/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.pig.newplan.logical.rules;
import java.util.List;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.newplan.logical.expression.*;
import org.apache.pig.newplan.logical.relational.LogicalSchema;
import org.apache.pig.newplan.Operator;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.PlanVisitor;
import org.apache.pig.data.DataType;
/**
*
* A boolean expression with multiple children vs. the usual binary
* boolean expression.
*
*/
class DNFExpression extends LogicalExpression {
enum DNFExpressionType {
AND, OR
}
final DNFExpressionType type;
DNFExpression(String name, OperatorPlan plan, DNFExpressionType type) {
super(name, plan);
this.type = type;
}
@Override
public void accept(PlanVisitor v) throws FrontendException {
throw new FrontendException(
"DNF expression does not accept any visitor");
}
@Override
public boolean isEqual(Operator other) {
if (other != null && other instanceof DNFExpression) {
DNFExpression otherexp = (DNFExpression) other;
if (type != otherexp.type) return false;
try {
// this equality check is too strong: it does not allow for permutations;
// should be improved in the future
List<Operator> thisChildren = plan.getSuccessors(this), thatChildren = plan.getSuccessors(otherexp);
if (thisChildren == null && thatChildren == null) return true;
else if (thisChildren == null || thatChildren == null) return false;
else {
if (thisChildren.size() != thatChildren.size())
return false;
for (int i = 0; i < thisChildren.size(); i++) {
if (!thisChildren.get(i).isEqual(
thatChildren.get(i)))
return false;
}
}
}
catch (FrontendException e) {
throw new RuntimeException(e);
}
return true;
}
else {
return false;
}
}
@Override
public LogicalSchema.LogicalFieldSchema getFieldSchema()
throws FrontendException {
if (fieldSchema != null) return fieldSchema;
fieldSchema = new LogicalSchema.LogicalFieldSchema(null, null,
DataType.BOOLEAN);
fieldSchema.stampFieldSchema();
return fieldSchema;
}
@Override
public LogicalExpression deepCopy(LogicalExpressionPlan lgExpPlan) throws FrontendException {
throw new FrontendException("Deepcopy not expected");
}
}