crjson
crjson is an iterative JSON parser using Python couroutines interface.
It is a fork from Ivan Sagalaev <https://github.com/isagalaev> library that justs rethinks the
flow from a generator library to a coroutine library.
The main point of it is to allowing better integration with long results
Usage

All usage example will be using a JSON document describing geographical objects:

{
  "earth": {
    "europe": [
      {"name": "Paris", "type": "city", "info": { ... }},
      {"name": "Thames", "type": "river", "info": { ... }},
      // ...
    ],
    "america": [
      {"name": "Texas", "type": "state", "info": { ... }},
      // ...
    ]
  }
}

Most common usage is having crjson yield native Python objects out of a JSON stream located under a prefix. Here's how to process all European cities:

import crjson
import contextlib

@crjson.utils.coroutine
def sink(rs):
    try:
        while True:
            data = (yield)
            rs.append(data)
    except GeneratorExit:
        pass

def reader(fp, target):
    while True:
        data = fp.read()
        if not data:
            break
        target.send(data)

objects = []

from io import BytesIO
f = BytesIO(b'''    {
          "earth": {
            "europe": [
        {"name": "Paris", "type": "city", "info": { "more": 1}},
        {"name": "Thames", "type": "river", "info": { "more": 2}}
            ],
            "america": [
        {"name": "Texas", "type": "state", "info": { "more": 3}}
            ]
          }
        }
    ''')

with contextlib.closing(sink(objects)) as sink_cr:
    with contextlib.closing(crjson.items('earth.europe.item', sink_cr)) as parser:
        reader(f, parser)

cities = (o for o in objects if o['type'] == 'city')
for city in cities:
    print city

Backends

Ijson provides several implementations of the actual parsing in the form of backends located in crjson/backends:

• yajl2: wrapper around YAJL version 2.x
• yajl: wrapper around YAJL version 1.x

You can import a specific backend and use it in the same way as the top level library:

import crjson.backends.yajl as crjson

for item in crjson.items(...):
    # ...

Importing the top level library as import crjson tries to import all backends in order, so it either finds an appropriate version of YAJL.

Acknowledgements

Python parser in crjson is relatively simple thanks to Douglas Crockford who invented a strict, easy to parse syntax.

The YAJL library by Lloyd Hilaiel is the most popular and efficient way to parse JSON in an iterative fashion.

Ijson was inspired by yajl-py wrapper by Hatem Nassrat. Though ijson borrows almost nothing from the actual yajl-py code it was used as an example of integration with yajl using ctypes.