Strip comments and whitespace from Javascript resources

tools/grit/grit/flatten_resource_runner.py

Index: tools/grit/grit/flatten_resource_runner.py
diff --git a/tools/grit/grit/flatten_resource_runner.py b/tools/grit/grit/flatten_resource_runner.py
new file mode 100755
index 0000000000000000000000000000000000000000..e5516b0e2f40005625534a751d565535e49bc62f
--- /dev/null
+++ b/tools/grit/grit/flatten_resource_runner.py
@@ -0,0 +1,92 @@
+#!/usr/bin/env python
+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+'''A resource flattener for removing <include ...> and <if ...> elements
+
+This script inlines <include...> elements and processes and removes
+<if...> blocks based on C-preprocessor style defines, hence removing
+illegal language elements from HTML, Javascript, or CSS source files.
+This allows them to be pre-processed by standard tools (e.g the Javascript
+Closure compiler) before using them to build resource files.
+
+Unlike the HTML flattener used by 'grit build' this does not flatten HTML
+script, stylesheet, or icon elements; since those are legal HTML.
+
+This script is not built as a grit tool, since it does not take a grd file
+as input. It does, however, make use of various grit scripts.
+'''
+
+import sys
+
+if sys.version_info < (2, 7, 0):
+  sys.stderr.write('python 2.7 or later is required run this script\n')
+  sys.exit(1)
+
+import argparse
+import os
+
+from grit.format import html_inline
+from grit.node import base
+from grit import util
+
+def Main(args):
+
+  def OutputFileType(string):
+    '''A type of argument that automatically opens a file, creating'''
+    '''the directory if necessary'''
+    try:
+      if not os.path.exists(os.path.dirname(string)):
+        os.makedirs(os.path.dirname(string))
+      return open(string, 'w')

[Lei Zhang, 2016/06/29 22:51:32]

Probably want 'wb' ?

[aberent, 2016/07/14 15:41:36]

Done.

+    except (IOError , OSError) as e:

[Lei Zhang, 2016/06/29 22:51:32]

nit: no space before comma

[aberent, 2016/07/14 15:41:36]

Done.

+      raise argparse.ArgumentTypeError("can't open '%s': %s" % (string, e))
+
+  parser = argparse.ArgumentParser(
+      'Flatten <include...> and <if...> elements in resource source files')
+  parser.add_argument('-D',
+                      dest='defs',
+                      metavar='NAME[=VAL]',
+                      help='''
+  Specify a C-preprocessor-like define NAME with optional
+  value VAL (defaults to 1) which will be used to control
+  conditional inclusion of resources.
+  ''',
+                      action='append',
+                      default=[])
+  parser.add_argument(
+      '-t',
+      dest='platform',
+      metavar='PLATFORM',
+      help='''Specifies the platform the build is targeting; defaults
+                      to the value of sys.platform. The value provided via this

[Lei Zhang, 2016/06/29 22:51:32]

nit: I don't have Python readability, so what do I know, but this indentation
looks odd.

[aberent, 2016/07/14 15:41:36]

I think I hit an odd corner in Eclipse's python formatting. Done.

+                      flag should match what sys.platform would report for your
+                      target platform; see grit.node.base.EvaluateCondition.
+                      ''',
+      default = sys.platform)
+  parser.add_argument('input',
+                      help='The input file',
+                      type=argparse.FileType('r'))
+  parser.add_argument('output',
+                      help='The output file',
+                      type=OutputFileType)
+  parsed = parser.parse_args(args)
+
+  defines = {}
+  for d in parsed.defs:
+    name, value = util.ParseDefine(d)
+    defines[name] = value
+
+  def EvaluateCondition(expression, defines=defines, platform=parsed.platform):
+    return base.Node.EvaluateExpression(expression, defines, platform, [])
+
+  with parsed.output as out:

[Lei Zhang, 2016/06/29 22:51:32]

Why not just parsed.output.write(...) ?

[aberent, 2016/07/14 15:41:36]

Done.

+    out.write(html_inline.InlineToString(parsed.input.name,
+                                         EvaluateCondition,
+                                         preprocess_only=True))
+
+  return 0
+
+if __name__ == '__main__':
+  sys.exit(Main(sys.argv[1:]))