com.facebook.buck.parser.ParserPythonInterpreterProvider.java Source code

Introduction

Here is the source code for com.facebook.buck.parser.ParserPythonInterpreterProvider.java

Source

/*
 * Copyright 2017-present Facebook, Inc.
 *
 * 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.
 */

package com.facebook.buck.parser;

import com.facebook.buck.core.config.BuckConfig;
import com.facebook.buck.core.exceptions.HumanReadableException;
import com.facebook.buck.io.ExecutableFinder;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Optional;

public class ParserPythonInterpreterProvider {

    private static final ImmutableList<String> PYTHON_INTERPRETER_NAMES = ImmutableList.of("python2", "python");

    private final ParserConfig parserConfig;
    private final ExecutableFinder executableFinder;

    public ParserPythonInterpreterProvider(BuckConfig buckConfig, ExecutableFinder executableFinder) {
        this(buckConfig.getView(ParserConfig.class), executableFinder);
    }

    public ParserPythonInterpreterProvider(ParserConfig parserConfig, ExecutableFinder executableFinder) {
        this.parserConfig = parserConfig;
        this.executableFinder = executableFinder;
    }

    /**
     * Returns the path to python interpreter. If python is specified in the 'python_interpreter' key
     * of the 'parser' section that is used and an error reported if invalid.
     *
     * <p>If none has been specified, consult the PythonBuckConfig for an interpreter.
     *
     * @return The found python interpreter.
     */
    public String getOrFail() {
        Path path = getPythonInterpreter(parserConfig.getParserPythonInterpreterPath());
        if (!(Files.isExecutable(path) && !Files.isDirectory(path))) {
            throw new HumanReadableException("Not a python executable: " + path);
        }
        return path.toString();
    }

    private Path findInterpreter(ImmutableList<String> interpreterNames) {
        Preconditions.checkArgument(!interpreterNames.isEmpty());
        for (String interpreterName : interpreterNames) {
            Optional<Path> python = executableFinder.getOptionalExecutable(Paths.get(interpreterName),
                    parserConfig.getDelegate().getEnvironment());
            if (python.isPresent()) {
                return python.get().toAbsolutePath();
            }
        }
        throw new HumanReadableException("No python interpreter found (searched %s).",
                Joiner.on(", ").join(interpreterNames));
    }

    /**
     * Returns the path to python interpreter. If python is specified in 'interpreter' key of the
     * 'python' section that is used and an error reported if invalid.
     *
     * @return The found python interpreter.
     */
    private Path getPythonInterpreter(Optional<String> interpreterPath) {
        if (!interpreterPath.isPresent()) {
            return findInterpreter(PYTHON_INTERPRETER_NAMES);
        }
        Path configPath = Paths.get(interpreterPath.get());
        if (!configPath.isAbsolute()) {
            return findInterpreter(ImmutableList.of(interpreterPath.get()));
        }
        return configPath;
    }
}