/*
* 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.openjpa.persistence.test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Generates combinations given multiple choices in each dimension.
*
* Usage:
* <code>
* CombinationGenerator combo = new CombinationGenerator();
* combo.addDimension(new String[]{"A","B","C"});
* combo.addDimension(new int[]{1,2});
* List[] combos = combo.generate();
* </code>
* will generate 3*2=6 combinations
* <code>
* combos[0] => List("A",1);
* combos[1] => List("B",1);
* combos[2] => List("C",1);
* combos[3] => List("A",2);
* combos[4] => List("B",2);
* combos[5] => List("C",2);
* </code>
*
* @author Pinaki Poddar
*
*/
public class CombinationGenerator {
private List<List> dimensions = new ArrayList();
/**
* Adds a dimension. null or empty argument has no effect.
*/
public void addDimension(List dim) {
if (dim == null || dim.isEmpty())
return;
dimensions.add(dim);
}
/**
* Adds a dimension. null or empty argument has no effect.
*/
public void addDimension(Object[] dim) {
if (dim == null || dim.length == 0)
return;
dimensions.add(Arrays.asList(dim));
}
/**
* Generates all combinations.
* Each array element is a list which has elements in the same order as
* the dimensions were added.
*/
public List[] generate() {
int comboSize = getSize();
int dimsSize = dimensions.size();
List[] result = new ArrayList[comboSize];
for (int i = 0; i < comboSize; i++) {
ArrayList elem = new ArrayList(dimsSize);
for (int j=0; j < dimsSize; j++)
elem.add(null);
result[i] = elem;
}
int dimRepeatingStep = 1;
for (int dimIndex = 0; dimIndex < dimsSize; dimIndex++) {
List dimValueList = dimensions.get(dimIndex);
int valuListSize = dimValueList.size();
for (int j = 0; j < comboSize; j++) {
result[j].set(dimIndex, dimValueList.get((j / dimRepeatingStep)
% valuListSize));
}
dimRepeatingStep *= valuListSize;
}
return result;
}
/**
* Gets the total number of combinations generated. The total number is
* the product of cardinality of each dimension.
*
*/
public int getSize() {
int size = 1;
for (List d : dimensions)
size *= d.size();
return size;
}
}