/*
* 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.facebook.presto.sql.analyzer;
import com.facebook.presto.sql.tree.DefaultExpressionTraversalVisitor;
import com.facebook.presto.sql.tree.Expression;
import com.facebook.presto.sql.tree.Identifier;
import com.facebook.presto.sql.tree.Node;
import com.google.common.collect.ImmutableList;
import java.util.List;
import static java.util.Objects.requireNonNull;
/**
* Extract expressions that are references to a lambda argument.
*/
public class LambdaReferenceExtractor
{
private LambdaReferenceExtractor() {}
public static boolean hasReferencesToLambdaArgument(Node node, Analysis analysis)
{
return !getReferencesToLambdaArgument(node, analysis).isEmpty();
}
public static List<Expression> getReferencesToLambdaArgument(Node node, Analysis analysis)
{
ImmutableList.Builder<Expression> builder = ImmutableList.builder();
new Visitor(analysis).process(node, builder);
return builder.build();
}
private static class Visitor
extends DefaultExpressionTraversalVisitor<Void, ImmutableList.Builder<Expression>>
{
private final Analysis analysis;
private Visitor(Analysis analysis)
{
this.analysis = requireNonNull(analysis, "analysis is null");
}
@Override
protected Void visitIdentifier(Identifier node, ImmutableList.Builder<Expression> context)
{
if (analysis.getLambdaArgumentReferences().containsKey(node)) {
context.add(node);
}
return null;
}
}
}