#ifndef NSYNC_TESTING_HEAP_H_
#define NSYNC_TESTING_HEAP_H_

/* A heap.
   Optionally, elements may have storage for the index to allow deletions from
   arbitrary elements.  A "set" operation sets the field.  Use heap_no_set when
   no field is available.

   Let:
      set (e,i)   sets the index field of the element e to i
      lt (e0, e1) returns whether element e0 < e1

   If
      "a" is an array,
      "n" is is its length,
   then
      To add an element e:
	ensure there are n+1 elements in a[]
	heap_add (a, n, lt, set, e);  // modifies n
      To remove element i:
	heap_remove (a, n, lt, set, i);  // modifies n
      To replace element i with element e:
	heap_adjust (a, n, lt, set, i, e);
*/


#define h_up_(i)   (((i)-1) >> 1)
#define h_down_(i) (((i)<<1) + 1)

#define h_updownall_(up,a,n,i,lt,set,v,s) \
	do { \
		int i_ = (i); \
		int n_ = (n); \
		int j_; \
		if (up) { \
			for (; i_!=0 && ((j_ = h_up_ (i_)), lt ((v), (a)[j_])); i_ = j_) { \
				(a)[i_] = (a)[j_]; \
				set ((a)[i_], i_); \
			} \
		} else { \
			for (; (j_ = h_down_ (i_)) < n_ && ((j_ += (j_+1 < n_ && \
			       lt ((a)[j_+1], (a)[j_]))), lt ((a)[j_], (v))); i_ = j_) { \
				(a)[i_] = (a)[j_]; \
				set ((a)[i_], i_); \
			} \
		} \
		s; \
	} while (0)

#define heap_no_set(a,b) ((void)0)

#define heap_add(a,n,lt,set,v)      h_updownall_ (1,                    (a),      0, \
	(n), lt, set,     (v), ((a)[i_]=(v),     set ((a)[i_], i_), (n)++))
#define heap_remove(a,n,lt,set,i)   h_updownall_ (lt ((a)[n_], (a)[i_]), (a), --(n), \
	(i), lt, set, (a)[n_], ((a)[i_]=(a)[n_], set ((a)[i_], i_)))
#define heap_adjust(a,n,lt,set,i,v) h_updownall_ (lt ((v),     (a)[i_]), (a),   (n), \
	(i), lt, set,     (v), ((a)[i_]=(v),     set ((a)[i_], i_)))

#endif /*NSYNC_TESTING_HEAP_H_*/