/// <summary>
/// Evaluate a list expression
/// </summary>
/// <param name="expr">List expression to evaluate</param>
/// <returns>Evaluated list</returns>
public object VisitListExpr(List expr)
{
HlangList <object> values = new HlangList <object>();
foreach (var item in expr.Values)
{
values.Add(Evaluate(item));
}
return(values);
}
/// <summary>
/// Parse a primary expression
/// </summary>
/// <returns>A primary expression node</returns>
private Expr Primary()
{
// return string, number, bool, or 'nothing' literal
if (Match(TokenType.FALSE))
{
return(new Literal(false));
}
if (Match(TokenType.TRUE))
{
return(new Literal(true));
}
if (Match(TokenType.NOTHING))
{
return(new Literal(null));
}
if (Match(TokenType.NUMBER, TokenType.STRING))
{
return(new Literal(Previous().Literal));
}
// return identifier or grouping
if (Match(TokenType.IDENTIFER))
{
return(new Variable(Previous()));
}
if (Match(TokenType.LEFT_PAREN))
{
Expr expr = Expression();
Consume(TokenType.RIGHT_PAREN, "Expect ')' after expression");
return(new Grouping(expr));
}
// return list literal
if (Match(TokenType.LEFT_BRACKET))
{
HlangList <Expr> values = new HlangList <Expr>();
while (!Match(TokenType.RIGHT_BRACKET))
{
if (!Check(TokenType.COMA))
{
values.Add(Primary());
}
else
{
Advance();
}
}
return(new List(values));
}
if (Match(TokenType.THIS))
{
return(new This(Previous()));
}
if (Match(TokenType.PARENT))
{
return(FinishParentCall(Previous()));
}
throw new ParsingError(Peek(), "Expected an expression");
}
public List(HlangList <Expr> values)
{
Values = values;
}
