text: # Copyright (c) 2012 Google Inc. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  """
  This module contains classes that help to emulate xcodebuild behavior on top of
  other build systems, such as make and ninja.
  """
  
  import copy
  import gyp.common
  import os
  import os.path
  import re
  import shlex
  import subprocess
  import sys
  import tempfile
  from gyp.common import GypError
  
  # Populated lazily by XcodeVersion, for efficiency, and to fix an issue when
  # "xcodebuild" is called too quickly (it has been found to return incorrect
  # version number).
  XCODE_VERSION_CACHE = None
  
  # Populated lazily by GetXcodeArchsDefault, to an |XcodeArchsDefault| instance
  # corresponding to the installed version of Xcode.
  XCODE_ARCHS_DEFAULT_CACHE = None
  
  
  def XcodeArchsVariableMapping(archs, archs_including_64_bit=None):
    """Constructs a dictionary with expansion for $(ARCHS_STANDARD) variable,
    and optionally for $(ARCHS_STANDARD_INCLUDING_64_BIT)."""
    mapping = {'$(ARCHS_STANDARD)': archs}
    if archs_including_64_bit:
      mapping['$(ARCHS_STANDARD_INCLUDING_64_BIT)'] = archs_including_64_bit
    return mapping
  
  class XcodeArchsDefault(object):
    """A class to resolve ARCHS variable from xcode_settings, resolving Xcode
    macros and implementing filtering by VALID_ARCHS. The expansion of macros
    depends on the SDKROOT used ("macosx", "iphoneos", "iphonesimulator") and
    on the version of Xcode.
    """
  
    # Match variable like $(ARCHS_STANDARD).
    variable_pattern = re.compile(r'\$\([a-zA-Z_][a-zA-Z0-9_]*\)$')
  
    def __init__(self, default, mac, iphonesimulator, iphoneos):
      self._default = (default,)
      self._archs = {'mac': mac, 'ios': iphoneos, 'iossim': iphonesimulator}
  
    def _VariableMapping(self, sdkroot):
      """Returns the dictionary of variable mapping depending on the SDKROOT."""
      sdkroot = sdkroot.lower()
      if 'iphoneos' in sdkroot:
        return self._archs['ios']
      elif 'iphonesimulator' in sdkroot:
        return self._archs['iossim']
      else:
        return self._archs['mac']
  
    def _ExpandArchs(self, archs, sdkroot):
      """Expands variables references in ARCHS, and remove duplicates."""
      variable_mapping = self._VariableMapping(sdkroot)
      expanded_archs = []
      for arch in archs:
        if self.variable_pattern.match(arch):
          variable = arch
          try:
            variable_expansion = variable_mapping[variable]
            for arch in variable_expansion:
              if arch not in expanded_archs:
                expanded_archs.append(arch)
          except KeyError as e:
            print 'Warning: Ignoring unsupported variable "%s".' % variable
        elif arch not in expanded_archs:
          expanded_archs.append(arch)
      return expanded_archs
  
    def ActiveArchs(self, archs, valid_archs, sdkroot):
      """Expands variables references in ARCHS, and filter by VALID_ARCHS if it
      is defined (if not set, Xcode accept any value in ARCHS, otherwise, only
      values present in VALID_ARCHS are kept)."""
      expanded_archs = self._ExpandArchs(archs or self._default, sdkroot or '')
      if valid_archs:
        filtered_archs = []
        for arch in expanded_archs:
          if arch in valid_archs:
            filtered_archs.append(arch)
        expanded_archs = filtered_archs
      return expanded_archs
  
  
  def GetXcodeArchsDefault():
    """Returns the |XcodeArchsDefault| object to use to expand ARCHS for the
    installed version of Xcode. The default values used by Xcode for ARCHS
    and the expansion of the variables depends on the version of Xcode used.
  
    For all version anterior to Xcode 5.0 or posterior to Xcode 5.1 included
    uses $(ARCHS_STANDARD) if ARCHS is unset, while Xcode 5.0 to 5.0.2 uses
    $(ARCHS_STANDARD_INCLUDING_64_BIT). This variable was added to Xcode 5.0
    and deprecated with Xcode 5.1.
  
    For "macosx" SDKROOT, all version starting with Xcode 5.0 includes 64-bit
    architecture as part of $(ARCHS_STANDARD) and default to only building it.
  
    For "iphoneos" and "iphonesimulator" SDKROOT, 64-bit architectures are part
    of $(ARCHS_STANDARD_INCLUDING_64_BIT) from Xcode 5.0. From Xcode 5.1, they
    are also part of $(ARCHS_STANDARD).
  
    All thoses rules are coded in the construction of the |XcodeArchsDefault|
    object to use depending on the version of Xcode detected. The object is
    for performance reason."""
    global XCODE_ARCHS_DEFAULT_CACHE
    if XCODE_ARCHS_DEFAULT_CACHE:
      return XCODE_ARCHS_DEFAULT_CACHE
    xcode_version, _ = XcodeVersion()
    if xcode_version < '0500':
      XCODE_ARCHS_DEFAULT_CACHE = XcodeArchsDefault(
          '$(ARCHS_STANDARD)',
          XcodeArchsVariableMapping(['i386']),
          XcodeArchsVariableMapping(['i386']),
          XcodeArchsVariableMapping(['armv7']))
    elif xcode_version < '0510':
      XCODE_ARCHS_DEFAULT_CACHE = XcodeArchsDefault(
          '$(ARCHS_STANDARD_INCLUDING_64_BIT)',
          XcodeArchsVariableMapping(['x86_64'], ['x86_64']),
          XcodeArchsVariableMapping(['i386'], ['i386', 'x86_64']),
          XcodeArchsVariableMapping(
              ['armv7', 'armv7s'],
              ['armv7', 'armv7s', 'arm64']))
    else:
      XCODE_ARCHS_DEFAULT_CACHE = XcodeArchsDefault(
          '$(ARCHS_STANDARD)',
          XcodeArchsVariableMapping(['x86_64'], ['x86_64']),
          XcodeArchsVariableMapping(['i386', 'x86_64'], ['i386', 'x86_64']),
          XcodeArchsVariableMapping(
              ['armv7', 'armv7s', 'arm64'],
              ['armv7', 'armv7s', 'arm64']))
    return XCODE_ARCHS_DEFAULT_CACHE
  
  
  class XcodeSettings(object):
    """A class that understands the gyp 'xcode_settings' object."""
  
    # Populated lazily by _SdkPath(). Shared by all XcodeSettings, so cached
    # at class-level for efficiency.
    _sdk_path_cache = {}
    _sdk_root_cache = {}
  
    # Populated lazily by GetExtraPlistItems(). Shared by all XcodeSettings, so
    # cached at class-level for efficiency.
    _plist_cache = {}
  
    # Populated lazily by GetIOSPostbuilds.  Shared by all XcodeSettings, so
    # cached at class-level for efficiency.
    _codesigning_key_cache = {}
  
    def __init__(self, spec):
      self.spec = spec
  
      self.isIOS = False
  
      # Per-target 'xcode_settings' are pushed down into configs earlier by gyp.
      # This means self.xcode_settings[config] always contains all settings
      # for that config -- the per-target settings as well. Settings that are
      # the same for all configs are implicitly per-target settings.
      self.xcode_settings = {}
      configs = spec['configurations']
      for configname, config in configs.iteritems():
        self.xcode_settings[configname] = config.get('xcode_settings', {})
        self._ConvertConditionalKeys(configname)
        if self.xcode_settings[configname].get('IPHONEOS_DEPLOYMENT_TARGET',
                                               None):
          self.isIOS = True
  
      # This is only non-None temporarily during the execution of some methods.
      self.configname = None
  
      # Used by _AdjustLibrary to match .a and .dylib entries in libraries.
      self.library_re = re.compile(r'^lib([^/]+)\.(a|dylib)$')
  
    def _ConvertConditionalKeys(self, configname):
      """Converts or warns on conditional keys.  Xcode supports conditional keys,
      such as CODE_SIGN_IDENTITY[sdk=iphoneos*].  This is a partial implementation
      with some keys converted while the rest force a warning."""
      settings = self.xcode_settings[configname]
      conditional_keys = [key for key in settings if key.endswith(']')]
      for key in conditional_keys:
        # If you need more, speak up at http://crbug.com/122592
        if key.endswith("[sdk=iphoneos*]"):
          if configname.endswith("iphoneos"):
            new_key = key.split("[")[0]
            settings[new_key] = settings[key]
        else:
          print 'Warning: Conditional keys not implemented, ignoring:', \
                ' '.join(conditional_keys)
        del settings[key]
  
    def _Settings(self):
      assert self.configname
      return self.xcode_settings[self.configname]
  
    def _Test(self, test_key, cond_key, default):
      return self._Settings().get(test_key, default) == cond_key
  
    def _Appendf(self, lst, test_key, format_str, default=None):
      if test_key in self._Settings():
        lst.append(format_str % str(self._Settings()[test_key]))
      elif default:
        lst.append(format_str % str(default))
  
    def _WarnUnimplemented(self, test_key):
      if test_key in self._Settings():
        print 'Warning: Ignoring not yet implemented key "%s".' % test_key
  
    def IsBinaryOutputFormat(self, configname):
      default = "binary" if self.isIOS else "xml"
      format = self.xcode_settings[configname].get('INFOPLIST_OUTPUT_FORMAT',
                                                   default)
      return format == "binary"
  
    def _IsBundle(self):
      return int(self.spec.get('mac_bundle', 0)) != 0
  
    def _IsIosAppExtension(self):
      return int(self.spec.get('ios_app_extension', 0)) != 0
  
    def _IsIosWatchKitExtension(self):
      return int(self.spec.get('ios_watchkit_extension', 0)) != 0
  
    def _IsIosWatchApp(self):
      return int(self.spec.get('ios_watch_app', 0)) != 0
  
    def GetFrameworkVersion(self):
      """Returns the framework version of the current target. Only valid for
      bundles."""
      assert self._IsBundle()
      return self.GetPerTargetSetting('FRAMEWORK_VERSION', default='A')
  
    def GetWrapperExtension(self):
      """Returns the bundle extension (.app, .framework, .plugin, etc).  Only
      valid for bundles."""
      assert self._IsBundle()
      if self.spec['type'] in ('loadable_module', 'shared_library'):
        default_wrapper_extension = {
          'loadable_module': 'bundle',
          'shared_library': 'framework',
        }[self.spec['type']]
        wrapper_extension = self.GetPerTargetSetting(
            'WRAPPER_EXTENSION', default=default_wrapper_extension)
        return '.' + self.spec.get('product_extension', wrapper_extension)
      elif self.spec['type'] == 'executable':
        if self._IsIosAppExtension() or self._IsIosWatchKitExtension():
          return '.' + self.spec.get('product_extension', 'appex')
        else:
          return '.' + self.spec.get('product_extension', 'app')
      else:
        assert False, "Don't know extension for '%s', target '%s'" % (
            self.spec['type'], self.spec['target_name'])
  
    def GetProductName(self):
      """Returns PRODUCT_NAME."""
      return self.spec.get('product_name', self.spec['target_name'])
  
    def GetFullProductName(self):
      """Returns FULL_PRODUCT_NAME."""
      if self._IsBundle():
        return self.GetWrapperName()
      else:
        return self._GetStandaloneBinaryPath()
  
    def GetWrapperName(self):
      """Returns the directory name of the bundle represented by this target.
      Only valid for bundles."""
      assert self._IsBundle()
      return self.GetProductName() + self.GetWrapperExtension()
  
    def GetBundleContentsFolderPath(self):
      """Returns the qualified path to the bundle's contents folder. E.g.
      Chromium.app/Contents or Foo.bundle/Versions/A. Only valid for bundles."""
      if self.isIOS:
        return self.GetWrapperName()
      assert self._IsBundle()
      if self.spec['type'] == 'shared_library':
        return os.path.join(
            self.GetWrapperName(), 'Versions', self.GetFrameworkVersion())
      else:
        # loadable_modules have a 'Contents' folder like executables.
        return os.path.join(self.GetWrapperName(), 'Contents')
  
    def GetBundleResourceFolder(self):
      """Returns the qualified path to the bundle's resource folder. E.g.
      Chromium.app/Contents/Resources. Only valid for bundles."""
      assert self._IsBundle()
      if self.isIOS:
        return self.GetBundleContentsFolderPath()
      return os.path.join(self.GetBundleContentsFolderPath(), 'Resources')
  
    def GetBundlePlistPath(self):
      """Returns the qualified path to the bundle's plist file. E.g.
      Chromium.app/Contents/Info.plist. Only valid for bundles."""
      assert self._IsBundle()
      if self.spec['type'] in ('executable', 'loadable_module'):
        return os.path.join(self.GetBundleContentsFolderPath(), 'Info.plist')
      else:
        return os.path.join(self.GetBundleContentsFolderPath(),
                            'Resources', 'Info.plist')
  
    def GetProductType(self):
      """Returns the PRODUCT_TYPE of this target."""
      if self._IsIosAppExtension():
        assert self._IsBundle(), ('ios_app_extension flag requires mac_bundle '
            '(target %s)' % self.spec['target_name'])
        return 'com.apple.product-type.app-extension'
      if self._IsIosWatchKitExtension():
        assert self._IsBundle(), ('ios_watchkit_extension flag requires '
            'mac_bundle (target %s)' % self.spec['target_name'])
        return 'com.apple.product-type.watchkit-extension'
      if self._IsIosWatchApp():
        assert self._IsBundle(), ('ios_watch_app flag requires mac_bundle '
            '(target %s)' % self.spec['target_name'])
        return 'com.apple.product-type.application.watchapp'
      if self._IsBundle():
        return {
          'executable': 'com.apple.product-type.application',
          'loadable_module': 'com.apple.product-type.bundle',
          'shared_library': 'com.apple.product-type.framework',
        }[self.spec['type']]
      else:
        return {
          'executable': 'com.apple.product-type.tool',
          'loadable_module': 'com.apple.product-type.library.dynamic',
          'shared_library': 'com.apple.product-type.library.dynamic',
          'static_library': 'com.apple.product-type.library.static',
        }[self.spec['type']]
  
    def GetMachOType(self):
      """Returns the MACH_O_TYPE of this target."""
      # Weird, but matches Xcode.
      if not self._IsBundle() and self.spec['type'] == 'executable':
        return ''
      return {
        'executable': 'mh_execute',
        'static_library': 'staticlib',
        'shared_library': 'mh_dylib',
        'loadable_module': 'mh_bundle',
      }[self.spec['type']]
  
    def _GetBundleBinaryPath(self):
      """Returns the name of the bundle binary of by this target.
      E.g. Chromium.app/Contents/MacOS/Chromium. Only valid for bundles."""
      assert self._IsBundle()
      if self.spec['type'] in ('shared_library') or self.isIOS:
        path = self.GetBundleContentsFolderPath()
      elif self.spec['type'] in ('executable', 'loadable_module'):
        path = os.path.join(self.GetBundleContentsFolderPath(), 'MacOS')
      return os.path.join(path, self.GetExecutableName())
  
    def _GetStandaloneExecutableSuffix(self):
      if 'product_extension' in self.spec:
        return '.' + self.spec['product_extension']
      return {
        'executable': '',
        'static_library': '.a',
        'shared_library': '.dylib',
        'loadable_module': '.so',
      }[self.spec['type']]
  
    def _GetStandaloneExecutablePrefix(self):
      return self.spec.get('product_prefix', {
        'executable': '',
        'static_library': 'lib',
        'shared_library': 'lib',
        # Non-bundled loadable_modules are called foo.so for some reason
        # (that is, .so and no prefix) with the xcode build -- match that.
        'loadable_module': '',
      }[self.spec['type']])
  
    def _GetStandaloneBinaryPath(self):
      """Returns the name of the non-bundle binary represented by this target.
      E.g. hello_world. Only valid for non-bundles."""
      assert not self._IsBundle()
      assert self.spec['type'] in (
          'executable', 'shared_library', 'static_library', 'loadable_module'), (
          'Unexpected type %s' % self.spec['type'])
      target = self.spec['target_name']
      if self.spec['type'] == 'static_library':
        if target[:3] == 'lib':
          target = target[3:]
      elif self.spec['type'] in ('loadable_module', 'shared_library'):
        if target[:3] == 'lib':
          target = target[3:]
  
      target_prefix = self._GetStandaloneExecutablePrefix()
      target = self.spec.get('product_name', target)
      target_ext = self._GetStandaloneExecutableSuffix()
      return target_prefix + target + target_ext
  
    def GetExecutableName(self):
      """Returns the executable name of the bundle represented by this target.
      E.g. Chromium."""
      if self._IsBundle():
        return self.spec.get('product_name', self.spec['target_name'])
      else:
        return self._GetStandaloneBinaryPath()
  
    def GetExecutablePath(self):
      """Returns the directory name of the bundle represented by this target. E.g.
      Chromium.app/Contents/MacOS/Chromium."""
      if self._IsBundle():
        return self._GetBundleBinaryPath()
      else:
        return self._GetStandaloneBinaryPath()
  
    def GetActiveArchs(self, configname):
      """Returns the architectures this target should be built for."""
      config_settings = self.xcode_settings[configname]
      xcode_archs_default = GetXcodeArchsDefault()
      return xcode_archs_default.ActiveArchs(
          config_settings.get('ARCHS'),
          config_settings.get('VALID_ARCHS'),
          config_settings.get('SDKROOT'))
  
    def _GetSdkVersionInfoItem(self, sdk, infoitem):
      # xcodebuild requires Xcode and can't run on Command Line Tools-only
      # systems from 10.7 onward.
      # Since the CLT has no SDK paths anyway, returning None is the
      # most sensible route and should still do the right thing.
      try:
        return GetStdout(['xcodebuild', '-version', '-sdk', sdk, infoitem])
      except:
        pass
  
    def _SdkRoot(self, configname):
      if configname is None:
        configname = self.configname
      return self.GetPerConfigSetting('SDKROOT', configname, default='')
  
    def _SdkPath(self, configname=None):
      sdk_root = self._SdkRoot(configname)
      if sdk_root.startswith('/'):
        return sdk_root
      return self._XcodeSdkPath(sdk_root)
  
    def _XcodeSdkPath(self, sdk_root):
      if sdk_root not in XcodeSettings._sdk_path_cache:
        sdk_path = self._GetSdkVersionInfoItem(sdk_root, 'Path')
        XcodeSettings._sdk_path_cache[sdk_root] = sdk_path
        if sdk_root:
          XcodeSettings._sdk_root_cache[sdk_path] = sdk_root
      return XcodeSettings._sdk_path_cache[sdk_root]
  
    def _AppendPlatformVersionMinFlags(self, lst):
      self._Appendf(lst, 'MACOSX_DEPLOYMENT_TARGET', '-mmacosx-version-min=%s')
      if 'IPHONEOS_DEPLOYMENT_TARGET' in self._Settings():
        # TODO: Implement this better?
        sdk_path_basename = os.path.basename(self._SdkPath())
        if sdk_path_basename.lower().startswith('iphonesimulator'):
          self._Appendf(lst, 'IPHONEOS_DEPLOYMENT_TARGET',
                        '-mios-simulator-version-min=%s')
        else:
          self._Appendf(lst, 'IPHONEOS_DEPLOYMENT_TARGET',
                        '-miphoneos-version-min=%s')
  
    def GetCflags(self, configname, arch=None):
      """Returns flags that need to be added to .c, .cc, .m, and .mm
      compilations."""
      # This functions (and the similar ones below) do not offer complete
      # emulation of all xcode_settings keys. They're implemented on demand.
  
      self.configname = configname
      cflags = []
  
      sdk_root = self._SdkPath()
      if 'SDKROOT' in self._Settings() and sdk_root:
        cflags.append('-isysroot %s' % sdk_root)
  
      if self._Test('CLANG_WARN_CONSTANT_CONVERSION', 'YES', default='NO'):
        cflags.append('-Wconstant-conversion')
  
      if self._Test('GCC_CHAR_IS_UNSIGNED_CHAR', 'YES', default='NO'):
        cflags.append('-funsigned-char')
  
      if self._Test('GCC_CW_ASM_SYNTAX', 'YES', default='YES'):
        cflags.append('-fasm-blocks')
  
      if 'GCC_DYNAMIC_NO_PIC' in self._Settings():
        if self._Settings()['GCC_DYNAMIC_NO_PIC'] == 'YES':
          cflags.append('-mdynamic-no-pic')
      else:
        pass
        # TODO: In this case, it depends on the target. xcode passes
        # mdynamic-no-pic by default for executable and possibly static lib
        # according to mento
  
      if self._Test('GCC_ENABLE_PASCAL_STRINGS', 'YES', default='YES'):
        cflags.append('-mpascal-strings')
  
      self._Appendf(cflags, 'GCC_OPTIMIZATION_LEVEL', '-O%s', default='s')
  
      if self._Test('GCC_GENERATE_DEBUGGING_SYMBOLS', 'YES', default='YES'):
        dbg_format = self._Settings().get('DEBUG_INFORMATION_FORMAT', 'dwarf')
        if dbg_format == 'dwarf':
          cflags.append('-gdwarf-2')
        elif dbg_format == 'stabs':
          raise NotImplementedError('stabs debug format is not supported yet.')
        elif dbg_format == 'dwarf-with-dsym':
          cflags.append('-gdwarf-2')
        else:
          raise NotImplementedError('Unknown debug format %s' % dbg_format)
  
      if self._Settings().get('GCC_STRICT_ALIASING') == 'YES':
        cflags.append('-fstrict-aliasing')
      elif self._Settings().get('GCC_STRICT_ALIASING') == 'NO':
        cflags.append('-fno-strict-aliasing')
  
      if self._Test('GCC_SYMBOLS_PRIVATE_EXTERN', 'YES', default='NO'):
        cflags.append('-fvisibility=hidden')
  
      if self._Test('GCC_TREAT_WARNINGS_AS_ERRORS', 'YES', default='NO'):
        cflags.append('-Werror')
  
      if self._Test('GCC_WARN_ABOUT_MISSING_NEWLINE', 'YES', default='NO'):
        cflags.append('-Wnewline-eof')
  
      self._AppendPlatformVersionMinFlags(cflags)
  
      # TODO:
      if self._Test('COPY_PHASE_STRIP', 'YES', default='NO'):
        self._WarnUnimplemented('COPY_PHASE_STRIP')
      self._WarnUnimplemented('GCC_DEBUGGING_SYMBOLS')
      self._WarnUnimplemented('GCC_ENABLE_OBJC_EXCEPTIONS')
  
      # TODO: This is exported correctly, but assigning to it is not supported.
      self._WarnUnimplemented('MACH_O_TYPE')
      self._WarnUnimplemented('PRODUCT_TYPE')
  
      if arch is not None:
        archs = [arch]
      else:
        assert self.configname
        archs = self.GetActiveArchs(self.configname)
      if len(archs) != 1:
        # TODO: Supporting fat binaries will be annoying.
        self._WarnUnimplemented('ARCHS')
        archs = ['i386']
      cflags.append('-arch ' + archs[0])
  
      if archs[0] in ('i386', 'x86_64'):
        if self._Test('GCC_ENABLE_SSE3_EXTENSIONS', 'YES', default='NO'):
          cflags.append('-msse3')
        if self._Test('GCC_ENABLE_SUPPLEMENTAL_SSE3_INSTRUCTIONS', 'YES',
                      default='NO'):
          cflags.append('-mssse3')  # Note 3rd 's'.
        if self._Test('GCC_ENABLE_SSE41_EXTENSIONS', 'YES', default='NO'):
          cflags.append('-msse4.1')
        if self._Test('GCC_ENABLE_SSE42_EXTENSIONS', 'YES', default='NO'):
          cflags.append('-msse4.2')
  
      cflags += self._Settings().get('WARNING_CFLAGS', [])
  
      if sdk_root:
        framework_root = sdk_root
      else:
        framework_root = ''
      config = self.spec['configurations'][self.configname]
      framework_dirs = config.get('mac_framework_dirs', [])
      for directory in framework_dirs:
        cflags.append('-F' + directory.replace('$(SDKROOT)', framework_root))
  
      self.configname = None
      return cflags
  
    def GetCflagsC(self, configname):
      """Returns flags that need to be added to .c, and .m compilations."""
      self.configname = configname
      cflags_c = []
      if self._Settings().get('GCC_C_LANGUAGE_STANDARD', '') == 'ansi':
        cflags_c.append('-ansi')
      else:
        self._Appendf(cflags_c, 'GCC_C_LANGUAGE_STANDARD', '-std=%s')
      cflags_c += self._Settings().get('OTHER_CFLAGS', [])
      self.configname = None
      return cflags_c
  
    def GetCflagsCC(self, configname):
      """Returns flags that need to be added to .cc, and .mm compilations."""
      self.configname = configname
      cflags_cc = []
  
      clang_cxx_language_standard = self._Settings().get(
          'CLANG_CXX_LANGUAGE_STANDARD')
      # Note: Don't make c++0x to c++11 so that c++0x can be used with older
      # clangs that don't understand c++11 yet (like Xcode 4.2's).
      if clang_cxx_language_standard:
        cflags_cc.append('-std=%s' % clang_cxx_language_standard)
  
      self._Appendf(cflags_cc, 'CLANG_CXX_LIBRARY', '-stdlib=%s')
  
      if self._Test('GCC_ENABLE_CPP_RTTI', 'NO', default='YES'):
        cflags_cc.append('-fno-rtti')
      if self._Test('GCC_ENABLE_CPP_EXCEPTIONS', 'NO', default='YES'):
        cflags_cc.append('-fno-exceptions')
      if self._Test('GCC_INLINES_ARE_PRIVATE_EXTERN', 'YES', default='NO'):
        cflags_cc.append('-fvisibility-inlines-hidden')
      if self._Test('GCC_THREADSAFE_STATICS', 'NO', default='YES'):
        cflags_cc.append('-fno-threadsafe-statics')
      # Note: This flag is a no-op for clang, it only has an effect for gcc.
      if self._Test('GCC_WARN_ABOUT_INVALID_OFFSETOF_MACRO', 'NO', default='YES'):
        cflags_cc.append('-Wno-invalid-offsetof')
  
      other_ccflags = []
  
      for flag in self._Settings().get('OTHER_CPLUSPLUSFLAGS', ['$(inherited)']):
        # TODO: More general variable expansion. Missing in many other places too.
        if flag in ('$inherited', '$(inherited)', '${inherited}'):
          flag = '$OTHER_CFLAGS'
        if flag in ('$OTHER_CFLAGS', '$(OTHER_CFLAGS)', '${OTHER_CFLAGS}'):
          other_ccflags += self._Settings().get('OTHER_CFLAGS', [])
        else:
          other_ccflags.append(flag)
      cflags_cc += other_ccflags
  
      self.configname = None
      return cflags_cc
  
    def _AddObjectiveCGarbageCollectionFlags(self, flags):
      gc_policy = self._Settings().get('GCC_ENABLE_OBJC_GC', 'unsupported')
      if gc_policy == 'supported':
        flags.append('-fobjc-gc')
      elif gc_policy == 'required':
        flags.append('-fobjc-gc-only')
  
    def _AddObjectiveCARCFlags(self, flags):
      if self._Test('CLANG_ENABLE_OBJC_ARC', 'YES', default='NO'):
        flags.append('-fobjc-arc')
  
    def _AddObjectiveCMissingPropertySynthesisFlags(self, flags):
      if self._Test('CLANG_WARN_OBJC_MISSING_PROPERTY_SYNTHESIS',
                    'YES', default='NO'):
        flags.append('-Wobjc-missing-property-synthesis')
  
    def GetCflagsObjC(self, configname):
      """Returns flags that need to be added to .m compilations."""
      self.configname = configname
      cflags_objc = []
      self._AddObjectiveCGarbageCollectionFlags(cflags_objc)
      self._AddObjectiveCARCFlags(cflags_objc)
      self._AddObjectiveCMissingPropertySynthesisFlags(cflags_objc)
      self.configname = None
      return cflags_objc
  
    def GetCflagsObjCC(self, configname):
      """Returns flags that need to be added to .mm compilations."""
      self.configname = configname
      cflags_objcc = []
      self._AddObjectiveCGarbageCollectionFlags(cflags_objcc)
      self._AddObjectiveCARCFlags(cflags_objcc)
      self._AddObjectiveCMissingPropertySynthesisFlags(cflags_objcc)
      if self._Test('GCC_OBJC_CALL_CXX_CDTORS', 'YES', default='NO'):
        cflags_objcc.append('-fobjc-call-cxx-cdtors')
      self.configname = None
      return cflags_objcc
  
    def GetInstallNameBase(self):
      """Return DYLIB_INSTALL_NAME_BASE for this target."""
      # Xcode sets this for shared_libraries, and for nonbundled loadable_modules.
      if (self.spec['type'] != 'shared_library' and
          (self.spec['type'] != 'loadable_module' or self._IsBundle())):
        return None
      install_base = self.GetPerTargetSetting(
          'DYLIB_INSTALL_NAME_BASE',
          default='/Library/Frameworks' if self._IsBundle() else '/usr/local/lib')
      return install_base
  
    def _StandardizePath(self, path):
      """Do :standardizepath processing for path."""
      # I'm not quite sure what :standardizepath does. Just call normpath(),
      # but don't let @executable_path/../foo collapse to foo.
      if '/' in path:
        prefix, rest = '', path
        if path.startswith('@'):
          prefix, rest = path.split('/', 1)
        rest = os.path.normpath(rest)  # :standardizepath
        path = os.path.join(prefix, rest)
      return path
  
    def GetInstallName(self):
      """Return LD_DYLIB_INSTALL_NAME for this target."""
      # Xcode sets this for shared_libraries, and for nonbundled loadable_modules.
      if (self.spec['type'] != 'shared_library' and
          (self.spec['type'] != 'loadable_module' or self._IsBundle())):
        return None
  
      default_install_name = \
          '$(DYLIB_INSTALL_NAME_BASE:standardizepath)/$(EXECUTABLE_PATH)'
      install_name = self.GetPerTargetSetting(
          'LD_DYLIB_INSTALL_NAME', default=default_install_name)
  
      # Hardcode support for the variables used in chromium for now, to
      # unblock people using the make build.
      if '$' in install_name:
        assert install_name in ('$(DYLIB_INSTALL_NAME_BASE:standardizepath)/'
            '$(WRAPPER_NAME)/$(PRODUCT_NAME)', default_install_name), (
            'Variables in LD_DYLIB_INSTALL_NAME are not generally supported '
            'yet in target \'%s\' (got \'%s\')' %
                (self.spec['target_name'], install_name))
  
        install_name = install_name.replace(
            '$(DYLIB_INSTALL_NAME_BASE:standardizepath)',
            self._StandardizePath(self.GetInstallNameBase()))
        if self._IsBundle():
          # These are only valid for bundles, hence the |if|.
          install_name = install_name.replace(
              '$(WRAPPER_NAME)', self.GetWrapperName())
          install_name = install_name.replace(
              '$(PRODUCT_NAME)', self.GetProductName())
        else:
          assert '$(WRAPPER_NAME)' not in install_name
          assert '$(PRODUCT_NAME)' not in install_name
  
        install_name = install_name.replace(
            '$(EXECUTABLE_PATH)', self.GetExecutablePath())
      return install_name
  
    def _MapLinkerFlagFilename(self, ldflag, gyp_to_build_path):
      """Checks if ldflag contains a filename and if so remaps it from
      gyp-directory-relative to build-directory-relative."""
      # This list is expanded on demand.
      # They get matched as:
      #   -exported_symbols_list file
      #   -Wl,exported_symbols_list file
      #   -Wl,exported_symbols_list,file
      LINKER_FILE = r'(\S+)'
      WORD = r'\S+'
      linker_flags = [
        ['-exported_symbols_list', LINKER_FILE],    # Needed for NaCl.
        ['-unexported_symbols_list', LINKER_FILE],
        ['-reexported_symbols_list', LINKER_FILE],
        ['-sectcreate', WORD, WORD, LINKER_FILE],   # Needed for remoting.
      ]
      for flag_pattern in linker_flags:
        regex = re.compile('(?:-Wl,)?' + '[ ,]'.join(flag_pattern))
        m = regex.match(ldflag)
        if m:
          ldflag = ldflag[:m.start(1)] + gyp_to_build_path(m.group(1)) + \
                   ldflag[m.end(1):]
      # Required for ffmpeg (no idea why they don't use LIBRARY_SEARCH_PATHS,
      # TODO(thakis): Update ffmpeg.gyp):
      if ldflag.startswith('-L'):
        ldflag = '-L' + gyp_to_build_path(ldflag[len('-L'):])
      return ldflag
  
    def GetLdflags(self, configname, product_dir, gyp_to_build_path, arch=None):
      """Returns flags that need to be passed to the linker.
  
      Args:
          configname: The name of the configuration to get ld flags for.
          product_dir: The directory where products such static and dynamic
              libraries are placed. This is added to the library search path.
          gyp_to_build_path: A function that converts paths relative to the
              current gyp file to paths relative to the build direcotry.
      """
      self.configname = configname
      ldflags = []
  
      # The xcode build is relative to a gyp file's directory, and OTHER_LDFLAGS
      # can contain entries that depend on this. Explicitly absolutify these.
      for ldflag in self._Settings().get('OTHER_LDFLAGS', []):
        ldflags.append(self._MapLinkerFlagFilename(ldflag, gyp_to_build_path))
  
      if self._Test('DEAD_CODE_STRIPPING', 'YES', default='NO'):
        ldflags.append('-Wl,-dead_strip')
  
      if self._Test('PREBINDING', 'YES', default='NO'):
        ldflags.append('-Wl,-prebind')
  
      self._Appendf(
          ldflags, 'DYLIB_COMPATIBILITY_VERSION', '-compatibility_version %s')
      self._Appendf(
          ldflags, 'DYLIB_CURRENT_VERSION', '-current_version %s')
  
      self._AppendPlatformVersionMinFlags(ldflags)
  
      if 'SDKROOT' in self._Settings() and self._SdkPath():
        ldflags.append('-isysroot ' + self._SdkPath())
  
      for library_path in self._Settings().get('LIBRARY_SEARCH_PATHS', []):
        ldflags.append('-L' + gyp_to_build_path(library_path))
  
      if 'ORDER_FILE' in self._Settings():
        ldflags.append('-Wl,-order_file ' +
                       '-Wl,' + gyp_to_build_path(
                                    self._Settings()['ORDER_FILE']))
  
      if arch is not None:
        archs = [arch]
      else:
        assert self.configname
        archs = self.GetActiveArchs(self.configname)
      if len(archs) != 1:
        # TODO: Supporting fat binaries will be annoying.
        self._WarnUnimplemented('ARCHS')
        archs = ['i386']
      ldflags.append('-arch ' + archs[0])
  
      # Xcode adds the product directory by default.
      ldflags.append('-L' + product_dir)
  
      install_name = self.GetInstallName()
      if install_name and self.spec['type'] != 'loadable_module':
        ldflags.append('-install_name ' + install_name.replace(' ', r'\ '))
  
      for rpath in self._Settings().get('LD_RUNPATH_SEARCH_PATHS', []):
        ldflags.append('-Wl,-rpath,' + rpath)
  
      sdk_root = self._SdkPath()
      if not sdk_root:
        sdk_root = ''
      config = self.spec['configurations'][self.configname]
      framework_dirs = config.get('mac_framework_dirs', [])
      for directory in framework_dirs:
        ldflags.append('-F' + directory.replace('$(SDKROOT)', sdk_root))
  
      is_extension = self._IsIosAppExtension() or self._IsIosWatchKitExtension()
      if sdk_root and is_extension:
        # Adds the link flags for extensions. These flags are common for all
        # extensions and provide loader and main function.
        # These flags reflect the compilation options used by xcode to compile
        # extensions.
        ldflags.append('-lpkstart')
        ldflags.append(sdk_root +
            '/System/Library/PrivateFrameworks/PlugInKit.framework/PlugInKit')
        ldflags.append('-fapplication-extension')
        ldflags.append('-Xlinker -rpath '
            '-Xlinker @executable_path/../../Frameworks')
  
      self._Appendf(ldflags, 'CLANG_CXX_LIBRARY', '-stdlib=%s')
  
      self.configname = None
      return ldflags
  
    def GetLibtoolflags(self, configname):
      """Returns flags that need to be passed to the static linker.
  
      Args:
          configname: The name of the configuration to get ld flags for.
      """
      self.configname = configname
      libtoolflags = []
  
      for libtoolflag in self._Settings().get('OTHER_LDFLAGS', []):
        libtoolflags.append(libtoolflag)
      # TODO(thakis): ARCHS?
  
      self.configname = None
      return libtoolflags
  
    def GetPerTargetSettings(self):
      """Gets a list of all the per-target settings. This will only fetch keys
      whose values are the same across all configurations."""
      first_pass = True
      result = {}
      for configname in sorted(self.xcode_settings.keys()):
        if first_pass:
          result = dict(self.xcode_settings[configname])
          first_pass = False
        else:
          for key, value in self.xcode_settings[configname].iteritems():
            if key not in result:
              continue
            elif result[key] != value:
              del result[key]
      return result
  
    def GetPerConfigSetting(self, setting, configname, default=None):
      if configname in self.xcode_settings:
        return self.xcode_settings[configname].get(setting, default)
      else:
        return self.GetPerTargetSetting(setting, default)
  
    def GetPerTargetSetting(self, setting, default=None):
      """Tries to get xcode_settings.setting from spec. Assumes that the setting
         has the same value in all configurations and throws otherwise."""
      is_first_pass = True
      result = None
      for configname in sorted(self.xcode_settings.keys()):
        if is_first_pass:
          result = self.xcode_settings[configname].get(setting, None)
          is_first_pass = False
        else:
          assert result == self.xcode_settings[configname].get(setting, None), (
              "Expected per-target setting for '%s', got per-config setting "
              "(target %s)" % (setting, self.spec['target_name']))
      if result is None:
        return default
      return result
  
    def _GetStripPostbuilds(self, configname, output_binary, quiet):
      """Returns a list of shell commands that contain the shell commands
      neccessary to strip this target's binary. These should be run as postbuilds
      before the actual postbuilds run."""
      self.configname = configname
  
      result = []
      if (self._Test('DEPLOYMENT_POSTPROCESSING', 'YES', default='NO') and
          self._Test('STRIP_INSTALLED_PRODUCT', 'YES', default='NO')):
  
        default_strip_style = 'debugging'
        if self.spec['type'] == 'loadable_module' and self._IsBundle():
          default_strip_style = 'non-global'
        elif self.spec['type'] == 'executable':
          default_strip_style = 'all'
  
        strip_style = self._Settings().get('STRIP_STYLE', default_strip_style)
        strip_flags = {
          'all': '',
          'non-global': '-x',
          'debugging': '-S',
        }[strip_style]
  
        explicit_strip_flags = self._Settings().get('STRIPFLAGS', '')
        if explicit_strip_flags:
          strip_flags += ' ' + _NormalizeEnvVarReferences(explicit_strip_flags)
  
        if not quiet:
          result.append('echo STRIP\\(%s\\)' % self.spec['target_name'])
        result.append('strip %s %s' % (strip_flags, output_binary))
  
      self.configname = None
      return result
  
    def _GetDebugInfoPostbuilds(self, configname, output, output_binary, quiet):
      """Returns a list of shell commands that contain the shell commands
      neccessary to massage this target's debug information. These should be run
      as postbuilds before the actual postbuilds run."""
      self.configname = configname
  
      # For static libraries, no dSYMs are created.
      result = []
      if (self._Test('GCC_GENERATE_DEBUGGING_SYMBOLS', 'YES', default='YES') and
          self._Test(
              'DEBUG_INFORMATION_FORMAT', 'dwarf-with-dsym', default='dwarf') and
          self.spec['type'] != 'static_library'):
        if not quiet:
          result.append('echo DSYMUTIL\\(%s\\)' % self.spec['target_name'])
        result.append('dsymutil %s -o %s' % (output_binary, output + '.dSYM'))
  
      self.configname = None
      return result
  
    def _GetTargetPostbuilds(self, configname, output, output_binary,
                             quiet=False):
      """Returns a list of shell commands that contain the shell commands
      to run as postbuilds for this target, before the actual postbuilds."""
      # dSYMs need to build before stripping happens.
      return (
          self._GetDebugInfoPostbuilds(configname, output, output_binary, quiet) +
          self._GetStripPostbuilds(configname, output_binary, quiet))
  
    def _GetIOSPostbuilds(self, configname, output_binary):
      """Return a shell command to codesign the iOS output binary so it can
      be deployed to a device.  This should be run as the very last step of the
      build."""
      if not (self.isIOS and self.spec['type'] == 'executable'):
        return []
  
      settings = self.xcode_settings[configname]
      key = self._GetIOSCodeSignIdentityKey(settings)
      if not key:
        return []
  
      # Warn for any unimplemented signing xcode keys.
      unimpl = ['OTHER_CODE_SIGN_FLAGS']
      unimpl = set(unimpl) & set(self.xcode_settings[configname].keys())
      if unimpl:
        print 'Warning: Some codesign keys not implemented, ignoring: %s' % (
            ', '.join(sorted(unimpl)))
  
      return ['%s code-sign-bundle "%s" "%s" "%s" "%s"' % (
          os.path.join('${TARGET_BUILD_DIR}', 'gyp-mac-tool'), key,
          settings.get('CODE_SIGN_RESOURCE_RULES_PATH', ''),
          settings.get('CODE_SIGN_ENTITLEMENTS', ''),
          settings.get('PROVISIONING_PROFILE', ''))
      ]
  
    def _GetIOSCodeSignIdentityKey(self, settings):
      identity = settings.get('CODE_SIGN_IDENTITY')
      if not identity:
        return None
      if identity not in XcodeSettings._codesigning_key_cache:
        output = subprocess.check_output(
            ['security', 'find-identity', '-p', 'codesigning', '-v'])
        for line in output.splitlines():
          if identity in line:
            fingerprint = line.split()[1]
            cache = XcodeSettings._codesigning_key_cache
            assert identity not in cache or fingerprint == cache[identity], (
                "Multiple codesigning fingerprints for identity: %s" % identity)
            XcodeSettings._codesigning_key_cache[identity] = fingerprint
      return XcodeSettings._codesigning_key_cache.get(identity, '')
  
    def AddImplicitPostbuilds(self, configname, output, output_binary,
                              postbuilds=[], quiet=False):
      """Returns a list of shell commands that should run before and after
      |postbuilds|."""
      assert output_binary is not None
      pre = self._GetTargetPostbuilds(configname, output, output_binary, quiet)
      post = self._GetIOSPostbuilds(configname, output_binary)
      return pre + postbuilds + post
  
    def _AdjustLibrary(self, library, config_name=None):
      if library.endswith('.framework'):
        l = '-framework ' + os.path.splitext(os.path.basename(library))[0]
      else:
        m = self.library_re.match(library)
        if m:
          l = '-l' + m.group(1)
        else:
          l = library
  
      sdk_root = self._SdkPath(config_name)
      if not sdk_root:
        sdk_root = ''
      return l.replace('$(SDKROOT)', sdk_root)
  
    def AdjustLibraries(self, libraries, config_name=None):
      """Transforms entries like 'Cocoa.framework' in libraries into entries like
      '-framework Cocoa', 'libcrypto.dylib' into '-lcrypto', etc.
      """
      libraries = [self._AdjustLibrary(library, config_name)
                   for library in libraries]
      return libraries
  
    def _BuildMachineOSBuild(self):
      return GetStdout(['sw_vers', '-buildVersion'])
  
    def _XcodeIOSDeviceFamily(self, configname):
      family = self.xcode_settings[configname].get('TARGETED_DEVICE_FAMILY', '1')
      return [int(x) for x in family.split(',')]
  
    def GetExtraPlistItems(self, configname=None):
      """Returns a dictionary with extra items to insert into Info.plist."""
      if configname not in XcodeSettings._plist_cache:
        cache = {}
        cache['BuildMachineOSBuild'] = self._BuildMachineOSBuild()
  
        xcode, xcode_build = XcodeVersion()
        cache['DTXcode'] = xcode
        cache['DTXcodeBuild'] = xcode_build
  
        sdk_root = self._SdkRoot(configname)
        if not sdk_root:
          sdk_root = self._DefaultSdkRoot()
        cache['DTSDKName'] = sdk_root
        if xcode >= '0430':
          cache['DTSDKBuild'] = self._GetSdkVersionInfoItem(
              sdk_root, 'ProductBuildVersion')
        else:
          cache['DTSDKBuild'] = cache['BuildMachineOSBuild']
  
        if self.isIOS:
          cache['DTPlatformName'] = cache['DTSDKName']
          if configname.endswith("iphoneos"):
            cache['DTPlatformVersion'] = self._GetSdkVersionInfoItem(
                sdk_root, 'ProductVersion')
            cache['CFBundleSupportedPlatforms'] = ['iPhoneOS']
          else:
            cache['CFBundleSupportedPlatforms'] = ['iPhoneSimulator']
        XcodeSettings._plist_cache[configname] = cache
  
      # Include extra plist items that are per-target, not per global
      # XcodeSettings.
      items = dict(XcodeSettings._plist_cache[configname])
      if self.isIOS:
        items['UIDeviceFamily'] = self._XcodeIOSDeviceFamily(configname)
      return items
  
    def _DefaultSdkRoot(self):
      """Returns the default SDKROOT to use.
  
      Prior to version 5.0.0, if SDKROOT was not explicitly set in the Xcode
      project, then the environment variable was empty. Starting with this
      version, Xcode uses the name of the newest SDK installed.
      """
      xcode_version, xcode_build = XcodeVersion()
      if xcode_version < '0500':
        return ''
      default_sdk_path = self._XcodeSdkPath('')
      default_sdk_root = XcodeSettings._sdk_root_cache.get(default_sdk_path)
      if default_sdk_root:
        return default_sdk_root
      try:
        all_sdks = GetStdout(['xcodebuild', '-showsdks'])
      except:
        # If xcodebuild fails, there will be no valid SDKs
        return ''
      for line in all_sdks.splitlines():
        items = line.split()
        if len(items) >= 3 and items[-2] == '-sdk':
          sdk_root = items[-1]
          sdk_path = self._XcodeSdkPath(sdk_root)
          if sdk_path == default_sdk_path:
            return sdk_root
      return ''
  
  
  class MacPrefixHeader(object):
    """A class that helps with emulating Xcode's GCC_PREFIX_HEADER feature.
  
    This feature consists of several pieces:
    * If GCC_PREFIX_HEADER is present, all compilations in that project get an
      additional |-include path_to_prefix_header| cflag.
    * If GCC_PRECOMPILE_PREFIX_HEADER is present too, then the prefix header is
      instead compiled, and all other compilations in the project get an
      additional |-include path_to_compiled_header| instead.
      + Compiled prefix headers have the extension gch. There is one gch file for
        every language used in the project (c, cc, m, mm), since gch files for
        different languages aren't compatible.
      + gch files themselves are built with the target's normal cflags, but they
        obviously don't get the |-include| flag. Instead, they need a -x flag that
        describes their language.
      + All o files in the target need to depend on the gch file, to make sure
        it's built before any o file is built.
  
    This class helps with some of these tasks, but it needs help from the build
    system for writing dependencies to the gch files, for writing build commands
    for the gch files, and for figuring out the location of the gch files.
    """
    def __init__(self, xcode_settings,
                 gyp_path_to_build_path, gyp_path_to_build_output):
      """If xcode_settings is None, all methods on this class are no-ops.
  
      Args:
          gyp_path_to_build_path: A function that takes a gyp-relative path,
              and returns a path relative to the build directory.
          gyp_path_to_build_output: A function that takes a gyp-relative path and
              a language code ('c', 'cc', 'm', or 'mm'), and that returns a path
              to where the output of precompiling that path for that language
              should be placed (without the trailing '.gch').
      """
      # This doesn't support per-configuration prefix headers. Good enough
      # for now.
      self.header = None
      self.compile_headers = False
      if xcode_settings:
        self.header = xcode_settings.GetPerTargetSetting('GCC_PREFIX_HEADER')
        self.compile_headers = xcode_settings.GetPerTargetSetting(
            'GCC_PRECOMPILE_PREFIX_HEADER', default='NO') != 'NO'
      self.compiled_headers = {}
      if self.header:
        if self.compile_headers:
          for lang in ['c', 'cc', 'm', 'mm']:
            self.compiled_headers[lang] = gyp_path_to_build_output(
                self.header, lang)
        self.header = gyp_path_to_build_path(self.header)
  
    def _CompiledHeader(self, lang, arch):
      assert self.compile_headers
      h = self.compiled_headers[lang]
      if arch:
        h += '.' + arch
      return h
  
    def GetInclude(self, lang, arch=None):
      """Gets the cflags to include the prefix header for language |lang|."""
      if self.compile_headers and lang in self.compiled_headers:
        return '-include %s' % self._CompiledHeader(lang, arch)
      elif self.header:
        return '-include %s' % self.header
      else:
        return ''
  
    def _Gch(self, lang, arch):
      """Returns the actual file name of the prefix header for language |lang|."""
      assert self.compile_headers
      return self._CompiledHeader(lang, arch) + '.gch'
  
    def GetObjDependencies(self, sources, objs, arch=None):
      """Given a list of source files and the corresponding object files, returns
      a list of (source, object, gch) tuples, where |gch| is the build-directory
      relative path to the gch file each object file depends on.  |compilable[i]|
      has to be the source file belonging to |objs[i]|."""
      if not self.header or not self.compile_headers:
        return []
  
      result = []
      for source, obj in zip(sources, objs):
        ext = os.path.splitext(source)[1]
        lang = {
          '.c': 'c',
          '.cpp': 'cc', '.cc': 'cc', '.cxx': 'cc',
          '.m': 'm',
          '.mm': 'mm',
        }.get(ext, None)
        if lang:
          result.append((source, obj, self._Gch(lang, arch)))
      return result
  
    def GetPchBuildCommands(self, arch=None):
      """Returns [(path_to_gch, language_flag, language, header)].
      |path_to_gch| and |header| are relative to the build directory.
      """
      if not self.header or not self.compile_headers:
        return []
      return [
        (self._Gch('c', arch), '-x c-header', 'c', self.header),
        (self._Gch('cc', arch), '-x c++-header', 'cc', self.header),
        (self._Gch('m', arch), '-x objective-c-header', 'm', self.header),
        (self._Gch('mm', arch), '-x objective-c++-header', 'mm', self.header),
      ]
  
  
  def XcodeVersion():
    """Returns a tuple of version and build version of installed Xcode."""
    # `xcodebuild -version` output looks like
    #    Xcode 4.6.3
    #    Build version 4H1503
    # or like
    #    Xcode 3.2.6
    #    Component versions: DevToolsCore-1809.0; DevToolsSupport-1806.0
    #    BuildVersion: 10M2518
    # Convert that to '0463', '4H1503'.
    global XCODE_VERSION_CACHE
    if XCODE_VERSION_CACHE:
      return XCODE_VERSION_CACHE
    try:
      version_list = GetStdout(['xcodebuild', '-version']).splitlines()
      # In some circumstances xcodebuild exits 0 but doesn't return
      # the right results; for example, a user on 10.7 or 10.8 with
      # a bogus path set via xcode-select
      # In that case this may be a CLT-only install so fall back to
      # checking that version.
      if len(version_list) < 2:
        raise GypError("xcodebuild returned unexpected results")
    except:
      version = CLTVersion()
      if version:
        version = re.match(r'(\d\.\d\.?\d*)', version).groups()[0]
      else:
        raise GypError("No Xcode or CLT version detected!")
      # The CLT has no build information, so we return an empty string.
      version_list = [version, '']
    version = version_list[0]
    build = version_list[-1]
    # Be careful to convert "4.2" to "0420":
    version = version.split()[-1].replace('.', '')
    version = (version + '0' * (3 - len(version))).zfill(4)
    if build:
      build = build.split()[-1]
    XCODE_VERSION_CACHE = (version, build)
    return XCODE_VERSION_CACHE
  
  
  # This function ported from the logic in Homebrew's CLT version check
  def CLTVersion():
    """Returns the version of command-line tools from pkgutil."""
    # pkgutil output looks like
    #   package-id: com.apple.pkg.CLTools_Executables
    #   version: 5.0.1.0.1.1382131676
    #   volume: /
    #   location: /
    #   install-time: 1382544035
    #   groups: com.apple.FindSystemFiles.pkg-group com.apple.DevToolsBoth.pkg-group com.apple.DevToolsNonRelocatableShared.pkg-group
    STANDALONE_PKG_ID = "com.apple.pkg.DeveloperToolsCLILeo"
    FROM_XCODE_PKG_ID = "com.apple.pkg.DeveloperToolsCLI"
    MAVERICKS_PKG_ID = "com.apple.pkg.CLTools_Executables"
  
    regex = re.compile('version: (?P<version>.+)')
    for key in [MAVERICKS_PKG_ID, STANDALONE_PKG_ID, FROM_XCODE_PKG_ID]:
      try:
        output = GetStdout(['/usr/sbin/pkgutil', '--pkg-info', key])
        return re.search(regex, output).groupdict()['version']
      except:
        continue
  
  
  def GetStdout(cmdlist):
    """Returns the content of standard output returned by invoking |cmdlist|.
    Raises |GypError| if the command return with a non-zero return code."""
    job = subprocess.Popen(cmdlist, stdout=subprocess.PIPE)
    out = job.communicate()[0]
    if job.returncode != 0:
      sys.stderr.write(out + '\n')
      raise GypError('Error %d running %s' % (job.returncode, cmdlist[0]))
    return out.rstrip('\n')
  
  
  def MergeGlobalXcodeSettingsToSpec(global_dict, spec):
    """Merges the global xcode_settings dictionary into each configuration of the
    target represented by spec. For keys that are both in the global and the local
    xcode_settings dict, the local key gets precendence.
    """
    # The xcode generator special-cases global xcode_settings and does something
    # that amounts to merging in the global xcode_settings into each local
    # xcode_settings dict.
    global_xcode_settings = global_dict.get('xcode_settings', {})
    for config in spec['configurations'].values():
      if 'xcode_settings' in config:
        new_settings = global_xcode_settings.copy()
        new_settings.update(config['xcode_settings'])
        config['xcode_settings'] = new_settings
  
  
  def IsMacBundle(flavor, spec):
    """Returns if |spec| should be treated as a bundle.
  
    Bundles are directories with a certain subdirectory structure, instead of
    just a single file. Bundle rules do not produce a binary but also package
    resources into that directory."""
    is_mac_bundle = (int(spec.get('mac_bundle', 0)) != 0 and flavor == 'mac')
    if is_mac_bundle:
      assert spec['type'] != 'none', (
          'mac_bundle targets cannot have type none (target "%s")' %
          spec['target_name'])
    return is_mac_bundle
  
  
  def GetMacBundleResources(product_dir, xcode_settings, resources):
    """Yields (output, resource) pairs for every resource in |resources|.
    Only call this for mac bundle targets.
  
    Args:
        product_dir: Path to the directory containing the output bundle,
            relative to the build directory.
        xcode_settings: The XcodeSettings of the current target.
        resources: A list of bundle resources, relative to the build directory.
    """
    dest = os.path.join(product_dir,
                        xcode_settings.GetBundleResourceFolder())
    for res in resources:
      output = dest
  
      # The make generator doesn't support it, so forbid it everywhere
      # to keep the generators more interchangable.
      assert ' ' not in res, (
        "Spaces in resource filenames not supported (%s)"  % res)
  
      # Split into (path,file).
      res_parts = os.path.split(res)
  
      # Now split the path into (prefix,maybe.lproj).
      lproj_parts = os.path.split(res_parts[0])
      # If the resource lives in a .lproj bundle, add that to the destination.
      if lproj_parts[1].endswith('.lproj'):
        output = os.path.join(output, lproj_parts[1])
  
      output = os.path.join(output, res_parts[1])
      # Compiled XIB files are referred to by .nib.
      if output.endswith('.xib'):
        output = os.path.splitext(output)[0] + '.nib'
      # Compiled storyboard files are referred to by .storyboardc.
      if output.endswith('.storyboard'):
        output = os.path.splitext(output)[0] + '.storyboardc'
  
      yield output, res
  
  
  def GetMacInfoPlist(product_dir, xcode_settings, gyp_path_to_build_path):
    """Returns (info_plist, dest_plist, defines, extra_env), where:
    * |info_plist| is the source plist path, relative to the
      build directory,
    * |dest_plist| is the destination plist path, relative to the
      build directory,
    * |defines| is a list of preprocessor defines (empty if the plist
      shouldn't be preprocessed,
    * |extra_env| is a dict of env variables that should be exported when
      invoking |mac_tool copy-info-plist|.
  
    Only call this for mac bundle targets.
  
    Args:
        product_dir: Path to the directory containing the output bundle,
            relative to the build directory.
        xcode_settings: The XcodeSettings of the current target.
        gyp_to_build_path: A function that converts paths relative to the
            current gyp file to paths relative to the build direcotry.
    """
    info_plist = xcode_settings.GetPerTargetSetting('INFOPLIST_FILE')
    if not info_plist:
      return None, None, [], {}
  
    # The make generator doesn't support it, so forbid it everywhere
    # to keep the generators more interchangable.
    assert ' ' not in info_plist, (
      "Spaces in Info.plist filenames not supported (%s)"  % info_plist)
  
    info_plist = gyp_path_to_build_path(info_plist)
  
    # If explicitly set to preprocess the plist, invoke the C preprocessor and
    # specify any defines as -D flags.
    if xcode_settings.GetPerTargetSetting(
        'INFOPLIST_PREPROCESS', default='NO') == 'YES':
      # Create an intermediate file based on the path.
      defines = shlex.split(xcode_settings.GetPerTargetSetting(
          'INFOPLIST_PREPROCESSOR_DEFINITIONS', default=''))
    else:
      defines = []
  
    dest_plist = os.path.join(product_dir, xcode_settings.GetBundlePlistPath())
    extra_env = xcode_settings.GetPerTargetSettings()
  
    return info_plist, dest_plist, defines, extra_env
  
  
  def _GetXcodeEnv(xcode_settings, built_products_dir, srcroot, configuration,
                  additional_settings=None):
    """Return the environment variables that Xcode would set. See
    http://developer.apple.com/library/mac/#documentation/DeveloperTools/Reference/XcodeBuildSettingRef/1-Build_Setting_Reference/build_setting_ref.html#//apple_ref/doc/uid/TP40003931-CH3-SW153
    for a full list.
  
    Args:
        xcode_settings: An XcodeSettings object. If this is None, this function
            returns an empty dict.
        built_products_dir: Absolute path to the built products dir.
        srcroot: Absolute path to the source root.
        configuration: The build configuration name.
        additional_settings: An optional dict with more values to add to the
            result.
    """
    if not xcode_settings: return {}
  
    # This function is considered a friend of XcodeSettings, so let it reach into
    # its implementation details.
    spec = xcode_settings.spec
  
    # These are filled in on a as-needed basis.
    env = {
      'BUILT_PRODUCTS_DIR' : built_products_dir,
      'CONFIGURATION' : configuration,
      'PRODUCT_NAME' : xcode_settings.GetProductName(),
      # See /Developer/Platforms/MacOSX.platform/Developer/Library/Xcode/Specifications/MacOSX\ Product\ Types.xcspec for FULL_PRODUCT_NAME
      'SRCROOT' : srcroot,
      'SOURCE_ROOT': '${SRCROOT}',
      # This is not true for static libraries, but currently the env is only
      # written for bundles:
      'TARGET_BUILD_DIR' : built_products_dir,
      'TEMP_DIR' : '${TMPDIR}',
    }
    if xcode_settings.GetPerConfigSetting('SDKROOT', configuration):
      env['SDKROOT'] = xcode_settings._SdkPath(configuration)
    else:
      env['SDKROOT'] = ''
  
    if spec['type'] in (
        'executable', 'static_library', 'shared_library', 'loadable_module'):
      env['EXECUTABLE_NAME'] = xcode_settings.GetExecutableName()
      env['EXECUTABLE_PATH'] = xcode_settings.GetExecutablePath()
      env['FULL_PRODUCT_NAME'] = xcode_settings.GetFullProductName()
      mach_o_type = xcode_settings.GetMachOType()
      if mach_o_type:
        env['MACH_O_TYPE'] = mach_o_type
      env['PRODUCT_TYPE'] = xcode_settings.GetProductType()
    if xcode_settings._IsBundle():
      env['CONTENTS_FOLDER_PATH'] = \
        xcode_settings.GetBundleContentsFolderPath()
      env['UNLOCALIZED_RESOURCES_FOLDER_PATH'] = \
          xcode_settings.GetBundleResourceFolder()
      env['INFOPLIST_PATH'] = xcode_settings.GetBundlePlistPath()
      env['WRAPPER_NAME'] = xcode_settings.GetWrapperName()
  
    install_name = xcode_settings.GetInstallName()
    if install_name:
      env['LD_DYLIB_INSTALL_NAME'] = install_name
    install_name_base = xcode_settings.GetInstallNameBase()
    if install_name_base:
      env['DYLIB_INSTALL_NAME_BASE'] = install_name_base
    if XcodeVersion() >= '0500' and not env.get('SDKROOT'):
      sdk_root = xcode_settings._SdkRoot(configuration)
      if not sdk_root:
        sdk_root = xcode_settings._XcodeSdkPath('')
      if sdk_root is None:
        sdk_root = ''
      env['SDKROOT'] = sdk_root
  
    if not additional_settings:
      additional_settings = {}
    else:
      # Flatten lists to strings.
      for k in additional_settings:
        if not isinstance(additional_settings[k], str):
          additional_settings[k] = ' '.join(additional_settings[k])
    additional_settings.update(env)
  
    for k in additional_settings:
      additional_settings[k] = _NormalizeEnvVarReferences(additional_settings[k])
  
    return additional_settings
  
  
  def _NormalizeEnvVarReferences(str):
    """Takes a string containing variable references in the form ${FOO}, $(FOO),
    or $FOO, and returns a string with all variable references in the form ${FOO}.
    """
    # $FOO -> ${FOO}
    str = re.sub(r'\$([a-zA-Z_][a-zA-Z0-9_]*)', r'${\1}', str)
  
    # $(FOO) -> ${FOO}
    matches = re.findall(r'(\$\(([a-zA-Z0-9\-_]+)\))', str)
    for match in matches:
      to_replace, variable = match
      assert '$(' not in match, '$($(FOO)) variables not supported: ' + match
      str = str.replace(to_replace, '${' + variable + '}')
  
    return str
  
  
  def ExpandEnvVars(string, expansions):
    """Expands ${VARIABLES}, $(VARIABLES), and $VARIABLES in string per the
    expansions list. If the variable expands to something that references
    another variable, this variable is expanded as well if it's in env --
    until no variables present in env are left."""
    for k, v in reversed(expansions):
      string = string.replace('${' + k + '}', v)
      string = string.replace('$(' + k + ')', v)
      string = string.replace('$' + k, v)
    return string
  
  
  def _TopologicallySortedEnvVarKeys(env):
    """Takes a dict |env| whose values are strings that can refer to other keys,
    for example env['foo'] = '$(bar) and $(baz)'. Returns a list L of all keys of
    env such that key2 is after key1 in L if env[key2] refers to env[key1].
  
    Throws an Exception in case of dependency cycles.
    """
    # Since environment variables can refer to other variables, the evaluation
    # order is important. Below is the logic to compute the dependency graph
    # and sort it.
    regex = re.compile(r'\$\{([a-zA-Z0-9\-_]+)\}')
    def GetEdges(node):
      # Use a definition of edges such that user_of_variable -> used_varible.
      # This happens to be easier in this case, since a variable's
      # definition contains all variables it references in a single string.
      # We can then reverse the result of the topological sort at the end.
      # Since: reverse(topsort(DAG)) = topsort(reverse_edges(DAG))
      matches = set([v for v in regex.findall(env[node]) if v in env])
      for dependee in matches:
        assert '${' not in dependee, 'Nested variables not supported: ' + dependee
      return matches
  
    try:
      # Topologically sort, and then reverse, because we used an edge definition
      # that's inverted from the expected result of this function (see comment
      # above).
      order = gyp.common.TopologicallySorted(env.keys(), GetEdges)
      order.reverse()
      return order
    except gyp.common.CycleError, e:
      raise GypError(
          'Xcode environment variables are cyclically dependent: ' + str(e.nodes))
  
  
  def GetSortedXcodeEnv(xcode_settings, built_products_dir, srcroot,
                        configuration, additional_settings=None):
    env = _GetXcodeEnv(xcode_settings, built_products_dir, srcroot, configuration,
                      additional_settings)
    return [(key, env[key]) for key in _TopologicallySortedEnvVarKeys(env)]
  
  
  def GetSpecPostbuildCommands(spec, quiet=False):
    """Returns the list of postbuilds explicitly defined on |spec|, in a form
    executable by a shell."""
    postbuilds = []
    for postbuild in spec.get('postbuilds', []):
      if not quiet:
        postbuilds.append('echo POSTBUILD\\(%s\\) %s' % (
              spec['target_name'], postbuild['postbuild_name']))
      postbuilds.append(gyp.common.EncodePOSIXShellList(postbuild['action']))
    return postbuilds
  
  
  def _HasIOSTarget(targets):
    """Returns true if any target contains the iOS specific key
    IPHONEOS_DEPLOYMENT_TARGET."""
    for target_dict in targets.values():
      for config in target_dict['configurations'].values():
        if config.get('xcode_settings', {}).get('IPHONEOS_DEPLOYMENT_TARGET'):
          return True
    return False
  
  
  def _AddIOSDeviceConfigurations(targets):
    """Clone all targets and append -iphoneos to the name. Configure these targets
    to build for iOS devices and use correct architectures for those builds."""
    for target_dict in targets.itervalues():
      toolset = target_dict['toolset']
      configs = target_dict['configurations']
      for config_name, config_dict in dict(configs).iteritems():
        iphoneos_config_dict = copy.deepcopy(config_dict)
        configs[config_name + '-iphoneos'] = iphoneos_config_dict
        configs[config_name + '-iphonesimulator'] = config_dict
        if toolset == 'target':
          iphoneos_config_dict['xcode_settings']['SDKROOT'] = 'iphoneos'
    return targets
  
  def CloneConfigurationForDeviceAndEmulator(target_dicts):
    """If |target_dicts| contains any iOS targets, automatically create -iphoneos
    targets for iOS device builds."""
    if _HasIOSTarget(target_dicts):
      return _AddIOSDeviceConfigurations(target_dicts)
    return target_dicts
  