private Expr Assignment()
{
Expr expr = Or();
if (Match(TokenType.EQUAL))
{
Token equals = Previous();
Expr value = Assignment();
if (expr is Expr.Variable)
{
Token name = ((Expr.Variable)expr).name;
return(new Expr.Assign(name, value));
}
else if (expr is Expr.Get)
{
Expr.Get get = (Expr.Get)expr;
return(new Expr.Set(get.@object, get.name, value));
}
Error(equals, "Invalid assignment target.");
}
return(expr);
}
public object VisitGetExpr(Expr.Get expr)
{
object @object = Evaluate(expr.@object);
if (@object is ElizInstance)
{
return(((ElizInstance)@object).Get(expr.name));
}
throw new RuntimeError(expr.name,
"Only instances have properties.");
}
private Expr Call()
{
Expr expr = Primary();
while (true)
{
if (Match(TokenType.LEFT_PAREN))
{
expr = FinishCall(expr);
}
else if (Match(TokenType.DOT))
{
Token name = Consume(TokenType.IDENTIFIER,
"Expect property name after '.'.");
expr = new Expr.Get(expr, name);
}
else
{
break;
}
}
return(expr);
}
public Void VisitGetExpr(Expr.Get expr)
{
Resolve(expr.@object);
return(null);
}
