org.eclipse.jdt.internal.core.util.HashtableOfArrayToObject.java Source code

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Here is the source code for org.eclipse.jdt.internal.core.util.HashtableOfArrayToObject.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.core.util;

/**
 * Hashtable of {Object[] --> Object }
 */
public final class HashtableOfArrayToObject implements Cloneable {

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

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

    public HashtableOfArrayToObject() {
        this(13);
    }

    public HashtableOfArrayToObject(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 Object[extraRoom];
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        HashtableOfArrayToObject result = (HashtableOfArrayToObject) 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 Object[length];
        System.arraycopy(this.valueTable, 0, result.valueTable, 0, length);
        return result;
    }

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

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

    public int getIndex(Object[] key) {
        int length = this.keyTable.length;
        int index = hashCode(key) % length;
        int keyLength = key.length;
        Object[] currentKey;
        while ((currentKey = this.keyTable[index]) != null) {
            if (currentKey.length == keyLength && Util.equalArraysOrNull(currentKey, key))
                return index;
            if (++index == length) {
                index = 0;
            }
        }
        return -1;
    }

    public Object[] getKey(Object[] key, int keyLength) {
        int length = this.keyTable.length;
        int index = hashCode(key, keyLength) % length;
        Object[] currentKey;
        while ((currentKey = this.keyTable[index]) != null) {
            if (currentKey.length == keyLength && Util.equalArrays(currentKey, key, keyLength))
                return currentKey;
            if (++index == length) {
                index = 0;
            }
        }
        return null;
    }

    private int hashCode(Object[] element) {
        return hashCode(element, element.length);
    }

    private int hashCode(Object[] element, int length) {
        int hash = 0;
        for (int i = length - 1; i >= 0; i--)
            hash = Util.combineHashCodes(hash, element[i].hashCode());
        return hash & 0x7FFFFFFF;
    }

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

    private void rehash() {

        HashtableOfArrayToObject newHashtable = new HashtableOfArrayToObject(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() {
        StringBuffer buffer = new StringBuffer();
        Object[] element;
        for (int i = 0, length = this.keyTable.length; i < length; i++)
            if ((element = this.keyTable[i]) != null) {
                buffer.append('{');
                for (int j = 0, length2 = element.length; j < length2; j++) {
                    buffer.append(element[j]);
                    if (j != length2 - 1)
                        buffer.append(", "); //$NON-NLS-1$
                }
                buffer.append("} -> "); //$NON-NLS-1$
                buffer.append(this.valueTable[i]);
                if (i != length - 1)
                    buffer.append('\n');
            }
        return buffer.toString();
    }
}