// Order of initialization of the next block is important
      // - don't change unless you know what you are doing!
      uptr_type buffer;
      std::size_t buffer_size;
      char_type* lptr, rptr; // points to actual gap boundaries
      char_type* staging_lptr, staging_rptr; // points to represented gap

      std::size_t character_num;
      std::size_t codepoint_num;
      std::vector<char_type*> lines;

gap_buffer::gap_buffer() :
  buffer(malloc(char_type[alloc_size] * sizeof(char_type), std::free)
  buffer_size(alloc_size),
  lptr(lptr_beg()), rptr(rptr_beg()),
  staging_lptr(lptr), staging_rptr(rptr),
  character_num(0),
  codepoint_num(0) {
  }

  gap_buffer::gap_buffer(const gap_buffer& other) :
  buffer(malloc(char_type[other.buffer_size] * sizeof(char_type)), std::free),
  lptr(other.lptr), rptr(other.rptr),
  staging_lptr(other.staging_lptr), staging_rptr(other.staging_rptr),
  buffer_size(other.buffer_size),
  character_num(other.character_num),
  codepoint_num(other.codepoint_num),
  lines(other.lines) {
    std::memcpy(lptr_beg(), other.lptr_beg(), lsize());
    std::memcpy(rptr, other.rptr, rsize());
  }