Merge pull request #20 from ToruNiina/format-error

add an extra parameter `hints` to format_error

tests/test_parse_file.cpp

@@ -194,3 +194,469 @@ BOOST_AUTO_TEST_CASE(test_hard_example)
     BOOST_CHECK(toml::get<std::vector<std::string>>(bit.at("multi_line_array")) ==
                 expected_multi_line_array);
 }
+
+// ---------------------------------------------------------------------------
+// after here, the test codes generate the content of a file.
+
+BOOST_AUTO_TEST_CASE(test_file_with_BOM)
+{
+    {
+        const std::string table(
+            "\xEF\xBB\xBF" // BOM
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss, "test_file_with_BOM.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "\xEF\xBB\xBF" // BOM
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss, "test_file_with_BOM_CRLF.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}
+
+BOOST_AUTO_TEST_CASE(test_file_without_newline_at_the_end_of_file)
+{
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\""
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\""
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_CRLF.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\" # comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\" # comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\" \t"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_ws.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\" \t"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_file_without_newline_at_the_end_of_file_ws.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}
+
+
+BOOST_AUTO_TEST_CASE(test_files_end_with_comment)
+{
+    // comment w/o newline
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment\n"
+            "# one more comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // comment w/ newline
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "# comment\n"
+            "# one more comment\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // CRLF version
+
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment\r\n"
+            "# one more comment"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "# comment\r\n"
+            "# one more comment\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_comment.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}
+
+
+BOOST_AUTO_TEST_CASE(test_files_end_with_empty_lines)
+{
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "\n"
+            "\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // with whitespaces
+
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  \n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  \n"
+            "  \n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "\n"
+            "  \n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  \n"
+            "\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // with whitespaces but no newline
+    {
+        const std::string table(
+            "key = \"value\"\n"
+            "[table]\n"
+            "key = \"value\"\n"
+            "  "
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+
+    // CRLF
+
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "\r\n"
+            "\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+
+    // with whitespaces
+
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  \r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "\r\n"
+            "  \r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  \r\n"
+            "\r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  \r\n"
+            "  \r\n"
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+    {
+        const std::string table(
+            "key = \"value\"\r\n"
+            "[table]\r\n"
+            "key = \"value\"\r\n"
+            "  "
+            );
+        std::istringstream iss(table);
+        const auto data = toml::parse(iss,
+                "test_files_end_with_newline.toml");
+
+        BOOST_CHECK_EQUAL(toml::get <std::string>(data.at("key")), "value");
+        BOOST_CHECK_EQUAL(toml::find<std::string>(data.at("table"), "key"), "value");
+    }
+}

toml/get.hpp

@@ -295,7 +295,7 @@ T get(const toml::value& v)
 // ============================================================================
 // find and get
 
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<const ::toml::value&>()))
 find(const toml::table& tab, const toml::key& ky,
      std::string tablename = "unknown table")
@@ -307,7 +307,7 @@ find(const toml::table& tab, const toml::key& ky,
     }
     return ::toml::get<T>(tab.at(ky));
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&>()))
 find(toml::table& tab, const toml::key& ky,
      std::string tablename = "unknown table")
@@ -319,7 +319,7 @@ find(toml::table& tab, const toml::key& ky,
     }
     return ::toml::get<T>(tab[ky]);
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&&>()))
 find(toml::table&& tab, const toml::key& ky,
      std::string tablename = "unknown table")
@@ -332,7 +332,7 @@ find(toml::table&& tab, const toml::key& ky,
     return ::toml::get<T>(std::move(tab[ky]));
 }
 
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<const ::toml::value&>()))
 find(const toml::value& v, const toml::key& ky)
 {
@@ -345,7 +345,7 @@ find(const toml::value& v, const toml::key& ky)
     }
     return ::toml::get<T>(tab.at(ky));
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&>()))
 find(toml::value& v, const toml::key& ky)
 {
@@ -358,7 +358,7 @@ find(toml::value& v, const toml::key& ky)
     }
     return ::toml::get<T>(tab.at(ky));
 }
-template<typename T>
+template<typename T = ::toml::value>
 decltype(::toml::get<T>(std::declval<::toml::value&&>()))
 find(toml::value&& v, const toml::key& ky)
 {

toml/parser.hpp

@@ -34,8 +34,8 @@ parse_boolean(location<Container>& loc)
         }
     }
     loc.iter() = first; //rollback
-    return err(format_underline("[error] toml::parse_boolean", loc,
-            "token is not boolean", {"boolean is `true` or `false`"}));
+    return err(std::string("[error] toml::parse_boolean: "
+                           "the next token is not a boolean"));
 }
 
 template<typename Container>
@@ -63,8 +63,8 @@ parse_binary_integer(location<Container>& loc)
         return ok(std::make_pair(retval, token.unwrap()));
     }
     loc.iter() = first;
-    return err(format_underline("[error] toml::parse_binary_integer", loc,
-            "token is not binary integer", {"binary integer is like: 0b0011"}));
+    return err(std::string("[error] toml::parse_binary_integer:"
+                           "the next token is not an integer"));
 }
 
 template<typename Container>
@@ -84,9 +84,8 @@ parse_octal_integer(location<Container>& loc)
         return ok(std::make_pair(retval, token.unwrap()));
     }
     loc.iter() = first;
-
-    return err(format_underline("[error] toml::parse_octal_integer", loc,
-            "token is not octal integer", {"octal integer is like: 0o775"}));
+    return err(std::string("[error] toml::parse_octal_integer:"
+                           "the next token is not an integer"));
 }
 
 template<typename Container>
@@ -106,8 +105,8 @@ parse_hexadecimal_integer(location<Container>& loc)
         return ok(std::make_pair(retval, token.unwrap()));
     }
     loc.iter() = first;
-    return err(format_underline("[error] toml::parse_hexadecimal_integer", loc,
-            "token is not hex integer", {"hex integer is like: 0xC0FFEE"}));
+    return err(std::string("[error] toml::parse_hexadecimal_integer"
+                           "the next token is not an integer"));
 }
 
 template<typename Container>
@@ -134,10 +133,8 @@ parse_integer(location<Container>& loc)
         return ok(std::make_pair(retval, token.unwrap()));
     }
     loc.iter() = first;
-    return err(format_underline("[error] toml::parse_integer", loc,
-            "token is not integer", {"integer is like: +42",
-            "hex integer is like: 0xC0FFEE", "octal integer is like: 0o775",
-            "binary integer is like: 0b0011"}));
+    return err(std::string("[error] toml::parse_integer: "
+                           "the next token is not an integer"));
 }
 
 template<typename Container>
@@ -225,8 +222,8 @@ parse_floating(location<Container>& loc)
         return ok(std::make_pair(v, token.unwrap()));
     }
     loc.iter() = first;
-    return err(format_underline("[error] toml::parse_floating: ", loc,
-                "token is not a float", {"floating point is like: -3.14e+1"}));
+    return err(std::string("[error] toml::parse_floating: "
+                           "the next token is not a float"));
 }
 
 template<typename Container>
@@ -286,9 +283,8 @@ result<std::string, std::string> parse_escape_sequence(location<Container>& loc)
     const auto first = loc.iter();
     if(first == loc.end() || *first != '\\')
     {
-        return err(format_underline("[error]: "
-            "toml::parse_escape_sequence: location does not points \"\\\"",
-            loc, "should be \"\\\""));
+        return err(std::string("[error]: toml::parse_escape_sequence: "
+                    "the next token is not an escape sequence \"\\\""));
     }
     ++loc.iter();
     switch(*loc.iter())
@@ -527,8 +523,8 @@ parse_string(location<Container>& loc)
     if(const auto rslt = parse_ml_literal_string(loc)) {return rslt;}
     if(const auto rslt = parse_basic_string(loc))      {return rslt;}
     if(const auto rslt = parse_literal_string(loc))    {return rslt;}
-    return err(format_underline("[error] toml::parse_string: not a string",
-               loc, "not a string"));
+    return err(std::string("[error] toml::parse_string: "
+                "the next token is not a string"));
 }
 
 template<typename Container>
@@ -576,11 +572,9 @@ parse_local_date(location<Container>& loc)
     }
     else
     {
-        auto msg = format_underline("[error]: toml::parse_local_date: "
-                "invalid format", loc, token.unwrap_err(),
-                {"local date is like: 1979-05-27"});
         loc.iter() = first;
-        return err(std::move(msg));
+        return err(std::string("[error]: toml::parse_local_date: "
+                    "the next token is not a local_date"));
     }
 }
 
@@ -661,11 +655,9 @@ parse_local_time(location<Container>& loc)
     }
     else
     {
-        auto msg = format_underline("[error]: toml::parse_local_time: "
-                "invalid format", loc, token.unwrap_err(),
-                {"local time is like: 00:32:00.999999"});
         loc.iter() = first;
-        return err(std::move(msg));
+        return err(std::string("[error]: toml::parse_local_time: "
+                    "the next token is not a local_time"));
     }
 }
 
@@ -706,11 +698,9 @@ parse_local_datetime(location<Container>& loc)
     }
     else
     {
-        auto msg = format_underline("[error]: toml::parse_local_datetime: "
-                    "invalid format", loc, token.unwrap_err(),
-                    {"local datetime is like: 1979-05-27T00:32:00.999999"});
         loc.iter() = first;
-        return err(std::move(msg));
+        return err(std::string("[error]: toml::parse_local_datetime: "
+                    "the next token is not a local_datetime"));
     }
 }
 
@@ -757,12 +747,9 @@ parse_offset_datetime(location<Container>& loc)
     }
     else
     {
-        auto msg = format_underline("[error]: toml::parse_offset_datetime: "
-                    "invalid format", loc, token.unwrap_err(),
-                    {"offset datetime is like: 1979-05-27T00:32:00-07:00",
-                     "or in UTC (w/o offset) : 1979-05-27T00:32:00Z"});
         loc.iter() = first;
-        return err(std::move(msg));
+        return err(std::string("[error]: toml::parse_offset_datetime: "
+                    "the next token is not a local_datetime"));
     }
 }
 
@@ -781,8 +768,8 @@ result<key, std::string> parse_simple_key(location<Container>& loc)
     {
         return ok(bare.unwrap().str());
     }
-    return err(format_underline("[error] toml::parse_simple_key: "
-        "the next token is not a simple key", loc, "not a key"));
+    return err(std::string("[error] toml::parse_simple_key: "
+        "the next token is not a simple key"));
 }
 
 // dotted key become vector of keys
@@ -835,8 +822,8 @@ result<std::vector<key>, std::string> parse_key(location<Container>& loc)
     {
         return ok(std::vector<key>(1, smpl.unwrap()));
     }
-    return err(format_underline("toml::parse_key: the next token is not a key",
-                loc, "not a key"));
+    return err(std::string("[error] toml::parse_key: "
+                           "the next token is not a key"));
 }
 
 // forward-decl to implement parse_array and parse_table
@@ -854,8 +841,7 @@ parse_array(location<Container>& loc)
     }
     if(*loc.iter() != '[')
     {
-        return err(format_underline("[error] toml::parse_array: "
-            "token is not an array", loc,  "should be ["));
+        return err("[error] toml::parse_array: token is not an array");
     }
     ++loc.iter();
 
@@ -903,13 +889,13 @@ parse_array(location<Container>& loc)
             }
             else
             {
-                return err(format_underline("[error] toml::parse_array: "
-                    "missing array separator `,`", loc, "should be `,`"));
+                throw syntax_error(format_underline("[error] toml::parse_array:"
+                    " missing array separator `,`", loc, "should be `,`"));
             }
         }
     }
     loc.iter() = first;
-    return err(format_underline("[error] toml::parse_array: "
+    throw syntax_error(format_underline("[error] toml::parse_array: "
             "array did not closed by `]`", loc, "should be closed"));
 }
 
@@ -1181,10 +1167,11 @@ parse_inline_table(location<Container>& loc)
     table retval;
     if(!(loc.iter() != loc.end() && *loc.iter() == '{'))
     {
-        return err(format_underline("[error] toml::parse_inline_table: "
-            "the next token is not an inline table", loc, "not `{`."));
+        return err(std::string("[error] toml::parse_inline_table: "
+                               "the next token is not an inline table"));
     }
     ++loc.iter();
+    // it starts from "{". it should be formatted as inline-table
     while(loc.iter() != loc.end())
     {
         maybe<lex_ws>::invoke(loc);
@@ -1224,13 +1211,14 @@ parse_inline_table(location<Container>& loc)
             }
             else
             {
-                return err(format_underline("[error] toml:::parse_inline_table:"
-                    " missing table separator `,` ", loc, "should be `,`"));
+                throw syntax_error(format_underline("[error] "
+                    "toml:::parse_inline_table: missing table separator `,` ",
+                    loc, "should be `,`"));
             }
         }
     }
     loc.iter() = first;
-    return err(format_underline("[error] toml::parse_inline_table: "
+    throw syntax_error(format_underline("[error] toml::parse_inline_table: "
             "inline table did not closed by `}`", loc, "should be closed"));
 }
 
@@ -1357,7 +1345,7 @@ result<table, std::string> parse_ml_table(location<Container>& loc)
         return err(std::string("toml::parse_ml_table: input is empty"));
     }
 
-    // XXX at lest one newline is needed
+    // XXX at lest one newline is needed.
     using skip_line = repeat<
         sequence<maybe<lex_ws>, maybe<lex_comment>, lex_newline>, at_least<1>>;
     skip_line::invoke(loc);
@@ -1377,6 +1365,7 @@ result<table, std::string> parse_ml_table(location<Container>& loc)
             loc.iter() = before;
             return ok(tab);
         }
+
         if(const auto kv = parse_key_value_pair(loc))
         {
             const std::vector<key>& keys = kv.unwrap().first;
@@ -1393,6 +1382,17 @@ result<table, std::string> parse_ml_table(location<Container>& loc)
             return err(kv.unwrap_err());
         }
 
+        // comment lines are skipped by the above function call.
+        // However, since the `skip_line` requires at least 1 newline, it fails
+        // if the file ends with ws and/or comment without newline.
+        // `skip_line` matches `ws? + comment? + newline`, not `ws` or `comment`
+        // itself. To skip the last ws and/or comment, call lexers.
+        // It does not matter if these fails, so the return value is discarded.
+        lex_ws::invoke(loc);
+        lex_comment::invoke(loc);
+
+        // skip_line is (whitespace? comment? newline)_{1,}. multiple empty lines
+        // and comments after the last key-value pairs are allowed.
         const auto newline = skip_line::invoke(loc);
         if(!newline && loc.iter() != loc.end())
         {
@@ -1405,11 +1405,10 @@ result<table, std::string> parse_ml_table(location<Container>& loc)
             return err(msg);
         }
 
-        // comment lines are skipped by the above function call.
-        // However, if the file ends with comment without newline,
-        // it might cause parsing error because skip_line matches
-        // `comment + newline`, not `comment` itself. to skip the
-        // last comment, call lex_comment one more time.
+        // the skip_lines only matches with lines that includes newline.
+        // to skip the last line that includes comment and/or whitespace
+        // but no newline, call them one more time.
+        lex_ws::invoke(loc);
         lex_comment::invoke(loc);
     }
     return ok(tab);
@@ -1498,10 +1497,10 @@ inline table parse(std::istream& is, std::string fname = "unknown file")
     // be compared to char. However, since we are always out of luck, we need to
     // check our chars are equivalent to BOM. To do this, first we need to
     // convert char to unsigned char to guarantee the comparability.
-    if(letters.size() >= 3)
+    if(loc.source()->size() >= 3)
     {
         std::array<unsigned char, 3> BOM;
-        std::memcpy(BOM.data(), letters.data(), 3);
+        std::memcpy(BOM.data(), loc.source()->data(), 3);
         if(BOM[0] == 0xEF && BOM[1] == 0xBB && BOM[2] == 0xBF)
         {
             loc.iter() += 3; // BOM found. skip.

toml/value.hpp

@@ -801,17 +801,21 @@ inline bool operator>=(const toml::value& lhs, const toml::value& rhs)
 }
 
 inline std::string format_error(const std::string& err_msg,
-        const toml::value& v, const std::string& comment)
+        const toml::value& v, const std::string& comment,
+        std::vector<std::string> hints = {})
 {
-    return detail::format_underline(err_msg, detail::get_region(v), comment);
+    return detail::format_underline(err_msg, detail::get_region(v), comment,
+                                    std::move(hints));
 }
 
 inline std::string format_error(const std::string& err_msg,
         const toml::value& v1, const std::string& comment1,
-        const toml::value& v2, const std::string& comment2)
+        const toml::value& v2, const std::string& comment2,
+        std::vector<std::string> hints = {})
 {
     return detail::format_underline(err_msg, detail::get_region(v1), comment1,
-                                             detail::get_region(v2), comment2);
+                                             detail::get_region(v2), comment2,
+                                             std::move(hints));
 }
 
 }// toml