harp.util.FileUtil.java Source code

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Here is the source code for harp.util.FileUtil.java

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/*
 * Copyright 2014 Yash Parghi
 *
 * 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 harp.util;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;

import java.io.File;
import java.nio.file.Files;
import java.nio.file.Path;

/**
 * Static utility methods for file operations.
 */
public final class FileUtil {

    /**
     * Find a file with the given base name, searching upward from the given starting directory.
     *
     * @param filename the base filename to look for
     * @param startingPath the starting directory to search upward from
     *
     * @return an {@code Optional} containing the Path of the file if found, or an empty Optional
     *     otherwise
     */
    public static Optional<Path> findUpward(String filename, Path startingPath) {
        Preconditions.checkNotNull(filename);
        Preconditions.checkArgument(!filename.contains(File.separator));
        Preconditions.checkArgument(Files.isDirectory(startingPath));
        Path possibleRootDir = startingPath;
        while (possibleRootDir != null) {
            Path possiblePath = possibleRootDir.resolve(filename);
            if (Files.isRegularFile(possiblePath)) {
                return Optional.of(possiblePath);
            } else {
                possibleRootDir = possibleRootDir.getParent();
            }
        }
        return Optional.absent();
    }
}