/// <summary>
/// Default constructor: Initializes the maximum number of child edges allowed in tree
/// Creates child node of type “IMultiWaySuffixEdge”, that implies that the references to child node will be in-memory.
/// </summary>
/// <param name="sequence">Sequence of the tree</param>
/// <param name="maximumChildrenCount">Number of allowed child edges</param>
public MultiWaySuffixTree(ISequence sequence, int maximumChildrenCount)
{
InitializeReferenceSequence(sequence);
_maximumChildrenCount = maximumChildrenCount;
Root = new MultiWaySuffixEdge();
Count++;
}
public virtual IEdge Split(IEdge edge, int splitAt)
{
// This is a leaf node with both start and end indices pointing to
// terminating symbol. Don't insert this.
if (splitAt == _sequence.Count)
{
return(edge);
}
MultiWaySuffixEdge mwCurrentEdge = edge as MultiWaySuffixEdge;
if (mwCurrentEdge == null)
{
throw new ArgumentNullException("edge");
}
// Create the new edge
MultiWaySuffixEdge newEdge =
new MultiWaySuffixEdge(splitAt + 1, mwCurrentEdge.EndIndex);
// Copy the children of old edge to new edge
newEdge.ReplaceChildren(mwCurrentEdge.GetChildren());
// Update the old edge
mwCurrentEdge.EndIndex = splitAt;
// Set new edge as child edge to old edge
mwCurrentEdge.ClearChildren();
mwCurrentEdge.AddChild(newEdge);
Count++;
return(mwCurrentEdge);
}
/// <summary>
/// Find the child edge, whose first character starts with given character.
/// </summary>
/// <param name="edge">Parent edge</param>
/// <param name="character">First character of required edge</param>
/// <returns>Edge found</returns>
public virtual IEdge Find(IEdge edge, byte character)
{
MultiWaySuffixEdge mwEdge = edge as MultiWaySuffixEdge;
if (mwEdge == null)
{
throw new ArgumentNullException("edge");
}
if (mwEdge.GetChildren() == null)
{
return(null);
}
int charIndex = 0;
foreach (IEdge childEdge in mwEdge.GetChildren())
{
charIndex = childEdge.StartIndex;
if (charIndex < _sequence.Count)
{
if (GetReferenceSymbol(charIndex) == character)
{
return(childEdge);
}
}
}
return(null);
}
/// <summary>
/// Update the old node with new node, requires merging the child edges.
/// </summary>
/// <param name="parentEdge">Parent edge.</param>
/// <param name="oldEdge">Old edge</param>
/// <param name="newEdge">new edge</param>
/// <returns></returns>
public virtual bool Update(IEdge parentEdge, IEdge oldEdge, IEdge newEdge)
{
MultiWaySuffixEdge mwParentEdge = parentEdge as MultiWaySuffixEdge;
if (mwParentEdge == null)
{
throw new ArgumentNullException("parentEdge");
}
if (oldEdge == null)
{
throw new ArgumentNullException("oldEdge");
}
if (newEdge == null)
{
throw new ArgumentNullException("newEdge");
}
for (int index = 0; index < mwParentEdge.GetChildren().Length; index++)
{
if (mwParentEdge.GetChildren()[index] == oldEdge)
{
mwParentEdge.GetChildren()[index] = newEdge;
return(true);
}
}
return(false);
}
/// <summary>
/// Remove the edge from tree, the edge and all its children will be removed.
/// </summary>
/// <param name="parentEdge">Parent edge.</param>
/// <param name="edge">Edge to be removed.</param>
/// <returns>Success flag</returns>
public virtual bool Remove(IEdge parentEdge, IEdge edge)
{
MultiWaySuffixEdge mwParentEdge = parentEdge as MultiWaySuffixEdge;
if (mwParentEdge == null)
{
throw new ArgumentNullException("parentEdge");
}
if (edge == null)
{
throw new ArgumentNullException("edge");
}
for (int index = 0; index < mwParentEdge.GetChildren().Length; index++)
{
if (mwParentEdge.GetChildren()[index] == edge)
{
mwParentEdge.GetChildren()[index] = null;
Count--;
return(true);
}
}
return(false);
}
/// <summary>
/// Insert a edge at given parent.
/// </summary>
/// <param name="parentEdge">Parent edge.</param>
/// <param name="startIndex">Start index of edge</param>
/// <param name="endIndex">End index of edge</param>
/// <returns>New edge created</returns>
public override IEdge Insert(IEdge parentEdge, int startIndex, int endIndex)
{
// This is a leaf node with both start and end indices pointing to
// terminating symbol. Don't insert this.
if (startIndex >= Sequence.Count)
{
return(null);
}
if (PersisntThreshold > Count)
{
return(base.Insert(parentEdge, startIndex, endIndex));
}
PersistentMultiWaySuffixEdge edge = new PersistentMultiWaySuffixEdge(
startIndex,
endIndex,
MaximumChildrenCount);
edge.Key = EdgeStore.Write(edge);
// Parent edge of type PersistentMultiWaySuffixEdge
PersistentMultiWaySuffixEdge pmwParentEdge = parentEdge as PersistentMultiWaySuffixEdge;
if (pmwParentEdge != null)
{
pmwParentEdge.AddChild(edge.Key);
Count++;
return(edge);
}
// Parent edge of type MultiWaySuffixEdge
MultiWaySuffixEdge mwParentEdge = parentEdge as MultiWaySuffixEdge;
if (mwParentEdge != null)
{
if (mwParentEdge.GetChildren() == null)
{
mwParentEdge.AddChild(edge);
Count++;
return(edge);
}
if (mwParentEdge.GetChildren().Length < MaximumChildrenCount)
{
mwParentEdge.AddChild(edge);
Count++;
return(edge);
}
// No more children edge can be added.
throw new InvalidOperationException(string.Format(
CultureInfo.CurrentCulture,
"Cannot add more than {0} child nodes to edge.",
MaximumChildrenCount));
}
return(edge);
}
/// <summary>
/// Insert a edge at given parent.
/// </summary>
/// <param name="parentEdge">Parent edge.</param>
/// <param name="startIndex">Start index of edge</param>
/// <param name="endIndex">End index of edge</param>
/// <returns>New edge created</returns>
public virtual IEdge Insert(IEdge parentEdge, int startIndex, int endIndex)
{
// This is a leaf node with both start and end indices pointing to
// terminating symbol. Don't insert this.
if (startIndex >= _sequence.Count)
{
return(null);
}
MultiWaySuffixEdge mwParentEdge = parentEdge as MultiWaySuffixEdge;
if (mwParentEdge == null)
{
throw new ArgumentNullException("parentEdge");
}
if (mwParentEdge.GetChildren() == null)
{
IEdge edge = new MultiWaySuffixEdge(startIndex, endIndex);
mwParentEdge.AddChild(edge);
Count++;
return(edge);
}
if (mwParentEdge.GetChildren().Length < _maximumChildrenCount)
{
IEdge edge = new MultiWaySuffixEdge(startIndex, endIndex);
mwParentEdge.AddChild(edge);
Count++;
return(edge);
}
// No more children edge can be added.
throw new InvalidOperationException(string.Format(
CultureInfo.CurrentCulture,
"Cannot add more than {0} child nodes to edge.",
_maximumChildrenCount));
}
/// <summary>
/// Merge the given branch at the root of Suffix Tree.
/// Asummption:
/// The root node of the given branch contains only one edge, which is the branch to be merged.
/// </summary>
/// <param name="branch">Branch to be merged.</param>
/// <returns>Success flag.</returns>
public bool Merge(IMultiWaySuffixTree branch)
{
if (branch == null)
{
throw new NotImplementedException("branch");
}
MultiWaySuffixEdge mwBranchEdge = branch.Root as MultiWaySuffixEdge;
if (mwBranchEdge.GetChildren() == null)
{
return(false);
}
MultiWaySuffixEdge mwRoot = Root as MultiWaySuffixEdge;
if (mwRoot.GetChildren() == null)
{
mwRoot.AddChild(mwBranchEdge.GetChildren()[0]);
Count += (branch.Count - 1); // - the original root edge of branch
return(true);
}
if (mwRoot.GetChildren().Length < _maximumChildrenCount)
{
mwRoot.AddChild(mwBranchEdge.GetChildren()[0]);
Count += (branch.Count - 1); // - the original root edge of branch
return(true);
}
// No more children edge can be added.
throw new InvalidOperationException(string.Format(
CultureInfo.CurrentCulture,
"Cannot add more than {0} child nodes to edge.",
_maximumChildrenCount));
}
