Find header character sets used in a list of RST files

header_chars.py

#!/usr/bin/env python
"""
Find the sets of characters used in RST section headers.  For input like
::

  ##########
  header
  ##########

  Section
  ========

  Subsection
  -----------

  Section 2
  ==========

then the get_header_chars() routine will return '#=-'.  It also checks that the
ordering is valid.

Usage::

  % find . -name "*.rst" | xargs ./header_chars.py
  ...  # bunch of files and their section orderings
  #*=
  *=-"
  *=-^"
  -^".
  -^">
  =-^"
  =-`

  % find . -name "*.rst" | xargs ./header_chars.py | grep '=-`'
  ./wcs/history.rst =-`
  =-`

"""

import sys


def get_header_chars(filename):
    lines = (x.strip() for x in open(filename, 'r'))
    header_chars = ''
    level = -1
    for line in lines:
        line_len = len(line)
        if line_len == 0:
            continue
        char = line[0]
        if line == char * line_len and line_len > 2:
            if char not in header_chars:
                if level == len(header_chars) - 1:
                    header_chars += char
                    level += 1
                else:
                    raise ValueError('ERROR misorder {} at level {} from {}'
                                     .format(char, level, header_chars))
            else:
                new_level = header_chars.index(char)
                if new_level > level + 1:
                    raise ValueError('ERROR misorder new_level={} level={} '
                                     'char={} header_chars={}'
                                     .format(new_level, level, char,
                                             header_chars))
                else:
                    level = new_level

    return header_chars


def main():
    header_chars_set = set()
    filenames = sys.argv[1:]
    for filename in filenames:
        print filename,
        try:
            header_chars = get_header_chars(filename)
            header_chars_set.add(header_chars)
            print header_chars
        except ValueError as err:
            print err

    header_chars_list = sorted(header_chars_set)
    all_header_chars = []
    for hc0, hc1 in zip(header_chars_list[:-1], header_chars_list[1:]):
        if not hc1.startswith(hc0):
            all_header_chars.append(hc0)
    all_header_chars.append(hc1)

    print '\n'.join(all_header_chars)


if __name__ == '__main__':
    main()