ref: fbcc8d1b0e05cace2abe2083a88a8c2304efc9d7
dir: /tools/toc.py/
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Usage: python3 toc.py [-n] files.md...
Replace a "## TOC" heading in a Markdown file with a table of contents,
generated from the other headings in the file. Supports multiple files.
Headings must start with "##" signs to be detected.
"""
import sys
import re
from collections import namedtuple
toc_name = 'Contents'
valid_toc_headings = {'## TOC', '##TOC'}
TocItem = namedtuple('TocItem', ['name', 'anchor', 'level'])
punctuation_regexp = re.compile(r'[^\w\- ]+')
specialchar_regexp = re.compile(r'[⅔]+')
def name_to_anchor(name):
# GitHub's algorithm for generating anchors from headings
# https://github.com/jch/html-pipeline/blob/master/lib/html/pipeline/toc_filter.rb
anchor = name.strip().lower() # lowercase
anchor = re.sub(punctuation_regexp, '', anchor) # remove punctuation
anchor = anchor.replace(' ', '-') # replace spaces with dash
anchor = re.sub(specialchar_regexp, '', anchor) # remove misc special chars
return anchor
def get_toc_index(lines):
toc_index = None
for i, line in enumerate(lines):
if line.rstrip() in valid_toc_headings:
toc_index = i
break
return toc_index
def get_toc_items(lines, toc_index):
for i, line in enumerate(lines):
if i <= toc_index:
continue
if line.startswith('##'):
name = line.lstrip('#')
level = len(line) - len(name) - len('##')
name = name.strip()
anchor = name_to_anchor(name)
yield TocItem(name, anchor, level)
def toc_string(toc_items):
lines = ['## %s' % toc_name, '']
for name, anchor, level in toc_items:
padding = ' ' * level
line = '%s- [%s](#%s)' % (padding, name, anchor)
lines.append(line)
return '\n'.join(lines) + '\n'
def add_toc(filename):
with open(filename, 'r', encoding='utf-8') as f:
lines = f.readlines()
toc_index = get_toc_index(lines)
if toc_index is None:
return None # no TOC heading
toc_items = list(get_toc_items(lines, toc_index))
if not toc_items:
return False # no content headings
with open(filename, 'w', encoding='utf-8') as f:
for i, line in enumerate(lines):
if i == toc_index:
f.write(toc_string(toc_items))
else:
f.write(line)
return True # OK
def main():
if len(sys.argv) < 2:
print('*** ERROR: No filenames specified')
print(__doc__)
exit(1)
for filename in sys.argv[1:]:
print(filename)
result = add_toc(filename)
if result is None:
print('*** WARNING: No "## TOC" heading found')
elif result is False:
print('*** WARNING: No content headings found')
else:
print('OK')
if __name__ == '__main__':
main()