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Open-source constraint solver.
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2022, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.util.iterators;
/**
* An interface to declare values iterator.
*
* A value iterator can be iterated in 2 ways: bottom-up (from lower bound to upper bound)
* and top-down (from upper bound to lower bound).
* To iterate in bottom-up way, first call bottomUpInit(), then hasNext() and next().
* To iterate in bottom-up way, first call topDownInit(), then hasPrevious() and previous().
*
* Once a way is selected, using the wrong methods can lead to unexpected behaviour.
*
*
* ValueIterator vit = ...;
* vit.bottomUpInit();
* while(vit.hasNext()){
* int v = vit.next();
* // operate on value v here
* }
* OR
*
* ValueIterator vit = ...;
* vit.topDownInit();
* while(vit.hasPrevious()){
* int v = vit.previous();
* // operate on value v here
* }
*
* @author Charles Prud'homme
* @since 05/10/11
*/
public interface ValueIterator {
/**
* Prepare iteration from smallest value to highest value (using {@link #hasNext()} / {@link #next()})
*
* ValueIterator vit = ...;
* vit.bottomUpInit();
* while(vit.hasNext()){
* int v = vit.next();
* // operate on value v here
* }
* OR
*
*/
void bottomUpInit();
/**
* Prepare iteration from highest value to smallest value (using {@link #hasPrevious()} / {@link #previous()})
*
* ValueIterator vit = ...;
* vit.topDownInit();
* while(vit.hasPrevious()){
* int v = vit.previous();
* // operate on value v here
* }
*/
void topDownInit();
/**
* Returns true if the iteration has more values. (In other
* words, returns true if next would return valid value.)
*
* ValueIterator vit = ...;
* vit.bottomUpInit();
* while(vit.hasNext()){
* int v = vit.next();
* // operate on value v here
* }
* OR
*
*
* @beware incompatible with {@link #hasPrevious()}
*
* @return true if the getIterator has more values.
*/
boolean hasNext();
/**
* Returns true if the iteration has more ranges. (In other
* words, returns true if previous would return a valid value.)
*
* ValueIterator vit = ...;
* vit.topDownInit();
* while(vit.hasPrevious()){
* int v = vit.previous();
* // operate on value v here
* }
*
* @beware incompatible with {@link #hasNext()}
*
* @return true if the getIterator has more values.
*/
boolean hasPrevious();
/**
* Compute and return the next value.
*
* ValueIterator vit = ...;
* vit.bottomUpInit();
* while(vit.hasNext()){
* int v = vit.next();
* // operate on value v here
* }
* OR
*
*
* @beware incompatible with {@link #previous()}
*
* @return the next element in the iteration.
*/
int next();
/**
* Compute and return the previous value.
*
* ValueIterator vit = ...;
* vit.topDownInit();
* while(vit.hasPrevious()){
* int v = vit.previous();
* // operate on value v here
* }
*
* @beware incompatible with {@link #next()}
*
* @return the previous element in the iteration.
*/
int previous();
}