ltl2ba-nix/parse.c

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/***** ltl2ba : parse.c *****/
/* Written by Denis Oddoux, LIAFA, France */
/* Copyright (c) 2001 Denis Oddoux */
/* Modified by Paul Gastin, LSV, France */
/* Copyright (c) 2007 Paul Gastin */
/* */
/* This program is free software; you can redistribute it and/or modify */
/* it under the terms of the GNU General Public License as published by */
/* the Free Software Foundation; either version 2 of the License, or */
/* (at your option) any later version. */
/* */
/* This program is distributed in the hope that it will be useful, */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the */
/* GNU General Public License for more details. */
/* */
/* You should have received a copy of the GNU General Public License */
/* along with this program; if not, write to the Free Software */
/* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA*/
/* */
/* Based on the translation algorithm by Gastin and Oddoux, */
/* presented at the 13th International Conference on Computer Aided */
/* Verification, CAV 2001, Paris, France. */
/* Proceedings - LNCS 2102, pp. 53-65 */
/* */
/* Send bug-reports and/or questions to Paul Gastin */
/* http://www.lsv.ens-cachan.fr/~gastin */
/* */
/* Some of the code in this file was taken from the Spin software */
/* Written by Gerard J. Holzmann, Bell Laboratories, U.S.A. */
2018-08-09 10:46:27 +02:00
#include "config.h"
#include "ltl2ba.h"
extern int tl_verbose, tl_simp_log;
int tl_yychar = 0;
YYSTYPE tl_yylval;
static Node *tl_formula(void);
static Node *tl_factor(void);
static Node *tl_level(int);
static int prec[2][4] = {
{ U_OPER, V_OPER, 0, 0}, /* left associative */
{ OR, AND, IMPLIES, EQUIV, }, /* left associative */
};
static int
implies(Node *a, Node *b)
{
return
(isequal(a,b) ||
b->ntyp == TRUE ||
a->ntyp == FALSE ||
(b->ntyp == AND && implies(a, b->lft) && implies(a, b->rgt)) ||
(a->ntyp == OR && implies(a->lft, b) && implies(a->rgt, b)) ||
(a->ntyp == AND && (implies(a->lft, b) || implies(a->rgt, b))) ||
(b->ntyp == OR && (implies(a, b->lft) || implies(a, b->rgt))) ||
(b->ntyp == U_OPER && implies(a, b->rgt)) ||
(a->ntyp == V_OPER && implies(a->rgt, b)) ||
(a->ntyp == U_OPER && implies(a->lft, b) && implies(a->rgt, b)) ||
(b->ntyp == V_OPER && implies(a, b->lft) && implies(a, b->rgt)) ||
((a->ntyp == U_OPER || a->ntyp == V_OPER) && a->ntyp == b->ntyp &&
implies(a->lft, b->lft) && implies(a->rgt, b->rgt)));
}
static Node *
bin_simpler(Node *ptr)
{ Node *a, *b;
if (ptr)
switch (ptr->ntyp) {
case U_OPER:
if (ptr->rgt->ntyp == TRUE
|| ptr->rgt->ntyp == FALSE
|| ptr->lft->ntyp == FALSE)
{ ptr = ptr->rgt;
break;
}
if (implies(ptr->lft, ptr->rgt)) /* NEW */
{ ptr = ptr->rgt;
break;
}
if (ptr->lft->ntyp == U_OPER
&& isequal(ptr->lft->lft, ptr->rgt))
{ /* (p U q) U p = (q U p) */
ptr->lft = ptr->lft->rgt;
break;
}
if (ptr->rgt->ntyp == U_OPER
&& implies(ptr->lft, ptr->rgt->lft))
{ /* NEW */
ptr = ptr->rgt;
break;
}
#ifdef NXT
/* X p U X q == X (p U q) */
if (ptr->rgt->ntyp == NEXT
&& ptr->lft->ntyp == NEXT)
{ ptr = tl_nn(NEXT,
tl_nn(U_OPER,
ptr->lft->lft,
ptr->rgt->lft), ZN);
break;
}
/* NEW : F X p == X F p */
if (ptr->lft->ntyp == TRUE &&
ptr->rgt->ntyp == NEXT) {
ptr = tl_nn(NEXT, tl_nn(U_OPER, True, ptr->rgt->lft), ZN);
break;
}
#endif
/* NEW : F G F p == G F p */
if (ptr->lft->ntyp == TRUE &&
ptr->rgt->ntyp == V_OPER &&
ptr->rgt->lft->ntyp == FALSE &&
ptr->rgt->rgt->ntyp == U_OPER &&
ptr->rgt->rgt->lft->ntyp == TRUE) {
ptr = ptr->rgt;
break;
}
/* NEW */
if (ptr->lft->ntyp != TRUE &&
implies(push_negation(tl_nn(NOT, dupnode(ptr->rgt), ZN)),
ptr->lft))
{ ptr->lft = True;
break;
}
break;
case V_OPER:
if (ptr->rgt->ntyp == FALSE
|| ptr->rgt->ntyp == TRUE
|| ptr->lft->ntyp == TRUE)
{ ptr = ptr->rgt;
break;
}
if (implies(ptr->rgt, ptr->lft))
{ /* p V p = p */
ptr = ptr->rgt;
break;
}
/* F V (p V q) == F V q */
if (ptr->lft->ntyp == FALSE
&& ptr->rgt->ntyp == V_OPER)
{ ptr->rgt = ptr->rgt->rgt;
break;
}
#ifdef NXT
/* NEW : G X p == X G p */
if (ptr->lft->ntyp == FALSE &&
ptr->rgt->ntyp == NEXT) {
ptr = tl_nn(NEXT, tl_nn(V_OPER, False, ptr->rgt->lft), ZN);
break;
}
#endif
/* NEW : G F G p == F G p */
if (ptr->lft->ntyp == FALSE &&
ptr->rgt->ntyp == U_OPER &&
ptr->rgt->lft->ntyp == TRUE &&
ptr->rgt->rgt->ntyp == V_OPER &&
ptr->rgt->rgt->lft->ntyp == FALSE) {
ptr = ptr->rgt;
break;
}
/* NEW */
if (ptr->rgt->ntyp == V_OPER
&& implies(ptr->rgt->lft, ptr->lft))
{ ptr = ptr->rgt;
break;
}
/* NEW */
if (ptr->lft->ntyp != FALSE &&
implies(ptr->lft,
push_negation(tl_nn(NOT, dupnode(ptr->rgt), ZN))))
{ ptr->lft = False;
break;
}
break;
#ifdef NXT
case NEXT:
/* NEW : X G F p == G F p */
if (ptr->lft->ntyp == V_OPER &&
ptr->lft->lft->ntyp == FALSE &&
ptr->lft->rgt->ntyp == U_OPER &&
ptr->lft->rgt->lft->ntyp == TRUE) {
ptr = ptr->lft;
break;
}
/* NEW : X F G p == F G p */
if (ptr->lft->ntyp == U_OPER &&
ptr->lft->lft->ntyp == TRUE &&
ptr->lft->rgt->ntyp == V_OPER &&
ptr->lft->rgt->lft->ntyp == FALSE) {
ptr = ptr->lft;
break;
}
break;
#endif
case IMPLIES:
if (implies(ptr->lft, ptr->rgt))
{ ptr = True;
break;
}
ptr = tl_nn(OR, Not(ptr->lft), ptr->rgt);
ptr = rewrite(ptr);
break;
case EQUIV:
if (implies(ptr->lft, ptr->rgt) &&
implies(ptr->rgt, ptr->lft))
{ ptr = True;
break;
}
a = rewrite(tl_nn(AND,
dupnode(ptr->lft),
dupnode(ptr->rgt)));
b = rewrite(tl_nn(AND,
Not(ptr->lft),
Not(ptr->rgt)));
ptr = tl_nn(OR, a, b);
ptr = rewrite(ptr);
break;
case AND:
/* p && (q U p) = p */
if (ptr->rgt->ntyp == U_OPER
&& isequal(ptr->rgt->rgt, ptr->lft))
{ ptr = ptr->lft;
break;
}
if (ptr->lft->ntyp == U_OPER
&& isequal(ptr->lft->rgt, ptr->rgt))
{ ptr = ptr->rgt;
break;
}
/* p && (q V p) == q V p */
if (ptr->rgt->ntyp == V_OPER
&& isequal(ptr->rgt->rgt, ptr->lft))
{ ptr = ptr->rgt;
break;
}
if (ptr->lft->ntyp == V_OPER
&& isequal(ptr->lft->rgt, ptr->rgt))
{ ptr = ptr->lft;
break;
}
/* (p U q) && (r U q) = (p && r) U q*/
if (ptr->rgt->ntyp == U_OPER
&& ptr->lft->ntyp == U_OPER
&& isequal(ptr->rgt->rgt, ptr->lft->rgt))
{ ptr = tl_nn(U_OPER,
tl_nn(AND, ptr->lft->lft, ptr->rgt->lft),
ptr->lft->rgt);
break;
}
/* (p V q) && (p V r) = p V (q && r) */
if (ptr->rgt->ntyp == V_OPER
&& ptr->lft->ntyp == V_OPER
&& isequal(ptr->rgt->lft, ptr->lft->lft))
{ ptr = tl_nn(V_OPER,
ptr->rgt->lft,
tl_nn(AND, ptr->lft->rgt, ptr->rgt->rgt));
break;
}
#ifdef NXT
/* X p && X q == X (p && q) */
if (ptr->rgt->ntyp == NEXT
&& ptr->lft->ntyp == NEXT)
{ ptr = tl_nn(NEXT,
tl_nn(AND,
ptr->rgt->lft,
ptr->lft->lft), ZN);
break;
}
#endif
/* (p V q) && (r U q) == p V q */
if (ptr->rgt->ntyp == U_OPER
&& ptr->lft->ntyp == V_OPER
&& isequal(ptr->lft->rgt, ptr->rgt->rgt))
{ ptr = ptr->lft;
break;
}
if (isequal(ptr->lft, ptr->rgt) /* (p && p) == p */
|| ptr->rgt->ntyp == FALSE /* (p && F) == F */
|| ptr->lft->ntyp == TRUE /* (T && p) == p */
|| implies(ptr->rgt, ptr->lft))/* NEW */
{ ptr = ptr->rgt;
break;
}
if (ptr->rgt->ntyp == TRUE /* (p && T) == p */
|| ptr->lft->ntyp == FALSE /* (F && p) == F */
|| implies(ptr->lft, ptr->rgt))/* NEW */
{ ptr = ptr->lft;
break;
}
/* NEW : F G p && F G q == F G (p && q) */
if (ptr->lft->ntyp == U_OPER &&
ptr->lft->lft->ntyp == TRUE &&
ptr->lft->rgt->ntyp == V_OPER &&
ptr->lft->rgt->lft->ntyp == FALSE &&
ptr->rgt->ntyp == U_OPER &&
ptr->rgt->lft->ntyp == TRUE &&
ptr->rgt->rgt->ntyp == V_OPER &&
ptr->rgt->rgt->lft->ntyp == FALSE)
{
ptr = tl_nn(U_OPER, True,
tl_nn(V_OPER, False,
tl_nn(AND, ptr->lft->rgt->rgt,
ptr->rgt->rgt->rgt)));
break;
}
/* NEW */
if (implies(ptr->lft,
push_negation(tl_nn(NOT, dupnode(ptr->rgt), ZN)))
|| implies(ptr->rgt,
push_negation(tl_nn(NOT, dupnode(ptr->lft), ZN))))
{ ptr = False;
break;
}
break;
case OR:
/* p || (q U p) == q U p */
if (ptr->rgt->ntyp == U_OPER
&& isequal(ptr->rgt->rgt, ptr->lft))
{ ptr = ptr->rgt;
break;
}
/* p || (q V p) == p */
if (ptr->rgt->ntyp == V_OPER
&& isequal(ptr->rgt->rgt, ptr->lft))
{ ptr = ptr->lft;
break;
}
/* (p U q) || (p U r) = p U (q || r) */
if (ptr->rgt->ntyp == U_OPER
&& ptr->lft->ntyp == U_OPER
&& isequal(ptr->rgt->lft, ptr->lft->lft))
{ ptr = tl_nn(U_OPER,
ptr->rgt->lft,
tl_nn(OR, ptr->lft->rgt, ptr->rgt->rgt));
break;
}
if (isequal(ptr->lft, ptr->rgt) /* (p || p) == p */
|| ptr->rgt->ntyp == FALSE /* (p || F) == p */
|| ptr->lft->ntyp == TRUE /* (T || p) == T */
|| implies(ptr->rgt, ptr->lft))/* NEW */
{ ptr = ptr->lft;
break;
}
if (ptr->rgt->ntyp == TRUE /* (p || T) == T */
|| ptr->lft->ntyp == FALSE /* (F || p) == p */
|| implies(ptr->lft, ptr->rgt))/* NEW */
{ ptr = ptr->rgt;
break;
}
/* (p V q) || (r V q) = (p || r) V q */
if (ptr->rgt->ntyp == V_OPER
&& ptr->lft->ntyp == V_OPER
&& isequal(ptr->lft->rgt, ptr->rgt->rgt))
{ ptr = tl_nn(V_OPER,
tl_nn(OR, ptr->lft->lft, ptr->rgt->lft),
ptr->rgt->rgt);
break;
}
/* (p V q) || (r U q) == r U q */
if (ptr->rgt->ntyp == U_OPER
&& ptr->lft->ntyp == V_OPER
&& isequal(ptr->lft->rgt, ptr->rgt->rgt))
{ ptr = ptr->rgt;
break;
}
/* NEW : G F p || G F q == G F (p || q) */
if (ptr->lft->ntyp == V_OPER &&
ptr->lft->lft->ntyp == FALSE &&
ptr->lft->rgt->ntyp == U_OPER &&
ptr->lft->rgt->lft->ntyp == TRUE &&
ptr->rgt->ntyp == V_OPER &&
ptr->rgt->lft->ntyp == FALSE &&
ptr->rgt->rgt->ntyp == U_OPER &&
ptr->rgt->rgt->lft->ntyp == TRUE)
{
ptr = tl_nn(V_OPER, False,
tl_nn(U_OPER, True,
tl_nn(OR, ptr->lft->rgt->rgt,
ptr->rgt->rgt->rgt)));
break;
}
/* NEW */
if (implies(push_negation(tl_nn(NOT, dupnode(ptr->rgt), ZN)),
ptr->lft)
|| implies(push_negation(tl_nn(NOT, dupnode(ptr->lft), ZN)),
ptr->rgt))
{ ptr = True;
break;
}
break;
}
return ptr;
}
static Node *
bin_minimal(Node *ptr)
{ if (ptr)
switch (ptr->ntyp) {
case IMPLIES:
return tl_nn(OR, Not(ptr->lft), ptr->rgt);
case EQUIV:
return tl_nn(OR,
tl_nn(AND,dupnode(ptr->lft),dupnode(ptr->rgt)),
tl_nn(AND,Not(ptr->lft),Not(ptr->rgt)));
}
return ptr;
}
static Node *
tl_factor(void)
{ Node *ptr = ZN;
switch (tl_yychar) {
case '(':
ptr = tl_formula();
if (tl_yychar != ')')
tl_yyerror("expected ')'");
tl_yychar = tl_yylex();
goto simpl;
case NOT:
ptr = tl_yylval;
tl_yychar = tl_yylex();
ptr->lft = tl_factor();
ptr = push_negation(ptr);
goto simpl;
case ALWAYS:
tl_yychar = tl_yylex();
ptr = tl_factor();
if(tl_simp_log) {
if (ptr->ntyp == FALSE
|| ptr->ntyp == TRUE)
break; /* [] false == false */
if (ptr->ntyp == V_OPER)
{ if (ptr->lft->ntyp == FALSE)
break; /* [][]p = []p */
ptr = ptr->rgt; /* [] (p V q) = [] q */
}
}
ptr = tl_nn(V_OPER, False, ptr);
goto simpl;
#ifdef NXT
case NEXT:
tl_yychar = tl_yylex();
ptr = tl_factor();
if ((ptr->ntyp == TRUE || ptr->ntyp == FALSE)&& tl_simp_log)
break; /* X true = true , X false = false */
ptr = tl_nn(NEXT, ptr, ZN);
goto simpl;
#endif
case EVENTUALLY:
tl_yychar = tl_yylex();
ptr = tl_factor();
if(tl_simp_log) {
if (ptr->ntyp == TRUE
|| ptr->ntyp == FALSE)
break; /* <> true == true */
if (ptr->ntyp == U_OPER
&& ptr->lft->ntyp == TRUE)
break; /* <><>p = <>p */
if (ptr->ntyp == U_OPER)
{ /* <> (p U q) = <> q */
ptr = ptr->rgt;
/* fall thru */
}
}
ptr = tl_nn(U_OPER, True, ptr);
simpl:
if (tl_simp_log)
ptr = bin_simpler(ptr);
break;
case PREDICATE:
ptr = tl_yylval;
tl_yychar = tl_yylex();
break;
case TRUE:
case FALSE:
ptr = tl_yylval;
tl_yychar = tl_yylex();
break;
}
if (!ptr) tl_yyerror("expected predicate");
#if 0
printf("factor: ");
tl_explain(ptr->ntyp);
printf("\n");
#endif
return ptr;
}
static Node *
tl_level(int nr)
{ int i; Node *ptr = ZN;
if (nr < 0)
return tl_factor();
ptr = tl_level(nr-1);
again:
for (i = 0; i < 4; i++)
if (tl_yychar == prec[nr][i])
{ tl_yychar = tl_yylex();
ptr = tl_nn(prec[nr][i],
ptr, tl_level(nr-1));
if(tl_simp_log) ptr = bin_simpler(ptr);
else ptr = bin_minimal(ptr);
goto again;
}
if (!ptr) tl_yyerror("syntax error");
#if 0
printf("level %d: ", nr);
tl_explain(ptr->ntyp);
printf("\n");
#endif
return ptr;
}
static Node *
tl_formula(void)
{ tl_yychar = tl_yylex();
return tl_level(1); /* 2 precedence levels, 1 and 0 */
}
void
tl_parse(void)
{ Node *n = tl_formula();
if (tl_verbose)
{ printf("formula: ");
put_uform();
printf("\n");
}
trans(n);
}