pw_protobuf_compiler/proto.gni - pigweed/pigweed - Git at Google

 # Copyright 2020 The Pigweed Authors
 #
 # Licensed under the Apache License, Version 2.0 (the "License"); you may not
 # use this file except in compliance with the License. You may obtain a copy of
 # the License at
 #
 #     https://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations under
 # the License.

 import("//build_overrides/pigweed.gni")

 import("$dir_pw_build/error.gni")
 import("$dir_pw_build/input_group.gni")
 import("$dir_pw_build/python.gni")
 import("$dir_pw_build/python_action.gni")
 import("$dir_pw_build/target_types.gni")
 import("$dir_pw_third_party/nanopb/nanopb.gni")

 # Variables forwarded from the public pw_proto_library template to the final
 # pw_source_set.
 _forwarded_vars = [
   "testonly",
   "visibility",
 ]

 # Internal template that invokes protoc with a pw_python_action. This should not
 # be used outside of this file; use pw_proto_library instead.
 #
 # This creates the internal GN target $target_name.$language._gen that compiles
 # proto files with protoc.
 template("_pw_invoke_protoc") {
   _output = rebase_path(get_target_outputs(":${invoker.base_target}._metadata"))

   pw_python_action("$target_name._gen") {
     forward_variables_from(invoker, [ "metadata" ])
     script =
         "$dir_pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py"

     deps = [
              ":${invoker.base_target}._metadata",
              ":${invoker.base_target}._inputs",
            ] + invoker.deps

     args = [
              "--language",
              invoker.language,
              "--module-path",
              rebase_path("."),
              "--include-file",
              _output[0],
              "--out-dir",
              rebase_path(invoker.gen_dir),
            ] + rebase_path(invoker.sources)

     inputs = invoker.sources

     if (defined(invoker.plugin)) {
       inputs += [ invoker.plugin ]
       args += [ "--plugin-path=" + rebase_path(invoker.plugin) ]
     }

     if (defined(invoker.include_paths)) {
       args += [
         "--include-paths",
         string_join(";", rebase_path(invoker.include_paths)),
       ]
     }

     outputs = []
     foreach(extension, invoker.output_extensions) {
       foreach(proto,
               rebase_path(invoker.sources, get_path_info(".", "abspath"))) {
         _output = string_replace(proto, ".proto", extension)
         outputs += [ "${invoker.gen_dir}/$_output" ]
       }
     }

     if (outputs == []) {
       stamp = true
     }

     visibility = [ ":*" ]
   }
 }

 # Generates pw_protobuf C++ code for proto files, creating a source_set of the
 # generated files. This is internal and should not be used outside of this file.
 # Use pw_proto_library instead.
 template("_pw_pwpb_proto_library") {
   _pw_invoke_protoc(target_name) {
     forward_variables_from(invoker, "*", _forwarded_vars)
     language = "pwpb"
     plugin = "$dir_pw_protobuf/py/pw_protobuf/plugin.py"
     deps += [ "$dir_pw_protobuf/py" ]
     output_extensions = [ ".pwpb.h" ]
   }

   # Create a library with the generated source files.
   pw_source_set(target_name) {
     forward_variables_from(invoker, _forwarded_vars)
     public_configs = [ ":${invoker.base_target}._include_path" ]
     deps = [ ":$target_name._gen" ]
     public_deps = [ dir_pw_protobuf ] + invoker.deps
     sources = get_target_outputs(":$target_name._gen")
     public = filter_include(sources, [ "*.pwpb.h" ])
   }
 }

 # Generates nanopb RPC code for proto files, creating a source_set of the
 # generated files. This is internal and should not be used outside of this file.
 # Use pw_proto_library instead.
 template("_pw_nanopb_rpc_proto_library") {
   # Create a target which runs protoc configured with the nanopb_rpc plugin to
   # generate the C++ proto RPC headers.
   _pw_invoke_protoc(target_name) {
     forward_variables_from(invoker, "*", _forwarded_vars)
     language = "nanopb_rpc"
     plugin = "$dir_pw_rpc/py/pw_rpc/plugin_nanopb.py"
     deps += [ "$dir_pw_rpc/py" ]
     include_paths = [ "$dir_pw_third_party_nanopb/generator/proto" ]
     output_extensions = [ ".rpc.pb.h" ]
   }

   # Create a library with the generated source files.
   pw_source_set(target_name) {
     forward_variables_from(invoker, _forwarded_vars)
     public_configs = [ ":${invoker.base_target}._include_path" ]
     deps = [ ":$target_name._gen" ]
     public_deps = [
                     ":${invoker.base_target}.nanopb",
                     "$dir_pw_rpc:server",
                     "$dir_pw_rpc/nanopb:method_union",
                     "$dir_pw_third_party/nanopb",
                   ] + invoker.deps
     public = get_target_outputs(":$target_name._gen")
   }
 }

 # Generates nanopb code for proto files, creating a source_set of the generated
 # files. This is internal and should not be used outside of this file. Use
 # pw_proto_library instead.
 template("_pw_nanopb_proto_library") {
   # Create a target which runs protoc configured with the nanopb plugin to
   # generate the C proto sources.
   _pw_invoke_protoc(target_name) {
     forward_variables_from(invoker, "*", _forwarded_vars)
     language = "nanopb"
     plugin = "$dir_pw_third_party_nanopb/generator/protoc-gen-nanopb"
     include_paths = [ "$dir_pw_third_party_nanopb/generator/proto" ]
     output_extensions = [
       ".pb.h",
       ".pb.c",
     ]
   }

   # Create a library with the generated source files.
   pw_source_set(target_name) {
     forward_variables_from(invoker, _forwarded_vars)
     public_configs = [ ":${invoker.base_target}._include_path" ]
     deps = [ ":$target_name._gen" ]
     public_deps = [ "$dir_pw_third_party/nanopb" ] + invoker.deps
     sources = get_target_outputs(":$target_name._gen")
     public = filter_include(sources, [ "*.pb.h" ])
   }
 }

 # Generates raw RPC code for proto files, creating a source_set of the generated
 # files. This is internal and should not be used outside of this file. Use
 # pw_proto_library instead.
 template("_pw_raw_rpc_proto_library") {
   # Create a target which runs protoc configured with the nanopb_rpc plugin to
   # generate the C++ proto RPC headers.
   _pw_invoke_protoc(target_name) {
     forward_variables_from(invoker, "*", _forwarded_vars)
     language = "raw_rpc"
     plugin = "$dir_pw_rpc/py/pw_rpc/plugin_raw.py"
     deps += [ "$dir_pw_rpc/py" ]
     output_extensions = [ ".raw_rpc.pb.h" ]
   }

   # Create a library with the generated source files.
   pw_source_set(target_name) {
     forward_variables_from(invoker, _forwarded_vars)
     public_configs = [ ":${invoker.base_target}._include_path" ]
     deps = [ ":$target_name._gen" ]
     public_deps = [
                     "$dir_pw_rpc:server",
                     "$dir_pw_rpc/raw:method_union",
                   ] + invoker.deps
     public = get_target_outputs(":$target_name._gen")
   }
 }

 # Generates Go code for proto files, listing the proto output directory in the
 # metadata variable GOPATH. Internal use only.
 template("_pw_go_proto_library") {
   _proto_gopath = "$root_gen_dir/go"

   _pw_invoke_protoc(target_name) {
     forward_variables_from(invoker, "*")
     language = "go"
     metadata = {
       gopath = [ "GOPATH+=" + rebase_path(_proto_gopath) ]
       external_deps = [
         "github.com/golang/protobuf/proto",
         "google.golang.org/grpc",
       ]
     }
     output_extensions = []  # Don't enumerate the generated .go files.
     gen_dir = "$_proto_gopath/src"
   }

   group(target_name) {
     deps = [ ":$target_name._gen" ]
   }
 }

 # Generates Python code for proto files, creating a pw_python_package containing
 # the generated files. This is internal and should not be used outside of this
 # file. Use pw_proto_library instead.
 template("_pw_python_proto_library") {
   _target = target_name
   _package_dir = ""

   foreach(_rebased_proto_path, rebase_path(invoker.sources, ".")) {
     _path_components = []
     _path_components = string_split(_rebased_proto_path, "/")

     assert(_path_components != [ _rebased_proto_path ] &&
                _path_components[0] != "..",
            "Sources in a pw_proto_library must live in subdirectories " +
                "of where it is defined")

     if (_package_dir == "") {
       _package_dir = _path_components[0]
     } else {
       assert(_path_components[0] == _package_dir,
              "All .proto sources in a pw_proto_library must live " +
                  "in the same directory tree")
     }
   }

   _pw_invoke_protoc(target_name) {
     forward_variables_from(invoker, "*", _forwarded_vars)
     language = "python"
     output_extensions = [ "_pb2.py" ]
   }

   _setup_py = "${invoker.gen_dir}/setup.py"

   # Create the setup and init files for the Python package.
   pw_python_action(target_name + "._package_gen") {
     script = "$dir_pw_protobuf_compiler/py/pw_protobuf_compiler/generate_python_package.py"
     args = [
              "--setup",
              rebase_path(_setup_py),
              "--package",
              _package_dir,
            ] + rebase_path(get_path_info(invoker.sources, "dir"), ".")
     public_deps = [ ":$_target._gen" ]
     stamp = true
   }

   # Create a Python package with the generated source files.
   pw_python_package(target_name) {
     forward_variables_from(invoker, _forwarded_vars)
     setup = [ _setup_py ]
     sources = get_target_outputs(":$target_name._gen")
     python_deps = invoker.deps
     other_deps = [ ":$_target._package_gen" ]
     _pw_generated = true
   }
 }

 # Generates protobuf code from .proto definitions for various languages.
 # For each supported generator, creates a sub-target named:
 #
 #   <target_name>.<generator>
 #
 # Args:
 #  sources: List of input .proto files.
 #  deps: List of other pw_proto_library dependencies.
 #  inputs: Other files on which the protos depend (e.g. nanopb .options files).
 #
 template("pw_proto_library") {
   assert(defined(invoker.sources) && invoker.sources != [],
          "pw_proto_library requires .proto source files")

   _common = {
     base_target = target_name
     gen_dir = "$target_gen_dir/protos"
     sources = invoker.sources
   }

   if (defined(invoker.deps)) {
     _deps = invoker.deps
   } else {
     _deps = []
   }

   # For each proto target, create a file which collects the base directories of
   # all of its dependencies to list as include paths to protoc.
   generated_file("$target_name._metadata") {
     # Collect metadata from the include path files of each dependency.
     deps = process_file_template(_deps, "{{source}}._metadata")

     data_keys = [ "protoc_includes" ]
     outputs = [ "$target_gen_dir/${_common.base_target}_includes.txt" ]

     # Indicate this library's base directory for its dependents.
     metadata = {
       protoc_includes = [ rebase_path(".") ]
     }
   }

   # Toss any additional inputs into an input group dependency.
   if (defined(invoker.inputs)) {
     pw_input_group("$target_name._inputs") {
       inputs = invoker.inputs
       visibility = [ ":*" ]
     }
   } else {
     group("$target_name._inputs") {
       visibility = [ ":*" ]
     }
   }

   # Create a config with the generated proto directory, which is used for C++.
   config("$target_name._include_path") {
     include_dirs = [ _common.gen_dir ]
     visibility = [ ":*" ]
   }

   # Enumerate all of the protobuf generator targets.

   _pw_pwpb_proto_library("$target_name.pwpb") {
     forward_variables_from(invoker, _forwarded_vars)
     forward_variables_from(_common, "*")
     deps = process_file_template(_deps, "{{source}}.pwpb")
   }

   if (dir_pw_third_party_nanopb != "") {
     _pw_nanopb_rpc_proto_library("$target_name.nanopb_rpc") {
       forward_variables_from(invoker, _forwarded_vars)
       forward_variables_from(_common, "*")
       deps = process_file_template(_deps, "{{source}}.nanopb_rpc")
     }

     _pw_nanopb_proto_library("$target_name.nanopb") {
       forward_variables_from(invoker, _forwarded_vars)
       forward_variables_from(_common, "*")
       deps = process_file_template(_deps, "{{source}}.nanopb")
     }
   } else {
     pw_error("$target_name.nanopb_rpc") {
       message =
           "\$dir_pw_third_party_nanopb must be set to generate nanopb RPC code."
     }

     pw_error("$target_name.nanopb") {
       message =
           "\$dir_pw_third_party_nanopb must be set to compile nanopb protobufs."
     }
   }

   _pw_raw_rpc_proto_library("$target_name.raw_rpc") {
     forward_variables_from(invoker, _forwarded_vars)
     forward_variables_from(_common, "*", [ "deps" ])
     deps = process_file_template(_deps, "{{source}}.raw_rpc")
   }

   _pw_go_proto_library("$target_name.go") {
     sources = invoker.sources
     deps = process_file_template(_deps, "{{source}}.go")
     base_target = _common.base_target
   }

   _pw_python_proto_library("$target_name.python") {
     sources = invoker.sources
     forward_variables_from(_common, "*")
     deps = process_file_template(_deps, "{{source}}.python")
     base_target = _common.base_target
   }

   # All supported pw_protobuf generators.
   _protobuf_generators = [
     "pwpb",
     "nanopb",
     "nanopb_rpc",
     "raw_rpc",
     "go",
     "python",
   ]

   # If the user attempts to use the target directly instead of one of the
   # generator targets, run a script which prints a nice error message.
   pw_python_action(target_name) {
     script = string_join("/",
                          [
                            dir_pw_protobuf_compiler,
                            "py",
                            "pw_protobuf_compiler",
                            "proto_target_invalid.py",
                          ])
     args = [
              "--target",
              target_name,
              "--dir",
              get_path_info(".", "abspath"),
              "--root",
              "//",
            ] + _protobuf_generators
     stamp = true
   }
 }
	# Copyright 2020 The Pigweed Authors
	#
	# Licensed under the Apache License, Version 2.0 (the "License"); you may not
	# use this file except in compliance with the License. You may obtain a copy of
	# the License at
	#
	# https://www.apache.org/licenses/LICENSE-2.0
	#
	# Unless required by applicable law or agreed to in writing, software
	# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	# License for the specific language governing permissions and limitations under
	# the License.

	import("//build_overrides/pigweed.gni")

	import("$dir_pw_build/error.gni")
	import("$dir_pw_build/input_group.gni")
	import("$dir_pw_build/python.gni")
	import("$dir_pw_build/python_action.gni")
	import("$dir_pw_build/target_types.gni")
	import("$dir_pw_third_party/nanopb/nanopb.gni")

	# Variables forwarded from the public pw_proto_library template to the final
	# pw_source_set.
	_forwarded_vars = [
	"testonly",
	"visibility",
	]

	# Internal template that invokes protoc with a pw_python_action. This should not
	# be used outside of this file; use pw_proto_library instead.
	#
	# This creates the internal GN target $target_name.$language._gen that compiles
	# proto files with protoc.
	template("_pw_invoke_protoc") {
	_output = rebase_path(get_target_outputs(":${invoker.base_target}._metadata"))

	pw_python_action("$target_name._gen") {
	forward_variables_from(invoker, [ "metadata" ])
	script =
	"$dir_pw_protobuf_compiler/py/pw_protobuf_compiler/generate_protos.py"

	deps = [
	":${invoker.base_target}._metadata",
	":${invoker.base_target}._inputs",
	] + invoker.deps

	args = [
	"--language",
	invoker.language,
	"--module-path",
	rebase_path("."),
	"--include-file",
	_output[0],
	"--out-dir",
	rebase_path(invoker.gen_dir),
	] + rebase_path(invoker.sources)

	inputs = invoker.sources

	if (defined(invoker.plugin)) {
	inputs += [ invoker.plugin ]
	args += [ "--plugin-path=" + rebase_path(invoker.plugin) ]
	}

	if (defined(invoker.include_paths)) {
	args += [
	"--include-paths",
	string_join(";", rebase_path(invoker.include_paths)),
	]
	}

	outputs = []
	foreach(extension, invoker.output_extensions) {
	foreach(proto,
	rebase_path(invoker.sources, get_path_info(".", "abspath"))) {
	_output = string_replace(proto, ".proto", extension)
	outputs += [ "${invoker.gen_dir}/$_output" ]
	}
	}

	if (outputs == []) {
	stamp = true
	}

	visibility = [ ":*" ]
	}
	}

	# Generates pw_protobuf C++ code for proto files, creating a source_set of the
	# generated files. This is internal and should not be used outside of this file.
	# Use pw_proto_library instead.
	template("_pw_pwpb_proto_library") {
	_pw_invoke_protoc(target_name) {
	forward_variables_from(invoker, "*", _forwarded_vars)
	language = "pwpb"
	plugin = "$dir_pw_protobuf/py/pw_protobuf/plugin.py"
	deps += [ "$dir_pw_protobuf/py" ]
	output_extensions = [ ".pwpb.h" ]
	}

	# Create a library with the generated source files.
	pw_source_set(target_name) {
	forward_variables_from(invoker, _forwarded_vars)
	public_configs = [ ":${invoker.base_target}._include_path" ]
	deps = [ ":$target_name._gen" ]
	public_deps = [ dir_pw_protobuf ] + invoker.deps
	sources = get_target_outputs(":$target_name._gen")
	public = filter_include(sources, [ "*.pwpb.h" ])
	}
	}

	# Generates nanopb RPC code for proto files, creating a source_set of the
	# generated files. This is internal and should not be used outside of this file.
	# Use pw_proto_library instead.
	template("_pw_nanopb_rpc_proto_library") {
	# Create a target which runs protoc configured with the nanopb_rpc plugin to
	# generate the C++ proto RPC headers.
	_pw_invoke_protoc(target_name) {
	forward_variables_from(invoker, "*", _forwarded_vars)
	language = "nanopb_rpc"
	plugin = "$dir_pw_rpc/py/pw_rpc/plugin_nanopb.py"
	deps += [ "$dir_pw_rpc/py" ]
	include_paths = [ "$dir_pw_third_party_nanopb/generator/proto" ]
	output_extensions = [ ".rpc.pb.h" ]
	}

	# Create a library with the generated source files.
	pw_source_set(target_name) {
	forward_variables_from(invoker, _forwarded_vars)
	public_configs = [ ":${invoker.base_target}._include_path" ]
	deps = [ ":$target_name._gen" ]
	public_deps = [
	":${invoker.base_target}.nanopb",
	"$dir_pw_rpc:server",
	"$dir_pw_rpc/nanopb:method_union",
	"$dir_pw_third_party/nanopb",
	] + invoker.deps
	public = get_target_outputs(":$target_name._gen")
	}
	}

	# Generates nanopb code for proto files, creating a source_set of the generated
	# files. This is internal and should not be used outside of this file. Use
	# pw_proto_library instead.
	template("_pw_nanopb_proto_library") {
	# Create a target which runs protoc configured with the nanopb plugin to
	# generate the C proto sources.
	_pw_invoke_protoc(target_name) {
	forward_variables_from(invoker, "*", _forwarded_vars)
	language = "nanopb"
	plugin = "$dir_pw_third_party_nanopb/generator/protoc-gen-nanopb"
	include_paths = [ "$dir_pw_third_party_nanopb/generator/proto" ]
	output_extensions = [
	".pb.h",
	".pb.c",
	]
	}

	# Create a library with the generated source files.
	pw_source_set(target_name) {
	forward_variables_from(invoker, _forwarded_vars)
	public_configs = [ ":${invoker.base_target}._include_path" ]
	deps = [ ":$target_name._gen" ]
	public_deps = [ "$dir_pw_third_party/nanopb" ] + invoker.deps
	sources = get_target_outputs(":$target_name._gen")
	public = filter_include(sources, [ "*.pb.h" ])
	}
	}

	# Generates raw RPC code for proto files, creating a source_set of the generated
	# files. This is internal and should not be used outside of this file. Use
	# pw_proto_library instead.
	template("_pw_raw_rpc_proto_library") {
	# Create a target which runs protoc configured with the nanopb_rpc plugin to
	# generate the C++ proto RPC headers.
	_pw_invoke_protoc(target_name) {
	forward_variables_from(invoker, "*", _forwarded_vars)
	language = "raw_rpc"
	plugin = "$dir_pw_rpc/py/pw_rpc/plugin_raw.py"
	deps += [ "$dir_pw_rpc/py" ]
	output_extensions = [ ".raw_rpc.pb.h" ]
	}

	# Create a library with the generated source files.
	pw_source_set(target_name) {
	forward_variables_from(invoker, _forwarded_vars)
	public_configs = [ ":${invoker.base_target}._include_path" ]
	deps = [ ":$target_name._gen" ]
	public_deps = [
	"$dir_pw_rpc:server",
	"$dir_pw_rpc/raw:method_union",
	] + invoker.deps
	public = get_target_outputs(":$target_name._gen")
	}
	}

	# Generates Go code for proto files, listing the proto output directory in the
	# metadata variable GOPATH. Internal use only.
	template("_pw_go_proto_library") {
	_proto_gopath = "$root_gen_dir/go"

	_pw_invoke_protoc(target_name) {
	forward_variables_from(invoker, "*")
	language = "go"
	metadata = {
	gopath = [ "GOPATH+=" + rebase_path(_proto_gopath) ]
	external_deps = [
	"github.com/golang/protobuf/proto",
	"google.golang.org/grpc",
	]
	}
	output_extensions = [] # Don't enumerate the generated .go files.
	gen_dir = "$_proto_gopath/src"
	}

	group(target_name) {
	deps = [ ":$target_name._gen" ]
	}
	}

	# Generates Python code for proto files, creating a pw_python_package containing
	# the generated files. This is internal and should not be used outside of this
	# file. Use pw_proto_library instead.
	template("_pw_python_proto_library") {
	_target = target_name
	_package_dir = ""

	foreach(_rebased_proto_path, rebase_path(invoker.sources, ".")) {
	_path_components = []
	_path_components = string_split(_rebased_proto_path, "/")

	assert(_path_components != [ _rebased_proto_path ] &&
	_path_components[0] != "..",
	"Sources in a pw_proto_library must live in subdirectories " +
	"of where it is defined")

	if (_package_dir == "") {
	_package_dir = _path_components[0]
	} else {
	assert(_path_components[0] == _package_dir,
	"All .proto sources in a pw_proto_library must live " +
	"in the same directory tree")
	}
	}

	_pw_invoke_protoc(target_name) {
	forward_variables_from(invoker, "*", _forwarded_vars)
	language = "python"
	output_extensions = [ "_pb2.py" ]
	}

	_setup_py = "${invoker.gen_dir}/setup.py"

	# Create the setup and init files for the Python package.
	pw_python_action(target_name + "._package_gen") {
	script = "$dir_pw_protobuf_compiler/py/pw_protobuf_compiler/generate_python_package.py"
	args = [
	"--setup",
	rebase_path(_setup_py),
	"--package",
	_package_dir,
	] + rebase_path(get_path_info(invoker.sources, "dir"), ".")
	public_deps = [ ":$_target._gen" ]
	stamp = true
	}

	# Create a Python package with the generated source files.
	pw_python_package(target_name) {
	forward_variables_from(invoker, _forwarded_vars)
	setup = [ _setup_py ]
	sources = get_target_outputs(":$target_name._gen")
	python_deps = invoker.deps
	other_deps = [ ":$_target._package_gen" ]
	_pw_generated = true
	}
	}

	# Generates protobuf code from .proto definitions for various languages.
	# For each supported generator, creates a sub-target named:
	#
	# <target_name>.<generator>
	#
	# Args:
	# sources: List of input .proto files.
	# deps: List of other pw_proto_library dependencies.
	# inputs: Other files on which the protos depend (e.g. nanopb .options files).
	#
	template("pw_proto_library") {
	assert(defined(invoker.sources) && invoker.sources != [],
	"pw_proto_library requires .proto source files")

	_common = {
	base_target = target_name
	gen_dir = "$target_gen_dir/protos"
	sources = invoker.sources
	}

	if (defined(invoker.deps)) {
	_deps = invoker.deps
	} else {
	_deps = []
	}

	# For each proto target, create a file which collects the base directories of
	# all of its dependencies to list as include paths to protoc.
	generated_file("$target_name._metadata") {
	# Collect metadata from the include path files of each dependency.
	deps = process_file_template(_deps, "{{source}}._metadata")

	data_keys = [ "protoc_includes" ]
	outputs = [ "$target_gen_dir/${_common.base_target}_includes.txt" ]

	# Indicate this library's base directory for its dependents.
	metadata = {
	protoc_includes = [ rebase_path(".") ]
	}
	}

	# Toss any additional inputs into an input group dependency.
	if (defined(invoker.inputs)) {
	pw_input_group("$target_name._inputs") {
	inputs = invoker.inputs
	visibility = [ ":*" ]
	}
	} else {
	group("$target_name._inputs") {
	visibility = [ ":*" ]
	}
	}

	# Create a config with the generated proto directory, which is used for C++.
	config("$target_name._include_path") {
	include_dirs = [ _common.gen_dir ]
	visibility = [ ":*" ]
	}

	# Enumerate all of the protobuf generator targets.

	_pw_pwpb_proto_library("$target_name.pwpb") {
	forward_variables_from(invoker, _forwarded_vars)
	forward_variables_from(_common, "*")
	deps = process_file_template(_deps, "{{source}}.pwpb")
	}

	if (dir_pw_third_party_nanopb != "") {
	_pw_nanopb_rpc_proto_library("$target_name.nanopb_rpc") {
	forward_variables_from(invoker, _forwarded_vars)
	forward_variables_from(_common, "*")
	deps = process_file_template(_deps, "{{source}}.nanopb_rpc")
	}

	_pw_nanopb_proto_library("$target_name.nanopb") {
	forward_variables_from(invoker, _forwarded_vars)
	forward_variables_from(_common, "*")
	deps = process_file_template(_deps, "{{source}}.nanopb")
	}
	} else {
	pw_error("$target_name.nanopb_rpc") {
	message =
	"\$dir_pw_third_party_nanopb must be set to generate nanopb RPC code."
	}

	pw_error("$target_name.nanopb") {
	message =
	"\$dir_pw_third_party_nanopb must be set to compile nanopb protobufs."
	}
	}

	_pw_raw_rpc_proto_library("$target_name.raw_rpc") {
	forward_variables_from(invoker, _forwarded_vars)
	forward_variables_from(_common, "*", [ "deps" ])
	deps = process_file_template(_deps, "{{source}}.raw_rpc")
	}

	_pw_go_proto_library("$target_name.go") {
	sources = invoker.sources
	deps = process_file_template(_deps, "{{source}}.go")
	base_target = _common.base_target
	}

	_pw_python_proto_library("$target_name.python") {
	sources = invoker.sources
	forward_variables_from(_common, "*")
	deps = process_file_template(_deps, "{{source}}.python")
	base_target = _common.base_target
	}

	# All supported pw_protobuf generators.
	_protobuf_generators = [
	"pwpb",
	"nanopb",
	"nanopb_rpc",
	"raw_rpc",
	"go",
	"python",
	]

	# If the user attempts to use the target directly instead of one of the
	# generator targets, run a script which prints a nice error message.
	pw_python_action(target_name) {
	script = string_join("/",
	[
	dir_pw_protobuf_compiler,
	"py",
	"pw_protobuf_compiler",
	"proto_target_invalid.py",
	])
	args = [
	"--target",
	target_name,
	"--dir",
	get_path_info(".", "abspath"),
	"--root",
	"//",
	] + _protobuf_generators
	stamp = true
	}
	}