com.blazebit.persistence.impl.transform.ClauseAndJoinAwareResultVisitor Maven / Gradle / Ivy
/*
* Copyright 2014 - 2020 Blazebit.
*
* 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.blazebit.persistence.impl.transform;
import com.blazebit.persistence.impl.ClauseType;
import com.blazebit.persistence.parser.expression.Expression;
import com.blazebit.persistence.parser.expression.InplaceModificationResultVisitorAdapter;
import com.blazebit.persistence.parser.predicate.EqPredicate;
import com.blazebit.persistence.parser.predicate.InPredicate;
import com.blazebit.persistence.parser.predicate.IsEmptyPredicate;
import com.blazebit.persistence.parser.predicate.IsNullPredicate;
import com.blazebit.persistence.parser.predicate.MemberOfPredicate;
/**
* This visitor keeps track of whether joins are required which might change depending on the predicates.
* It is also keeps the clause for which it is executed.
*
* @author Christian Beikov
* @author Moritz Becker
* @since 1.2.0
*/
public class ClauseAndJoinAwareResultVisitor extends InplaceModificationResultVisitorAdapter {
protected ClauseType fromClause;
// By default we require joins
protected boolean joinRequired = true;
public Expression visit(ClauseType clauseType, Expression expression) {
this.fromClause = clauseType;
try {
return expression.accept(this);
} finally {
this.fromClause = null;
}
}
@Override
public Expression visit(EqPredicate predicate) {
boolean original = joinRequired;
joinRequired = false;
super.visit(predicate);
joinRequired = original;
return predicate;
}
@Override
public Expression visit(InPredicate predicate) {
boolean original = joinRequired;
joinRequired = false;
super.visit(predicate);
joinRequired = original;
return predicate;
}
@Override
public Expression visit(MemberOfPredicate predicate) {
boolean original = joinRequired;
joinRequired = false;
super.visit(predicate);
joinRequired = original;
return predicate;
}
@Override
public Expression visit(IsEmptyPredicate predicate) {
boolean original = joinRequired;
joinRequired = false;
super.visit(predicate);
joinRequired = original;
return predicate;
}
@Override
public Expression visit(IsNullPredicate predicate) {
boolean original = joinRequired;
joinRequired = false;
super.visit(predicate);
joinRequired = original;
return predicate;
}
}