/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2009 by Red Hat Inc and/or its affiliates or by
* third-party contributors as indicated by either @author tags or express
* copyright attribution statements applied by the authors. All
* third-party contributions are distributed under license by Red Hat Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.ejb.criteria.expression.function;
import java.io.Serializable;
import java.util.List;
import javax.persistence.criteria.Expression;
import javax.persistence.criteria.Root;
import org.hibernate.ejb.criteria.CriteriaBuilderImpl;
import org.hibernate.ejb.criteria.CriteriaQueryCompiler;
import org.hibernate.ejb.criteria.expression.LiteralExpression;
/**
* Models SQL aggregation functions (<tt>MIN</tt>, <tt>MAX</tt>, <tt>COUNT</tt>, etc).
*
* @author Steve Ebersole
*/
public class AggregationFunction<T>
extends ParameterizedFunctionExpression<T>
implements Serializable {
/**
* Constructs an aggregation function with a single literal argument.
*
* @param criteriaBuilder The query builder instance.
* @param returnType The function return type.
* @param functionName The name of the function.
* @param argument The literal argument
*/
@SuppressWarnings({ "unchecked" })
public AggregationFunction(
CriteriaBuilderImpl criteriaBuilder,
Class<T> returnType,
String functionName,
Object argument) {
this( criteriaBuilder, returnType, functionName, new LiteralExpression( criteriaBuilder, argument ) );
}
/**
* Constructs an aggregation function with a single literal argument.
*
* @param criteriaBuilder The query builder instance.
* @param returnType The function return type.
* @param functionName The name of the function.
* @param argument The argument
*/
public AggregationFunction(
CriteriaBuilderImpl criteriaBuilder,
Class<T> returnType,
String functionName,
Expression<?> argument) {
super( criteriaBuilder, returnType, functionName, argument );
}
@Override
public boolean isAggregation() {
return true;
}
/**
* Implementation of a <tt>COUNT</tt> function providing convenience in construction.
* <p/>
* Parameterized as {@link Long} because thats what JPA states
* that the return from <tt>COUNT</tt> should be.
*/
public static class COUNT extends AggregationFunction<Long> {
public static final String NAME = "count";
private final boolean distinct;
public COUNT(CriteriaBuilderImpl criteriaBuilder, Expression<?> expression, boolean distinct) {
super( criteriaBuilder, Long.class, NAME , expression );
this.distinct = distinct;
}
@Override
protected void renderArguments( StringBuilder buffer,
CriteriaQueryCompiler.RenderingContext renderingContext ) {
if (isDistinct()) buffer.append("distinct ");
else {
// If function specifies a single non-distinct entity with ID, its alias would normally be rendered, which ends up
// converting to the column(s) associated with the entity's ID in the rendered SQL. However, some DBs don't support
// the multiple columns that would end up here for entities with composite IDs. So, since we modify the query to
// instead specify star since that's functionally equivalent and supported by all DBs.
List<Expression<?>> argExprs = getArgumentExpressions();
if (argExprs.size() == 1) {
Expression argExpr = argExprs.get(0);
if (argExpr instanceof Root<?>) {
Root<?> root = (Root<?>)argExpr;
if (root.getModel().getIdType() != null) {
buffer.append('*');
return;
}
}
}
}
super.renderArguments(buffer, renderingContext);
}
public boolean isDistinct() {
return distinct;
}
}
/**
* Implementation of a <tt>AVG</tt> function providing convenience in construction.
* <p/>
* Parameterized as {@link Double} because thats what JPA states that the return from <tt>AVG</tt> should be.
*/
public static class AVG extends AggregationFunction<Double> {
public static final String NAME = "avg";
public AVG(CriteriaBuilderImpl criteriaBuilder, Expression<? extends Number> expression) {
super( criteriaBuilder, Double.class, NAME, expression );
}
}
/**
* Implementation of a <tt>SUM</tt> function providing convenience in construction.
* <p/>
* Parameterized as {@link Number N extends Number} because thats what JPA states
* that the return from <tt>SUM</tt> should be.
*/
public static class SUM<N extends Number> extends AggregationFunction<N> {
public static final String NAME = "sum";
@SuppressWarnings({ "unchecked" })
public SUM(CriteriaBuilderImpl criteriaBuilder, Expression<N> expression) {
super( criteriaBuilder, (Class<N>)expression.getJavaType(), NAME , expression);
// force the use of a ValueHandler
resetJavaType( expression.getJavaType() );
}
public SUM(CriteriaBuilderImpl criteriaBuilder, Expression<? extends Number> expression, Class<N> returnType) {
super( criteriaBuilder, returnType, NAME , expression);
// force the use of a ValueHandler
resetJavaType( returnType );
}
}
/**
* Implementation of a <tt>MIN</tt> function providing convenience in construction.
* <p/>
* Parameterized as {@link Number N extends Number} because thats what JPA states
* that the return from <tt>MIN</tt> should be.
*/
public static class MIN<N extends Number> extends AggregationFunction<N> {
public static final String NAME = "min";
@SuppressWarnings({ "unchecked" })
public MIN(CriteriaBuilderImpl criteriaBuilder, Expression<N> expression) {
super( criteriaBuilder, ( Class<N> ) expression.getJavaType(), NAME , expression);
}
}
/**
* Implementation of a <tt>MAX</tt> function providing convenience in construction.
* <p/>
* Parameterized as {@link Number N extends Number} because thats what JPA states
* that the return from <tt>MAX</tt> should be.
*/
public static class MAX<N extends Number> extends AggregationFunction<N> {
public static final String NAME = "max";
@SuppressWarnings({ "unchecked" })
public MAX(CriteriaBuilderImpl criteriaBuilder, Expression<N> expression) {
super( criteriaBuilder, ( Class<N> ) expression.getJavaType(), NAME , expression);
}
}
/**
* Models the <tt>MIN</tt> function in terms of non-numeric expressions.
*
* @see MIN
*/
public static class LEAST<X extends Comparable<X>> extends AggregationFunction<X> {
public static final String NAME = "min";
@SuppressWarnings({ "unchecked" })
public LEAST(CriteriaBuilderImpl criteriaBuilder, Expression<X> expression) {
super( criteriaBuilder, ( Class<X> ) expression.getJavaType(), NAME , expression);
}
}
/**
* Models the <tt>MAX</tt> function in terms of non-numeric expressions.
*
* @see MAX
*/
public static class GREATEST<X extends Comparable<X>> extends AggregationFunction<X> {
public static final String NAME = "max";
@SuppressWarnings({ "unchecked" })
public GREATEST(CriteriaBuilderImpl criteriaBuilder, Expression<X> expression) {
super( criteriaBuilder, ( Class<X> ) expression.getJavaType(), NAME , expression);
}
}
}