/// <summary>Called by DoSingleOperation to split a full node, then retry the add operation.</summary>
/// <remarks>Same arguments and return value as DoSingleOperation.</remarks>
protected virtual int SplitAndAdd(ref AListSingleOperation <K, T> op, out AListNode <K, T> splitLeft, out AListNode <K, T> splitRight)
{
// Tell DoSingleOperation not to send notifications to the observer
op.AggregateChanged |= 2;
int divAt = _list.Count >> 1;
var mid = _list[divAt];
var left = new BListLeaf <K, T>(_maxNodeSize, _list.CopySection(0, divAt));
var right = new BListLeaf <K, T>(_maxNodeSize, _list.CopySection(divAt, _list.Count - divAt));
int sizeChange;
if (op.CompareToKey(mid, op.Key) >= 0)
{
sizeChange = left.DoSingleOperation(ref op, out splitLeft, out splitRight);
}
else
{
op.BaseIndex += left.TotalCount;
sizeChange = right.DoSingleOperation(ref op, out splitLeft, out splitRight);
}
op.AggregateChanged &= unchecked ((byte)~2);
// (splitLeft may be non-null, meaning that the highest key changed, which doesn't matter here.)
Debug.Assert(splitRight == null);
Debug.Assert(sizeChange == 1);
splitLeft = left;
splitRight = right;
return(sizeChange);
}
/// <summary>Performs a retrieve, add, remove or replace operation on a
/// single item in an organized A-list (such as a B+ tree).</summary>
/// <param name="op">An object that describes the operation to be performed
/// and the parameters of the tree (comparers and observers).</param>
/// <param name="splitLeft">null if the operation completed normally. If an
/// item was added and the node split, splitLeft and splitRight are new
/// nodes that each contain roughly half of the items from this node.
/// <para/>
/// If an item was removed and the node became undersized, splitLeft is set
/// to this (the node itself) and splitRight is set to null. Likewise, if
/// the aggregate value of the node changed (in a B+tree, this means that
/// the highest key changed) then splitLeft is set to the node itself and
/// splitRight is set to null.
/// </param>
/// <returns>Returns 1 if a new item was added, -1 if an item was removed,
/// or 0 if the number of items in the tree did not change.</returns>
/// <exception cref="NotSupportedException">This node does not belong to an
/// organized tree.</exception>
/// <exception cref="KeyAlreadyExistsException">The key op.NewKey already
/// existed in the tree and op.Mode was
/// <see cref="AListOperation"/>.AddOrThrow.</exception>
/// <remarks>
/// If op.Mode is <see cref="AListOperation"/>.ReplaceIfPresent, this method
/// informs the caller when replacement occurs in this mode by changing
/// op.Mode to AddDuplicateMode.ReplaceExisting.
/// </remarks>
public virtual int DoSingleOperation(ref AListSingleOperation <K, T> op, out AListNode <K, T> splitLeft, out AListNode <K, T> splitRight)
{
throw new NotSupportedException();
}
public override int DoSingleOperation(ref AListSingleOperation <K, T> op, out AListNode <K, T> splitLeft, out AListNode <K, T> splitRight)
{
Debug.Assert(!IsFrozen || op.Mode == AListOperation.Retrieve);
AssertValid();
var tob = GetObserver(op.List);
int i = BinarySearchK(op.Key, op.CompareKeys);
if (op.Mode != AListOperation.Retrieve)
{
AutoClone(ref _children[i].Node, this, tob);
if (op.Mode >= AListOperation.Add && _children[i].Node.IsFullLeaf)
{
TryToShiftAnItemToSiblingOfLeaf(i, tob);
// Binary search result might now be off-by-1
i = BinarySearchK(op.Key, op.CompareKeys);
}
}
AssertValid();
op.BaseIndex += _children[i].Index;
int sizeChange = _children[i].Node.DoSingleOperation(ref op, out splitLeft, out splitRight);
if (sizeChange != 0)
{
AdjustIndexesAfter(i, sizeChange);
}
// Handle child split / undersized / highest key changed
if (splitLeft != null)
{
if (splitRight != null)
{
splitLeft = HandleChildSplit(i, splitLeft, ref splitRight, tob);
}
else
{
// Node is undersized and/or highest key changed
bool flagParent = false;
if (op.AggregateChanged != 0)
{
if (i < _childCount - 1)
{
_highestKey[i] = op.AggregateKey;
op.AggregateChanged = 0;
}
else
{
// Update highest key in parent node instead
flagParent = true;
}
}
if (splitLeft.IsUndersized)
{
flagParent |= HandleUndersized(i, tob);
}
if (flagParent)
{
splitLeft = this;
}
else
{
splitLeft = null;
}
}
}
AssertValid();
return(sizeChange);
}
public override int DoSingleOperation(ref AListSingleOperation <K, T> op, out AListNode <K, T> splitLeft, out AListNode <K, T> splitRight)
{
T searchItem = op.Item;
int index = _list.BinarySearch(op.Key, op.CompareToKey, op.LowerBound);
if (op.Found = (index >= 0))
{
op.Item = _list[index]; // save old value
if (op.RequireExactMatch && (searchItem == null ? op.Item == null : !searchItem.Equals(op.Item)))
{
op.Found = false;
}
}
else
{
index = ~index;
}
splitLeft = splitRight = null;
op.BaseIndex += (uint)index;
if (op.Mode == AListOperation.Retrieve)
{
return(0);
}
if (op.Mode >= AListOperation.Add)
{
// Possible operations: Add, AddOrReplace, AddIfNotPresent, AddOrThrow
if (_list.Count >= _maxNodeSize && (op.Mode == AListOperation.Add || !op.Found))
{
op.BaseIndex -= (uint)index;
op.Item = searchItem;
return(SplitAndAdd(ref op, out splitLeft, out splitRight));
}
if (op.Found && op.Mode != AListOperation.Add)
{
if (op.Mode == AListOperation.AddOrThrow)
{
throw new KeyAlreadyExistsException();
}
else if (op.Mode == AListOperation.AddIfNotPresent)
{
return(0);
}
}
else // add new item
{
if (HasListChanging(op.List))
{
CallListChanging(op.List, new ListChangeInfo <T>(NotifyCollectionChangedAction.Add, (int)op.BaseIndex, 1, Iterable.Single(searchItem)));
}
if (index == _list.Count)
{ // Highest key may change
splitLeft = this;
op.AggregateChanged |= 1;
op.AggregateKey = GetKey(op.List, searchItem);
}
_list.AutoRaiseCapacity(1, _maxNodeSize);
_list.Insert(index, searchItem);
if (GetObserver(op.List) != null)
{
if ((op.AggregateChanged & 2) == 0)
{
GetObserver(op.List).ItemAdded(searchItem, this);
}
}
return(1);
}
Debug.Assert(op.Mode == AListOperation.AddOrReplace);
}
else if (op.Found)
{
// Possible operations: ReplaceIfPresent, Remove
if (op.Mode == AListOperation.Remove)
{
if (HasListChanging(op.List))
{
CallListChanging(op.List, new ListChangeInfo <T>(NotifyCollectionChangedAction.Remove, (int)op.BaseIndex, -1, null));
}
_list.RemoveAt(index);
if (index == _list.Count)
{ // Highest key may change
splitLeft = this;
if (_list.Count != 0)
{
op.AggregateChanged |= 1;
op.AggregateKey = GetKey(op.List, _list.Last);
}
}
else if (IsUndersized)
{
splitLeft = this;
}
if (GetObserver(op.List) != null)
{
Debug.Assert((op.AggregateChanged & 2) == 0);
GetObserver(op.List).ItemRemoved(op.Item, this);
}
return(-1);
}
Debug.Assert(op.Mode == AListOperation.ReplaceIfPresent);
}
else
{
Debug.Assert(op.Mode == AListOperation.Remove || op.Mode == AListOperation.ReplaceIfPresent);
return(0); // can't remove/replace because item was not found.
}
// Fallthrough action: replace existing item
Debug.Assert(op.Found);
if (HasListChanging(op.List))
{
CallListChanging(op.List, new ListChangeInfo <T>(NotifyCollectionChangedAction.Replace, (int)op.BaseIndex, 0, Iterable.Single(searchItem)));
}
_list[index] = searchItem;
if (index + 1 == _list.Count)
{ // Highest key may change
splitLeft = this;
op.AggregateChanged |= 1;
op.AggregateKey = GetKey(op.List, searchItem);
}
if (GetObserver(op.List) != null)
{
GetObserver(op.List).ItemRemoved(op.Item, this);
GetObserver(op.List).ItemAdded(searchItem, this);
}
return(0);
}