Issue 5336 - Allow additional include, page, and template paths using CMS

cms/sources.py

Index: cms/sources.py
===================================================================
--- a/cms/sources.py
+++ b/cms/sources.py
@@ -298,8 +298,118 @@
                     result.append(relpath + filename)
                 elif os.path.isdir(path):
                     do_list(path, relpath + filename + '/')
         do_list(self.get_path(subdir), '')
         return result
 
     def get_cache_dir(self):
         return os.path.join(self._dir, 'cache')
+
+
+class MultiSource(Source):
+    """A source that combines the contents of multiple other sources."""
+
+    def __init__(self, base_sources):
+        self._bases = base_sources
+
+    @property
+    def version(self):
+        return self._bases[0].version
+
+    def get_cache_dir(self):
+        return self._bases[0].get_cache_dir()
+
+    def __enter__(self):
+        for base in self._bases:
+            base.__enter__()
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        return any(base.__exit__(exc_type, exc_value, tb)
+                   for base in self._bases)
+
+    def close(self):
+        for base in self._bases:
+            base.close()
+
+    def has_file(self, filename):
+        return any(base.has_file(filename) for base in self._bases)
+
+    def read_file(self, filename, binary=False):
+        for base in self._bases:
+            if base.has_file(filename):
+                return base.read_file(filename, binary)
+        raise KeyError('File not found {}'.format(filename))
+
+    def list_files(self, subdir):
+        return {f for base in self._bases for f in base.list_files(subdir)}
+
+
+def _memoize(func):
+    """Cache results of functions calls."""
+    memoized = {}
+
+    def wrapper(*args):
+        try:
+            return memoized[args]
+        except KeyError:
+            return memoized.setdefault(args, func(*args))
+    wrapper.cache_clear = memoized.clear
+    return wrapper
+
+
+def create_source(path, static=False, revision=None):

[Sebastian Noack, 2017/09/29 19:11:30]

Does it still make sense to call that argument "static"? Whether the output will
be statically generated or delivered on the fly is an implementation detail of
the calling code. Since now this flag is only used to turn on caching, why not
just calling it "cached"?

[Vasily Kuznetsov, 2017/10/02 11:11:56]

Yeah, you're right, now it would be more clear if it's just a caching flag.

Done.

+    """Create a source from path and optional revision.
+
+    `static` flag indicates that the website source under `path` can be assumed
+    to not change after the source was created and any changes can be safely
+    ignored.
+    - If `static` is `True`, no interim changes are expected and caching will
+      be used to optimize performance.
+    - If `static` is `False`, changes on the filesystem are expected and will
+      be reflected in the outputs of the calls. This mode can be used for live
+      preview.
+
+    If `revision` option is provided, the `path` is assumed to be pointing to a
+    Mercurial repository. In this case the source will return the content of
+    selected revision (using `MercurialSource`) instead of the content of the
+    directory. Note that any local changes will be ignored in this case.
+
+    If `settings.ini` in the source contains `[paths]` section with an
+    `additional-paths` key that contains the list of additional root folders,
+    `MultiSource` will be instantiated and its bases will be the original
+    source plus an additional source for each additional root folder.
+    `MultiSource` looks up files in its base sources in the order they are
+    provided, so the files in the additional folders will only be used if the
+    original source doesn't contain that file.
+    """
+    if revision is not None:
+        source = MercurialSource(path, revision)
+    else:
+        source = FileSource(path)
+
+    config = source.read_config()
+    try:
+        ap = config.get('paths', 'additional-paths').strip()
+        additional_paths = filter(None, ap.split())
+    except (ConfigParser.NoSectionError, ConfigParser.NoOptionError):
+        additional_paths = []
+
+    if additional_paths:
+        additional_sources = [
+            create_source(os.path.join(path, p))
+            for p in additional_paths
+        ]
+        source = MultiSource([source] + additional_sources)
+
+    if static:
+        for fname in [
+            'resolve_link',
+            'read_config',
+            'read_template',
+            'read_locale',
+            'read_include',
+            'exec_file',
+        ]:
+            setattr(source, fname, _memoize(getattr(source, fname)))
+
+    return source