#ifndef UTIL_H__
#define UTIL_H__

#if __GNUC__ >= 3
# define is_constant(c) __builtin_constant_p (c)
#else
# define is_constant(c) 0
#endif

#include <cstddef>

#include <glib.h>

// makes dynamically allocated objects zero-initialised
struct zero_initialised
{
  void *operator new (size_t s, void *p)
  {
    memset (p, 0, s);
    return p;
  }

  void *operator new (size_t s)
  {
    return g_slice_alloc0 (s);
  }

  void *operator new[] (size_t s)
  {
    return g_slice_alloc0 (s);
  }

  void operator delete (void *p, size_t s)
  {
    g_slice_free1 (s, p);
  }

  void operator delete[] (void *p, size_t s)
  {
    g_slice_free1 (s, p);
  }
};

void throw_bad_alloc () throw (std::bad_alloc);

void *alloc (int s) throw (std::bad_alloc);
void dealloc (void *p, int s) throw ();

// a STL-compatible allocator that uses g_slice
// boy, this is verbose
template<typename Tp>
struct slice_allocator
{
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;
  typedef Tp *pointer;
  typedef const Tp *const_pointer;
  typedef Tp &reference;
  typedef const Tp &const_reference;
  typedef Tp value_type;

  template <class U> 
  struct rebind
  {
    typedef slice_allocator<U> other;
  };

  slice_allocator () throw () { }
  slice_allocator (const slice_allocator &o) throw () { }
  template<typename Tp2>
  slice_allocator (const slice_allocator<Tp2> &) throw () { }

  ~slice_allocator () { }

  pointer address (reference x) const { return &x; }
  const_pointer address (const_reference x) const { return &x; }

  pointer allocate (size_type n, const_pointer = 0)
  {
    return static_cast<pointer>(alloc (n * sizeof (Tp)));
  }

  void deallocate (pointer p, size_type n)
  {
    dealloc (static_cast<void *>(p), n);
  }

  size_type max_size ()const throw ()
  {
    return size_t (-1) / sizeof (Tp);
  }

  void construct (pointer p, const Tp &val)
  {
    ::new (p) Tp (val);
  }

  void destroy (pointer p)
  {
    p->~Tp ();
  }
};

struct refcounted
{
  mutable int refcnt;
  refcounted () : refcnt (0) { }
  void refcnt_inc () { ++refcnt; }
  void refcnt_dec () { --refcnt;
  if (refcnt < 0)abort();}//D
};

template<class T>
struct refptr
{
  T *p;

  refptr () : p(0) { }
  refptr (const refptr<T> &p) : p(p.p) { if (p) p->refcnt_inc (); }
  refptr (T *p) : p(p) { if (p) p->refcnt_inc (); }
  ~refptr () { if (p) p->refcnt_dec (); }

  const refptr<T> &operator =(T *o)
  {
    if (p) p->refcnt_dec ();
    p = o;
    if (p) p->refcnt_inc ();

    return *this;
  }

  const refptr<T> &operator =(const refptr<T> o)
  {
    *this = o.p;
    return *this;
  }

  T &operator * () const { return *p; }
  T *operator ->() const { return p; }

  operator T *() const { return p; }
};

struct str_hash
{
  std::size_t operator ()(const char *s) const
  {
    unsigned long hash = 0;

    /* use the one-at-a-time hash function, which supposedly is
     * better than the djb2-like one used by perl5.005, but
     * certainly is better then the bug used here before.
     * see http://burtleburtle.net/bob/hash/doobs.html
     */
    while (*s)
      {
        hash += *s++;
        hash += hash << 10;
        hash ^= hash >>  6;
      }

    hash += hash <<  3;
    hash ^= hash >> 11;
    hash += hash << 15;

    return hash;
  }
};

struct str_equal
{
  bool operator ()(const char *a, const char *b) const
  {
    return !strcmp (a, b);
  }
};

#include <vector>

template<class obj>
struct unordered_vector : std::vector<obj, slice_allocator<obj> >
{
  typedef typename unordered_vector::iterator iterator;

  void erase (unsigned int pos)
  {
    if (pos < this->size () - 1)
      (*this)[pos] = (*this)[this->size () - 1];

    this->pop_back ();
  }

  void erase (iterator i)
  {
    erase ((unsigned int )(i - this->begin ()));
  }
};

template<typename T, typename U> static inline T min (T a, U b) { return a < (T)b ? a : (T)b; }
template<typename T, typename U> static inline T max (T a, U b) { return a > (T)b ? a : (T)b; }
template<typename T, typename U, typename V> static inline T clamp (T v, U a, V b) { return v < (T)a ? a : v >(T)b ? b : v; }

template<typename T, typename U> static inline void swap (T& a, U& b) { T t=a; a=(T)b; b=(U)t; }

// basically does what strncpy should do, but appends "..." to strings exceeding length
void assign (char *dst, const char *src, int maxlen);

// type-safe version of assign
template<int N>
inline void assign (char (&dst)[N], const char *src)
{
  assign ((char *)&dst, src, N);
}

#endif