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C++解析配置文件初体验
背景
找一个C++解析配置文件的类。
初体验
代码
代码：https://github.com/marzer/tomlplusplus
示例
配置文件示例
[library]
name = "toml++"
authors = ["Mark Gillard <[email protected]>"]
[dependencies]
cpp = 17
解析
#include <toml++/toml.hpp>
auto config = toml::parse_file( "configuration.toml" );
// get key-value pairs
std::string_view library_name = config["library"]["name"].value_or(""sv);
std::string_view library_author = config["library"]["authors"][0].value_or(""sv);
int64_t depends_on_cpp_version = config["dependencies"]["cpp"].value_or(0);
// modify the data
config.insert_or_assign("alternatives", toml::array{
"cpptoml",
"toml11",
"Boost.TOML"
});
// use a visitor to iterate over heterogenous data
config.for_each([](auto& key, auto& value)
{
std::cout << value << "\n";
if constexpr (toml::is_string<decltype(value)>)
do_something_with_string_values(value);
});
// you can also iterate more 'traditionally' using a ranged-for
for (auto&& [k, v] : config)
{
// ...
}
// re-serialize as TOML
std::cout << config << "\n";
// re-serialize as JSON
std::cout << toml::json_formatter{ config } << "\n";
// re-serialize as YAML
std::cout << toml::yaml_formatter{ config } << "\n";
C++11初体验
上面那个实现是C++17的，这里用一个C++11的实现。
代码
https://github.com/ToruNiina/toml11
示例
#include <toml.hpp>
#include <iostream>
int main()
{
// ```toml
// title = "an example toml file"
// nums = [3, 1, 4, 1, 5]
// ```
auto data = toml::parse("example.toml");
// find a value with the specified type from a table
std::string title = toml::find<std::string>(data, "title");
// convert the whole array into any container automatically
std::vector<int> nums = toml::find<std::vector<int>>(data, "nums");
// access with STL-like manner
if(!data.contains("foo"))
{
data["foo"] = "bar";
}
// pass a fallback
std::string name = toml::find_or<std::string>(data, "name", "not found");
// width-dependent formatting
std::cout << std::setw(80) << data << std::endl;
return 0;
}