dom/canvas/test/webgl-conf/checkout/closure-library/closure/bin/build/source.py

   1 # Copyright 2009 The Closure Library Authors. All Rights Reserved.
   2 #
   3 # Licensed under the Apache License, Version 2.0 (the "License");
   4 # you may not use this file except in compliance with the License.
   5 # You may obtain a copy of the License at
   6 #
   7 #      http://www.apache.org/licenses/LICENSE-2.0
   8 #
   9 # Unless required by applicable law or agreed to in writing, software
  10 # distributed under the License is distributed on an "AS-IS" BASIS,
  11 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 # See the License for the specific language governing permissions and
  13 # limitations under the License.
  14
  15
  16 """Scans a source JS file for its provided and required namespaces.
  17
  18 Simple class to scan a JavaScript file and express its dependencies.
  19 """
  20
  21 __author__ = 'nnaze@google.com'
  22
  23
  24 import re
  25
  26 _BASE_REGEX_STRING = r'^\s*goog\.%s\(\s*[\'"](.+)[\'"]\s*\)'
  27 _MODULE_REGEX = re.compile(_BASE_REGEX_STRING % 'module')
  28 _PROVIDE_REGEX = re.compile(_BASE_REGEX_STRING % 'provide')
  29
  30 _REQUIRE_REGEX_STRING = (r'^\s*(?:(?:var|let|const)\s+[a-zA-Z_$][a-zA-Z0-9$_]*'
  31                          r'\s*=\s*)?goog\.require\(\s*[\'"](.+)[\'"]\s*\)')
  32 _REQUIRES_REGEX = re.compile(_REQUIRE_REGEX_STRING)
  33
  34
  35 class Source(object):
  36   """Scans a JavaScript source for its provided and required namespaces."""
  37
  38   # Matches a "/* ... */" comment.
  39   # Note: We can't definitively distinguish a "/*" in a string literal without a
  40   # state machine tokenizer. We'll assume that a line starting with whitespace
  41   # and "/*" is a comment.
  42   _COMMENT_REGEX = re.compile(
  43       r"""
  44       ^\s*   # Start of a new line and whitespace
  45       /\*    # Opening "/*"
  46       .*?    # Non greedy match of any characters (including newlines)
  47       \*/    # Closing "*/""",
  48       re.MULTILINE | re.DOTALL | re.VERBOSE)
  49
  50   def __init__(self, source):
  51     """Initialize a source.
  52
  53     Args:
  54       source: str, The JavaScript source.
  55     """
  56
  57     self.provides = set()
  58     self.requires = set()
  59     self.is_goog_module = False
  60
  61     self._source = source
  62     self._ScanSource()
  63
  64   def GetSource(self):
  65     """Get the source as a string."""
  66     return self._source
  67
  68   @classmethod
  69   def _StripComments(cls, source):
  70     return cls._COMMENT_REGEX.sub('', source)
  71
  72   @classmethod
  73   def _HasProvideGoogFlag(cls, source):
  74     """Determines whether the @provideGoog flag is in a comment."""
  75     for comment_content in cls._COMMENT_REGEX.findall(source):
  76       if '@provideGoog' in comment_content:
  77         return True
  78
  79     return False
  80
  81   def _ScanSource(self):
  82     """Fill in provides and requires by scanning the source."""
  83
  84     stripped_source = self._StripComments(self.GetSource())
  85
  86     source_lines = stripped_source.splitlines()
  87     for line in source_lines:
  88       match = _PROVIDE_REGEX.match(line)
  89       if match:
  90         self.provides.add(match.group(1))
  91       match = _MODULE_REGEX.match(line)
  92       if match:
  93         self.provides.add(match.group(1))
  94         self.is_goog_module = True
  95       match = _REQUIRES_REGEX.match(line)
  96       if match:
  97         self.requires.add(match.group(1))
  98
  99     # Closure's base file implicitly provides 'goog'.
 100     # This is indicated with the @provideGoog flag.
 101     if self._HasProvideGoogFlag(self.GetSource()):
 102
 103       if len(self.provides) or len(self.requires):
 104         raise Exception(
 105             'Base file should not provide or require namespaces.')
 106
 107       self.provides.add('goog')
 108
 109
 110 def GetFileContents(path):
 111   """Get a file's contents as a string.
 112
 113   Args:
 114     path: str, Path to file.
 115
 116   Returns:
 117     str, Contents of file.
 118
 119   Raises:
 120     IOError: An error occurred opening or reading the file.
 121
 122   """
 123   fileobj = open(path)
 124   try:
 125     return fileobj.read()
 126   finally:
 127     fileobj.close()