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expr comments, cleanup, UTF-8 support

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This commit is contained in:
Evan Gates 2015-02-25 20:12:14 -08:00 committed by sin
parent 1cdb424ac6
commit bf4c5d1fcd
2 changed files with 143 additions and 140 deletions
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2
README
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@ -29,7 +29,7 @@ The following tools are implemented ('*' == finished, '#' == UTF-8 support,
=* echo yes none =* echo yes none
=* env yes none =* env yes none
#* expand yes none #* expand yes none
=* expr yes none #* expr yes none
=* false yes none =* false yes none
= find yes none = find yes none
#* fold yes none #* fold yes none

281
expr.c
View File

@ -1,31 +1,23 @@
/* See LICENSE file for copyright and license details. */ /* See LICENSE file for copyright and license details. */
#include <inttypes.h> #include <inttypes.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h>
#include <string.h> #include <string.h>
#include "utf.h"
#include "util.h" #include "util.h"
/* token types for lexing/parsing
* single character operators represent themselves */
enum { enum {
VAL = CHAR_MAX + 1, GE, LE, NE VAL = CHAR_MAX + 1, GE, LE, NE
}; };
typedef struct { typedef struct {
char *s; char *s; /* iff s is NULL, Val is an integer */
intmax_t n; intmax_t n;
} Val; } Val;
static void enan(Val);
static void ezero(intmax_t);
static void doop(int*, int**, Val*, Val**);
static Val match(Val, Val);
static int valcmp(Val, Val);
static char *valstr(Val, char *, size_t);
static int lex(char *);
static int parse(char **, int);
static size_t intlen; static size_t intlen;
static Val lastval;
static void static void
enan(Val v) enan(Val v)
@ -41,53 +33,117 @@ ezero(intmax_t n)
enprintf(2, "division by zero\n"); enprintf(2, "division by zero\n");
} }
static char *
valstr(Val val, char *buf, size_t bufsiz)
{
if (val.s)
return val.s;
snprintf(buf, bufsiz, "%"PRIdMAX, val.n);
return buf;
}
static int
valcmp(Val a, Val b)
{
char buf1[intlen], buf2[intlen];
char *astr = valstr(a, buf1, sizeof(buf1));
char *bstr = valstr(b, buf2, sizeof(buf2));
if (!a.s && !b.s)
return (a.n > b.n) - (a.n < b.n);
return strcmp(astr, bstr);
}
/* match vstr against BRE vregx (treat both values as strings)
* if there is at least one subexpression \(...\)
* then return the text matched by it \1 (empty string for no match)
* else return number of characters matched (0 for no match)
*/
static Val
match(Val vstr, Val vregx)
{
regex_t re;
regmatch_t matches[2];
char buf1[intlen], buf2[intlen];
char *str = valstr(vstr, buf1, sizeof(buf1));
char *regx = valstr(vregx, buf2, sizeof(buf2));;
char anchreg[strlen(regx) + 2];
/* expr(1p) "all patterns are anchored to the beginning of the string" */
snprintf(anchreg, sizeof(anchreg), "^%s", regx);
enregcomp(3, &re, anchreg, 0);
if (regexec(&re, str, 2, matches, 0)) {
regfree(&re);
return (Val){ (re.re_nsub ? "" : NULL), 0 };
}
if (re.re_nsub) {
intmax_t d;
char *s = str + matches[1].rm_so, *p = str + matches[1].rm_eo;
regfree(&re);
*p = '\0';
d = strtoimax(s, &p, 10);
if (*s && !*p) /* string matched by subexpression is an integer */
return (Val){ NULL, d };
/* FIXME? string is never free()d, worth fixing?
* need to allocate as it could be in buf1 instead of vstr.s */
return (Val){ enstrdup(3, s), 0 };
}
regfree(&re);
str += matches[0].rm_so;
return (Val){ NULL, utfnlen(str, matches[0].rm_eo - matches[0].rm_so) };
}
/* ops points to a stack of operators, opp points to one past the last op
* vals points to a stack of values , valp points to one past the last val
* guaranteed that opp != ops
* ops is unused here, but still included for parity with vals
* pop operator, pop two values, apply operator, push result
*/
static void static void
doop(int *op, int **opp, Val *val, Val **valp) doop(int *ops, int **opp, Val *vals, Val **valp)
{ {
Val ret, a, b; Val ret, a, b;
int o; int op;
/* For an operation, we need a valid operator /* For an operation, we need a valid operator
* and two values on the stack */ * and two values on the stack */
if ((*opp)[-1] == '(') if ((*opp)[-1] == '(')
enprintf(2, "syntax error: extra (\n"); enprintf(2, "syntax error: extra (\n");
if (*valp - val < 2) if (*valp - vals < 2)
enprintf(2, "syntax error: missing expression or extra operator\n"); enprintf(2, "syntax error: missing expression or extra operator\n");
a = (*valp)[-2]; a = (*valp)[-2];
b = (*valp)[-1]; b = (*valp)[-1];
o = (*opp)[-1]; op = (*opp)[-1];
switch (o) { switch (op) {
case '|': case '|':
if (a.s && *a.s) { if ( a.s && *a.s) ret = (Val){ a.s , 0 };
ret = (Val){ a.s, 0 }; else if (!a.s && a.n) ret = (Val){ NULL, a.n };
} else if (!a.s && a.n) { else if ( b.s && *b.s) ret = (Val){ b.s , 0 };
ret = (Val){ NULL, a.n }; else ret = (Val){ NULL, b.n };
} else if (b.s && *b.s) {
ret = (Val){ b.s, 0 };
} else {
ret = (Val){ NULL, b.n };
}
break; break;
case '&': case '&':
if (((a.s && *a.s) || a.n) && if (((a.s && *a.s) || a.n) && ((b.s && *b.s) || b.n))
((b.s && *b.s) || b.n)) {
ret = a; ret = a;
} else { else
ret = (Val){ NULL, 0 }; ret = (Val){ NULL, 0 };
}
break; break;
case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break; case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break;
case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break; case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break;
case GE: ret = (Val){ NULL, valcmp(a, b) >= 0 }; break; case GE : ret = (Val){ NULL, valcmp(a, b) >= 0 }; break;
case '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break; case '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break;
case LE: ret = (Val){ NULL, valcmp(a, b) <= 0 }; break; case LE : ret = (Val){ NULL, valcmp(a, b) <= 0 }; break;
case NE: ret = (Val){ NULL, valcmp(a, b) != 0 }; break; case NE : ret = (Val){ NULL, valcmp(a, b) != 0 }; break;
case '+': enan(a); enan(b); ret = (Val){ NULL, a.n + b.n }; break; case '+': enan(a); enan(b); ret = (Val){ NULL, a.n + b.n }; break;
case '-': enan(a); enan(b); ret = (Val){ NULL, a.n - b.n }; break; case '-': enan(a); enan(b); ret = (Val){ NULL, a.n - b.n }; break;
case '*': enan(a); enan(b); ret = (Val){ NULL, a.n * b.n }; break; case '*': enan(a); enan(b); ret = (Val){ NULL, a.n * b.n }; break;
case '/': enan(a); enan(b); ezero(b.n); ret = (Val){ NULL, a.n / b.n }; break; case '/': enan(a); enan(b); ezero(b.n); ret = (Val){ NULL, a.n / b.n }; break;
case '%': enan(a); enan(b); ezero(b.n); ret = (Val){ NULL, a.n % b.n }; break; case '%': enan(a); enan(b); ezero(b.n); ret = (Val){ NULL, a.n % b.n }; break;
@ -99,110 +155,50 @@ doop(int *op, int **opp, Val *val, Val **valp)
(*valp)--; (*valp)--;
} }
static Val /* retrn the type of the next token, s
match(Val vstr, Val vregx) * if it is a value, place the value in v for use by parser
*/
static int
lex(char *s, Val *v)
{ {
intmax_t d; intmax_t d;
char *anchreg, *ret, *p; char *p, *ops = "|&=><+-*/%():";
char buf1[intlen], buf2[intlen], *str, *regx;
regoff_t len;
regex_t re;
regmatch_t matches[2];
str = valstr(vstr, buf1, sizeof(buf1));
regx = valstr(vregx, buf2, sizeof(buf2));
anchreg = enmalloc(3, strlen(regx) + 2);
snprintf(anchreg, strlen(regx) + 2, "^%s", regx);
enregcomp(3, &re, anchreg, 0);
free(anchreg);
if (regexec(&re, str, 2, matches, 0)) {
regfree(&re);
return (Val){ (re.re_nsub ? "" : NULL), 0 };
}
if (re.re_nsub) {
regfree(&re);
len = matches[1].rm_eo - matches[1].rm_so + 1;
ret = enmalloc(3, len);
strlcpy(ret, str + matches[1].rm_so, len);
d = strtoimax(ret, &p, 10);
if (*ret && !*p) {
free(ret);
return (Val){ NULL, d };
}
return (Val){ ret, 0 };
}
regfree(&re);
return (Val){ NULL, matches[0].rm_eo - matches[0].rm_so };
}
static int
valcmp(Val a, Val b)
{
char buf1[intlen], buf2[intlen], *astr, *bstr;
astr = valstr(a, buf1, sizeof(buf1));
bstr = valstr(b, buf2, sizeof(buf2));
return strcmp(astr, bstr);
}
static char *
valstr(Val val, char *buf, size_t bufsiz)
{
if (val.s)
return val.s;
snprintf(buf, bufsiz, "%"PRIdMAX, val.n);
return buf;
}
static int
lex(char *p)
{
intmax_t d;
char *q, *ops = "|&=><+-*/%():";
/* clean integer */ /* clean integer */
d = strtoimax(p, &q, 10); d = strtoimax(s, &p, 10);
if (*p && !*q) { if (*s && !*p) {
lastval = (Val){ NULL, d }; *v = (Val){ NULL, d };
return VAL; return VAL;
} }
/* one-char operand */ /* one-char operand */
if (*p && !*(p + 1) && strchr(ops, *p)) if (*s && !s[1] && strchr(ops, *s))
return *p; return *s;
/* two-char operand */ /* two-char operand */
if (*p && *(p + 1) == '=' && !*(p + 2)) { if (!strcmp(s, ">=")) return GE;
switch (*p) { if (!strcmp(s, "<=")) return LE;
case '>': if (!strcmp(s, "!=")) return NE;
return GE;
case '<':
return LE;
case '!':
return NE;
}
}
/* nothing matched, treat as string */ /* nothing matched, treat as string */
lastval = (Val){ p, 0 }; *v = (Val){ s, 0 };
return VAL; return VAL;
} }
/* using shunting-yard to convert from infix to rpn
* https://en.wikipedia.org/wiki/Shunting-yard_algorithm
* instead of creating rpn output to evaluate later, evaluate it immediately as
* it is created
* vals is the value stack, valp points to one past last value on the stack
* ops is the operator stack, opp points to one past last op on the stack
*/
static int static int
parse(char **expr, int exprlen) parse(char **expr, int exprlen)
{ {
Val val[exprlen], *valp = val; Val vals[exprlen], *valp = vals;
int op[exprlen], *opp = op; int ops[exprlen], *opp = ops;
int i, type, lasttype = 0; int i, lasttype = 0;
char prec[] = { char prec[] = { /* precedence of operators */
[ 0 ] = 0, [VAL] = 0,
['|'] = 1, ['|'] = 1,
['&'] = 2, ['&'] = 2,
['='] = 3, ['>'] = 3, [GE] = 3, ['<'] = 3, [LE] = 3, [NE] = 3, ['='] = 3, ['>'] = 3, [GE] = 3, ['<'] = 3, [LE] = 3, [NE] = 3,
@ -212,11 +208,12 @@ parse(char **expr, int exprlen)
}; };
for (i = 0; i < exprlen; i++) { for (i = 0; i < exprlen; i++) {
type = lex(expr[i]); Val v;
int type = lex(expr[i], &v);
switch (type) { switch (type) {
case VAL: case VAL:
*valp++ = lastval; *valp++ = v;
break; break;
case '(': case '(':
*opp++ = '('; *opp++ = '(';
@ -224,31 +221,30 @@ parse(char **expr, int exprlen)
case ')': case ')':
if (lasttype == '(') if (lasttype == '(')
enprintf(2, "syntax error: empty ( )\n"); enprintf(2, "syntax error: empty ( )\n");
while (opp > op && opp[-1] != '(') while (opp > ops && opp[-1] != '(')
doop(op, &opp, val, &valp); doop(ops, &opp, vals, &valp);
if (opp == op) if (opp == ops)
enprintf(2, "syntax error: extra )\n"); enprintf(2, "syntax error: extra )\n");
opp--; opp--;
break; break;
default : default: /* operator */
if (prec[lasttype]) if (prec[lasttype])
enprintf(2, "syntax error: extra operator\n"); enprintf(2, "syntax error: extra operator\n");
while (opp > op && prec[opp[-1]] >= prec[type]) while (opp > ops && prec[opp[-1]] >= prec[type])
doop(op, &opp, val, &valp); doop(ops, &opp, vals, &valp);
*opp++ = type; *opp++ = type;
break; break;
} }
lasttype = type; lasttype = type;
} }
while (opp > op) while (opp > ops)
doop(op, &opp, val, &valp); doop(ops, &opp, vals, &valp);
if (valp == val) if (valp == vals)
enprintf(2, "syntax error: missing expression\n"); enprintf(2, "syntax error: missing expression\n");
if (valp - val > 1) if (--valp != vals)
enprintf(2, "syntax error: extra expression\n"); enprintf(2, "syntax error: extra expression\n");
valp--;
if (valp->s) if (valp->s)
printf("%s\n", valp->s); printf("%s\n", valp->s);
else else
@ -257,10 +253,17 @@ parse(char **expr, int exprlen)
return (valp->s && *valp->s) || valp->n; return (valp->s && *valp->s) || valp->n;
} }
/* the only way to get usage() is if the user didn't supply -- and expression
* begins with a -
* expr(1p): "... the conforming application must employ the -- construct ...
* if there is any chance the first operand might be a negative integer (or any
* string with a leading minus"
*/
static void static void
usage(void) usage(void)
{ {
eprintf("usage: %s expression\n", argv0); enprintf(3, "usage: %s [--] expression\n"
"note : the -- is mandatory if expression begins with a -\n", argv0);
} }
int int
@ -269,11 +272,11 @@ main(int argc, char *argv[])
intmax_t n = INTMAX_MIN; intmax_t n = INTMAX_MIN;
/* Get the maximum number of digits (+ sign) */ /* Get the maximum number of digits (+ sign) */
for (intlen = (n < 0); n; n /= 10, ++intlen); for (intlen = (n < 0); n; n /= 10, ++intlen)
;
ARGBEGIN { ARGBEGIN {
default: default: usage();
usage();
} ARGEND; } ARGEND;
return !parse(argv, argc); return !parse(argv, argc);