private static Let NewMethod(Input input)
{
if (input.Pop(new List <string> {
Keyword
}) == null)
{
return(null);
}
var var = Var.Parse(input);
if (var == null)
{
Console.WriteLine(MessageFormatter.Expected("var"));
return(null);
}
if (input.Pop(new List <string> {
"="
}) == null)
{
Console.WriteLine(MessageFormatter.Expected("="));
return(null);
}
var expr = Expr.Parse(input);
if (expr == null)
{
Console.WriteLine(MessageFormatter.Expected("expression"));
return(null);
}
return(new Let(var, expr));
}
public static ExprListItem Parse(Input input)
{
var str = Str.Parse(input);
if (str != null)
{
return(new ExprListItem(str));
}
var expr = Expr.Parse(input);
return(expr != null ? new ExprListItem(expr) : null);
}
private static If NewMethod(Input input)
{
var cmd = input.Pop(new List <string> {
KeywordIf
});
if (cmd == null)
{
return(null);
}
var lhExpr = Expr.Parse(input);
if (lhExpr == null)
{
Console.WriteLine(MessageFormatter.Expected("expression"));
return(null);
}
var relop = Relop.Parse(input);
if (relop == null)
{
Console.WriteLine(string.Join("", MessageFormatter.Expected(Relop.Strings)));
return(null);
}
var rhExpr = Expr.Parse(input);
if (rhExpr == null)
{
Console.WriteLine(MessageFormatter.Expected("expression"));
return(null);
}
var then = input.Pop(new List <string> {
KeywordThen
});
if (then == null)
{
Console.WriteLine(MessageFormatter.Expected(KeywordThen));
return(null);
}
var statement = Statement.Parse(input);
if (statement == null)
{
Console.WriteLine(MessageFormatter.Expected("statement"));
return(null);
}
return(new If(lhExpr, relop, rhExpr, statement));
}
private static Gosub NewMethod(Input input)
{
if (input.Pop(new List <string> {
Keyword
}) == null)
{
return(null);
}
var expr = Expr.Parse(input);
if (expr == null)
{
Console.WriteLine(MessageFormatter.Expected("expression"));
return(null);
}
return(new Gosub(expr));
}
public static Factor Parse(Input input)
{
if (Dejavu(input.Index))
{
return(null);
}
indexOnPreviousVisit = input.Index;
var var = Var.Parse(input);
if (var != null)
{
indexOnPreviousVisit = null;
return(new Factor(var));
}
var number = Number.Parse(input);
if (number != null)
{
indexOnPreviousVisit = null;
return(new Factor(number));
}
var expr = Expr.Parse(input);
if (expr != null)
{
indexOnPreviousVisit = null;
return(new Factor(expr));
}
var rnd = Rnd.Parse(input);
if (rnd != null)
{
indexOnPreviousVisit = null;
return(new Factor(rnd));
}
return(null);
}
