projects/populate-workspace.py

#!/usr/bin/env python3
# Copyright 2022 The ChromiumOS Authors.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Populates the top-level Cargo.toml with all necessary workspace entries."""

import logging
import os
from pathlib import Path
import sys
from typing import List

WORKSPACE_FILE_HEADER = """\
# Copyright 2022 The ChromiumOS Authors.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# !! Autogenerated by `populate-workspace.py`; please don't edit. !!

"""


def main(argv: List[str]):
    logging.basicConfig(
        format=">> %(asctime)s: %(levelname)s: %(filename)s:%(lineno)d: "
        "%(message)s",
        level=logging.INFO,
    )

    projects_dir = Path(__file__).resolve().parent
    projects = []
    for dir_path, subdirs, files in os.walk(projects_dir):
        if "Cargo.toml" not in files:
            continue

        dir_path = Path(dir_path)
        if dir_path == projects_dir:
            continue

        projects.append(dir_path.relative_to(projects_dir))

        # It's a waste to descend into src directories.
        if "src" in subdirs:
            del subdirs[subdirs.index("src")]
        else:
            # ...Though if src/ doesn't exist, Cargo will get confused.
            # Synthesize one with a nop lib.rs.
            src = dir_path / "src"
            src.mkdir()
            (src / "lib.rs").write_bytes(b"")
            logging.info("Synthesized src/lib.rs for %s", dir_path)

    assert projects, f"No projects found under {projects_dir}"
    projects.sort()

    logging.info("Identified %d projects", len(projects))

    workspace_toml_file = projects_dir / "Cargo.toml"
    with workspace_toml_file.open("w", encoding="utf-8") as f:
        f.write(WORKSPACE_FILE_HEADER)
        # The `toml` crate writes this as a massive line, which is hard to
        # read. Since this is simple to write, write it directly.
        # TODO(b/242668603): find a toml crate with prettier formatting
        f.write('[workspace]\nmembers = [\n')
        for project in projects:
            project = str(project)
            assert '"' not in project and "\\" not in project, project
            f.write(f'    "{project}",\n')
        f.write("]")

    logging.info("Workspace Cargo.toml successfully written.")


if __name__ == "__main__":
    sys.exit(main(sys.argv[1:]))