%{
/* Written by Pace Willisson (pace@blitz.com) 
 * and placed in the public domain.
 *
 * Largely rewritten by J.T. Conklin (jtc@wimsey.com)
 *
 * $FreeBSD: src/bin/expr/expr.y,v 1.14.2.3 2001/08/01 02:37:46 obrien Exp $
 */

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <regex.h>
#include <limits.h>
  
#define yylex   expr_yylex

enum valtype {
        integer, numeric_string, string
} ;

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

static struct val *result;

int             chk_div (quad_t, quad_t);
int             chk_minus (quad_t, quad_t, quad_t);
int             chk_plus (quad_t, quad_t, quad_t);
int             chk_times (quad_t, quad_t, quad_t);
void            free_value (struct val *);
int             is_zero_or_null (struct val *);
int             isstring (struct val *);
int             main (int, char **);
struct val      *make_integer (quad_t);
struct val      *make_str (const char *);
struct val      *op_and (struct val *, struct val *);
struct val      *op_colon (struct val *, struct val *);
struct val      *op_div (struct val *, struct val *);
struct val      *op_eq (struct val *, struct val *);
struct val      *op_ge (struct val *, struct val *);
struct val      *op_gt (struct val *, struct val *);
struct val      *op_le (struct val *, struct val *);
struct val      *op_lt (struct val *, struct val *);
struct val      *op_minus (struct val *, struct val *);
struct val      *op_ne (struct val *, struct val *);
struct val      *op_or (struct val *, struct val *);
struct val      *op_plus (struct val *, struct val *);
struct val      *op_rem (struct val *, struct val *);
struct val      *op_times (struct val *, struct val *);
quad_t          to_integer (struct val *);
void            to_string (struct val *);
int             yyerror (const char *) __dead2;
static int      yylex (void);

static char **av;
%}

%union
{
        struct val *val;
}

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

%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(quad_t i)
{
        struct val *vp;

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

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

struct val *
make_str(const char *s)
{
        struct val *vp;
        size_t i;
        int isint;

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

        for(i = 1, isint = isdigit(s[0]) || s[0] == '-';
            isint && i < strlen(s);
            i++)
        {
                if(!isdigit(s[i]))
                         isint = 0;
        }

        if (isint)
                vp->type = numeric_string;
        else    
                vp->type = string;

        return vp;
}


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


quad_t
to_integer(struct val *vp)
{
        quad_t i;

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

        if (vp->type == string)
                return 0;

        /* vp->type == numeric_string, make it numeric */
        errno = 0;
        i  = strtoll(vp->u.s, NULL, 10);
        if (errno != 0) {
                errx (2, "overflow");
        }
        free (vp->u.s);
        vp->u.i = i;
        vp->type = integer;
        return 1;
}

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

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

        tmp = malloc ((size_t)25);
        if (tmp == NULL) {
                errx (2, "malloc() failed");
        }

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


int
isstring(struct val *vp)
{
        /* only TRUE if this string is not a valid integer */
        return (vp->type == string);
}


static int
yylex(void)
{
        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(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 */
}

static void
usage(void)
{
        fprintf(stderr,
                "usage: expr expression\n");
        exit(EXIT_FAILURE);
}

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

        if (argc > 1 && strcmp(argv[1], "--"))
                av = argv + 1;
        else if (argc > 2)
                av = argv + 2;
        else
                usage();

        yyparse ();

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

        return (is_zero_or_null (result));
}

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

int
chk_plus(quad_t a, quad_t b, quad_t r)
{
        /* sum of two positive numbers must be positive */
        if (a > 0 && b > 0 && r <= 0)
                return 1;
        /* sum of two negative numbers must be negative */
        if (a < 0 && b < 0 && r >= 0)
                return 1;
        /* all other cases are OK */
        return 0;
}

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

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

        r = make_integer (/*(quad_t)*/(a->u.i + b->u.i));
        if (chk_plus (a->u.i, b->u.i, r->u.i)) {
                errx (2, "overflow");
        }
        free_value (a);
        free_value (b);
        return r;
}

int
chk_minus(quad_t a, quad_t b, quad_t r)
{
        /* special case subtraction of QUAD_MIN */
        if (b == QUAD_MIN) {
                if (a >= 0)
                        return 1;
                else
                        return 0;
        }
        /* this is allowed for b != QUAD_MIN */
        return chk_plus (a, -b, r);
}

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

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

        r = make_integer (/*(quad_t)*/(a->u.i - b->u.i));
        if (chk_minus (a->u.i, b->u.i, r->u.i)) {
                errx (2, "overflow");
        }
        free_value (a);
        free_value (b);
        return r;
}

int
chk_times(quad_t a, quad_t b, quad_t r)
{
        /* special case: first operand is 0, no overflow possible */
        if (a == 0)
                return 0;
        /* cerify that result of division matches second operand */
        if (r / a != b)
                return 1;
        return 0;
}

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

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

        r = make_integer (/*(quad_t)*/(a->u.i * b->u.i));
        if (chk_times (a->u.i, b->u.i, r->u.i)) {
                errx (2, "overflow");
        }
        free_value (a);
        free_value (b);
        return (r);
}

int
chk_div(quad_t a, quad_t b)
{
        /* div by zero has been taken care of before */
        /* only QUAD_MIN / -1 causes overflow */
        if (a == QUAD_MIN && b == -1)
                return 1;
        /* everything else is OK */
        return 0;
}

struct val *
op_div(struct val *a, struct val *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 (/*(quad_t)*/(a->u.i / b->u.i));
        if (chk_div (a->u.i, b->u.i)) {
                errx (2, "overflow");
        }
        free_value (a);
        free_value (b);
        return r;
}
        
struct val *
op_rem(struct val *a, struct val *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 (/*(quad_t)*/(a->u.i % b->u.i));
        /* chk_rem necessary ??? */
        free_value (a);
        free_value (b);
        return r;
}
        
struct val *
op_colon(struct val *a, struct val *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, (size_t)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 ((quad_t)(rm[0].rm_eo - rm[0].rm_so));
                }
        } else {
                if (rp.re_nsub == 0) {
                        v = make_integer ((quad_t)0);
                } else {
                        v = make_str ("");
                }
        }

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

        return v;
}