Unify gyp rules for running protoc.

build/protoc.gypi

+# Copyright (c) 2011 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.
+
+# This file is meant to be included into an target to provide a rule
+# to invoke protoc in a consistent manner.
+#
+# To use this, create a gyp target with the following form:
+# {
+#   'target_name': 'my_proto_lib',
+#   'sources': [
+#     'foo.proto',
+#     'bar.proto',
+#   ],
+#   'variables': {
+#     'proto_dir': 'dir/for/my_proto_lib'
+#   },
+#   'includes': ['path/to/this/gypi/file'],
+# }
+# If necessary, you may add normal .cc files to the sources list or other gyp
+# dependencies.  The proto headers are guaranteed to be generated before any
+# source files, even within this target, are compiled.
+#
+# Targets that gyp-depend on my_proto_lib will be able to include the resulting
+# proto headers with an include like:
+#   #include "dir/for/my_proto_lib/foo.pb.h"
+#
+# Implementation notes:
+# A proto_dir of foo/bar produces
+#   <(SHARED_INTERMEDIATE_DIR)/protoc_out/foo/bar/{file1,file2}.pb.{cc,h}
+#   <(SHARED_INTERMEDIATE_DIR)/pyproto/foo/bar/{file1,file2}_pb2.py
+
+{
+  'type': 'static_library',

[TVL, 2011/08/18 20:22:40]

should this be a default (type?) so the target can be what ever is needed?

[Evan Martin, 2011/08/18 20:24:49]

I considered it, but I figure I can generalize this once I find a user that
requires it.  I see lots of 'type:none' bits in the tree, but they are all only
used in cases where someone didn't understand gyp.

[TVL, 2011/08/18 20:30:13]

Ok, approach makes sense to me.  Mark -

Maybe go ahead and extend this to more places to confirm there aren't other
hiccups?

ps-from a build pov, it would be better to directly use this in the targets that
want to us the protocol buffers rather then have it be another xcode/vsstudio
target that has to exist.

[Mark Mentovai, 2011/08/18 20:32:27]

This shouldn’t set type at all!

[Evan Martin, 2011/08/18 20:51:49]

Done.

+  'variables': {
+    'protoc': '<(PRODUCT_DIR)/<(EXECUTABLE_PREFIX)protoc<(EXECUTABLE_SUFFIX)',
+    'cc_dir': '<(SHARED_INTERMEDIATE_DIR)/protoc_out/<(proto_dir)',
+    'py_dir': '<(PRODUCT_DIR)/pyproto/<(proto_dir)',
+  },
+  'rules': [
+    {
+      'rule_name': 'genproto',
+      'extension': 'proto',
+      'inputs': [
+        '<(protoc)',
+      ],
+      'outputs': [
+        '<(py_dir)/<(RULE_INPUT_ROOT)_pb2.py',
+        '<(cc_dir)/<(RULE_INPUT_ROOT).pb.cc',
+        '<(cc_dir)/<(RULE_INPUT_ROOT).pb.h',
+      ],
+      'action': [
+        '<(protoc)',
+        '--proto_path=.',
+        './<(RULE_INPUT_ROOT)<(RULE_INPUT_EXT)',
+        '--cpp_out=<(cc_dir)',
+        '--python_out=<(py_dir)',
+        ],
+      'message': 'Generating C++ and Python code from <(RULE_INPUT_PATH)',
+      'process_outputs_as_sources': 1,
+    },
+  ],
+  'dependencies': [
+    '<(DEPTH)/third_party/protobuf/protobuf.gyp:protoc#host',
+    '<(DEPTH)/third_party/protobuf/protobuf.gyp:protobuf_lite',
+  ],
+  'include_dirs': [
+    '<(SHARED_INTERMEDIATE_DIR)/protoc_out',
+  ],
+  'direct_dependent_settings': {
+    'include_dirs': [
+      '<(SHARED_INTERMEDIATE_DIR)/protoc_out',
+    ]
+  },
+  # This target exports a hard dependency because it generates header
+  # files.
+  'hard_dependency': 1,
+}