source: bidspace/src/main/java/geniusweb/bidspace/AllBidsList.java@ 27

package geniusweb.bidspace;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import geniusweb.issuevalue.Bid;
import geniusweb.issuevalue.Domain;
import geniusweb.issuevalue.Value;
import tudelft.utilities.immutablelist.AbstractImmutableList;
import tudelft.utilities.immutablelist.ImmutableList;
import tudelft.utilities.immutablelist.Outer;

/**
 * A list containing all complete bids in the space. This is an
 * {@link ImmutableList} so it can contain all bids without pre-computing them.
 * 
 */
public class AllBidsList extends AbstractImmutableList<Bid> {

        private final List<String> issues;
        private final Outer<? extends Value> allValuePermutations;

        /**
         * This object contains s list containing all bids in the space. This is an
         * ImmutableList so it can contain all bids without pre-computing them.
         * 
         * @param domain the {@link Domain}
         * 
         */
        public AllBidsList(Domain domain) {
                if (domain == null)
                        throw new IllegalArgumentException("domain=null");
                issues = new ArrayList<>(domain.getIssues());

                List<ImmutableList<Value>> values = issues.stream()
                                .map(issue -> domain.getValues(issue))
                                .collect(Collectors.toList());

                allValuePermutations = new Outer<Value>(values);
        }

        @Override
        public Bid get(BigInteger index) {
                ImmutableList<? extends Value> nextValues = allValuePermutations
                                .get(index);

                Map<String, Value> issueValues = new HashMap<>();
                for (int n = 0; n < issues.size(); n++) {
                        issueValues.put(issues.get(n),
                                        nextValues.get(BigInteger.valueOf(n)));
                }
                return new Bid(issueValues);
        }

        @Override
        public BigInteger size() {
                return allValuePermutations.size();
        }

}