Add depswriter scripts

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

bin/closure/source.py

@@ -0,0 +1,114 @@
+# Copyright 2009 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.
+
+
+"""Scans a source JS file for its provided and required namespaces.
+
+Simple class to scan a JavaScript file and express its dependencies.
+"""
+
+__author__ = 'nnaze@google.com'
+
+
+import re
+
+_BASE_REGEX_STRING = '^\s*goog\.%s\(\s*[\'"](.+)[\'"]\s*\)'
+_PROVIDE_REGEX = re.compile(_BASE_REGEX_STRING % 'provide')
+_REQUIRES_REGEX = re.compile(_BASE_REGEX_STRING % 'require')
+
+# This line identifies base.js and should match the line in that file.
+_GOOG_BASE_LINE = (
+    'var goog = goog || {}; // Identifies this file as the Closure base.')
+
+
+class Source(object):
+  """Scans a JavaScript source for its provided and required namespaces."""
+
+  # Matches a "/* ... */" comment.
+  # Note: We can't definitively distinguish a "/*" in a string literal without a
+  # state machine tokenizer. We'll assume that a line starting with whitespace
+  # and "/*" is a comment.
+  _COMMENT_REGEX = re.compile(
+      r"""
+      ^\s*   # Start of a new line and whitespace
+      /\*    # Opening "/*"
+      .*?    # Non greedy match of any characters (including newlines)
+      \*/    # Closing "*/""",
+      re.MULTILINE | re.DOTALL | re.VERBOSE)
+
+  def __init__(self, source):
+    """Initialize a source.
+
+    Args:
+      source: str, The JavaScript source.
+    """
+
+    self.provides = set()
+    self.requires = set()
+
+    self._source = source
+    self._ScanSource()
+
+  def __str__(self):
+    return 'Source %s' % self._path
+
+  def GetSource(self):
+    """Get the source as a string."""
+    return self._source
+
+  @classmethod
+  def _StripComments(cls, source):
+    return cls._COMMENT_REGEX.sub('', source)
+
+  def _ScanSource(self):
+    """Fill in provides and requires by scanning the source."""
+
+    source = self._StripComments(self.GetSource())
+
+    source_lines = source.splitlines()
+    for line in source_lines:
+      match = _PROVIDE_REGEX.match(line)
+      if match:
+        self.provides.add(match.group(1))
+      match = _REQUIRES_REGEX.match(line)
+      if match:
+        self.requires.add(match.group(1))
+
+    # Closure's base file implicitly provides 'goog'.
+    for line in source_lines:
+      if line == _GOOG_BASE_LINE:
+        if len(self.provides) or len(self.requires):
+          raise Exception(
+              'Base files should not provide or require namespaces.')
+        self.provides.add('goog')
+
+
+def GetFileContents(path):
+  """Get a file's contents as a string.
+
+  Args:
+    path: str, Path to file.
+
+  Returns:
+    str, Contents of file.
+
+  Raises:
+    IOError: An error occurred opening or reading the file.
+
+  """
+  fileobj = open(path)
+  try:
+    return fileobj.read()
+  finally:
+    fileobj.close()