现代化的全平台 Json/Json5 解析/生成器，Header-only，并附带大量语法糖！
A modern all-platform Json/Json5 parser/serializer, which is header-only and contains lots of syntactic sugar!
- 在您的项目中包含头文件即可使用
#include "json.hpp"- 若您需要解析 Json5, 则请包含
json5.hpp头文件
#include "json5.hpp"- meojson 仅依赖 STL, 但需要 c++17 标准
/***
* from sample/sample.cpp
***/
#include <iostream>
#include "json.hpp"
void parsing()
{
std::string content = R"(
{
"repo": "meojson",
"author": {
"MistEO": "https://github.com/MistEO",
"ChingCdesu": "https://github.com/ChingCdesu"
},
"list": [ 1, 2, 3 ],
"str": "abc\n123",
"num": 3.1416,
"A_obj": {
"B_arr": [
{ "C_str": "i am a distraction" },
{ "C_str": "you found me!" }
]
}
}
)";
auto ret = json::parse(content);
if (!ret) {
std::cerr << "Parsing failed" << std::endl;
return;
}
auto& value = ret.value(); // you can use rvalues if needed, like
// `auto value = std::move(ret).value();`
// Output: meojson
std::cout << value["repo"].as_string() << std::endl;
/* Output:
ChingCdesu's homepage: https://github.com/ChingCdesu
MistEO's homepage: https://github.com/MistEO
*/
for (auto&& [name, homepage] : value["author"].as_object()) {
std::cout << name << "'s homepage: " << homepage.as_string() << std::endl;
}
// Output: abc
std::string str = (std::string)value["str"]; // it is equivalent to `value["str"].as_string()`
std::cout << str << std::endl;
// Output: 3.141600
double num = value["num"].as_double(); // similarly, you can use `(double)value["num"]`
std::cout << num << std::endl;
// Output: default_value
std::string get = value.get("maybe_exists", "default_value");
std::cout << get << std::endl;
// Output: you found me!
std::string nested_get = value.get("A_obj", "B_arr", 1, "C_str", "default_value");
std::cout << nested_get << std::endl;
// Output: 1, 2, 3
// If the "list" is not an array or not exists, it will be a invalid optional;
auto opt = value.find<json::array>("list");
if (opt) {
auto& arr = opt.value();
for (auto&& elem : arr) {
std::cout << elem.as_integer() << std::endl;
}
}
// more examples, it will output 3.141600
auto opt_n = value.find<double>("num");
if (opt_n) {
std::cout << opt_n.value() << std::endl;
}
// If you use the `find` without template argument, it will return a `std::optional<json::value>`
auto opt_v = value.find("not_exists");
std::cout << "Did we find the \"not_exists\"? " << opt_v.has_value() << std::endl;
std::vector<int> to_vec = value["list"].to_vector<int>();
std::list<int> to_list = value["list"].to_vector<int, std::list>();
std::set<int> to_set = value["list"].to_vector<int, std::set>();
// Output: 1, 2, 3
for (auto&& i : to_vec) {
std::cout << i << std::endl;
}
std::map<std::string, std::string> to_map = value["author"].to_map<std::string>();
auto to_hashmap = value["author"].to_map<std::string, std::unordered_map>();
// Output: "literals"
using namespace json::literals;
auto val = "{\"hi\":\"literals\"}"_json;
std::cout << val["hi"] << std::endl;
}/***
* from sample/json5_parse.cpp
***/
#include <iostream>
#include "json5.hpp"
void parsing()
{
std::string_view content = R"(
// 这是一段json5格式的信息
{
名字: "MistEO", /* key的引号可省略 */
😊: '😄', // emoji为key
thanks: 'ありがとう', /* 单引号也可以表示字符串 */
\u006Bey: ['value',], // 普通字符和转义可以混用
inf: +Infinity, nan: NaN, // 数字可以以"+"开头
fractional: .3, integer: 42., // 小数点作为起始/结尾
byte_max: 0xff, // 十六进制数
light_speed: +3e8, // 科学计数法
}
)";
auto ret = json::parse5(content);
if (!ret) {
std::cerr << "Parsing failed" << std::endl;
return;
}
auto& value = ret.value(); // you can use rvalues if needed, like
// `auto value = std::move(ret).value();`
// Output: MistEO
std::cout << value["名字"] << std::endl;
// Output: value
std::string str = (std::string)value["key"][0];
std::cout << str << std::endl;
// for more json::value usage, please refer to sample.cpp
}/***
* from sample/sample.cpp
***/
#include <iostream>
#include "json.hpp"
void serializing()
{
json::value root;
root["hello"] = "meojson";
root["Pi"] = 3.1416;
root["obj"] = {
{ "obj_key1", "Hi" },
{ "obj_key2", 123 },
{ "obj_key3", true },
};
root["obj"].emplace("obj_key4", 789);
root["obj"].emplace("obj_key5", json::object { { "key4 child", "i am object value" } });
root["another_obj"]["child"]["grand"] = "i am grand";
// take union
root["obj"] |= json::object {
{ "obj_key6", "i am string" },
{ "obj_key7", json::array { "i", "am", "array" } },
};
root["arr"] = json::array { 1, 2, 3 };
root["arr"].emplace(4);
root["arr"].emplace(5);
root["arr"] += json::array { 6, 7 };
std::vector<int> vec = { 1, 2, 3, 4, 5 };
root["arr from vec"] = vec;
std::set<std::string> set = { "a", "bb\n\nb", "cc\t" };
root["arr from set"] = set;
std::map<std::string, int> map {
{ "key1", 1 },
{ "key2", 2 },
};
root["obj from map"] = map;
std::vector<std::list<std::set<int>>> complex { { { 1, 2, 3 }, { 4, 5 } }, { { 6 }, { 7, 8 } } };
root["complex"] = json::serialize<false>(complex);
std::map<std::string, std::map<int, std::vector<double>>> more_complex {
{ "key1", { { 1, { 0.1, 0.2 } }, { 2, { 0.2, 0.3 } } } },
{ "key2", { { 3, { 0.4 } }, { 4, { 0.5, 0.6, 0.7 } } } },
};
// the "std::map<int, xxx>" cannot be converted to json because the key is "int",
// you can set the template parameter "loose" of "serialize" to true, which will make a more relaxed conversion.
root["more_complex"] = json::serialize<true>(more_complex);
std::cout << root << std::endl;
std::ofstream ofs("meo.json");
ofs << root;
ofs.close();
}