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Diffstat (limited to 'contrib/byacc/test/calc1.y')
| -rw-r--r-- | contrib/byacc/test/calc1.y | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/contrib/byacc/test/calc1.y b/contrib/byacc/test/calc1.y new file mode 100644 index 0000000..1f42e1f --- /dev/null +++ b/contrib/byacc/test/calc1.y @@ -0,0 +1,305 @@ +%{ + +/* 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); + +extern int yylex(void); +static void yyerror(const char *s); + +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 */ + +#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 = (char) 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)); +} |
