ozone: Implement PlatformObject<T> for platform-specific objects

ui/ozone/generate_ozone_platform_list.py

Index: ui/ozone/generate_ozone_platform_list.py
diff --git a/ui/ozone/generate_ozone_platform_list.py b/ui/ozone/generate_ozone_platform_list.py
index df85a1eab92c136eb5d714d5968c14f53d5c1284..d47c398259b97243d700df86ad4ddd88bf998387 100755
--- a/ui/ozone/generate_ozone_platform_list.py
+++ b/ui/ozone/generate_ozone_platform_list.py
@@ -6,26 +6,47 @@
 """Code generator for Ozone platform list.
 
 This script takes as arguments a list of platform names and generates a C++
-source file containing a list of those platforms. Each list entry contains the
-name and a function pointer to the initializer for that platform.
+source file containing a list of those platforms.
+
+Each platform gets an integer identifier that is used to find objects for that
+platform (particularly constructors for platform-specific objects).
 
 Example Output: ./generate_ozone_platform_list.py --default wayland dri wayland
 
-  #include "ui/ozone/ozone_platform_list.h"
+  // platform_list.txt
+
+  wayland
+  dri
+
+  // platform_list.h
+
+  #ifndef UI_OZONE_PLATFORM_LIST_H_
+  #define UI_OZONE_PLATFORM_LIST_H_
 
   namespace ui {
 
-  OzonePlatform* CreateOzonePlatformDri();
-  OzonePlatform* CreateOzonePlatformWayland();
+  const int kPlatformWayland = 0;
+  const int kPlatformDri = 1;
 
-  const OzonePlatformListEntry kOzonePlatforms[] = {
-    { "wayland", &CreateOzonePlatformWayland },
-    { "dri", &CreateOzonePlatformDri },
-  };
+  extern const char *kPlatformNames[kPlatformCount];
+
+  }  // namespace ui
 
-  const int kOzonePlatformCount = 2;
+  // platform_list.cc
+
+  #include "ui/ozone/platform_list.h"
+
+  namespace ui {
+
+  const char *kPlatformNames[] = {
+   "wayland", // kPlatformWayland
+   "dri", // kPlatformDri
+  };
 
   }  // namespace ui
+
+  #endif  // UI_OZONE_PLATFORM_LIST_H_
+
 """
 
 import optparse
@@ -36,63 +57,118 @@ import sys
 import string
 
 
-def GetConstructorName(name):
+def GetConstantName(name):
   """Determine name of static constructor function from platform name.
 
   We just capitalize the platform name and prepend "CreateOzonePlatform".
   """
 
-  return 'CreateOzonePlatform' + string.capitalize(name)
+  return 'kPlatform' + string.capitalize(name)
 
 
-def GeneratePlatformList(out, platforms):
-  """Generate static array containing a list of ozone platforms."""
+def GeneratePlatformListText(out, platforms):
+  """Generate text file with list of platform names, in platform id order."""
+
+  for platform in platforms:
+    out.write(platform)
+    out.write('\n')
+
+  out.write('\n')
 
-  out.write('#include "ui/ozone/ozone_platform_list.h"\n')
+
+def GeneratePlatformListHeader(out, platforms):
+  """Generate ids of ozone platforms & declaration of static names array."""
+
+  out.write('// DO NOT MODIFY. GENERATED BY generate_ozone_platform_list.py\n')
+  out.write('\n')
+
+  out.write('#ifndef UI_OZONE_PLATFORM_LIST_H_\n')
+  out.write('#define UI_OZONE_PLATFORM_LIST_H_\n')
   out.write('\n')
 
   out.write('namespace ui {\n')
   out.write('\n')
 
   # Prototypes for platform initializers.
-  for platform in platforms:
-    out.write('OzonePlatform* %s();\n' % GetConstructorName(platform))
+  for plat_id, plat_name in enumerate(platforms):
+    out.write('const int %s = %d;\n' % (GetConstantName(plat_name), plat_id))
   out.write('\n')
 
-  # List of platform names and initializers.
-  out.write('const OzonePlatformListEntry kOzonePlatforms[] = {\n')
-  for platform in platforms:
-    out.write('  { "%s", &%s },\n' % (platform, GetConstructorName(platform)))
-  out.write('};\n')
+  # Platform count.
+  out.write('const int kPlatformCount = %d;\n' % len(platforms))
+  out.write('\n')
+
+  # Declaration for names list.
+  out.write('extern const char* kPlatformNames[kPlatformCount];\n')
+  out.write('\n')
+
+  out.write('}  // namespace ui\n')
+  out.write('\n')
+
+  out.write('#endif  // UI_OZONE_PLATFORM_LIST_H_\n')
+  out.write('\n')
+
+
+def GeneratePlatformListSource(out, platforms):
+  """Generate static array containing a list of ozone platforms."""
+
+  out.write('// DO NOT MODIFY. GENERATED BY generate_ozone_platform_list.py\n')
+  out.write('\n')
+
+  out.write('#include "ui/ozone/platform_list.h"\n')
+  out.write('\n')
+
+  out.write('namespace ui {\n')
   out.write('\n')
 
-  out.write('const int kOzonePlatformCount = %d;\n' % len(platforms))
+  # Definition of names list.
+  out.write('const char* kPlatformNames[] = {\n')
+
+  # Prototypes for platform initializers.
+  for plat_name in platforms:
+    out.write('    "%s",  // %s\n' % (plat_name, GetConstantName(plat_name)))
+  out.write('};\n')
   out.write('\n')
 
   out.write('}  // namespace ui\n')
+  out.write('\n')
 
 
 def main(argv):
   parser = optparse.OptionParser()
-  parser.add_option('--output_file')
+  parser.add_option('--output_cc')
+  parser.add_option('--output_h')
+  parser.add_option('--output_txt')
   parser.add_option('--default')
   options, platforms = parser.parse_args(argv)
 
-  # Write to standard output or file specified by --output_file.
-  out = sys.stdout
-  if options.output_file:
-    out = open(options.output_file, 'wb')
-
   # Reorder the platforms when --default is specified.
   # The default platform must appear first in the platform list.
   if options.default and options.default in platforms:
     platforms.remove(options.default)
     platforms.insert(0, options.default)
 
-  GeneratePlatformList(out, platforms)
-
-  if options.output_file:
-    out.close()
+  # Write to standard output or file specified by --output_{cc,h}.
+  out_cc = sys.stdout
+  out_h = sys.stdout
+  out_txt = sys.stdout
+  if options.output_cc:
+    out_cc = open(options.output_cc, 'wb')
+  if options.output_h:
+    out_h = open(options.output_h, 'wb')
+  if options.output_txt:
+    out_txt = open(options.output_txt, 'wb')
+
+  GeneratePlatformListText(out_txt, platforms)
+  GeneratePlatformListHeader(out_h, platforms)
+  GeneratePlatformListSource(out_cc, platforms)
+
+  if options.output_cc:
+    out_cc.close()
+  if options.output_h:
+    out_h.close()
+  if options.output_txt:
+    out_txt.close()
 
   return 0