org.apache.hadoop.util.Options.java Source code

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Here is the source code for org.apache.hadoop.util.Options.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with this
 * work for additional information regarding copyright ownership. The ASF
 * licenses this file to you 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 org.apache.hadoop.util;

import java.io.IOException;
import java.util.Arrays;

import org.apache.hadoop.fs.FSDataInputStream;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.Path;

/**
 * This class allows generic access to variable length type-safe parameter
 * lists.
 */
public class Options {

    public static abstract class StringOption {
        private final String value;

        protected StringOption(String value) {
            this.value = value;
        }

        public String getValue() {
            return value;
        }
    }

    public static abstract class ClassOption {
        private final Class<?> value;

        protected ClassOption(Class<?> value) {
            this.value = value;
        }

        public Class<?> getValue() {
            return value;
        }
    }

    public static abstract class BooleanOption {
        private final boolean value;

        protected BooleanOption(boolean value) {
            this.value = value;
        }

        public boolean getValue() {
            return value;
        }
    }

    public static abstract class IntegerOption {
        private final int value;

        protected IntegerOption(int value) {
            this.value = value;
        }

        public int getValue() {
            return value;
        }
    }

    public static abstract class LongOption {
        private final long value;

        protected LongOption(long value) {
            this.value = value;
        }

        public long getValue() {
            return value;
        }
    }

    public static abstract class PathOption {
        private final Path value;

        protected PathOption(Path value) {
            this.value = value;
        }

        public Path getValue() {
            return value;
        }
    }

    public static abstract class FSDataInputStreamOption {
        private final FSDataInputStream value;

        protected FSDataInputStreamOption(FSDataInputStream value) {
            this.value = value;
        }

        public FSDataInputStream getValue() {
            return value;
        }
    }

    public static abstract class FSDataOutputStreamOption {
        private final FSDataOutputStream value;

        protected FSDataOutputStreamOption(FSDataOutputStream value) {
            this.value = value;
        }

        public FSDataOutputStream getValue() {
            return value;
        }
    }

    public static abstract class ProgressableOption {
        private final Progressable value;

        protected ProgressableOption(Progressable value) {
            this.value = value;
        }

        public Progressable getValue() {
            return value;
        }
    }

    /**
     * Find the first option of the required class.
     * @param <T> the static class to find
     * @param <base> the parent class of the array
     * @param cls the dynamic class to find
     * @param opts the list of options to look through
     * @return the first option that matches
     * @throws IOException
     */
    @SuppressWarnings("unchecked")
    public static <base, T extends base> T getOption(Class<T> cls, base[] opts) throws IOException {
        for (base o : opts) {
            if (o.getClass() == cls) {
                return (T) o;
            }
        }
        return null;
    }

    /**
     * Prepend some new options to the old options
     * @param <T> the type of options
     * @param oldOpts the old options
     * @param newOpts the new options
     * @return a new array of options
     */
    public static <T> T[] prependOptions(T[] oldOpts, T... newOpts) {
        // copy the new options to the front of the array
        T[] result = Arrays.copyOf(newOpts, newOpts.length + oldOpts.length);
        // now copy the old options
        System.arraycopy(oldOpts, 0, result, newOpts.length, oldOpts.length);
        return result;
    }
}