/// <summary>
/// Removes a node from this node's children.
/// </summary>
/// <param name="node">The node to remove.</param>
/// <returns>Whether the node was removed successfully.</returns>
///
/// <remarks>
/// Removing fails if the node belongs to another node or to no node at all.
/// </remarks>
public bool RemoveChild(ExpressionTreeNode node)
{
if (node.Parent == this)
{
m_children.Remove(node);
node.Parent = null;
return(true);
}
return(false);
}
/// <summary>
/// Adds a new child to this node's children at the specified index.
/// </summary>
/// <param name="node">The node to add.</param>
/// <param name="index">Specifies where to add the new node.</param>
/// <returns>Whether the addition was successful.</returns>
///
/// <remarks>
/// The addition fails if the new node already has a parent node.
/// </remarks>
public bool AddChild(ExpressionTreeNode node, int index)
{
if (m_children.Contains(node) || node.Parent != null)
{
return(false);
}
m_children.Insert(index, node);
node.Parent = this;
return(true);
}
// recursive helper for creating an expression tree
private ExpressionTreeNode CreateSubTree(IEnumerator <ExpressionToken> tokens)
{
var rootNode = new ExpressionTreeNode();
if (!tokens.MoveNext())
{
throw new Exception("No token on the stack!");
}
var token = tokens.Current;
rootNode.Token = token;
if (token.type == TokenType.Operator)
{
// parse subtrees
int arity = GetOperatorArity(token.token);
for (int i = 0; i < arity; i++)
{
rootNode.AddChild(CreateSubTree(tokens), 0);
}
}
return(rootNode);
}
/// <summary>
/// Creates a new instance of <see cref="ExpressionTree"/> using the specified node as root node.
/// </summary>
/// <param name="rootNode">The node to use as root node.</param>
public ExpressionTree(ExpressionTreeNode rootNode)
{
RootNode = rootNode;
}
/// <summary>
/// Adds a new child to this node's children.
/// </summary>
/// <param name="node">The node to add</param>
/// <returns>Returns whether the addition was successful.</returns>
///
/// <remarks>
/// The addition fails if the new node already has a parent node.
/// The new node is added at the end of the children.
/// </remarks>
public bool AddChild(ExpressionTreeNode node)
{
return(AddChild(node, m_children.Count));
}