added linking support to headers

src/dragonglass/mparse.py

@@ -45,6 +45,7 @@ COMMENT_MARKER = '%%'
 # Tags pattern
 OBSTAG_PATTERN = r'#([a-zA-Z0-9/_-]+)'
 
+
 def is_proper_url(s: str) -> bool:
     """
     Checks to see if a string is a "proper" URL.
@@ -75,6 +76,19 @@ def sanitize_reference(s: str) -> str:
     return rc
 
 
+def make_hash_value(s: str) -> str:
+    """
+    Create a secure hash value for the passed-in string.
+
+    Args:
+        s (str): The string to be hashed.
+
+    Returns:
+        A secure hash value for the string, expressed as hex digits.
+    """
+    return hashlib.sha1(bytes(s, 'utf-8')).hexdigest()
+
+
 class MetaStripper(Extension):
     """
     An extension that strips the metadata off the front of Obsidian pages, as it's already been parsed in an
@@ -110,6 +124,82 @@ class MetaStripper(Extension):
         md.preprocessors.register(MetaStripper.MetaStripperProc(md), 'metastripper', PRIO_BASE)
 
 
+class ObsidianHeaders(Extension):
+    """An extension that augments the existing header processing."""
+
+    class HashHeaderProcessor(BlockProcessor):
+        """ Process Hash Headers. """
+
+        # Detect a header at start of any line in block
+        RE = re.compile(r'(?:^|\n)(?P<level>#{1,6})(?P<header>(?:\\.|[^\\])*?)#*(?:\n|$)')
+
+        def test(self, parent: etree.Element, block: str) -> bool:
+            """
+            Tests to see whether the current block can be handled by this processor.
+
+            Args:
+                parent (etree.Element): The current parent element.
+                block (str): The current block to be tested.
+
+            Returns:
+                bool: ``True`` if this processor can handle the block, ``False`` if not.
+            """
+            return bool(self.RE.search(block))
+
+        def run(self, parent: etree.Element, blocks: list[str]) -> None:
+            """
+            Processes the text in the current block and adds elements to the parent element.
+
+            Args:
+                parent (etree.Element): Parent element to add new subelements to.
+                blocks (list[str]): Blocks of text to be processed. The first block in this list is the one for which
+                    the ``test`` method returned ``True``.  This method should remove any parsed text from the
+                    ``block`` list before it returns.
+
+            Returns:
+                bool: ``True`` if text was parsed by this method, ``False`` if not.
+            """
+            block = blocks.pop(0)
+            m = self.RE.search(block)
+            if m:
+                before = block[:m.start()]  # All lines before header
+                after = block[m.end():]     # All lines after header
+                if before:
+                    # As the header was not the first line of the block and the
+                    # lines before the header must be parsed first,
+                    # recursively parse this lines as a block.
+                    self.parser.parseBlocks(parent, [before])
+
+                # Get the header text and its hash.
+                hdr_text = m.group('header').strip()
+                hval = make_hash_value(hdr_text)
+
+                # Create header (with anchor) using named groups from RE
+                a = etree.SubElement(parent, 'a', {'class': 'hdrref', 'name': f"hdr-{hval}"})
+                h = etree.SubElement(a, 'h%d' % len(m.group('level')))
+                h.text = hdr_text
+                if after:
+                    # Insert remaining lines as first block for future parsing.
+                    if self.parser.state.isstate('looselist'):
+                        # This is a weird edge case where a header is a child of a loose list
+                        # and there is no blank line after the header. To ensure proper
+                        # parsing, the line(s) after need to be detabbed. See #1443.
+                        after = self.looseDetab(after)
+                    blocks.insert(0, after)
+            else:  # pragma: no cover
+                # This should never happen, but just in case...
+                logger.warn("We've got a problem header: %r" % block)
+
+    def extendMarkdown(self, md: Markdown) -> None:  # noqa: N802
+        """
+        Registers the header processor with the Markdown parser.
+
+        Args:
+            md (markdown.Markdown): The Markdown parser to register the patterns with.
+        """
+        md.parser.blockprocessors.register(ObsidianHeaders.HashHeaderProcessor(md.parser), 'hashheader', 70)
+
+
 class ObsidianImages(Extension):
     """An extension that supports image tags the way Obsidian handles them."""
     __DIMS = re.compile(r'(.*)\|[ ]*(\d+)(?:[ ]*x[ ]*(\d+))?')
@@ -328,6 +418,11 @@ class ObsidianLinks(Extension):
         if len(t) > 1:
             text = t[1]
             contents = t[0].rstrip('\\')
+        t = contents.split('#')
+        hashloc = None
+        if len(t) > 1:
+            hashloc = make_hash_value(t[1].strip())
+            contents = t[0]
 
         assert self._context.src_index is not None
         node, _ = self._context.src_index.lookup(contents)
@@ -336,8 +431,11 @@ class ObsidianLinks(Extension):
         if node:
             # record a backlink from the current node to the found one
             node.backlinks.add(self._context.current_node)
-            return node.link_target(self._context.url_prefix,
-                                    self._context.current_node if self._context.relative_links else None), text
+            link = node.link_target(self._context.url_prefix,
+                                    self._context.current_node if self._context.relative_links else None)
+            if hashloc:
+                link = f"{link}#hdr-{hashloc}"
+            return link, text
         return None, text
 
     class ObsidianLinksProc(InlineProcessor):
@@ -856,7 +954,7 @@ class ObsidianStyleFootnotes(FootnoteExtension):
 
                 if m_inline:
                     footnote = m_inline.group(1).strip()
-                    id = hashlib.sha1(bytes(f"{footnote}{self._inlines_nonce}", 'utf-8')).hexdigest()
+                    id = make_hash_value(f"{footnote}{self._inlines_nonce}")
                     self._inlines_nonce += 1
                     self.footnotes.setFootnote(id, footnote)
                     blocks.insert(0, block[:m_inline.start(0)].rstrip()
@@ -1114,6 +1212,7 @@ def create_markdown_parser(context: Context) -> markdown.Markdown:
                                          'tables',
                                          MetaStripper(),
                                          ObsidianComments(),
+                                         ObsidianHeaders(),
                                          ObsidianStyleFootnotes(SUPERSCRIPT_TEXT='[{}]', SEPARATOR='-'),
                                          ObsidianStyleBlockquotes(context),
                                          ObsidianImages(context),

src/dragonglass/style.py

@@ -18,6 +18,10 @@ STYLESHEET_DATA = """/* Dragonglass default CSS file - ensure all generated HTML
 a {
     color: #8a5cf5;     
 }
+a.hdrref {
+    color: inherit;
+    text-decoration: none;
+}
 .{{ invalid_reference }} {
     color: #ad8df8;
     text-decoration: underline;