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/*
 * Copyright (c) 2008-2018, Hazelcast, Inc. All Rights Reserved.
 *
 * Licensed 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 com.hazelcast.query.impl.predicates;

import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.BinaryInterface;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;
import com.hazelcast.query.IndexAwarePredicate;
import com.hazelcast.query.Predicate;
import com.hazelcast.query.VisitablePredicate;
import com.hazelcast.query.impl.AndResultSet;
import com.hazelcast.query.impl.Indexes;
import com.hazelcast.query.impl.OrResultSet;
import com.hazelcast.query.impl.QueryContext;
import com.hazelcast.query.impl.QueryableEntry;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;

import java.io.IOException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

import static com.hazelcast.internal.serialization.impl.FactoryIdHelper.PREDICATE_DS_FACTORY_ID;

/**
 * And Predicate
 */
@BinaryInterface
public final class AndPredicate
        implements IndexAwarePredicate, IdentifiedDataSerializable, VisitablePredicate, NegatablePredicate, CompoundPredicate {

    protected Predicate[] predicates;

    public AndPredicate() {
    }

    public AndPredicate(Predicate... predicates) {
        this.predicates = predicates;
    }

    @Override
    public Predicate accept(Visitor visitor, Indexes indexes) {
        Predicate[] result = VisitorUtils.acceptVisitor(predicates, visitor, indexes);
        if (result != predicates) {
            //inner predicates were modified by a visitor
            AndPredicate newPredicate = new AndPredicate(result);
            return visitor.visit(newPredicate, indexes);
        }
        return visitor.visit(this, indexes);
    }

    @Override
    public Set filter(QueryContext queryContext) {
        Set smallestResultSet = null;
        List> otherResultSets = null;
        List unindexedPredicates = null;

        for (Predicate predicate : predicates) {
            if (isIndexedPredicate(predicate, queryContext)) {
                Set currentResultSet = ((IndexAwarePredicate) predicate).filter(queryContext);
                if (smallestResultSet == null) {
                    smallestResultSet = currentResultSet;
                } else if (sizeOf(currentResultSet) < sizeOf(smallestResultSet)) {
                    otherResultSets = initOrGetListOf(otherResultSets);
                    otherResultSets.add(smallestResultSet);
                    smallestResultSet = currentResultSet;
                } else {
                    otherResultSets = initOrGetListOf(otherResultSets);
                    otherResultSets.add(currentResultSet);
                }
            } else {
                unindexedPredicates = initOrGetListOf(unindexedPredicates);
                unindexedPredicates.add(predicate);
            }
        }

        if (smallestResultSet == null) {
            return null;
        }
        return new AndResultSet(smallestResultSet, otherResultSets, unindexedPredicates);
    }

    private static boolean isIndexedPredicate(Predicate predicate, QueryContext queryContext) {
        return predicate instanceof IndexAwarePredicate && ((IndexAwarePredicate) predicate).isIndexed(queryContext);
    }

    private static  List initOrGetListOf(List list) {
        if (list == null) {
            list = new LinkedList();
        }
        return list;
    }

    private static int sizeOf(Set result) {
        // In case of AndResultSet and OrResultSet calling size() may be very expensive so quicker estimatedSize() is used
        if (result instanceof AndResultSet) {
            return ((AndResultSet) result).estimatedSize();
        } else if (result instanceof OrResultSet) {
            return ((OrResultSet) result).estimatedSize();
        }
        return result.size();
    }

    @Override
    public boolean isIndexed(QueryContext queryContext) {
        for (Predicate predicate : predicates) {
            if (predicate instanceof IndexAwarePredicate) {
                IndexAwarePredicate iap = (IndexAwarePredicate) predicate;
                if (iap.isIndexed(queryContext)) {
                    return true;
                }
            }
        }
        return false;
    }

    @Override
    public boolean apply(Map.Entry mapEntry) {
        for (Predicate predicate : predicates) {
            if (!predicate.apply(mapEntry)) {
                return false;
            }
        }
        return true;
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder();
        sb.append('(');
        int size = predicates.length;
        for (int i = 0; i < size; i++) {
            if (i > 0) {
                sb.append(" AND ");
            }
            sb.append(predicates[i]);
        }
        sb.append(')');
        return sb.toString();
    }

    @Override
    public void writeData(ObjectDataOutput out) throws IOException {
        out.writeInt(predicates.length);
        for (Predicate predicate : predicates) {
            out.writeObject(predicate);
        }
    }

    @Override
    public void readData(ObjectDataInput in) throws IOException {
        int size = in.readInt();
        predicates = new Predicate[size];
        for (int i = 0; i < size; i++) {
            predicates[i] = in.readObject();
        }
    }

    @Override
    public Predicate negate() {
        int size = predicates.length;
        Predicate[] inners = new Predicate[size];
        for (int i = 0; i < size; i++) {
            Predicate original = predicates[i];
            Predicate negated;
            if (original instanceof NegatablePredicate) {
                negated = ((NegatablePredicate) original).negate();
            } else {
                negated = new NotPredicate(original);
            }
            inners[i] = negated;
        }
        OrPredicate orPredicate = new OrPredicate(inners);
        return orPredicate;
    }

    @Override
    public int getFactoryId() {
        return PREDICATE_DS_FACTORY_ID;
    }

    @Override
    public int getId() {
        return PredicateDataSerializerHook.AND_PREDICATE;
    }

    /**
     * Visitable predicates are treated as effectively immutable, therefore callers should not make any changes to
     * the returned array.
     */
    @Override
    @SuppressFBWarnings("EI_EXPOSE_REP")
    public  Predicate[] getPredicates() {
        return predicates;
    }

    /**
     * Visitable predicates are treated as effectively immutable, therefore callers should not make any changes to
     * the array passed as argument after is has been set.
     *
     * @param predicates the array of sub-predicates for this {@code And} operator. It is not safe to make any changes to
     *                   this array after it has been set.
     */
    @Override
    @SuppressFBWarnings("EI_EXPOSE_REP")
    public  void setPredicates(Predicate[] predicates) {
        if (this.predicates == null) {
            this.predicates = predicates;
        } else {
            throw new IllegalStateException("Cannot reset predicates in an AndPredicate after they have been already set.");
        }
    }
}




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