1 files changed, 73 insertions, 0 deletions
diff --git a/ka_factory.py b/ka_factory.py
new file mode 100644
index 0000000..21f50d4
--- /dev/null
+++ b/ka_factory.py
@@ -0,0 +1,73 @@
+# coding: UTF8
+# Copyright 2009 Thomas Jourdan
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+import random
+import ka_extensionpoint
+
+class LayerFactory(object):
+    """
+    inv: self.factory_keys is not None
+    """
+    def __init__(self, category):
+        """ LayerFactory is a singleton. 
+        Please call ka_factory.get_factory(category) to retrieve the instance.
+        """
+        self.category = category
+        self.factory_keys = ka_extensionpoint.list_extensions(self.category)
+        self.factory_keys = map(lambda x: x.replace(self.category + '_', ''), \
+                                self.factory_keys)
+
+    def count(self):
+        """
+        post: __return__ > 0
+        """
+        return len(self.factory_keys)
+
+    def keys(self):
+        """
+        """
+        return self.factory_keys
+
+    def create(self, factory_key, trunk):
+        """
+        pre: factory_key in self.factory_keys
+        post: __return__ is not None
+        """
+        return ka_extensionpoint.create(self.category + '_' + factory_key, trunk)
+
+    def create_random(self, key_filter, trunk):
+        """
+        pre: key_filter is not None
+        pre: len(key_filter) > 0
+        post: __return__ is not None
+        """
+        permitted = [x for x in self.factory_keys if x in key_filter]
+        return self.create(random.choice(permitted), trunk)
+
+_factory_index = {}
+
+def get_factory(category):
+    """
+    pre: category is not None
+    post: __return__ is not None
+    """
+#    global _factory_index
+#    if _factory_index is None:
+#        _factory_index = {}
+    if not _factory_index.has_key(category):
+        _factory_index[category] = LayerFactory(category)
+    return _factory_index[category]