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Java > Open Source Codes > Tboolexp


1 /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
2  * Copyright (C) 2001 Gerwin Klein <lsf@jflex.de> *
3  * Copyright (C) 2001 Bernhard Rumpe <rumpe@in.tum.de> *
4  * All rights reserved. *
5  * *
6  * This program is free software; you can redistribute it and/or modify *
7  * it under the terms of the GNU General Public License. See the file *
8  * COPYRIGHT for more information. *
9  * *
10  * This program is distributed in the hope that it will be useful, *
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of *
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
13  * GNU General Public License for more details. *
14  * *
15  * You should have received a copy of the GNU General Public License along *
16  * with this program; if not, write to the Free Software Foundation, Inc., *
17  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA *
18  * *
19  * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
20
21
22 /**
23  * AST node for bool expressions
24  */
25 class Tboolexp implements AST {
26   Texp exp1, exp2; // left and right subexpression
27 char kind; // '=', '<' and '!' for "<="
28
29   public Tboolexp(Texp e1, char k, Texp e2) {
30     exp1=e1;
31     kind=k;
32     exp2=e2;
33   }
34
35   public String JavaDoc toString() {
36     if (kind!='!')
37       return(""+exp1+kind+exp2);
38     else
39       return(exp1+"<="+exp2);
40   }
41
42   public void checkcontext(SymTab st) { // context conditions
43 exp1.checkcontext(st);
44     exp2.checkcontext(st);
45   }
46
47   public void prepInterp(SymTab st) { // set pointers and indices
48 exp1.prepInterp(st);
49     exp2.prepInterp(st);
50   }
51
52   public boolean interpret(int[] in, int[] par) {
53     int e1 = exp1.interpret(in,par);
54     int e2 = exp2.interpret(in,par);
55     switch(kind) {
56     case '=': return(e1==e2);
57     case '<': return(e1<e2);
58     case '!': return(e1<=e2);
59     }
60
61     return(false); // error
62 }
63 }
64
65
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