--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/soc/logic/path_link_name.py	Sun Oct 12 00:08:54 2008 +0000
@@ -0,0 +1,103 @@
+#!/usr/bin/python2.5
+#
+# Copyright 2008 the Melange authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Path and link name manipulation functions.
+"""
+
+__authors__ = [
+  '"Todd Larsen" <tlarsen@google.com>',
+  ]
+
+
+import re
+
+
+# start with ASCII digit or lowercase
+#   (additional ASCII digit or lowercase
+#     -OR-
+#   underscore and ASCII digit or lowercase)
+#     zero or more of OR group
+LINKNAME_PATTERN_CORE = r'[0-9a-z](?:[0-9a-z]|_[0-9a-z])*'
+LINKNAME_ARG_PATTERN = r'(?P<link_name>%s)' % LINKNAME_PATTERN_CORE
+LINKNAME_PATTERN = r'^%s$' % LINKNAME_PATTERN_CORE
+LINKNAME_REGEX = re.compile(LINKNAME_PATTERN)
+
+# partial path is multiple link_name chunks,
+#   each separated by a trailing /
+#     (at least 1)
+# followed by a single link_name with no trailing /
+PATH_LINKNAME_ARGS_PATTERN = (
+    r'(?P<partial_path>%(link_name)s(?:/%(link_name)s)*)/'
+     '(?P<link_name>%(link_name)s)' % {
+        'link_name': LINKNAME_PATTERN_CORE})
+
+PATH_LINKNAME_PATTERN = r'^%s$' % PATH_LINKNAME_ARGS_PATTERN
+PATH_LINKNAME_REGEX = re.compile(PATH_LINKNAME_PATTERN)
+
+
+def getPartsFromPath(path):
+  """Splits path string into partial_path and link_name.
+  
+  Returns:
+    {'partial_path': 'everything/but',
+     'link_name': 'link_name'}
+    or {} (empty dict) if string did not match PATH_LINKNAME_PATTERN.
+  """
+  path_link_name_match = PATH_LINKNAME_REGEX.match(path)
+  
+  if not path_link_name_match:
+    return {}
+
+  return path_link_name_match.groupdict()
+
+
+def combinePath(path_parts):
+  """Returns path components combined into a single string.
+  
+  Args:
+    path_parts: a single path string, or a list of path part strings,
+      or a nested list of path part strings (where the zeroeth element in
+      the list is itself a list); for example:
+        'a/complete/path/in/one/string'
+        ['some', 'path', 'parts']
+        [['path', 'parts', 'and', 'a'], 'link name']
+
+  Returns:
+    None if path_parts is False (None, empty string, etc.) or if
+    any list elements are False (an empty list, empty string, etc.);
+    otherwise, the combined string with the necessary separators.
+  """
+  if not path_parts:
+    # completely empty input, so return early
+    return None
+
+  if not isinstance(path_parts, (list, tuple)):
+    # a single path string, so just return it as-is (nothing to do)
+    return path_parts
+  
+  flattened_parts = []
+  
+  for part in path_parts:
+    if not part:
+      # encountered a "False" element, which invalidates everything else
+      return None    
+  
+    if isinstance(part, (list, tuple)):
+      flattened_parts.extend(part)
+    else:
+      flattened_parts.append(part)
+
+  return '/'.join(flattened_parts)