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# 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()
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