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Incremental JSON parser

Project description

====== What is jsaone? ======

This is a tiny wrapper around the json module in the Python standard library, allowing to read a json file incrementally.

This can be useful for
* parsing json streams without waiting for the end of the transmission,
* parsing very big json objects without wasting RAM for the json representation itself.

It is an alternative to [[https://pypi.python.org/pypi/ijson/|ijson]] (written when I did not know ijson existed, but in the end more efficient).

=== Efficiency ===

No extensive tests were made (if you make them, let me know), but here are the
results (in seconds) obtained in opening a local file with 384650 objects,
totalling 174 MB:

^ Parser ^ Iteration 1 ^ Iteration 2 ^
| standard (non-incremental) json | 9.511 | 9.273 |
| cythonized jsaone | 19.055 | 18.956 |
| ijson (with yajl2 backend) | 62.250 | 64.538 |
| pure python jsaone | 421.641 | 421.821 |


Those results were obtained with the script "**tests/json_load_test.py**".

Clearly those numbers are affected by the speed of the CPU and of the medium/stream.
In particular, since the test was made on a file from a local hard disk, the
bottleneck was clearly the CPU, and hence it is disadvantageous for incremental
parsers (including jsaone). If the bottleneck is given by the medium/stream,
jsaone should even outperform the standard json, which will start processing
only after the entire stream is received.

=== Why "jsaone" ===

Because it sounds similar to "json"... but the Saône is a (large) stream.

=== Dependencies ===


* [[http://pypi.python.org/pypi/simplejson/|simplejson]] (Python 2.5 only)
* for speedup: [[http://cython.org|cython]] (at build time)

=== Installing ===

- If you use Debian or a derivative (such as Ubuntu or Mint), you can simply use the packages provided above.
- **jsaone** is on pypi, so you can install it with //pip install jsaone//
- you can extract/clone the git repo, then move in the "jsaone" folder and give the command

python3 setup.py build_ext --inplace

(replace "**python3**" with "**python**" if you are using Python 2).


=== Usage ===


import jsaone
with open('/path/to/my/file.json') as f:
gen = jsaone.load(f)
for key, val in gen:
...

=== Development ===

You can browse the git repo [[http://www.pietrobattiston.it/gitweb?p=jsaone.git|here]] or clone with
git clone git://pietrobattiston.it/jsaone

For bugs and enhancements, just write me - <me@pietrobattiston.it> - ideally pointing to a git branch solving the issue/providing an enhancement.

Jsaone should be able to parse any compliant json string... so if you find one on which it fails, please let me know!

=== License ===

Released under the GPL 3. Feel free to contact me if this is a problem for you (and GPL 2 is not).

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