scale.clef.expr
Class CompoundAssignmentOp

java.lang.Object
  scale.common.Root
      scale.clef.Node
          scale.clef.expr.Expression
              scale.clef.expr.DyadicOp
                  scale.clef.expr.AssignmentOp
                      scale.clef.expr.CompoundAssignmentOp

All Implemented Interfaces:

AnnotationInterface, DisplayNode

Direct Known Subclasses:

AdditionAssignmentOp, BitAndAssignmentOp, BitOrAssignmentOp, BitShiftAssignmentOp, BitXorAssignmentOp, DivisionAssignmentOp, MultiplicationAssignmentOp, RemainderAssignmentOp, SubtractionAssignmentOp

public abstract class CompoundAssignmentOp
extends AssignmentOp

This is the base class for all compound assignments such as +=.

$Id: CompoundAssignmentOp.java,v 1.23 2006-12-18 21:36:49 burrill Exp $

Copyright 2006 by the Scale Compiler Group,
Department of Computer Science
University of Massachusetts,
Amherst MA. 01003, USA
All Rights Reserved.

Note that x += y is not equivalent to x = x + y when x is a an expression with side effects.

Constructor Summary

CompoundAssignmentOp(Type type, Type calcType, Expression lhs, Expression ra)

Method Summary

Type	getCalcType() Return the type required to perform the computation prior to the assignment.
void	visit(Predicate p) Process a node by calling its associated routine.

Methods inherited from class scale.clef.expr.DyadicOp

containsDeclaration, equivalent, getChild, getDeclList, getExpr1, getExpr2, getLhs, getRhs, isSimpleOp, numChildren, setExpr1, setExpr2, setLhs, setRhs

Methods inherited from class scale.clef.expr.Expression

canonical, getConstantValue, getCoreType, getDisplayColorHint, getDisplayLabel, getDisplayShapeHint, getPointedToCore, getType, hasTrueFalseResult, 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

CompoundAssignmentOp

public CompoundAssignmentOp(Type type,
                            Type calcType,
                            Expression lhs,
                            Expression ra)

Parameters:

type - is the type of the expression

calcType - is the type required for the right-hand-side computation

lhs - is the left-hand-side expression of the assignment

ra - is right argument to the right-hand-side expression of the assignment

Method Detail

getCalcType

public final Type getCalcType()

Return the type required to perform the computation prior to the assignment. For example, in

   int x;
   x = *= 0.5;
 

the computation x * 0.5 must be performed as (int) (((double) x) * 0.5). So, even though the type of the expression is int, the computational type is double.

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 AssignmentOp

See Also:

Predicate