scripts/build/builders/gn.py

# Copyright (c) 2021 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 os
import shlex

from .builder import Builder


class GnBuilder(Builder):

    def __init__(self, root, runner):
        """Creates  a generic ninja builder.

        Args:
           root: the root where to run GN into
           runner: what to use to execute shell commands
        """
        super(GnBuilder, self).__init__(root, runner)

        self.build_command = None

    def GnBuildArgs(self):
        """Extra gn build `--args`

        If used, returns a list of arguments.
        """
        return None

    def GnBuildEnv(self):
        """Extra environment variables needed for the GN build to run.

        If used, returns a dictionary of environment variables.
        """
        return None

    def PreBuildCommand(self):
        """Extra steps to run before 'build'"""
        pass

    def PostBuildCommand(self):
        """Extra steps to run after 'build'"""
        pass

    def generate(self):
        cmd = [
            'gn', 'gen', '--check', '--fail-on-unused-args',
            '--export-compile-commands',
            '--root=%s' % self.root
        ]

        extra_args = self.GnBuildArgs()
        if extra_args:
            cmd += ['--args=%s' % ' '.join(extra_args)]

        cmd += [self.output_dir]

        title = 'Generating ' + self.identifier
        extra_env = self.GnBuildEnv()

        if extra_env:
            # convert the command into a bash command that includes
            # setting environment variables
            cmd = [
                'bash', '-c', '\n' + ' '.join(
                    ['%s="%s" \\\n' % (key, value) for key, value in extra_env.items()] +
                    [shlex.join(cmd)]
                )
            ]

        self._Execute(cmd, title=title)

    def _build(self):
        self.PreBuildCommand()

        cmd = ['ninja', '-C', self.output_dir]
        if self.build_command:
            cmd.append(self.build_command)

        self._Execute(cmd, title='Building ' + self.identifier)

        self.PostBuildCommand()