ai.grakn.graql.internal.reasoner.query.QueryAnswers.java Source code

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Here is the source code for ai.grakn.graql.internal.reasoner.query.QueryAnswers.java

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/*
 * Grakn - A Distributed Semantic Database
 * Copyright (C) 2016  Grakn Labs Limited
 *
 * Grakn is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Grakn is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Grakn. If not, see <http://www.gnu.org/licenses/gpl.txt>.
 */

package ai.grakn.graql.internal.reasoner.query;

import ai.grakn.graql.Var;
import ai.grakn.graql.admin.Answer;
import ai.grakn.graql.admin.ReasonerQuery;
import ai.grakn.graql.admin.Unifier;
import ai.grakn.graql.internal.query.QueryAnswer;
import com.google.common.collect.Maps;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;

/**
 *
 * <p>
 * Wrapper class for a set of {@link Answer} objects providing higher level facilities.
 *
 * @author Kasper Piskorski
 *
 */
public class QueryAnswers implements Iterable<Answer> {

    private static final long serialVersionUID = -8092703897236995422L;

    private final HashSet<Answer> set = new HashSet<>();

    @Override
    public Iterator<Answer> iterator() {
        return set.iterator();
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == this)
            return true;
        if (obj == null || !(obj instanceof QueryAnswers))
            return false;
        QueryAnswers a2 = (QueryAnswers) obj;
        return set.equals(a2.set);
    }

    @Override
    public int hashCode() {
        return set.hashCode();
    }

    public Stream<Answer> stream() {
        return set.stream();
    }

    public QueryAnswers() {
    }

    public QueryAnswers(Answer ans) {
        set.add(ans);
    }

    public QueryAnswers(Collection<Answer> ans) {
        ans.forEach(set::add);
    }

    public QueryAnswers(QueryAnswers ans) {
        ans.forEach(set::add);
    }

    public boolean add(Answer a) {
        return set.add(a);
    }

    public boolean addAll(QueryAnswers ans) {
        return set.addAll(ans.set);
    }

    public boolean remove(Answer a) {
        return set.remove(a);
    }

    public boolean removeAll(QueryAnswers ans) {
        return set.removeAll(ans.set);
    }

    public boolean containsAll(QueryAnswers ans) {
        return set.containsAll(ans.set);
    }

    public int size() {
        return set.size();
    }

    public boolean isEmpty() {
        return set.isEmpty();
    }

    /**
     * filter answers by constraining the variable set to the provided one
     * @param vars set of variable names
     * @return filtered answers
     */
    public QueryAnswers filterVars(Set<Var> vars) {
        return new QueryAnswers(this.stream().map(result -> Maps.filterKeys(result.map(), vars::contains))
                .map(QueryAnswer::new).collect(Collectors.toSet()));
    }

    /**
     * unify the answers by applying unifiers to variable set
     * @param unifier map of [key: from/value: to] unifiers
     * @return unified query answers
     */
    public QueryAnswers unify(Unifier unifier) {
        if (unifier.isEmpty())
            return new QueryAnswers(this);
        QueryAnswers unifiedAnswers = new QueryAnswers();
        this.stream().map(a -> a.unify(unifier)).filter(a -> !a.isEmpty()).forEach(unifiedAnswers::add);
        return unifiedAnswers;
    }

    /**
     * unify answers of childQuery with parentQuery
     * @param parentQuery parent atomic query containing target variables
     * @return unified answers
     */
    public static <T extends ReasonerQuery> QueryAnswers getUnifiedAnswers(T parentQuery, T childQuery,
            QueryAnswers answers) {
        if (parentQuery == childQuery)
            return new QueryAnswers(answers);
        return answers.unify(childQuery.getUnifier(parentQuery));
    }
}