added support for tags, both in metadata and inline in the text

doc/metadata-values.txt

@@ -2,8 +2,7 @@ METADATA VALUES USED BY DRAGONGLASS
 
 aliases
 	(Obsidian standard metadata)
-	List of alternative names that can be used to link to a
+	List of alternative names that can be used to link to a particular page.
-	particular page.
 
 description
     (Obsidian Publish standard metadata)
@@ -13,6 +12,10 @@ publish
     (Obsidian Publish standard metadata)
     If this boolean value is False, the page will not be published.
 
+tags
+    (Obsidian standard metadata)
+    List of tags for this page.  Tags may be defined here or inline in the text.
+
 template
     The file name of the template to be used to render this page, overriding the default.
 

doc/template-vars.txt

@@ -17,6 +17,9 @@ dragonglass_version
 python_version
     The version number of Python that's running dragonglass.
 
+tags:
+    A list of all tags the page being rendered has, in sorted order.
+
 text
     The text of the page being rendered.
 

src/dragonglass/mparse.py

@@ -42,6 +42,8 @@ INLINE_FOOTNOTE_REF_PATTERN = INLINE_FOOTNOTE_REF_PREFIX + "{}" + ETX
 # Obsidian comment marker
 COMMENT_MARKER = '%%'
 
+# Tags pattern
+OBSTAG_PATTERN = r'#([a-zA-Z0-9/_-]+)'
 
 def is_proper_url(s: str) -> bool:
     """
@@ -1033,6 +1035,49 @@ class ObsidianStyleBlockquotes(Extension):
                                            'callout-text', 11)
 
 
+class ObsidianTags(Extension):
+    def __init__(self, context: Context, **kwargs: dict[str, Any]) -> None:
+        """
+        Initialize the ObsidianStyleBlockquotes extension.
+
+        Args:
+            context (Context): Context object that contains configuration information.
+            **kwargs (dict[str, Any]: Additional configuration information.
+        """
+        super(ObsidianTags, self).__init__(**kwargs)
+        self._context = context
+
+    def stash_tag(self, tagname: str) -> None:
+        self._context.current_node.stash_tag(tagname)
+
+    class ObsidianTagsProcessor(InlineProcessor):
+        def __init__(self, pattern: str, md: markdown.Markdown, extref: Any) -> None:
+            """
+            Initialize the GenericLinksProc.
+
+            Args:
+                pattern (str): Regular expression pattern to be matched by this processor.
+                md (markdown.Markdown): Reference to the Markdown parser.
+                extref (ObsidianLinks): Backreference to the outer object.
+            """
+            super(ObsidianTags.ObsidianTagsProcessor, self).__init__(pattern, md)
+            self._extref = extref
+
+        def handleMatch(self, m: re.Match[str], data: str) -> tuple[etree.Element | None, int | None, int | None]:  # noqa: N802
+            tagname = m.group(1)
+            if not re.search(r'[^0-9]', tagname):
+                return None, None, None
+            self._extref.stash_tag(tagname)
+            tag = etree.Element('span')
+            tag.attrib['class'] = "tag"
+            tag.text = f"#{tagname}"
+            return tag, m.start(0), m.end(0)
+
+    def extendMarkdown(self, md) -> None:
+        md.inlinePatterns.register(ObsidianTags.ObsidianTagsProcessor(OBSTAG_PATTERN, md, self),
+                                   'obsidian-tags', PRIO_BASE + 40)
+
+
 def create_markdown_parser(context: Context) -> markdown.Markdown:
     """
     Creates a Markdown parser with all our extensions loaded.
@@ -1063,5 +1108,6 @@ def create_markdown_parser(context: Context) -> markdown.Markdown:
                                          ObsidianImages(context),
                                          ObsidianLinks(context),
                                          ObsidianLists(),
-                                         ObsidianInlines()],
+                                         ObsidianInlines(),
+                                         ObsidianTags(context)],
                              extension_configs=extconfig)

src/dragonglass/style.py

@@ -36,6 +36,17 @@ blockquote {
 span.task-list-item-checked {
     text-decoration-line: line-through;
 }
+span.tag {
+    background-color: hsla(258, 88%, 66%, 0.1);
+    border: 0px solid hsla(258, 88%, 66%, 0.15);
+    border-radius: 2em;
+    color: hsl(258, 88%, 66%);
+    font-size: 0.875em;
+    font-weight: inherit;
+    text-decoration: none;
+    padding: 0.25em 0.65em;
+    line-height: 1;
+}
 div.codehilite {
     padding: 0.1em 0.25em;
     margin-top: 0.5em;

src/dragonglass/tree.py

@@ -44,6 +44,7 @@ class SourceNode:
         self._path = path
         self._is_dir = is_dir
         self._is_md = path.match(MARKDOWN_PAT)
+        self._tags: dict[str, str] = {}
         self.metadata: dict[str, Any] = {}
         self.text: str | None = None
         self.backlinks: set[Any] = set()
@@ -117,6 +118,17 @@ class SourceNode:
             return urlquote(xpath.relative_to(rel_path.parent, walk_up=True).as_posix())
         return urlquote(prefix + xpath.as_posix())
 
+    def stash_tag(self, tagname: str) -> None:
+        """
+        Add a tag to the set of tags in this node.
+
+        Args:
+            tagname (str): The tag name to be added.
+        """
+        rtag = tagname.lower()
+        if rtag not in self._tags:
+            self._tags[rtag] = tagname
+
     def load_metadata(self) -> None:
         """
         Loads the metadata for this particular node and saves it in the "metadata" attribute.
@@ -133,6 +145,9 @@ class SourceNode:
                         metalines.append(cur_line)
                         cur_line = f.readline()
                     self.metadata = yaml.full_load(''.join(metalines))
+            # Load up the initial tags.
+            for tag in self.metadata.get("tags", []):
+                self.stash_tag(tag)
 
     def parse_markdown(self, markdown_parser: markdown.Markdown) -> None:
         """
@@ -156,7 +171,8 @@ class SourceNode:
         return {
             "text": self.text,
             "title": self.page_title,
-            "description": self.metadata.get("description", "")
+            "description": self.metadata.get("description", ""),
+            "tags": [self._tags[n] for n in sorted(self._tags.keys())]
         }