Add 'slug_source' path handler (#3831)

This allows the creation of links to the source for a blog post.  Note
that this also works for translations, so the link will always point
to the correct source even in translations.

Author: laodzu

AUTHORS.txt

@@ -35,6 +35,7 @@
 * `dastagg <https://github.com/dastagg>`_
 * `David Barragán Merino <https://github.com/bameda>`_
 * `David Beath <https://github.com/DBeath>`_
+* `Detlev Zundel <https://github.com/laodzu>`_
 * `Dhruv Baldawa <https://github.com/dhruvbaldawa>`_
 * `Dirk Engling <https://github.com/erdgeist>`_
 * `Dmitry Verkhoturov <https://github.com/paskal>`_

CHANGES.txt

@@ -10,6 +10,7 @@ Features
   (either ``mako.lookup.TemplateLookup`` or ``jinja2.Environment``)
   via an optional ``conf.py`` method ``TEMPLATE_ENGINE_FACTORY``.
 * Switch to pyproject.toml
+* Add path handler ``slug_source`` linking to source of post.
 
 Bugfixes
 --------

docs/path_handlers.rst

@@ -197,6 +197,14 @@ slug
     link://slug/yellow-camaro => /posts/cars/awful/yellow-camaro/index.html
 
 
+slug_source
+    Return a link to source for a post with given slug, if not ambiguous.
+
+    Example:
+
+    link://slug_source/yellow-camaro => /posts/cars/awful/yellow-camaro.rst
+
+
 tag
     A link to a tag's page. Takes page number as optional keyword argument.
 

nikola/nikola.py

@@ -379,6 +379,7 @@ def __init__(self, **config) -> None:
         # Register our own path handlers
         self.path_handlers = {
             'slug': self.slug_path,
+            'slug_source': self.slug_source,
             'post_path': self.post_path,
             'root': self.root_path,
             'filename': self.filename_path,
@@ -1970,6 +1971,21 @@ def slug_path(self, name, lang):
                 utils.LOGGER.warning('Ambiguous path request for slug: {0}'.format(name))
             return [_f for _f in results[0].permalink(lang).split('/')]
 
+    def slug_source(self, name, lang):
+        """Return a link to source for a post with given slug, if not ambiguous.
+
+        Example:
+
+        link://slug_source/yellow-camaro => /posts/cars/awful/yellow-camaro.rst
+        """
+        results = [p for p in self.timeline if p.meta('slug') == name]
+        if not results:
+            utils.LOGGER.warning("Cannot resolve path request for slug: {0}".format(name))
+        else:
+            if len(results) > 1:
+                utils.LOGGER.warning('Ambiguous path request for slug: {0}'.format(name))
+            return [_f for _f in results[0].translated_source_path(lang).split('/')]
+
     def filename_path(self, name, lang):
         """Link to post or page by source filename.