private static void HeapSort(CodeContext /*!*/ context, PythonList list, bool reverse)
{
// for an ascending sort (reverse = false), use a max-heap, and vice-versa
if (reverse)
{
DoHeapify(context, list);
}
else
{
DoHeapifyMax(context, list);
}
int last = list._size - 1;
while (last > 0)
{
// put the root node (max if ascending, min if descending) at the end
list.FastSwap(0, last);
// shrink heap by 1
last--;
// maintain heap invariant
if (reverse)
{
SiftDown(context, list, 0, last);
}
else
{
SiftDownMax(context, list, 0, last);
}
}
}
public static object heappop(CodeContext /*!*/ context, PythonList list)
{
lock (list) {
int last = list._size - 1;
if (last < 0)
{
throw PythonOps.IndexError("index out of range");
}
list.FastSwap(0, last);
list._size--;
SiftDown(context, list, 0, last - 1);
return(list._data[list._size]);
}
}
private static void SiftUpMax(CodeContext /*!*/ context, PythonList heap, int index)
{
while (index > 0)
{
int parent = (index - 1) / 2;
if (IsLessThan(context, heap._data[parent], heap._data[index]))
{
heap.FastSwap(parent, index);
index = parent;
}
else
{
return;
}
}
}
private static void SiftDownMax(CodeContext /*!*/ context, PythonList heap, int start, int stop)
{
int parent = start;
int child;
while ((child = parent * 2 + 1) <= stop)
{
// find the larger sibling
if (child + 1 <= stop && IsLessThan(context, heap._data[child], heap._data[child + 1]))
{
child++;
}
// check if max-heap property is violated
if (IsLessThan(context, heap._data[parent], heap._data[child]))
{
heap.FastSwap(parent, child);
parent = child;
}
else
{
return;
}
}
}
