support gitiles smart quoting

Convert dumb single/double quotes to smart quotes just like gitiles.

R=dpranke@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2740863004
Cr-Commit-Position: refs/heads/master@{#455693}

tools/md_browser/gitiles_smart_quotes.py

+# -*- coding: utf-8 -*-
+# Copyright 2017 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Implements Gitiles' smart quotes.
+
+This extention converts dumb quotes into smart quotes like Gitiles:
+
+https://gerrit.googlesource.com/gitiles/+/master/gitiles-servlet/src/main/java/com/google/gitiles/doc/SmartQuotedExtension.java
+"""
+
+from markdown.inlinepatterns import Pattern
+from markdown.extensions import Extension
+
+
+class _GitilesSmartQuotesPattern(Pattern):
+  """Process Gitiles' dumb->smart quotes."""
+
+  QUOTES = {
+      '"': (u'“', u'”'),
+      "'": (u'‘', u'’'),
+  }
+
+  def handleMatch(self, m):
+    lq, rq = self.QUOTES[m.group(2)]
+    return u'%s%s%s' % (lq, m.group(3), rq)
+
+
+class _GitilesSmartQuotesExtension(Extension):
+  """Add Gitiles' smart quotes to Markdown."""
+  def extendMarkdown(self, md, md_globals):
+    md.inlinePatterns.add('gitilessmartquotes',
+                          _GitilesSmartQuotesPattern(r"""(['"])([^\2]+)\2"""),
+                          '<emphasis')
+
+
+def makeExtension(*args, **kwargs):
+  return _GitilesSmartQuotesExtension(*args, **kwargs)

tools/md_browser/md_browser.py

@@ -149,6 +149,7 @@ class Handler(SimpleHTTPServer.SimpleHTTPRequestHandler):
         'markdown.extensions.toc',
         'gitiles_autolink',
         'gitiles_ext_blocks',
+        'gitiles_smart_quotes',
     ]
     extension_configs = {
         'markdown.extensions.toc': {