doc/docchecker

releasenotes: command to manage release notes files

Per discussion on the mailing list, we want better release notes
for Mercurial.

This patch introduces an extension that provides a command for
producing release notes files. Functionality is implemented
as an extension because it could be useful outside of the
Mercurial project and because there is some code (like rst
parsing) that already exists in Mercurial and it doesn't make
sense to reinvent the wheel.

The general idea with the extension is that changeset authors
declare release notes in commit messages using rst directives.
Periodically (such as at publishing or release time), a project
maintainer runs `hg releasenotes` to extract release notes
fragments from commit messages and format them to an auto-generated
release notes file. More details are explained inline in docstrings.

There are several things that need addressed before this is ready
for prime time:

* Moar tests
* Interactive merge mode
* Implement similarity detection for individual notes items
* Support customizing section names/titles
* Parsing improvements for bullet lists and paragraphs
* Document which rst primitives can be parsed
* Retain arbitrary content (e.g. header section/paragraphs)
  from existing release notes file
* Better error messages (line numbers, hints, etc)

#!/usr/bin/env python
#
# docchecker - look for problematic markup
#
# Copyright 2016 timeless <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import, print_function

import re
import sys

leadingline = re.compile(r'(^\s*)(\S.*)$')

checks = [
  (r""":hg:`[^`]*'[^`]*`""",
    """warning: please avoid nesting ' in :hg:`...`"""),
  (r'\w:hg:`',
    'warning: please have a space before :hg:'),
  (r"""(?:[^a-z][^'.])hg ([^,;"`]*'(?!hg)){2}""",
    '''warning: please use " instead of ' for hg ... "..."'''),
]

def check(line):
    messages = []
    for match, msg in checks:
        if re.search(match, line):
            messages.append(msg)
    if messages:
        print(line)
        for msg in messages:
            print(msg)

def work(file):
    (llead, lline) = ('', '')

    for line in file:
        # this section unwraps lines
        match = leadingline.match(line)
        if not match:
            check(lline)
            (llead, lline) = ('', '')
            continue

        lead, line = match.group(1), match.group(2)
        if (lead == llead):
            if (lline != ''):
                lline += ' ' + line
            else:
                lline = line
        else:
            check(lline)
            (llead, lline) = (lead, line)
    check(lline)

def main():
    for f in sys.argv[1:]:
        try:
            with open(f) as file:
                work(file)
        except BaseException as e:
            print("failed to process %s: %s" % (f, e))

main()