Add cache decorator to util and use it for template._get_docs.

logya/template.py

@@ -6,6 +6,8 @@
 
 from jinja2 import Environment, FileSystemLoader, escape
 
+from logya.util import cache
+
 
 env = Environment(
     loader=FileSystemLoader('templates'),
@@ -59,7 +61,7 @@ def _filesource(root: Path, name: str, lines: int = None, raw: bool = False) ->
         return text
     return escape(text)
 
-
+@cache
 def _get_docs(L, url: str, sort_attr: str = 'created', sort_order: str = 'descending') -> list:
     docs = []
     # A collection index will only exist at the given URL if there is no content document with the same URL.

logya/util.py

@@ -20,6 +20,18 @@
 Paths = namedtuple('Paths', ['root', 'content', 'public', 'static', 'templates'])
 
 
+def cache(func):
+    """Decorator for caching function calls."""
+
+    mapping = {}
+    def f(*args, **kwargs):
+        key = str(args) + str(kwargs)
+        if key not in mapping:
+            mapping[key] = func(*args, **kwargs)
+        return mapping[key]
+    return f
+
+
 # FIXME function never called, except in tests
 def deduplicate(li: list, attr: str) -> list:
     """Return a list without duplicates, based on value of given attribute."""