Enums.

docs/language/dartLangSpec.tex

Index: docs/language/dartLangSpec.tex
===================================================================
--- docs/language/dartLangSpec.tex	(revision 39350)
+++ docs/language/dartLangSpec.tex	(working copy)
@@ -1206,7 +1206,7 @@
 
 Then, the initializer list of the constructor $S$ (respectively $S.id$) is executed with respect to the bindings that resulted from the evaluation of the argument list,  with \THIS{} bound to the current binding of \THIS{}, and  the type parameters (if any) of class $S$ bound to the current bindings of $U_1, , \ldots, U_m$.
 
-It is a compile-time error if class $S$ does not declare a generative constructor named $S$ (respectively $S.id$)
+It is a compile-time error if class $S$ does not declare a generative constructor named $S$ (respectively $S.id$).
 
 \subsubsection{Factories}
 \label{factories}
@@ -1510,7 +1510,7 @@
 %} 
 
 %It is a compile-time error if  the \EXTENDS{} clause of a class $C$ includes a type expression that does not denote a class available in the lexical scope of $C$. 
-It is a compile-time error if  the \EXTENDS{} clause of a class $C$ specifies a malformed  type or a deferred type (\ref{staticTypes}) as a superclass.
+It is a compile-time error if  the \EXTENDS{} clause of a class $C$ specifies an enumerated type (\ref{enums}), a malformed  type or a deferred type (\ref{staticTypes}) as a superclass.
 % too strict? Do we e want extends List<Undeclared> to work as List<dynamic>? 
 
 \commentary{ The type parameters of a generic class are available in the lexical scope of the superclass clause, potentially shadowing classes in the surrounding scope. The following code is therefore illegal and should cause a compile-time error:
@@ -1633,7 +1633,7 @@
     .
 \end{grammar}
 
-It is a compile-time error if  the \IMPLEMENTS{}  clause of a class $C$ specifies a type variable as a superinterface. It is a compile-time error if  the  \IMPLEMENTS{} clause of a class $C$ specifies  a malformed type or deferred type (\ref{staticTypes}) as a superinterface  It is a compile-time error if the \IMPLEMENTS{} clause of a class $C$ specifies type \DYNAMIC{} as a superinterface. It is a compile-time error if  the  \IMPLEMENTS{} clause of a class $C$ specifies  a type $T$ as a superinterface more than once.
+It is a compile-time error if  the \IMPLEMENTS{}  clause of a class $C$ specifies a type variable as a superinterface. It is a compile-time error if  the  \IMPLEMENTS{} clause of a class $C$ specifies an enumerated type (\ref{enums}),  a malformed type or deferred type (\ref{staticTypes}) as a superinterface  It is a compile-time error if the \IMPLEMENTS{} clause of a class $C$ specifies type \DYNAMIC{} as a superinterface. It is a compile-time error if  the  \IMPLEMENTS{} clause of a class $C$ specifies  a type $T$ as a superinterface more than once.
 It is a compile-time error if the superclass of a class $C$ is specified as a superinterface of $C$.
 
 \rationale{
@@ -1824,7 +1824,7 @@
 
 If the mixin application declares support for interfaces, the resulting class implements those interfaces.
 
-It is a compile-time error if $S$ is a malformed type. It is a compile-time error if $M$ (respectively, any of $M_1, \ldots, M_k$) is a malformed type. It is a compile time error if a well formed mixin cannot be derived from $M$ (respectively, from each of $M_1, \ldots, M_k$). 
+It is a compile-time error if $S$ is an enumerated type (\ref{enums}) or a malformed type. It is a compile-time error if $M$ (respectively, any of $M_1, \ldots, M_k$) is an enumerated type (\ref{enums}) or a malformed type. It is a compile time error if a well formed mixin cannot be derived from $M$ (respectively, from each of $M_1, \ldots, M_k$). 
 
 Let $K$ be a class declaration  with the same constructors, superclass and interfaces as $C$,  and the instance members declared by $M$ (respectively $M_1, \ldots, M_k$). It is a static warning if the declaration of $K$ would cause a static warning.  It is a compile-time error if the declaration of $K$ would cause a compile-time error.
 
@@ -1876,6 +1876,47 @@
 }
 
 
+\section{Enums}
+\label{enums}
+
+An {\em enumerated type}, or {\em enum}, is used to represent a fixed number of constant values.
+
+\begin{grammar}
+{\bf enumType:}
+metadata \ENUM{} id `\{' id [`,' id]* [`,'] `\}'
+    .
+\end{grammar}
+
+The declaration of an enum of the form \code{metadata \ENUM{} E \{ id$_1$, \ldots id$_n$\};}

[kasperl, 2014/08/19 05:04:35]

You could consider calling these id$_0$ to id$_{n-1}$ to avoid confusion with
the index.

[gbracha, 2014/08/19 17:54:40]

Done.

+has the same effect as a class declaration
+
+\begin{dartCode}
+metadata \CLASS{} E \{
+  \FINAL{} int index;
+  \FINAL{} String \_name;
+  \CONST{} E(\THIS{}.index,\THIS{}.\_name);
+  \STATIC{} \CONST{} E id$_1$ = \CONST{} E(0, `id$_1$');
+  $\ldots$
+  \STATIC{} \CONST{} E id$_n$ = const E(n - 1, `id$_{n-1}$');

[kasperl, 2014/08/19 05:04:35]

`id$_{n-1}$' should be `id$_n$'.

[gbracha, 2014/08/19 17:54:40]

Not anymore.

+
+  \STATIC{} \CONST{} List$<$E$>$ values = const $<$E$>$[id$_1 \ldots $ id$_n$];
+  String toString() =$>$ `E.\$\_name';
+\}
+\end{dartCode}
+
+
+
+It is compile-time error to access the private fields of an enumerated type anywhere outside its definition.

[kasperl, 2014/08/19 05:04:35]

How can we tell statically?

Is there any way we can specify it so that enums are conceptually in their own
library so the library privacy mechanism works for us? 

[gbracha, 2014/08/19 17:54:41]

The problem is that the surrounding library would have to have an import. Note
that nothing says you have to actually implement things using a _name field.
since the field is hidden everywhere including reflection. So  strictly
speaking, the spec is fine. It might be clearer to implementors if we did give
some suitable scheme in the spec - but it is all overspecification.

Anyway, the map idea works better, and eliminates the need for a special rule
etc. Much nicer.

+
+\commentary {
+It is also a compile-time error to subclass, mix-in or implement an enum or to explicitly instantiate an enum.  These restrictions are given in normative form in sections \ref{superclasses}, \ref{superinterfaces}, \ref{mixinApplication} and \ref{instanceCreation} as appropriate.
+
+All of these restrictions should be enforced by the implementation even in the case of reflection.
+}
+
+% should this be rephrased so that these rules go elsewhere (i.e., in the rules for new/const/extends/implements/with?)

[kasperl, 2014/08/19 05:04:35]

Haven't you already done so?

[gbracha, 2014/08/19 17:54:41]

Yes, I have. This is just an old comment. I'll get rid of it.

+
+
 \section{Generics}
 \label{generics}
 
@@ -2777,6 +2818,18 @@
 \CONST{} $T.id(a_1, \ldots , a_n, x_{n+1}: a_{n+1}, \ldots , x_{n+k}: a_{n+k})$,  
 
 \CONST{} $T(a_1, \ldots , a_n, x_{n+1}: a_{n+1}, \ldots , x_{n+k}: a_{n+k})$ is malformed (\ref{dynamicTypeSystem}) or malbounded (\ref{parameterizedTypes}).
+
+It is a compile-time error if the type $T$ in an instance creation expression of one of  the forms 

[kasperl, 2014/08/19 05:04:35]

one of  the forms -> one of the forms (I know it will not be visible in the PDF
version, but anyway).

[gbracha, 2014/08/19 17:54:40]

Done.

+
+\NEW{} $T.id(a_1, \ldots , a_n, x_{n+1}: a_{n+1}, \ldots , x_{n+k}: a_{n+k})$,  
+
+\NEW{} $T(a_1, \ldots , a_n, x_{n+1}: a_{n+1}, \ldots , x_{n+k}: a_{n+k})$,
+
+\CONST{} $T.id(a_1, \ldots , a_n, x_{n+1}: a_{n+1}, \ldots , x_{n+k}: a_{n+k})$,  
+
+\CONST{} $T(a_1, \ldots , a_n, x_{n+1}: a_{n+1}, \ldots , x_{n+k}: a_{n+k})$ 
+
+is an enumerated type (\ref{enums}).
 %any of the type arguments to a constructor of a generic type $G$ invoked by a new expression or a constant object expression are not subtypes of the bounds of the corresponding formal type parameters of $G$.
 
 
@@ -4659,6 +4712,17 @@
   Very elaborate code in a case clause is probably bad style in any case, and such code can always be refactored.
 }
  
+ It is a static warning if all of the following conditions hold:
+ \begin{itemize}
+\item  The switch statement does not have a default clause.
+ \item The static type of $e$ is an enumerated typed with elements $id_1, \ldots, id_n$.
+\item The sets $\{e_1, \ldots,  e_k\} $ and $\{id_1, \ldots, id_n\}$ are not the same.
+\end{itemize}
+
+\commentary{
+In other words, a warning will be issued if a switch statement over an enum is not exhaustive.
+}
+
  
 \subsection{ Rethrow}
 \label{rethrow}