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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you 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.org.apache.calcite.linq4j;

import com.hazelcast.org.apache.calcite.linq4j.tree.Expression;

import java.lang.reflect.Type;

/**
 * Defines methods to create and execute queries that are described by a
 * {@link Queryable} object.
 *
 * 

Analogous to LINQ's System.Linq.QueryProvider.

*/ public interface QueryProvider { /** * Constructs a {@link Queryable} object that can evaluate the query * represented by a specified expression tree. * *

NOTE: The {@link com.hazelcast.org.apache.calcite.linq4j.Queryable#getExpression()} * property of the returned {@link Queryable} object is equal to * {@code expression}.

* * @param expression Expression * @param rowType Row type * @param Row type * * @return Queryable */ Queryable createQuery(Expression expression, Class rowType); /** * Constructs a {@link Queryable} object that can evaluate the query * represented by a specified expression tree. The row type may contain * generic information. * * @param expression Expression * @param rowType Row type * @param Row type * * @return Queryable */ Queryable createQuery(Expression expression, Type rowType); /** * Executes the query represented by a specified expression tree. * *

This method executes queries that return a single value * (instead of an enumerable sequence of values). Expression trees that * represent queries that return enumerable results are executed when the * {@link Queryable} object that contains the expression tree is * enumerated.

* *

The Queryable standard query operator methods that return singleton * results call {@code execute}. They pass it a * {@link com.hazelcast.org.apache.calcite.linq4j.tree.MethodCallExpression} * that represents a linq4j query. */ T execute(Expression expression, Class type); /** * Executes the query represented by a specified expression tree. * The row type may contain type parameters. */ T execute(Expression expression, Type type); /** * Executes a queryable, and returns an enumerator over the * rows that it yields. * * @param queryable Queryable * * @return Enumerator over rows */ Enumerator executeQuery(Queryable queryable); }





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