BSD 4_1c_2 release

[unix-history] / usr / src / ucb / pascal / pdx / tree / tr_equal.c

/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)tr_equal.c 1.1 1/18/82";

/*
* A recursive tree search routine to test if two trees
* are structurally equivalent.
*/

#include "defs.h"
#include "tree.h"
#include "tree.rep"

BOOLEAN tr_equal(t1, t2)
register NODE *t1;
register NODE *t2;
{
       if (t1 == NIL && t2 == NIL) {
               return(TRUE);
       }
       if (t1 == NIL || t2 == NIL) {
               return(FALSE);
       }
       if (t1->op != t2->op || degree(t1->op) != degree(t2->op)) {
               return(FALSE);
       }
       switch(degree(t1->op)) {
               case LEAF:
                       switch(t1->op) {
                               case O_NAME:
                                       return(t1->nameval == t2->nameval);

                               case O_QNAME:
                                       if (!tr_equal(t1->right, t2->right)) {
                                               return(FALSE);
                                       }
                                       return(tr_equal(t1->left, t2->left));

                               case O_LCON:
                                       return(t1->lconval == t2->lconval);

                               case O_FCON:
                                       return(t1->fconval == t2->fconval);

                               case O_SCON:
                                       return(t1->sconval == t2->sconval);

                               default:
                                       panic("tr_equal: leaf %d\n", t1->op);
                       }
                       /*NOTREACHED*/

               case BINARY:
                       if (!tr_equal(t1->right, t2->right)) {
                               return(FALSE);
                       }
                       /* else fall through */
               case UNARY:
                       return(tr_equal(t1->left, t2->left));

               default:
                       panic("tr_equal: bad degree for op %d\n", t1->op);
       }
       /*NOTREACHED*/
}