Add support to handle custom HTML tags

docs/src/markdown/about/changelog.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 10.14
+
+-   **NEW**: Blocks.HTML: Add new `custom` option to specify tags and the assumed handling for them when automatic mode
+    is assumed. This can also be used to override the handling for recognized tags with automatic handling.
+-   **FIX**: Fix tests to pass with Pygments 2.19+.
+
 ## 10.13
 
 -   **NEW**: Snippets: Allow multiple line numbers or line number blocks separated by `,`.

docs/src/markdown/extensions/blocks/api.md

@@ -290,7 +290,7 @@ Result\ Value | Description
 When using `raw` mode, all text will be accumulated under the specified element as an [`AtomicString`][atomic]. If
 nothing is done with the content during the [`on_end` event](#on_end-event), all the content will be HTML escaped by the
 Python Markdown parser. If desired, the content can be placed into the Python Markdown [HTML stash][stash] which will
-protect it from any other rouge Treeprocessors. Keep in mind, if the content is stashed HTML escaping will not be
+protect it from any other rouge Treeprocessors. Keep in mind, if the content is stashed, HTML escaping will not be
 applied automatically, so HTML escape if it is required.
 
 /// warning | Indent Raw Content

docs/src/markdown/extensions/blocks/plugins/html.md

@@ -109,6 +109,49 @@ some *markdown* content
 ////
 ///
 
+## Custom Tag Handling
+
+It is possible that in the future new tags could be added to the HTML spec, and it is also possible that the extension
+may not recognize such tags for some length of time. While such tags can be added in future releases, the HTML extension
+allows for users to specify such tags to navigate around such issues, or even make up their own tags.
+
+To teach the HTML extension about unknown tags, simply use the `custom` [option](#global-options) to specify a tag name
+and the assumed default `mode`.
+
+```py3
+import markdown
+from pymdownx.blocks.html import HTML
+extensions = ['pymdownx.blocks.html']
+extension_configs = {
+    'pymdown.blocks.html': {
+        'custom': [
+            {'tag': 'sometag', 'mode': 'block'}
+        ]
+    }
+}
+md = markdown.Markdown(extensions=extensions, extension_configs=extension_configs)
+```
+
+Then you can use your custom tag knowing it will be handled properly.
+
+```
+/// html | sometag
+
+Some block content.
+
+- List item A.
+
+- List item B.
+///
+
+```
+
+## Global Options
+
+Options  | Type            | Descriptions
+-------- | --------------- | ------------
+`custom` | \[dictionary\] | Specify custom tags with assumed default handling.
+
 ## Per Block Options
 
 Options      | Type       | Descriptions

pymdownx/__meta__.py

@@ -185,5 +185,5 @@ def parse_version(ver, pre=False):
     return Version(major, minor, micro, release, pre, post, dev)
 
 
-__version_info__ = Version(10, 13, 0, "final")
+__version_info__ = Version(10, 14, 0, "final")
 __version__ = __version_info__._get_canonical()

pymdownx/blocks/html.py

@@ -39,6 +39,7 @@
 RE_ATTR = re.compile(fr'(?P<attr_name>{IDENTIFIER}){ATTR}', flags=re.I | re.X)
 
 ATTRIBUTES = {'id': RE_ID, 'class': RE_CLASS, 'attr': RE_ATTRS}
+VALID_MODES = {'auto', 'inline', 'block', 'raw', 'html'}
 
 
 def parse_selectors(selector):
@@ -125,13 +126,17 @@ class HTML(Block):
     NAME = 'html'
     ARGUMENT = True
     OPTIONS = {
-        'markdown': ['auto', type_string_in(['auto', 'inline', 'block', 'raw', 'html'])]
+        'markdown': ['auto', type_string_in(VALID_MODES)]
     }
 
     def __init__(self, length, tracker, md, config):
         """Initialize."""
 
         self.markdown = None
+        self.custom = {}
+        for entry in config.get('custom'):
+            mode = entry.get('mode', 'auto')
+            self.custom[entry['tag']] = mode if mode in VALID_MODES else 'auto'
         super().__init__(length, tracker, md, config)
 
     def on_validate(self, parent):
@@ -148,6 +153,10 @@ def on_markdown(self):
         """Check if this is atomic."""
 
         mode = self.options['markdown']
+        if mode == 'auto':
+            tag = self.tag.lower()
+            mode = self.custom.get(tag, mode)
+
         if mode == 'html':
             mode = 'raw'
         return mode
@@ -167,6 +176,10 @@ def on_end(self, block):
         """On end event."""
 
         mode = self.options['markdown']
+        if mode == 'auto':
+            tag = self.tag.lower()
+            mode = self.custom.get(tag, mode)
+
         if (mode == 'auto' and self.is_html(block)) or mode == 'html':
             block.text = self.md.htmlStash.store(block.text)
         elif (mode == 'auto' and self.is_raw(block)) or mode == 'raw':
@@ -176,6 +189,18 @@ def on_end(self, block):
 class HTMLExtension(BlocksExtension):
     """HTML Blocks Extension."""
 
+    def __init__(self, *args, **kwargs):
+        """Initialize."""
+
+        self.config = {
+            "custom": [
+                [],
+                "Specify handling for custom blocks."
+            ]
+        }
+
+        super().__init__(*args, **kwargs)
+
     def extendMarkdownBlocks(self, md, block_mgr):
         """Extend Markdown blocks."""
 

tests/test_extensions/test_blocks/test_html.py

@@ -6,6 +6,13 @@ class TestBlocksHTML(util.MdCase):
     """Test Blocks HTML cases."""
 
     extension = ['pymdownx.blocks.html', 'md_in_html']
+    extension_configs = {
+        'pymdownx.blocks.html': {
+            'custom': [
+                {'tag': 'custom', 'mode': 'block'}
+            ]
+        }
+    }
 
     def test_bad_tag(self):
         """Test bad HTML tag."""
@@ -323,3 +330,38 @@ def test_html_and_script(self):
             ''',
             True
         )
+
+    def test_custom(self):
+        """Test custom block handling."""
+
+        self.check_markdown(
+            R'''
+            /// html | custom
+            - a
+            - b
+            ///
+            ''',
+            '''
+            <custom><ul><li>a</li><li>b</li></ul></custom>
+            ''',
+            True
+        )
+
+    def test_custom_override(self):
+        """Test custom block handling but mode is overridden."""
+
+        self.check_markdown(
+            R'''
+            /// html | custom
+                markdown: inline
+
+            - a
+            - b
+            ///
+            ''',
+            '''
+            <custom>- a
+            - b</custom>
+            ''',
+            True
+        )