ref: 733c5d6645b133b60d304c38fcb1398f94d0618c
dir: /sys/src/ape/cmd/pdksh/expr.c/
/*
* Korn expression evaluation
*/
/*
* todo: better error handling: if in builtin, should be builtin error, etc.
*/
#include "sh.h"
#include <ctype.h>
/* The order of these enums is constrained by the order of opinfo[] */
enum token {
/* some (long) unary operators */
O_PLUSPLUS = 0, O_MINUSMINUS,
/* binary operators */
O_EQ, O_NE,
/* assignments are assumed to be in range O_ASN .. O_BORASN */
O_ASN, O_TIMESASN, O_DIVASN, O_MODASN, O_PLUSASN, O_MINUSASN,
O_LSHIFTASN, O_RSHIFTASN, O_BANDASN, O_BXORASN, O_BORASN,
O_LSHIFT, O_RSHIFT,
O_LE, O_GE, O_LT, O_GT,
O_LAND,
O_LOR,
O_TIMES, O_DIV, O_MOD,
O_PLUS, O_MINUS,
O_BAND,
O_BXOR,
O_BOR,
O_TERN,
O_COMMA,
/* things after this aren't used as binary operators */
/* unary that are not also binaries */
O_BNOT, O_LNOT,
/* misc */
OPEN_PAREN, CLOSE_PAREN, CTERN,
/* things that don't appear in the opinfo[] table */
VAR, LIT, END, BAD
};
#define IS_BINOP(op) (((int)op) >= (int)O_EQ && ((int)op) <= (int)O_COMMA)
#define IS_ASSIGNOP(op) ((int)(op) >= (int)O_ASN && (int)(op) <= (int)O_BORASN)
enum prec {
P_PRIMARY = 0, /* VAR, LIT, (), ~ ! - + */
P_MULT, /* * / % */
P_ADD, /* + - */
P_SHIFT, /* << >> */
P_RELATION, /* < <= > >= */
P_EQUALITY, /* == != */
P_BAND, /* & */
P_BXOR, /* ^ */
P_BOR, /* | */
P_LAND, /* && */
P_LOR, /* || */
P_TERN, /* ?: */
P_ASSIGN, /* = *= /= %= += -= <<= >>= &= ^= |= */
P_COMMA /* , */
};
#define MAX_PREC P_COMMA
struct opinfo {
char name[4];
int len; /* name length */
enum prec prec; /* precidence: lower is higher */
};
/* Tokens in this table must be ordered so the longest are first
* (eg, += before +). If you change something, change the order
* of enum token too.
*/
static const struct opinfo opinfo[] = {
{ "++", 2, P_PRIMARY }, /* before + */
{ "--", 2, P_PRIMARY }, /* before - */
{ "==", 2, P_EQUALITY }, /* before = */
{ "!=", 2, P_EQUALITY }, /* before ! */
{ "=", 1, P_ASSIGN }, /* keep assigns in a block */
{ "*=", 2, P_ASSIGN },
{ "/=", 2, P_ASSIGN },
{ "%=", 2, P_ASSIGN },
{ "+=", 2, P_ASSIGN },
{ "-=", 2, P_ASSIGN },
{ "<<=", 3, P_ASSIGN },
{ ">>=", 3, P_ASSIGN },
{ "&=", 2, P_ASSIGN },
{ "^=", 2, P_ASSIGN },
{ "|=", 2, P_ASSIGN },
{ "<<", 2, P_SHIFT },
{ ">>", 2, P_SHIFT },
{ "<=", 2, P_RELATION },
{ ">=", 2, P_RELATION },
{ "<", 1, P_RELATION },
{ ">", 1, P_RELATION },
{ "&&", 2, P_LAND },
{ "||", 2, P_LOR },
{ "*", 1, P_MULT },
{ "/", 1, P_MULT },
{ "%", 1, P_MULT },
{ "+", 1, P_ADD },
{ "-", 1, P_ADD },
{ "&", 1, P_BAND },
{ "^", 1, P_BXOR },
{ "|", 1, P_BOR },
{ "?", 1, P_TERN },
{ ",", 1, P_COMMA },
{ "~", 1, P_PRIMARY },
{ "!", 1, P_PRIMARY },
{ "(", 1, P_PRIMARY },
{ ")", 1, P_PRIMARY },
{ ":", 1, P_PRIMARY },
{ "", 0, P_PRIMARY } /* end of table */
};
typedef struct expr_state Expr_state;
struct expr_state {
const char *expression; /* expression being evaluated */
const char *tokp; /* lexical position */
enum token tok; /* token from token() */
int noassign; /* don't do assigns (for ?:,&&,||) */
struct tbl *val; /* value from token() */
struct tbl *evaling; /* variable that is being recursively
* expanded (EXPRINEVAL flag set)
*/
};
enum error_type { ET_UNEXPECTED, ET_BADLIT, ET_RECURSIVE,
ET_LVALUE, ET_RDONLY, ET_STR };
static void evalerr ARGS((Expr_state *es, enum error_type type,
const char *str)) GCC_FUNC_ATTR(noreturn);
static struct tbl *evalexpr ARGS((Expr_state *es, enum prec prec));
static void token ARGS((Expr_state *es));
static struct tbl *do_ppmm ARGS((Expr_state *es, enum token op,
struct tbl *vasn, bool_t is_prefix));
static void assign_check ARGS((Expr_state *es, enum token op,
struct tbl *vasn));
static struct tbl *tempvar ARGS((void));
static struct tbl *intvar ARGS((Expr_state *es, struct tbl *vp));
/*
* parse and evalute expression
*/
int
evaluate(const char *expr, long *rval, int error_ok)
{
struct tbl v;
int ret;
v.flag = DEFINED|INTEGER;
v.type = 0;
ret = v_evaluate(&v, expr, error_ok);
*rval = v.val.i;
return ret;
}
/*
* parse and evalute expression, storing result in vp.
*/
int
v_evaluate(struct tbl *vp, const char *expr, volatile int error_ok)
{
struct tbl *v;
Expr_state curstate;
Expr_state * const es = &curstate;
int i;
/* save state to allow recursive calls */
curstate.expression = curstate.tokp = expr;
curstate.noassign = 0;
curstate.evaling = (struct tbl *) 0;
newenv(E_ERRH);
i = ksh_sigsetjmp(e->jbuf, 0);
if (i) {
/* Clear EXPRINEVAL in of any variables we were playing with */
if (curstate.evaling)
curstate.evaling->flag &= ~EXPRINEVAL;
quitenv();
if (i == LAEXPR) {
if (error_ok == KSH_RETURN_ERROR)
return 0;
errorf(null);
}
unwind(i);
/*NOTREACHED*/
}
token(es);
#if 1 /* ifdef-out to disallow empty expressions to be treated as 0 */
if (es->tok == END) {
es->tok = LIT;
es->val = tempvar();
}
#endif /* 0 */
v = intvar(es, evalexpr(es, MAX_PREC));
if (es->tok != END)
evalerr(es, ET_UNEXPECTED, (char *) 0);
if (vp->flag & INTEGER)
setint_v(vp, v);
else
/* can fail if readony */
setstr(vp, str_val(v), error_ok);
quitenv();
return 1;
}
static void
evalerr(Expr_state *es, enum error_type type, const char *str)
{
char tbuf[2];
const char *s;
switch (type) {
case ET_UNEXPECTED:
switch (es->tok) {
case VAR:
s = es->val->name;
break;
case LIT:
s = str_val(es->val);
break;
case END:
s = "end of expression";
break;
case BAD:
tbuf[0] = *es->tokp;
tbuf[1] = '\0';
s = tbuf;
break;
default:
s = opinfo[(int)es->tok].name;
}
warningf(TRUE, "%s: unexpected `%s'", es->expression, s);
break;
case ET_BADLIT:
warningf(TRUE, "%s: bad number `%s'", es->expression, str);
break;
case ET_RECURSIVE:
warningf(TRUE, "%s: expression recurses on parameter `%s'",
es->expression, str);
break;
case ET_LVALUE:
warningf(TRUE, "%s: %s requires lvalue",
es->expression, str);
break;
case ET_RDONLY:
warningf(TRUE, "%s: %s applied to read only variable",
es->expression, str);
break;
default: /* keep gcc happy */
case ET_STR:
warningf(TRUE, "%s: %s", es->expression, str);
break;
}
unwind(LAEXPR);
}
static struct tbl *
evalexpr(Expr_state *es, enum prec prec)
{
struct tbl *vl, UNINITIALIZED(*vr), *vasn;
enum token op;
long UNINITIALIZED(res);
if (prec == P_PRIMARY) {
op = es->tok;
if (op == O_BNOT || op == O_LNOT || op == O_MINUS
|| op == O_PLUS)
{
token(es);
vl = intvar(es, evalexpr(es, P_PRIMARY));
if (op == O_BNOT)
vl->val.i = ~vl->val.i;
else if (op == O_LNOT)
vl->val.i = !vl->val.i;
else if (op == O_MINUS)
vl->val.i = -vl->val.i;
/* op == O_PLUS is a no-op */
} else if (op == OPEN_PAREN) {
token(es);
vl = evalexpr(es, MAX_PREC);
if (es->tok != CLOSE_PAREN)
evalerr(es, ET_STR, "missing )");
token(es);
} else if (op == O_PLUSPLUS || op == O_MINUSMINUS) {
token(es);
vl = do_ppmm(es, op, es->val, TRUE);
token(es);
} else if (op == VAR || op == LIT) {
vl = es->val;
token(es);
} else {
evalerr(es, ET_UNEXPECTED, (char *) 0);
/*NOTREACHED*/
}
if (es->tok == O_PLUSPLUS || es->tok == O_MINUSMINUS) {
vl = do_ppmm(es, es->tok, vl, FALSE);
token(es);
}
return vl;
}
vl = evalexpr(es, ((int) prec) - 1);
for (op = es->tok; IS_BINOP(op) && opinfo[(int) op].prec == prec;
op = es->tok)
{
token(es);
vasn = vl;
if (op != O_ASN) /* vl may not have a value yet */
vl = intvar(es, vl);
if (IS_ASSIGNOP(op)) {
assign_check(es, op, vasn);
vr = intvar(es, evalexpr(es, P_ASSIGN));
} else if (op != O_TERN && op != O_LAND && op != O_LOR)
vr = intvar(es, evalexpr(es, ((int) prec) - 1));
if ((op == O_DIV || op == O_MOD || op == O_DIVASN
|| op == O_MODASN) && vr->val.i == 0)
{
if (es->noassign)
vr->val.i = 1;
else
evalerr(es, ET_STR, "zero divisor");
}
switch ((int) op) {
case O_TIMES:
case O_TIMESASN:
res = vl->val.i * vr->val.i;
break;
case O_DIV:
case O_DIVASN:
res = vl->val.i / vr->val.i;
break;
case O_MOD:
case O_MODASN:
res = vl->val.i % vr->val.i;
break;
case O_PLUS:
case O_PLUSASN:
res = vl->val.i + vr->val.i;
break;
case O_MINUS:
case O_MINUSASN:
res = vl->val.i - vr->val.i;
break;
case O_LSHIFT:
case O_LSHIFTASN:
res = vl->val.i << vr->val.i;
break;
case O_RSHIFT:
case O_RSHIFTASN:
res = vl->val.i >> vr->val.i;
break;
case O_LT:
res = vl->val.i < vr->val.i;
break;
case O_LE:
res = vl->val.i <= vr->val.i;
break;
case O_GT:
res = vl->val.i > vr->val.i;
break;
case O_GE:
res = vl->val.i >= vr->val.i;
break;
case O_EQ:
res = vl->val.i == vr->val.i;
break;
case O_NE:
res = vl->val.i != vr->val.i;
break;
case O_BAND:
case O_BANDASN:
res = vl->val.i & vr->val.i;
break;
case O_BXOR:
case O_BXORASN:
res = vl->val.i ^ vr->val.i;
break;
case O_BOR:
case O_BORASN:
res = vl->val.i | vr->val.i;
break;
case O_LAND:
if (!vl->val.i)
es->noassign++;
vr = intvar(es, evalexpr(es, ((int) prec) - 1));
res = vl->val.i && vr->val.i;
if (!vl->val.i)
es->noassign--;
break;
case O_LOR:
if (vl->val.i)
es->noassign++;
vr = intvar(es, evalexpr(es, ((int) prec) - 1));
res = vl->val.i || vr->val.i;
if (vl->val.i)
es->noassign--;
break;
case O_TERN:
{
int e = vl->val.i != 0;
if (!e)
es->noassign++;
vl = evalexpr(es, MAX_PREC);
if (!e)
es->noassign--;
if (es->tok != CTERN)
evalerr(es, ET_STR, "missing :");
token(es);
if (e)
es->noassign++;
vr = evalexpr(es, P_TERN);
if (e)
es->noassign--;
vl = e ? vl : vr;
}
break;
case O_ASN:
res = vr->val.i;
break;
case O_COMMA:
res = vr->val.i;
break;
}
if (IS_ASSIGNOP(op)) {
vr->val.i = res;
if (vasn->flag & INTEGER)
setint_v(vasn, vr);
else
setint(vasn, res);
vl = vr;
} else if (op != O_TERN)
vl->val.i = res;
}
return vl;
}
static void
token(Expr_state *es)
{
const char *cp;
int c;
char *tvar;
/* skip white space */
for (cp = es->tokp; (c = *cp), isspace(c); cp++)
;
es->tokp = cp;
if (c == '\0')
es->tok = END;
else if (letter(c)) {
for (; letnum(c); c = *cp)
cp++;
if (c == '[') {
int len;
len = array_ref_len(cp);
if (len == 0)
evalerr(es, ET_STR, "missing ]");
cp += len;
}
#ifdef KSH
else if (c == '(' /*)*/ ) {
/* todo: add math functions (all take single argument):
* abs acos asin atan cos cosh exp int log sin sinh sqrt
* tan tanh
*/
;
}
#endif /* KSH */
if (es->noassign) {
es->val = tempvar();
es->val->flag |= EXPRLVALUE;
} else {
tvar = str_nsave(es->tokp, cp - es->tokp, ATEMP);
es->val = global(tvar);
afree(tvar, ATEMP);
}
es->tok = VAR;
} else if (digit(c)) {
for (; c != '_' && (letnum(c) || c == '#'); c = *cp++)
;
tvar = str_nsave(es->tokp, --cp - es->tokp, ATEMP);
es->val = tempvar();
es->val->flag &= ~INTEGER;
es->val->type = 0;
es->val->val.s = tvar;
if (setint_v(es->val, es->val) == NULL)
evalerr(es, ET_BADLIT, tvar);
afree(tvar, ATEMP);
es->tok = LIT;
} else {
int i, n0;
for (i = 0; (n0 = opinfo[i].name[0]); i++)
if (c == n0
&& strncmp(cp, opinfo[i].name, opinfo[i].len) == 0)
{
es->tok = (enum token) i;
cp += opinfo[i].len;
break;
}
if (!n0)
es->tok = BAD;
}
es->tokp = cp;
}
/* Do a ++ or -- operation */
static struct tbl *
do_ppmm(Expr_state *es, enum token op, struct tbl *vasn, bool_t is_prefix)
{
struct tbl *vl;
int oval;
assign_check(es, op, vasn);
vl = intvar(es, vasn);
oval = op == O_PLUSPLUS ? vl->val.i++ : vl->val.i--;
if (vasn->flag & INTEGER)
setint_v(vasn, vl);
else
setint(vasn, vl->val.i);
if (!is_prefix) /* undo the inc/dec */
vl->val.i = oval;
return vl;
}
static void
assign_check(Expr_state *es, enum token op, struct tbl *vasn)
{
if (vasn->name[0] == '\0' && !(vasn->flag & EXPRLVALUE))
evalerr(es, ET_LVALUE, opinfo[(int) op].name);
else if (vasn->flag & RDONLY)
evalerr(es, ET_RDONLY, opinfo[(int) op].name);
}
static struct tbl *
tempvar(void)
{
register struct tbl *vp;
vp = (struct tbl*) alloc(sizeof(struct tbl), ATEMP);
vp->flag = ISSET|INTEGER;
vp->type = 0;
vp->areap = ATEMP;
vp->val.i = 0;
vp->name[0] = '\0';
return vp;
}
/* cast (string) variable to temporary integer variable */
static struct tbl *
intvar(Expr_state *es, struct tbl *vp)
{
struct tbl *vq;
/* try to avoid replacing a temp var with another temp var */
if (vp->name[0] == '\0'
&& (vp->flag & (ISSET|INTEGER|EXPRLVALUE)) == (ISSET|INTEGER))
return vp;
vq = tempvar();
if (setint_v(vq, vp) == NULL) {
if (vp->flag & EXPRINEVAL)
evalerr(es, ET_RECURSIVE, vp->name);
es->evaling = vp;
vp->flag |= EXPRINEVAL;
v_evaluate(vq, str_val(vp), KSH_UNWIND_ERROR);
vp->flag &= ~EXPRINEVAL;
es->evaling = (struct tbl *) 0;
}
return vq;
}