A JSON parser in C++
Introduction
JSON++ is a light-weight JSON parser, writer and reader written in C++. JSON++ can also convert JSON documents into lossless XML documents.
Contributors
If you've made substantial contribution, please add your link here.
Why another JSON parser?
Perhaps because web service clients are usually written in dynamic languages these days, none of the existing C++ JSON parsers fitted my needs very well, so I wrote one that I used in another project. My goals for JSON++ were:
- Efficient in both memory and speed.
- No third party dependencies. JSON++ only depends on the standard C++ library.
- Cross platform.
- Robust.
- Small and convenient API. Most of the time, you only need to call one function and two function templates.
- Easy to integrate. JSON++ only has one source file and one header file. Just compile the source file and link with your program.
- Able to construct documents dynamically.
- JSON writer: write documents in JSON format.
Other contributors have sinced added more functionalities:
- XML writer: convert documents to JSONx format. See http://goo.gl/I3cxs for details.
- XML writer: convert documents to JXML format. See https://github.com/r-lyeh/JXML for details.
- XML writer: convert documents to JXMLex format. See https://github.com/r-lyeh/JXMLex for details.
- XML writer: convert documents to tagged XML format. See https://github.com/hjiang/jsonxx/issues/12 for details.
Compiler version
You need a modern C++ compiler. For older compilers, please try legacy branch.
Configuration
Strict/permissive parsing
JSONxx can parse JSON documents both in strict or permissive mode.
When jsonxx::Settings::Parser
is set to Strict
, JSONxx parser will accept:
- Fully conformant JSON documents only.
When jsonxx::Settings::Parser
is set to Permissive
, JSONxx parser will accept:
- Fully conformant JSON documents
- Ending commas in arrays and objects:
{ "array": [0,1,2,], }
- Single quoted strings:
['hello', "world"]
- C++ style comments:
{ "width": 320, "height": 240 } //Picture details
Default value is Permissive
.
When jsonxx::Settings::UnquotedKeys
is set to Enabled
, JSONxx parser will accept:
- Unquoted keys:
{name: "world"}
Default value is Disabled
.
Assertions
JSONxx uses internally JSONXX_ASSERT(...)
macro that works both in debug and release mode. Set jsonxx::Settings::Assertions
value to Disabled
to disable assertions.
Default value is Enabled
.
Usage
The following snippets are from one of the unit tests. They are quite self-descriptive.
using namespace std;
using namespace jsonxx;
string teststr(
"{"
" \"foo\" : 1,"
" \"bar\" : false,"
" \"person\" : {\"name\" : \"GWB\", \"age\" : 60,},"
" \"data\": [\"abcd\", 42],"
"}"
);
// Parse string or stream
Object o;
assert(o.parse(teststr));
// Validation. Checking for JSON types and values as well
assert(1 == o.get<Number>("foo"));
assert(o.has<Boolean>("bar"));
assert(o.has<Object>("person"));
assert(o.get<Object>("person").has<Number>("age"));
assert(!o.get<Object>("person").has<Boolean>("old"));
assert(o.get<Object>("person").get<Boolean>("old", false));
assert(o.has<Array>("data"));
assert(o.get<Array>("data").get<Number>(1) == 42);
assert(o.get<Array>("data").get<String>(0) == "abcd");
assert(o.get<Array>("data").get<String>(2, "hello") == "hello");
assert(!o.has<Number>("data"));
cout << o.json() << endl; // JSON output
cout << o.xml(JSONx) << endl; // JSON to XML conversion (JSONx subtype)
cout << o.xml(JXML) << endl; // JSON to XML conversion (JXML subtype)
cout << o.xml(JXMLex) << endl; // JSON to XML conversion (JXMLex subtype)
// Generate JSON document dynamically
using namespace std;
using namespace jsonxx;
Array a;
a << 123;
a << "hello world";
a << 3.1415;
a << 99.95f;
a << 'h';
a << Object("key", "value");
Object o;
o << "key1" << "value";
o << "key2" << 123;
o << "key3" << a;
cout << o.json() << endl;
To do
- Custom JSON comments (C style /**/) when permissive parsing is enabled.
license | MIT |
---|---|
project | jsonxx |
url | github.com/hjiang/jsonxx |
hong@hjiang.net |
version | 1.0.1+1 |
---|---|
repository | https://pkg.cppget.org/1/stable |
depends | 0 |
reviews | +1 |