peek

/*
 * call-seq: peek(len)
 *
 * Extracts a string corresponding to <tt>string[pos,len]</tt>, without
 * advancing the scan pointer.
 *
 *   s = StringScanner.new('test string')
 *   s.peek(7)          # => "test st"
 *   s.peek(7)          # => "test st"
 *
 */
static VALUE
strscan_peek(VALUE self, VALUE vlen)
{
    struct strscanner *p;
    long len;

    GET_SCANNER(self, p);
    len = NUM2LONG(vlen);
    if (EOS_P(p)) {
        return infect(rb_str_new("", 0), p);
    }
    if (p->curr + len > S_LEN(p)) {
        len = S_LEN(p) - p->curr;
    }
    return extract_beg_len(p, p->curr, len);
}