/// <summary>
/// Shift given shiftedBlock behind target, if possible
/// </summary>
/// <param name="shiftedBlock"></param>
/// <param name="target"></param>
/// <param name="view"></param>
private bool shiftBehind(ExecutedBlock shiftedBlock, ExecutedBlock target, ExecutionView view)
{
//cumulative list of blocks that has to be shifted
//It has reverse ordering of transformations that will be generated
var shiftedBlocks = new List <ExecutedBlock>();
shiftedBlocks.Add(shiftedBlock);
var borderInstances = new HashSet <Instance>();
borderInstances.UnionWith(view.AffectedInstances(shiftedBlock));
//find all colliding blocks, so we can move them with shifted block if possible
var currentBlock = shiftedBlock;
while (currentBlock != target)
{
currentBlock = view.NextBlock(currentBlock);
if (!canCross(currentBlock, borderInstances, view))
{
//this block cannot be crossed
borderInstances.UnionWith(view.AffectedInstances(currentBlock));
shiftedBlocks.Add(currentBlock);
}
}
//shifting is not possible, due to collisions between blocks
if (!canCross(target, borderInstances, view))
{
return(false);
}
shiftedBlocks.Reverse();
foreach (var block in shiftedBlocks)
{
view.ShiftBehind(block, target);
}
return(true);
}
private bool canCross(ExecutedBlock shiftedBlock, HashSet <Instance> borderInstances, ExecutionView view)
{
foreach (var instance in view.AffectedInstances(shiftedBlock))
{
if (borderInstances.Contains(instance))
{
//there is collision with border
return(false);
}
}
return(true);
}