org.eclipse.jdt.internal.compiler.util.CharArrayMap Maven / Gradle / Ivy
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/*******************************************************************************
* Copyright (c) 2021 jkubitz and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* jkubitz - initial API and implementation
*******************************************************************************/
package org.eclipse.jdt.internal.compiler.util;
import java.util.Arrays;
import java.util.Collection;
import java.util.Objects;
import java.util.stream.Collectors;
/**
* This map avoids hashing. This is suitable for few elements or long char arrays because it uses vectorized equals.
* Vectorized equals is several times faster then calculating hashCode in a loop. This class is not thread safe and
* callers are responsible for thread safety.
*
* @author jkubitz
*/
public final class CharArrayMap implements CharArrayMapper
{
private char[] keyTable[];
private P valueTable[];
/**
* The number of key-value mappings contained in this map.
*/
private int size;
public CharArrayMap() {
this(0); // usually not very large
}
public CharArrayMap(int estimatedSize) {
int capacity = estimatedSize > 0 ? estimatedSize : 0;
this.size = 0;
this.keyTable = new char[capacity][];
@SuppressWarnings("unchecked")
P[] x = (P[]) new Object[capacity];
this.valueTable = x;
}
@Override
public Collection
values() {
return Arrays.stream(this.valueTable).filter(Objects::nonNull).collect(Collectors.toList());
}
@Override
public Collection keys() {
return Arrays.stream(this.keyTable).filter(Objects::nonNull).collect(Collectors.toList());
}
@Override
public boolean containsKey(char[] key) {
for (int i = 0; i < this.size; i++) {
if (Arrays.equals(this.keyTable[i], key)) {
return true;
}
}
return false;
}
@Override
public P get(char[] key) {
for (int i = 0; i < this.size; i++) {
if (Arrays.equals(this.keyTable[i], key)) {
return this.valueTable[i];
}
}
return null;
}
@Override
public P put(char[] key, P value) {
int i = 0;
for (; i < this.size; i++) {
if (Arrays.equals(this.keyTable[i], key)) {
P previous = this.valueTable[i];
this.valueTable[i] = value;
return previous;
}
}
if (i >= this.keyTable.length) {
grow();
}
this.keyTable[i] = key;
this.valueTable[i] = value;
this.size++;
// assumes the threshold is never equal to the size of the table
return null;
}
void transferTo(CharArrayMapper bigMap) {
for (int i = 0; i < this.size; i++) {
if (this.keyTable[i] != null) {
bigMap.put(this.keyTable[i], this.valueTable[i]);
}
}
}
private void grow() {
int capacity = this.keyTable.length > 1 ? this.keyTable.length : 1;
int newCapacity = capacity * 2;
this.keyTable = Arrays.copyOfRange(this.keyTable, 0, newCapacity);
this.valueTable = Arrays.copyOfRange(this.valueTable, 0, newCapacity);
}
@Override
public int size() {
return this.size;
}
@Override
public String toString() {
return CharArrayMapper.toString(this);
}
}