com.facebook.buck.features.python.toolchain.impl.PythonInterpreterFromConfig.java Source code

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Here is the source code for com.facebook.buck.features.python.toolchain.impl.PythonInterpreterFromConfig.java

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/*
 * 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.features.python.toolchain.impl;

import com.facebook.buck.core.exceptions.HumanReadableException;
import com.facebook.buck.features.python.PythonBuckConfig;
import com.facebook.buck.features.python.toolchain.PythonInterpreter;
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.Path;
import java.nio.file.Paths;
import java.util.Optional;

public class PythonInterpreterFromConfig implements PythonInterpreter {

    // Prefer "python2" where available (Linux), but fall back to "python" (Mac).
    private static final ImmutableList<String> PYTHON_INTERPRETER_NAMES = ImmutableList.of("python2", "python");

    private final PythonBuckConfig pythonBuckConfig;
    private final ExecutableFinder executableFinder;

    public PythonInterpreterFromConfig(PythonBuckConfig pythonBuckConfig, ExecutableFinder executableFinder) {
        this.pythonBuckConfig = pythonBuckConfig;
        this.executableFinder = executableFinder;
    }

    @Override
    public Path getPythonInterpreterPath(String section) {
        return getPythonInterpreter(section);
    }

    @Override
    public Path getPythonInterpreterPath() {
        return getPythonInterpreter(pythonBuckConfig.getDefaultSection());
    }

    private Path findInterpreter(ImmutableList<String> interpreterNames) {
        Preconditions.checkArgument(!interpreterNames.isEmpty());
        for (String interpreterName : interpreterNames) {
            Optional<Path> python = executableFinder.getOptionalExecutable(Paths.get(interpreterName),
                    pythonBuckConfig.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(String section) {
        Optional<String> pathToInterpreter = pythonBuckConfig.getInterpreter(section);
        if (!pathToInterpreter.isPresent()) {
            return findInterpreter(PYTHON_INTERPRETER_NAMES);
        }
        Path configPath = Paths.get(pathToInterpreter.get());
        if (!configPath.isAbsolute()) {
            return findInterpreter(ImmutableList.of(pathToInterpreter.get()));
        }
        return configPath;
    }
}