gecko-dev/extensions/transformiix/source/xpath/BooleanExpr.cpp

113 lines
3.2 KiB
C++

/*
* The contents of this file are subject to the Mozilla Public
* License Version 1.1 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS
* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
* implied. See the License for the specific language governing
* rights and limitations under the License.
*
* The Original Code is TransforMiiX XSLT processor.
*
* The Initial Developer of the Original Code is The MITRE Corporation.
* Portions created by MITRE are Copyright (C) 1999 The MITRE Corporation.
*
* Portions created by Keith Visco as a Non MITRE employee,
* (C) 1999 Keith Visco. All Rights Reserved.
*
* Contributor(s):
* Keith Visco, kvisco@ziplink.net
* -- original author.
*
* Marc Schefer, schefer@xo3.com
* -- fixed a bug regarding Or expressions
* - If the left hand was false, the right hand expression
* was not getting checked.
*
*/
/**
* Represents a BooleanExpr, a binary expression that
* performs a boolean operation between it's lvalue and rvalue.
**/
#include "Expr.h"
/**
* Creates a new BooleanExpr using the given operator
**/
BooleanExpr::BooleanExpr(Expr* leftExpr, Expr* rightExpr, short op) {
this->op = op;
this->leftExpr = leftExpr;
this->rightExpr = rightExpr;
} //-- BooleanExpr
BooleanExpr::~BooleanExpr() {
delete leftExpr;
delete rightExpr;
} //-- ~BooleanExpr
/**
* Evaluates this Expr based on the given context node and processor state
* @param context the context node for evaluation of this Expr
* @param ps the ContextState containing the stack information needed
* for evaluation
* @return the result of the evaluation
**/
ExprResult* BooleanExpr::evaluate(Node* context, ContextState* cs) {
MBool lval = MB_FALSE;
ExprResult* exprRes = 0;
if ( leftExpr ) {
exprRes = leftExpr->evaluate(context, cs);
if ( exprRes ) lval = exprRes->booleanValue();
delete exprRes;
}
//-- check left expression for early decision
if (( op == OR ) && (lval)) return new BooleanResult(MB_TRUE);
else if ((op == AND) && (!lval)) return new BooleanResult(MB_FALSE);
MBool rval = MB_FALSE;
if ( rightExpr ) {
exprRes = rightExpr->evaluate(context, cs);
if ( exprRes ) rval = exprRes->booleanValue();
delete exprRes;
}
//-- just use rval, since we already checked lval
return new BooleanResult(rval);
} //-- evaluate
/**
* Returns the String representation of this Expr.
* @param dest the String to use when creating the String
* representation. The String representation will be appended to
* any data in the destination String, to allow cascading calls to
* other #toString() methods for Expressions.
* @return the String representation of this Expr.
**/
void BooleanExpr::toString(String& str) {
if ( leftExpr ) leftExpr->toString(str);
else str.append("null");
switch ( op ) {
case OR:
str.append(" or ");
break;
default:
str.append(" and ");
break;
}
if ( rightExpr ) rightExpr->toString(str);
else str.append("null");
} //-- toString