module builtin struct StringBuilder { buf []byte len int } fn new_string_builder(initial_size int) StringBuilder { return StringBuilder { buf: new_array(0, initial_size, sizeof(byte)) } } fn (b mut StringBuilder) write(s string) { b.buf._push_many(s.str, s.len) b.len += s.len } fn (b mut StringBuilder) writeln(s string) { b.buf._push_many(s.str, s.len) b.buf << `\n` b.len += s.len + 1 } fn (b StringBuilder) str() string { return tos(b.buf.data, b.len) } fn (b StringBuilder) cut(n int) { b.len -= n }