/*
* Copyright 2015, The Querydsl Team (http://www.querydsl.com/team)
*
* 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.querydsl.collections;
import java.util.List;
import java.util.Map;
import com.querydsl.core.QueryMetadata;
import com.querydsl.core.types.Expression;
/**
* {@code QueryEngine} defines an interface for the evaluation of ColQuery queries
*
* @author tiwe
*
*/
public interface QueryEngine {
/**
* Evaluate the given query and return the count of matched rows
*
* @param metadata query metadata
* @param iterables source contents
* @return matching row count
*/
long count(QueryMetadata metadata, Map<Expression<?>, Iterable<?>> iterables);
/**
* Evaluate the given query and return the projection as a list
*
* @param metadata query metadata
* @param iterables source contents
* @return matching rows
*/
<T> List<T> list(QueryMetadata metadata, Map<Expression<?>, Iterable<?>> iterables,
Expression<T> projection);
/**
* Evaluate the given query return whether rows where matched
*
* @param metadata query metadata
* @param iterables source contents
* @return true, if at least one row was matched
*/
boolean exists(QueryMetadata metadata, Map<Expression<?>, Iterable<?>> iterables);
}