
-    BOOST_TEST(static_cast<int>(69) == ary.at(2));
-    BOOST_TEST(static_cast<int>(72) == ary.at(3));
+    BOOST_TEST(42 == ary.at(0));
+    BOOST_TEST(54 == ary.at(1));
+    BOOST_TEST(69 == ary.at(2));
+    BOOST_TEST(72 == ary.at(3));
 
     std::tuple<int, short, unsigned, long> tpl =
         toml::find<std::tuple<int, short, unsigned, long>>(v, "key");
-    BOOST_TEST(static_cast<int     >(42) == std::get<0>(tpl));
+    BOOST_TEST(                      42  == std::get<0>(tpl));
     BOOST_TEST(static_cast<short   >(54) == std::get<1>(tpl));
     BOOST_TEST(static_cast<unsigned>(69) == std::get<2>(tpl));
     BOOST_TEST(static_cast<long    >(72) == std::get<3>(tpl));
@@ -420,14 +561,14 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_find_move_toml_array, value_type, test_value_
     BOOST_TEST(static_cast<std::int64_t>(72) == deq.at(3));
 
     std::array<int, 4> ary = toml::find<std::array<int, 4>>(std::move(v4), "key");
-    BOOST_TEST(static_cast<int>(42) == ary.at(0));
-    BOOST_TEST(static_cast<int>(54) == ary.at(1));
-    BOOST_TEST(static_cast<int>(69) == ary.at(2));
-    BOOST_TEST(static_cast<int>(72) == ary.at(3));
+    BOOST_TEST(42 == ary.at(0));
+    BOOST_TEST(54 == ary.at(1));
+    BOOST_TEST(69 == ary.at(2));
+    BOOST_TEST(72 == ary.at(3));
 
     std::tuple<int, short, unsigned, long> tpl =
         toml::find<std::tuple<int, short, unsigned, long>>(std::move(v5), "key");
-    BOOST_TEST(static_cast<int     >(42) == std::get<0>(tpl));
+    BOOST_TEST(                      42  == std::get<0>(tpl));
     BOOST_TEST(static_cast<short   >(54) == std::get<1>(tpl));
     BOOST_TEST(static_cast<unsigned>(69) == std::get<2>(tpl));
     BOOST_TEST(static_cast<long    >(72) == std::get<3>(tpl));

tests/test_find_or.cpp

@@ -375,7 +375,8 @@ BOOST_AUTO_TEST_CASE(test_find_or_floating)
         toml::value v1{{"key", 42}};
         toml::value v2{{"key", 3.14}};
         BOOST_TEST(2.71f == toml::find_or(v1, "key", 2.71f));
-        BOOST_TEST(static_cast<float>(double(3.14)) == toml::find_or(v2, "key", 2.71f));
+        const double ref(3.14);
+        BOOST_TEST(static_cast<float>(ref) == toml::find_or(v2, "key", 2.71f));
     }
     {
         toml::value v1{{"key", 42}};
@@ -383,7 +384,8 @@ BOOST_AUTO_TEST_CASE(test_find_or_floating)
         const auto moved1 = toml::find_or(std::move(v1), "key", 2.71f);
         const auto moved2 = toml::find_or(std::move(v2), "key", 2.71f);
         BOOST_TEST(2.71f == moved1);
-        BOOST_TEST(static_cast<float>(double(3.14)) == moved2);
+        const double ref(3.14);
+        BOOST_TEST(static_cast<float>(ref) == moved2);
     }
 }
 

tests/test_get.cpp

@@ -195,11 +195,11 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_get_floating_type, value_type, test_value_typ
 {
     {
         value_type v(3.14);
-        BOOST_TEST(static_cast<float      >(3.14) == toml::get<float      >(v));
-        BOOST_TEST(static_cast<double     >(3.14) == toml::get<double     >(v));
-        BOOST_TEST(static_cast<long double>(3.14) == toml::get<long double>(v));
-
-        BOOST_TEST(3.14f == toml::get<float>(std::move(v)));
+        const double ref(3.14);
+        BOOST_TEST(static_cast<float      >(ref) == toml::get<float      >(v));
+        BOOST_TEST(                         ref  == toml::get<double     >(v));
+        BOOST_TEST(static_cast<long double>(ref) == toml::get<long double>(v));
+        BOOST_TEST(static_cast<float      >(ref) == toml::get<float>(std::move(v)));
     }
 }
 
@@ -262,14 +262,14 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_get_toml_array, value_type, test_value_types)
         BOOST_TEST(static_cast<std::int64_t>(72) == deq.at(3));
 
         std::array<int, 4> ary = toml::get<std::array<int, 4>>(v);
-        BOOST_TEST(static_cast<int>(42) == ary.at(0));
-        BOOST_TEST(static_cast<int>(54) == ary.at(1));
-        BOOST_TEST(static_cast<int>(69) == ary.at(2));
-        BOOST_TEST(static_cast<int>(72) == ary.at(3));
+        BOOST_TEST(42 == ary.at(0));
+        BOOST_TEST(54 == ary.at(1));
+        BOOST_TEST(69 == ary.at(2));
+        BOOST_TEST(72 == ary.at(3));
 
         std::tuple<int, short, unsigned, long> tpl =
             toml::get<std::tuple<int, short, unsigned, long>>(v);
-        BOOST_TEST(static_cast<int     >(42) == std::get<0>(tpl));
+        BOOST_TEST(                      42  == std::get<0>(tpl));
         BOOST_TEST(static_cast<short   >(54) == std::get<1>(tpl));
         BOOST_TEST(static_cast<unsigned>(69) == std::get<2>(tpl));
         BOOST_TEST(static_cast<long    >(72) == std::get<3>(tpl));
@@ -308,16 +308,16 @@ BOOST_AUTO_TEST_CASE_TEMPLATE(test_get_toml_array, value_type, test_value_types)
     {
         value_type v{42, 54, 69, 72};
         std::array<int, 4> ary = toml::get<std::array<int, 4>>(std::move(v));
-        BOOST_TEST(static_cast<int>(42) == ary.at(0));
-        BOOST_TEST(static_cast<int>(54) == ary.at(1));
-        BOOST_TEST(static_cast<int>(69) == ary.at(2));
-        BOOST_TEST(static_cast<int>(72) == ary.at(3));
+        BOOST_TEST(42 == ary.at(0));
+        BOOST_TEST(54 == ary.at(1));
+        BOOST_TEST(69 == ary.at(2));
+        BOOST_TEST(72 == ary.at(3));
     }
     {
         value_type v{42, 54, 69, 72};
         std::tuple<int, short, unsigned, long> tpl =
             toml::get<std::tuple<int, short, unsigned, long>>(std::move(v));
-        BOOST_TEST(static_cast<int     >(42) == std::get<0>(tpl));
+        BOOST_TEST(                      42  == std::get<0>(tpl));
         BOOST_TEST(static_cast<short   >(54) == std::get<1>(tpl));
         BOOST_TEST(static_cast<unsigned>(69) == std::get<2>(tpl));
         BOOST_TEST(static_cast<long    >(72) == std::get<3>(tpl));

tests/test_lex_string.cpp

@@ -57,6 +57,22 @@ BOOST_AUTO_TEST_CASE(test_ml_basic_string)
     TOML11_TEST_LEX_ACCEPT(lex_string,
         "\"\"\"\\\n  The quick brown \\\n\n  fox jumps over \\\n  the lazy dog.\\\n  \"\"\"",
         "\"\"\"\\\n  The quick brown \\\n\n  fox jumps over \\\n  the lazy dog.\\\n  \"\"\"");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "\"\"\"Here are two quotation marks: \"\". Simple enough.\"\"\"",
+        "\"\"\"Here are two quotation marks: \"\". Simple enough.\"\"\"");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "\"\"\"Here are three quotation marks: \"\"\\\".\"\"\"",
+        "\"\"\"Here are three quotation marks: \"\"\\\".\"\"\"");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "\"\"\"Here are fifteen quotation marks: \"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\".\"\"\"",
+        "\"\"\"Here are fifteen quotation marks: \"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\".\"\"\"");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "\"\"\"\"This,\" she said, \"is just a pointless statement.\"\"\"\"",
+        "\"\"\"\"This,\" she said, \"is just a pointless statement.\"\"\"\"");
 }
 
 BOOST_AUTO_TEST_CASE(test_literal_string)
@@ -83,4 +99,16 @@ BOOST_AUTO_TEST_CASE(test_ml_literal_string)
     TOML11_TEST_LEX_ACCEPT(lex_string,
         "'''\nThe first newline is\ntrimmed in raw strings.\n   All other whitespace\n   is preserved.\n'''",
         "'''\nThe first newline is\ntrimmed in raw strings.\n   All other whitespace\n   is preserved.\n'''");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "''''That's still pointless', she said.'''",
+        "''''That's still pointless', she said.'''");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "'''Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".'''",
+        "'''Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".'''");
+
+    TOML11_TEST_LEX_ACCEPT(lex_string,
+        "''''This,' she said, 'is just a pointless statement.''''",
+        "''''This,' she said, 'is just a pointless statement.''''");
 }

tests/test_parse_string.cpp

@@ -29,16 +29,16 @@ BOOST_AUTO_TEST_CASE(test_string)
 
 BOOST_AUTO_TEST_CASE(test_string_value)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"The quick brown fox jumps over the lazy dog\"",
         toml::value("The quick brown fox jumps over the lazy dog", string_t::basic));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\'The quick brown fox jumps over the lazy dog\'",
         toml::value("The quick brown fox jumps over the lazy dog", string_t::literal));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"\"\"The quick brown fox \\\njumps over the lazy dog\"\"\"",
         toml::value("The quick brown fox jumps over the lazy dog", string_t::basic));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'''The quick brown fox \njumps over the lazy dog'''",
         toml::value("The quick brown fox \njumps over the lazy dog", string_t::literal));
 }
@@ -69,14 +69,17 @@ BOOST_AUTO_TEST_CASE(test_basic_string)
     TOML11_TEST_PARSE_EQUAL(parse_string,
         "\" And when \\\"'s are in the along with # \\\"\"",
         string(" And when \"'s are in the along with # \"", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "\"Here are fifteen apostrophes: '''''''''''''''\"",
+        string("Here are fifteen apostrophes: '''''''''''''''", string_t::basic));
 }
 
 BOOST_AUTO_TEST_CASE(test_basic_string_value)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"GitHub Cofounder & CEO\\nLikes tater tots and beer.\"",
         value("GitHub Cofounder & CEO\nLikes tater tots and beer.", string_t::basic));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"192.168.1.1\"",
         value("192.168.1.1", string_t::basic));
 #if defined(_MSC_VER) || defined(__INTEL_COMPILER)
@@ -84,16 +87,19 @@ BOOST_AUTO_TEST_CASE(test_basic_string_value)
         "\"\xE4\xB8\xAD\xE5\x9B\xBD\"",
         value("\xE4\xB8\xAD\xE5\x9B\xBD", string_t::basic));
 #else
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"中国\"",
         value("中国", string_t::basic));
 #endif
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"You'll hate me after this - #\"",
         value("You'll hate me after this - #", string_t::basic));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\" And when \\\"'s are in the along with # \\\"\"",
         value(" And when \"'s are in the along with # \"", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "\"Here are fifteen apostrophes: '''''''''''''''\"",
+        value("Here are fifteen apostrophes: '''''''''''''''", string_t::basic));
 }
 
 BOOST_AUTO_TEST_CASE(test_ml_basic_string)
@@ -104,16 +110,41 @@ BOOST_AUTO_TEST_CASE(test_ml_basic_string)
     TOML11_TEST_PARSE_EQUAL(parse_string,
         "\"\"\"\\\n  The quick brown \\\n\n  fox jumps over \\\n  the lazy dog.\\\n  \"\"\"",
         string("The quick brown fox jumps over the lazy dog.", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "\"\"\"Here are two quotation marks: \"\". Simple enough.\"\"\"",
+        string("Here are two quotation marks: \"\". Simple enough.", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "\"\"\"Here are three quotation marks: \"\"\\\".\"\"\"",
+        string("Here are three quotation marks: \"\"\".", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "\"\"\"Here are fifteen quotation marks: \"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\".\"\"\"",
+        string("Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "\"\"\"\"This,\" she said, \"is just a pointless statement.\"\"\"\"",
+        string("\"This,\" she said, \"is just a pointless statement.\"", string_t::basic));
 }
 
 BOOST_AUTO_TEST_CASE(test_ml_basic_string_value)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"\"\"\nThe quick brown \\\n\n  fox jumps over \\\n  the lazy dog.\"\"\"",
         value("The quick brown fox jumps over the lazy dog.", string_t::basic));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "\"\"\"\\\n  The quick brown \\\n\n  fox jumps over \\\n  the lazy dog.\\\n  \"\"\"",
         value("The quick brown fox jumps over the lazy dog.", string_t::basic));
+
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "\"\"\"Here are two quotation marks: \"\". Simple enough.\"\"\"",
+        value("Here are two quotation marks: \"\". Simple enough.", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "\"\"\"Here are three quotation marks: \"\"\\\".\"\"\"",
+        value("Here are three quotation marks: \"\"\".", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "\"\"\"Here are fifteen quotation marks: \"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\"\"\"\\\".\"\"\"",
+        value("Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".", string_t::basic));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "\"\"\"\"This,\" she said, \"is just a pointless statement.\"\"\"\"",
+        value("\"This,\" she said, \"is just a pointless statement.\"", string_t::basic));
 }
 
 BOOST_AUTO_TEST_CASE(test_literal_string)
@@ -134,16 +165,16 @@ BOOST_AUTO_TEST_CASE(test_literal_string)
 
 BOOST_AUTO_TEST_CASE(test_literal_string_value)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'C:\\Users\\nodejs\\templates'",
         value("C:\\Users\\nodejs\\templates", string_t::literal));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'\\\\ServerX\\admin$\\system32\\'",
         value("\\\\ServerX\\admin$\\system32\\", string_t::literal));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'Tom \"Dubs\" Preston-Werner'",
         value("Tom \"Dubs\" Preston-Werner", string_t::literal));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'<\\i\\c*\\s*>'",
         value("<\\i\\c*\\s*>", string_t::literal));
 }
@@ -156,16 +187,34 @@ BOOST_AUTO_TEST_CASE(test_ml_literal_string)
     TOML11_TEST_PARSE_EQUAL(parse_string,
         "'''\nThe first newline is\ntrimmed in raw strings.\n   All other whitespace\n   is preserved.\n'''",
         string("The first newline is\ntrimmed in raw strings.\n   All other whitespace\n   is preserved.\n", string_t::literal));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "''''That's still pointless', she said.'''",
+        string("'That's still pointless', she said.", string_t::literal));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "'''Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".'''",
+        string("Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".", string_t::literal));
+    TOML11_TEST_PARSE_EQUAL(parse_string,
+        "''''This,' she said, 'is just a pointless statement.''''",
+        string("'This,' she said, 'is just a pointless statement.'", string_t::literal));
 }
 
 BOOST_AUTO_TEST_CASE(test_ml_literal_string_value)
 {
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'''I [dw]on't need \\d{2} apples'''",
         value("I [dw]on't need \\d{2} apples", string_t::literal));
-    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>, 
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
         "'''\nThe first newline is\ntrimmed in raw strings.\n   All other whitespace\n   is preserved.\n'''",
         value("The first newline is\ntrimmed in raw strings.\n   All other whitespace\n   is preserved.\n", string_t::literal));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "''''That's still pointless', she said.'''",
+        value("'That's still pointless', she said.", string_t::literal));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "'''Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".'''",
+        value("Here are fifteen quotation marks: \"\"\"\"\"\"\"\"\"\"\"\"\"\"\".", string_t::literal));
+    TOML11_TEST_PARSE_EQUAL_VALUE(parse_value<toml::value>,
+        "''''This,' she said, 'is just a pointless statement.''''",
+        value("'This,' she said, 'is just a pointless statement.'", string_t::literal));
 }
 
 BOOST_AUTO_TEST_CASE(test_unicode_escape_sequence)

tests/test_value.cpp

@@ -966,3 +966,54 @@ BOOST_AUTO_TEST_CASE(test_value_bracket)
         BOOST_CHECK_THROW(v1["foo"], toml::type_error);
     }
 }
+
+BOOST_AUTO_TEST_CASE(test_value_map_methods)
+{
+    {
+        toml::value v1{{"foo", 42}, {"bar", 3.14}, {"baz", "qux"}};
+
+        BOOST_TEST(v1.count("foo") == 1u);
+        BOOST_TEST(v1.count("bar") == 1u);
+        BOOST_TEST(v1.count("baz") == 1u);
+        BOOST_TEST(v1.count("qux") == 0u);
+
+        BOOST_TEST( v1.contains("foo"));
+        BOOST_TEST( v1.contains("bar"));
+        BOOST_TEST( v1.contains("baz"));
+        BOOST_TEST(!v1.contains("qux"));
+
+        BOOST_TEST(v1.size() == 3);
+
+        v1["qux"] = 54;
+        BOOST_TEST(v1.count("qux") == 1u);
+        BOOST_TEST(v1.contains("qux"));
+        BOOST_TEST(v1.size() == 4);
+    }
+    {
+        toml::value v1(42);
+        BOOST_CHECK_THROW(v1.size()       , toml::type_error);
+        BOOST_CHECK_THROW(v1.count("k")   , toml::type_error);
+        BOOST_CHECK_THROW(v1.contains("k"), toml::type_error);
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_value_vector_methods)
+{
+    {
+        toml::value v1{1, 2, 3, 4, 5};
+
+        BOOST_TEST(v1.size() == 5);
+
+        v1.push_back(6);
+        BOOST_TEST(v1.size() == 6);
+
+        v1.emplace_back(6);
+        BOOST_TEST(v1.size() == 7);
+    }
+    {
+        toml::value v1(42);
+        BOOST_CHECK_THROW(v1.size(),          toml::type_error);
+        BOOST_CHECK_THROW(v1.push_back(1),    toml::type_error);
+        BOOST_CHECK_THROW(v1.emplace_back(1), toml::type_error);
+    }
+}

toml/comments.hpp

@@ -81,6 +81,54 @@ struct preserve_comments
     void assign(std::initializer_list<std::string> ini)  {comments.assign(ini);}
     void assign(size_type n, const std::string& val)     {comments.assign(n, val);}
 
+    // Related to the issue #97.
+    //
+    // It is known that `std::vector::insert` and `std::vector::erase` in
+    // the standard library implementation included in GCC 4.8.5 takes
+    // `std::vector::iterator` instead of `std::vector::const_iterator`.
+    // Because of the const-correctness, we cannot convert a `const_iterator` to
+    // an `iterator`. It causes compilation error in GCC 4.8.5.
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__) && !defined(__clang__)
+#  if (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__) <= 40805
+#    define TOML11_WORKAROUND_GCC_4_8_X_STANDARD_LIBRARY_IMPLEMENTATION
+#  endif
+#endif
+
+#ifdef TOML11_WORKAROUND_GCC_4_8_X_STANDARD_LIBRARY_IMPLEMENTATION
+    iterator insert(iterator p, const std::string& x)
+    {
+        return comments.insert(p, x);
+    }
+    iterator insert(iterator p, std::string&&      x)
+    {
+        return comments.insert(p, std::move(x));
+    }
+    void insert(iterator p, size_type n, const std::string& x)
+    {
+        return comments.insert(p, n, x);
+    }
+    template<typename InputIterator>
+    void insert(iterator p, InputIterator first, InputIterator last)
+    {
+        return comments.insert(p, first, last);
+    }
+    void insert(iterator p, std::initializer_list<std::string> ini)
+    {
+        return comments.insert(p, ini);
+    }
+
+    template<typename ... Ts>
+    iterator emplace(iterator p, Ts&& ... args)
+    {
+        return comments.emplace(p, std::forward<Ts>(args)...);
+    }
+
+    iterator erase(iterator pos) {return comments.erase(pos);}
+    iterator erase(iterator first, iterator last)
+    {
+        return comments.erase(first, last);
+    }
+#else
     iterator insert(const_iterator p, const std::string& x)
     {
         return comments.insert(p, x);
@@ -114,6 +162,7 @@ struct preserve_comments
     {
         return comments.erase(first, last);
     }
+#endif
 
     void swap(preserve_comments& other) {comments.swap(other.comments);}
 

toml/datetime.hpp

@@ -20,7 +20,7 @@ namespace toml
 namespace detail
 {
 // TODO: find more sophisticated way to handle this
-#if _POSIX_C_SOURCE >= 1 || defined(_XOPEN_SOURCE) || defined(_BSD_SOURCE) || defined(_SVID_SOURCE) || defined(_POSIX_SOURCE)
+#if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 1) || defined(_XOPEN_SOURCE) || defined(_BSD_SOURCE) || defined(_SVID_SOURCE) || defined(_POSIX_SOURCE)
 inline std::tm localtime_s(const std::time_t* src)
 {
     std::tm dst;
@@ -35,7 +35,7 @@ inline std::tm gmtime_s(const std::time_t* src)
     if (!result) { throw std::runtime_error("gmtime_r failed."); }
     return dst;
 }
-#elif _MSC_VER
+#elif defined(_MSC_VER)
 inline std::tm localtime_s(const std::time_t* src)
 {
     std::tm dst;
@@ -172,9 +172,9 @@ template<typename charT, typename traits>
 std::basic_ostream<charT, traits>&
 operator<<(std::basic_ostream<charT, traits>& os, const local_date& date)
 {
-    os << std::setfill('0') << std::setw(4) << static_cast<int>(date.year     ) << '-';
-    os << std::setfill('0') << std::setw(2) << static_cast<int>(date.month + 1) << '-';
-    os << std::setfill('0') << std::setw(2) << static_cast<int>(date.day      );
+    os << std::setfill('0') << std::setw(4) << static_cast<int>(date.year )     << '-';
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(date.month) + 1 << '-';
+    os << std::setfill('0') << std::setw(2) << static_cast<int>(date.day  )    ;
     return os;
 }
 

toml/exception.hpp

@@ -12,7 +12,7 @@ namespace toml
 struct exception : public std::exception
 {
   public:
-    exception(const source_location& loc): loc_(loc) {}
+    explicit exception(const source_location& loc): loc_(loc) {}
     virtual ~exception() noexcept override = default;
     virtual const char* what() const noexcept override {return "";}
     virtual source_location const& location() const noexcept {return loc_;}

toml/get.hpp

@@ -259,6 +259,15 @@ template<typename T, typename C,
          std::size_t S = sizeof(::toml::from<T>)>
 T get(const basic_value<C, M, V>&);
 
+// T(const toml::value&) and T is not toml::basic_value
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<detail::is_basic_value<T>>,
+    std::is_constructible<T, const basic_value<C, M, V>&>
+    >::value, T>
+get(const basic_value<C, M, V>&);
+
 // ============================================================================
 // array-like types; most likely STL container, like std::vector, etc.
 
@@ -417,6 +426,17 @@ T get(const basic_value<C, M, V>& v)
     return ::toml::from<T>::from_toml(v);
 }
 
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::conjunction<
+    detail::negation<detail::is_basic_value<T>>,
+    std::is_constructible<T, const basic_value<C, M, V>&>
+    >::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    return T(v);
+}
+
 // ============================================================================
 // find
 
@@ -429,10 +449,7 @@ basic_value<C, M, V> const& find(const basic_value<C, M, V>& v, const key& ky)
     const auto& tab = v.as_table();
     if(tab.count(ky) == 0)
     {
-        throw std::out_of_range(detail::format_underline(concat_to_string(
-            "key \"", ky, "\" not found"), {
-                {std::addressof(detail::get_region(v)), "in this table"}
-            }));
+        detail::throw_key_not_found_error(v, ky);
     }
     return tab.at(ky);
 }
@@ -443,10 +460,7 @@ basic_value<C, M, V>& find(basic_value<C, M, V>& v, const key& ky)
     auto& tab = v.as_table();
     if(tab.count(ky) == 0)
     {
-        throw std::out_of_range(detail::format_underline(concat_to_string(
-            "key \"", ky, "\" not found"), {
-                {std::addressof(detail::get_region(v)), "in this table"}
-            }));
+        detail::throw_key_not_found_error(v, ky);
     }
     return tab.at(ky);
 }
@@ -457,14 +471,57 @@ basic_value<C, M, V> find(basic_value<C, M, V>&& v, const key& ky)
     typename basic_value<C, M, V>::table_type tab = std::move(v).as_table();
     if(tab.count(ky) == 0)
     {
-        throw std::out_of_range(detail::format_underline(concat_to_string(
-            "key \"", ky, "\" not found"), {
-                {std::addressof(detail::get_region(v)), "in this table"}
-            }));
+        detail::throw_key_not_found_error(v, ky);
     }
     return basic_value<C, M, V>(std::move(tab.at(ky)));
 }
 
+// ----------------------------------------------------------------------------
+// find(value, idx)
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> const&
+find(const basic_value<C, M, V>& v, const std::size_t idx)
+{
+    const auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {
+                {std::addressof(detail::get_region(v)), "in this array"}
+            }));
+    }
+    return ary.at(idx);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V>& find(basic_value<C, M, V>& v, const std::size_t idx)
+{
+    auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {
+                {std::addressof(detail::get_region(v)), "in this array"}
+            }));
+    }
+    return ary.at(idx);
+}
+template<typename C,
+         template<typename ...> class M, template<typename ...> class V>
+basic_value<C, M, V> find(basic_value<C, M, V>&& v, const std::size_t idx)
+{
+    auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {
+                {std::addressof(detail::get_region(v)), "in this array"}
+            }));
+    }
+    return basic_value<C, M, V>(std::move(ary.at(idx)));
+}
+
 // ----------------------------------------------------------------------------
 // find<T>(value, key);
 
@@ -476,10 +533,7 @@ find(const basic_value<C, M, V>& v, const key& ky)
     const auto& tab = v.as_table();
     if(tab.count(ky) == 0)
     {
-        throw std::out_of_range(detail::format_underline(concat_to_string(
-            "key \"", ky, "\" not found"), {
-                {std::addressof(detail::get_region(v)), "in this table"}
-            }));
+        detail::throw_key_not_found_error(v, ky);
     }
     return ::toml::get<T>(tab.at(ky));
 }
@@ -492,10 +546,7 @@ find(basic_value<C, M, V>& v, const key& ky)
     auto& tab = v.as_table();
     if(tab.count(ky) == 0)
     {
-        throw std::out_of_range(detail::format_underline(concat_to_string(
-            "key \"", ky, "\" not found"), {
-                {std::addressof(detail::get_region(v)), "in this table"}
-            }));
+        detail::throw_key_not_found_error(v, ky);
     }
     return ::toml::get<T>(tab.at(ky));
 }
@@ -508,65 +559,157 @@ find(basic_value<C, M, V>&& v, const key& ky)
     typename basic_value<C, M, V>::table_type tab = std::move(v).as_table();
     if(tab.count(ky) == 0)
     {
-        throw std::out_of_range(detail::format_underline(concat_to_string(
-            "key \"", ky, "\" not found"), {
-                {std::addressof(detail::get_region(v)), "in this table"}
-            }));
+        detail::throw_key_not_found_error(v, ky);
     }
     return ::toml::get<T>(std::move(tab.at(ky)));
 }
 
+// ----------------------------------------------------------------------------
+// find<T>(value, idx)
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V> const&>()))
+find(const basic_value<C, M, V>& v, const std::size_t idx)
+{
+    const auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {
+                {std::addressof(detail::get_region(v)), "in this array"}
+            }));
+    }
+    return ::toml::get<T>(ary.at(idx));
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&>()))
+find(basic_value<C, M, V>& v, const std::size_t idx)
+{
+    auto& ary = v.as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {
+                {std::addressof(detail::get_region(v)), "in this array"}
+            }));
+    }
+    return ::toml::get<T>(ary.at(idx));
+}
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&&>()))
+find(basic_value<C, M, V>&& v, const std::size_t idx)
+{
+    typename basic_value<C, M, V>::array_type ary = std::move(v).as_array();
+    if(ary.size() <= idx)
+    {
+        throw std::out_of_range(detail::format_underline(concat_to_string(
+            "index ", idx, " is out of range"), {
+                {std::addressof(detail::get_region(v)), "in this array"}
+            }));
+    }
+    return ::toml::get<T>(std::move(ary.at(idx)));
+}
+
 // --------------------------------------------------------------------------
 // toml::find(toml::value, toml::key, Ts&& ... keys)
 
+namespace detail
+{
+// It suppresses warnings by -Wsign-conversion. Let's say we have the following
+// code.
+// ```cpp
+// const auto x = toml::find<std::string>(data, "array", 0);
+// ```
+// Here, the type of literal number `0` is `int`. `int` is a signed integer.
+// `toml::find` takes `std::size_t` as an index. So it causes implicit sign
+// conversion and `-Wsign-conversion` warns about it. Using `0u` instead of `0`
+// suppresses the warning, but it makes user code messy.
+//     To suppress this warning, we need to be aware of type conversion caused
+// by `toml::find(v, key1, key2, ... keys)`. But the thing is that the types of
+// keys can be any combination of {string-like, size_t-like}. Of course we can't
+// write down all the combinations. Thus we need to use some function that
+// recognize the type of argument and cast it into `std::string` or
+// `std::size_t` depending on the context.
+//     `key_cast` does the job. It has 2 overloads. One is invoked when the
+// argument type is an integer and cast the argument into `std::size_t`. The
+// other is invoked when the argument type is not an integer, possibly one of
+// std::string, const char[N] or const char*, and construct std::string from
+// the argument.
+//     `toml::find(v, k1, k2, ... ks)` uses `key_cast` before passing `ks` to
+// `toml::find(v, k)` to suppress -Wsign-conversion.
+
+template<typename T>
+enable_if_t<conjunction<std::is_integral<remove_cvref_t<T>>,
+            negation<std::is_same<remove_cvref_t<T>, bool>>>::value, std::size_t>
+key_cast(T&& v) noexcept
+{
+    return std::size_t(v);
+}
+template<typename T>
+enable_if_t<negation<conjunction<std::is_integral<remove_cvref_t<T>>,
+            negation<std::is_same<remove_cvref_t<T>, bool>>>>::value, std::string>
+key_cast(T&& v) noexcept
+{
+    return std::string(std::forward<T>(v));
+}
+} // detail
+
 template<typename C,
          template<typename ...> class M, template<typename ...> class V,
-         typename ... Ts>
+         typename Key1, typename Key2, typename ... Keys>
 const basic_value<C, M, V>&
-find(const basic_value<C, M, V>& v, const ::toml::key& ky, Ts&& ... keys)
+find(const basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
 {
-    return ::toml::find(::toml::find(v, ky), std::forward<Ts>(keys)...);
+    return ::toml::find(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
 }
 template<typename C,
          template<typename ...> class M, template<typename ...> class V,
-         typename ... Ts>
+         typename Key1, typename Key2, typename ... Keys>
 basic_value<C, M, V>&
-find(basic_value<C, M, V>& v, const ::toml::key& ky, Ts&& ... keys)
+find(basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
 {
-    return ::toml::find(::toml::find(v, ky), std::forward<Ts>(keys)...);
+    return ::toml::find(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
 }
 template<typename C,
          template<typename ...> class M, template<typename ...> class V,
-         typename ... Ts>
+         typename Key1, typename Key2, typename ... Keys>
 basic_value<C, M, V>
-find(basic_value<C, M, V>&& v, const ::toml::key& ky, Ts&& ... keys)
+find(basic_value<C, M, V>&& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
 {
-    return ::toml::find(::toml::find(std::move(v), ky), std::forward<Ts>(keys)...);
+    return ::toml::find(::toml::find(std::move(v), std::forward<Key1>(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
 }
 
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V,
-         typename ... Ts>
+         typename Key1, typename Key2, typename ... Keys>
 decltype(::toml::get<T>(std::declval<const basic_value<C, M, V>&>()))
-find(const basic_value<C, M, V>& v, const ::toml::key& ky, Ts&& ... keys)
+find(const basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
 {
-    return ::toml::find<T>(::toml::find(v, ky), std::forward<Ts>(keys)...);
+    return ::toml::find<T>(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
 }
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V,
-         typename ... Ts>
+         typename Key1, typename Key2, typename ... Keys>
 decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&>()))
-find(basic_value<C, M, V>& v, const ::toml::key& ky, Ts&& ... keys)
+find(basic_value<C, M, V>& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
 {
-    return ::toml::find<T>(::toml::find(v, ky), std::forward<Ts>(keys)...);
+    return ::toml::find<T>(::toml::find(v, detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
 }
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V,
-         typename ... Ts>
+         typename Key1, typename Key2, typename ... Keys>
 decltype(::toml::get<T>(std::declval<basic_value<C, M, V>&&>()))
-find(basic_value<C, M, V>&& v, const ::toml::key& ky, Ts&& ... keys)
+find(basic_value<C, M, V>&& v, Key1&& k1, Key2&& k2, Keys&& ... keys)
 {
-    return ::toml::find<T>(::toml::find(std::move(v), ky), std::forward<Ts>(keys)...);
+    return ::toml::find<T>(::toml::find(std::move(v), detail::key_cast(k1)),
+            detail::key_cast(k2), std::forward<Keys>(keys)...);
 }
 
 // ============================================================================

toml/lexer.hpp

@@ -154,12 +154,53 @@ using lex_basic_string = sequence<lex_quotation_mark,
                                   repeat<lex_basic_char, unlimited>,
                                   lex_quotation_mark>;
 
+// After toml post-v0.5.0, it is explicitly clarified how quotes in ml-strings
+// are allowed to be used.
+// After this, the following strings are *explicitly* allowed.
+// - One or two `"`s in a multi-line basic string is allowed wherever it is.
+// - Three consecutive `"`s in a multi-line basic string is considered as a delimiter.
+// - One or two `"`s can appear just before or after the delimiter.
+// ```toml
+// str4 = """Here are two quotation marks: "". Simple enough."""
+// str5 = """Here are three quotation marks: ""\"."""
+// str6 = """Here are fifteen quotation marks: ""\"""\"""\"""\"""\"."""
+// str7 = """"This," she said, "is just a pointless statement.""""
+// ```
+// In the current implementation (v3.3.0), it is difficult to parse `str7` in
+// the above example. It is difficult to recognize `"` at the end of string body
+// collectly. It will be misunderstood as a `"""` delimiter and an additional,
+// invalid `"`. Like this:
+// ```console
+//   what():  [error] toml::parse_table: invalid line format
+//  --> hoge.toml
+//     |
+//  13 | str7 = """"This," she said, "is just a pointless statement.""""
+//     |                                                               ^- expected newline, but got '"'.
+// ```
+// As a quick workaround for this problem, `lex_ml_basic_string_delim` was
+// splitted into two, `lex_ml_basic_string_open` and `lex_ml_basic_string_close`.
+// `lex_ml_basic_string_open` allows only `"""`. `_close` allows 3-5 `"`s.
+// In parse_ml_basic_string() function, the trailing `"`s will be attached to
+// the string body.
+//
+// Note: This feature is a "clarification". Therefore this change is considered
+//       as a spec that has been defined since the time when the multi-line
+//       basic string was introduced. Although it is a post-v0.5.0 changes,
+//       this change will be activated regardless of the flag,
+//       `TOML11_USE_UNRELEASED_TOML_FEATURES`.
+//
 using lex_ml_basic_string_delim = repeat<lex_quotation_mark, exactly<3>>;
+using lex_ml_basic_string_open  = lex_ml_basic_string_delim;
+using lex_ml_basic_string_close = sequence<
+        repeat<lex_quotation_mark, exactly<3>>,
+        maybe<lex_quotation_mark>, maybe<lex_quotation_mark>
+    >;
+
 #ifdef TOML11_USE_UNRELEASED_TOML_FEATURES
 using lex_ml_basic_unescaped    = exclude<either<in_range<0x00, 0x08>, // 0x09
                                                  in_range<0x0a, 0x1F>, // is tab
-                                                 character<0x5C>,
-                                                 character<0x7F>,
+                                                 character<0x5C>, // backslash
+                                                 character<0x7F>, // DEL
                                                  lex_ml_basic_string_delim>>;
 #else // TOML v0.5.0
 using lex_ml_basic_unescaped    = exclude<either<in_range<0x00,0x1F>,
@@ -176,9 +217,9 @@ using lex_ml_basic_char = either<lex_ml_basic_unescaped, lex_escaped>;
 using lex_ml_basic_body = repeat<either<lex_ml_basic_char, lex_newline,
                                         lex_ml_basic_escaped_newline>,
                                  unlimited>;
-using lex_ml_basic_string = sequence<lex_ml_basic_string_delim,
+using lex_ml_basic_string = sequence<lex_ml_basic_string_open,
                                      lex_ml_basic_body,
-                                     lex_ml_basic_string_delim>;
+                                     lex_ml_basic_string_close>;
 
 using lex_literal_char = exclude<either<in_range<0x00, 0x08>,
                                         in_range<0x10, 0x19>, character<0x27>>>;
@@ -187,7 +228,13 @@ using lex_literal_string = sequence<lex_apostrophe,
                                     repeat<lex_literal_char, unlimited>,
                                     lex_apostrophe>;
 
+// the same reason as above.
 using lex_ml_literal_string_delim = repeat<lex_apostrophe, exactly<3>>;
+using lex_ml_literal_string_open  = lex_ml_literal_string_delim;
+using lex_ml_literal_string_close = sequence<
+        repeat<lex_apostrophe, exactly<3>>,
+        maybe<lex_apostrophe>, maybe<lex_apostrophe>
+    >;
 
 using lex_ml_literal_char = exclude<either<in_range<0x00, 0x08>,
                                            in_range<0x10, 0x1F>,
@@ -195,9 +242,9 @@ using lex_ml_literal_char = exclude<either<in_range<0x00, 0x08>,
                                            lex_ml_literal_string_delim>>;
 using lex_ml_literal_body = repeat<either<lex_ml_literal_char, lex_newline>,
                                    unlimited>;
-using lex_ml_literal_string = sequence<lex_ml_literal_string_delim,
+using lex_ml_literal_string = sequence<lex_ml_literal_string_open,
                                        lex_ml_literal_body,
-                                       lex_ml_literal_string_delim>;
+                                       lex_ml_literal_string_close>;
 
 using lex_string = either<lex_ml_basic_string,   lex_basic_string,
                           lex_ml_literal_string, lex_literal_string>;

toml/parser.hpp

@@ -256,7 +256,7 @@ std::string read_utf8_codepoint(const region<Container>& reg,
     std::istringstream iss(str);
     iss >> std::hex >> codepoint;
 
-    const auto to_char = [](const int i) noexcept -> char {
+    const auto to_char = [](const std::uint_least32_t i) noexcept -> char {
         const auto uc = static_cast<unsigned char>(i);
         return *reinterpret_cast<const char*>(std::addressof(uc));
     };
@@ -375,7 +375,7 @@ parse_ml_basic_string(location<Container>& loc)
         std::string retval;
         retval.reserve(token.unwrap().size());
 
-        auto delim = lex_ml_basic_string_delim::invoke(inner_loc);
+        auto delim = lex_ml_basic_string_open::invoke(inner_loc);
         if(!delim)
         {
             throw internal_error(format_underline(
@@ -410,7 +410,26 @@ parse_ml_basic_string(location<Container>& loc)
                     {{std::addressof(inner_loc), "not sufficient token"}}),
                     source_location(std::addressof(inner_loc)));
             }
-            delim = lex_ml_basic_string_delim::invoke(inner_loc);
+            delim = lex_ml_basic_string_close::invoke(inner_loc);
+        }
+        // `lex_ml_basic_string_close` allows 3 to 5 `"`s to allow 1 or 2 `"`s
+        // at just before the delimiter. Here, we need to attach `"`s at the
+        // end of the string body, if it exists.
+        // For detail, see the definition of `lex_ml_basic_string_close`.
+        assert(std::all_of(delim.unwrap().first(), delim.unwrap().last(),
+                           [](const char c) noexcept {return c == '\"';}));
+        switch(delim.unwrap().size())
+        {
+            case 3: {break;}
+            case 4: {retval += "\"";  break;}
+            case 5: {retval += "\"\""; break;}
+            default:
+            {
+                throw internal_error(format_underline(
+                    "parse_ml_basic_string: closing delimiter has invalid length",
+                    {{std::addressof(inner_loc), "end of this"}}),
+                    source_location(std::addressof(inner_loc)));
+            }
         }
         return ok(std::make_pair(toml::string(retval), token.unwrap()));
     }
@@ -485,7 +504,7 @@ parse_ml_literal_string(location<Container>& loc)
     {
         location<std::string> inner_loc(loc.name(), token.unwrap().str());
 
-        const auto open = lex_ml_literal_string_delim::invoke(inner_loc);
+        const auto open = lex_ml_literal_string_open::invoke(inner_loc);
         if(!open)
         {
             throw internal_error(format_underline(
@@ -498,7 +517,7 @@ parse_ml_literal_string(location<Container>& loc)
 
         const auto body = lex_ml_literal_body::invoke(inner_loc);
 
-        const auto close = lex_ml_literal_string_delim::invoke(inner_loc);
+        const auto close = lex_ml_literal_string_close::invoke(inner_loc);
         if(!close)
         {
             throw internal_error(format_underline(
@@ -506,9 +525,29 @@ parse_ml_literal_string(location<Container>& loc)
                 {{std::addressof(inner_loc), "should be '''"}}),
                 source_location(std::addressof(inner_loc)));
         }
-        return ok(std::make_pair(
-                  toml::string(body.unwrap().str(), toml::string_t::literal),
-                  token.unwrap()));
+        // `lex_ml_literal_string_close` allows 3 to 5 `'`s to allow 1 or 2 `'`s
+        // at just before the delimiter. Here, we need to attach `'`s at the
+        // end of the string body, if it exists.
+        // For detail, see the definition of `lex_ml_basic_string_close`.
+
+        std::string retval = body.unwrap().str();
+        assert(std::all_of(close.unwrap().first(), close.unwrap().last(),
+                           [](const char c) noexcept {return c == '\'';}));
+        switch(close.unwrap().size())
+        {
+            case 3: {break;}
+            case 4: {retval += "'";  break;}
+            case 5: {retval += "''"; break;}
+            default:
+            {
+                throw internal_error(format_underline(
+                    "parse_ml_literal_string: closing delimiter has invalid length",
+                    {{std::addressof(inner_loc), "end of this"}}),
+                    source_location(std::addressof(inner_loc)));
+            }
+        }
+        return ok(std::make_pair(toml::string(retval, toml::string_t::literal),
+                                 token.unwrap()));
     }
     else
     {
@@ -792,13 +831,13 @@ parse_offset_datetime(location<Container>& loc)
             const auto str = ofs.unwrap().str();
             if(str.front() == '+')
             {
-                offset.hour   = static_cast<std::int8_t>(from_string<int>(str.substr(1,2), 0));
-                offset.minute = static_cast<std::int8_t>(from_string<int>(str.substr(4,2), 0));
+                offset = time_offset(from_string<int>(str.substr(1,2), 0),
+                                     from_string<int>(str.substr(4,2), 0));
             }
             else
             {
-                offset.hour   = -static_cast<std::int8_t>(from_string<int>(str.substr(1,2), 0));
-                offset.minute = -static_cast<std::int8_t>(from_string<int>(str.substr(4,2), 0));
+                offset = time_offset(-from_string<int>(str.substr(1,2), 0),
+                                     -from_string<int>(str.substr(4,2), 0));
             }
         }
         else if(*inner_loc.iter() != 'Z' && *inner_loc.iter() != 'z')

toml/region.hpp

@@ -55,7 +55,7 @@ struct region_base
     // number of characters in the line after the region
     virtual std::size_t after()    const noexcept {return 0;}
 
-    virtual std::vector<std::string> comments()const {return {};}
+    virtual std::vector<std::string> comments() const {return {};}
     // ```toml
     // # comment_before
     // key = "value" # comment_inline
@@ -511,7 +511,7 @@ inline std::string format_underline(const std::string& message,
         retval << '\n';
         retval << make_string(static_cast<std::size_t>(line_num_width + 1), ' ');
         retval << color::bold << color::blue << " | " << color::reset;
-        for(const auto help : helps)
+        for(const auto& help : helps)
         {
             retval << color::bold << "\nHint: " << color::reset;
             retval << help;

toml/serializer.hpp

@@ -22,39 +22,62 @@ namespace toml
 // Since toml restricts characters available in a bare key, generally a string
 // should be escaped. But checking whether a string needs to be surrounded by
 // a `"` and escaping some special character is boring.
-inline std::string format_key(const toml::key& key)
+template<typename charT, typename traits, typename Alloc>
+std::basic_string<charT, traits, Alloc>
+format_key(const std::basic_string<charT, traits, Alloc>& key)
 {
+    // check the key can be a bare (unquoted) key
     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("\"");
+
+    //if it includes special characters, then format it in a "quoted" key.
+    std::basic_string<charT, traits, Alloc> serialized("\"");
     for(const char c : key)
     {
         switch(c)
         {
-            case '\\': {token += "\\\\"; break;}
-            case '\"': {token += "\\\""; break;}
-            case '\b': {token += "\\b";  break;}
-            case '\t': {token += "\\t";  break;}
-            case '\f': {token += "\\f";  break;}
-            case '\n': {token += "\\n";  break;}
-            case '\r': {token += "\\r";  break;}
-            default  : {token += c;      break;}
+            case '\\': {serialized += "\\\\"; break;}
+            case '\"': {serialized += "\\\""; break;}
+            case '\b': {serialized += "\\b";  break;}
+            case '\t': {serialized += "\\t";  break;}
+            case '\f': {serialized += "\\f";  break;}
+            case '\n': {serialized += "\\n";  break;}
+            case '\r': {serialized += "\\r";  break;}
+            default  : {serialized += c;      break;}
         }
     }
-    token += "\"";
-    return token;
+    serialized += "\"";
+    return serialized;
 }
 
-template<typename Comment,
-         template<typename ...> class Table,
-         template<typename ...> class Array>
+template<typename charT, typename traits, typename Alloc>
+std::basic_string<charT, traits, Alloc>
+format_keys(const std::vector<std::basic_string<charT, traits, Alloc>>& keys)
+{
+    std::basic_string<charT, traits, Alloc> serialized;
+    if(keys.empty()) {return serialized;}
+
+    for(const auto& ky : keys)
+    {
+        serialized += format_key(ky);
+        serialized += charT('.');
+    }
+    serialized.pop_back(); // remove the last dot '.'
+    return serialized;
+}
+
+template<typename Value>
 struct serializer
 {
-    using value_type           = basic_value<Comment, Table, Array>;
+    static_assert(detail::is_basic_value<Value>::value,
+                  "toml::serializer is for toml::value and its variants, "
+                  "toml::basic_value<...>.");
+
+    using value_type           = Value;
     using key_type             = typename value_type::key_type            ;
     using comment_type         = typename value_type::comment_type        ;
     using boolean_type         = typename value_type::boolean_type        ;
@@ -119,12 +142,17 @@ struct serializer
             return token; // there is no exponent part. just return it.
         }
 #ifdef TOML11_USE_UNRELEASED_TOML_FEATURES
-        // Although currently it is not released yet, TOML will allow
-        // zero-prefix in an exponent part such as 1.234e+01.
-        // The following code removes the zero prefixes.
-        // If the feature is activated, the following codes can be skipped.
+        // Although currently it is not released yet as a tagged version,
+        // TOML will allow zero-prefix in an exponent part, such as `1.234e+01`.
+        // ```toml
+        // num1 = 1.234e+1  # OK in TOML v0.5.0
+        // num2 = 1.234e+01 # error in TOML v0.5.0 but will be allowed soon
+        // ```
+        // To avoid `e+01`, the following `else` section removes the zero
+        // prefixes in the exponent part.
+        // If the feature is activated, it can be skipped.
         return token;
-#endif
+#else
         // zero-prefix in an exponent is NOT allowed in TOML v0.5.0.
         // remove it if it exists.
         bool        sign_exists = false;
@@ -143,17 +171,29 @@ struct serializer
                         zero_prefix);
         }
         return token;
+#endif
     }
     std::string operator()(const string_type& s) const
     {
         if(s.kind == string_t::basic)
         {
-            if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend())
+            if(std::find(s.str.cbegin(), s.str.cend(), '\n') != s.str.cend() ||
+               std::find(s.str.cbegin(), s.str.cend(), '\"') != 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;
+                // if linefeed or double-quote is contained,
+                // make it multiline basic string.
+                const auto escaped = this->escape_ml_basic_string(s.str);
+                std::string open("\"\"\"");
+                std::string close("\"\"\"");
+                if(escaped.find('\n') != std::string::npos ||
+                   this->width_ < escaped.size() + 6)
+                {
+                    // if the string body contains newline or is enough long,
+                    // add newlines after and before delimiters.
+                    open += "\n";
+                    close = std::string("\\\n") + close;
+                }
+                return open + escaped + close;
             }
 
             // no linefeed. try to make it oneline-string.
@@ -194,7 +234,11 @@ struct serializer
             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");
+                std::string open("'''");
+                if(this->width_ + 6 < s.str.size())
+                {
+                    open += '\n'; // the first newline is ignored by TOML spec
+                }
                 const std::string close("'''");
                 return open + s.str + close;
             }
@@ -249,7 +293,7 @@ struct serializer
                 std::string token;
                 if(!keys_.empty())
                 {
-                    token += this->serialize_key(keys_.back());
+                    token += format_key(keys_.back());
                     token += " = ";
                 }
                 bool failed = false;
@@ -305,7 +349,7 @@ struct serializer
                     }
                 }
                 token += "[[";
-                token += this->serialize_dotted_key(keys_);
+                token += format_keys(keys_);
                 token += "]]\n";
                 token += this->make_multiline_table(item.as_table());
             }
@@ -417,7 +461,7 @@ struct serializer
             std::string token;
             if(!this->keys_.empty())
             {
-                token += this->serialize_key(this->keys_.back());
+                token += format_key(this->keys_.back());
                 token += " = ";
             }
             token += this->make_inline_table(v);
@@ -432,7 +476,7 @@ struct serializer
         if(!keys_.empty())
         {
             token += '[';
-            token += this->serialize_dotted_key(keys_);
+            token += format_keys(keys_);
             token += "]\n";
         }
         token += this->make_multiline_table(v);
@@ -441,25 +485,6 @@ struct serializer
 
   private:
 
-    std::string serialize_key(const toml::key& key) const
-    {
-        return ::toml::format_key(key);
-    }
-
-    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.
@@ -489,7 +514,9 @@ struct serializer
             switch(*i)
             {
                 case '\\': {retval += "\\\\"; break;}
-                case '\"': {retval += "\\\""; break;}
+                // One or two consecutive "s are allowed.
+                // Later we will check there are no three consecutive "s.
+                //   case '\"': {retval += "\\\""; break;}
                 case '\b': {retval += "\\b";  break;}
                 case '\t': {retval += "\\t";  break;}
                 case '\f': {retval += "\\f";  break;}
@@ -510,6 +537,23 @@ struct serializer
                 default: {retval += *i; break;}
             }
         }
+        // Only 1 or 2 consecutive `"`s are allowed in multiline basic string.
+        // 3 consecutive `"`s are considered as a closing delimiter.
+        // We need to check if there are 3 or more consecutive `"`s and insert
+        // backslash to break them down into several short `"`s like the `str6`
+        // in the following example.
+        // ```toml
+        // str4 = """Here are two quotation marks: "". Simple enough."""
+        // # str5 = """Here are three quotation marks: """."""  # INVALID
+        // str5 = """Here are three quotation marks: ""\"."""
+        // str6 = """Here are fifteen quotation marks: ""\"""\"""\"""\"""\"."""
+        // ```
+        auto found_3_quotes = retval.find("\"\"\"");
+        while(found_3_quotes != std::string::npos)
+        {
+            retval.replace(found_3_quotes, 3, "\"\"\\\"");
+            found_3_quotes = retval.find("\"\"\"");
+        }
         return retval;
     }
 
@@ -564,7 +608,7 @@ struct serializer
         {
             // 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 += format_key(kv.first);
             token += '=';
             token += visit(serializer(std::numeric_limits<std::size_t>::max(),
                                       this->float_prec_, true), kv.second);
@@ -579,7 +623,7 @@ struct serializer
 
         // 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)
+        for(const auto& kv : v)
         {
             if(kv.second.is_table() || is_array_of_tables(kv.second))
             {
@@ -595,7 +639,7 @@ struct serializer
                     token += '\n';
                 }
             }
-            const auto key_and_sep    = this->serialize_key(kv.first) + " = ";
+            const auto key_and_sep    = format_key(kv.first) + " = ";
             const auto residual_width = (this->width_ > key_and_sep.size()) ?
                                         this->width_ - key_and_sep.size() : 0;
             token += key_and_sep;
@@ -677,6 +721,7 @@ format(const basic_value<C, M, V>& v, std::size_t w = 80u,
        int fprec = std::numeric_limits<toml::floating>::max_digits10,
        bool no_comment = false, bool force_inline = false)
 {
+    using value_type = basic_value<C, M, V>;
     // if value is a table, it is considered to be a root object.
     // the root object can't be an inline table.
     if(v.is_table())
@@ -687,10 +732,10 @@ format(const basic_value<C, M, V>& v, std::size_t w = 80u,
             oss << v.comments();
             oss << '\n'; // to split the file comment from the first element
         }
-        oss << visit(serializer<C, M, V>(w, fprec, no_comment, false), v);
+        oss << visit(serializer<value_type>(w, fprec, no_comment, false), v);
         return oss.str();
     }
-    return visit(serializer<C, M, V>(w, fprec, force_inline), v);
+    return visit(serializer<value_type>(w, fprec, force_inline), v);
 }
 
 namespace detail
@@ -726,6 +771,8 @@ template<typename charT, typename traits, typename C,
 std::basic_ostream<charT, traits>&
 operator<<(std::basic_ostream<charT, traits>& os, const basic_value<C, M, V>& v)
 {
+    using value_type = basic_value<C, M, V>;
+
     // get status of std::setw().
     const auto w     = static_cast<std::size_t>(os.width());
     const int  fprec = static_cast<int>(os.precision());
@@ -741,7 +788,7 @@ operator<<(std::basic_ostream<charT, traits>& os, const basic_value<C, M, V>& v)
         os << '\n'; // to split the file comment from the first element
     }
     // the root object can't be an inline table. so pass `false`.
-    os << visit(serializer<C, M, V>(w, fprec, false, no_comment), v);
+    os << visit(serializer<value_type>(w, fprec, false, no_comment), v);
 
     // if v is a non-table value, and has only one comment, then
     // put a comment just after a value. in the following way.

toml/storage.hpp

@@ -16,10 +16,9 @@ struct storage
 {
     using value_type = T;
 
-    storage(value_type const& v): ptr(toml::make_unique<T>(v)) {}
-    storage(value_type&&      v): ptr(toml::make_unique<T>(std::move(v))) {}
+    explicit storage(value_type const& v): ptr(toml::make_unique<T>(v)) {}
+    explicit storage(value_type&&      v): ptr(toml::make_unique<T>(std::move(v))) {}
     ~storage() = default;
-
     storage(const storage& rhs): ptr(toml::make_unique<T>(*rhs.ptr)) {}
     storage& operator=(const storage& rhs)
     {

toml/traits.hpp

@@ -111,6 +111,14 @@ struct has_into_toml_method
 // ---------------------------------------------------------------------------
 // C++17 and/or/not
 
+#if __cplusplus >= 201703L
+
+using std::conjunction;
+using std::disjunction;
+using std::negation;
+
+#else
+
 template<typename ...> struct conjunction : std::true_type{};
 template<typename T>   struct conjunction<T> : T{};
 template<typename T, typename ... Ts>
@@ -128,6 +136,8 @@ struct disjunction<T, Ts...> :
 template<typename T>
 struct negation : std::integral_constant<bool, !static_cast<bool>(T::value)>{};
 
+#endif
+
 // ---------------------------------------------------------------------------
 // type checkers
 
@@ -182,6 +192,13 @@ struct is_basic_value<::toml::basic_value<C, M, V>>: std::true_type{};
 // ---------------------------------------------------------------------------
 // C++14 index_sequence
 
+#if __cplusplus >= 201402L
+
+using std::index_sequence;
+using std::make_index_sequence;
+
+#else
+
 template<std::size_t ... Ns> struct index_sequence{};
 
 template<typename IS, std::size_t N> struct push_back_index_sequence{};
@@ -205,11 +222,22 @@ struct index_sequence_maker<0>
 template<std::size_t N>
 using make_index_sequence = typename index_sequence_maker<N-1>::type;
 
+#endif // __cplusplus >= 2014
+
 // ---------------------------------------------------------------------------
 // C++14 enable_if_t
+
+#if __cplusplus >= 201402L
+
+using std::enable_if_t;
+
+#else
+
 template<bool B, typename T>
 using enable_if_t = typename std::enable_if<B, T>::type;
 
+#endif // __cplusplus >= 2014
+
 // ---------------------------------------------------------------------------
 // return_type_of_t
 

toml/utility.hpp

@@ -20,12 +20,20 @@
 namespace toml
 {
 
+#if __cplusplus >= 201402L
+
+using std::make_unique;
+
+#else
+
 template<typename T, typename ... Ts>
 inline std::unique_ptr<T> make_unique(Ts&& ... args)
 {
     return std::unique_ptr<T>(new T(std::forward<Ts>(args)...));
 }
 
+#endif // __cplusplus >= 2014
+
 namespace detail
 {
 
@@ -76,10 +84,10 @@ std::string concat_to_string(Ts&& ... args)
     return detail::concat_to_string_impl(oss, std::forward<Ts>(args) ...);
 }
 
-template<typename T, typename U>
-T from_string(const std::string& str, U&& opt)
+template<typename T>
+T from_string(const std::string& str, T opt)
 {
-    T v(static_cast<T>(std::forward<U>(opt)));
+    T v(opt);
     std::istringstream iss(str);
     iss >> v;
     return v;