Recognize additional URL schemes in automatic links

docs/changelog.md

@@ -16,6 +16,8 @@ See the [Contributing Guide](contributing.md) for details.
 
 ### Fixed
 
+* Support automatic links with URL schemes other than HTTP and FTP, such as
+  `<ssh://example.org>` (#1244).
 * Fix quadratic-time id generation in the `toc` extension when many headers
   share the same text.
 * Strip complete HTML tags with quoted `>` characters from `toc` labels and

docs/index.md

@@ -118,6 +118,13 @@ are summarized below:
     foreseeable future. That said, the [Sane List Extension](extensions/sane_lists.md)
     is available to provide a less surprising behavior.
 
+* __Automatic Links__
+
+    Automatic links recognize URL schemes followed by `://`, including schemes
+    other than HTTP and FTP, such as `<ssh://example.org>` and
+    `<git+ssh://example.org/repo>`. URI forms without `://`, such as
+    `<urn:foo>`, continue to be treated as raw HTML.
+
 Support
 -------
 

markdown/inlinepatterns.py

@@ -119,7 +119,7 @@ def build_inlinepatterns(md: Markdown, **kwargs: Any) -> util.Registry[InlinePro
 IMAGE_REFERENCE_RE = IMAGE_LINK_RE
 """ Match start of image reference (`![alt text][2]`). """
 
-AUTOLINK_RE = r'<((?:[Ff]|[Hh][Tt])[Tt][Pp][Ss]?://[^<>]*)>'
+AUTOLINK_RE = r'<([A-Za-z][A-Za-z0-9+.-]*://[^<>]*)>'
 """ Match an automatic link (`<http://www.example.com>`). """
 
 AUTOMAIL_RE = r'<([^<> !]+@[^@<> ]+)>'

tests/test_syntax/inline/test_autolinks.py

@@ -24,6 +24,72 @@
 
 class TestAutomaticLinks(TestCase):
 
+    def test_url_schemes(self):
+        for url in (
+            'http://example.org',
+            'https://example.org',
+            'ftp://example.org',
+            'ftps://example.org',
+            'HtTpS://example.org',
+            'ssh://example.org',
+            'git://example.org/repo',
+            's3://bucket/key',
+            'git+ssh://example.org/repo',
+            'x.y-z://example.org',
+        ):
+            with self.subTest(url=url):
+                self.assertMarkdownRenders(
+                    f'<{url}>',
+                    f'<p><a href="{url}">{url}</a></p>'
+                )
+
+    def test_url_schemes_with_userinfo(self):
+        for url in (
+            'ssh://[email protected]/path',
+            'git+ssh://[email protected]/repo.git',
+        ):
+            with self.subTest(url=url):
+                self.assertMarkdownRenders(
+                    f'<{url}>',
+                    f'<p><a href="{url}">{url}</a></p>'
+                )
+
+    def test_url_scheme_with_query(self):
+        self.assertMarkdownRenders(
+            '<ssh://example.org/path?q=one&x=two>',
+            '<p><a href="ssh://example.org/path?q=one&amp;x=two">'
+            'ssh://example.org/path?q=one&amp;x=two</a></p>'
+        )
+
+    def test_adjacent_url_schemes(self):
+        self.assertMarkdownRenders(
+            'Before <ssh://one><git://two> after',
+            '<p>Before <a href="ssh://one">ssh://one</a>'
+            '<a href="git://two">git://two</a> after</p>'
+        )
+
+    def test_url_scheme_without_closing_bracket(self):
+        self.assertMarkdownRenders(
+            '<ssh://example.org',
+            '<p>&lt;ssh://example.org</p>'
+        )
+
+    def test_url_scheme_in_code_span(self):
+        self.assertMarkdownRenders(
+            '`<ssh://example.org>`',
+            '<p><code>&lt;ssh://example.org&gt;</code></p>'
+        )
+
+    def test_invalid_url_schemes(self):
+        for source, expected in (
+            ('<1http://example.org>', '<p>&lt;1http://example.org&gt;</p>'),
+            ('<git_ssh://example.org>', '<p><git_ssh://example.org></p>'),
+            ('<urn:foo>', '<p><urn:foo></p>'),
+            ('<em>boo!</em>', '<p><em>boo!</em></p>'),
+        ):
+            with self.subTest(source=source):
+                self.assertMarkdownRenders(source, expected)
+
     def test_email_address(self):
         self.assertMarkdownRenders(
             'asdfasdfadsfasd <[email protected]> or you can say ',