mwparserfromhell 0.3

Installation

The easiest way to install the parser is through the Python Package Index, so you can install the latest release with pip install mwparserfromhell (get pip). Alternatively, get the latest development version:

git clone https://github.com/earwig/mwparserfromhell.git
cd mwparserfromhell
python setup.py install

If you get error: Unable to find vcvarsall.bat while installing, this is because Windows can’t find the compiler for C extensions. Consult this StackOverflow question for help. You can also set ext_modules in setup.py to an empty list to prevent the extension from building.

You can run the comprehensive unit testing suite with python setup.py test -q.

Usage

Normal usage is rather straightforward (where text is page text):

>>> import mwparserfromhell
>>> wikicode = mwparserfromhell.parse(text)

wikicode is a mwparserfromhell.Wikicode object, which acts like an ordinary unicode object (or str in Python 3) with some extra methods. For example:

>>> text = "I has a template! {{foo|bar|baz|eggs=spam}} See it?"
>>> wikicode = mwparserfromhell.parse(text)
>>> print wikicode
I has a template! {{foo|bar|baz|eggs=spam}} See it?
>>> templates = wikicode.filter_templates()
>>> print templates
['{{foo|bar|baz|eggs=spam}}']
>>> template = templates[0]
>>> print template.name
foo
>>> print template.params
['bar', 'baz', 'eggs=spam']
>>> print template.get(1).value
bar
>>> print template.get("eggs").value
spam

Since nodes can contain other nodes, getting nested templates is trivial:

>>> text = "{{foo|{{bar}}={{baz|{{spam}}}}}}"
>>> mwparserfromhell.parse(text).filter_templates()
['{{foo|{{bar}}={{baz|{{spam}}}}}}', '{{bar}}', '{{baz|{{spam}}}}', '{{spam}}']

You can also pass recursive=False to filter_templates() and explore templates manually. This is possible because nodes can contain additional Wikicode objects:

>>> code = mwparserfromhell.parse("{{foo|this {{includes a|template}}}}")
>>> print code.filter_templates(recursive=False)
['{{foo|this {{includes a|template}}}}']
>>> foo = code.filter_templates(recursive=False)[0]
>>> print foo.get(1).value
this {{includes a|template}}
>>> print foo.get(1).value.filter_templates()[0]
{{includes a|template}}
>>> print foo.get(1).value.filter_templates()[0].get(1).value
template

Templates can be easily modified to add, remove, or alter params. Wikicode objects can be treated like lists, with append(), insert(), remove(), replace(), and more. They also have a matches() method for comparing page or template names, which takes care of capitalization and whitespace:

>>> text = "{{cleanup}} '''Foo''' is a [[bar]]. {{uncategorized}}"
>>> code = mwparserfromhell.parse(text)
>>> for template in code.filter_templates():
...     if template.name.matches("Cleanup") and not template.has("date"):
...         template.add("date", "July 2012")
...
>>> print code
{{cleanup|date=July 2012}} '''Foo''' is a [[bar]]. {{uncategorized}}
>>> code.replace("{{uncategorized}}", "{{bar-stub}}")
>>> print code
{{cleanup|date=July 2012}} '''Foo''' is a [[bar]]. {{bar-stub}}
>>> print code.filter_templates()
['{{cleanup|date=July 2012}}', '{{bar-stub}}']

You can then convert code back into a regular unicode object (for saving the page!) by calling unicode() on it:

>>> text = unicode(code)
>>> print text
{{cleanup|date=July 2012}} '''Foo''' is a [[bar]]. {{bar-stub}}
>>> text == code
True

Likewise, use str(code) in Python 3.

Integration

mwparserfromhell is used by and originally developed for EarwigBot; Page objects have a parse method that essentially calls mwparserfromhell.parse() on page.get().

If you’re using Pywikipedia, your code might look like this:

import mwparserfromhell
import wikipedia as pywikibot
def parse(title):
    site = pywikibot.getSite()
    page = pywikibot.Page(site, title)
    text = page.get()
    return mwparserfromhell.parse(text)

If you’re not using a library, you can parse templates in any page using the following code (via the API):

import json
import urllib
import mwparserfromhell
API_URL = "http://en.wikipedia.org/w/api.php"
def parse(title):
    data = {"action": "query", "prop": "revisions", "rvlimit": 1,
            "rvprop": "content", "format": "json", "titles": title}
    raw = urllib.urlopen(API_URL, urllib.urlencode(data)).read()
    res = json.loads(raw)
    text = res["query"]["pages"].values()[0]["revisions"][0]["*"]
    return mwparserfromhell.parse(text)