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jeremybenn |
/* Pair.java -- A heterogenous pair of objects.
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Copyright (C) 2006
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Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.classpath;
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/**
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* A container for a pair of heterogenous objects.
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*
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* @author Andrew John Hughes (gnu_andrew@member.fsf.org)
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*/
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public class Pair<A,B>
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{
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/**
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* The left-hand side of the pair.
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*/
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private A left;
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/**
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* The right-hand side of the pair.
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*/
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private B right;
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/**
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* Constructs a new pair using the given left and
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* right values.
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*
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* @param left the left-hand side of the pair.
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* @param right the right-hand side of the pair.
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*/
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public Pair(A left, B right)
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{
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this.left = left;
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this.right = right;
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}
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/**
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* Returns the left-hand side of the pair.
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*
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* @return the left-hand value.
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*/
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public A getLeft()
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{
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return left;
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}
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/**
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* Returns the right-hand side of the pair.
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*
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* @return the right-hand value.
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*/
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public B getRight()
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{
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return right;
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}
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/**
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* Returns true if the specified object is also a
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* pair with equivalent left and right values.
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*
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* @param obj the object to compare.
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* @return true if the two are equal.
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*/
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public boolean equals(Object obj)
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{
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if (obj instanceof Pair)
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{
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Pair<A,B> p = (Pair<A,B>) obj;
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A lp = p.getLeft();
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B rp = p.getRight();
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return (lp == null ? left == null : lp.equals(left)) &&
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(rp == null ? right == null : rp.equals(right));
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}
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return false;
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}
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/**
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* Returns a hashcode for the pair, created by the
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* summation of the hashcodes of the left and right
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* hand values.
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*
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* @return a hashcode for the pair.
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*/
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public int hashCode()
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{
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return (left == null ? 0 : left.hashCode())
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+ (right == null ? 0 : right.hashCode());
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}
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}
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