private double And(AstNode node)
{
var result = Interpret(node.GetChild(1)) == 1 && Interpret(node.GetChild(2)) == 1
? 1
: 0;
return(result);
}
private static string getStringSubTree(AstNode node,
string indent, bool root)
{
if (node == null)
{
return("");
}
string result = indent;
if (!root)
{
if (node.Index < node.Parent.ChildCount - 1)
{
result += MiddleNodeChar + " ";
indent += ConnectChar + " ";
}
else
{
result += LastNodeChar + " ";
indent += " ";
}
}
result += node + "\n";
for (int i = 0; i < node.ChildCount; i++)
{
result += getStringSubTree(node.GetChild(i), indent, false);
}
return(result);
}
/// <summary>
/// Performs the specified action on an expression tree.
/// </summary>
/// <returns>The top node of the results.</returns>
/// <exception>ApplicationException</exception>
/// <param name="node">The top node of the tree.</param>
/// <param name="data">Data passed to the visitor (Typically not used).</param>
/// <param name="pv">Visitor object that can be used to descend the tree.</param>
/// <param name="stack">The stack to operate on.</param>
/// <exception cref="ApplicationException">If operator must have 3 arguments.</exception>
public virtual object Evaluate( AstNode node, object data, IAstNodeVisitor pv, Stack< double? > stack )
{
if ( node.NumChildren != 3 )
throw new ApplicationException( "If operator must have 3 arguments." );
AstNode condition = node.GetChild( 0 );
condition.Accept( pv, data );
CheckStack( stack );
double? condVal = stack.Pop();
if ( condVal.HasValue && ( condVal > 0.0 ) )
{
AstNode trueNode = node.GetChild( 1 );
trueNode.Accept( pv, data );
return data;
}
AstNode falseNode = node.GetChild( 2 );
falseNode.Accept( pv, data );
return data;
}
private double GreaterThan(AstNode node)
{
var result = Interpret(node.GetChild(1)) > Interpret(node.GetChild(2)) ? 1 : 0;
return(result);
}
private double Not(AstNode node)
{
var result = Interpret(node.GetChild(1)) == 1 ? 0 : 1;
return(result);
}
private double LessThanOrEqual(AstNode node)
{
var result = Interpret(node.GetChild(1)) <= Interpret(node.GetChild(2)) ? 1 : 0;
return(result);
}
private double Equality(AstNode node)
{
var result = Interpret(node.GetChild(1)) == Interpret(node.GetChild(2)) ? 1 : 0;
return(result);
}
private double Plus(AstNode node)
{
var result = Interpret(node.GetChild(1)) + Interpret(node.GetChild(2));
return(result);
}
private double Multiply(AstNode node)
{
var result = Interpret(node.GetChild(1)) * Interpret(node.GetChild(2));
return(result);
}
private double Divide(AstNode node)
{
var result = Interpret(node.GetChild(1)) / Interpret(node.GetChild(2));
return(result);
}
private double Exponent(AstNode node)
{
var result = Math.Pow(Interpret(node.GetChild(1)), Interpret(node.GetChild(2)));
return(result);
}
private double Modulo(AstNode node)
{
var result = Interpret(node.GetChild(1)) % Interpret(node.GetChild(2));
return(result);
}