--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/changelog/category_title.rst	Fri Jul 31 23:35:07 2015 -0700
@@ -0,0 +1,4 @@
+
+1.%sub_num% %category%
+----------------------
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/changelog/header.rst	Fri Jul 31 23:35:07 2015 -0700
@@ -0,0 +1,10 @@
+
+#########
+CHANGELOG
+#########
+
+This is the changelog for PieCrust_.
+
+.. _PieCrust: http://bolt80.com/piecrust/
+
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/changelog/version_title.rst	Fri Jul 31 23:35:07 2015 -0700
@@ -0,0 +1,5 @@
+
+==================================
+%num%. PieCrust %version% (%date%)
+==================================
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/generate_changelog.py	Fri Jul 31 23:35:07 2015 -0700
@@ -0,0 +1,161 @@
+import os
+import os.path
+import re
+import sys
+import subprocess
+
+
+hg_log_template = ("{if(tags, '>>{tags};{date|shortdate}\n')}"
+                   "{desc|firstline}\n\n")
+
+re_add_tag_changeset = re.compile('^Added tag [^\s]+ for changeset [\w\d]+$')
+re_merge_pr_changeset = re.compile('^Merge pull request')
+re_tag = re.compile('^\d+\.\d+\.\d+([ab]\d+)?(rc\d+)?$')
+re_change = re.compile('^(\w+):')
+re_clean_code_span = re.compile('([^\s])``([^\s]+)')
+
+category_commands = [
+        'chef', 'bake', 'find', 'help', 'import', 'init', 'paths', 'plugin',
+        'plugins', 'prepare', 'purge', 'root', 'routes', 'serve',
+        'showconfig', 'showrecord', 'sources', 'theme', 'themes']
+category_core = [
+        'internal', 'bug', 'templating', 'formatting', 'performance',
+        'data', 'config', 'rendering', 'render', 'debug', 'reporting',
+        'linker', 'pagination', 'routing', 'caching']
+category_project = ['build', 'cm', 'docs', 'tests', 'setup']
+categories = [
+        ('commands', category_commands),
+        ('core', category_core),
+        ('project', category_project),
+        ('miscellaneous', None)]
+category_names = list(map(lambda i: i[0], categories))
+
+
+def generate():
+    out_file = 'CHANGELOG.rst'
+    if len(sys.argv) > 1:
+        out_file = sys.argv[1]
+
+    print("Generating %s" % out_file)
+
+    if not os.path.exists('.hg'):
+        raise Exception("You must run this script from the root of a "
+                        "Mercurial clone of the PieCrust repository.")
+    hglog = subprocess.check_output([
+        'hg', 'log',
+        '--rev', 'reverse(::master)',
+        '--template', hg_log_template])
+    hglog = hglog.decode('utf8')
+
+    templates = _get_templates()
+
+    with open(out_file, 'w') as fp:
+        fp.write(templates['header'])
+
+        skip = False
+        in_desc = False
+        current_version = 0
+        current_version_info = None
+        current_changes = None
+        for line in hglog.splitlines():
+            if line == '':
+                skip = False
+                in_desc = False
+                continue
+
+            if not in_desc and line.startswith('>>'):
+                tags, tag_date = line[2:].split(';')
+                if re_tag.match(tags):
+                    if current_version > 0:
+                        _write_version_changes(
+                                templates,
+                                current_version, current_version_info,
+                                current_changes, fp)
+
+                    current_version += 1
+                    current_version_info = tags, tag_date
+                    current_changes = {}
+                    in_desc = True
+                else:
+                    skip = True
+                continue
+
+            if skip or current_version == 0:
+                continue
+
+            if re_add_tag_changeset.match(line):
+                continue
+            if re_merge_pr_changeset.match(line):
+                continue
+
+            m = re_change.match(line)
+            if m:
+                ch_type = m.group(1)
+                for cat_name, ch_types in categories:
+                    if ch_types is None or ch_type in ch_types:
+                        msgs = current_changes.setdefault(cat_name, [])
+                        msgs.append(line)
+                        break
+                else:
+                    assert False, ("Change '%s' should have gone in the "
+                                   "misc. bucket." % line)
+            else:
+                msgs = current_changes.setdefault('miscellaneous', [])
+                msgs.append(line)
+
+        if current_version > 0:
+            _write_version_changes(
+                    templates,
+                    current_version, current_version_info,
+                    current_changes, fp)
+
+
+def _write_version_changes(templates, version, version_info, changes, fp):
+    tokens = {
+            'num': str(version),
+            'version': version_info[0],
+            'date': version_info[1]}
+    tpl = _multi_replace(templates['version_title'], tokens)
+    fp.write(tpl)
+
+    for i, cat_name in enumerate(category_names):
+        msgs = changes.get(cat_name)
+        if not msgs:
+            continue
+
+        tokens = {
+                'sub_num': str(i),
+                'category': cat_name.title()}
+        tpl = _multi_replace(templates['category_title'], tokens)
+        fp.write(tpl)
+
+        for msg in msgs:
+            msg = msg.replace('`', '``').rstrip('\n')
+            msg = re_clean_code_span.sub(r'\1`` \2', msg)
+            fp.write('* ' + msg + '\n')
+
+
+def _multi_replace(s, tokens):
+    for token in tokens:
+        s = s.replace('%%%s%%' % token, tokens[token])
+    return s
+
+
+def _get_templates():
+    tpl_dir = os.path.join(os.path.dirname(__file__), 'changelog')
+    tpls = {}
+    for name in os.listdir(tpl_dir):
+        tpl = _get_template(os.path.join(tpl_dir, name))
+        name_no_ext, _ = os.path.splitext(name)
+        tpls[name_no_ext] = tpl
+    return tpls
+
+
+def _get_template(filename):
+    with open(filename, 'r', encoding='utf8') as fp:
+        return fp.read()
+
+
+if __name__ == '__main__':
+    generate()
+