com.mysema.query.collections.QueryEngine Maven / Gradle / Ivy

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/*
 * Copyright (c) 2010 Mysema Ltd.
 * All rights reserved.
 *
 */
package com.mysema.query.collections;

import java.util.List;
import java.util.Map;

import com.mysema.query.QueryMetadata;
import com.mysema.query.types.Expression;

/**
 * QueryEngine defines an interface for the evaluation of ColQuery queries
 *
 * @author tiwe
 *
 */
public interface QueryEngine {

    /**
     * Default instance
     */
    QueryEngine DEFAULT = new DefaultQueryEngine(new DefaultEvaluatorFactory(ColQueryTemplates.DEFAULT));

    /**
     * Evaluate the given query and return the count of matched rows
     *
     * @param metadata
     * @param iterables
     * @return
     */
    long count(QueryMetadata metadata, Map, Iterable> iterables);

    /**
     * Evaluate the given query and return the projection as a list
     *
     * @param metadata
     * @param iterables
     * @return
     */
     List list(QueryMetadata metadata, Map, Iterable> iterables, Expression projection);

    /**
     * @param metadata
     * @param iterables
     * @return
     */
    boolean exists(QueryMetadata metadata, Map, Iterable> iterables);

}