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(svn r19239) -Cleanup: Move the HeapifyDown code into its own method (skidd13)

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This commit is contained in:
yexo 2010-02-25 11:47:18 +00:00
parent 7e403a761d
commit b4c51f2ccd
1 changed files with 41 additions and 49 deletions
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90
src/misc/binaryheap.hpp
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@ -52,6 +52,33 @@ public:
m_items = NULL;
}
protected:
/** Heapify (move gap) down */
FORCEINLINE uint HeapifyDown(uint gap, T *item)
{
assert(gap != 0);
uint child = gap * 2; // first child is at [parent * 2]
/* while children are valid */
while (child <= m_size) {
/* choose the smaller child */
if (child < m_size && *m_items[child + 1] < *m_items[child])
child++;
/* is it smaller than our parent? */
if (!(*m_items[child] < *item)) {
/* the smaller child is still bigger or same as parent => we are done */
break;
}
/* if smaller child is smaller than parent, it will become new parent */
m_items[gap] = m_items[child];
gap = child;
/* where do we have our new children? */
child = gap * 2;
}
return gap;
}
public:
/** Return the number of items stored in the priority queue.
* @return number of items in the queue */
@ -73,6 +100,11 @@ public:
return *m_items[1];
}
FORCEINLINE T *End()
{
return m_items[1 + m_size];
}
/** Insert new item into the priority queue, maintaining heap order.
* @return false if the queue is full. */
FORCEINLINE void Push(T& new_item)
@ -104,36 +136,12 @@ public:
{
assert(!IsEmpty());
m_size--;
/* at index 1 we have a gap now */
uint gap = 1;
/* Heapify down:
* last item becomes a candidate for the head. Call it last. */
T& last = *m_items[m_size--];
/* now we must maintain relation between parent and its children:
* parent <= any child
* from head down to the tail */
uint child = 2; // first child is at [parent * 2]
/* while children are valid */
while (child <= m_size) {
/* choose the smaller child */
if (child < m_size && *m_items[child + 1] < *m_items[child])
child++;
/* is it smaller than our parent? */
if (!(*m_items[child] < last)) {
/* the smaller child is still bigger or same as parent => we are done */
break;
}
/* if smaller child is smaller than parent, it will become new parent */
m_items[gap] = m_items[child];
gap = child;
/* where do we have our new children? */
child = gap * 2;
}
T *last = End();
uint gap = HeapifyDown(1, last);
/* move last item to the proper place */
if (m_size > 0) m_items[gap] = &last;
if (!IsEmpty()) m_items[gap] = last;
CheckConsistency();
}
@ -142,17 +150,17 @@ public:
{
/* at position idx we have a gap now */
uint gap = idx;
T& last = *m_items[m_size];
if (idx < m_size) {
assert(idx >= 1);
m_size--;
T *last = End();
/* and the candidate item for fixing this gap is our last item 'last'
* Move gap / last item up: */
while (gap > 1)
{
/* compare [gap] with its parent */
uint parent = gap / 2;
if (last < *m_items[parent]) {
if (*last < *m_items[parent]) {
m_items[gap] = m_items[parent];
gap = parent;
} else {
@ -161,25 +169,9 @@ public:
}
}
uint child = gap * 2;
/* Heapify (move gap) down: */
while (child <= m_size) {
/* choose the smaller child */
if (child < m_size && *m_items[child + 1] < *m_items[child])
child++;
/* is it smaller than our parent? */
if (!(*m_items[child] < last)) {
/* the smaller child is still bigger or same as parent => we are done */
break;
}
/* if smaller child is smaller than parent, it will become new parent */
m_items[gap] = m_items[child];
gap = child;
/* where do we have our new children? */
child = gap * 2;
}
/* move parent to the proper place */
if (m_size > 0) m_items[gap] = &last;
gap = HeapifyDown(gap, last);
/* move last item to the proper place */
if (!IsEmpty()) m_items[gap] = last;
} else {
assert(idx == m_size);
m_size--;