/*
* 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.relational;
import com.facebook.presto.metadata.FunctionRegistry;
import com.facebook.presto.metadata.Signature;
import static java.util.Objects.requireNonNull;
public class DeterminismEvaluator
{
final FunctionRegistry registry;
public DeterminismEvaluator(FunctionRegistry registry)
{
this.registry = requireNonNull(registry, "registry is null");
}
public boolean isDeterministic(RowExpression expression)
{
return expression.accept(new Visitor(registry), null);
}
private static class Visitor
implements RowExpressionVisitor<Void, Boolean>
{
private final FunctionRegistry registry;
public Visitor(FunctionRegistry registry)
{
this.registry = registry;
}
@Override
public Boolean visitInputReference(InputReferenceExpression reference, Void context)
{
return true;
}
@Override
public Boolean visitConstant(ConstantExpression literal, Void context)
{
return true;
}
@Override
public Boolean visitCall(CallExpression call, Void context)
{
Signature signature = call.getSignature();
if (registry.isRegistered(signature) && !registry.getScalarFunctionImplementation(signature).isDeterministic()) {
return false;
}
return call.getArguments().stream()
.allMatch(expression -> expression.accept(this, context));
}
@Override
public Boolean visitLambda(LambdaDefinitionExpression lambda, Void context)
{
return lambda.getBody().accept(this, context);
}
@Override
public Boolean visitVariableReference(VariableReferenceExpression reference, Void context)
{
return true;
}
}
}