scale.clef.expr
Class ExpressionIfOp

java.lang.Object
  scale.common.Root
      scale.clef.Node
          scale.clef.expr.Expression
              scale.clef.expr.TernaryOp
                  scale.clef.expr.ExpressionIfOp

All Implemented Interfaces:

AnnotationInterface, DisplayNode

public class ExpressionIfOp
extends TernaryOp

This class is used to represents the C conditional operator.

$Id: ExpressionIfOp.java,v 1.31 2005-09-09 15:04:44 burrill Exp $

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

This class represents the C ?: operator. The result type is the type of the second expression (the types of the second and third expressions must be the same).

Constructor Summary

ExpressionIfOp(Type type, Expression test, Expression trueExpr, Expression falseExpr)

Method Summary

Literal	getConstantValue() Return the constant value of the expression.
boolean	hasTrueFalseResult() Return true if the result of the expression is either true (1) or false (0).
boolean	isSimpleOp() Return true if compilation of this expression will not result in the generation of a CFG node.
void	visit(Predicate p) Process a node by calling its associated routine.

Methods inherited from class scale.clef.expr.TernaryOp

containsDeclaration, equivalent, getChild, getDeclList, getExpr1, getExpr2, getExpr3, numChildren, setExpr1, setExpr2, setExpr3

Methods inherited from class scale.clef.expr.Expression

canonical, getCoreType, getDisplayColorHint, getDisplayLabel, getDisplayShapeHint, getPointedToCore, getType, setType, toStringSpecial

Methods inherited from class scale.clef.Node

getDecl, getSourceLineNumber, 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

ExpressionIfOp

public ExpressionIfOp(Type type,
                      Expression test,
                      Expression trueExpr,
                      Expression falseExpr)

Method Detail

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 TernaryOp

See Also:

Predicate

isSimpleOp

public boolean isSimpleOp()

Description copied from class: Expression

Return true if compilation of this expression will not result in the generation of a CFG node. For example, (a && b) may require a branch to represent and i++ requires a store.

Overrides:

isSimpleOp in class TernaryOp

hasTrueFalseResult

public boolean hasTrueFalseResult()

Return true if the result of the expression is either true (1) or false (0).

Overrides:

hasTrueFalseResult in class Expression

getConstantValue

public Literal getConstantValue()

Return the constant value of the expression.

Overrides:

getConstantValue in class Expression

See Also:

Lattice