com.mysema.query.group.GroupExpression Maven / Gradle / Ivy
/*
* 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.mysema.query.group;
import com.mysema.query.types.Expression;
/**
* Defines the way results of a given expression are grouped. GroupExpressions are also used
* to access values of a given GroupExpression within a Group.
* GroupExpressions are stateless wrappers for Expressions that know how to
* collect row values into a group.
*
* @author sasa
* @author tiwe
*
* @param
*/
public interface GroupExpression extends Expression {
/**
* @return Expression wrapped by this group definition
*/
Expression getExpression();
/**
* @return a new GroupCollector to collect values belonging to this group.
*/
GroupCollector createGroupCollector();
}