public void Init()
{
_testTree = new ParseNode(ParseEnum.Start);
_testTree.AddChild(new ParseNode(ParseEnum.Expression));
_testTree.GetChildren()[0].AddChild(new ParseNode(ParseEnum.Term));
_testTree.GetChildren()[0].AddChild(new ParseNode(ParseEnum.ExpressionAccent));
ParseNode node = _testTree.GetChildren()[0].GetChildren()[0];
node.AddChild(new ParseNode(ParseEnum.Factor));
node.AddChild(new ParseNode(ParseEnum.TermAccent));
node.GetChildren()[0].AddChild(new ParseNode(ParseEnum.Number, "3"));
node.GetChildren()[1].AddChild(new ParseNode(ParseEnum.Empty));
node = _testTree.GetChildren()[0].GetChildren()[1];
node.AddChild(new ParseNode(ParseEnum.Operator, "+"));
node.AddChild(new ParseNode(ParseEnum.Term));
node.AddChild(new ParseNode(ParseEnum.ExpressionAccent));
ParseNode termNode = node.GetChildren()[1];
termNode.AddChild(new ParseNode(ParseEnum.Factor));
termNode.AddChild(new ParseNode(ParseEnum.TermAccent));
termNode.GetChildren()[0].AddChild(new ParseNode(ParseEnum.Number, "4"));
termNode.GetChildren()[1].AddChild(new ParseNode(ParseEnum.Empty));
node.GetChildren()[2].AddChild(new ParseNode(ParseEnum.Empty));
}
private void Expacc()
{
_currentNode.AddChild(new ParseNode(ParseEnum.ExpressionAccent));
_currentNode = _currentNode.GetChildren()[_currentNode.GetChildren().Count - 1];
if (_current is AddSub)
{
_currentNode.AddChild(new ParseNode(ParseEnum.Operator, _current.GetValue()));
if (!_lex.EndOfInput)
{
_current = _lex.GetNextToken();
}
Term();
Expacc();
}
else if (_current is Equals)
{
_currentNode.AddChild(new ParseNode(ParseEnum.Equals));
if (!_lex.EndOfInput)
{
_current = _lex.GetNextToken();
}
Expressie();
}
else
{
_currentNode.AddChild(new ParseNode(ParseEnum.Empty));
}
_currentNode = _currentNode.GetParent();
}
private void Expressie()
{
_currentNode.AddChild(new ParseNode(ParseEnum.Expression));
_currentNode = _currentNode.GetChildren()[_currentNode.GetChildren().Count - 1];
Term();
Expacc();
_currentNode = _currentNode.GetParent();
}
/// <summary>
/// Generates a Queue by walking breadth first through the tree.
/// </summary>
/// <param name="node">Starting node</param>
/// <returns>Queue in breadth first order</returns>
public List<ParseNode> GetBreadthFirstQueue(ParseNode node)
{
List<ParseNode> brQueue = new List<ParseNode>();
Queue<ParseNode> queue = new Queue<ParseNode>();
queue.Enqueue(node);
brQueue.Add(node);
while (queue.Count > 0)
{
ParseNode tempNode = queue.Dequeue();
foreach (ParseNode parseNode in tempNode.GetChildren())
{
queue.Enqueue(parseNode);
brQueue.Add(parseNode);
}
}
return brQueue;
}
/// <summary>
/// Generates a abstract syntrax tree from the given ParseTree
/// </summary>
/// <param name="node">Start node</param>
/// <returns>Abstract syntax tree </returns>
public ASTNode GenerateAST(ParseNode node)
{
ASTNode root;
// Skip start node
if (node.GetEnum() == ParseEnum.Start)
{
node = node.GetChildren()[0];
}
List<ParseNode> bfQueue = GetBreadthFirstQueue(node).FindAll(x => x.GetEnum() == ParseEnum.Operator || x.GetEnum() == ParseEnum.Number
|| x.GetEnum() == ParseEnum.Variable || x.GetEnum() == ParseEnum.Equals);
// If there is only one interesting node no further processing needs to be done.
if (bfQueue.Count == 1)
{
root = ConvertPNtoASTNode(bfQueue[0]);
}
else
{
// Handle special condition
if (bfQueue.Count == 3 &&
(bfQueue.Find(x => x.GetEnum() == ParseEnum.Operator || x.GetEnum() == ParseEnum.Equals) != null))
{
ParseNode op =
bfQueue.Find(x => x.GetEnum() == ParseEnum.Operator || x.GetEnum() == ParseEnum.Equals);
bfQueue.Remove(op);
if (op.GetEnum() == ParseEnum.Equals)
{
root = new EqualSign(op.GetValue());
}
else
{
root = new Operator(op.GetValue());
}
root.LeftChild = ConvertPNtoASTNode(bfQueue[0]);
root.RightChild = ConvertPNtoASTNode(bfQueue[1]);
}
else
{
// Normal routine
// Handles the left and right tree recursivly
ParseNode subTree = node.GetChildren().Find(x => ContainsNode(x, bfQueue[0]));
root = ConvertPNtoASTNode(bfQueue[0]);
if (node.GetChildren()[0].Equals(subTree))
{
subTree.GetChildren().Remove(bfQueue[0]);
root.LeftChild = GenerateAST(subTree);
root.RightChild = GenerateAST(node.GetChildren()[1]);
}
else
{
subTree.GetChildren().Remove(bfQueue[0]);
root.RightChild = GenerateAST(subTree);
root.LeftChild = GenerateAST(node.GetChildren()[0]);
}
}
}
return root;
}
/// <summary>
/// Converts a ParseNode object into it correspondending AST node. Throws an exception when there is no conversion possible.
/// </summary>
/// <param name="parseNode">Parsenode to be converted</param>
/// <returns>AST node</returns>
private ASTNode ConvertPNtoASTNode(ParseNode parseNode)
{
ASTNode ret;
switch (parseNode.GetEnum())
{
case ParseEnum.Number:
ret = new Number(parseNode.GetValue());
break;
case ParseEnum.Operator:
ret = new Operator(parseNode.GetValue());
break;
case ParseEnum.Variable:
ret = new Variable(parseNode.GetValue());
break;
case ParseEnum.Equals:
ret = new EqualSign(parseNode.GetValue());
break;
default:
throw new Exception("Could not convert Parsenode");
}
return ret;
}
private bool ContainsNode(ParseNode startNode, ParseNode nodeToFind)
{
if (startNode.Equals(nodeToFind))
{
return true;
}
return startNode.GetChildren().Exists(x => ContainsNode(x, nodeToFind));
}
private void Factor()
{
_currentNode.AddChild(new ParseNode(ParseEnum.Factor));
_currentNode = _currentNode.GetChildren()[_currentNode.GetChildren().Count - 1];
if (_current is OpenParenthesis)
{
_currentNode.AddChild(new ParseNode(ParseEnum.OpenParenthesis));
_current = _lex.GetNextToken();
Expressie();
if (_current is CloseParenthesis)
{
_currentNode.AddChild(new ParseNode(ParseEnum.CloseParenthesis));
if (!_lex.EndOfInput)
{
_current = _lex.GetNextToken();
}
}
}
else if (_current is Variable)
{
_currentNode.AddChild(new ParseNode(ParseEnum.Variable, _current.GetValue()));
if (!_lex.EndOfInput)
{
_current = _lex.GetNextToken();
}
}
else if (_current is Number)
{
_currentNode.AddChild(new ParseNode(ParseEnum.Number, _current.GetValue()));
if (!_lex.EndOfInput)
{
_current = _lex.GetNextToken();
}
}
else
{
Console.WriteLine("Syntaxfout.");
Stop();
}
_currentNode = _currentNode.GetParent();
}
public Parser(String invoer)
{
_lex = new LexicalScanner(invoer);
_currentNode = _start;
}
private void Termacc()
{
_currentNode.AddChild(new ParseNode(ParseEnum.TermAccent));
_currentNode = _currentNode.GetChildren()[_currentNode.GetChildren().Count - 1];
if (_current is Operator)
{
_currentNode.AddChild(new ParseNode(ParseEnum.Operator, _current.GetValue()));
if (!_lex.EndOfInput)
{
_current = _lex.GetNextToken();
}
Factor();
Termacc();
}
else
{
_currentNode.AddChild(new ParseNode(ParseEnum.Empty));
}
_currentNode = _currentNode.GetParent();
}
private void Term()
{
_currentNode.AddChild(new ParseNode(ParseEnum.Term));
_currentNode = _currentNode.GetChildren()[_currentNode.GetChildren().Count - 1];
Factor();
Termacc();
_currentNode = _currentNode.GetParent();
}
public void SetParent(ParseNode parent)
{
this.Parent = parent;
}
public void AddChild(ParseNode child)
{
child.SetParent(this);
Children.Add(child);
}