Extract a RST changelog from a HG repo

changelog.py

#!/usr/bin/env python

"""
Use a mercurial repository to generate a reStructuredText changelog. 
"""

from datetime import datetime
from mercurial import ui, hg
from django.utils.datastructures import SortedDict

path_to_repo = "/path/to/repo/"
repo = hg.repository(ui.ui(), path_to_repo)
version_file = os.path.join(path_to_repo, "__init__.py")
version_var = "__version__"
changelog_filename = "CHANGELOG"
changelog_file = os.path.join(path_to_repo, changelog_filename)
versions = SortedDict()

for changeset in reversed(list(repo.changelog)):
    # Check if the file with the version number is in this changeset and if 
    # it is, pull it out and assign it as a variable.
    context = repo.changectx(changeset)
    files = context.files()
    new_version = False
    if version_file in files:
        for line in context[version_file].data().split("\n"):
            if line.startswith(version_var):
                exec line
                version_info = {"changes": [], "date": 
                    datetime.fromtimestamp(context.date()[0]
                    ).strftime("%b %d, %Y")}
                versions[globals()[version_var]] = version_info
                new_version = len(files) == 1
    # Ignore changesets that are merges, bumped the version or regenerated
    # the changelog itself
    merge = len(context.parents()) > 1
    changelog_update = changelog_filename in files and len(files) == 1
    if merge or new_version or changelog_update:
        continue
    # Ensure we have a current version and if so, add this changeset's 
    # description to it.
    try:
        version = globals()[version_var]
    except KeyError:
        continue
    else:
        description = context.description().rstrip(".")
        user = context.user().split()[0]
        entry = "%s - %s" % (description, user)
        if entry not in versions[version]["changes"]:
            versions[version]["changes"].insert(0, entry)

# Write out the changelog.
with open(changelog_file, "w") as f:
    for version, version_info in versions.items():
        version_header = "Version %s (%s)" % (version, version_info["date"])
        f.write("%s\n" % version_header)
        f.write("%s\n" % ("-" * len(version_header)))
        f.write("\n")
        if version_info["changes"]:
            for change in version_info["changes"]:
                f.write("  * %s\n" % change)
        else:
            f.write("  * No changes listed.\n")
        f.write("\n")