Little tool to filter tex(t) files

text-filter.py

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
import os


class Cleaner:
    def __init__(self, filename, *filter_actions):
        self.file = open(filename, 'r')
        self.filter_actions = filter_actions

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        self.file.close()

    def clean(self):
        for action in self.filter_actions:
            with action(self) as a:
                a.filter()


class AbstractFilterAction:
    def __init__(self, cleaner):
        self.cleaner = cleaner
        self.file = open(".%s.%s" % (self.cleaner.file.name,
                                     self.__class__.__name__),
                         'w')

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        self.file.close()
        os.rename(self.file.name, self.cleaner.file.name)

    @property
    def input_file(self):
        return self.cleaner.file

    def filter(self):
        self.cleaner.file.seek(0)
        self.file.writelines(self.action())

    def action(self):
        pass


class CleanFootnotesFilterAction(AbstractFilterAction):
    def action(self):
        lines = []
        for line in self.input_file:
            if line.startswith("\\footnote"):
                lines[-1] = "".join([lines[-1][:-1], line])
            else:
                lines.append(line.replace(" \\footnote{", "\\footnote{"))
        return lines

if __name__ == "__main__":
    import sys
    if len(sys.argv) < 2:
        print("Please provide the filename for the tex file to filter")
    with Cleaner(sys.argv[1],
                 CleanFootnotesFilterAction) as c:
        c.clean()

CleanFootnotesFilterAction is an example of an filter action -- only the action methods needs to get implemented.
Cleaner instances can be configured with FilterActions on instantiation (lines 59f).

The initial use case was to alter generated tex-files ;)