/*
* 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.planner;
import com.facebook.presto.sql.tree.DefaultTraversalVisitor;
import com.facebook.presto.sql.tree.Expression;
import com.facebook.presto.sql.tree.Node;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import javax.annotation.Nullable;
import java.util.List;
import java.util.Set;
/**
* Extracts and returns the set of all expression subtrees within an Expression, including Expression itself
*/
public final class SubExpressionExtractor
{
private SubExpressionExtractor() {}
public static List<Expression> extractAll(Iterable<Expression> expressions)
{
ImmutableList.Builder<Expression> builder = ImmutableList.builder();
for (Expression expression : expressions) {
extract(builder, expression);
}
return builder.build();
}
public static List<Expression> extractAll(Expression expression)
{
ImmutableList.Builder<Expression> builder = ImmutableList.builder();
extract(builder, expression);
return builder.build();
}
public static Set<Expression> extract(Expression expression)
{
final ImmutableSet.Builder<Expression> builder = ImmutableSet.builder();
extract(builder, expression);
return builder.build();
}
private static void extract(final ImmutableCollection.Builder<Expression> builder, Expression expression)
{
new DefaultTraversalVisitor<Void, Void>()
{
@Override
public Void process(Node node, @Nullable Void context)
{
Expression expression = (Expression) node;
builder.add(expression);
return super.process(node, context);
}
}.process(expression, null);
}
}