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/*======================================================================
DESIREDRDR(; F,t)
Desired cell condition read, robust.
\Output
\parm{F} is a condition for desired cells.
\parm{t} is 1 if successful, 0 otherwise.
======================================================================*/
#include "qepcad.h"
void DESIREDRDR(Word *F_, Word *t_)
{
Word C,C1,F,F1,F2,R,V1,V2,p,t;
/* hide C,C1,R,V1,V2,t; */
Step1: /* Atomic condition. */
F = NIL;
t = 1;
C = CREADB(); if (C == '[') goto Step2;
BKSP();
if (DIGIT(C))
V1 = AREAD();
else
{CATTRNRDR(&V1,&t); if (t == 0) goto Return;}
RLOPRDR(&R,&t); if (t == 0) goto Return;
C = CREADB(); BKSP();
if (DIGIT(C))
V2 = AREAD();
else
{CATTRNRDR(&V2,&t); if (t == 0) goto Return;}
F = LIST3(R,V1,V2);
goto Return;
Step2: /* Negation. */
C = CREADB(); if (C != '~') { BKSP(); goto Step3; }
DESIREDRDR(&F1,&t); if (t == 0) goto Return;
C = CREADB();
if (C != ']')
{ SWRITE("Error DESIREDRDR: ']' was expected.\n"); goto Step11; }
F = LIST2(NOTOP,F1); goto Return;
Step3: /* Read in the first formula. */
DESIREDRDR(&F1,&t); if (t == 0) goto Return;
Step4: /* Redundant square brakets. */
C = CREADB(); if (C == ']') { F = F1; goto Return; }
BKSP();
Step5: /* Indentify the logical operator. */
LGOPRDR(&p,&t); if (t == 0) goto Return;
switch (p)
{
case ANDOP: goto Step6; break;
case OROP: goto Step7; break;
case RIGHTOP: goto Step8; break;
case LEFTOP: goto Step9; break;
case EQUIOP: goto Step10; break;
case NOTOP: {
SWRITE("Error DESIREDRDR: '~' must not be here.\n");
goto Step11;
}
}
Step6: /* Conjunction. */
F = LIST2(F1,ANDOP);
do
{
DESIREDRDR(&F2,&t); if (t == 0) goto Return;
F = COMP(F2,F);
C1 = CREADB();
if (C1 == ']') { F = INV(F); goto Return; }
BKSP(); LGOPRDR(&p,&t); if (t == 0) goto Return;
if (p != ANDOP)
{ SWRITE("Error DESIREDRDR: '/\\' was expected.\n"); goto Step11; }
}
while (1);
Step7: /* Disjunction. */
F = LIST2(F1,OROP);
do
{
DESIREDRDR(&F2,&t); if (t == 0) goto Return;
F = COMP(F2,F);
C1 = CREADB();
if (C1 == ']') { F = INV(F); goto Return; }
BKSP(); LGOPRDR(&p,&t); if (t == 0) goto Return;
if (p != OROP)
{ SWRITE("Error DESIREDRDR: '\\/' was expected.\n"); goto Step11; }
}
while (1);
Step8: /* $\Rightarrow$. */
DESIREDRDR(&F2,&t); if (t == 0) goto Return;
C = CREADB();
if (C != ']') { SWRITE("Error DESIREDRDR: ']' was expected.\n"); goto Step11; }
F = LIST3(RIGHTOP,F1,F2); goto Return;
Step9: /* $\Leftarrow$. */
DESIREDRDR(&F2,&t); if (t == 0) goto Return;
C = CREADB();
if (C != ']') { SWRITE("Error DESIREDRDR: ']' was expected.\n"); goto Step11; }
F = LIST3(LEFTOP,F1,F2); goto Return;
Step10: /* $\LeftRightarrow$. */
DESIREDRDR(&F2,&t); if (t == 0) goto Return;
C = CREADB();
if (C != ']') { SWRITE("Error DESIREDRDR: ']' was expected.\n"); goto Step11; }
F = LIST3(EQUIOP,F1,F2); goto Return;
Step11: /* Error exit. */
DIELOC(); t = 0; goto Return;
Return: /* Prepare for return. */
*F_ = F;
*t_ = t;
return;
}
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