Ensure classes only referenced by .xib files end up in the executable

Review URL: http://codereview.chromium.org/27277

git-svn-id: http://src.chromium.org/svn/trunk/src/build@10619 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

mac/make_ib_classes.py

@@ -0,0 +1,146 @@
+#!/usr/bin/python
+
+# Copyright (c) 2009 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.
+
+# Usage: make_ib_classes.py output.mm input.xib [...]
+#
+# Generates an Objective-C++ file at output.mm referencing each class described
+# in input.xib.
+#
+# This script is useful when building an application containing .nib or .xib
+# files that reference Objective-C classes that may not be referenced by other
+# code in the application.  The intended use case is when the .nib and .xib
+# files refer to classes that are built into a static library that gets linked
+# into the main executable.  If nothing in the main executable references those
+# classes, the linker will not include them in its output (without -all_load or
+# -ObjC).  Using this script, references to such classes are created, such that
+# if output.mm is compiled into the application itself, it will provide the
+# class references and cause the linker to bring the required code into the
+# executable.
+#
+# If your application is structured in the above way, and you're plagued with
+# messages like:
+#   app[12345:101] Unknown class `MyApp' in nib file, using `NSObject' instead.
+# then this script may be right for you.
+
+
+import errno
+import os
+import os.path
+import re
+import subprocess
+import sys
+
+
+# Patterns used by ListIBClasses
+
+# A pattern that matches the line preceding a class name.
+_class_re = re.compile('<key>class</key>$')
+
+# A pattern that matches the line with a class name; match group 1 should be
+# the class name.
+_class_name_re = re.compile('<string>(.*)</string>$')
+
+# A pattern that matches class names to exclude from the output.  This includes
+# various Cocoa classes.
+_forbidden_class_re = re.compile('^(NS|IB|FirstResponder$|WebView$)')
+
+def ListIBClasses(ib_path, class_names=None):
+  """Returns a list of class names referenced by ib_path.
+
+  ib_path is a path to an Interface Builder document.  It may be a .nib or a
+  .xib.
+
+  This function calls "ibtool --classes" to get the list of class names.
+  ibtool's output is in XML plist format.  Rather than doing proper structured
+  plist scanning, this function relies on the fact that plists are serialized
+  to XML in a consistent way, and simply takes the string value names of any
+  dictionary key named "class" as class names.
+
+  class_names may be specified as an existing list to use.  This is helpful
+  when this function will be called several times for multiple nib/xib files.
+  """
+  if class_names == None:
+    class_names = []
+
+  # When running within an Xcode build, use the tools from that Xcode
+  # installation.
+  developer_tools_dir = os.getenv('DEVELOPER_BIN_DIR', '/usr/bin')
+  ibtool_path = os.path.join(developer_tools_dir, 'ibtool')
+  ibtool_command = [ibtool_path, '--classes', ib_path]
+
+  ibtool = subprocess.Popen(ibtool_command, stdout=subprocess.PIPE)
+
+  ibtool_output = ibtool.communicate()[0]
+
+  ibtool_rv = ibtool.returncode
+  assert ibtool_rv == 0
+
+  # Loop through the output, looking for "class" keys.  The string value on
+  # any line following a "class" key is taken as a class name.
+  is_class_name = False
+  for line in ibtool_output.splitlines():
+    if is_class_name:
+      class_name = _class_name_re.search(line).group(1)
+      is_class_name = False
+      if not class_name in class_names and \
+         not _forbidden_class_re.search(class_name):
+        class_names.append(class_name)
+    elif _class_re.search(line):
+      is_class_name = True
+
+  return class_names
+
+
+def main(args):
+  assert len(args) > 2
+  (script_path, output_path) = args[0:2]
+  assert output_path.endswith('.mm')
+  input_paths = args[2:]
+
+  try:
+    os.unlink(output_path)
+  except OSError, e:
+    if e.errno != errno.ENOENT:
+      raise
+
+  class_names = []
+
+  # Get the class names for all desired files.
+  for input_path in input_paths:
+    ListIBClasses(input_path, class_names)
+
+  class_names.sort()
+
+  # Write the requested output file.  Each class is referenced simply by
+  # calling its +class function.  In order to do this, each class needs a
+  # bogus @interface to tell the compiler that it's an NSObject subclass.
+  # #import NSObject.h to get the definition of NSObject without bringing in
+  # other headers that might provide real declarations.
+
+  output_file = open(output_path, 'w')
+  print >>output_file, \
+"""// This file was generated by %s.  Do not edit.
+
+#import <Foundation/NSObject.h>
+""" % os.path.basename(script_path)
+
+  for class_name in class_names:
+    print >>output_file, '@interface %s : NSObject\n@end' % class_name
+
+  print >>output_file, '\nnamespace {\n\nvoid IBClasses() {'
+
+  for class_name in class_names:
+    print >>output_file, '  [%s class];' % class_name
+
+  print >>output_file, '}\n\n}  // namespace'
+
+  output_file.close()
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))