scale.clef.expr
Class NilOp

java.lang.Object
  scale.common.Root
      scale.clef.Node
          scale.clef.expr.Expression
              scale.clef.expr.Literal
                  scale.clef.expr.NilOp

All Implemented Interfaces:

AnnotationInterface, DisplayNode

public class NilOp
extends Literal

A class which represents the nil pointer value.

$Id: NilOp.java,v 1.29 2005-02-07 21:27:59 burrill Exp $

Copyright 2005 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

Constructor Summary

NilOp()

NilOp(Type type)

Method Summary

boolean	equivalent(java.lang.Object exp) Return true if the two expressions are equivalent.
Literal	getConstantValue() Return the constant value of the expression.
java.lang.String	getGenericValue() Get the string version of the literal using C syntax.
void	visit(Predicate p) Process a node by calling its associated routine.

Methods inherited from class scale.clef.expr.Literal

executionCostEstimate, findCoefficient, formatRealValue, getCount, getDeclList, getDisplayLabel, getElement, isOne, isZero, linearity

Methods inherited from class scale.clef.expr.Expression

canonical, containsDeclaration, getCoreType, getDisplayColorHint, getDisplayShapeHint, getPointedToCore, getType, hasTrueFalseResult, isSimpleOp, setType, toStringSpecial

Methods inherited from class scale.clef.Node

getChild, getDecl, getSourceLineNumber, numChildren, setAnnotationLevel, setReportLevel, setSourceLineNumber, toString, toString, toStringChildren

Methods inherited from class scale.common.Root

addAnnotation, allAnnotations, allMatchingAnnotations, getAnnotation, getDisplayName, getDisplayString, getNodeCount, getNodeID, hasAnnotation, hasEqualAnnotation, hashCode, removeAnnotation, removeAnnotations, toStringAnnotations, toStringClass, trace, trace, trace

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

NilOp

public NilOp(Type type)

NilOp

public NilOp()

Method Detail

equivalent

public boolean equivalent(java.lang.Object exp)

Return true if the two expressions are equivalent.

Overrides:

equivalent in class Expression

visit

public void visit(Predicate p)

Description copied from class: Node

Process a node by calling its associated routine. See the "visitor" design pattern in Design Patterns: Elements of Reusable Object-Oriented Software by E. Gamma, et al, Addison Wesley, ISBN 0-201-63361-2.

Each class has a visit(Predicate p) method. For example, in class ABC:

   public void visit(Predicate p)
   {
     p.visitABC(this);
   }
 

and the class that implements Predicate has a method

   public void visitABC(Node n)
   {
     ABC a = (ABC) n;
     ...
   }
 

Thus, the class that implements Predicate can call

   n.visit(this);
 

where n is a Node sub-class without determining which specific sub-class n is. The visit pattern basically avoids implementing a large switch statement or defining different methods in each class for some purpose.

Overrides:

visit in class Literal

See Also:

Predicate

getGenericValue

public java.lang.String getGenericValue()

Description copied from class: Literal

Get the string version of the literal using C syntax. For another language, use getValue which returns an object that can then be displayed using logic specific to the target language.

Overrides:

getGenericValue in class Literal

Returns:

a String representing the literal value and uses C syntax

getConstantValue

public Literal getConstantValue()

Return the constant value of the expression.

Overrides:

getConstantValue in class Literal

See Also:

Lattice