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https://github.com/bodguy/tinyjson
Blazing fast header only json parser written in C++
https://github.com/bodguy/tinyjson
Last synced: 12 days ago
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Blazing fast header only json parser written in C++
- Host: GitHub
- URL: https://github.com/bodguy/tinyjson
- Owner: bodguy
- License: apache-2.0
- Created: 2019-11-18T04:00:10.000Z (almost 5 years ago)
- Default Branch: master
- Last Pushed: 2020-03-20T00:04:08.000Z (over 4 years ago)
- Last Synced: 2024-08-02T05:12:07.181Z (3 months ago)
- Language: C++
- Homepage:
- Size: 149 KB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
Awesome Lists containing this project
- awesome-blazingly-fast - tinyjson - Blazing fast header only json parser using C++ (C++)
README
[](https://ci.appveyor.com/project/bodguy/tinyjson)
[](https://travis-ci.com/bodguy/tinyjson)
[](https://coveralls.io/github/bodguy/tinyjson?branch=master)
# tinyjson
Blazing fast header only json parser
## Compiler
compiled and tested on c++14 or higher version.
## One Minute guide
```c++
tinyjson::json_node node;
std::string err;
string json = R"({"key":"value","obj":{"name":"hello"},"array":[32,99,75]})";
bool result = tinyjson::json_parser::parse(node, json, err);
if (!result) {
std::cout << err << std::endl;
return -1;
}
// true -> prettify serialize
// false -> unformatted serialize (default)
std::cout << node.serialize(true) << std::endl;
```
```json
{
"key": "value",
"obj": {
"name": "hello"
},
"array": [
32,
99,
75
]
}
```
## Tutorial
In [RFC 4627](https://tools.ietf.org/html/rfc4627), only objects or arrays were allowed as root values of json.
```c++
assert(node.is_object());
assert(node.is_array());
```
## Get the values
Let's query about "key1" is exists or not.
```c++
assert(node.has("key1"));
assert(node["key1"].is_object());
std::cout << node["key1"].serialize(true) << std::endl;
```
```json
{
"hello": true,
"hello2": false,
"hello3": null,
"hello4": [
1,
1.33,
99.8,
21.92
]
}
```
[] based approach is convenient like accessing plain javascript object.
below code shows function based approach equivalent which is a bit messy.
```c++
std::cout << node.get_node("key1").serialize(true) << std::endl;
```
## Set the values
setting values are simple as getting values. just take a value from [] operator and assign other values to this.
```c++
object root;
root.insert(std::make_pair("key", new json_node("value")));
node["key1"]["hello4"] = root;
std::cout << node.serialize(true) << std::endl;
```
```json
{
"hello": true,
"hello2": false,
"hello3": null,
"hello4": {
"key": "value"
}
}
```
as you know, assigning is also work with number, array, object, boolean and string.
```c++
node["key1"]["hello4"] = "hello world";
node["key1"]["hello3"] = 10.22;
std::cout << node.serialize(true) << std::endl;
```
```json
{
"hello": true,
"hello2": false,
"hello3": 10.22,
"hello4": "hello world"
}
```
but beware that, assigning null json value should be as follows.
```c++
node["key1"]["hello"] = json_node();
```
```
"hello": null
```
beacuse empty json_node is same as null json value.
you can assign a json_node directly.
```c++
object root;
root.insert(std::make_pair("key", new json_node("value")));
object inner;
inner.insert(std::make_pair("name", new json_node("hello")));
root.insert(std::make_pair("obj", new json_node(inner)));
auto* arr = new json_node({new json_node(32.0), new json_node(99.0), new json_node(75.0)});
root.insert(std::make_pair("array", arr));
json_node node2(root);
node["key1"]["hello4"] = node2;
```
```json
{
"key1": {
"hello": true,
"hello2": false,
"hello3": null,
"hello4": {
"key": "value",
"obj": {
"name": "hello"
},
"array": [
32,
99,
75
]
}
}
}
```
there are another case assigning same json_node instance. this will cause a undefined behaviour like memory leak.
## Query array
what about array? below sample code shows how to loop through all the elements.
but beware that, json_node.length() function works with string, array and object as well.
so make sure json_node is array type before looping array elements.
```c++
tinyjson::json_node& array_node = node["key1"]["hello4"];
assert(array_node.is_array());
for (size_t i = 0; i < array_node.length(); ++i) {
std::cout << "hello4[" << i << "]: " << array_node[i].get_number() << std::endl;
}
```
```
hello4[0]: 1
hello4[1]: 1.33
hello4[2]: 99.8
hello4[3]: 21.92
```
or, using c++11 range based loop.
note that, array is just a stl vector container. you can use standard iterator as you know.
```c++
tinyjson::json_node& array_node = node["key1"]["hello4"];
assert(array_node.is_array());
tinyjson::array& arr = array_node.get_array();
int i = 0;
for (auto n : arr) {
std::cout << "hello4[" << i << "]: " << n->get_number() << std::endl;
i++;
}
```
```
hello4[0]: 1
hello4[1]: 1.33
hello4[2]: 99.8
hello4[3]: 21.92
```
## Query object
querying object is same as array.
note that, object is almost same as ordered map. so any kind of standard iterator can be used.
```c++
tinyjson::object& obj_node = node["key1"].get_object();
for (auto& v : obj_node) {
std::cout << v.second.serialize(true) << std::endl;
}
```
```
true
false
null
[
1,
1.33,
99.8,
21.92
]
```
## Compare values
comparing values are simple like string compare.
```c++
assert(node == node2);
json_node& first = node.get_node("key1").get_node("hello4").get_element(3);
// OR node["key1"]["hello4"][3];
assert(first == 21.92);
```
there are four kind of operators:
```c++
inline bool operator==(const json_node& other);
inline bool operator==(const string& other);
inline bool operator==(const double other);
inline bool operator==(const int other);
```
operator with json_node compare two json_node as deep equal. the other three operator compare with json_node inner value.
## Export to json
export to json is a bit complex now.
```c++
object root;
root.insert(std::make_pair("key", new json_node("value")));
object inner;
inner.insert(std::make_pair("name", new json_node("hello")));
root.insert(std::make_pair("obj", new json_node(inner)));
auto* arr = new json_node({new json_node(32.0), new json_node(99.0), new json_node(75.0)});
root.insert(std::make_pair("array", arr));
json_node node2(root);
std::cout << node2.serialize(true) << std::endl; // prettify print
```
```json
{
"key": "value",
"obj": {
"name": "hello"
},
"array": [
32,
99,
75
]
}
```
## Number
The number is represented by e-notation.
```json
{
"e-not": 3.125e7
}
```
above example can be expressed as following.
```json
{
"e-not": 31250000
}
```
## Performance benchmark
tested on MackBook Pro 2.5Ghz Quad core i7, 16GB RAM
with json file which has about 190 MB size.
clang version 9.0.1:
```
deserialize: 3762.73 ms
serialize: 3805.3 ms
```
msvc 16:
```
deserialize: 4891.86 ms
serialize: 5942.79 ms
```
## Macro
- USE_UNICODE: determines which one use from u16string and u8string.
## TODO
- utf8 support: switching to utf16string