io.trino.sql.ir.optimizer.rule.FlattenLogical 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.ir.optimizer.rule;
import com.google.common.collect.ImmutableList;
import io.trino.Session;
import io.trino.sql.ir.Expression;
import io.trino.sql.ir.Logical;
import io.trino.sql.ir.optimizer.IrOptimizerRule;
import io.trino.sql.planner.Symbol;
import java.util.List;
import java.util.Map;
import java.util.Optional;
/**
* Flatten nested logical terms. E.g,
*
* - {@code And(And(a, b), And(c, d), ...) -> And(a, b, c, d, ...)}
*
- {@code Or(Or(a, b), Or(c, d), ...) -> Orr(a, b, c, d, ...)}
*
*/
public class FlattenLogical
implements IrOptimizerRule
{
@Override
public Optional apply(Expression expression, Session session, Map bindings)
{
if (!(expression instanceof Logical logical)) {
return Optional.empty();
}
if (logical.terms().stream().noneMatch(e -> e instanceof Logical inner && inner.operator() == logical.operator())) {
return Optional.empty();
}
ImmutableList.Builder terms = ImmutableList.builder();
flatten(logical.operator(), logical.terms(), terms);
return Optional.of(new Logical(logical.operator(), terms.build()));
}
private void flatten(Logical.Operator operator, List terms, ImmutableList.Builder accumulator)
{
for (Expression term : terms) {
if (term instanceof Logical logical && logical.operator() == operator) {
flatten(operator, logical.terms(), accumulator);
}
else {
accumulator.add(term);
}
}
}
}