private Stmt ClassDeclaration()
{
Token name = Consume(TokenType.Identifier, "Expect class name.");
Expr superclass = null;
if (Match(TokenType.Less))
{
Consume(TokenType.Identifier, "Expect superclass name.");
superclass = new Expr.Variable(Previous());
}
Consume(TokenType.LeftBrace, "Expect '{' before class body.");
List <Stmt.Function> methods = new List <Stmt.Function>();
while (!Check(TokenType.RightBrace) && !IsAtEnd())
{
methods.Add(Function("method"));
}
Consume(TokenType.RightBrace, "Expect '}' after class body.");
return(new Stmt.Class(name, superclass, methods));
}
private Expr Primary()
{
Expr expr = null;
if (Match(TokenType.False))
{
expr = new Expr.Literal(false);
}
else if (Match(TokenType.True))
{
expr = new Expr.Literal(true);
}
else if (Match(TokenType.Nil))
{
expr = new Expr.Literal(null);
}
else if (Match(TokenType.Number, TokenType.String))
{
expr = new Expr.Literal(Previous().literal);
}
else if (Match(TokenType.Super))
{
Token keyword = Previous();
Consume(TokenType.Dot, "Expect '.' after 'super'.");
Token method = Consume(TokenType.Identifier, "Expect superclass method name.");
expr = new Expr.Super(keyword, method);
}
else if (Match(TokenType.This))
{
expr = new Expr.This(Previous());
}
else if (Match(TokenType.Identifier))
{
expr = new Expr.Variable(Previous());
}
else if (Match(TokenType.LeftParen))
{
expr = Expression();
Consume(TokenType.RightParen, "Expect ')' after expression.");
expr = new Expr.Grouping(expr);
}
else
{
throw Error(Peek(), "Expect expression.");
}
return(expr);
}
// Expr Visitors
public object Visit(Expr.Variable expr)
{
if (scopes.Count > 0)
{
Dictionary <string, Tracker> scope = scopes.Peek();
if (scope.ContainsKey(expr.name.lexeme) && // variable declared
scope[expr.name.lexeme].Initialized == false) // variable not initialized
{
Lox.Error(expr.name, "Cannot read local variable in its own initializer.");
}
}
ResolveLocal(expr, expr.name);
return(null);
}
public object Visit(Expr.Variable expr)
{
return(LookUpVariable(expr.name, expr));
}
public string Visit(Expr.Variable variable)
{
return(variable.name.lexeme);
}