/// <summary>
/// Moves to the next edge and returns the pointer of that next edge. Returns NO_EDGE if no next edge was found.
///
/// The given pointer is expected to be the first position of an edge.
/// </summary>
private uint MoveNextEdge(uint edgePointer)
{
// move past first fixed-data fields to the last one.
var data = _edges[edgePointer];
if (data == NO_EDGE)
{ // just move to the first non-NO_EDGE field.
while (data == NO_EDGE)
{
edgePointer++;
data = _edges[edgePointer];
}
return(edgePointer);
}
edgePointer += (uint)_fixedEdgeDataSize;
data = _edges[edgePointer];
while (!DirectedDynamicGraph.IsLastField(data))
{ // move until the last data field.
edgePointer++;
data = _edges[edgePointer];
}
if (DirectedDynamicGraph.IsLastFieldInLastEdge(data))
{ // if the last data field is the last edge then just stop.
return(NO_EDGE);
}
edgePointer++;
data = _edges[edgePointer];
while (data == NO_EDGE)
{
edgePointer++;
data = _edges[edgePointer];
}
return(edgePointer);
}
/// <summary>
/// Removes an edge and moves to the next edge after the removed edge. Returns NO_EDGE if no next edge was found.
///
/// The given pointer is expected to be the first position of an edge starting a the given vertex. The previous edge pointer is NO_EDGE if there is not previous edge.
/// </summary>
private uint RemoveEdge(uint vertex, uint previousEdgePointer, uint edgePointer, uint nextPointer)
{
var originalEdgePointer = edgePointer;
if (previousEdgePointer == NO_EDGE && nextPointer == NO_EDGE)
{ // only one edge left.
_vertices[vertex] = NO_EDGE;
return(NO_EDGE);
}
var startPointer = edgePointer;
// remove the fixed-data.
for (var i = 0; i < _fixedEdgeDataSize - 1; i++)
{
_edges[edgePointer] = NO_EDGE;
edgePointer++;
}
var data = _edges[edgePointer];
while (!DirectedDynamicGraph.IsLastField(data))
{ // move until the last data field.
_edges[edgePointer] = NO_EDGE;
edgePointer++;
data = _edges[edgePointer];
}
if (DirectedDynamicGraph.IsLastFieldInLastEdge(data))
{ // if the last data field is the last edge then just stop.
if (!this.MarkAsLast(previousEdgePointer))
{ // there is no data at the previous edge, this can only mean one thing: no more edges left.
_vertices[vertex] = NO_EDGE;
}
return(NO_EDGE);
}
_edges[edgePointer] = NO_EDGE;
return(edgePointer + 1);
}
/// <summary>
/// Compresses the data in this graph to it's smallest size.
/// </summary>
public void Compress(bool toReadonly, out long maxEdgeId)
{
// trim first.
this.Trim();
// build a list of all vertices sorted by their first position.
var sortedVertices = new MemoryArray <uint>(_vertices.Length);
for (uint i = 0; i < sortedVertices.Length; i++)
{
sortedVertices[i] = i;
}
// sort vertices and coordinates.
QuickSort.Sort((i) => _vertices[sortedVertices[i]] * sortedVertices.Length +
sortedVertices[i],
(i, j) =>
{
var tempRef = sortedVertices[i];
sortedVertices[i] = sortedVertices[j];
sortedVertices[j] = tempRef;
}, 0, this.VertexCount - 1);
// move data down.
uint pointer = 0;
for (uint i = 0; i < sortedVertices.Length; i++)
{
var vertex = sortedVertices[i];
var vertexPointer = _vertices[vertex];
if (vertexPointer == NO_EDGE)
{
continue;
}
_vertices[vertex] = pointer;
// skip removed data.
var pointerBefore = pointer;
while (_edges[vertexPointer] == NO_EDGE)
{
vertexPointer++;
}
do
{
// copy fixed-data.
for (var e = 0; e < _fixedEdgeDataSize; e++)
{
_edges[pointer + e] = _edges[vertexPointer + e];
}
pointer += (uint)_fixedEdgeDataSize;
vertexPointer += (uint)_fixedEdgeDataSize;
while (!DirectedDynamicGraph.IsLastField(_edges[pointer - 1]))
{
_edges[pointer] = _edges[vertexPointer];
pointer++;
vertexPointer++;
}
} while (!DirectedDynamicGraph.IsLastFieldInLastEdge(_edges[pointer - 1]));
var count = pointer - pointerBefore;
if (!toReadonly && count > 2 && !((count & (count - 1)) == 0))
{ // next power of 2, don't do this on readonly to save space.
count |= count >> 1;
count |= count >> 2;
count |= count >> 4;
count |= count >> 8;
count |= count >> 16;
count++;
pointer += (count - (pointer - pointerBefore));
}
}
_nextEdgePointer = pointer;
_readonly = toReadonly;
// store the max edge id.
_edges.Resize(_nextEdgePointer);
maxEdgeId = _edges.Length;
}