scripts/build_helpers/generate_build_files.py

#!/usr/bin/env python3
# Copyright 2025 Google LLC
#
# 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.

"""Generates build helper files from `build.json`."""

import json
import os

COPYRIGHT_HEADER = """# Copyright 2025 Google LLC
#
# 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.
"""


def read_build_json(file_path):
    """Reads build.json, strips comments, and returns the parsed JSON data."""
    with open(file_path, "r") as f:
        # Simple comment stripping for JSONC format
        content = "".join(line for line in f if not line.strip().startswith("//"))
    return json.loads(content)


def generate_sources_json(output_dir, data):
    """Generates gen/sources.json."""
    output_path = os.path.join(output_dir, "sources.json")
    with open(output_path, "w") as f:
        json.dump(data, f, indent=4)
        f.write("\n")
    print(f"Generated {output_path}")


def generate_sources_bzl(output_dir, data):
    """Generates gen/sources.bzl."""
    output_path = os.path.join(output_dir, "sources.bzl")
    with open(output_path, "w") as f:
        f.write(COPYRIGHT_HEADER)
        f.write("\n\n")
        f.write("# Automatically generated by generate_build_files.py.\n")
        f.write("# Do not edit this file directly.\n")
        f.write("\n")
        f.write("EMBOSSC_SOURCES = [\n")
        for source in data["embossc_sources"]:
            f.write(f'    "{source}",\n')
        f.write("]\n\n")
        f.write("EMBOSS_RUNTIME_CPP_SOURCES = [\n")
        for source in data["emboss_runtime_cpp_sources"]:
            f.write(f'    "{source}",\n')
        f.write("]\n")
    print(f"Generated {output_path}")


def generate_sources_cmake(output_dir, data):
    """Generates gen/sources.cmake."""
    output_path = os.path.join(output_dir, "sources.cmake")
    with open(output_path, "w") as f:
        f.write(COPYRIGHT_HEADER)
        f.write("\n\n")
        f.write("# Automatically generated by generate_build_files.py.\n")
        f.write("# Do not edit this file directly.\n\n")
        f.write("set(EMBOSSC_SOURCES\n")
        for source in data["embossc_sources"]:
            f.write(f'  "{source}"\n')
        f.write(")\n\n")
        f.write("set(EMBOSS_RUNTIME_CPP_SOURCES\n")
        for source in data["emboss_runtime_cpp_sources"]:
            f.write(f'  "{source}"\n')
        f.write(")\n")
    print(f"Generated {output_path}")


def generate_sources_gni(output_dir, data):
    """Generates gen/sources.gni."""
    output_path = os.path.join(output_dir, "sources.gni")
    with open(output_path, "w") as f:
        f.write(COPYRIGHT_HEADER)
        f.write("\n\n")
        f.write("# Automatically generated by generate_build_files.py.\n")
        f.write("# Do not edit this file directly.\n\n")
        f.write("embossc_sources = [\n")
        for source in data["embossc_sources"]:
            f.write(f'  "{source}",\n')
        f.write("]\n\n")
        f.write("emboss_runtime_cpp_sources = [\n")
        for source in data["emboss_runtime_cpp_sources"]:
            f.write(f'  "{source}",\n')
        f.write("]\n")
    print(f"Generated {output_path}")


def main():
    workspace_root = os.environ.get("BUILD_WORKSPACE_DIRECTORY", os.getcwd())
    build_json_path = os.path.join(workspace_root, "build.json")
    gen_dir = os.path.join(workspace_root, "gen")

    os.makedirs(gen_dir, exist_ok=True)

    data = read_build_json(build_json_path)

    generate_sources_json(gen_dir, data)
    generate_sources_bzl(gen_dir, data)
    generate_sources_cmake(gen_dir, data)
    generate_sources_gni(gen_dir, data)


if __name__ == "__main__":
    main()