--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/templatetags/cache.py	Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,57 @@
+from django.template import Library, Node, TemplateSyntaxError
+from django.template import resolve_variable
+from django.core.cache import cache
+from django.utils.encoding import force_unicode
+
+register = Library()
+
+class CacheNode(Node):
+    def __init__(self, nodelist, expire_time, fragment_name, vary_on):
+        self.nodelist = nodelist
+        self.expire_time = expire_time
+        self.fragment_name = fragment_name
+        self.vary_on = vary_on
+
+    def render(self, context):
+        # Build a unicode key for this fragment and all vary-on's.
+        cache_key = u':'.join([self.fragment_name] + \
+            [force_unicode(resolve_variable(var, context)) for var in self.vary_on])
+        value = cache.get(cache_key)
+        if value is None:
+            value = self.nodelist.render(context)
+            cache.set(cache_key, value, self.expire_time)
+        return value
+
+def do_cache(parser, token):
+    """
+    This will cache the contents of a template fragment for a given amount
+    of time.
+
+    Usage::
+
+        {% load cache %}
+        {% cache [expire_time] [fragment_name] %}
+            .. some expensive processing ..
+        {% endcache %}
+
+    This tag also supports varying by a list of arguments::
+
+        {% load cache %}
+        {% cache [expire_time] [fragment_name] [var1] [var2] .. %}
+            .. some expensive processing ..
+        {% endcache %}
+
+    Each unique set of arguments will result in a unique cache entry.
+    """
+    nodelist = parser.parse(('endcache',))
+    parser.delete_first_token()
+    tokens = token.contents.split()
+    if len(tokens) < 3:
+        raise TemplateSyntaxError(u"'%r' tag requires at least 2 arguments." % tokens[0])
+    try:
+        expire_time = int(tokens[1])
+    except ValueError:
+        raise TemplateSyntaxError(u"First argument to '%r' must be an integer (got '%s')." % (tokens[0], tokens[1]))
+    return CacheNode(nodelist, expire_time, tokens[2], tokens[3:])
+
+register.tag('cache', do_cache)