Skip the backslash-escape scan for text without a backslash

CHANGES.md

@@ -2,6 +2,7 @@
 
 ## python-markdown2 2.5.6 (not yet released)
 
+- [pull #762] Speed up documents with many links by skipping the backslash-escape scan for text without a backslash
 - [pull #746] Preserve query strings and fragments in `markdown-file-links` conversions, including reference-link targets.
 - [pull #739] Fix `header-ids` extra putting sanitized HTML into header ids in safe mode, which allowed attribute injection (#649)
 - [pull #732] Fix excessive CPU use in the inline HTML tokenizer on repeated unclosed tag fragments (#707)

lib/markdown2.py

@@ -2371,6 +2371,9 @@ def incomplete_tags_sub(match):
         return text
 
     def _encode_backslash_escapes(self, text: str) -> str:
+        # Every search string below starts with a backslash.
+        if '\\' not in text:
+            return text
         for ch, escape in list(self._escape_table.items()):
             text = text.replace("\\"+ch, escape)
         return text

test/test_markdown2.py

@@ -254,6 +254,17 @@ def test_many_distinct_code_spans(self):
         expected = '\n\n'.join('<p><code>value_%s</code></p>' % i for i in range(1000)) + '\n'
         self.assertEqual(markdown2.markdown(source), expected)
 
+    def test_many_links_with_backslash_escapes(self):
+        link = 'Paragraph %s has [a link](https://example.com/%s).'
+        html = ('<p>Paragraph %s has '
+                '<a href="https://example.com/%s">a link</a>.</p>')
+        escaped = r'An \*escaped\* star and a C:\dir path.'
+        source = '\n\n'.join([link % (i, i) for i in range(1000)] + [escaped])
+        expected = '\n\n'.join(
+            [html % (i, i) for i in range(1000)]
+            + [r'<p>An *escaped* star and a C:\dir path.</p>']) + '\n'
+        self.assertEqual(markdown2.markdown(source), expected)
+
     def test_unescape_nested_tokens(self):
         md = markdown2.Markdown()
         md.reset()