/*
* @(#)NotExpression.java 1.14 95/11/12 Arthur van Hoff
*
* Copyright (c) 1994 Sun Microsystems, Inc. All Rights Reserved.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package sun.tools.tree;
import sun.tools.java.*;
import sun.tools.asm.Assembler;
import sun.tools.asm.Label;
import java.util.Hashtable;
public
class NotExpression extends UnaryExpression {
/**
* Constructor
*/
public NotExpression(int where, Expression right) {
super(NOT, where, Type.tBoolean, right);
}
/**
* Select the type of the expression
*/
void selectType(Environment env, Context ctx, int tm) {
right = convert(env, ctx, Type.tBoolean, right);
}
/*
* Check a "not" expression.
*
* cvars is modified so that
* cvar.vsTrue indicates variables with a known value if
* the expression is true.
* cvars.vsFalse indicates variables with a known value if
* the expression is false
*
* For "not" expressions, we look at the inside expression, and then
* swap true and false.
*/
public void checkCondition(Environment env, Context ctx, int vset,
Hashtable exp, ConditionVars cvars) {
right.checkCondition(env, ctx, vset, exp, cvars);
right = convert(env, ctx, Type.tBoolean, right);
// swap true and false
long temp = cvars.vsFalse;
cvars.vsFalse = cvars.vsTrue;
cvars.vsTrue = temp;
}
/**
* Evaluate
*/
Expression eval(boolean a) {
return new BooleanExpression(where, !a);
}
/**
* Simplify
*/
Expression simplify() {
// Check if the expression can be optimized
switch (right.op) {
case NOT:
return ((NotExpression)right).right;
case EQ:
case NE:
case LT:
case LE:
case GT:
case GE:
break;
default:
return this;
}
// Can't negate real comparisons
BinaryExpression bin = (BinaryExpression)right;
if (bin.left.type.inMask(TM_REAL)) {
return this;
}
// Negate comparison
switch (right.op) {
case EQ:
return new NotEqualExpression(where, bin.left, bin.right);
case NE:
return new EqualExpression(where, bin.left, bin.right);
case LT:
return new GreaterOrEqualExpression(where, bin.left, bin.right);
case LE:
return new GreaterExpression(where, bin.left, bin.right);
case GT:
return new LessOrEqualExpression(where, bin.left, bin.right);
case GE:
return new LessExpression(where, bin.left, bin.right);
}
return this;
}
/**
* Code
*/
void codeBranch(Environment env, Context ctx, Assembler asm, Label lbl, boolean whenTrue) {
right.codeBranch(env, ctx, asm, lbl, !whenTrue);
}
}