///
/// \mainpage toml++
/// \image html banner_small.png width=1280px
/// \tableofcontents
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-features Features
/// - Supports the latest [TOML](https://toml.io/) release ([v1.0.0](https://toml.io/en/v1.0.0)), plus
///   optional support for some unreleased TOML features
/// - Supports serializing to JSON
/// - Proper UTF-8 handling (incl. BOM)
/// - C++17 (plus some C++20 features where available, e.g. experimental support for char8_t strings)
/// - Header-only (optional!)
/// - Doesn't require RTTI
/// - Works with or without exceptions
/// - Tested on Clang (6+), GCC (7+) and MSVC (VS2019)
/// - Tested on x64, x86 and ARM
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-api-documentation API documentation
/// You're looking at it! Browse the docs using the links at the top of the page.
/// You can search from anywhere by pressing the TAB key.
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-example Basic examples
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-parsing-files Parsing files
/// Call toml::parse_file() and work with the toml::table you get back, or handle any toml::parse_error that gets thrown:
/// 
/// \cpp
/// #include <iostream>
/// #include <fstream> //required for parse_file()
/// #include <toml++/toml.h>
/// 
/// int main(int argc, char** argv)
/// {
/// 	toml::table tbl;
/// 	try
/// 	{
/// 		tbl = toml::parse_file(argv[1]);
///			std::cout << tbl << "\n";
/// 	}
/// 	catch (const toml::parse_error& err)
/// 	{
/// 		std::cerr << "Parsing failed:\n" << err << "\n";
/// 		return 1;
/// 	}
/// 
/// 	return 0;
/// }
/// 
/// \ecpp
/// 
/// \m_class{m-note m-warning}
/// 
/// \parblock
/// <h3>Don't forget [code]\#include &lt;fstream&gt;[/code]!</h3>
/// Not everyone who uses the library is going to work directly from files, so not everybody is forced to pay
/// the compilation overhead of including `<fstream>`. You need to explicitly include it if you're going to be calling
/// toml::parse_file().
/// \endparblock
/// 
/// \see
/// 	- toml::parse_file()  
/// 	- toml::table  
/// 	- toml::parse_error
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-parsing-strings Parsing strings and iostreams
/// 
/// Call toml::parse() and work with the toml::table you get back, or handle any toml::parse_error that gets thrown:
/// 
/// \godbolt{NsR-xf}
/// 
/// \cpp
/// #include <iostream>
/// #include <sstream>
/// #include <toml++/toml.h>
/// using namespace std::string_view_literals;
/// 
/// int main()
/// {
/// 	static constexpr std::string_view some_toml = R"(
/// 		[library]
/// 		name = "toml++"
/// 		authors = ["Mark Gillard <mark.gillard@outlook.com.au>"]
/// 		cpp = 17
/// 	)"sv;
/// 	
/// 	try
/// 	{
/// 		// parse directly from a string view:
/// 		{
/// 			toml::table tbl = toml::parse(some_toml);
/// 			std::cout << tbl << "\n";
/// 		}
/// 		
/// 		// parse from a string stream:
/// 		{
/// 			std::stringstream ss{ std::string{ some_toml } };
/// 			toml::table tbl = toml::parse(ss);
/// 			std::cout << tbl << "\n";
/// 		}
/// 	}
/// 	catch (const toml::parse_error& err)
/// 	{
/// 		std::cerr << "Parsing failed:\n" << err << "\n";
/// 		return 1;
/// 	}
/// 	
/// 	return 0;
/// }
/// \ecpp
/// 
/// \out
/// [library]
/// authors = [ 'Mark Gillard <mark.gillard@outlook.com.au>' ]
/// cpp = 17
/// name = 'toml++'
/// 
/// [library]
/// authors = [ 'Mark Gillard <mark.gillard@outlook.com.au>' ]
/// cpp = 17
/// name = 'toml++'
/// \eout
///
/// \see
/// 	- toml::parse_file()  
/// 	- toml::table  
/// 	- toml::parse_error
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-parsing-without-exceptions Handling errors without exceptions
/// Can't (or won't) use exceptions? That's fine too. You can disable exceptions in your compiler flags and/or
/// explicitly disable the library's use of them by setting the option \ref TOML_EXCEPTIONS to `0`. In either case,
/// the parsing functions return a toml::parse_result instead of a toml::table:
/// 
/// \cpp
/// #include <iostream>
/// #include <fstream>
/// 
/// #define TOML_EXCEPTIONS 0 // only necessary if you've left them enabled in your compiler
/// #include <toml++/toml.h>
/// 
/// int main()
/// {
/// 	toml::parse_result result = toml::parse_file("configuration.toml");
/// 	if (!result)
/// 	{
/// 		std::cerr << "Parsing failed:\n" << result.error() << "\n";
/// 		return 1;
/// 	}
/// 	
/// 	do_stuff_with_your_config(std::move(result).table()); // 'steal' the table from the result
/// 	return 0;
/// }
/// \ecpp
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-custom-error-formatting Custom error formatting
/// The examples above use an overloaded `operator<<` with ostreams to print basic error messages, and look like this:
/// \out
/// Error while parsing key: expected bare key starting character or string delimiter, saw '?'
///     (error occurred at line 2, column 5)
/// \eout
/// 
/// In order to keep the library as small as possible I haven't bent over backwards to support things like custom
/// colouring of the text in TTY environments, et cetera. That being said, the library provides the requisite information 
/// for you to build these yourself if necessary via toml::parse_error's source() and description() members:
/// 
/// \cpp
/// toml::table tbl;
/// try
/// {
/// 	tbl = toml::parse_file("configuration.toml");
/// }
/// catch (const toml::parse_error& err)
/// {
/// 	std::cerr
/// 		<< "Error parsing file '" << *err.source().path
/// 		<< "':\n" << err.description()
/// 		<< "\n  (" << err.source().begin << ")\n";
/// 	return 1;
/// }
/// \ecpp
/// 
/// \see
/// 	- toml::parse_error  
/// 	- toml::source_region  
/// 	- toml::source_position
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-manipulations Working with TOML data
/// A TOML document is a tree of values, arrays and tables, represented as the toml::value, toml::array
/// and toml::table, respectively. All three inherit from toml::node, and can be easily accessed via
/// the toml::node_view:
/// 
/// \godbolt{7z6GGW}
/// 
/// \cpp
/// #include <iostream>
/// #include <toml++/toml.h>
/// using namespace std::string_view_literals;
/// 
/// int main()
/// {
/// 	static constexpr auto source = R"(
/// 		str = "hello world"
/// 		
/// 		numbers = [ 1, 2, 3, "four", 5.0 ]
/// 		vegetables = [ "tomato", "onion", "mushroom", "lettuce" ]
/// 		minerals = [ "quartz", "iron", "copper", "diamond" ]
/// 
/// 		[animals]
/// 		cats = [ "tiger", "lion", "puma" ]
/// 		birds = [ "macaw", "pigeon", "canary" ]
/// 		fish = [ "salmon", "trout", "carp" ]
/// 
/// 	)"sv;
/// 	toml::table tbl = toml::parse(source);
/// 	
/// 	// different ways of directly querying data
/// 	std::optional<std::string_view> str1 = tbl["str"].value<std::string_view>();
/// 	std::optional<std::string>      str2 = tbl["str"].value<std::string>();
/// 	std::string_view                str3 = tbl["str"].value_or(""sv);
/// 	std::string&                    str4 = tbl["str"].ref<std::string>(); // ~~dangerous~~
/// 	
/// 	std::cout << *str1 << "\n";
/// 	std::cout << *str2 << "\n";
/// 	std::cout << str3 << "\n";
/// 	std::cout << str4 << "\n";
/// 	
/// 	// get a toml::node_view of the element 'numbers' using operator[]
/// 	auto numbers = tbl["numbers"];
/// 	std::cout << "table has 'numbers': " << !!numbers << "\n";
/// 	std::cout << "numbers is an: " << numbers.type() << "\n";
/// 	std::cout << "numbers: " << numbers << "\n";
/// 
/// 	// get the underlying array object to do some more advanced stuff
/// 	if (toml::array* arr = numbers.as_array())
/// 	{
/// 		for (toml::node& elem : *arr)
/// 		{
/// 			// visitation helps deal with the polymorphic nature of TOML data
/// 			elem.visit([](auto&& el) noexcept
/// 			{
/// 				if constexpr (toml::is_number<decltype(el)>)
/// 					(*el)++;
/// 				else if constexpr (toml::is_string<decltype(el)>)
/// 					el = "five"sv;
/// 			});
/// 		}
/// 		
/// 		// arrays are very similar to std::vector
/// 		arr->push_back(7);
/// 		arr->emplace_back<toml::array>(8, 9);
/// 		std::cout << "numbers: " << numbers << "\n";
/// 	}
/// 
/// 	// node-views can be chained to quickly query deeper
/// 	std::cout << "cats: " << tbl["animals"]["cats"] << "\n";
/// 	std::cout << "fish[1]: " << tbl["animals"]["fish"][1] << "\n";
/// 	
/// 	// ...even if the element doesn't exist
/// 	std::cout << "dinosaurs: " << tbl["animals"]["dinosaurs"] << "\n"; //no dinosaurs :(
/// 
/// 	return 0;
/// }
/// \ecpp
/// 
/// \out
/// hello world
/// hello world
/// hello world
/// hello world
/// table has 'numbers': 1
/// numbers is an: array
/// numbers: [ 1, 2, 3, 'four', 5.0 ]
/// numbers: [ 2, 3, 4, 'five', 6.0, 7, [ 8, 9 ] ]
/// cats: [ 'tiger', 'lion', 'puma' ]
/// fish[1]: 'trout'
/// dinosaurs: 
/// \eout
/// 
/// \see
/// 	- toml::node
/// 	- toml::node_view
/// 	- toml::value
/// 	- toml::array
/// 	- toml::table
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-serialization Serializing as TOML and JSON
/// All toml++ data types have overloaded `operator<<` for ostreams, so 'serializing' a set of TOML data to actual
/// TOML is done just by printing it to an ostream. Converting it to JSON is done in the same way,
/// but via a toml::json_formatter.
/// 
/// \godbolt{MMNoW4}
/// 
/// \cpp
/// #include <iostream>
/// #include <toml++/toml.h>
/// 
/// int main()
/// {
/// 	auto tbl = toml::table{{
/// 		{ "lib", "toml++" },
/// 		{ "cpp", toml::array{ 17, 20, "and beyond" } },
/// 		{ "toml", toml::array{ "1.0.0", "and beyond" } },
/// 		{ "repo", "https://github.com/marzer/tomlplusplus/" },
/// 		{ "author", toml::table{{
/// 				{ "name", "Mark Gillard" },
/// 				{ "github", "https://github.com/marzer" },
/// 				{ "twitter", "https://twitter.com/marzer8789" }
/// 			}}
/// 		},
/// 	}};
/// 
/// 	// serializing as TOML
/// 	std::cout << "###### TOML ######" << "\n\n";
/// 	std::cout << tbl << "\n\n";
/// 
/// 	// serializing as JSON using toml::json_formatter:
/// 	std::cout << "###### JSON ######" << "\n\n";
/// 	std::cout << toml::json_formatter{ tbl } << "\n\n";
/// 	return 0;
/// }
/// \ecpp
/// 
/// \out
/// ###### TOML ######
/// 
/// cpp = [ 17, 20, 'and beyond' ]
/// lib = 'toml++'
/// repo = 'https://github.com/marzer/tomlplusplus/'
/// toml = [ '1.0.0', 'and beyond' ]
/// 
/// [author]
/// github = 'https://github.com/marzer'
/// name = 'Mark Gillard'
/// twitter = 'https://twitter.com/marzer8789'
/// 
/// ###### JSON ######
/// 
/// {
///     "author" : {
///         "github" : "https://github.com/marzer", 
///         "name" : "Mark Gillard", 
///         "twitter" : "https://twitter.com/marzer8789"
///     }, 
///     "cpp" : [
///         17,
///         20,
///         "and beyond"
///     ], 
///     "lib" : "toml++", 
///     "repo" : "https://github.com/marzer/tomlplusplus/", 
///     "toml" : [
///         "1.0.0",
///         "and beyond"
///     ]
/// }
/// \eout
/// \see
/// 	- toml::default_formatter
/// 	- toml::json_formatter
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-example-speed-up-compilation Speeding up compilation
/// Because toml++ is a header-only library of nontrivial size you might find that compilation times noticeably
/// increase after you add it to your project, especially if you add the library's header somewhere that's visible from
/// a large number of translation units. You can counter this by disabling 'all inline' mode and explicitly controlling
/// where the library's implementation is compiled.
/// 
/// <strong>Step 1: Set \ref TOML_HEADER_ONLY to [code]0[/code] before including toml++</strong>
/// 
/// This must be the same everywhere, so either set it as a global `#define` in your build system, or
/// do it manually before including toml++ in some global header that's used everywhere in your project:
/// \cpp
/// // global_header_that_includes_toml++.h
/// 
/// #define TOML_HEADER_ONLY 0
/// #include <toml.hpp>
/// \ecpp
/// 
/// <strong>Step 2: Define \ref TOML_IMPLEMENTATION before including toml++ in one specific translation unit</strong>
/// 
/// \cpp
/// // some_code_file.cpp
/// 
/// #define TOML_IMPLEMENTATION 
/// #include "global_header_that_includes_toml++.h"
/// \ecpp
/// 
/// <strong>Bonus Step: Disable the parser if you don't need it</strong>
/// 
/// If all you need to do is serialize some code-generated TOML and don't actually need the parser at all you can
/// set \ref TOML_PARSER to `0` to disable the parser altogether. This can yield fairly significant compilation
/// speedups since the parser accounts for a good chunk of the library's code.
/// 
/// 
/// \see \ref configuration
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-adding-lib Adding toml++ to your project
/// 
/// \m_class{m-note m-default}
/// 
/// The library comes in two flavours, [emoji icecream] Single-header
/// and [emoji sundae] Regular. The API is the same for both.
/// 
//////////////////////////////////
/// 
/// \subsection mainpage-adding-lib-old-school "The old fashioned way"
/// Clone \github{marzer/tomlplusplus, the repository} from GitHub, and then:
/// 
/// <h3>[emoji icecream] Single-header flavour</h3>
/// 1. Drop `toml.hpp` wherever you like in your source tree
/// 2. There is no step two
/// 
/// <h3>[emoji sundae] Regular flavour</h3>
/// 1. Add `tomlplusplus/include` to your include paths
/// 2. `#include <toml++/toml.h>`  
///
//////////////////////////////////
///
/// \subsection mainpage-adding-lib-conan Conan
/// Add `tomlplusplus/2.3.0` to your conanfile. This adds the single-header version by default, but you can specify the
/// regular version using `"multiple_headers": True`.
/// 
//////////////////////////////////
///
/// \subsection mainpage-adding-lib-dds DDS
/// Add `tomlpp` to your `package.json5`, e.g.:
/// \bash
/// depends: [
///		'tomlpp^2.3.0',
/// ]
/// \ebash
///
/// \see [What is DDS?](https://dds.pizza/)
///
//////////////////////////////////
///
/// \subsection mainpage-adding-lib-meson Meson
/// The library supports being added as a subproject in the meson build system.
///
//////////////////////////////////
///
/// \subsection mainpage-adding-lib-vcpkg Vcpkg
/// \bash
/// vcpkg install tomlplusplus
/// \ebash
///
//////////////////////////////////
///
/// \subsection mainpage-adding-lib-other Other environments and package managers
/// toml++ is a fairly new project and I'm not up-to-speed with all of the available packaging and integration options
/// in the modern C++ ecosystem. I'm also a cmake novice, for better or worse. If there's an integration option missing
/// be assured that I fully support it being added, and welcome pull requests!
///
//////////////////////////////////
///
/// \subsection mainpage-adding-lib-python Special mention: Python
/// Yes, you read correctly, python. There exists a python wrapper built around toml++ called
/// \github{bobfang1992/pytomlpp, pytomlpp}:
/// 
/// \bash
/// pip install pytomlpp
/// \ebash
/// 
/// Note that I'm not the developer or maintainer of that project so if you wish to report a bug relating to the python
/// implementation, please do so at their repository, not on the main toml++ one.
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-configuration Library configuration options
/// The library exposes a number of configuration options in the form of compiler `#defines`. Things like
/// changing the `optional<T>` type, disabling header-only mode, et cetera. The full list of
/// configurables can be found on the \ref configuration page.
/// 
/// \see \ref configuration
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-contributing Contributing
/// Contributions are very welcome! Either by \github{marzer/tomlplusplus/issues, reporting issues}
/// or submitting pull requests. If you wish to submit a pull request,
/// please see \github{marzer/tomlplusplus/blob/master/CONTRIBUTING.md, CONTRIBUTING}
/// for all the details you need to get going.
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-license License
///  
/// toml++ is licensed under the terms of the MIT license - see
/// [LICENSE](https://github.com/marzer/tomlplusplus/blob/master/LICENSE).
/// 
/// \m_class{m-note m-default}
/// 
/// If you're using the single-header version of the library you don't need to explicitly distribute the license file;
/// it is embedded in the preamble at the top of the header.
/// 
//////////////////////////////////////////////////////////////////////
/// 
/// \section mainpage-contact Contacting the author
/// For bug reports and feature requests please use the \github{marzer/tomlplusplus/issues, Github Issues}
/// system. For anything else you're welcome to reach out via other means. In order of likely response speed:
/// - Twitter: [marzer8789](https://twitter.com/marzer8789)
/// - Email: [mark.gillard@outlook.com.au](mailto:mark.gillard@outlook.com.au)
/// - Facebook: [marzer](https://www.facebook.com/marzer)
/// - LinkedIn: [marzer](https://www.linkedin.com/in/marzer/)  
///