/*
* 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.gen;
import com.facebook.presto.spi.PrestoException;
import com.facebook.presto.spi.StandardErrorCode;
import com.facebook.presto.sql.relational.CallExpression;
import com.facebook.presto.sql.relational.ConstantExpression;
import com.facebook.presto.sql.relational.InputReferenceExpression;
import com.facebook.presto.sql.relational.LambdaDefinitionExpression;
import com.facebook.presto.sql.relational.RowExpression;
import com.facebook.presto.sql.relational.RowExpressionVisitor;
import com.facebook.presto.sql.relational.VariableReferenceExpression;
import com.google.common.collect.ImmutableList;
import java.util.List;
import static com.facebook.presto.sql.relational.Signatures.TRY;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.Iterables.getOnlyElement;
public class LambdaAndTryExpressionExtractor
{
private LambdaAndTryExpressionExtractor()
{
}
public static List<RowExpression> extractLambdaAndTryExpressions(RowExpression expression)
{
Visitor visitor = new Visitor();
expression.accept(visitor, new Context(false));
return visitor.getLambdaAndTryExpressionsPostOrder();
}
private static class Visitor
implements RowExpressionVisitor<Context, Void>
{
private final ImmutableList.Builder<RowExpression> lambdaAndTryExpressions = ImmutableList.builder();
@Override
public Void visitInputReference(InputReferenceExpression node, Context context)
{
// TODO: change such that CallExpressions only capture the inputs they actually depend on
return null;
}
@Override
public Void visitCall(CallExpression call, Context context)
{
boolean isTry = call.getSignature().getName().equals(TRY);
if (isTry) {
checkState(call.getArguments().size() == 1, "try call expressions must have a single argument");
checkState(getOnlyElement(call.getArguments()) instanceof CallExpression, "try call expression argument must be a call expression");
if (context.isInLambda()) {
throw new PrestoException(StandardErrorCode.NOT_SUPPORTED, "Try expression inside lambda expression is not support yet");
}
}
for (RowExpression rowExpression : call.getArguments()) {
rowExpression.accept(this, context);
}
if (isTry) {
lambdaAndTryExpressions.add(getOnlyElement(call.getArguments()));
}
return null;
}
@Override
public Void visitConstant(ConstantExpression literal, Context context)
{
return null;
}
@Override
public Void visitLambda(LambdaDefinitionExpression lambda, Context context)
{
lambda.getBody().accept(this, new Context(true));
lambdaAndTryExpressions.add(lambda);
return null;
}
@Override
public Void visitVariableReference(VariableReferenceExpression reference, Context context)
{
return null;
}
private List<RowExpression> getLambdaAndTryExpressionsPostOrder()
{
return lambdaAndTryExpressions.build();
}
}
private static class Context
{
private final boolean inLambda;
public Context(boolean inLambda)
{
this.inLambda = inLambda;
}
public boolean isInLambda()
{
return inLambda;
}
}
}