mirror of
https://github.com/ToruNiina/toml11.git
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cbaaaaca7c
I found that in a user-code (I'm also one of the users of this library), this new feature sometimes causes an error. Some of my code won't compile because of this change. Since toml::table is convertible to toml::value *implicitly*, if toml::find(table, key, tablename) was called, the overload resolution becomes ambiguous with toml::find( value, key1, key2). But dropping support for toml::find(toml::table, key, tablename) is a breaking change. So I concluded that now is not the right time yet.
1123 lines
34 KiB
Markdown
1123 lines
34 KiB
Markdown
toml11
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======
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[](https://travis-ci.org/ToruNiina/toml11)
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[](https://ci.appveyor.com/project/ToruNiina/toml11/branch/master)
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[](https://circleci.com/gh/ToruNiina/toml11/tree/master)
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[](https://github.com/ToruNiina/toml11/releases)
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[](LICENSE)
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[](https://doi.org/10.5281/zenodo.1209136)
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toml11 is a C++11 header-only toml parser/encoder depending only on C++ standard library.
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compatible to the latest version of
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[TOML v0.5.0](https://github.com/toml-lang/toml/blob/master/versions/en/toml-v0.5.0.md)
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after version 2.0.0.
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It passes [the language agnostic test suite for TOML parsers by BurntSushi](https://github.com/BurntSushi/toml-test).
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Not only the test suite itself, a TOML reader/encoder also runs on [CircleCI](https://circleci.com/gh/ToruNiina/toml11).
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You can see the error messages about invalid files and serialization results of valid files at
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[CircleCI](https://circleci.com/gh/ToruNiina/toml11).
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## Example
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```cpp
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#include <toml11/toml.hpp>
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#include <iostream>
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int main()
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{
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const auto data = toml::parse("example.toml");
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// title = "an example toml file"
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std::string title = toml::get<std::string>(data.at("title"));
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std::cout << "the title is " << title << std::endl;
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// nums = [1, 2, 3, 4, 5]
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std::vector<int> nums = toml::get<std::vector<int>>(data.at("nums"));
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std::cout << "the length of `nums` is" << nums.size() << std::endl;
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return 0;
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}
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```
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## Table of Contents
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- [Integration](#integration)
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- [Decoding a toml file](#decoding-a-toml-file)
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- [In the case of syntax error](#in-the-case-of-syntax-error)
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- [Getting a toml value](#getting-a-toml-value)
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- [In the case of type error](#in-the-case-of-type-error)
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- [Getting an array](#getting-an-array)
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- [Getting a table](#getting-a-table)
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- [Dotted keys](#dotted-keys)
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- [Getting an array of tables](#getting-an-array-of-tables)
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- [Cost of conversion](#cost-of-conversion)
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- [Getting datetime and its variants](#getting-datetime-and-its-variants)
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- [Getting with a fallback](#getting-with-a-fallback)
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- [Expecting conversion](#expecting-conversion)
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- [Finding a value from a table](#finding-a-value-from-a-table)
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- [Checking value type](#checking-value-type)
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- [Visiting a toml::value](#visiting-a-tomlvalue)
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- [TOML literal](#toml-literal)
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- [Conversion between toml value and arbitrary types](#conversion-between-toml-value-and-arbitrary-types)
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- [Invalid UTF-8 Codepoints](#invalid-utf-8-codepoints)
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- [Formatting user-defined error messages](#formatting-user-defined-error-messages)
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- [Getting comments related to a value](#getting-comments)
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- [Serializing TOML data](#serializing-toml-data)
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- [Underlying types](#underlying-types)
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- [Running Tests](#running-tests)
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- [Contributors](#contributors)
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- [Licensing Terms](#licensing-terms)
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## Integration
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Just include the file after adding it to the include path.
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```cpp
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#include <toml11/toml.hpp> // that's all! now you can use it.
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#include <iostream>
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int main()
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{
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const auto data = toml::parse("example.toml");
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const auto title = toml::get<std::string>(data.at("title"));
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std::cout << "the title is " << title << std::endl;
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return 0;
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}
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```
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## Decoding a toml file
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To parse a toml file, the only thing you have to do is
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to pass a filename to the `toml::parse` function.
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```cpp
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const std::string fname("sample.toml");
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const toml::table data = toml::parse(fname);
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```
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If it encounters a file open error, it will throw `std::runtime_error`.
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You can also pass a `std::istream` to the `toml::parse` function.
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To show a filename in an error message, it is recommended to pass the filename
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with the stream.
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```cpp
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std::ifstream ifs("sample.toml", std::ios_base::binary);
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assert(ifs.good());
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const auto data = toml::parse(ifs, /*optional*/ "sample.toml");
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```
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Note that on Windows, if a file is opened in text-mode, CRLF ("\r\n") will
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automatically be converted to LF ("\n") and this causes inconsistency between
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file size and the contents that would be read. This causes weird error.
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To use a file stream with `toml::parse` on Windows, don't forget to open it
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in binary mode.
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### In the case of syntax error
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If there is a syntax error in a toml file, `toml::parse` will throw `toml::syntax_error`.
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toml11 has clean and informative error messages inspired by Rust and
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it looks like the following.
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```console
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terminate called after throwing an instance of 'toml::syntax_error'
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what(): [error] toml::parse_table: invalid line format # error description
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--> example.toml # file name
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3 | a = 42 = true # line num and content
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| ^------ expected newline, but got '='. # error reason
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```
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If you (mistakenly) duplicate tables and got an error, it is helpful to see
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where they are. toml11 shows both at the same time like the following.
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```console
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terminate called after throwing an instance of 'toml::syntax_error'
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what(): [error] toml::insert_value: table ("table") already exists.
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--> duplicate-table.toml
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1 | [table]
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| ~~~~~~~ table already exists here
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...
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3 | [table]
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| ~~~~~~~ table defined twice
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```
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Since the error message generation is generally a difficult task, the current
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status is not ideal. If you encounter a weird error message, please let us know
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and contribute to improve the quality!
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## Getting a toml value
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After parsing successfully, you can obtain the values from the result of
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`toml::parse` using `toml::get` function.
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```toml
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# sample.toml
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answer = 42
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pi = 3.14
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numbers = [1,2,3]
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time = 1979-05-27T07:32:00Z
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[tab]
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key = "value"
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```
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``` cpp
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const auto data = toml::parse("sample.toml");
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const auto answer = toml::get<std::int64_t >(data.at("answer"));
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const auto pi = toml::get<double >(data.at("pi"));
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const auto numbers = toml::get<std::vector<int>>(data.at("numbers"));
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const auto timepoint = toml::get<std::chrono::system_clock::time_point>(data.at("time"));
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const auto tab = toml::get<toml::Table>(data.at("tab"));
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const auto key = toml::get<std::string>( tab.at("key"));
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```
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When you pass an exact TOML type that does not require type conversion,
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`toml::get` returns a reference through which you can modify the content.
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```cpp
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auto data = toml::parse("sample.toml");
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auto& answer = toml::get<toml::integer>(data["answer"]); // get reference
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answer = 6 * 9; // write to data.answer
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std::cout << toml::get<int>(data.at("answer")) << std::endl; // 54
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```
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If the specified type requires conversion, you can't take a reference to the value.
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See also [underlying types](#underlying-types).
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NOTE: To enable to get a reference, conversions between Float and Integer are not supported.
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After C++17, you can use `std::string_view` to get a string from a `toml::value`.
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```cpp
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const auto sv = toml::get<std::string_view>(tab.at("key"));
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```
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### In the case of type error
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If you pass an invalid type to `toml::get`, `toml::type_error` will be thrown.
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Similar to the case of syntax error, toml11 also displays clean error messages.
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The error message when you choose `int` to get `string` value would be like this.
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```console
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terminate called after throwing an instance of 'toml::type_error'
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what(): [error] toml::value bad_cast to integer
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--> example.toml
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3 | title = "TOML Example"
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| ~~~~~~~~~~~~~~ the actual type is string
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```
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NOTE: In order to show this kind of error message, all the toml values have
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pointers to represent its range in a file. The entire contents of a file is
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shared by `toml::value`s and remains on the heap memory. It is recommended to
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destruct all the `toml::value` classes after configuring your application
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if you have a large TOML file compared to the memory resource.
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## Getting an array
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You can get any kind of `container` class from a `toml::array`
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except for `map`-like classes.
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``` cpp
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// # sample.toml
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// numbers = [1,2,3]
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const auto vc = toml::get<std::vector<int> >(data.at("numbers"));
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const auto ls = toml::get<std::list<int> >(data.at("numbers"));
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const auto dq = toml::get<std::deque<int> >(data.at("numbers"));
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const auto ar = toml::get<std::array<int, 3>>(data.at("numbers"));
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// if the size of data.at("numbers") is larger than that of std::array,
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// it will throw toml::type_error because std::array is not resizable.
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```
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Surprisingly, you can also get `std::pair`s and `std::tuple`s from `toml::array`.
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```cpp
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const auto tp = toml::get<std::tuple<short, int, unsigned int>>(data.at("numbers"));
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```
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This functionality is helpful when you have the following toml file.
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```toml
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array_of_arrays = [[1, 2, 3], ["foo", "bar", "baz"]] # toml allows this
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```
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What is the corresponding C++ type? Obviously, it is a `std::pair` of `std::vector`s.
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```cpp
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const auto aofa = toml::get<
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std::pair<std::vector<int>, std::vector<std::string>>
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>(data.at("array_of_arrays"));
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```
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If you don't know the type of the elements, you can use `toml::array`,
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which is a `std::vector` of `toml::value`, instead.
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```cpp
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const auto aofa = toml::get<toml::array>(data.at("array_of_arrays"));
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const auto first = toml::get<std::vector<int>>(aofa.at(0));
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```
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See also [expecting conversion](#expecting-conversion)
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and [checking-value-type](#checking-value-type).
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## Getting a table
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`toml::table` is a key component of this library, which is an alias of
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a `std::unordered_map` from `toml::key (a.k.a. std::string)` to `toml::value`.
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`toml::parse` returns this.
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Since it is just an alias of `std::unordered_map`, it has all the functionalities
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that `std::unordered_map` has, e.g. `operator[]`, `count`, and `find`.
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```cpp
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toml::table data = toml::parse("example.toml");
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if(data.count("title") != 0)
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{
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data["title"] = std::string("TOML example");
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}
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```
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When all the values of the table have the same type, toml11 allows you to
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convert a `toml::table` to a `map` that contains the convertible type.
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```toml
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[tab]
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key1 = "foo" # all the values are
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key2 = "bar" # toml String
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```
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```cpp
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const auto data = toml::parse("sample.toml");
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const auto tab = toml::get<std::map<std::string, std::string>>(data.at("tab"));
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std::cout << tab["key1"] << std::endl; // foo
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std::cout << tab["key2"] << std::endl; // bar
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```
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## Dotted keys
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TOML v0.5.0 has a new feature named "dotted keys".
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You can chain keys to represent the structure of the data.
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```toml
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physical.color = "orange"
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physical.shape = "round"
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```
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This is equivalent to the following.
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```toml
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[physical]
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color = "orange"
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shape = "round"
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```
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You can get both of the above formats with the same c++ code.
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```cpp
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const auto physical = toml::get<toml::table>(data.at("physical"));
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const auto color = toml::get<std::string>(physical.at("color"));
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```
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## Getting an array of tables
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An array of tables is just an array of tables.
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You can get it completely in the same way as the other arrays and tables.
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```toml
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# sample.toml
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array_of_inline_tables = [{key = "value1"}, {key = "value2"}, {key = "value3"}]
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[[array_of_tables]]
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key = "value4"
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[[array_of_tables]]
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key = "value5"
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[[array_of_tables]]
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key = "value6"
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```
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```cpp
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const auto data = toml::parse("sample.toml");
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const auto aot1 = toml::get<std::vector<toml::table>>(data.at("array_of_inline_tables"));
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const auto aot2 = toml::get<std::vector<toml::table>>(data.at("array_of_tables"));
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```
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## Cost of conversion
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Although `toml::get` is convenient, it has additional copy-cost because
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it copies data contained in `toml::value` to the user-specified type.
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Of course in some cases this overhead is not ignorable.
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```cpp
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// the following code constructs a std::vector.
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// it requires heap allocation for vector and element conversion.
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const auto array = toml::get<std::vector<int>>(data.at("foo"));
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```
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By passing the exact types, `toml::get` returns reference that has no overhead.
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``` cpp
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const auto& tab = toml::get<toml::array>(data.at("tab"));
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const auto& numbers = toml::get<toml::table>(data.at("numbers"));
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```
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In this case you need to call `toml::get` each time you access to
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the element of `toml::array` because `toml::array` is an array of `toml::value`.
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```cpp
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const auto& num0 = toml::get<toml::integer>(numbers.at(0));
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const auto& num1 = toml::get<toml::integer>(numbers.at(1));
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const auto& num2 = toml::get<toml::integer>(numbers.at(2));
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```
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## Getting datetime and its variants
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TOML v0.5.0 has 4 different datetime objects, `local_date`, `local_time`,
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`local_datetime`, and `offset_datetime`.
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Since `local_date`, `local_datetime`, and `offset_datetime` represent a time
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point, you can convert them to `std::chrono::system_clock::time_point`.
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Contrary, `local_time` does not represents a time point because they lack a
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date information, but it can be converted to `std::chrono::duration` that
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represents a duration from the beginning of the day, `00:00:00.000`.
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```toml
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date = 2018-12-23
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time = 12:30:00
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l_dt = 2018-12-23T12:30:00
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o_dt = 2018-12-23T12:30:00+09:30
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```
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```cpp
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const auto data = toml::parse("sample.toml");
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const auto date = toml::get<std::chrono::system_clock::time_point>(data.at("date"));
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const auto l_dt = toml::get<std::chrono::system_clock::time_point>(data.at("l_dt"));
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const auto o_dt = toml::get<std::chrono::system_clock::time_point>(data.at("o_dt"));
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const auto time = toml::get<std::chrono::minutes>(data.at("time")); // 12 * 60 + 30 min
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```
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toml11 contains datetime as its own struct.
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You can see the definitions in [toml/datetime.hpp](toml/datetime.hpp).
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## Getting with a fallback
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`toml::get_or` returns a default value if `toml::get<T>` failed.
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```cpp
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toml::value v("foo"); // v contains String
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const int value = toml::get_or(v, 42); // conversion fails. it returns 42.
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```
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`toml::get_or` automatically deduces what type you want to get from
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the default value you passed.
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To get a reference through this function, take care about the default value.
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```cpp
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toml::value v("foo"); // v contains String
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toml::integer& i = toml::get_or(v, 42); // does not work because binding `42`
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// to `integer&` is invalid
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toml::integer opt = 42;
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toml::integer& i = toml::get_or(v, opt); // this works.
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```
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## Expecting conversion
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By using `toml::expect`, you will get your expected value or an error message
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without throwing `toml::type_error`.
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```cpp
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const auto value = toml::expect<std::string>(data.at("title"));
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if(value.is_ok()) {
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std::cout << value.unwrap() << std::endl;
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} else {
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std::cout << value.unwrap_err() << std::endl;
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}
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```
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Also, you can pass a function object to modify the expected value.
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```cpp
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const auto value = toml::expect<int>(data.at("number"))
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.map(// function that receives expected type (here, int)
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[](const int number) -> double {
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return number * 1.5 + 1.0;
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}).unwrap_or(/*default value =*/ 3.14);
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```
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## Finding a value from a table
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toml11 provides utility function to find a value from `toml::table`.
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Of course, you can do this in your own way with `toml::get` because
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it just searches an `unordered_map` and returns a value if it exists.
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```cpp
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const auto data = toml::parse("example.toml");
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const auto num = toml::find<int>(data, "num", /*for err msg*/"example.toml");
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```
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If the value does not exist, it throws `std::out_of_range` with an error message.
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```console
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terminate called after throwing an instance of 'std::out_of_range'
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what(): [error] key "num" not found in example.toml
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```
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|
|
You can use this with a `toml::value` that is expected to be a `toml::table`.
|
|
It automatically casts the value to table.
|
|
|
|
```cpp
|
|
const auto data = toml::parse("example.toml");
|
|
const auto num = toml::find<int>(data.at("table"), "num");
|
|
// expecting the following example.toml
|
|
// [table]
|
|
// num = 42
|
|
```
|
|
|
|
In this case, because the value `data.at("table")` knows the locatoin of itself,
|
|
you don't need to pass where you find the value.
|
|
`toml::find` will show you an error message including table location.
|
|
|
|
```console
|
|
terminate called after throwing an instance of 'std::out_of_range'
|
|
what(): [error] key "num" not found
|
|
--> example.toml
|
|
3 | [table]
|
|
| ~~~~~~~ in this table
|
|
```
|
|
|
|
If it's not a `toml::table`, the same error as "invalid type" would be thrown.
|
|
|
|
There is another utility function, `toml::find_or`.
|
|
It is almost same as `toml::find`, but returns a default value if the value is
|
|
not found or has a different type, like `toml::get_or`.
|
|
|
|
```cpp
|
|
const auto data = toml::parse("example.toml");
|
|
const auto num = toml::find_or(data.at("table"), "num", 42);
|
|
```
|
|
|
|
## Checking value type
|
|
|
|
You can check what type of value does `toml::value` contains by `is_*` function.
|
|
|
|
```cpp
|
|
toml::value v = /* ... */;
|
|
if(v.is_integer())
|
|
{
|
|
std::cout << "value is an integer" << std::endl;
|
|
}
|
|
```
|
|
|
|
The complete list of the functions is below.
|
|
|
|
```cpp
|
|
namespace toml {
|
|
class value {
|
|
// ...
|
|
bool is_boolean() const noexcept;
|
|
bool is_integer() const noexcept;
|
|
bool is_floating() const noexcept;
|
|
bool is_string() const noexcept;
|
|
bool is_offset_datetime() const noexcept;
|
|
bool is_local_datetime() const noexcept;
|
|
bool is_local_date() const noexcept;
|
|
bool is_local_time() const noexcept;
|
|
bool is_array() const noexcept;
|
|
bool is_table() const noexcept;
|
|
bool is_uninitialized() const noexcept;
|
|
// ...
|
|
};
|
|
} // toml
|
|
```
|
|
|
|
__NOTE__: `is_float` is marked as deprecated since v2.4.0 to make the function names consistent with snake case typenames. Please use `is_floating` instead.
|
|
|
|
Also, you can get `enum class` value from `toml::value`.
|
|
|
|
```cpp
|
|
switch(data.at("something").type())
|
|
{
|
|
case toml::value_t::Integer: /*do some stuff*/ ; break;
|
|
case toml::value_t::Float : /*do some stuff*/ ; break;
|
|
case toml::value_t::String : /*do some stuff*/ ; break;
|
|
default : throw std::runtime_error(
|
|
"unexpected type : " + toml::stringize(data.at("something").type()));
|
|
}
|
|
```
|
|
|
|
The complete list of the `enum`s can be found in the section
|
|
[underlying types](#underlying-types).
|
|
|
|
The `enum`s can be used as a parameter of `toml::value::is` function like the following.
|
|
|
|
```cpp
|
|
toml::value v = /* ... */;
|
|
if(v.is(toml::value_t::Boolean)) // ...
|
|
```
|
|
|
|
## Casting value
|
|
|
|
So far, `toml::get` is introduced, but if you don't need any type conversion,
|
|
`as_*` is simpler to use.
|
|
|
|
```cpp
|
|
toml::value v = /* ... */;
|
|
if(v.is_integer() && v.as_integer() == 42)
|
|
{
|
|
std::cout << "value is 42" << std::endl;
|
|
}
|
|
```
|
|
|
|
`as_*` functions internally checks the current contained type for safety and
|
|
throws `toml::type_error` if the contained value type is different (after toml11
|
|
v2.4.0). If you already confirmed that the value has the type you will cast
|
|
into, you can skip the additional checking by passing `std::nothrow` object to it.
|
|
|
|
```cpp
|
|
toml::value v = /* ... */;
|
|
if(v.is_integer() && v.as_integer(std::nothrow) == 42) // never fail
|
|
{
|
|
std::cout << "value is 42" << std::endl;
|
|
}
|
|
```
|
|
|
|
The full list of the functions is below.
|
|
|
|
```cpp
|
|
namespace toml {
|
|
class value {
|
|
// ...
|
|
const boolean& as_boolean() const&;
|
|
const integer& as_integer() const&;
|
|
const floating& as_floating() const&;
|
|
const string& as_string() const&;
|
|
const offset_datetime& as_offset_datetime() const&;
|
|
const local_datetime& as_local_datetime() const&;
|
|
const local_date& as_local_date() const&;
|
|
const local_time& as_local_time() const&;
|
|
const array& as_array() const&;
|
|
const table& as_table() const&;
|
|
// --------------------------------------------------------
|
|
// non-const version
|
|
boolean& as_boolean() &;
|
|
// ditto...
|
|
// --------------------------------------------------------
|
|
// rvalue version
|
|
boolean&& as_boolean() &&;
|
|
// ditto...
|
|
|
|
// --------------------------------------------------------
|
|
// noexcept versions ...
|
|
const boolean& as_boolean(const std::nothrow_t&) const& noexcept;
|
|
boolean& as_boolean(const std::nothrow_t&) & noexcept;
|
|
boolean&& as_boolean(const std::nothrow_t&) && noexcept;
|
|
// ditto...
|
|
};
|
|
} // toml
|
|
```
|
|
|
|
__NOTE__: `as_float` is marked as deprecated since v2.4.0 to make the function names consistent with snake case typenames. Please use `as_floating` instead.
|
|
|
|
## Visiting a toml::value
|
|
|
|
toml11 provides `toml::visit` to apply a function to `toml::value` in the
|
|
same way as `std::variant`.
|
|
|
|
```cpp
|
|
const toml::value v(3.14);
|
|
toml::visit([](const auto& val) -> void {
|
|
std::cout << val << std::endl;
|
|
}, v);
|
|
```
|
|
|
|
The function object that would be passed to `toml::visit` must be able to
|
|
recieve all the possible TOML types. Also, the result types should be the same
|
|
each other.
|
|
|
|
## TOML literal
|
|
|
|
toml11 supports `"..."_toml` literal.
|
|
It accept both a bare value and a file content.
|
|
|
|
```cpp
|
|
using namespace toml::literals::toml_literals;
|
|
|
|
// `_toml` can convert a bare value without key
|
|
const toml::value v = u8"0xDEADBEEF"_toml;
|
|
// v is an Integer value containing 0xDEADBEEF.
|
|
|
|
// raw string literal (`R"(...)"` is useful for this purpose)
|
|
const toml::value t = u8R"(
|
|
title = "this is TOML literal"
|
|
[table]
|
|
key = "value"
|
|
)"_toml;
|
|
// the literal will be parsed and the result will be contained in t
|
|
```
|
|
|
|
The literal function is defined in the same way as the standard library literals
|
|
such as `std::literals::string_literals::operator""s`.
|
|
|
|
```cpp
|
|
namespace toml
|
|
{
|
|
inline namespace literals
|
|
{
|
|
inline namespace toml_literals
|
|
{
|
|
toml::value operator""_toml(const char* str, std::size_t len);
|
|
|
|
} // toml_literals
|
|
} // literals
|
|
} // toml
|
|
```
|
|
|
|
Access to the operator can be gained with `using namespace toml::literals;`,
|
|
`using namespace toml::toml_literals`, and `using namespace toml::literals::toml_literals`.
|
|
|
|
Note that a key that is composed only of digits is allowed in TOML.
|
|
And, unlike the file parser, toml-literal allows a bare value without a key.
|
|
Thus it is difficult to distinguish arrays having integers and definitions of
|
|
tables that are named as digits.
|
|
Currently, literal `[1]` becomes a table named "1".
|
|
To ensure a literal to be considered as an array with one element, you need to
|
|
add a comma after the first element (like `[1,]`).
|
|
|
|
```cpp
|
|
"[1,2,3]"_toml; // This is an array
|
|
"[table]"_toml; // This is a table that has an empty table named "table" inside.
|
|
"[[1,2,3]]"_toml; // This is an array of arrays
|
|
"[[table]]"_toml; // This is a table that has an array of tables inside.
|
|
|
|
"[[1]]"_toml; // This literal is ambiguous.
|
|
// Currently, it becomes a table that has array of table "1".
|
|
"1 = [{}]"_toml; // This is a table that has an array of table named 1.
|
|
"[[1,]]"_toml; // This is an array of arrays.
|
|
"[[1],]"_toml; // ditto.
|
|
```
|
|
|
|
## Conversion between toml value and arbitrary types
|
|
|
|
You can also use `toml::get` and other related functions with the types you defined
|
|
after you implement some stuff.
|
|
|
|
```cpp
|
|
namespace ext
|
|
{
|
|
struct foo
|
|
{
|
|
int a;
|
|
double b;
|
|
std::string c;
|
|
};
|
|
} // ext
|
|
|
|
const auto data = toml::parse("example.toml");
|
|
|
|
const foo f = toml::get<ext::foo>(data.at("foo"));
|
|
```
|
|
|
|
There are 2 ways to use `toml::get` with the types that you defined.
|
|
|
|
The first one is to implement `from_toml(const toml::value&)` member function.
|
|
|
|
```cpp
|
|
namespace ext
|
|
{
|
|
struct foo
|
|
{
|
|
int a;
|
|
double b;
|
|
std::string c;
|
|
|
|
void from_toml(const toml::value& v)
|
|
{
|
|
this->a = toml::find<int >(v, "a");
|
|
this->b = toml::find<double >(v, "b");
|
|
this->c = toml::find<std::string>(v, "c");
|
|
return;
|
|
}
|
|
};
|
|
} // ext
|
|
```
|
|
|
|
In this way, because `toml::get` first constructs `foo` without arguments,
|
|
the type should be default-constructible.
|
|
|
|
The second is to implement specialization of `toml::from` for your type.
|
|
|
|
```cpp
|
|
namespace ext
|
|
{
|
|
struct foo
|
|
{
|
|
int a;
|
|
double b;
|
|
std::string c;
|
|
};
|
|
} // ext
|
|
|
|
namespace toml
|
|
{
|
|
template<>
|
|
struct from<ext::foo>
|
|
{
|
|
ext::foo from_toml(const toml::value& v)
|
|
{
|
|
ext::foo f;
|
|
f.a = toml::find<int >(v, "a");
|
|
f.b = toml::find<double >(v, "b");
|
|
f.c = toml::find<std::string>(v, "c");
|
|
return f;
|
|
}
|
|
};
|
|
} // toml
|
|
```
|
|
|
|
In this way, since the conversion function is defined outside of the class,
|
|
you can add conversion between `toml::value` and classes defined in another library.
|
|
|
|
Note that you cannot implement both of the functions because the overload
|
|
resolution of `toml::get` will be ambiguous.
|
|
|
|
----
|
|
|
|
The opposite direction is also supported in a similar way. You can directly
|
|
pass your type to `toml::value`'s constructor by introducing `into_toml` or
|
|
`toml::into<T>`.
|
|
|
|
```cpp
|
|
namespace ext
|
|
{
|
|
struct foo
|
|
{
|
|
int a;
|
|
double b;
|
|
std::string c;
|
|
|
|
toml::table into_toml() const // you need to mark it const.
|
|
{
|
|
return toml::table{{"a", this->a}, {"b", this->b}, {"c", this->c}};
|
|
}
|
|
};
|
|
} // ext
|
|
|
|
ext::foo f{42, 3.14, "foobar"};
|
|
toml::value v(f);
|
|
```
|
|
|
|
The definition of `toml::into<T>` is similar to `toml::from<T>`.
|
|
|
|
```cpp
|
|
namespace ext
|
|
{
|
|
struct foo
|
|
{
|
|
int a;
|
|
double b;
|
|
std::string c;
|
|
};
|
|
} // ext
|
|
|
|
namespace toml
|
|
{
|
|
template<>
|
|
struct into<ext::foo>
|
|
{
|
|
toml::table into_toml(const ext::foo& f)
|
|
{
|
|
return toml::table{{"a", f.a}, {"b", f.b}, {"c", f.c}};
|
|
}
|
|
};
|
|
} // toml
|
|
|
|
ext::foo f{42, 3.14, "foobar"};
|
|
toml::value v(f);
|
|
```
|
|
|
|
Any type that can be converted to `toml::value`, e.g. `toml::table`, `toml::array`,
|
|
is okay to return from `into_toml`.
|
|
|
|
## Invalid UTF-8 codepoints
|
|
|
|
toml11 throws `syntax_error` if a value of an escape sequence
|
|
representing unicode character is not a valid UTF-8 codepoint.
|
|
|
|
```console
|
|
what(): [error] toml::read_utf8_codepoint: input codepoint is too large.
|
|
--> utf8.toml
|
|
1 | exceeds_unicode = "\U0011FFFF example"
|
|
| ^--------- should be in [0x00..0x10FFFF]
|
|
```
|
|
|
|
## Formatting user-defined error messages
|
|
|
|
When you encounter an error after you read the toml value, you may want to
|
|
show the error with the value.
|
|
|
|
toml11 provides you a function that formats user-defined error message with
|
|
related values. With a code like the following,
|
|
|
|
```cpp
|
|
const auto value = toml::find<int>(data, "num");
|
|
if(value < 0)
|
|
{
|
|
std::cerr << toml::format_error("[error] value should be positive",
|
|
data.at("num"), "positive number required")
|
|
<< std::endl;
|
|
}
|
|
```
|
|
|
|
you will get an error message like this.
|
|
|
|
```console
|
|
[error] value should be positive
|
|
--> example.toml
|
|
3 | num = -42
|
|
| ~~~ positive number required
|
|
```
|
|
|
|
When you pass two values to `toml::format_error`,
|
|
|
|
```cpp
|
|
const auto min = toml::find<int>(range, "min");
|
|
const auto max = toml::find<int>(range, "max");
|
|
if(max < min)
|
|
{
|
|
std::cerr << toml::format_error("[error] max should be larger than min",
|
|
data.at("min"), "minimum number here",
|
|
data.at("max"), "maximum number here");
|
|
<< std::endl;
|
|
}
|
|
```
|
|
|
|
you will get an error message like this.
|
|
|
|
```console
|
|
[error] max should be larger than min
|
|
--> example.toml
|
|
3 | min = 54
|
|
| ~~ minimum number here
|
|
...
|
|
4 | max = 42
|
|
| ~~ maximum number here
|
|
```
|
|
|
|
## Getting comments
|
|
|
|
Since toml11 keeps a file data until all the values are destructed, you can
|
|
also extract a comment related to a value by calling `toml::value::comment()`.
|
|
|
|
If there is a comment just after a value (within the same line), you can get
|
|
the specific comment by `toml::value::comment_inline()`.
|
|
|
|
If there are comments just before a value (without any newline between them),
|
|
you can get the comments by `toml::value::comment_before()`.
|
|
|
|
`toml::value::comment()` returns the results of both functions after
|
|
concatenating them.
|
|
|
|
```toml
|
|
a = 42 # comment for a.
|
|
|
|
# comment for b.
|
|
# this is also a comment for b.
|
|
b = "foo"
|
|
|
|
c = [ # comment for c.
|
|
3.14, # this is not a comment for c, but for 3.14.
|
|
] # this is also a comment for c.
|
|
```
|
|
|
|
```cpp
|
|
// "# comment for a."
|
|
const std::string com1 = toml::find(data, "a").comment();
|
|
|
|
// "# comment for b."
|
|
const std::string com2 = toml::find(data, "b").comment();
|
|
|
|
// "# comment for c.\n# this is also a comment for c."
|
|
const std::string com3 = toml::find(data, "c").comment();
|
|
|
|
// "# this is not a comment for c, but for 3.14."
|
|
const std::string com3 = toml::find<toml::array>(data, "c").front().comment();
|
|
```
|
|
|
|
Note that once a data in a value is modified, the related file region
|
|
information would be deleted. Thus after modifying a data, you cannot find any
|
|
comments.
|
|
|
|
Also note that currently it does not support any way to set a comment to a value.
|
|
And currently, serializer does not take comments into account.
|
|
|
|
## Serializing TOML data
|
|
|
|
toml11 (after v2.1.0) enables you to serialize data into toml format.
|
|
|
|
```cpp
|
|
const auto data = toml::table{{"foo", 42}, {"bar", "baz"}};
|
|
std::cout << data << std::endl;
|
|
// bar = "baz"
|
|
// foo = 42
|
|
```
|
|
|
|
toml11 automatically makes a small table and small array inline.
|
|
You can specify the width to make them inline by `std::setw` for streams.
|
|
|
|
```cpp
|
|
const auto data = toml::table{
|
|
{"qux", toml::table{{"foo", 42}, {"bar", "baz"}}},
|
|
{"quux", toml::array{"small", "array", "of", "strings"}},
|
|
{"foobar", toml::array{"this", "array", "of", "strings", "is", "too", "long",
|
|
"to", "print", "into", "single", "line", "isn't", "it?"}},
|
|
};
|
|
|
|
// the threshold becomes 80.
|
|
std::cout << std::setw(80) << data << std::endl;
|
|
// foobar = [
|
|
// "this","array","of","strings","is","too","long","to","print","into",
|
|
// "single","line","isn't","it?",
|
|
// ]
|
|
// quux = ["small","array","of","strings"]
|
|
// qux = {bar="baz",foo=42}
|
|
|
|
|
|
// the width is 0. nothing become inline.
|
|
std::cout << std::setw(0) << data << std::endl;
|
|
// foobar = [
|
|
// "this",
|
|
// ... (snip)
|
|
// "it?",
|
|
// ]
|
|
// quux = [
|
|
// "small",
|
|
// "array",
|
|
// "of",
|
|
// "strings",
|
|
// ]
|
|
// [qux]
|
|
// bar = "baz"
|
|
// foo = 42
|
|
```
|
|
|
|
It is recommended to set width before printing data. Some I/O functions changes
|
|
width to 0, and it makes all the stuff (including `toml::array`) multiline.
|
|
The resulting files becomes too long.
|
|
|
|
To control the precision of floating point numbers, you need to pass
|
|
`std::setprecision` to stream.
|
|
|
|
```cpp
|
|
const auto data = toml::table{
|
|
{"pi", 3.141592653589793},
|
|
{"e", 2.718281828459045}
|
|
};
|
|
std::cout << std::setprecision(17) << data << std::endl;
|
|
// e = 2.7182818284590451
|
|
// pi = 3.1415926535897931
|
|
std::cout << std::setprecision( 7) << data << std::endl;
|
|
// e = 2.718282
|
|
// pi = 3.141593
|
|
```
|
|
|
|
There is another way to format toml values, `toml::format()`.
|
|
It returns `std::string` that represents a value.
|
|
|
|
```cpp
|
|
const toml::value v{{"a", 42}};
|
|
const std::string fmt = toml::format(v);
|
|
// a = 42
|
|
```
|
|
|
|
Note that since `toml::format` formats a value, the resulting string may lack
|
|
the key value.
|
|
|
|
```cpp
|
|
const toml::value v{3.14};
|
|
const std::string fmt = toml::format(v);
|
|
// 3.14
|
|
```
|
|
|
|
To control the width and precision, `toml::format` receives optional second and
|
|
third arguments to set them. By default, the witdh is 80 and the precision is
|
|
`std::numeric_limits<double>::max_digit10`.
|
|
|
|
```cpp
|
|
const auto serial = toml::format(data, /*width = */ 0, /*prec = */ 17);
|
|
```
|
|
|
|
## Underlying types
|
|
|
|
The toml types (can be used as `toml::*` in this library) and corresponding `enum` names are listed in the table below.
|
|
|
|
| toml::type | underlying c++ type | enum |
|
|
| -------------- | -------------------------------------------- | ------------------------------- |
|
|
| Boolean | `bool` | `toml::value_t::Boolean` |
|
|
| Integer | `std::int64_t` | `toml::value_t::Integer` |
|
|
| Float | `double` | `toml::value_t::Float` |
|
|
| String | `toml::string` | `toml::value_t::String` |
|
|
| LocalDate | `toml::local_date` | `toml::value_t::LocalDate` |
|
|
| LocalTime | `toml::local_time` | `toml::value_t::LocalTime` |
|
|
| LocalDatetime | `toml::local_datetime` | `toml::value_t::LocalDatetime` |
|
|
| OffsetDatetime | `toml::offset_datetime` | `toml::value_t::OffsetDatetime` |
|
|
| Array | `std::vector<toml::value>` | `toml::value_t::Array` |
|
|
| Table | `std::unordered_map<toml::key, toml::value>` | `toml::value_t::Table` |
|
|
|
|
`toml::string` is effectively the same as `std::string` but has an additional
|
|
flag that represents a kind of a string, `string_t::basic` and `string_t::literal`.
|
|
Although `std::string` is not an exact toml type, still you can get a reference
|
|
that points to internal `std::string` by using `toml::get<std::string>()` for convenience.
|
|
|
|
`Datetime` variants are `struct` that are defined in this library.
|
|
Because `std::chrono::system_clock::time_point` is a __time point__,
|
|
not capable of representing a Local Time independent from a specific day.
|
|
|
|
It is recommended to get `Datetime`s as `std::chrono` classes through `toml::get`.
|
|
|
|
## Running Tests
|
|
|
|
To run test codes, you need to clone toml-lang/toml repository under `build/` directory
|
|
because some of the test codes read a file in the repository.
|
|
|
|
```sh
|
|
$ mkdir build
|
|
$ cd build
|
|
$ git clone https://github.com/toml-lang/toml.git
|
|
$ cmake ..
|
|
$ make
|
|
$ make test
|
|
```
|
|
|
|
To run the language agnostic test suite, you need to compile
|
|
`tests/check_toml_test.cpp` and pass it to the tester.
|
|
|
|
## Contributors
|
|
|
|
I appreciate the help of the contributors who introduced the great feature to this library.
|
|
|
|
- Guillaume Fraux (@Luthaf)
|
|
- Windows support and CI on Appvayor
|
|
- Intel Compiler support
|
|
- Quentin Khan (@xaxousis)
|
|
- Found & Fixed a bug around ODR
|
|
- Improved error messages for invaild keys to show the location where the parser fails
|
|
- Petr Beneš (@wbenny)
|
|
- Fixed warnings on MSVC
|
|
- Ivan Shynkarenka (@chronoxor)
|
|
- Fixed Visual Studio 2019 warnings
|
|
- @khoitd1997
|
|
- Fixed warnings while type conversion
|
|
|
|
## Licensing terms
|
|
|
|
This product is licensed under the terms of the [MIT License](LICENSE).
|
|
|
|
- Copyright (c) 2017-2019 Toru Niina
|
|
|
|
All rights reserved.
|