nSearchTreeNode BasicSearchTree::SplitBranch(nSearchTreeNode n,size_t depth)
{
if (!n || !m_Nodes[n] || m_Nodes[n]->GetDepth()==depth)
return n;
// for !n it returns the rootnode
// for !m_Nodes[n], it fails by returning n.
// for m_Nodes[n]->GetDepth()==depth, it's a special case (given position is a node)
// so we just return n.
SearchTreeNode* child = m_Nodes[n];
nSearchTreeNode old_parent = child->GetParent();
// Create new node "middle", add it to old_parent in place of child.
// Calculate the parent offset and the new labels' parameters.
size_t parent_offset = depth - child->GetLabelStartDepth();
nSearchTreeLabel labelno = child->GetLabelNo();
unsigned int oldlabelstart = child->GetLabelStart();
unsigned int oldlabellen = child->GetLabelLen();
unsigned int middle_start = oldlabelstart;
unsigned int middle_len = parent_offset;
unsigned int child_start = middle_start + middle_len;
unsigned int child_len = oldlabellen - middle_len;
wxChar middle_char = m_Labels[labelno][middle_start];
wxChar child_char = m_Labels[labelno][child_start];
// Now we're ready to create the middle node and update accordingly
SearchTreeNode* newnode = CreateNode(depth,old_parent,labelno,middle_start,middle_len);
m_Nodes.push_back(newnode);
nSearchTreeNode middle = m_Nodes.size() - 1;
// Add child to middle
child->SetParent(middle);
child->SetLabel(labelno,child_start,child_len);
child->RecalcDepth(this);
newnode->m_Children[child_char]=n;
child->UpdateItems(this);
// Add middle to old_parent
m_Nodes[old_parent]->m_Children[middle_char]=middle;
return middle;
}
SearchTreePoint BasicSearchTree::AddNode(const wxString& s, nSearchTreeNode nparent)
{
SearchTreePoint result(0,0);
nSearchTreeNode n = 0;
bool found = this->FindNode(s,nparent,&result);
if (!found)
{
// Create new node
// If necessary, split the edge with a new node 'middle'
// If result is exactly a node, middle will be just result.n.
nSearchTreeNode middle = SplitBranch(result.n,result.depth);
// Now add the node to the middle node
SearchTreeNode* newnode;
wxString newlabel;
if (m_Nodes[middle]->IsLeaf())
{
// If it's a leaf node, just extend the label and change
// the new node's depth to reflect the changes.
n = middle;
newnode = m_Nodes[n];
// We take the part of the string that corresponds to node middle.
// Since s starts at nparent's depth, we just get the difference and
// it will be the position inside the string.
newlabel = s.substr(m_Nodes[middle]->GetLabelStartDepth() - m_Nodes[nparent]->GetDepth());
// Modify the leaf node's label to extend the point
// Since it's a leaf node, we just concatenate to the current label the missing part.
unsigned int oldlen = newnode->GetDepth() - newnode->GetLabelStartDepth();
if (oldlen < newlabel.length()) // Safety check against segfaults
{
m_Labels[newnode->GetLabelNo()] << newlabel.substr(oldlen);
m_Labels[newnode->GetLabelNo()].Shrink();
}
newnode->SetLabel(newnode->GetLabelNo(),newnode->GetLabelStart(),newlabel.length());
newnode->RecalcDepth(this);
}
else
{
// Get the string's depth. This will be the depth of our new leaf node.
size_t newdepth = m_Nodes[nparent]->GetDepth() + s.length();
// start = middle's depth - nparent's depth.
newlabel = s.substr(m_Nodes[middle]->GetDepth() - m_Nodes[nparent]->GetDepth());
// Now we create the new label to be accessed by the leaf node "newnode".
m_Labels.push_back(newlabel);
nSearchTreeLabel nlabel = m_Labels.size() - 1;
m_Labels[nlabel].Shrink();
// Finally, we create the new node and link it to "middle".
newnode = CreateNode(newdepth,middle,nlabel,0,newlabel.length());
m_Nodes.push_back(newnode);
n = m_Nodes.size()-1;
m_Nodes[middle]->m_Children[newlabel[0u]]=n;
}
result.n = n;
result.depth = newnode->GetDepth();
}
return result;
}
