/*
 * Copyright (c) 2013, OpenCloudDB/MyCAT and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software;Designed and Developed mainly by many Chinese 
 * opensource volunteers. you can redistribute it and/or modify it under the 
 * terms of the GNU General Public License version 2 only, as published by the
 * Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 * 
 * Any questions about this component can be directed to it's project Web address 
 * https://code.google.com/p/opencloudb/.
 *
 */
package org.opencloudb.parser.util;

/**
 * (created at 2010-7-21)
 * 
 * @author mycat
 */
public final class Pair<K, V> {

    private final K key;
    private final V value;

    public Pair(K key, V value) {
        this.key = key;
        this.value = value;
    }

    public K getKey() {
        return key;
    }

    public V getValue() {
        return value;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("(").append(key).append(", ").append(value).append(")");
        return sb.toString();
    }

    private static final int HASH_CONST = 37;

    @Override
    public int hashCode() {
        int hash = 17;
        if (key == null) {
            hash += HASH_CONST;
        } else {
            hash = hash << 5 + hash << 1 + hash + key.hashCode();
        }
        if (value == null) {
            hash += HASH_CONST;
        } else {
            hash = hash << 5 + hash << 1 + hash + value.hashCode();
        }
        return hash;
    }

    @SuppressWarnings("rawtypes")
    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (!(obj instanceof Pair)) return false;
        Pair that = (Pair) obj;
        return isEquals(this.key, that.key) && isEquals(this.value, that.value);
    }

    private boolean isEquals(Object o1, Object o2) {
        if (o1 == o2) return true;
        if (o1 == null) return o2 == null;
        return o1.equals(o2);
    }

}