org.netbeans.editor.GapObjectArray Maven / Gradle / Ivy
/*
* Sun Public License Notice
*
* The contents of this file are subject to the Sun Public License
* Version 1.0 (the "License"). You may not use this file except in
* compliance with the License. A copy of the License is available at
* http://www.sun.com/
*
* The Original Code is NetBeans. The Initial Developer of the Original
* Code is Sun Microsystems, Inc. Portions Copyright 1997-2003 Sun
* Microsystems, Inc. All Rights Reserved.
*/
package org.netbeans.editor;
/**
* Implementation of {@link ObjectArray} that
* contains a gap which helps to speed up inserts/removals
* close to the gap.
* Note that this implementation is not synchronized. If
* multiple threads access an instance of this class concurrently, and at
* least one of the threads inserts/removes items, the whole access must be
* synchronized externally.
*
* @author Miloslav Metelka
* @version 1.00
*/
public class GapObjectArray implements ObjectArray, ObjectArray.CopyItems {
private static final Object[] EMPTY_ARRAY = new Object[0];
/**
* Array holding the elements with the gap starting at the gapStart
* being gapLength long.
*/
private Object[] array;
/** Starting index of the gap in the array. */
private int gapStart;
/** Length of the gap */
private int gapLength;
public GapObjectArray() {
this.array = EMPTY_ARRAY;
}
/**
* Construct new gap array of objects.
* @param array use this array as an initial array for processing.
* The array will be modified by subsequent changes. If the array
* contents should be preserved the array must be cloned first
* before processing.
* @param length length of the valid part of the array that contains
* the objects to be managed. The area must start at the index 0.
*/
public GapObjectArray(Object[] array, int length) {
this.array = array;
this.gapStart = length;
this.gapLength = array.length - length;
}
public int getItemCount() {
return array.length - gapLength;
}
public Object getItem(int index) {
return array[(index < gapStart) ? index : (index + gapLength)];
}
public void copyItems(int srcStartIndex, int srcEndIndex,
Object[] dest, int destIndex) {
rangeCheck(srcStartIndex, srcEndIndex - srcStartIndex);
if (srcEndIndex < gapStart) { // fully below gap
System.arraycopy(array, srcStartIndex,
dest, destIndex, srcEndIndex - srcStartIndex);
} else { // above gap or spans the gap
if (srcStartIndex >= gapStart) { // fully above gap
System.arraycopy(array, srcStartIndex + gapLength, dest, destIndex,
srcEndIndex - srcStartIndex);
} else { // spans gap
int beforeGap = gapStart - srcStartIndex;
System.arraycopy(array, srcStartIndex, dest, destIndex, beforeGap);
System.arraycopy(array, gapStart + gapLength, dest, destIndex + beforeGap,
srcEndIndex - srcStartIndex - beforeGap);
}
}
}
public void replace(int index, int removeCount, Object[] newItems) {
remove(index, removeCount);
insertAll(index, newItems);
}
public void insertItem(int index, Object item) {
indexCheck(index);
if (gapLength == 0) {
enlargeGap(1);
}
if (index != gapStart) {
moveGap(index);
}
array[gapStart++] = item;
gapLength--;
}
public void insertAll(int index, Object[] items) {
insertAll(index, items, 0, items.length);
}
public void insertAll(int index, Object[] items, int off, int len) {
indexCheck(index);
if (items.length == 0) {
return;
}
int extraLength = len - gapLength;
if (extraLength > 0) {
enlargeGap(extraLength);
}
if (index != gapStart) {
moveGap(index);
}
System.arraycopy(items, off, array, gapStart, len);
gapStart += len;
gapLength -= len;
}
public void remove(int index, int count) {
remove(index, count, null);
}
public void remove(int index, int count, RemoveUpdater removeUpdater) {
rangeCheck(index, count);
if (count == 0) {
return;
}
if (index >= gapStart) { // completely over gap
if (index > gapStart) {
moveGap(index);
}
// Allow GC of removed items
index += gapLength; // begining of abandoned area
for (int endIndex = index + count; index < endIndex; index++) {
if (removeUpdater != null) {
removeUpdater.removeUpdate(array[index]);
}
array[index] = null;
}
} else { // completely below gap or spans the gap
int endIndex = index + count;
if (endIndex <= gapStart) {
if (endIndex < gapStart) {
moveGap(endIndex);
}
gapStart = index;
} else { // spans gap: gapStart > index but gapStart - index < count
// Allow GC of removed items
for (int clearIndex = index; clearIndex < gapStart; clearIndex++) {
if (removeUpdater != null) {
removeUpdater.removeUpdate(array[clearIndex]);
}
array[clearIndex] = null;
}
index = gapStart + gapLength; // part above the gap
gapStart = endIndex - count; // original value of index
endIndex += gapLength;
}
// Allow GC of removed items
while (index < endIndex) {
if (removeUpdater != null) {
removeUpdater.removeUpdate(array[index]);
}
array[index++] = null;
}
}
gapLength += count;
}
protected void unoptimizedRemove(int index, int count, RemoveUpdater removeUpdater) {
rangeCheck(index, count);
int endIndex = index + count;
if (gapStart != endIndex) {
moveGap(endIndex);
}
// Null the cleared items to allow possible GC of those objects
for (int i = endIndex - 1; i >= index; i--) {
if (removeUpdater != null) {
removeUpdater.removeUpdate(array[i]);
}
array[i] = null;
}
gapStart = index;
}
public void compact() {
if (gapLength > 0) {
int newLength = array.length - gapLength;
Object[] newArray = new Object[newLength];
int gapEnd = gapStart + gapLength;
System.arraycopy(array, 0, newArray, 0, gapStart);
System.arraycopy(array, gapEnd, newArray, gapStart,
array.length - gapEnd);
array = newArray;
gapStart = array.length;
gapLength = 0;
}
}
protected void movedAboveGapUpdate(Object[] array, int index, int count) {
}
protected void movedBelowGapUpdate(Object[] array, int index, int count) {
}
private void moveGap(int index) {
if (index <= gapStart) { // move gap down
int moveSize = gapStart - index;
System.arraycopy(array, index, array,
gapStart + gapLength - moveSize, moveSize);
clearEmpty(index, Math.min(moveSize, gapLength));
gapStart = index;
movedAboveGapUpdate(array, gapStart + gapLength, moveSize);
} else { // above gap
int gapEnd = gapStart + gapLength;
int moveSize = index - gapStart;
System.arraycopy(array, gapEnd, array, gapStart, moveSize);
if (index < gapEnd) {
clearEmpty(gapEnd, moveSize);
} else {
clearEmpty(index, gapLength);
}
movedBelowGapUpdate(array, gapStart, moveSize);
gapStart += moveSize;
}
}
private void clearEmpty(int index, int length) {
while (--length >= 0) {
array[index++] = null; // allow GC
}
}
private void enlargeGap(int extraLength) {
int newLength = Math.max(4,
Math.max(array.length * 2, array.length + extraLength));
int gapEnd = gapStart + gapLength;
int afterGapLength = (array.length - gapEnd);
int newGapEnd = newLength - afterGapLength;
Object[] newArray = new Object[newLength];
System.arraycopy(array, 0, newArray, 0, gapStart);
System.arraycopy(array, gapEnd, newArray, newGapEnd, afterGapLength);
array = newArray;
gapLength = newGapEnd - gapStart;
}
private void rangeCheck(int index, int count) {
if (index < 0 || count < 0 || index + count > getItemCount()) {
throw new IndexOutOfBoundsException("index=" + index // NOI18N
+ ", count=" + count + ", getItemCount()=" + getItemCount()); // NOI18N
}
}
private void indexCheck(int index) {
if (index > getItemCount()) {
throw new IndexOutOfBoundsException("index=" + index // NOI18N
+ ", getItemCount()=" + getItemCount()); // NOI18N
}
}
/**
* Internal consistency check.
*/
void check() {
if (gapStart < 0 || gapLength < 0
|| gapStart + gapLength > array.length
) {
throw new IllegalStateException();
}
// Check whether the whole gap contains only nulls
for (int i = gapStart + gapLength - 1; i >= gapStart; i--) {
if (array[i] != null) {
throw new IllegalStateException();
}
}
}
public String toStringDetail() {
return "gapStart=" + gapStart + ", gapLength=" + gapLength // NOI18N
+ ", array.length=" + array.length; // NOI18N
}
public interface RemoveUpdater {
public void removeUpdate(Object removedItem);
}
}