cr: Add support for GN build file generation

To use, invoke cr init with --generator gn:

$ cr init -o out_linux/Debug --generator gn
$ cr build ...
$ cr run ...
$ etc.

You can also pass in additional arguments:

$ cr init -o out_linux/Debug --generator gn -s GN_ARG_foo=bar

Note that gn args works normally, although you need to specify the out directory manually:

$ gn args out_linux/Debug

Review URL: https://codereview.chromium.org/1095613002

Cr-Commit-Position: refs/heads/master@{#325664}

tools/cr/cr/actions/gn.py

@@ -0,0 +1,72 @@
+# Copyright 2015 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 module to add gn support to cr."""
+
+import cr
+import shlex
+import os
+
+GN_ARG_PREFIX = 'GN_ARG_'
+
+
+class GnPrepareOut(cr.PrepareOut):
+  """A prepare action that runs gn whenever you select an output directory."""
+
+  ACTIVE = cr.Config.From(
+      GN_ARG_is_component_build='true',
+  )
+
+  @property
+  def enabled(self):
+    # Disabled on Android for now.
+    return not cr.AndroidPlatform.GetInstance().is_active
+
+  def UpdateContext(self):
+    # Collapse GN_ARGS from all GN_ARG prefixes
+    gn_args = cr.context.Find('GN_ARGS') or ''
+    for key, value in cr.context.exported.items():
+      if key.startswith(GN_ARG_PREFIX):
+        gn_args += ' %s=%s' % (key[len(GN_ARG_PREFIX):], value)
+
+    gn_args += (' is_debug=%s' %
+        'true' if cr.context['CR_BUILDTYPE'] == 'Debug' else 'false')
+
+    cr.context['GN_ARGS'] = gn_args.strip()
+    if cr.context.verbose >= 1:
+      print cr.context.Substitute('GN_ARGS = {GN_ARGS}')
+
+  def Prepare(self):
+    if cr.context.verbose >= 1:
+      print cr.context.Substitute('Invoking gn with {GN_ARGS}')
+
+    args_file = os.path.join(cr.context['CR_SRC'],
+                             cr.context['CR_OUT_FULL'],
+                             'args.gn')
+    args = {}
+    for arg in shlex.split(cr.context['GN_ARGS']):
+      key, value = arg.split('=', 1)
+      args[key] = value
+
+    # Override any existing settings.
+    arg_lines = []
+    if os.path.exists(args_file):
+      with open(args_file) as f:
+        for line in f:
+          key = line.split('=', 1)[0].strip()
+          if key not in args:
+            arg_lines.append(line.strip())
+
+    # Append new settings.
+    for key, value in args.items():
+      arg_lines.append('%s = %s' % (key, value))
+
+    with open(args_file, 'w') as f:
+      f.write('\n'.join(arg_lines) + '\n')
+
+    cr.Host.Execute(
+        'gn',
+        'gen',
+        '{CR_OUT_FULL}',
+    )

tools/cr/cr/actions/gyp.py

@@ -12,7 +12,7 @@
 class GypPrepareOut(cr.PrepareOut):
   """A prepare action that runs gyp whenever you select an output directory."""
 
-  ENABLED = cr.Config.From(
+  ACTIVE = cr.Config.From(
       GYP_GENERATORS='ninja',
       GYP_GENERATOR_FLAGS='output_dir={CR_OUT_BASE} config={CR_BUILDTYPE}',
       GYP_DEF_target_arch='{CR_ENVSETUP_ARCH}',

tools/cr/cr/base/android.py

@@ -38,7 +38,8 @@ class AndroidPlatform(cr.Platform):
           '{CR_SRC}', 'build', 'android', 'test_runner.py'),
       CR_ADB_GDB=os.path.join('{CR_SRC}', 'build', 'android', 'adb_gdb'),
       CR_DEFAULT_TARGET='chrome_shell',
-      GYP_DEF_OS='android'
+      GYP_DEF_OS='android',
+      GN_ARG_os='"android"'
   )
 
   def __init__(self):

tools/cr/cr/commands/init.py

@@ -11,8 +11,12 @@
 # The set of variables to store in the per output configuration.
 OUT_CONFIG_VARS = [
     'CR_VERSION',
-    cr.Platform.SELECTOR, cr.BuildType.SELECTOR, cr.Arch.SELECTOR,
-    'CR_OUT_BASE', 'CR_OUT_FULL',
+    cr.Platform.SELECTOR,
+    cr.BuildType.SELECTOR,
+    cr.Arch.SELECTOR,
+    cr.PrepareOut.SELECTOR,
+    'CR_OUT_BASE',
+    'CR_OUT_FULL',
 ]
 
 
@@ -43,6 +47,7 @@ def AddArguments(self, subparsers):
     cr.BuildType.AddArguments(parser)
     cr.Arch.AddArguments(parser)
     cr.SelectCommand.AddPrepareArguments(parser)
+    cr.PrepareOut.AddArguments(parser)
     parser.add_argument(
         '-s', '--set', dest='_settings', metavar='settings',
         action='append',
@@ -85,11 +90,15 @@ def EarlyArgProcessing(self):
             print 'Matched all of', ','.join(matches)
           exit(1)
         platform = matches[0]
+      generator = cr.context.args.CR_GENERATOR
+      if not generator:
+        generator = 'gyp'
       cr.context.derived.Set(
           CR_OUT_FULL=out,
           CR_OUT_BASE=base,
           CR_PLATFORM=platform,
           CR_BUILDTYPE=buildtype,
+          CR_GENERATOR=generator
       )
     if not 'CR_OUT_BASE' in cr.context:
       cr.context.derived['CR_OUT_BASE'] = 'out_{CR_PLATFORM}'

tools/cr/cr/commands/prepare.py

@@ -31,14 +31,12 @@ def Run(self):
 
   @classmethod
   def UpdateContext(cls):
-    for preparation in PrepareOut.Plugins():
-      preparation.UpdateContext()
+    PrepareOut.GetActivePlugin().UpdateContext()
 
   @classmethod
   def Prepare(cls):
     cls.UpdateContext()
-    for preparation in PrepareOut.Plugins():
-      preparation.Prepare()
+    PrepareOut.GetActivePlugin().Prepare()
 
 
 class PrepareOut(cr.Plugin, cr.Plugin.Type):
@@ -47,6 +45,18 @@ class PrepareOut(cr.Plugin, cr.Plugin.Type):
   See PrepareCommand for details.
   """
 
+  SELECTOR = 'CR_GENERATOR'
+
+  @classmethod
+  def AddArguments(cls, parser):
+    parser.add_argument(
+        '--generator', dest=cls.SELECTOR,
+        choices=cls.Choices(),
+        default=None,
+        help=('Sets the build file generator to use. ' +
+              'Overrides %s.' % cls.SELECTOR)
+    )
+
   def UpdateContext(self):
     """Update the context if needed.