third_party/closure_compiler/processor.py

   1 # Copyright 2014 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 """Process Chrome resources (HTML/CSS/JS) to handle <include> and <if> tags."""
   6
   7 from collections import defaultdict
   8 import re
   9 import os
  10
  11
  12 class LineNumber(object):
  13   """A simple wrapper to hold line information (e.g. file.js:32)."""
  14   def __init__(self, source_file, line_number):
  15     """
  16     Args:
  17       source_file: A file path (as a string).
  18       line_number: The line in |file| (as an integer).
  19     """
  20     self.file = source_file
  21     self.line_number = int(line_number)
  22
  23
  24 class FileCache(object):
  25   """An in-memory cache to speed up reading the same files over and over.
  26
  27   Usage:
  28     FileCache.read(path_to_file)
  29   """
  30
  31   _cache = defaultdict(str)
  32
  33   @classmethod
  34   def read(self, source_file):
  35     """Read a file and return it as a string.
  36
  37     Args:
  38       source_file: a file path (as a string) to read and return the contents.
  39
  40     Returns:
  41       The contents of |source_file| (as a string).
  42     """
  43     abs_file = os.path.abspath(source_file)
  44     self._cache[abs_file] = self._cache[abs_file] or open(abs_file, "r").read()
  45     return self._cache[abs_file]
  46
  47
  48 class Processor(object):
  49   """Processes resource files, inlining the contents of <include> tags, removing
  50   <if> tags, and retaining original line info.
  51
  52   For example
  53
  54     1: /* blah.js */
  55     2: <if expr="is_win">
  56     3: <include src="win.js">
  57     4: </if>
  58
  59   would be turned into:
  60
  61     1: /* blah.js */
  62     2:
  63     3: /* win.js */
  64     4: alert('Ew; Windows.');
  65     5:
  66   """
  67
  68   _IF_TAGS_REG = "</?if[^>]*?>"
  69   _INCLUDE_REG = "<include[^>]+src=['\"]([^>]*)['\"]>"
  70
  71   def __init__(self, source_file):
  72     """
  73     Args:
  74       source_file: A file path to process (as a string).
  75     """
  76     self.included_files = set()
  77     self._index = 0
  78     self._lines = self._get_file(source_file)
  79
  80     # Can't enumerate(self._lines) here because some lines are re-processed.
  81     while self._index < len(self._lines):
  82       current_line = self._lines[self._index]
  83       match = re.search(self._INCLUDE_REG, current_line[2])
  84       if match:
  85         file_dir = os.path.dirname(current_line[0])
  86         file_name = os.path.abspath(os.path.join(file_dir, match.group(1)))
  87         if file_name not in self.included_files:
  88           self._include_file(file_name)
  89           continue  # Stay on the same line.
  90         else:
  91           # Found a duplicate <include>. Ignore and insert a blank line to
  92           # preserve line numbers.
  93           self._lines[self._index] = self._lines[self._index][:2] + ("",)
  94       self._index += 1
  95
  96     for i, line in enumerate(self._lines):
  97       self._lines[i] = line[:2] + (re.sub(self._IF_TAGS_REG, "", line[2]),)
  98
  99     self.contents = "\n".join(l[2] for l in self._lines)
 100
 101   # Returns a list of tuples in the format: (file, line number, line contents).
 102   def _get_file(self, source_file):
 103     lines = FileCache.read(source_file).splitlines()
 104     return [(source_file, lnum + 1, line) for lnum, line in enumerate(lines)]
 105
 106   def _include_file(self, source_file):
 107     self.included_files.add(source_file)
 108     f = self._get_file(source_file)
 109     self._lines = self._lines[:self._index] + f + self._lines[self._index + 1:]
 110
 111   def get_file_from_line(self, line_number):
 112     """Get the original file and line number for an expanded file's line number.
 113
 114     Args:
 115       line_number: A processed file's line number (as an integer or string).
 116     """
 117     line_number = int(line_number) - 1
 118     return LineNumber(self._lines[line_number][0], self._lines[line_number][1])