io.trino.sql.planner.iterative.rule.RemoveDuplicateConditions Maven / Gradle / Ivy
/*
* 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 io.trino.sql.planner.iterative.rule;
import io.trino.metadata.Metadata;
import io.trino.sql.tree.Expression;
import io.trino.sql.tree.ExpressionTreeRewriter;
import io.trino.sql.tree.LogicalExpression;
import static io.trino.sql.ExpressionUtils.combinePredicates;
import static io.trino.sql.ExpressionUtils.extractPredicates;
/**
* Flattens and removes duplicate conjuncts or disjuncts. E.g.,
*
* a = 1 AND a = 1
*
* rewrites to:
*
* a = 1
*/
public class RemoveDuplicateConditions
extends ExpressionRewriteRuleSet
{
public RemoveDuplicateConditions(Metadata metadata)
{
super(createRewrite(metadata));
}
private static ExpressionRewriter createRewrite(Metadata metadata)
{
return (expression, context) -> ExpressionTreeRewriter.rewriteWith(new Visitor(metadata), expression);
}
private static class Visitor
extends io.trino.sql.tree.ExpressionRewriter
{
private final Metadata metadata;
public Visitor(Metadata metadata)
{
this.metadata = metadata;
}
@Override
public Expression rewriteLogicalExpression(LogicalExpression node, Void context, ExpressionTreeRewriter treeRewriter)
{
return combinePredicates(metadata, node.getOperator(), extractPredicates(node));
}
}
}