/*
* 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.Expression;
import com.facebook.presto.sql.tree.ExpressionRewriter;
import com.facebook.presto.sql.tree.ExpressionTreeRewriter;
import com.facebook.presto.sql.tree.LambdaArgumentDeclaration;
import com.facebook.presto.sql.tree.LambdaExpression;
import com.facebook.presto.sql.tree.SymbolReference;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkState;
public class ExpressionSymbolInliner
{
private final Function<Symbol, Expression> mapping;
@Deprecated
public ExpressionSymbolInliner(Map<Symbol, ? extends Expression> mappings)
{
this.mapping = mappings::get;
}
public ExpressionSymbolInliner(Function<Symbol, Expression> mapping)
{
this.mapping = mapping;
}
public Expression rewrite(Expression expression)
{
return ExpressionTreeRewriter.rewriteWith(new Visitor(), expression);
}
private class Visitor
extends ExpressionRewriter<Void>
{
private final Set<String> excludedNames = new HashSet<>();
@Override
public Expression rewriteSymbolReference(SymbolReference node, Void context, ExpressionTreeRewriter<Void> treeRewriter)
{
if (excludedNames.contains(node.getName())) {
return node;
}
Expression expression = mapping.apply(Symbol.from(node));
checkState(expression != null, "Cannot resolve symbol %s", node.getName());
return expression;
}
@Override
public Expression rewriteLambdaExpression(LambdaExpression node, Void context, ExpressionTreeRewriter<Void> treeRewriter)
{
for (LambdaArgumentDeclaration argument : node.getArguments()) {
String argumentName = argument.getName();
// Symbol names are unique. As a result, a symbol should never be excluded multiple times.
checkArgument(!excludedNames.contains(argumentName));
excludedNames.add(argumentName);
}
Expression result = treeRewriter.defaultRewrite(node, context);
for (LambdaArgumentDeclaration argument : node.getArguments()) {
excludedNames.remove(argument.getName());
}
return result;
}
}
}