org.apache.pig.experimental.logical.expression
Class ConstantExpression

java.lang.Object
  extended by org.apache.pig.experimental.plan.Operator
      extended by org.apache.pig.experimental.logical.expression.LogicalExpression
          extended by org.apache.pig.experimental.logical.expression.ColumnExpression
              extended by org.apache.pig.experimental.logical.expression.ConstantExpression

public class ConstantExpression
extends ColumnExpression

A constant


Field Summary
 
Fields inherited from class org.apache.pig.experimental.logical.expression.LogicalExpression
type, uid
 
Fields inherited from class org.apache.pig.experimental.plan.Operator
annotations, hashPrime, name, plan
 
Constructor Summary
ConstantExpression(OperatorPlan plan, byte type, Object val)
          Adds expression to the plan
 
Method Summary
 void accept(PlanVisitor v)
          Accept a visitor at this node in the graph.
 Object getValue()
          Get the value of this constant.
 boolean isEqual(Operator other)
          This is like a shallow equals comparison.
 
Methods inherited from class org.apache.pig.experimental.logical.expression.LogicalExpression
getNextUid, getType, getUid, neverUseForRealSetUid, resetNextUid, setUid, toString
 
Methods inherited from class org.apache.pig.experimental.plan.Operator
annotate, getAnnotation, getName, getPlan, removeAnnotation
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

ConstantExpression

public ConstantExpression(OperatorPlan plan,
                          byte type,
                          Object val)
Adds expression to the plan

Parameters:
plan - LogicalExpressionPlan this constant is a part of.
type - type of the constant. This could be determined dynamically, but it would require a long chain of instanceofs, and the parser will already know the type, so there's no reason to take the performance hit.
val - Value of this constant.
Method Detail

accept

public void accept(PlanVisitor v)
            throws IOException
Description copied from class: Operator
Accept a visitor at this node in the graph.

Specified by:
accept in class Operator
Parameters:
v - Visitor to accept.
Throws:
IOException

getValue

public Object getValue()
Get the value of this constant.

Returns:
value of the constant

isEqual

public boolean isEqual(Operator other)
Description copied from class: Operator
This is like a shallow equals comparison. It returns true if two operators have equivalent properties even if they are different objects. Here properties mean equivalent plan and equivalent name.

Specified by:
isEqual in class Operator
Returns:
true if two object have equivalent properties, else false


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