bin/expr/expr.y

%{
/* Written by Pace Willisson (pace@blitz.com)
 * and placed in the public domain.
 *
 * Largely rewritten by J.T. Conklin (jtc@wimsey.com)
 *
 * $Id : /b/source/CVS/src/bin/expr/expr.y,v 1.11 1993/08/17 16:01:23 jtc Exp $
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>
#include <ctype.h>
#include <err.h>

enum valtype {
        integer, string
} ;

struct val {
        enum valtype type;
        union {
                char *s;
                int   i;
        } u;
} ;

struct val *result;
struct val *op_or ();
struct val *op_and ();
struct val *op_eq ();
struct val *op_gt ();
struct val *op_lt ();
struct val *op_ge ();
struct val *op_le ();
struct val *op_ne ();
struct val *op_plus ();
struct val *op_minus ();
struct val *op_times ();
struct val *op_div ();
struct val *op_rem ();
struct val *op_colon ();

char **av;
%}

%union
{
        struct val *val;
}

%left <val> '|'
%left <val> '&'
%left <val> '=' '>' '<' GE LE NE
%left <val> '+' '-'
%left <val> '*' '/' '%'
%left <val> ':'
%left UNARY

%token <val> TOKEN
%type <val> start expr

%%

start: expr { result = $$; }

expr:   TOKEN
        | '(' expr ')' { $$ = $2; }
        | expr '|' expr { $$ = op_or ($1, $3); }
        | expr '&' expr { $$ = op_and ($1, $3); }
        | expr '=' expr { $$ = op_eq ($1, $3); }
        | expr '>' expr { $$ = op_gt ($1, $3); }
        | expr '<' expr { $$ = op_lt ($1, $3); }
        | expr GE expr  { $$ = op_ge ($1, $3); }
        | expr LE expr  { $$ = op_le ($1, $3); }
        | expr NE expr  { $$ = op_ne ($1, $3); }
        | expr '+' expr { $$ = op_plus ($1, $3); }
        | expr '-' expr { $$ = op_minus ($1, $3); }
        | expr '*' expr { $$ = op_times ($1, $3); }
        | expr '/' expr { $$ = op_div ($1, $3); }
        | expr '%' expr { $$ = op_rem ($1, $3); }
        | expr ':' expr { $$ = op_colon ($1, $3); }
        ;


%%

struct val *
make_integer (i)
int i;
{
        struct val *vp;

        vp = (struct val *) malloc (sizeof (*vp));
        if (vp == NULL) {
                err (2, NULL);
        }

        vp->type = integer;
        vp->u.i  = i;
        return vp;
}

struct val *
make_str (s)
char *s;
{
        struct val *vp;

        vp = (struct val *) malloc (sizeof (*vp));
        if (vp == NULL || ((vp->u.s = strdup (s)) == NULL)) {
                err (2, NULL);
        }

        vp->type = string;
        return vp;
}


void
free_value (vp)
struct val *vp;
{
        if (vp->type == string)
                free (vp->u.s);
}


int
to_integer (vp)
struct val *vp;
{
        char *s;
        int neg;
        int i;

        if (vp->type == integer)
                return 1;

        s = vp->u.s;
        i = 0;

        neg = (*s == '-');
        if (neg)
                s++;

        for (;*s; s++) {
                if (!isdigit (*s))
                        return 0;

                i *= 10;
                i += *s - '0';
        }

        free (vp->u.s);
        if (neg)
                i *= -1;

        vp->type = integer;
        vp->u.i  = i;
        return 1;
}

void
to_string (vp)
struct val *vp;
{
        char *tmp;

        if (vp->type == string)
                return;

        tmp = malloc (25);
        if (tmp == NULL) {
                err (2, NULL);
        }

        sprintf (tmp, "%d", vp->u.i);
        vp->type = string;
        vp->u.s  = tmp;
}


int
isstring (vp)
struct val *vp;
{
        return (vp->type == string);
}


int
yylex ()
{
        struct val *vp;
        char *p;

        if (*av == NULL)
                return (0);

        p = *av++;

        if (strlen (p) == 1) {
                if (strchr ("|&=<>+-*/%:()", *p))
                        return (*p);
        } else if (strlen (p) == 2 && p[1] == '=') {
                switch (*p) {
                case '>': return (GE);
                case '<': return (LE);
                case '!': return (NE);
                }
        }

        yylval.val = make_str (p);
        return (TOKEN);
}

int
is_zero_or_null (vp)
struct val *vp;
{
        if (vp->type == integer) {
                return (vp->u.i == 0);
        } else {
                return (*vp->u.s == 0 || (to_integer (vp) && vp->u.i == 0));
        }
        /* NOTREACHED */
}

void
main (argc, argv)
int argc;
char **argv;
{
        setlocale (LC_ALL, "");

        av = argv + 1;

        yyparse ();

        if (result->type == integer)
                printf ("%d\n", result->u.i);
        else
                printf ("%s\n", result->u.s);

        exit (is_zero_or_null (result));
}

int
yyerror (s)
char *s;
{
        errx (2, "syntax error");
}


struct val *
op_or (a, b)
struct val *a, *b;
{
        if (is_zero_or_null (a)) {
                free_value (a);
                return (b);
        } else {
                free_value (b);
                return (a);
        }
}

struct val *
op_and (a, b)
struct val *a, *b;
{
        if (is_zero_or_null (a) || is_zero_or_null (b)) {
                free_value (a);
                free_value (b);
                return (make_integer (0));
        } else {
                free_value (b);
                return (a);
        }
}

struct val *
op_eq (a, b)
struct val *a, *b;
{
        struct val *r;

        if (isstring (a) || isstring (b)) {
                to_string (a);
                to_string (b);
                r = make_integer (strcoll (a->u.s, b->u.s) == 0);
        } else {
                r = make_integer (a->u.i == b->u.i);
        }

        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_gt (a, b)
struct val *a, *b;
{
        struct val *r;

        if (isstring (a) || isstring (b)) {
                to_string (a);
                to_string (b);
                r = make_integer (strcoll (a->u.s, b->u.s) > 0);
        } else {
                r= make_integer (a->u.i > b->u.i);
        }

        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_lt (a, b)
struct val *a, *b;
{
        struct val *r;

        if (isstring (a) || isstring (b)) {
                to_string (a);
                to_string (b);
                r = make_integer (strcoll (a->u.s, b->u.s) < 0);
        } else {
                r = make_integer (a->u.i < b->u.i);
        }

        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_ge (a, b)
struct val *a, *b;
{
        struct val *r;

        if (isstring (a) || isstring (b)) {
                to_string (a);
                to_string (b);
                r = make_integer (strcoll (a->u.s, b->u.s) >= 0);
        } else {
                r = make_integer (a->u.i >= b->u.i);
        }

        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_le (a, b)
struct val *a, *b;
{
        struct val *r;

        if (isstring (a) || isstring (b)) {
                to_string (a);
                to_string (b);
                r = make_integer (strcoll (a->u.s, b->u.s) <= 0);
        } else {
                r = make_integer (a->u.i <= b->u.i);
        }

        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_ne (a, b)
struct val *a, *b;
{
        struct val *r;

        if (isstring (a) || isstring (b)) {
                to_string (a);
                to_string (b);
                r = make_integer (strcoll (a->u.s, b->u.s) != 0);
        } else {
                r = make_integer (a->u.i != b->u.i);
        }

        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_plus (a, b)
struct val *a, *b;
{
        struct val *r;

        if (!to_integer (a) || !to_integer (b)) {
                errx (2, "non-numeric argument");
        }

        r = make_integer (a->u.i + b->u.i);
        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_minus (a, b)
struct val *a, *b;
{
        struct val *r;

        if (!to_integer (a) || !to_integer (b)) {
                errx (2, "non-numeric argument");
        }

        r = make_integer (a->u.i - b->u.i);
        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_times (a, b)
struct val *a, *b;
{
        struct val *r;

        if (!to_integer (a) || !to_integer (b)) {
                errx (2, "non-numeric argument");
        }

        r = make_integer (a->u.i * b->u.i);
        free_value (a);
        free_value (b);
        return (r);
}

struct val *
op_div (a, b)
struct val *a, *b;
{
        struct val *r;

        if (!to_integer (a) || !to_integer (b)) {
                errx (2, "non-numeric argument");
        }

        if (b->u.i == 0) {
                errx (2, "division by zero");
        }

        r = make_integer (a->u.i / b->u.i);
        free_value (a);
        free_value (b);
        return r;
}

struct val *
op_rem (a, b)
struct val *a, *b;
{
        struct val *r;

        if (!to_integer (a) || !to_integer (b)) {
                errx (2, "non-numeric argument");
        }

        if (b->u.i == 0) {
                errx (2, "division by zero");
        }

        r = make_integer (a->u.i % b->u.i);
        free_value (a);
        free_value (b);
        return r;
}

#include <regex.h>

struct val *
op_colon (a, b)
struct val *a, *b;
{
        regex_t rp;
        regmatch_t rm[2];
        char errbuf[256];
        int eval;
        struct val *v;

        /* coerce to both arguments to strings */
        to_string(a);
        to_string(b);

        /* compile regular expression */
        if ((eval = regcomp (&rp, b->u.s, 0)) != 0) {
                regerror (eval, &rp, errbuf, sizeof(errbuf));
                errx (2, "%s", errbuf);
        }

        /* compare string against pattern */
        /* remember that patterns are anchored to the beginning of the line */
        if (regexec(&rp, a->u.s, 2, rm, 0) == 0 && rm[0].rm_so == 0) {
                if (rm[1].rm_so >= 0) {
                        *(a->u.s + rm[1].rm_eo) = '\0';
                        v = make_str (a->u.s + rm[1].rm_so);

                } else {
                        v = make_integer (rm[0].rm_eo - rm[0].rm_so);
                }
        } else {
                if (rp.re_nsub == 0) {
                        v = make_integer (0);
                } else {
                        v = make_str ("");
                }
        }

        /* free arguments and pattern buffer */
        free_value (a);
        free_value (b);
        regfree (&rp);

        return v;
}