static VALUE
rb_str_upto(int argc, VALUE *argv, VALUE beg)
{
VALUE end, exclusive;
VALUE current, after_end;
ID succ;
int n, excl, ascii;
rb_encoding *enc;
rb_scan_args(argc, argv, "11", &end, &exclusive);
RETURN_ENUMERATOR(beg, argc, argv);
excl = RTEST(exclusive);
CONST_ID(succ, "succ");
StringValue(end);
enc = rb_enc_check(beg, end);
ascii = (is_ascii_string(beg) && is_ascii_string(end));
/* single character */
if (RSTRING_LEN(beg) == 1 && RSTRING_LEN(end) == 1 && ascii) {
char c = RSTRING_PTR(beg)[0];
char e = RSTRING_PTR(end)[0];
if (c > e || (excl && c == e)) return beg;
for (;;) {
rb_yield(rb_enc_str_new(&c, 1, enc));
if (!excl && c == e) break;
c++;
if (excl && c == e) break;
}
return beg;
}
/* both edges are all digits */
if (ascii && ISDIGIT(RSTRING_PTR(beg)[0]) && ISDIGIT(RSTRING_PTR(end)[0])) {
char *s, *send;
VALUE b, e;
int width;
s = RSTRING_PTR(beg); send = RSTRING_END(beg);
width = rb_long2int(send - s);
while (s < send) {
if (!ISDIGIT(*s)) goto no_digits;
s++;
}
s = RSTRING_PTR(end); send = RSTRING_END(end);
while (s < send) {
if (!ISDIGIT(*s)) goto no_digits;
s++;
}
b = rb_str_to_inum(beg, 10, FALSE);
e = rb_str_to_inum(end, 10, FALSE);
if (FIXNUM_P(b) && FIXNUM_P(e)) {
long bi = FIX2LONG(b);
long ei = FIX2LONG(e);
rb_encoding *usascii = rb_usascii_encoding();
while (bi <= ei) {
if (excl && bi == ei) break;
rb_yield(rb_enc_sprintf(usascii, "%.*ld", width, bi));
bi++;
}
}
else {
ID op = excl ? '<' : rb_intern("<=");
VALUE args[2], fmt = rb_obj_freeze(rb_usascii_str_new_cstr("%.*d"));
args[0] = INT2FIX(width);
while (rb_funcall(b, op, 1, e)) {
args[1] = b;
rb_yield(rb_str_format(numberof(args), args, fmt));
b = rb_funcall(b, succ, 0, 0);
}
}
return beg;
}
/* normal case */
no_digits:
n = rb_str_cmp(beg, end);
if (n > 0 || (excl && n == 0)) return beg;
after_end = rb_funcall(end, succ, 0, 0);
current = rb_str_dup(beg);
while (!rb_str_equal(current, after_end)) {
VALUE next = Qnil;
if (excl || !rb_str_equal(current, end))
next = rb_funcall(current, succ, 0, 0);
rb_yield(current);
if (NIL_P(next)) break;
current = next;
StringValue(current);
if (excl && rb_str_equal(current, end)) break;
if (RSTRING_LEN(current) > RSTRING_LEN(end) || RSTRING_LEN(current) == 0)
break;
}
return beg;
}