110 lines
5.0 KiB
Java
110 lines
5.0 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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package org.apache.poi.util;
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/**
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* Utility classes for dealing with arrays.
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*
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* @author Glen Stampoultzis
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*/
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public class ArrayUtil
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{
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/**
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* This is really a debugging version of <code>System.arraycopy()</code>.
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* Use it to provide better exception messages when copying arrays around.
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* For production use it's better to use the original for speed.
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*/
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public static void arraycopy(byte[] src, int src_position, byte[] dst, int dst_position, int length)
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{
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if (src_position < 0)
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throw new IllegalArgumentException("src_position was less than 0. Actual value " + src_position);
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if (src_position >= src.length)
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throw new IllegalArgumentException( "src_position was greater than src array size. Tried to write starting at position " + src_position + " but the array length is " + src.length );
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if (src_position + length > src.length)
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throw new IllegalArgumentException("src_position + length would overrun the src array. Expected end at " + (src_position + length) + " actual end at " + src.length);
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if (dst_position < 0)
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throw new IllegalArgumentException("dst_position was less than 0. Actual value " + dst_position);
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if (dst_position >= dst.length)
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throw new IllegalArgumentException( "dst_position was greater than dst array size. Tried to write starting at position " + dst_position + " but the array length is " + dst.length );
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if (dst_position + length > dst.length)
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throw new IllegalArgumentException("dst_position + length would overrun the dst array. Expected end at " + (dst_position + length) + " actual end at " + dst.length);
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System.arraycopy( src, src_position, dst, dst_position, length);
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}
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/**
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* Moves a number of entries in an array to another point in the array,
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* shifting those inbetween as required.
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* @param array The array to alter
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* @param moveFrom The (0 based) index of the first entry to move
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* @param moveTo The (0 based) index of the positition to move to
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* @param numToMove The number of entries to move
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*/
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public static void arrayMoveWithin(Object[] array, int moveFrom, int moveTo, int numToMove) {
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// If we're not asked to do anything, return now
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if(numToMove <= 0) { return; }
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if(moveFrom == moveTo) { return; }
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// Check that the values supplied are valid
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if(moveFrom < 0 || moveFrom >= array.length) {
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throw new IllegalArgumentException("The moveFrom must be a valid array index");
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}
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if(moveTo < 0 || moveTo >= array.length) {
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throw new IllegalArgumentException("The moveTo must be a valid array index");
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}
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if(moveFrom+numToMove > array.length) {
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throw new IllegalArgumentException("Asked to move more entries than the array has");
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}
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if(moveTo+numToMove > array.length) {
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throw new IllegalArgumentException("Asked to move to a position that doesn't have enough space");
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}
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// Grab the bit to move
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Object[] toMove = new Object[numToMove];
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System.arraycopy(array, moveFrom, toMove, 0, numToMove);
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// Grab the bit to be shifted
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Object[] toShift;
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int shiftTo;
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if(moveFrom > moveTo) {
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// Moving to an earlier point in the array
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// Grab everything between the two points
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toShift = new Object[(moveFrom-moveTo)];
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System.arraycopy(array, moveTo, toShift, 0, toShift.length);
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shiftTo = moveTo + numToMove;
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} else {
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// Moving to a later point in the array
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// Grab everything from after the toMove block, to the new point
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toShift = new Object[(moveTo-moveFrom)];
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System.arraycopy(array, moveFrom+numToMove, toShift, 0, toShift.length);
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shiftTo = moveFrom;
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}
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// Copy the moved block to its new location
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System.arraycopy(toMove, 0, array, moveTo, toMove.length);
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// And copy the shifted block to the shifted location
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System.arraycopy(toShift, 0, array, shiftTo, toShift.length);
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// We're done - array will now have everything moved as required
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}
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}
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