Preserve numbers for repeated footnote references

README.md

@@ -100,6 +100,9 @@ as a script:
 >>> markdown2.markdown("*boo!*", extras=["footnotes"])
 '<p><em>boo!</em></p>\n'
 ```
+The `footnotes` extra keeps the same number when a footnote is referenced more
+than once.
+
 There are a number of currently implemented extras for tables, footnotes,
 syntax coloring of `<pre>`-blocks, auto-linking patterns, table of contents,
 Smarty Pants (for fancy quotes, dashes, etc.) and more. See the [Extras

lib/markdown2.py

@@ -422,6 +422,7 @@ def _setup_extras(self):
             # https://docs.python.org/3/whatsnew/3.7.html#summary-release-highlights
             self.footnotes = OrderedDict()
             self.footnote_ids = []
+            self._footnote_numbers = {}
             self._footnote_marker = _hash_text('<<footnote>>')
         if "header-ids" in self.extras:
             if not hasattr(self, '_count_from_header_id') or self.extras['header-ids'].get('reset-count', False):
@@ -586,9 +587,12 @@ def toc_sort(entry):
     def _do_footnote_marker(self, text):
         def footnote_sub(match):
             normed_id = match.group(1)
-            if normed_id not in self.footnote_ids:
+            if normed_id not in self._footnote_numbers:
                 self.footnote_ids.append(normed_id)
-            return str(len(self.footnote_ids))
+                self._footnote_numbers[normed_id] = (
+                    len(self._footnote_numbers) + 1
+                )
+            return str(self._footnote_numbers[normed_id])
 
         return re.sub(r'%s-(.*?)(?=</a></sup>)' % self._footnote_marker, footnote_sub, text)
 

test/test_markdown2.py

@@ -230,6 +230,14 @@ def test_header_ids_from_file_vars(self):
             self.assertIn('<h1 id="{}">Heading</h1>'.format(heading_id), html)
             self.assertEqual(md.convert("# Heading\n"), "<h1>Heading</h1>\n")
 
+    def test_footnote_numbers_reset_between_conversions(self):
+        md = markdown2.Markdown(extras=["footnotes"])
+        md.convert("First[^first], second[^second].\n\n"
+                   "[^first]: First note.\n[^second]: Second note.")
+        html = md.convert("Second[^second].\n\n[^second]: Second note.")
+        self.assertIn('<a href="#fn-second">1</a>', html)
+        self.assertIn('<li id="fn-second">', html)
+
     def test_many_distinct_code_spans(self):
         source = '\n\n'.join('`value_%s`' % i for i in range(1000))
         expected = '\n\n'.join('<p><code>value_%s</code></p>' % i for i in range(1000)) + '\n'

test/tm-cases/repeated_footnote_labels.html

@@ -0,0 +1,24 @@
+<p>First<sup class="footnote-ref" id="fnref-first"><a href="#fn-first">1</a></sup>, second<sup class="footnote-ref" id="fnref-second"><a href="#fn-second">2</a></sup>, and first again<sup class="footnote-ref" id="fnref-first"><a href="#fn-first">1</a></sup>.</p>
+
+<ul>
+<li>Second again<sup class="footnote-ref" id="fnref-second"><a href="#fn-second">2</a></sup>.</li>
+<li>Third<sup class="footnote-ref" id="fnref-third"><a href="#fn-third">3</a></sup>.</li>
+<li>First again<sup class="footnote-ref" id="fnref-first"><a href="#fn-first">1</a></sup>.</li>
+</ul>
+
+<div class="footnotes">
+<hr />
+<ol>
+<li id="fn-second">
+<p>Second note referencing first<sup class="footnote-ref" id="fnref-first"><a href="#fn-first">1</a></sup>.&#160;<a href="#fnref-second" class="footnoteBackLink" title="Jump back to footnote 1 in the text.">&#8617;</a></p>
+</li>
+
+<li id="fn-first">
+<p>First note.&#160;<a href="#fnref-first" class="footnoteBackLink" title="Jump back to footnote 2 in the text.">&#8617;</a></p>
+</li>
+
+<li id="fn-third">
+<p>Third note referencing second<sup class="footnote-ref" id="fnref-second"><a href="#fn-second">2</a></sup>.&#160;<a href="#fnref-third" class="footnoteBackLink" title="Jump back to footnote 3 in the text.">&#8617;</a></p>
+</li>
+</ol>
+</div>

test/tm-cases/repeated_footnote_labels.opts

@@ -0,0 +1 @@
+{"extras": ["footnotes"]}

test/tm-cases/repeated_footnote_labels.text

@@ -0,0 +1,9 @@
+First[^first], second[^second], and first again[^first].
+
+- Second again[^second].
+- Third[^third].
+- First again[^first].
+
+[^second]: Second note referencing first[^first].
+[^first]: First note.
+[^third]: Third note referencing second[^second].