minix/external/bsd/byacc/dist/test/calc1.y

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2012-06-06 15:25:48 +02:00
/* $NetBSD: calc1.y,v 1.1.1.3 2011/09/10 21:22:09 christos Exp $ */
%{
/* http://dinosaur.compilertools.net/yacc/index.html */
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <math.h>
typedef struct interval
{
double lo, hi;
}
INTERVAL;
INTERVAL vmul(double, double, INTERVAL);
INTERVAL vdiv(double, double, INTERVAL);
int dcheck(INTERVAL);
double dreg[26];
INTERVAL vreg[26];
%}
%expect 18
%start line
%union
{
int ival;
double dval;
INTERVAL vval;
}
%token <ival> DREG VREG /* indices into dreg, vreg arrays */
%token <dval> CONST /* floating point constant */
%type <dval> dexp /* expression */
%type <vval> vexp /* interval expression */
/* precedence information about the operators */
%left '+' '-'
%left '*' '/'
%left UMINUS /* precedence for unary minus */
%% /* beginning of rules section */
lines : /* empty */
| lines line
;
line : dexp '\n'
{
(void) printf("%15.8f\n", $1);
}
| vexp '\n'
{
(void) printf("(%15.8f, %15.8f)\n", $1.lo, $1.hi);
}
| DREG '=' dexp '\n'
{
dreg[$1] = $3;
}
| VREG '=' vexp '\n'
{
vreg[$1] = $3;
}
| error '\n'
{
yyerrok;
}
;
dexp : CONST
| DREG
{
$$ = dreg[$1];
}
| dexp '+' dexp
{
$$ = $1 + $3;
}
| dexp '-' dexp
{
$$ = $1 - $3;
}
| dexp '*' dexp
{
$$ = $1 * $3;
}
| dexp '/' dexp
{
$$ = $1 / $3;
}
| '-' dexp %prec UMINUS
{
$$ = -$2;
}
| '(' dexp ')'
{
$$ = $2;
}
;
vexp : dexp
{
$$.hi = $$.lo = $1;
}
| '(' dexp ',' dexp ')'
{
$$.lo = $2;
$$.hi = $4;
if ( $$.lo > $$.hi )
{
(void) printf("interval out of order\n");
YYERROR;
}
}
| VREG
{
$$ = vreg[$1];
}
| vexp '+' vexp
{
$$.hi = $1.hi + $3.hi;
$$.lo = $1.lo + $3.lo;
}
| dexp '+' vexp
{
$$.hi = $1 + $3.hi;
$$.lo = $1 + $3.lo;
}
| vexp '-' vexp
{
$$.hi = $1.hi - $3.lo;
$$.lo = $1.lo - $3.hi;
}
| dexp '-' vexp
{
$$.hi = $1 - $3.lo;
$$.lo = $1 - $3.hi;
}
| vexp '*' vexp
{
$$ = vmul( $1.lo, $1.hi, $3 );
}
| dexp '*' vexp
{
$$ = vmul ($1, $1, $3 );
}
| vexp '/' vexp
{
if (dcheck($3)) YYERROR;
$$ = vdiv ( $1.lo, $1.hi, $3 );
}
| dexp '/' vexp
{
if (dcheck ( $3 )) YYERROR;
$$ = vdiv ($1, $1, $3 );
}
| '-' vexp %prec UMINUS
{
$$.hi = -$2.lo;
$$.lo = -$2.hi;
}
| '(' vexp ')'
{
$$ = $2;
}
;
%% /* beginning of subroutines section */
#ifdef YYBYACC
extern int YYLEX_DECL();
static void YYERROR_DECL();
#endif
#define BSZ 50 /* buffer size for floating point numbers */
/* lexical analysis */
static void
yyerror(const char *s)
{
fprintf(stderr, "%s\n", s);
}
int
yylex(void)
{
int c;
while ((c = getchar()) == ' ')
{ /* skip over blanks */
}
if (isupper(c))
{
yylval.ival = c - 'A';
return (VREG);
}
if (islower(c))
{
yylval.ival = c - 'a';
return (DREG);
}
if (isdigit(c) || c == '.')
{
/* gobble up digits, points, exponents */
char buf[BSZ + 1], *cp = buf;
int dot = 0, expr = 0;
for (; (cp - buf) < BSZ; ++cp, c = getchar())
{
*cp = c;
if (isdigit(c))
continue;
if (c == '.')
{
if (dot++ || expr)
return ('.'); /* will cause syntax error */
continue;
}
if (c == 'e')
{
if (expr++)
return ('e'); /* will cause syntax error */
continue;
}
/* end of number */
break;
}
*cp = '\0';
if ((cp - buf) >= BSZ)
printf("constant too long: truncated\n");
else
ungetc(c, stdin); /* push back last char read */
yylval.dval = atof(buf);
return (CONST);
}
return (c);
}
static INTERVAL
hilo(double a, double b, double c, double d)
{
/* returns the smallest interval containing a, b, c, and d */
/* used by *, / routines */
INTERVAL v;
if (a > b)
{
v.hi = a;
v.lo = b;
}
else
{
v.hi = b;
v.lo = a;
}
if (c > d)
{
if (c > v.hi)
v.hi = c;
if (d < v.lo)
v.lo = d;
}
else
{
if (d > v.hi)
v.hi = d;
if (c < v.lo)
v.lo = c;
}
return (v);
}
INTERVAL
vmul(double a, double b, INTERVAL v)
{
return (hilo(a * v.hi, a * v.lo, b * v.hi, b * v.lo));
}
int
dcheck(INTERVAL v)
{
if (v.hi >= 0. && v.lo <= 0.)
{
printf("divisor interval contains 0.\n");
return (1);
}
return (0);
}
INTERVAL
vdiv(double a, double b, INTERVAL v)
{
return (hilo(a / v.hi, a / v.lo, b / v.hi, b / v.lo));
}