com.ejwa.dinja.utility.ArrayHelper.java Source code

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Here is the source code for com.ejwa.dinja.utility.ArrayHelper.java

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/*
 * Copyright  2011-2012 Ejwa Software. All rights reserved.
 *
 * This file is part of Dinja Engine. Dinja Engine is a OpenGLES2
 * 3D engine with physics support developed for the Android platform.
 *
 * Dinja Engine is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * Dinja Engine is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General
 * Public License along with Dinja Engine. If not, see
 * <http://www.gnu.org/licenses/>.
 */
package com.ejwa.dinja.utility;

import org.apache.commons.lang.ArrayUtils;

/**
 * Class that contains some useful methods for searching for subarrays in arrays. The class has methods that work
 * in a similar fashion to {@link String#indexOf(java.lang.String)} but is adapted for generic arrays and includes some
 * additional features, such as support for wrapping and searching of chunks.
 *
 * @author Adam Waldenberg <adam.waldenberg@ejwa.se>
 * @since 0.1
 */
public final class ArrayHelper {
    private ArrayHelper() {
        /* No instances of this class allowed. */
    }

    /**
     * Returns the index, within an array, of the first occurrence of the specified subarray.
     *
     * @param array An array to search in.
     * @param subArray The subarray for which to search.
     * @return The index within this array of the first occurrence of the specified subarray.
     */
    public static <T> int indexOfSubArray(T[] array, T[] subArray) {
        return indexOfSubArrayChunk(array, subArray, subArray.length);
    }

    /**
     * Returns the index, within a wrapped array, of the first occurrence of the specified subarray. This method works in
     * a similar fashion to {@link #indexOfSubArray(Object[], Object[]) indexOfSubArray(T[], T[])}, but loops through the
     * array twice when searchnig for the subarray.
     *
     * @param array An array to search in.
     * @param subArray The subarray for which to search.
     * @return The index within this array of the first occurrence of the specified subarray.
     * @see #indexOfSubArray(Object[], Object[]) indexOfSubArray(T[], T[])
     */
    public static <T> int indexOfSubArrayWrapped(T[] array, T[] subArray) {
        return indexOfSubArray(ArrayUtils.addAll(array, array), subArray);
    }

    /**
     * Returns the index, within an array, of the first occurrence of one of the specified subarray chunks. This method
     * works in a similar fashion to {@link #indexOfSubArray(Object[], Object[]) indexOfSubArray(T[], T[])}, but searches
     * for chunks of size <code>subArrayChunkSize</code> from the subarray when searching through the array.
     *
     * @param array An array to search in.
     * @param subArray The subarray for which to search from.
     * @param subArrayChunkSize Size of the chunks to pick from the subarray when searching through the array.
     * @return The index within this array of the first occurrence of one of the specified subarray chunks.
     * @see #indexOfSubArray(Object[], Object[]) indexOfSubArray(T[], T[])
     */
    @SuppressWarnings("PMD.DataflowAnomalyAnalysis")
    public static <T> int indexOfSubArrayChunk(T[] array, T[] subArray, int subArrayChunkSize) {
        if (subArray.length < subArrayChunkSize) {
            return -1;
        }

        int matches = 0;
        int matchingIndex = -1;

        for (int i = 0; i < subArray.length; i++) {
            for (int j = 0; j < array.length && i + matches < subArray.length; j++) {
                if (array[j].equals(subArray[i + matches])) {
                    if (matches++ == 0) {
                        matchingIndex = j;
                    }

                    if (matches == subArrayChunkSize) {
                        return matchingIndex;
                    }
                } else {
                    matches = 0;
                }
            }
        }

        return -1;
    }

    /**
     * Returns the index, within a wrapped array, of the first occurrence of one of the specified subarray chunks. This
     * method works in a similar fashion to {@link #indexOfSubArrayWrapped(Object[], Object[]) indexOfSubArrayWrapped(T[], T[])},
     * but searches for chunks of size <code>subArrayChunkSize</code> from the subarray when searching through the array.
     *
     * @param array An array to search in.
     * @param subArray The subarray for which to search from.
     * @param subArrayChunkSize Size of the chunks to pick from the subarray when searching through the array.
     * @return The index within this array of the first occurrence of one of the specified subarray chunks.
     * @see #indexOfSubArrayWrapped(Object[], Object[]) indexOfSubArrayWrapped(T[], T[])
     */
    public static <T> int indexOfSubArrayChunkWrapped(T[] array, T[] subArray, int subArrayChunkSize) {
        return indexOfSubArrayChunk(ArrayUtils.addAll(array, array), subArray, subArrayChunkSize);
    }
}