org.eclipse.jdt.internal.compiler.util.HashtableOfObjectToInt.java Source code

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Here is the source code for org.eclipse.jdt.internal.compiler.util.HashtableOfObjectToInt.java

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/*******************************************************************************
 * Copyright (c) 2000, 2009 IBM Corporation 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.compiler.util;

/**
 * Hashtable of {Object --> int }
 */
public final class HashtableOfObjectToInt implements Cloneable {

    // to avoid using Enumerations, walk the individual tables skipping nulls
    public Object[] keyTable;
    public int[] valueTable;

    public int elementSize; // number of elements in the table
    int threshold;

    public HashtableOfObjectToInt() {
        this(13);
    }

    public HashtableOfObjectToInt(int size) {

        this.elementSize = 0;
        this.threshold = size; // size represents the expected number of elements
        int extraRoom = (int) (size * 1.75f);
        if (this.threshold == extraRoom)
            extraRoom++;
        this.keyTable = new Object[extraRoom];
        this.valueTable = new int[extraRoom];
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        HashtableOfObjectToInt result = (HashtableOfObjectToInt) super.clone();
        result.elementSize = this.elementSize;
        result.threshold = this.threshold;

        int length = this.keyTable.length;
        result.keyTable = new Object[length];
        System.arraycopy(this.keyTable, 0, result.keyTable, 0, length);

        length = this.valueTable.length;
        result.valueTable = new int[length];
        System.arraycopy(this.valueTable, 0, result.valueTable, 0, length);
        return result;
    }

    public boolean containsKey(Object key) {
        int length = this.keyTable.length, index = (key.hashCode() & 0x7FFFFFFF) % length;
        Object currentKey;
        while ((currentKey = this.keyTable[index]) != null) {
            if (currentKey.equals(key))
                return true;
            if (++index == length) {
                index = 0;
            }
        }
        return false;
    }

    public int get(Object key) {
        int length = this.keyTable.length, index = (key.hashCode() & 0x7FFFFFFF) % length;
        Object currentKey;
        while ((currentKey = this.keyTable[index]) != null) {
            if (currentKey.equals(key))
                return this.valueTable[index];
            if (++index == length) {
                index = 0;
            }
        }
        return -1;
    }

    public void keysToArray(Object[] array) {
        int index = 0;
        for (int i = 0, length = this.keyTable.length; i < length; i++) {
            if (this.keyTable[i] != null)
                array[index++] = this.keyTable[i];
        }
    }

    public int put(Object key, int value) {
        int length = this.keyTable.length, index = (key.hashCode() & 0x7FFFFFFF) % length;
        Object currentKey;
        while ((currentKey = this.keyTable[index]) != null) {
            if (currentKey.equals(key))
                return this.valueTable[index] = value;
            if (++index == length) {
                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;
    }

    public int removeKey(Object key) {
        int length = this.keyTable.length, index = (key.hashCode() & 0x7FFFFFFF) % length;
        Object currentKey;
        while ((currentKey = this.keyTable[index]) != null) {
            if (currentKey.equals(key)) {
                int value = this.valueTable[index];
                this.elementSize--;
                this.keyTable[index] = null;
                rehash();
                return value;
            }
            if (++index == length) {
                index = 0;
            }
        }
        return -1;
    }

    private void rehash() {

        HashtableOfObjectToInt newHashtable = new HashtableOfObjectToInt(this.elementSize * 2); // double the number of expected elements
        Object currentKey;
        for (int i = this.keyTable.length; --i >= 0;)
            if ((currentKey = this.keyTable[i]) != null)
                newHashtable.put(currentKey, this.valueTable[i]);

        this.keyTable = newHashtable.keyTable;
        this.valueTable = newHashtable.valueTable;
        this.threshold = newHashtable.threshold;
    }

    public int size() {
        return this.elementSize;
    }

    @Override
    public String toString() {
        String s = ""; //$NON-NLS-1$
        Object key;
        for (int i = 0, length = this.keyTable.length; i < length; i++)
            if ((key = this.keyTable[i]) != null)
                s += key + " -> " + this.valueTable[i] + "\n"; //$NON-NLS-2$ //$NON-NLS-1$
        return s;
    }
}