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https://github.com/sjtufl/jfson
Light weight JSON parser and generator.
https://github.com/sjtufl/jfson
Last synced: about 2 months ago
JSON representation
Light weight JSON parser and generator.
- Host: GitHub
- URL: https://github.com/sjtufl/jfson
- Owner: sjtufl
- Created: 2018-01-25T14:09:28.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2019-03-19T13:56:51.000Z (almost 6 years ago)
- Last Synced: 2023-12-01T04:34:35.356Z (about 1 year ago)
- Language: C++
- Homepage:
- Size: 655 KB
- Stars: 1
- Watchers: 1
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
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README
# JFSON
JFSON is a light-weight JSON parser and generator, which support DOM (Document Object Model) as well as SAX (Simple API for XML) style API.
## Design
### Core Concepts
Inspired by [RapidJSON](https://github.com/Tencent/rapidjson), JFSON defines several core concepts as follows:
* `Value`
As the core concept for DOM API, `Value` is of variant type. An instance of `Value` could be any JSON data type.
* `ReadStream`
`ReadStream` is used for reading char stream as the input of JSON parser.`StringReadStream` and `FileReadStream` read chars from memory and file respectively.
* `WriteStream`
Similar to `ReadStream`, `WriteStream` outputs byte stream to memory (`StringWriteStream`) or file on disk (`FileWriteStream`).
* `Handler`
`Handler` is critical for implementing SAX API. In nature, it's an events handler when parsing JSON stream. Class `Document` and Class `Writer` are implemented `Handler` in JFSON. What's more, users can build their own `Handler` according to their needs.
### Parsing and Generating
* JFSON adopts recursive parser by default
* Support comprehensive error tips if parsing failed
* Support JSON string generation
* Reasonable memory overheads
### Miscellaneous
* Make use of some new features of modern C++.
* std::string_view
* rvalue reference
* template
* range-based loop
## Usage
### Parsing JSON
For small sized JSON string or file, we could use DOM style API. Modifying the variable in a parsed JSON object can also be done via DOM API.
```c++
int main()
{
Document doc;
ParseError err = doc.parse(R"(
{
"precision": "zip",
"Latitude": 37.766800000000003,
"Longitude": -122.3959,
"Address": "Mountain View City",
"City": "SAN FRANCISCO",
"State": "CA",
"Zip": "94107",
"Country": "US",
"Number": 0i32,
"Number2": 0i64
}
)");
if (err != PARSE_OK) {
puts(parseErrorStr(err));
exit(1);
}
JsonValue& state = doc["State"];
std::cout << "State: " << state.getStringView() << '\n';
JsonValue& zip = doc["Zip"];
std::cout << "Zip: " << zip.getStringView() << "\n";
zip.setInt32(9527);
std::cout << "Zip: " << zip.getInt32() << "\n";
doc.addMember("123", "456");
JsonValue& test = doc["Address"];
std::cout << "test: addMember: " << test.getStringView() << std::endl;
}
```
Corresponding output:
```shell
State: CA
Zip: 94107
Zip: 9527
test: addMember: Mountain View City
Process finished with exit code 0
```
### Generating JSON
We could leverage `Writer` to generate JSON string like this:
```c++
int main()
{
FileWriteStream ws(stdout);
JsonWriter writer(ws);
writer.StartArray();
writer.Bool(false);
writer.String("\0溜溜溜\0"sv);
writer.Bool(true);
writer.StartObject();
writer.Key("sjtu");
writer.String("\0蛤elder蛤\0"sv);
writer.EndObject();
writer.Int32(2048);
writer.Double(NAN);
writer.EndArray();
}
```
The corresponding output:
```shell
[false,"\u0000溜溜溜\u0000",true,{"sjtu":"\u0000蛤elder蛤\u0000"},2048,NaN]
Process finished with exit code 0
```
## References
* [JSON tutorial](https://github.com/miloyip/json-tutorial) 从零开始的JSON库教程