#ifndef DYNBUF_H__
#define DYNBUF_H__

#include <cstring>
#include <cassert>

// this is a "buffer" that can grow fast
// and is still somewhat space-efficient.
// unlike obstacks or other data structures,
// it never moves data around. basically,
// this is a fast strstream without the overhead.

class dynbuf
{
  struct chunk
  {
    chunk *next;
    int size;
    char data[0];
  };

  char *ptr;
  int room;
  int ext;
  int _size;

  chunk *first, *last;

  void _reserve (int size);
  void clear ();
  void finish ();

public:
  
  dynbuf (int initial = 4096, int extend = 16384);
  ~dynbuf ();

  int size () { return _size + (ptr - last->data); }

  void linearise (void *data);
  char *linearise ();

  char *force (int size)
  {
    if (room < size)
      _reserve (size);

    return ptr;
  }

  char *alloc (int size)
  {
    char *res = force (size);

    room -= size;
    ptr += size;

    return res;
  }

  void fadd (char c) { --room; *ptr++ = c; }
  void fadd (unsigned char c) { fadd (char (c)); }

  void add (const void *p, int len)
  {
    memcpy (alloc (len), p, len);
  }

  void add (char c)
  {
    if (room < 1)
      _reserve (1);

    room--;
    *ptr++ = c;
  }

  void add (const char *s)
  {
     add (s, strlen (s));
  }

  static const int max_sint32_size = 11;
  static const int max_sint64_size = 20;

  void add (sint32 i);
  void add (sint64 i);

  //TODO
  //void add_destructive (dynbuf &buf);

  dynbuf &operator << (char c) { add (c); return *this; }
  dynbuf &operator << (unsigned char c) { return *this << char (c); }
  dynbuf &operator << (const char *s) { add (s); return *this; }
};

#endif