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1#!/usr/bin/env python3
2# Copyright 2020 The Pigweed Authors
3#
4# Licensed under the Apache License, Version 2.0 (the "License"); you may not
5# use this file except in compliance with the License. You may obtain a copy of
6# the License at
7#
8#     https://www.apache.org/licenses/LICENSE-2.0
9#
10# Unless required by applicable law or agreed to in writing, software
11# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13# License for the specific language governing permissions and limitations under
14# the License.
15"""pw_protobuf compiler plugin.
16
17This file implements a protobuf compiler plugin which generates C++ headers for
18protobuf messages in the pw_protobuf format.
19"""
20
21import sys
22from argparse import ArgumentParser, Namespace
23from pathlib import Path
24from shlex import shlex
25
26from google.protobuf.compiler import plugin_pb2
27
28from pw_protobuf import codegen_pwpb, options
29
30
31def parse_parameter_options(parameter: str) -> Namespace:
32    """Parses parameters passed through from protoc.
33
34    These parameters come in via passing `--${NAME}_out` parameters to protoc,
35    where protoc-gen-${NAME} is the supplied name of the plugin. At time of
36    writing, Blaze uses --pwpb_opt, whereas the script for GN uses --custom_opt.
37    """
38    parser = ArgumentParser()
39    parser.add_argument(
40        '-I',
41        '--include-path',
42        dest='include_paths',
43        metavar='DIR',
44        action='append',
45        default=[],
46        type=Path,
47        help='Append DIR to options file search path',
48    )
49    parser.add_argument(
50        '--no-legacy-namespace',
51        dest='no_legacy_namespace',
52        action='store_true',
53        help='If set, suppresses `using namespace` declarations, which '
54        'disallows use of the legacy non-prefixed namespace',
55    )
56    parser.add_argument(
57        '--exclude-legacy-snake-case-field-name-enums',
58        dest='exclude_legacy_snake_case_field_name_enums',
59        action='store_true',
60        help='Do not generate legacy SNAKE_CASE names for field name enums.',
61    )
62
63    # protoc passes the custom arguments in shell quoted form, separated by
64    # commas. Use shlex to split them, correctly handling quoted sections, with
65    # equivalent options to IFS=","
66    lex = shlex(parameter)
67    lex.whitespace_split = True
68    lex.whitespace = ','
69    lex.commenters = ''
70    args = list(lex)
71
72    return parser.parse_args(args)
73
74
75def process_proto_request(
76    req: plugin_pb2.CodeGeneratorRequest, res: plugin_pb2.CodeGeneratorResponse
77) -> None:
78    """Handles a protoc CodeGeneratorRequest message.
79
80    Generates code for the files in the request and writes the output to the
81    specified CodeGeneratorResponse message.
82
83    Args:
84      req: A CodeGeneratorRequest for a proto compilation.
85      res: A CodeGeneratorResponse to populate with the plugin's output.
86    """
87    args = parse_parameter_options(req.parameter)
88    for proto_file in req.proto_file:
89        proto_options = options.load_options(
90            args.include_paths, Path(proto_file.name)
91        )
92        output_files = codegen_pwpb.process_proto_file(
93            proto_file,
94            proto_options,
95            suppress_legacy_namespace=args.no_legacy_namespace,
96            exclude_legacy_snake_case_field_name_enums=(
97                args.exclude_legacy_snake_case_field_name_enums
98            ),
99        )
100        for output_file in output_files:
101            fd = res.file.add()
102            fd.name = output_file.name()
103            fd.content = output_file.content()
104
105
106def main() -> int:
107    """Protobuf compiler plugin entrypoint.
108
109    Reads a CodeGeneratorRequest proto from stdin and writes a
110    CodeGeneratorResponse to stdout.
111    """
112    data = sys.stdin.buffer.read()
113    request = plugin_pb2.CodeGeneratorRequest.FromString(data)
114    response = plugin_pb2.CodeGeneratorResponse()
115    process_proto_request(request, response)
116
117    # Declare that this plugin supports optional fields in proto3.
118    response.supported_features |= (  # type: ignore[attr-defined]
119        response.FEATURE_PROTO3_OPTIONAL
120    )  # type: ignore[attr-defined]
121
122    sys.stdout.buffer.write(response.SerializeToString())
123    return 0
124
125
126if __name__ == '__main__':
127    sys.exit(main())
128