[infra] Begin removing gyp

build/gypi_to_gn.py

-# Copyright 2014 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.
-
-"""Converts a given gypi file to a python scope and writes the result to stdout.
-
-It is assumed that the file contains a toplevel dictionary, and this script
-will return that dictionary as a GN "scope" (see example below). This script
-does not know anything about GYP and it will not expand variables or execute
-conditions.
-
-It will strip conditions blocks.
-
-A variables block at the top level will be flattened so that the variables
-appear in the root dictionary. This way they can be returned to the GN code.
-
-Say your_file.gypi looked like this:
-  {
-     'sources': [ 'a.cc', 'b.cc' ],
-     'defines': [ 'ENABLE_DOOM_MELON' ],
-  }
-
-You would call it like this:
-  gypi_values = exec_script("//build/gypi_to_gn.py",
-                            [ rebase_path("your_file.gypi") ],
-                            "scope",
-                            [ "your_file.gypi" ])
-
-Notes:
- - The rebase_path call converts the gypi file from being relative to the
-   current build file to being system absolute for calling the script, which
-   will have a different current directory than this file.
-
- - The "scope" parameter tells GN to interpret the result as a series of GN
-   variable assignments.
-
- - The last file argument to exec_script tells GN that the given file is a
-   dependency of the build so Ninja can automatically re-run GN if the file
-   changes.
-
-Read the values into a target like this:
-  component("mycomponent") {
-    sources = gypi_values.sources
-    defines = gypi_values.defines
-  }
-
-Sometimes your .gypi file will include paths relative to a different
-directory than the current .gn file. In this case, you can rebase them to
-be relative to the current directory.
-  sources = rebase_path(gypi_values.sources, ".",
-                        "//path/gypi/input/values/are/relative/to")
-
-This script will tolerate a 'variables' in the toplevel dictionary or not. If
-the toplevel dictionary just contains one item called 'variables', it will be
-collapsed away and the result will be the contents of that dictinoary. Some
-.gypi files are written with or without this, depending on how they expect to
-be embedded into a .gyp file.
-
-This script also has the ability to replace certain substrings in the input.
-Generally this is used to emulate GYP variable expansion. If you passed the
-argument "--replace=<(foo)=bar" then all instances of "<(foo)" in strings in
-the input will be replaced with "bar":
-
-  gypi_values = exec_script("//build/gypi_to_gn.py",
-                            [ rebase_path("your_file.gypi"),
-                              "--replace=<(foo)=bar"],
-                            "scope",
-                            [ "your_file.gypi" ])
-
-"""
-
-import gn_helpers
-from optparse import OptionParser
-import sys
-
-def LoadPythonDictionary(path):
-  file_string = open(path).read()
-  try:
-    file_data = eval(file_string, {'__builtins__': None}, None)
-  except SyntaxError, e:
-    e.filename = path
-    raise
-  except Exception, e:
-    raise Exception("Unexpected error while reading %s: %s" % (path, str(e)))
-
-  assert isinstance(file_data, dict), "%s does not eval to a dictionary" % path
-
-  # Flatten any variables to the top level.
-  if 'variables' in file_data:
-    file_data.update(file_data['variables'])
-    del file_data['variables']
-
-  # Strip any conditions.
-  if 'conditions' in file_data:
-    del file_data['conditions']
-  if 'target_conditions' in file_data:
-    del file_data['target_conditions']
-
-  # Strip targets in the toplevel, since some files define these and we can't
-  # slurp them in.
-  if 'targets' in file_data:
-    del file_data['targets']
-
-  return file_data
-
-
-def ReplaceSubstrings(values, search_for, replace_with):
-  """Recursively replaces substrings in a value.
-
-  Replaces all substrings of the "search_for" with "repace_with" for all
-  strings occurring in "values". This is done by recursively iterating into
-  lists as well as the keys and values of dictionaries."""
-  if isinstance(values, str):
-    return values.replace(search_for, replace_with)
-
-  if isinstance(values, list):
-    return [ReplaceSubstrings(v, search_for, replace_with) for v in values]
-
-  if isinstance(values, dict):
-    # For dictionaries, do the search for both the key and values.
-    result = {}
-    for key, value in values.items():
-      new_key = ReplaceSubstrings(key, search_for, replace_with)
-      new_value = ReplaceSubstrings(value, search_for, replace_with)
-      result[new_key] = new_value
-    return result
-
-  # Assume everything else is unchanged.
-  return values
-
-def main():
-  parser = OptionParser()
-  parser.add_option("-r", "--replace", action="append",
-    help="Replaces substrings. If passed a=b, replaces all substrs a with b.")
-  (options, args) = parser.parse_args()
-
-  if len(args) != 1:
-    raise Exception("Need one argument which is the .gypi file to read.")
-
-  data = LoadPythonDictionary(args[0])
-  if options.replace:
-    # Do replacements for all specified patterns.
-    for replace in options.replace:
-      split = replace.split('=')
-      # Allow "foo=" to replace with nothing.
-      if len(split) == 1:
-        split.append('')
-      assert len(split) == 2, "Replacement must be of the form 'key=value'."
-      data = ReplaceSubstrings(data, split[0], split[1])
-
-  # Sometimes .gypi files use the GYP syntax with percents at the end of the
-  # variable name (to indicate not to overwrite a previously-defined value):
-  #   'foo%': 'bar',
-  # Convert these to regular variables.
-  for key in data:
-    if len(key) > 1 and key[len(key) - 1] == '%':
-      data[key[:-1]] = data[key]
-      del data[key]
-
-  print gn_helpers.ToGNString(data)
-
-if __name__ == '__main__':
-  try:
-    main()
-  except Exception, e:
-    print str(e)
-    sys.exit(1)