freebsd-dev/bin/expr/expr.y
2011-07-09 12:20:15 +00:00

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%{
/*-
* Written by Pace Willisson (pace@blitz.com)
* and placed in the public domain.
*
* Largely rewritten by J.T. Conklin (jtc@wimsey.com)
*
* $FreeBSD$
*/
#include <sys/types.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <regex.h>
#include <unistd.h>
/*
* POSIX specifies a specific error code for syntax errors. We exit
* with this code for all errors.
*/
#define ERR_EXIT 2
enum valtype {
integer, numeric_string, string
} ;
struct val {
enum valtype type;
union {
char *s;
intmax_t i;
} u;
} ;
char **av;
int nonposix;
struct val *result;
void assert_to_integer(struct val *);
void assert_div(intmax_t, intmax_t);
void assert_minus(intmax_t, intmax_t, intmax_t);
void assert_plus(intmax_t, intmax_t, intmax_t);
void assert_times(intmax_t, intmax_t, intmax_t);
int compare_vals(struct val *, struct val *);
void free_value(struct val *);
int is_integer(const char *);
int is_string(struct val *);
int is_zero_or_null(struct val *);
struct val *make_integer(intmax_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 *);
int to_integer(struct val *);
void to_string(struct val *);
int yyerror(const char *);
int yylex(void);
int yyparse(void);
%}
%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(intmax_t i)
{
struct val *vp;
vp = (struct val *)malloc(sizeof(*vp));
if (vp == NULL)
errx(ERR_EXIT, "malloc() failed");
vp->type = integer;
vp->u.i = i;
return (vp);
}
struct val *
make_str(const char *s)
{
struct val *vp;
vp = (struct val *)malloc(sizeof(*vp));
if (vp == NULL || ((vp->u.s = strdup(s)) == NULL))
errx(ERR_EXIT, "malloc() failed");
if (is_integer(s))
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);
}
int
to_integer(struct val *vp)
{
intmax_t i;
/* we can only convert numeric_string to integer, here */
if (vp->type == numeric_string) {
errno = 0;
i = strtoimax(vp->u.s, (char **)NULL, 10);
/* just keep as numeric_string, if the conversion fails */
if (errno != ERANGE) {
free(vp->u.s);
vp->u.i = i;
vp->type = integer;
}
}
return (vp->type == integer);
}
void
assert_to_integer(struct val *vp)
{
if (vp->type == string)
errx(ERR_EXIT, "not a decimal number: '%s'", vp->u.s);
if (!to_integer(vp))
errx(ERR_EXIT, "operand too large: '%s'", vp->u.s);
}
void
to_string(struct val *vp)
{
char *tmp;
if (vp->type == string || vp->type == numeric_string)
return;
/*
* log_10(x) ~= 0.3 * log_2(x). Rounding up gives the number
* of digits; add one each for the sign and terminating null
* character, respectively.
*/
#define NDIGITS(x) (3 * (sizeof(x) * CHAR_BIT) / 10 + 1 + 1 + 1)
tmp = malloc(NDIGITS(vp->u.i));
if (tmp == NULL)
errx(ERR_EXIT, "malloc() failed");
sprintf(tmp, "%jd", vp->u.i);
vp->type = string;
vp->u.s = tmp;
}
int
is_integer(const char *s)
{
if (nonposix) {
if (*s == '\0')
return (1);
while (isspace((unsigned char)*s))
s++;
}
if (*s == '-' || (nonposix && *s == '+'))
s++;
if (*s == '\0')
return (0);
while (isdigit((unsigned char)*s))
s++;
return (*s == '\0');
}
int
is_string(struct val *vp)
{
/* only TRUE if this string is not a valid integer */
return (vp->type == string);
}
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);
return (*vp->u.s == 0 || (to_integer(vp) && vp->u.i == 0));
}
int
main(int argc, char *argv[])
{
int c;
setlocale(LC_ALL, "");
if (getenv("EXPR_COMPAT") != NULL
|| check_utility_compat("expr")) {
av = argv + 1;
nonposix = 1;
} else {
while ((c = getopt(argc, argv, "e")) != -1) {
switch (c) {
case 'e':
nonposix = 1;
break;
default:
errx(ERR_EXIT,
"usage: expr [-e] expression\n");
}
}
av = argv + optind;
}
yyparse();
if (result->type == integer)
printf("%jd\n", result->u.i);
else
printf("%s\n", result->u.s);
return (is_zero_or_null(result));
}
int
yyerror(const char *s __unused)
{
errx(ERR_EXIT, "syntax error");
}
struct val *
op_or(struct val *a, struct val *b)
{
if (!is_zero_or_null(a)) {
free_value(b);
return (a);
}
free_value(a);
if (!is_zero_or_null(b))
return (b);
free_value(b);
return (make_integer((intmax_t)0));
}
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((intmax_t)0));
} else {
free_value(b);
return (a);
}
}
int
compare_vals(struct val *a, struct val *b)
{
int r;
if (is_string(a) || is_string(b)) {
to_string(a);
to_string(b);
r = strcoll(a->u.s, b->u.s);
} else {
assert_to_integer(a);
assert_to_integer(b);
if (a->u.i > b->u.i)
r = 1;
else if (a->u.i < b->u.i)
r = -1;
else
r = 0;
}
free_value(a);
free_value(b);
return (r);
}
struct val *
op_eq(struct val *a, struct val *b)
{
return (make_integer((intmax_t)(compare_vals(a, b) == 0)));
}
struct val *
op_gt(struct val *a, struct val *b)
{
return (make_integer((intmax_t)(compare_vals(a, b) > 0)));
}
struct val *
op_lt(struct val *a, struct val *b)
{
return (make_integer((intmax_t)(compare_vals(a, b) < 0)));
}
struct val *
op_ge(struct val *a, struct val *b)
{
return (make_integer((intmax_t)(compare_vals(a, b) >= 0)));
}
struct val *
op_le(struct val *a, struct val *b)
{
return (make_integer((intmax_t)(compare_vals(a, b) <= 0)));
}
struct val *
op_ne(struct val *a, struct val *b)
{
return (make_integer((intmax_t)(compare_vals(a, b) != 0)));
}
void
assert_plus(intmax_t a, intmax_t b, intmax_t r)
{
/*
* sum of two positive numbers must be positive,
* sum of two negative numbers must be negative
*/
if ((a > 0 && b > 0 && r <= 0) ||
(a < 0 && b < 0 && r >= 0))
errx(ERR_EXIT, "overflow");
}
struct val *
op_plus(struct val *a, struct val *b)
{
struct val *r;
assert_to_integer(a);
assert_to_integer(b);
r = make_integer(a->u.i + b->u.i);
assert_plus(a->u.i, b->u.i, r->u.i);
free_value(a);
free_value(b);
return (r);
}
void
assert_minus(intmax_t a, intmax_t b, intmax_t r)
{
/* special case subtraction of INTMAX_MIN */
if (b == INTMAX_MIN && a < 0)
errx(ERR_EXIT, "overflow");
/* check addition of negative subtrahend */
assert_plus(a, -b, r);
}
struct val *
op_minus(struct val *a, struct val *b)
{
struct val *r;
assert_to_integer(a);
assert_to_integer(b);
r = make_integer(a->u.i - b->u.i);
assert_minus(a->u.i, b->u.i, r->u.i);
free_value(a);
free_value(b);
return (r);
}
void
assert_times(intmax_t a, intmax_t b, intmax_t r)
{
/*
* if first operand is 0, no overflow is possible,
* else result of division test must match second operand
*/
if (a != 0 && r / a != b)
errx(ERR_EXIT, "overflow");
}
struct val *
op_times(struct val *a, struct val *b)
{
struct val *r;
assert_to_integer(a);
assert_to_integer(b);
r = make_integer(a->u.i * b->u.i);
assert_times(a->u.i, b->u.i, r->u.i);
free_value(a);
free_value(b);
return (r);
}
void
assert_div(intmax_t a, intmax_t b)
{
if (b == 0)
errx(ERR_EXIT, "division by zero");
/* only INTMAX_MIN / -1 causes overflow */
if (a == INTMAX_MIN && b == -1)
errx(ERR_EXIT, "overflow");
}
struct val *
op_div(struct val *a, struct val *b)
{
struct val *r;
assert_to_integer(a);
assert_to_integer(b);
/* assert based on operands only, not on result */
assert_div(a->u.i, b->u.i);
r = make_integer(a->u.i / b->u.i);
free_value(a);
free_value(b);
return (r);
}
struct val *
op_rem(struct val *a, struct val *b)
{
struct val *r;
assert_to_integer(a);
assert_to_integer(b);
/* pass a=1 to only check for div by zero */
assert_div(1, b->u.i);
r = make_integer(a->u.i % b->u.i);
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 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(ERR_EXIT, "%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((intmax_t)(rm[0].rm_eo - rm[0].rm_so));
else
if (rp.re_nsub == 0)
v = make_integer((intmax_t)0);
else
v = make_str("");
/* free arguments and pattern buffer */
free_value(a);
free_value(b);
regfree(&rp);
return (v);
}