org.eclipse.jdt.internal.compiler.codegen.CharArrayCache Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of ecj Show documentation
Show all versions of ecj Show documentation
This is Eclipse JDT Core Batch Compiler used by Scout SDK
The newest version!
/*******************************************************************************
* Copyright (c) 2000, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.codegen;
import org.eclipse.jdt.core.compiler.CharOperation;
public class CharArrayCache {
// to avoid using Enumerations, walk the individual tables skipping nulls
public char[] keyTable[];
public int valueTable[];
int elementSize; // number of elements in the table
int threshold;
/**
* Constructs a new, empty hashtable. A default capacity is used.
* Note that the hashtable will automatically grow when it gets full.
*/
public CharArrayCache() {
this(9);
}
/**
* Constructs a new, empty hashtable with the specified initial
* capacity.
* @param initialCapacity int
* the initial number of buckets; must be less than Integer.MAX_VALUE / 2
*/
public CharArrayCache(int initialCapacity) {
this.elementSize = 0;
this.threshold = (initialCapacity * 2) / 3; // faster than float operation
this.keyTable = new char[initialCapacity][];
this.valueTable = new int[initialCapacity];
}
/**
* Clears the hash table so that it has no more elements in it.
*/
public void clear() {
for (int i = this.keyTable.length; --i >= 0;) {
this.keyTable[i] = null;
this.valueTable[i] = 0;
}
this.elementSize = 0;
}
/** Returns true if the collection contains an element for the key.
*
* @param key char[] the key that we are looking for
* @return boolean
*/
public boolean containsKey(char[] key) {
int length = this.keyTable.length, index = CharOperation.hashCode(key) % length;
while (this.keyTable[index] != null) {
if (CharOperation.equals(this.keyTable[index], key))
return true;
if (++index == length) { // faster than modulo
index = 0;
}
}
return false;
}
/** Gets the object associated with the specified key in the
* hashtable.
* @param key char[] the specified key
* @return int the element for the key or -1 if the key is not
* defined in the hash table.
*/
public int get(char[] key) {
int length = this.keyTable.length, index = CharOperation.hashCode(key) % length;
while (this.keyTable[index] != null) {
if (CharOperation.equals(this.keyTable[index], key))
return this.valueTable[index];
if (++index == length) { // faster than modulo
index = 0;
}
}
return -1;
}
/**
* Puts the specified element into the hashtable if it wasn't there already,
* using the specified key. The element may be retrieved by doing a get() with the same key.
* The key and the element cannot be null.
*
* @param key the given key in the hashtable
* @param value the given value
* @return int the old value of the key, or -value if it did not have one.
*/
public int putIfAbsent(char[] key, int value) {
int length = this.keyTable.length, index = CharOperation.hashCode(key) % length;
while (this.keyTable[index] != null) {
if (CharOperation.equals(this.keyTable[index], key))
return this.valueTable[index];
if (++index == length) { // faster than modulo
index = 0;
}
}
this.keyTable[index] = key;
this.valueTable[index] = value;
// assumes the threshold is never equal to the size of the table
if (++this.elementSize > this.threshold)
rehash();
return -value; // negative when added (value is assumed to be > 0)
}
/**
* Puts the specified element into the hashtable, using the specified
* key. The element may be retrieved by doing a get() with the same key.
* The key and the element cannot be null.
*
* @param key Object the specified key in the hashtable
* @param value int the specified element
* @return int the old value of the key, or -1 if it did not have one.
*/
private int put(char[] key, int value) {
int length = this.keyTable.length, index = CharOperation.hashCode(key) % length;
while (this.keyTable[index] != null) {
if (CharOperation.equals(this.keyTable[index], key))
return this.valueTable[index] = value;
if (++index == length) { // faster than modulo
index = 0;
}
}
this.keyTable[index] = key;
this.valueTable[index] = value;
// assumes the threshold is never equal to the size of the table
if (++this.elementSize > this.threshold)
rehash();
return value;
}
/**
* Rehashes the content of the table into a bigger table.
* This method is called automatically when the hashtable's
* size exceeds the threshold.
*/
private void rehash() {
CharArrayCache newHashtable = new CharArrayCache(this.keyTable.length * 2);
for (int i = this.keyTable.length; --i >= 0;)
if (this.keyTable[i] != null)
newHashtable.put(this.keyTable[i], this.valueTable[i]);
this.keyTable = newHashtable.keyTable;
this.valueTable = newHashtable.valueTable;
this.threshold = newHashtable.threshold;
}
/** Remove the object associated with the specified key in the
* hashtable.
* @param key char[] the specified key
*/
public void remove(char[] key) {
int length = this.keyTable.length, index = CharOperation.hashCode(key) % length;
while (this.keyTable[index] != null) {
if (CharOperation.equals(this.keyTable[index], key)) {
this.valueTable[index] = 0;
this.keyTable[index] = null;
return;
}
if (++index == length) { // faster than modulo
index = 0;
}
}
}
/**
* Returns the key corresponding to the value. Returns null if the
* receiver doesn't contain the value.
* @param value int the value that we are looking for
* @return Object
*/
public char[] returnKeyFor(int value) {
for (int i = this.keyTable.length; i-- > 0;) {
if (this.valueTable[i] == value) {
return this.keyTable[i];
}
}
return null;
}
/**
* Returns the number of elements contained in the hashtable.
*
* @return int The size of the table
*/
public int size() {
return this.elementSize;
}
/**
* Converts to a rather lengthy String.
*
* return String the ascii representation of the receiver
*/
public String toString() {
int max = size();
StringBuffer buf = new StringBuffer();
buf.append("{"); //$NON-NLS-1$
for (int i = 0; i < max; ++i) {
if (this.keyTable[i] != null) {
buf.append(this.keyTable[i]).append("->").append(this.valueTable[i]); //$NON-NLS-1$
}
if (i < max) {
buf.append(", "); //$NON-NLS-1$
}
}
buf.append("}"); //$NON-NLS-1$
return buf.toString();
}
}