public static Let Parse(Input input, TextWriter output)
{
return(input.RewindOnNull(() =>
{
if (input.Pop(Keyword) == null)
{
return null;
}
var var = Var.Parse(input, output);
if (var == null)
{
output.WriteLine(MessageFormatter.Expected("var"));
return null;
}
if (input.Pop("=") == null)
{
output.WriteLine(MessageFormatter.Expected("="));
return null;
}
var expr = Expr.Parse(input, output);
if (expr == null)
{
output.WriteLine(MessageFormatter.Expected("expression"));
return null;
}
return new Let(var, expr);
}));
}
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 Statement Parse(Input input, TextWriter output)
{
foreach (var commandParser in Parsers)
{
var command = commandParser(input, output);
if (command != null)
{
return(new Statement(command));
}
}
output.WriteLine(MessageFormatter.Expected(Print.Keyword, If.KeywordIf, Goto.Keyword, InputCmd.Keyword, Let.Keyword, Gosub.Keyword,
Return.Keyword, Clear.Keyword, ListCmd.Keyword, Run.Keyword, End.Keyword, Save.Keyword, Load.Keyword, Rem.Keyword));
return(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 Statement Parse(Input input)
{
foreach (var commandParser in Parsers)
{
var command = commandParser.Parse(input);
if (command != null)
{
return(new Statement(command));
}
}
Console.WriteLine("Input: " + input.Body + " " + input.Index);
Console.WriteLine(MessageFormatter.Expected(new List <string> {
Print.Keyword, If.KeywordIf, Goto.Keyword, InputCmd.Keyword, Let.Keyword, Gosub.Keyword,
Return.Keyword, Clear.Keyword, ListCmd.Keyword, Run.Keyword, End.Keyword, Save.Keyword, Load.Keyword, Rem.Keyword
}));
return(null);
}
public static InputCmd Parse(Input input, TextWriter output)
{
return(input.RewindOnNull(() =>
{
var cmd = input.Pop(Keyword);
if (cmd == null)
{
return null;
}
var varList = VarList.Parse(input, output);
if (varList == null)
{
output.WriteLine(MessageFormatter.Expected("var-list"));
return null;
}
return new InputCmd(varList);
}));
}
public static Goto Parse(Input input, TextWriter output)
{
return(input.RewindOnNull(() =>
{
var cmd = input.Pop(Keyword);
if (cmd == null)
{
return null;
}
var expr = Expr.Parse(input, output);
if (expr == null)
{
output.WriteLine(MessageFormatter.Expected("expression"));
return null;
}
return new Goto(expr);
}));
}
private static InputCmd NewMethod(Input input)
{
var cmd = input.Pop(new List <string> {
Keyword
});
if (cmd == null)
{
return(null);
}
var varList = VarList.Parse(input);
if (varList == null)
{
Console.WriteLine(MessageFormatter.Expected("var-list"));
return(null);
}
return(new InputCmd(varList));
}
private static Line NewMethod(Input input)
{
var number = Number.Parse(input);
var statement = Statement.Parse(input);
if (statement == null)
{
Console.WriteLine(MessageFormatter.Expected("statement"));
return(null);
}
var remainder = input.Pop(length: Int32.MaxValue).Trim();
if (remainder.Length != 0)
{
Console.WriteLine(MessageFormatter.Expected($"eol (line was \"{input.Body}\")"));
return(null);
}
return(new Line(number, statement, input.Body));
}
public static If Parse(Input input, TextWriter output)
{
return(input.RewindOnNull(() =>
{
var cmd = input.Pop(KeywordIf);
if (cmd == null)
{
return null;
}
var lhExpr = Expr.Parse(input, output);
if (lhExpr == null)
{
output.WriteLine(MessageFormatter.Expected("expression"));
return null;
}
var relop = Relop.Parse(input);
if (relop == null)
{
output.WriteLine(MessageFormatter.Expected(Relop.Strings));
return null;
}
var rhExpr = Expr.Parse(input, output);
if (rhExpr == null)
{
output.WriteLine(MessageFormatter.Expected("expression"));
return null;
}
var then = input.Pop(KeywordThen);
if (then == null)
{
output.WriteLine(MessageFormatter.Expected(KeywordThen));
return null;
}
var statement = Statement.Parse(input, output);
if (statement == null)
{
output.WriteLine(MessageFormatter.Expected("statement"));
return null;
}
return new If(lhExpr, relop, rhExpr, statement);
}));
}
public static Line Parse(Input input, TextWriter output)
{
return(input.RewindOnNull(() =>
{
var number = Number.Parse(input);
var statement = Statement.Parse(input, output);
if (statement == null)
{
output.WriteLine(MessageFormatter.Expected("statement"));
return null;
}
var remainder = input.Pop(length: Int32.MaxValue).Trim();
if (remainder.Length != 0)
{
output.WriteLine(MessageFormatter.Expected($"eol (line was \"{input.Body}\")"));
return null;
}
return new Line(number, statement, input.Body);
}));
}