build/chip/chip_codegen.gni

# Copyright (c) 2022 Project CHIP 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
#
# http://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/build.gni")
import("//build_overrides/chip.gni")
import("//build_overrides/pigweed.gni")

import("$dir_pw_build/python.gni")
import("${chip_root}/scripts/idl/files.gni")

declare_args() {
  # Location where code has been pre-generated
  chip_code_pre_generated_directory = ""
}

# Code generation that will happen at build time.
#
#
template("_chip_build_time_codegen") {
  _name = target_name
  _generator = invoker.generator

  config("${_name}_config") {
    include_dirs = [ target_gen_dir ]
  }

  pw_python_action("${_name}_codegen") {
    script = "${chip_root}/scripts/codegen.py"

    # TODO: this seems to touch internals. Is this ok? speeds up builds!
    _pw_internal_run_in_venv = false

    _idl_file = invoker.input
    _expected_outputs = "${target_gen_dir}/${_name}.expected.outputs"

    write_file(_expected_outputs, invoker.outputs, "list lines")

    args = [
      "--generator",
      _generator,
      "--output-dir",
      rebase_path(target_gen_dir, root_build_dir),
      "--expected-outputs",
      rebase_path(_expected_outputs, root_build_dir),
      rebase_path(_idl_file, root_build_dir),
    ]

    inputs = [
      _idl_file,
      _expected_outputs,
    ]

    # ensure any change in codegen files will result in a rebuild
    inputs += matter_idl_generator_files

    sources = [ _idl_file ]

    outputs = []
    foreach(name, invoker.outputs) {
      outputs += [ "${target_gen_dir}/${name}" ]
    }
  }

  source_set(_name) {
    sources = []
    foreach(name, invoker.outputs) {
      sources += [ "${target_gen_dir}/${name}" ]
    }

    public_configs = [ ":${_name}_config" ]

    if (defined(invoker.public_configs)) {
      public_configs += invoker.public_configs
    }

    forward_variables_from(invoker, [ "deps" ])

    if (!defined(deps)) {
      deps = []
    }
    deps += [ ":${_name}_codegen" ]
  }
}

# Defines a target that runs code generation based on
# scripts/codegen.py
#
# Arguments:
#   input
#     The ".matter" file to use to start the code generation
#
#   generator
#     Name of the generator to use (e.g. java, cpp-app)
#
#   outputs
#     Explicit names of the expected outputs. Enforced to validate that
#     expected outputs are generated when processing input files.
#
#   deps, public_configs
#     Forwarded to the resulting source set
#
# Command line parameters:
#
#  chip_code_pre_generated_directory:
#     - If this is set, generation will NOT happen at compile time but rather
#       the code generation is assumed to have already happened and reside in
#       the given location.
#     - The TOP LEVEL directory is assumed to be given. Actual location for
#       individual generators is expected to be of the form
#       <top_dir>/<matter_path>/<generator>
#
# NOTE: content of "outputs" is verified to match the output of codegen.py
#       exactly. It is not inferred on purpose, to make build-rules explicit
#       and verifiable (even though codegen.py can at runtime report its outputs)
#
#       To find the list of generated files, you can run codegen.py with the
#       "--name-only" argument
#
# NOTE:
#   the result of the target_name WILL BE a `source_set`. Treat it as such.
#
# Example usage:
#
#  chip_codegen("java-jni-generate") {
#    input = "controller-clusters.matter"
#    generator = "java"
#
#    outputs = [
#       "jni/IdentifyClient-ReadImpl.cpp",
#       "jni/IdentifyClient-InvokeSubscribeImpl.cpp",
#       # ... more to follow
#    ]
#  }
#
template("chip_codegen") {
  if (chip_code_pre_generated_directory == "") {
    _chip_build_time_codegen(target_name) {
      forward_variables_from(invoker,
                             [
                               "deps",
                               "generator",
                               "input",
                               "outputs",
                               "public_configs",
                             ])
    }
  } else {
    _name = target_name

    # This contstructs a path like:
    #  FROM all-clusters-app.matter (inside examples/all-clusters-app/all-clusters-common/)
    #  USING "cpp-app" for generator:
    #    => ${pregen_dir}/examples/all-clusters-app/all-clusters-common/all-clusters-app/codegen/cpp-app
    _generation_dir =
        chip_code_pre_generated_directory + "/" +
        string_replace(rebase_path(invoker.input, chip_root), ".matter", "") +
        "/codegen/" + invoker.generator

    config("${_name}_config") {
      include_dirs = [ "${_generation_dir}" ]
    }

    source_set(_name) {
      public_configs = [ ":${_name}_config" ]

      if (defined(invoker.public_configs)) {
        public_configs += invoker.public_configs
      }

      forward_variables_from(invoker, [ "deps" ])

      sources = []
      foreach(name, invoker.outputs) {
        sources += [ "${_generation_dir}/${name}" ]
      }
    }
  }
}