pyesprima 1.0.0

Python port of Esprima, the Javascript parser.

A Python port of [Esprima][1], the JavaScript parser.

Why shouldn’t I use it?

It’s pretty slow – about two orders of magnitude slower to parse a 116k JS file. The code was semi-automatically translated from JavaScript, and it does a lot of string appending, which is fast in JS but slow in Python.

Why should I use it?

Shelling out to a NodeJS process is likely to be a better way to use Esprima from Python. However, writing the interprocess data-marshaling code is a bit annoying, so if you want to do a quick hack on small amounts of data, PyEsprima is a good way to get down to business. The API is exactly the same, so you can easily swap in an interface to the external Node process later on.

Also, since the code is semi-automatically translated using [js2py][2], it’s pretty easy to keep up-to-date. You could even do it yourself. Don’t fear the bit rot!

API

Pretty much the same as Esprima’s / SpiderMonkey’s API:

>>> import pyesprima

>>> print pyesprima.tokenize("1 + 1")
[{'type': 'Numeric', 'value': '1'},
 {'type': 'Punctuator', 'value': '+'},
 {'type': 'Numeric', 'value': '1'}]

>>> pyesprima.parse("1 + 1", loc=True)
{'body': [{'type': 'ExpressionStatement', 'expression': {'operator': '+',
'loc': {'start': {'column': 0, 'line': 1}, 'end': ...

Installing

pip install pyesprima

[1]: http://esprima.org/ [2]: https://github.com/int3/js2py