private int EvaluateExpression(ExpressionSyntex node)
{
if (node is NumberExpresssionSyntex n)
{
return((int)n.NumberToken.Value);
}
if (node is BinaryExpressionSyntex b)
{
var left = EvaluateExpression(b.Left);
var right = EvaluateExpression(b.Right);
switch (b.OperatorToken.Kind)
{
case SyntexKind.PlusToken:
return(left + right);
case SyntexKind.MinusToken:
return(left - right);
case SyntexKind.StarToken:
return(left * right);
case SyntexKind.SlashToken:
return(left / right);
default:
throw new Exception($"Unexpected binary operator {b.OperatorToken.Kind}");
}
}
if (node is ParenthesisedExpressionSyntex p)
{
return(EvaluateExpression(p.Expression));
}
throw new Exception($"Unexpected node {node.Kind} ");
}
public BinaryExpressionSyntex(ExpressionSyntex left, SyntexToken operatorToken, ExpressionSyntex right)
{
Left = left;
OperatorToken = operatorToken;
Right = right;
}
public ParenthesisedExpressionSyntex(SyntexToken openParenthesisToken, ExpressionSyntex expression, SyntexToken closeParenthesisToken)
{
OpenParenthesisToken = openParenthesisToken;
Expression = expression;
CloseParenthesisToken = closeParenthesisToken;
}
public SyntexTree(IEnumerable <string> diagnostics, ExpressionSyntex root, SyntexToken endOfFileToken)
{
Diagnostics = diagnostics.ToArray();
Root = root;
EndOfFileToken = endOfFileToken;
}
public Evaluator(ExpressionSyntex root)
{
_root = root;
}
