/// <summary>Executes sort on the Bucket_sort.</summary>
/// <remarks>
/// Executes sort on the Bucket_sort. The result is fed into the indices
/// array in the range between begin (inclusive) and end (exclusive). Uses
/// user supplied sorter to execute sort on each bucket. Users either supply
/// the sorter and use this method of Bucket_sort class, or use other methods
/// to form the buckets and take care of bucket sorting themselves.
/// </remarks>
public void Sort(com.epl.geometry.AttributeStreamOfInt32 indices, int begin, int end, com.epl.geometry.ClassicSort sorter)
{
if (end - begin < 32)
{
sorter.UserSort(begin, end, indices);
return;
}
bool b_fallback = true;
try
{
double miny = com.epl.geometry.NumberUtils.PositiveInf();
double maxy = com.epl.geometry.NumberUtils.NegativeInf();
for (int i = begin; i < end; i++)
{
double y = sorter.GetValue(indices.Get(i));
if (y < miny)
{
miny = y;
}
if (y > maxy)
{
maxy = y;
}
}
if (Reset(end - begin, miny, maxy, end - begin))
{
for (int i_1 = begin; i_1 < end; i_1++)
{
int vertex = indices.Get(i_1);
double y = sorter.GetValue(vertex);
int bucket = GetBucket(y);
m_buckets.Set(bucket, m_buckets.Get(bucket) + 1);
// counting
// values
// in a
// bucket.
m_bucketed_indices.Write(i_1 - begin, vertex);
}
// Recalculate buckets to contain start positions of buckets.
int c = m_buckets.Get(0);
m_buckets.Set(0, 0);
for (int i_2 = 1, n = m_buckets.Size(); i_2 < n; i_2++)
{
int b = m_buckets.Get(i_2);
m_buckets.Set(i_2, c);
c += b;
}
for (int i_3 = begin; i_3 < end; i_3++)
{
int vertex = m_bucketed_indices.Read(i_3 - begin);
double y = sorter.GetValue(vertex);
int bucket = GetBucket(y);
int bucket_index = m_buckets.Get(bucket);
indices.Set(bucket_index + begin, vertex);
m_buckets.Set(bucket, bucket_index + 1);
}
b_fallback = false;
}
}
catch (System.Exception)
{
m_buckets.Resize(0);
m_bucketed_indices.Resize(0);
}
if (b_fallback)
{
sorter.UserSort(begin, end, indices);
return;
}
int j = 0;
for (int i_4 = 0, n = m_buckets.Size(); i_4 < n; i_4++)
{
int j0 = j;
j = m_buckets.Get(i_4);
if (j > j0)
{
sorter.UserSort(begin + j0, begin + j, indices);
}
}
System.Diagnostics.Debug.Assert((j == end));
if (GetBucketCount() > 100)
{
// some heuristics to preserve memory
m_buckets.Resize(0);
m_bucketed_indices.Resize(0);
}
}