Simplify type coercion in condition evaluation
Change nstr_mkselval() to generate values with promoted types only, and replace nstr_coerce_val() by new and simpler nstr_optype() in nstr_comp(). Replace the only remaining use of nstr_coerce_val() in surv() by nstr_promote(), and remove nstr_coerce_val(). This loses one half of the unimplemented sketch of coercions to NSC_STRING. Drop the other half from nstr_exec_val().
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4 changed files with 36 additions and 90 deletions
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@ -48,7 +48,7 @@ enum nsc_type {
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/* promoted types */
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NSC_LONG, /* long */
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NSC_DOUBLE, /* double */
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NSC_STRING, /* char *, zero-terminated string */
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NSC_STRING, /* character string */
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/* unpromoted types */
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NSC_CHAR, /* signed char */
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NSC_UCHAR, /* unsigned char */
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@ -61,7 +61,7 @@ enum nsc_type {
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may need hiding */
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NSC_TIME, /* time_t */
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NSC_FLOAT, /* float */
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NSC_STRINGY, /* char[], may be zero-terminated */
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NSC_STRINGY, /* char[] */
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/* aliases, must match typedefs */
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NSC_NATID = NSC_UCHAR /* nation id */
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};
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@ -287,7 +287,6 @@ extern struct symbol sector_navigation[];
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/* src/lib/subs/nstr.c */
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extern int nstr_comp(struct nscstr *np, int len, int type, char *str);
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extern char *nstr_comp_val(char *, struct valstr*, int);
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extern int nstr_coerce_val(struct valstr *, enum nsc_type, char *);
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extern int nstr_exec(struct nscstr *, int, void *);
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/* src/lib/common/nstreval.c */
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extern struct valstr *nstr_mksymval(struct valstr *, struct castr *, int);
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@ -71,7 +71,7 @@ surv(void)
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ptr = nstr_comp_val(ptr, &val, EF_SECTOR);
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if (!ptr)
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return RET_SYN;
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if (val.val_cat != NSC_OFF || nstr_coerce_val(&val, NSC_LONG, NULL) < 0) {
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if (val.val_cat != NSC_OFF || nstr_promote(val.val_type) != NSC_LONG) {
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pr("Can't survey this\n");
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return RET_SYN;
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}
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@ -66,8 +66,7 @@ nstr_mksymval(struct valstr *val, struct castr *ca, int idx)
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* PTR points to a context object of the type that was used to compile
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* the value.
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* Unless WANT is NSC_NOTYPE, coerce the value to promoted value type
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* WANT. VAL must be coercible. That's the case if a previous
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* nstr_coerce_val(VAL, WANT, STR) succeeded.
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* WANT. VAL must be coercible.
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*/
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struct valstr *
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nstr_exec_val(struct valstr *val, natid cnum, void *ptr, enum nsc_type want)
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@ -186,6 +185,7 @@ nstr_exec_val(struct valstr *val, natid cnum, void *ptr, enum nsc_type want)
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valtype = NSC_NOTYPE;
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}
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/* coerce */
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if (valtype == want)
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;
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else if (want == NSC_DOUBLE) {
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@ -193,8 +193,7 @@ nstr_exec_val(struct valstr *val, natid cnum, void *ptr, enum nsc_type want)
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valtype = want;
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val->val_as.dbl = val->val_as.lng;
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}
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} else if (want == NSC_STRING)
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CANT_REACH(); /* FIXME implement */
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}
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if (CANT_HAPPEN(valtype != want && want != NSC_NOTYPE)) {
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/* make up an error value */
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@ -46,9 +46,10 @@ static char *nstr_parse_val(char *, struct valstr *);
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static int nstr_match_ca(struct valstr *, struct castr *);
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static int nstr_match_val(struct valstr *, struct castr *, int);
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static int nstr_string_ok(struct castr *ca, int idx);
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static struct valstr *nstr_resolve_id(struct valstr *, struct castr *, int, int);
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static struct valstr *nstr_resolve_sel(struct valstr *, struct castr *);
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static struct valstr *nstr_mkselval(struct valstr *, int, struct castr *);
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static struct valstr *nstr_resolve_id(struct valstr *, struct castr *, int, int);
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static int nstr_optype(enum nsc_type, enum nsc_type);
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/*
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* Compile conditions into array NP[LEN].
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@ -68,7 +69,6 @@ nstr_comp(struct nscstr *np, int len, int type, char *str)
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struct nscstr dummy;
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int lft_caidx, rgt_caidx;
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int lft_val, rgt_val;
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int lft_type, rgt_type;
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cond = str;
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for (i = 0; ; ++i, ++np) {
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@ -125,7 +125,7 @@ nstr_comp(struct nscstr *np, int len, int type, char *str)
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} else {
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/*
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* Neither side works as selector value; any identifiers
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* must name selectors.
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* must name selectors or strings.
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*/
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if (!nstr_resolve_id(&np->lft, ca, lft_caidx,
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nstr_string_ok(ca, rgt_caidx)))
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@ -135,29 +135,13 @@ nstr_comp(struct nscstr *np, int len, int type, char *str)
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return -1;
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}
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/* find operator type, coerce operands */
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lft_type = nstr_promote(np->lft.val_type);
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rgt_type = nstr_promote(np->rgt.val_type);
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np->optype = NSC_NOTYPE;
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if (lft_type == NSC_STRING) {
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if (!nstr_coerce_val(&np->rgt, NSC_STRING, str))
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np->optype = NSC_STRING;
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} else if (rgt_type == NSC_STRING) {
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if (!nstr_coerce_val(&np->lft, NSC_STRING, str))
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np->optype = NSC_STRING;
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} else if (lft_type == NSC_DOUBLE) {
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if (!nstr_coerce_val(&np->rgt, NSC_DOUBLE, str))
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np->optype = NSC_DOUBLE;
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} else if (rgt_type == NSC_DOUBLE) {
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if (!nstr_coerce_val(&np->lft, NSC_DOUBLE, str))
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np->optype = NSC_DOUBLE;
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} else {
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if (!nstr_coerce_val(&np->lft, NSC_LONG, str)
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&& !nstr_coerce_val(&np->rgt, NSC_LONG, str))
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np->optype = NSC_LONG;
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}
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if (np->optype == NSC_NOTYPE)
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/* find operator type */
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np->optype = nstr_optype(np->lft.val_type, np->rgt.val_type);
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if (np->optype == NSC_NOTYPE) {
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pr("%.*s -- condition operand type mismatch\n",
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(int)(tail-cond), cond);
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return -1;
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}
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/* another condition? */
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if (*tail == 0)
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@ -436,19 +420,37 @@ nstr_resolve_sel(struct valstr *val, struct castr *ca)
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static struct valstr *
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nstr_mkselval(struct valstr *val, int selval, struct castr *ca)
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{
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if (CANT_HAPPEN(nstr_promote(ca->ca_type) != NSC_LONG
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|| ca->ca_table == EF_BAD)) {
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enum nsc_type type = nstr_promote(ca->ca_type);
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if (CANT_HAPPEN(type != NSC_LONG || ca->ca_table == EF_BAD)) {
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val->val_type = NSC_NOTYPE;
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val->val_cat = NSC_NOCAT;
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return val;
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}
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val->val_type = ca->ca_type;
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val->val_type = type;
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val->val_cat = NSC_VAL;
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val->val_as.lng = selval;
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return val;
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}
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/*
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* Return operator type for operand types LFT, RGT.
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*/
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static int
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nstr_optype(enum nsc_type lft, enum nsc_type rgt)
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{
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lft = nstr_promote(lft);
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rgt = nstr_promote(rgt);
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if (lft == rgt)
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return lft;
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if (lft == NSC_DOUBLE && rgt == NSC_LONG)
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return NSC_DOUBLE;
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if (rgt == NSC_DOUBLE && lft == NSC_LONG)
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return NSC_DOUBLE;
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return NSC_NOTYPE;
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}
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/*
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* Compile a value in STR into VAL.
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* Return a pointer to the first character after the value on success,
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@ -466,57 +468,3 @@ nstr_comp_val(char *str, struct valstr *val, int type)
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return NULL;
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return tail;
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}
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static int
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cond_type_mismatch(char *str)
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{
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if (str)
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pr("%s -- condition operand type mismatch\n", str);
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return -1;
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}
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/*
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* Coerce VAL to promoted value type TO.
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* Return 0 on success, -1 on error.
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* If VAL is evaluated, convert it, else only check.
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* STR is the condition text to be used for error messages. Suppress
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* messages if it is a null pointer.
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*/
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int
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nstr_coerce_val(struct valstr *val, enum nsc_type to, char *str)
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{
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/* FIXME get rid of promotion? */
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enum nsc_type from = nstr_promote(val->val_type);
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if (from == NSC_NOTYPE)
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return 0;
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if (from != to) {
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switch (to) {
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case NSC_STRING:
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return cond_type_mismatch(str); /* FIXME implement */
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case NSC_DOUBLE:
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if (from == NSC_LONG) {
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if (val->val_cat == NSC_VAL)
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val->val_as.dbl = val->val_as.lng;
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} else
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return cond_type_mismatch(str);
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break;
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case NSC_LONG:
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return cond_type_mismatch(str);
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default:
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CANT_REACH();
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to = from;
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}
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}
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if (val->val_cat == NSC_VAL) {
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/* unimplemented conversions; don't currently occur here */
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CANT_HAPPEN(val->val_type == NSC_XCOORD
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|| val->val_type == NSC_YCOORD
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|| val->val_type == NSC_HIDDEN);
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val->val_type = to;
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}
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return 0;
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}
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