401 lines
8.2 KiB
C
401 lines
8.2 KiB
C
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/***** tl_spin: tl_parse.c *****/
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/* Copyright (c) 1995-2003 by Lucent Technologies, Bell Laboratories. */
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/* All Rights Reserved. This software is for educational purposes only. */
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/* No guarantee whatsoever is expressed or implied by the distribution of */
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/* this code. Permission is given to distribute this code provided that */
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/* this introductory message is not removed and no monies are exchanged. */
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/* Software written by Gerard J. Holzmann. For tool documentation see: */
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/* http://spinroot.com/ */
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/* Send all bug-reports and/or questions to: bugs@spinroot.com */
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/* Based on the translation algorithm by Gerth, Peled, Vardi, and Wolper, */
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/* presented at the PSTV Conference, held in 1995, Warsaw, Poland 1995. */
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#include "tl.h"
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extern int tl_yylex(void);
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extern int tl_verbose, tl_errs;
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int tl_yychar = 0;
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YYSTYPE tl_yylval;
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static Node *tl_formula(void);
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static Node *tl_factor(void);
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static Node *tl_level(int);
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static int prec[2][4] = {
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{ U_OPER, V_OPER, 0, 0 }, /* left associative */
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{ OR, AND, IMPLIES, EQUIV, }, /* left associative */
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};
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static Node *
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tl_factor(void)
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{ Node *ptr = ZN;
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switch (tl_yychar) {
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case '(':
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ptr = tl_formula();
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if (tl_yychar != ')')
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tl_yyerror("expected ')'");
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tl_yychar = tl_yylex();
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break;
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case NOT:
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ptr = tl_yylval;
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tl_yychar = tl_yylex();
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ptr->lft = tl_factor();
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ptr = push_negation(ptr);
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break;
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case ALWAYS:
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tl_yychar = tl_yylex();
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ptr = tl_factor();
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#ifndef NO_OPT
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if (ptr->ntyp == FALSE
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|| ptr->ntyp == TRUE)
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break; /* [] false == false */
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if (ptr->ntyp == V_OPER)
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{ if (ptr->lft->ntyp == FALSE)
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break; /* [][]p = []p */
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ptr = ptr->rgt; /* [] (p V q) = [] q */
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}
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#endif
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ptr = tl_nn(V_OPER, False, ptr);
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break;
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#ifdef NXT
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case NEXT:
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tl_yychar = tl_yylex();
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ptr = tl_factor();
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if (ptr->ntyp == TRUE)
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break; /* X true = true */
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ptr = tl_nn(NEXT, ptr, ZN);
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break;
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#endif
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case EVENTUALLY:
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tl_yychar = tl_yylex();
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ptr = tl_factor();
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#ifndef NO_OPT
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if (ptr->ntyp == TRUE
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|| ptr->ntyp == FALSE)
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break; /* <> true == true */
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if (ptr->ntyp == U_OPER
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&& ptr->lft->ntyp == TRUE)
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break; /* <><>p = <>p */
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if (ptr->ntyp == U_OPER)
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{ /* <> (p U q) = <> q */
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ptr = ptr->rgt;
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/* fall thru */
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}
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#endif
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ptr = tl_nn(U_OPER, True, ptr);
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break;
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case PREDICATE:
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ptr = tl_yylval;
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tl_yychar = tl_yylex();
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break;
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case TRUE:
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case FALSE:
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ptr = tl_yylval;
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tl_yychar = tl_yylex();
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break;
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}
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if (!ptr) tl_yyerror("expected predicate");
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#if 0
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printf("factor: ");
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tl_explain(ptr->ntyp);
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printf("\n");
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#endif
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return ptr;
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}
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static Node *
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bin_simpler(Node *ptr)
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{ Node *a, *b;
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if (ptr)
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switch (ptr->ntyp) {
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case U_OPER:
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#ifndef NO_OPT
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if (ptr->rgt->ntyp == TRUE
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|| ptr->rgt->ntyp == FALSE
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|| ptr->lft->ntyp == FALSE)
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{ ptr = ptr->rgt;
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break;
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}
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if (isequal(ptr->lft, ptr->rgt))
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{ /* p U p = p */
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ptr = ptr->rgt;
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break;
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}
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if (ptr->lft->ntyp == U_OPER
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&& isequal(ptr->lft->lft, ptr->rgt))
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{ /* (p U q) U p = (q U p) */
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ptr->lft = ptr->lft->rgt;
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break;
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}
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if (ptr->rgt->ntyp == U_OPER
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&& ptr->rgt->lft->ntyp == TRUE)
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{ /* p U (T U q) = (T U q) */
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ptr = ptr->rgt;
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break;
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}
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#ifdef NXT
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/* X p U X q == X (p U q) */
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if (ptr->rgt->ntyp == NEXT
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&& ptr->lft->ntyp == NEXT)
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{ ptr = tl_nn(NEXT,
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tl_nn(U_OPER,
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ptr->lft->lft,
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ptr->rgt->lft), ZN);
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}
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#endif
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#endif
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break;
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case V_OPER:
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#ifndef NO_OPT
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if (ptr->rgt->ntyp == FALSE
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|| ptr->rgt->ntyp == TRUE
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|| ptr->lft->ntyp == TRUE)
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{ ptr = ptr->rgt;
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break;
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}
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if (isequal(ptr->lft, ptr->rgt))
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{ /* p V p = p */
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ptr = ptr->rgt;
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break;
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}
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/* F V (p V q) == F V q */
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if (ptr->lft->ntyp == FALSE
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&& ptr->rgt->ntyp == V_OPER)
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{ ptr->rgt = ptr->rgt->rgt;
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break;
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}
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/* p V (F V q) == F V q */
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if (ptr->rgt->ntyp == V_OPER
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&& ptr->rgt->lft->ntyp == FALSE)
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{ ptr->lft = False;
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ptr->rgt = ptr->rgt->rgt;
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break;
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}
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#endif
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break;
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case IMPLIES:
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#ifndef NO_OPT
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if (isequal(ptr->lft, ptr->rgt))
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{ ptr = True;
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break;
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}
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#endif
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ptr = tl_nn(OR, Not(ptr->lft), ptr->rgt);
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ptr = rewrite(ptr);
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break;
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case EQUIV:
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#ifndef NO_OPT
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if (isequal(ptr->lft, ptr->rgt))
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{ ptr = True;
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break;
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}
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#endif
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a = rewrite(tl_nn(AND,
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dupnode(ptr->lft),
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dupnode(ptr->rgt)));
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b = rewrite(tl_nn(AND,
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Not(ptr->lft),
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Not(ptr->rgt)));
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ptr = tl_nn(OR, a, b);
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ptr = rewrite(ptr);
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break;
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case AND:
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#ifndef NO_OPT
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/* p && (q U p) = p */
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if (ptr->rgt->ntyp == U_OPER
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&& isequal(ptr->rgt->rgt, ptr->lft))
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{ ptr = ptr->lft;
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break;
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}
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if (ptr->lft->ntyp == U_OPER
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&& isequal(ptr->lft->rgt, ptr->rgt))
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{ ptr = ptr->rgt;
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break;
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}
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/* p && (q V p) == q V p */
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if (ptr->rgt->ntyp == V_OPER
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&& isequal(ptr->rgt->rgt, ptr->lft))
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{ ptr = ptr->rgt;
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break;
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}
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if (ptr->lft->ntyp == V_OPER
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&& isequal(ptr->lft->rgt, ptr->rgt))
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{ ptr = ptr->lft;
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break;
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}
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/* (p U q) && (r U q) = (p && r) U q*/
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if (ptr->rgt->ntyp == U_OPER
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&& ptr->lft->ntyp == U_OPER
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&& isequal(ptr->rgt->rgt, ptr->lft->rgt))
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{ ptr = tl_nn(U_OPER,
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tl_nn(AND, ptr->lft->lft, ptr->rgt->lft),
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ptr->lft->rgt);
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break;
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}
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/* (p V q) && (p V r) = p V (q && r) */
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if (ptr->rgt->ntyp == V_OPER
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&& ptr->lft->ntyp == V_OPER
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&& isequal(ptr->rgt->lft, ptr->lft->lft))
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{ ptr = tl_nn(V_OPER,
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ptr->rgt->lft,
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tl_nn(AND, ptr->lft->rgt, ptr->rgt->rgt));
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break;
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}
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#ifdef NXT
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/* X p && X q == X (p && q) */
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if (ptr->rgt->ntyp == NEXT
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&& ptr->lft->ntyp == NEXT)
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{ ptr = tl_nn(NEXT,
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tl_nn(AND,
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ptr->rgt->lft,
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ptr->lft->lft), ZN);
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break;
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}
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#endif
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if (isequal(ptr->lft, ptr->rgt) /* (p && p) == p */
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|| ptr->rgt->ntyp == FALSE /* (p && F) == F */
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|| ptr->lft->ntyp == TRUE) /* (T && p) == p */
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{ ptr = ptr->rgt;
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break;
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}
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if (ptr->rgt->ntyp == TRUE /* (p && T) == p */
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|| ptr->lft->ntyp == FALSE) /* (F && p) == F */
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{ ptr = ptr->lft;
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break;
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}
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/* (p V q) && (r U q) == p V q */
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if (ptr->rgt->ntyp == U_OPER
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&& ptr->lft->ntyp == V_OPER
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&& isequal(ptr->lft->rgt, ptr->rgt->rgt))
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{ ptr = ptr->lft;
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break;
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}
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#endif
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break;
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case OR:
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#ifndef NO_OPT
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/* p || (q U p) == q U p */
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if (ptr->rgt->ntyp == U_OPER
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&& isequal(ptr->rgt->rgt, ptr->lft))
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{ ptr = ptr->rgt;
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break;
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}
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/* p || (q V p) == p */
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if (ptr->rgt->ntyp == V_OPER
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&& isequal(ptr->rgt->rgt, ptr->lft))
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{ ptr = ptr->lft;
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break;
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}
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/* (p U q) || (p U r) = p U (q || r) */
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if (ptr->rgt->ntyp == U_OPER
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&& ptr->lft->ntyp == U_OPER
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&& isequal(ptr->rgt->lft, ptr->lft->lft))
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{ ptr = tl_nn(U_OPER,
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ptr->rgt->lft,
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tl_nn(OR, ptr->lft->rgt, ptr->rgt->rgt));
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break;
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}
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if (isequal(ptr->lft, ptr->rgt) /* (p || p) == p */
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|| ptr->rgt->ntyp == FALSE /* (p || F) == p */
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|| ptr->lft->ntyp == TRUE) /* (T || p) == T */
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{ ptr = ptr->lft;
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break;
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}
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if (ptr->rgt->ntyp == TRUE /* (p || T) == T */
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|| ptr->lft->ntyp == FALSE) /* (F || p) == p */
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{ ptr = ptr->rgt;
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break;
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}
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/* (p V q) || (r V q) = (p || r) V q */
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if (ptr->rgt->ntyp == V_OPER
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&& ptr->lft->ntyp == V_OPER
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&& isequal(ptr->lft->rgt, ptr->rgt->rgt))
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{ ptr = tl_nn(V_OPER,
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tl_nn(OR, ptr->lft->lft, ptr->rgt->lft),
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ptr->rgt->rgt);
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break;
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}
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/* (p V q) || (r U q) == r U q */
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if (ptr->rgt->ntyp == U_OPER
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&& ptr->lft->ntyp == V_OPER
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&& isequal(ptr->lft->rgt, ptr->rgt->rgt))
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{ ptr = ptr->rgt;
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break;
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}
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#endif
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break;
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}
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return ptr;
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}
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static Node *
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tl_level(int nr)
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{ int i; Node *ptr = ZN;
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if (nr < 0)
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return tl_factor();
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ptr = tl_level(nr-1);
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again:
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for (i = 0; i < 4; i++)
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if (tl_yychar == prec[nr][i])
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{ tl_yychar = tl_yylex();
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ptr = tl_nn(prec[nr][i],
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ptr, tl_level(nr-1));
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ptr = bin_simpler(ptr);
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goto again;
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}
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if (!ptr) tl_yyerror("syntax error");
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#if 0
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printf("level %d: ", nr);
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tl_explain(ptr->ntyp);
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printf("\n");
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#endif
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return ptr;
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}
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static Node *
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tl_formula(void)
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{ tl_yychar = tl_yylex();
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return tl_level(1); /* 2 precedence levels, 1 and 0 */
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}
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void
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tl_parse(void)
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{ Node *n = tl_formula();
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if (tl_verbose)
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{ printf("formula: ");
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dump(n);
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printf("\n");
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}
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if (tl_Getchar() != -1)
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{ tl_yyerror("syntax error");
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tl_errs++;
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return;
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}
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trans(n);
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}
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