Add note about tag navigation

docs/colophon.md

@@ -4,7 +4,7 @@ hide: [toc]
 
 # Colophon
 
-This site is built with [`mkdocs`](https://www.mkdocs.org/) and [`mkdocs-material`](https://squidfunk.github.io/mkdocs-material/). Sure, it's designed for docs, but with a few modifications (like the [`tags`](https://squidfunk.github.io/mkdocs-material/plugins/tags/) plugin) it can be used for notes. I made some fairly large modifications to how tags work, so the sidebar is structured by tag rather than by directory (directories are fairly arbitrary, and might get removed entirely in future).
+This site is built with [`mkdocs`](https://www.mkdocs.org/) and [`mkdocs-material`](https://squidfunk.github.io/mkdocs-material/). Sure, it's designed for docs, but with a few modifications (like the [`tags`](https://squidfunk.github.io/mkdocs-material/plugins/tags/) plugin) it can be used for notes. I made some fairly [large modifications](notes/mkdocs-nav-by-tag.md) to how tags work, so the sidebar is structured by tag rather than by directory (directories are fairly arbitrary, and might get removed entirely in future).
 
 It's been through a few iterations in the past, starting with [`gatsby-theme-code-notes`](https://github.com/mrmartineau/gatsby-theme-code-notes/), on to [`hugo-theme-notes`](https://github.com/RealOrangeOne/hugo-theme-notes/), and finally here.
 

docs/notes/mkdocs-nav-by-tag.md

@@ -0,0 +1,16 @@
+---
+title: Navigate mkdocs by tag
+tags:
+  - mkdocs
+---
+
+The sidebar for this notes site uses tags for the hierarchy, rather than by the filesystem structure.
+
+This works by retrieving the tags for each note, creating fake sections for each, and replacing the existing sections with those.
+
+!!! warning
+    Here be dragons.
+
+```python
+{! ../hooks/tag_nav.py !}
+```

hooks/notes.py

@@ -1,8 +1,5 @@
 import jinja2
-from mkdocs.structure.nav import Navigation, Section
-from collections import defaultdict
-from mkdocs.utils import meta
-from mkdocs.plugins import event_priority
+from mkdocs.structure.nav import Navigation
 
 @jinja2.pass_context
 def get_page(context, slug):
@@ -33,48 +30,3 @@ def on_env(env, config, files):
     env.tests["startswith"] = str.startswith
     env.globals["get_page"] = get_page
     env.globals["get_notes"] = get_notes
-
-
-class TagSection(Section):
-    """
-    A modified section which is active if any of its children are active
-    (regardless of what mkdocs tells it).
-    """
-    @property
-    def active(self):
-        return any(c.active for c in self.children)
-
-    @active.setter
-    def active(self, value: bool):
-        pass
-
-
-@event_priority(100)
-def on_nav(nav: Navigation, config, files):
-    """
-    Structure the nav sections by
-    """
-    notes_section, notes = get_notes_from_nav(nav)
-
-    notes_page = notes_section.children[0]
-
-    pages_to_tag = defaultdict(list)
-
-    orphan_pages = []
-
-    for note in notes:
-        with open(note.file.abs_src_path) as f:
-            _, metadata = meta.get_data(f.read())
-
-        if tags := metadata.get("tags"):
-            for tag in tags:
-                pages_to_tag[tag].append(note)
-        else:
-            orphan_pages.append(note)
-
-    tag_sections = [
-        TagSection(tag, pages)
-        for tag, pages in pages_to_tag.items()
-    ]
-
-    notes_section.children = tag_sections + orphan_pages + [notes_page]

hooks/tag_nav.py

@@ -0,0 +1,55 @@
+import sys
+import os
+
+sys.path.insert(0, os.path.dirname(__file__))
+
+from notes import get_notes_from_nav
+from mkdocs.structure.nav import Navigation, Section
+from collections import defaultdict
+from mkdocs.utils import meta
+from mkdocs.plugins import event_priority
+
+
+class TagSection(Section):
+    """
+    A modified section which is active if any of its children are active
+    (regardless of what mkdocs tells it).
+    """
+    @property
+    def active(self):
+        return any(c.active for c in self.children)
+
+    @active.setter
+    def active(self, value: bool):
+        pass
+
+
+@event_priority(100)
+def on_nav(nav: Navigation, config, files):
+    """
+    Structure the nav sections by tag
+    """
+    notes_section, notes = get_notes_from_nav(nav)
+
+    notes_page = notes_section.children[0]
+
+    pages_to_tag = defaultdict(list)
+
+    orphan_pages = []
+
+    for note in notes:
+        with open(note.file.abs_src_path) as f:
+            _, metadata = meta.get_data(f.read())
+
+        if tags := metadata.get("tags"):
+            for tag in tags:
+                pages_to_tag[tag].append(note)
+        else:
+            orphan_pages.append(note)
+
+    tag_sections = [
+        TagSection(tag, pages)
+        for tag, pages in pages_to_tag.items()
+    ]
+
+    notes_section.children = tag_sections + orphan_pages + [notes_page]

mkdocs.yml

@@ -53,6 +53,7 @@ theme:
 
 hooks:
   - hooks/notes.py
+  - hooks/tag_nav.py
 
 # Extensions
 markdown_extensions: