/*
type checking positions
*/
static int typecheck_position (rule srule, int altnr, pos p, int dtype)
{ expr ex = p -> ex;
int rtype = 0;
int ctype = balance_type (srule, altnr, dtype, p -> type);
switch (ex -> tag)
{ case tag_single:
rtype = typecheck_affix (srule, altnr, ex -> u.single, ctype);
break;
case tag_compos:
rtype = typecheck_compos(srule, altnr, ex -> u.compos, ctype);
break;
case tag_concat:
rtype = typecheck_concat(srule, altnr, ex -> u.concat, ctype);
break;
case tag_union:
rtype = typecheck_union (srule, altnr, ex -> u.uni, ctype);
break;
default: bad_tag (ex -> tag, "typecheck_position");
};
if (p -> type != rtype)
{ p -> type = rtype;
change = 1;
};
return (rtype);
};
struct value *lns_make_union(struct info *info,
struct lens *l1, struct lens *l2, int check) {
struct lens *lens = NULL;
if (check) {
struct value *exn = typecheck_union(info, l1, l2);
if (exn != NULL)
return exn;
}
lens = make_lens_binop(L_UNION, info, l1, l2, regexp_union_n);
lens->consumes_value = l1->consumes_value && l2->consumes_value;
return make_lens_value(lens);
}