/*
* 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.expression;
import org.apache.pig.PigException;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.logicalLayer.FrontendException;
import org.apache.pig.newplan.Operator;
import org.apache.pig.newplan.OperatorPlan;
import org.apache.pig.newplan.PlanVisitor;
import org.apache.pig.newplan.logical.Util;
import org.apache.pig.newplan.logical.relational.LogicalSchema.LogicalFieldSchema;
import org.apache.pig.parser.SourceLocation;
/**
* A constant
*
*/
public class ConstantExpression extends ColumnExpression {
// Stupid Java needs a union
Object val;
// Remember data type when the value is null
byte type = DataType.NULL;
/**
* Adds expression to the plan
* @param plan LogicalExpressionPlan this constant is a part of.
* @param val Value of this constant.
*/
public ConstantExpression(OperatorPlan plan, Object val){
super("Constant", plan);
this.val = val;
plan.add(this);
}
/**
* @link org.apache.pig.newplan.Operator#accept(org.apache.pig.newplan.PlanVisitor)
*/
@Override
public void accept(PlanVisitor v) throws FrontendException {
if (!(v instanceof LogicalExpressionVisitor)) {
throw new FrontendException("Expected LogicalExpressionVisitor", 2222);
}
((LogicalExpressionVisitor)v).visit(this);
}
/**
* Get the value of this constant.
* @return value of the constant
*/
public Object getValue() {
return val;
}
public void setValue(Object val) {
this.val = val;
}
@Override
public boolean isEqual(Operator other) throws FrontendException {
if (other != null && other instanceof ConstantExpression) {
ConstantExpression co = (ConstantExpression)other;
return co.getFieldSchema().isEqual(getFieldSchema()) && ( ( co.val == null && val == null )
|| ( co != null && co.val.equals(val) ) );
} else {
return false;
}
}
@Override
public LogicalFieldSchema getFieldSchema() throws FrontendException {
if (fieldSchema!=null)
return fieldSchema;
try {
fieldSchema = Util.translateFieldSchema(DataType.determineFieldSchema(val));
}catch (Exception e) {
throw new FrontendException(
"Error determining field schema from object in constant expression",
1125,
PigException.INPUT,
e
);
}
uidOnlyFieldSchema = fieldSchema.mergeUid(uidOnlyFieldSchema);
if (type != DataType.NULL && fieldSchema.type == DataType.BYTEARRAY && val == null) {
fieldSchema.type = type;
}
return fieldSchema;
}
@Override
public LogicalExpression deepCopy(LogicalExpressionPlan lgExpPlan) throws FrontendException{
ConstantExpression copy = new ConstantExpression(lgExpPlan, this.getValue());
copy.type = this.type;
copy.setLocation( new SourceLocation( location ) );
return copy;
}
public void inheritSchema(LogicalExpression expr) throws FrontendException {
fieldSchema = expr.getFieldSchema();
uidOnlyFieldSchema = fieldSchema.mergeUid(uidOnlyFieldSchema);
if (fieldSchema.type != DataType.NULL) {
type = fieldSchema.type;
}
}
}