Add depswriter scripts

Copied from http://closure-library.googlecode.com/git/closure/bin/build/

bin/closure/treescan.py

@@ -0,0 +1,78 @@
+#!/usr/bin/env python
+#
+# Copyright 2010 The Closure Library Authors. All Rights Reserved.
+#
+# 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.
+
+
+"""Shared utility functions for scanning directory trees."""
+
+import os
+import re
+
+
+__author__ = 'nnaze@google.com (Nathan Naze)'
+
+
+# Matches a .js file path.
+_JS_FILE_REGEX = re.compile(r'^.+\.js$')
+
+
+def ScanTreeForJsFiles(root):
+  """Scans a directory tree for JavaScript files.
+
+  Args:
+    root: str, Path to a root directory.
+
+  Returns:
+    An iterable of paths to JS files, relative to cwd.
+  """
+  return ScanTree(root, path_filter=_JS_FILE_REGEX)
+
+
+def ScanTree(root, path_filter=None, ignore_hidden=True):
+  """Scans a directory tree for files.
+
+  Args:
+    root: str, Path to a root directory.
+    path_filter: A regular expression filter.  If set, only paths matching
+      the path_filter are returned.
+    ignore_hidden: If True, do not follow or return hidden directories or files
+      (those starting with a '.' character).
+
+  Yields:
+    A string path to files, relative to cwd.
+  """
+
+  def OnError(os_error):
+    raise os_error
+
+  for dirpath, dirnames, filenames in os.walk(root, onerror=OnError):
+    # os.walk allows us to modify dirnames to prevent decent into particular
+    # directories.  Avoid hidden directories.
+    for dirname in dirnames:
+      if ignore_hidden and dirname.startswith('.'):
+        dirnames.remove(dirname)
+
+    for filename in filenames:
+
+      # nothing that starts with '.'
+      if ignore_hidden and filename.startswith('.'):
+        continue
+
+      fullpath = os.path.join(dirpath, filename)
+
+      if path_filter and not path_filter.match(fullpath):
+        continue
+
+      yield os.path.normpath(fullpath)