public abstract void Visit(VariableExpression expression);
private Expression ParseIdentifier()
{
if (_current == null)
{
throw new EvaluatorException(_scanner.Column, "Expected function or expression.");
}
if (_current.Type != TokenType.Identifier)
{
return ParseUnary();
}
if (_scanner.PeekToken() == null || (_scanner.PeekToken() != null &&
_scanner.PeekToken().Type != TokenType.LeftParenthesis))
{
// variable
var varExpr = new VariableExpression(_current.Text);
if (_scanner.PeekToken() != null)
{
Expect(MiddleGroupIdentifier);
}
else
{
Consume(); // Reach eof
}
return varExpr;
}
var expr = new FunctionCallExpression(_current.Text);
Expect(TokenType.LeftParenthesis);
while (!_scanner.IsEof())
{
Consume();
expr.Arguments.Add(ParseExpression(true));
if (_current == null)
{
break;
}
if (_current.Type == TokenType.Comma)
{
continue;
}
else if (_current.Type == TokenType.RightParenthesis)
{
Consume();
break;
}
else
{
throw new EvaluatorException(_scanner.Column, "Expected comma or close bracket.");
}
}
return expr;
}