From 19894ffa53bcc7bc55f936962a55af2bcba1d9e2 Mon Sep 17 00:00:00 2001
From: Nick Burch <nick@apache.org>
Date: Sun, 2 Jul 2006 15:21:12 +0000
Subject: [PATCH] Helper method for when moving stuff about in an array, plus
 test

git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@418607 13f79535-47bb-0310-9956-ffa450edef68
---
 src/java/org/apache/poi/util/ArrayUtil.java   |  58 +++-
 .../org/apache/poi/util/TestArrayUtil.java    | 291 ++++++++++++++++++
 2 files changed, 348 insertions(+), 1 deletion(-)
 create mode 100644 src/testcases/org/apache/poi/util/TestArrayUtil.java

diff --git a/src/java/org/apache/poi/util/ArrayUtil.java b/src/java/org/apache/poi/util/ArrayUtil.java
index 1d05a5ff3..9de24f02d 100644
--- a/src/java/org/apache/poi/util/ArrayUtil.java
+++ b/src/java/org/apache/poi/util/ArrayUtil.java
@@ -47,5 +47,61 @@ public class ArrayUtil
         System.arraycopy( src, src_position, dst, dst_position, length);
     }
 
-
+    /**
+     * Moves a number of entries in an array to another point in the array,
+     *  shifting those inbetween as required.
+     * @param array The array to alter
+     * @param moveFrom The (0 based) index of the first entry to move
+     * @param moveTo The (0 based) index of the positition to move to
+     * @param numToMove The number of entries to move
+     */
+    public static void arrayMoveWithin(Object[] array, int moveFrom, int moveTo, int numToMove) {
+    	// If we're not asked to do anything, return now
+    	if(numToMove <= 0) { return; }
+    	if(moveFrom == moveTo) { return; }
+    	
+    	// Check that the values supplied are valid
+    	if(moveFrom < 0 || moveFrom >= array.length) {
+    		throw new IllegalArgumentException("The moveFrom must be a valid array index");
+    	}
+    	if(moveTo < 0 || moveTo >= array.length) {
+    		throw new IllegalArgumentException("The moveTo must be a valid array index");
+    	}
+    	if(moveFrom+numToMove > array.length) {
+    		throw new IllegalArgumentException("Asked to move more entries than the array has");
+    	}
+    	if(moveTo+numToMove > array.length) {
+    		throw new IllegalArgumentException("Asked to move to a position that doesn't have enough space");
+    	}
+    	
+    	// Grab the bit to move 
+    	Object[] toMove = new Object[numToMove];
+    	System.arraycopy(array, moveFrom, toMove, 0, numToMove);
+    	
+    	// Grab the bit to be shifted
+    	Object[] toShift;
+    	int shiftTo;
+    	if(moveFrom > moveTo) {
+    		// Moving to an earlier point in the array
+    		// Grab everything between the two points
+    		toShift = new Object[(moveFrom-moveTo)];
+    		System.arraycopy(array, moveTo, toShift, 0, toShift.length);
+    		shiftTo = moveTo + numToMove;
+    	} else {
+    		// Moving to a later point in the array
+    		// Grab everything from after the toMove block, to the new point
+    		toShift = new Object[(moveTo-moveFrom)];
+    		System.arraycopy(array, moveFrom+numToMove, toShift, 0, toShift.length);
+    		shiftTo = moveFrom;
+    	}
+    	
+    	// Copy the moved block to its new location
+    	System.arraycopy(toMove, 0, array, moveTo, toMove.length);
+    	
+    	// And copy the shifted block to the shifted location
+    	System.arraycopy(toShift, 0, array, shiftTo, toShift.length);
+    	
+    	
+    	// We're done - array will now have everything moved as required
+    }
 }
diff --git a/src/testcases/org/apache/poi/util/TestArrayUtil.java b/src/testcases/org/apache/poi/util/TestArrayUtil.java
new file mode 100644
index 000000000..e2a531dd0
--- /dev/null
+++ b/src/testcases/org/apache/poi/util/TestArrayUtil.java
@@ -0,0 +1,291 @@
+
+/* ====================================================================
+   Copyright 2002-2004   Apache Software Foundation
+
+   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 org.apache.poi.util;
+
+import junit.framework.*;
+
+/**
+ * Unit test for ArrayUtil
+ *
+ * @author Nick Burch
+ */
+public class TestArrayUtil extends TestCase
+{
+	/**
+	 * Test to ensure that our own arraycopy behaves as it should do
+	 */
+	public void testarraycopy() {
+		byte[] bytes = new byte[] { 0x01, 0x02, 0x03, 0x04 };
+		
+		// Test copy whole thing
+		byte[] dest = new byte[4];
+		ArrayUtil.arraycopy(bytes, 0, dest, 0, 4);
+		
+		assertEquals(dest.length, bytes.length);
+		for(int i=0; i<dest.length; i++) {
+			assertEquals(bytes[i], dest[i]);
+		}
+		
+		// ToDo - test exceptions are as expected
+	}
+	
+	
+	/**
+	 * Helper for testArrayMoveWithin 
+	 */
+	private Integer[] getIntsList() { 
+		return new Integer[] {
+				new Integer(0),
+				new Integer(1),
+				new Integer(2),
+				new Integer(3),
+				new Integer(4),
+				new Integer(5),
+				new Integer(6),
+				new Integer(7),
+				new Integer(8),
+				new Integer(9)
+		};
+	}
+	
+	/**
+	 * Test to ensure that arrayMoveWithin works as expected
+	 */
+	public void testArrayMoveWithin() {
+		Integer[] ints = getIntsList();
+		
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(2), ints[2]);
+		assertEquals(new Integer(3), ints[3]);
+		assertEquals(new Integer(4), ints[4]);
+		assertEquals(new Integer(5), ints[5]);
+		assertEquals(new Integer(6), ints[6]);
+		assertEquals(new Integer(7), ints[7]);
+		assertEquals(new Integer(8), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		
+		//
+		// Moving to a later point in the array
+		//
+		
+		// Shift 1 back
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 4, 8, 1);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(2), ints[2]);
+		assertEquals(new Integer(3), ints[3]);
+		assertEquals(new Integer(5), ints[4]);
+		assertEquals(new Integer(6), ints[5]);
+		assertEquals(new Integer(7), ints[6]);
+		assertEquals(new Integer(8), ints[7]);
+		assertEquals(new Integer(4), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		// Shift front 1 back
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 0, 7, 1);
+		assertEquals(new Integer(1), ints[0]);
+		assertEquals(new Integer(2), ints[1]);
+		assertEquals(new Integer(3), ints[2]);
+		assertEquals(new Integer(4), ints[3]);
+		assertEquals(new Integer(5), ints[4]);
+		assertEquals(new Integer(6), ints[5]);
+		assertEquals(new Integer(7), ints[6]);
+		assertEquals(new Integer(0), ints[7]);
+		assertEquals(new Integer(8), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		// Shift 1 to end
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 4, 9, 1);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(2), ints[2]);
+		assertEquals(new Integer(3), ints[3]);
+		assertEquals(new Integer(5), ints[4]);
+		assertEquals(new Integer(6), ints[5]);
+		assertEquals(new Integer(7), ints[6]);
+		assertEquals(new Integer(8), ints[7]);
+		assertEquals(new Integer(9), ints[8]);
+		assertEquals(new Integer(4), ints[9]);
+
+				
+		//
+		// Moving to an earlier point in the array
+		//
+		
+		// Shift 1 forward
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 8, 3, 1);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(2), ints[2]);
+		assertEquals(new Integer(8), ints[3]);
+		assertEquals(new Integer(3), ints[4]);
+		assertEquals(new Integer(4), ints[5]);
+		assertEquals(new Integer(5), ints[6]);
+		assertEquals(new Integer(6), ints[7]);
+		assertEquals(new Integer(7), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		// Shift end 1 forward
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 9, 2, 1);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(9), ints[2]);
+		assertEquals(new Integer(2), ints[3]);
+		assertEquals(new Integer(3), ints[4]);
+		assertEquals(new Integer(4), ints[5]);
+		assertEquals(new Integer(5), ints[6]);
+		assertEquals(new Integer(6), ints[7]);
+		assertEquals(new Integer(7), ints[8]);
+		assertEquals(new Integer(8), ints[9]);
+		
+		// Shift 1 to front
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 5, 0, 1);
+		assertEquals(new Integer(5), ints[0]);
+		assertEquals(new Integer(0), ints[1]);
+		assertEquals(new Integer(1), ints[2]);
+		assertEquals(new Integer(2), ints[3]);
+		assertEquals(new Integer(3), ints[4]);
+		assertEquals(new Integer(4), ints[5]);
+		assertEquals(new Integer(6), ints[6]);
+		assertEquals(new Integer(7), ints[7]);
+		assertEquals(new Integer(8), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+
+		
+		//
+		// Moving many to a later point in the array
+		//
+		
+		// Shift 3 back
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 2, 6, 3);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(5), ints[2]);
+		assertEquals(new Integer(6), ints[3]);
+		assertEquals(new Integer(7), ints[4]);
+		assertEquals(new Integer(8), ints[5]);
+		assertEquals(new Integer(2), ints[6]);
+		assertEquals(new Integer(3), ints[7]);
+		assertEquals(new Integer(4), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		// Shift 3 to back
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 2, 7, 3);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(5), ints[2]);
+		assertEquals(new Integer(6), ints[3]);
+		assertEquals(new Integer(7), ints[4]);
+		assertEquals(new Integer(8), ints[5]);
+		assertEquals(new Integer(9), ints[6]);
+		assertEquals(new Integer(2), ints[7]);
+		assertEquals(new Integer(3), ints[8]);
+		assertEquals(new Integer(4), ints[9]);
+		
+		// Shift from 3 front
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 0, 5, 3);
+		assertEquals(new Integer(3), ints[0]);
+		assertEquals(new Integer(4), ints[1]);
+		assertEquals(new Integer(5), ints[2]);
+		assertEquals(new Integer(6), ints[3]);
+		assertEquals(new Integer(7), ints[4]);
+		assertEquals(new Integer(0), ints[5]);
+		assertEquals(new Integer(1), ints[6]);
+		assertEquals(new Integer(2), ints[7]);
+		assertEquals(new Integer(8), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		
+		//
+		// Moving many to an earlier point in the array
+		//
+		
+		// Shift 3 forward
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 6, 2, 3);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(6), ints[2]);
+		assertEquals(new Integer(7), ints[3]);
+		assertEquals(new Integer(8), ints[4]);
+		assertEquals(new Integer(2), ints[5]);
+		assertEquals(new Integer(3), ints[6]);
+		assertEquals(new Integer(4), ints[7]);
+		assertEquals(new Integer(5), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		// Shift 3 to front
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 6, 0, 3);
+		assertEquals(new Integer(6), ints[0]);
+		assertEquals(new Integer(7), ints[1]);
+		assertEquals(new Integer(8), ints[2]);
+		assertEquals(new Integer(0), ints[3]);
+		assertEquals(new Integer(1), ints[4]);
+		assertEquals(new Integer(2), ints[5]);
+		assertEquals(new Integer(3), ints[6]);
+		assertEquals(new Integer(4), ints[7]);
+		assertEquals(new Integer(5), ints[8]);
+		assertEquals(new Integer(9), ints[9]);
+		
+		// Shift from 3 back
+		ints = getIntsList();
+		ArrayUtil.arrayMoveWithin(ints, 7, 3, 3);
+		assertEquals(new Integer(0), ints[0]);
+		assertEquals(new Integer(1), ints[1]);
+		assertEquals(new Integer(2), ints[2]);
+		assertEquals(new Integer(7), ints[3]);
+		assertEquals(new Integer(8), ints[4]);
+		assertEquals(new Integer(9), ints[5]);
+		assertEquals(new Integer(3), ints[6]);
+		assertEquals(new Integer(4), ints[7]);
+		assertEquals(new Integer(5), ints[8]);
+		assertEquals(new Integer(6), ints[9]);
+		
+		
+		// Check can't shift more than we have
+		try {
+			ints = getIntsList();
+			ArrayUtil.arrayMoveWithin(ints, 7, 3, 5);
+			fail();
+		} catch(IllegalArgumentException e) {
+			// Good, we don't have 5 from 7 onwards
+		}
+		
+		// Check can't shift where would overshoot
+		try {
+			ints = getIntsList();
+			ArrayUtil.arrayMoveWithin(ints, 2, 7, 5);
+			fail();
+		} catch(IllegalArgumentException e) {
+			// Good, we can't fit 5 in starting at 7
+		}
+	}
+}
+