Node SimpleFactor()
{
// SimpFactor := '(' Expr ')'
// or '|' Expr '|'
// or Number
// or Identifier
// or '-' Factor
Node result;
TokenType token = scanner.Token;
if (token == TokenType.TokenLParen)
{
scanner.Accept();
result = Expression();
if (scanner.Token == TokenType.TokenRParen)
{
scanner.Accept();
}
else
{
status = Status.Error;
}
}
else if (token == TokenType.TokenTube)
{
scanner.Accept();
result = new AbsoluteValueNode(Expression());
if (scanner.Token == TokenType.TokenTube)
{
scanner.Accept();
}
else
{
status = Status.Error;
}
}
else if (token == TokenType.TokenNumber)
{
result = new NumberNode(new Number(scanner.Number));
scanner.Accept();
}
else if (token == TokenType.TokenIdentifer)
{
result = new UnknownNode(scanner.Symbol);
scanner.Accept();
}
else if (token == TokenType.TokenMinus)
{
scanner.Accept();
result = new MultiNode(new NumberNode(new Number(-1)), Factor());
}
else
{
status = Status.Error;
result = null;
}
return(result);
}
public override SimplifyResult Replace(out Node node)
{
if (Children.Count == 1)
{
node = Children[0];
return(new SimplifyResult(true));
}
else if (Children.Count == 0)
{
node = new NumberNode(Number.One);
return(new SimplifyResult(true));
}
foreach (Node n in Children)
{
if (typeof(NumberNode).IsInstanceOfType(n) && ((NumberNode)n).Value.N == 0)
{
node = n; // zero
return(new SimplifyResult(true, true));
}
else if (typeof(SumNode).IsInstanceOfType(n))
{
List <Node> l = new List <Node>();
foreach (Node child in ((SumNode)n).Children)
{
List <Node> ll = new List <Node>(Children);
for (int i = 0; i < ll.Count; i++)
{
if (ll[i] == n)
{
ll.RemoveAt(i);
break;
}
}
ll.Add(child);
l.Add(new MultiNode(ll));
}
node = new SumNode(l);
return(new SimplifyResult(true, true));
}
}
node = null;
return(new SimplifyResult(false));
}
public override SimplifyResult Replace(out Node node)
{
if (Children.Count == 1)
{
node = Children[0];
return(new SimplifyResult(true));
}
else if (Children.Count == 0)
{
node = new NumberNode(Number.Zero);
return(new SimplifyResult(true));
}
else
{
node = null;
return(new SimplifyResult(false));
}
}
public override SimplifyResult Replace(out Node node)
{
if (typeof(NumberNode).IsInstanceOfType(Child))
{
NumberNode n = (NumberNode)Child;
if (n.Value < Number.Zero)
{
node = new NumberNode(Number.Zero - n.Value);
}
else
{
node = n;
}
return(new SimplifyResult(true, true));
}
else
{
node = null; return(new SimplifyResult(false));
}
}
public override SimplifyResult Replace(out Node node)
{
if (Children.Count == 0)
{
node = new NumberNode(Number.One);
return(new SimplifyResult(true));
}
node = Children[0];
for (int i = 1; i < Children.Count; i++)
{
if (Sign[i])
{
node = new MultiNode(Children[i], node);
}
else
{
node = new DivideNode(node, Children[i]);
}
}
return(new SimplifyResult(true));
}
public override SimplifyResult Replace(out Node node)
{
if (typeof(NumberNode).IsInstanceOfType(RChild) ||
((NumberNode)RChild).Value.M == 1)
{
NumberNode n = (NumberNode)RChild;
if (n.Value.N == 0)
{
node = new NumberNode(Number.One);
return(new SimplifyResult(true));
}
else
{
MultiNode result = new MultiNode();
long x = Math.Abs(n.Value.N);
for (long i = 0; i < x; i++)
{
result.Children.Add(LChild);
}
if (n.Value.N < 0)
{
node = new DivideNode(new NumberNode(Number.One), result);
}
else
{
node = result;
}
return(new SimplifyResult(true, true));
}
}
else
{
node = null;
return(new SimplifyResult(false));
}
}