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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.jena.atlas.lib;
import static org.apache.jena.atlas.lib.Lib.hashCodeObject ;
import static org.apache.jena.atlas.lib.StrUtils.str ;
import java.util.Objects;
public class Pair<A, B>
{
public static <L, R> Pair<L,R> create(L x, R y) { return new Pair<>(x,y) ; }
final A a ;
final B b ;
public Pair(A a, B b) { this.a = a; this.b = b ; }
public A getLeft() { return a ; }
public B getRight() { return b ; }
public A car() { return a ; }
public B cdr() { return b ; }
@Override
public int hashCode()
{
return hashCodeObject(car()) ^ hashCodeObject(cdr())<<1 ;
}
@Override
public boolean equals(Object other)
{
if ( this == other ) return true ;
// If it's a pair of a different <A,B> then .equals
// Pair<A,B>(null,null) is equal to Pair<C,D>(null ,null)
// Type erasure makes this hard to check otherwise.
// Use class X extends Pair<A,B> and implement .equals to do
// instanceof then call super.equals.
if( ! ( other instanceof Pair<?,?> ) ) return false ;
Pair<?,?> p2 = (Pair<?,?>)other ;
return Objects.equals(car(), p2.car()) && Objects.equals(cdr(), p2.cdr()) ;
}
/** Test whether the arguments are equal to the elements of this pair */
public boolean equalElts(A left, B right) {
return Objects.equals(car(), left) && Objects.equals(cdr(), right) ;
}
@Override
public String toString() { return "("+str(a)+", "+str(b)+")" ; }
}
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