private static bool NextNode(CharEnumerator enumerator, out INode node)
{
do
{
switch (enumerator.Current)
{
case '>':
node = new MoveRightNode();
return(true);
case '<':
node = new MoveLeftNode();
return(true);
case '+':
node = new IncrementNode();
return(true);
case '-':
node = new DecrementNode();
return(true);
case ',':
node = new InputNode();
return(true);
case '.':
node = new OutputNode();
return(true);
case '[':
var nodes = new List <INode>();
while (enumerator.MoveNext())
{
switch (enumerator.Current)
{
case ']':
node = new LoopNode(nodes);
return(true);
default:
if (NextNode(enumerator, out var nextNode))
{
nodes.Add(nextNode);
}
break;
}
}
throw new InvalidBFProgramException("Expected more symbols after encountering a loop begin symbol", true);
case ']':
throw new InvalidBFProgramException("Encountered a loop end symbol without matching loop begin", false);
default:
break;
}
}while (enumerator.MoveNext());
node = null;
return(false);
}
public void Visit(DecrementNode node)
{
foreach (var subnode in node)
{
Visit((dynamic)subnode);
}
}
private object DecrementNode(DecrementNode d)
{
var name = d.l.Name;
object output;
if (variables.TryGetValue(name, out output))
{
if (output is decimal)
{
variables[name] = ((decimal)output) + 1;
return(((decimal)output) + 1);
}
else
{
throw(new Exception($"Can't decrement {output.GetType()}"));
}
}
else
{
throw(new Exception("Undefined Variable"));
}
}
public Node Stmt()
{
switch (CurrentToken)
{
case TokenCategory.IDENTIFIER:
var idToken = Expect(TokenCategory.IDENTIFIER);
switch (CurrentToken)
{
case TokenCategory.ASSIGN:
Expect(TokenCategory.ASSIGN);
var ass = new AssignmentNode()
{
AnchorToken = idToken
};
ass.Add(Expr());
Expect(TokenCategory.SEMICOLON);
return(ass);
case TokenCategory.INCREMENT:
Expect(TokenCategory.INCREMENT);
var inc = new IncrementNode()
{
AnchorToken = idToken
};
Expect(TokenCategory.SEMICOLON);
return(inc);
case TokenCategory.DECREMENT:
Expect(TokenCategory.DECREMENT);
var dec = new DecrementNode()
{
AnchorToken = idToken
};
Expect(TokenCategory.SEMICOLON);
return(dec);
case TokenCategory.PARENTHESIS_OPEN:
Expect(TokenCategory.PARENTHESIS_OPEN);
var fun = new FunCallNode()
{
AnchorToken = idToken
};
fun.Add(ExprList());
Expect(TokenCategory.PARENTHESIS_CLOSE);
Expect(TokenCategory.SEMICOLON);
return(fun);
}
break;
case TokenCategory.IF:
return(If());
case TokenCategory.WHILE:
return(While());
case TokenCategory.BREAK:
var bre = new StmtNode()
{
AnchorToken = Expect(TokenCategory.BREAK)
};
Expect(TokenCategory.SEMICOLON);
return(bre);
case TokenCategory.RETURN:
return(Return());
case TokenCategory.SEMICOLON:
return(new StmtNode()
{
AnchorToken = Expect(TokenCategory.SEMICOLON)
});
default:
throw new SyntaxError(firstOfStmt, tokenStream.Current);
}
throw new SyntaxError(firstOfStmt, tokenStream.Current);
}