Reapply "Allow LetCont to bind multiple continuations."

tests/compiler/dart2js/backend_dart/sexpr_unstringifier.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // SExpressionUnstringifier implements the inverse operation to
 // [SExpressionStringifier].
 
 library sexpr_unstringifier;
 
 import 'package:compiler/src/constants/expressions.dart'
@@ skipping 107 matching lines @@
   static const String CONCATENATE_STRINGS = "ConcatenateStrings";
   static const String DECLARE_FUNCTION = "DeclareFunction";
   static const String INVOKE_CONSTRUCTOR = "InvokeConstructor";
   static const String INVOKE_CONTINUATION = "InvokeContinuation";
   static const String INVOKE_CONTINUATION_RECURSIVE = "InvokeContinuation*";
   static const String INVOKE_STATIC = "InvokeStatic";
   static const String INVOKE_SUPER_METHOD = "InvokeSuperMethod";
   static const String INVOKE_METHOD = "InvokeMethod";
   static const String LET_PRIM = "LetPrim";
   static const String LET_CONT = "LetCont";
-  static const String LET_CONT_RECURSIVE = "LetCont*";
   static const String SET_CLOSURE_VARIABLE = "SetClosureVariable";
   static const String TYPE_OPERATOR = "TypeOperator";
 
   // Primitives
   static const String CONSTANT = "Constant";
   static const String CREATE_FUNCTION = "CreateFunction";
   static const String GET_CLOSURE_VARIABLE = "GetClosureVariable";
   static const String LITERAL_LIST = "LiteralList";
   static const String LITERAL_MAP = "LiteralMap";
   static const String REIFY_TYPE_VAR = "ReifyTypeVar";
@@ skipping 87 matching lines @@
         return parseInvokeContinuation(true);
       case INVOKE_METHOD:
         return parseInvokeMethod();
       case INVOKE_STATIC:
         return parseInvokeStatic();
       case INVOKE_SUPER_METHOD:
         return parseInvokeSuperMethod();
       case LET_PRIM:
         return parseLetPrim();
       case LET_CONT:
-        return parseLetCont(false);
-      case LET_CONT_RECURSIVE:
-        return parseLetCont(true);
+        return parseLetCont();
       case SET_CLOSURE_VARIABLE:
         return parseSetClosureVariable();
       case TYPE_OPERATOR:
         return parseTypeOperator();
       default:
         assert(false);
     }
 
     return null;
   }
@@ skipping 201 matching lines @@
     List<Primitive> args = parsePrimitiveList();
 
     Continuation cont = name2variable[tokens.read()];
     assert(cont != null);
 
     tokens.consumeEnd();
     Selector selector = dummySelector(methodName, args.length);
     return new InvokeSuperMethod(selector, cont, args);
   }
 
-  /// (LetCont (name (args) cont_body) body)
-  LetCont parseLetCont(bool recursive) {
-    tokens.consumeStart(recursive ? LET_CONT_RECURSIVE : LET_CONT);
-
-    // (name
+  // (rec? name (args) body)
+  Continuation parseContinuation() {
+    // (rec? name
     tokens.consumeStart();
     String name = tokens.read();
+    bool isRecursive = name == "rec";
+    if (isRecursive) name = tokens.read();
 
     // (args)
     tokens.consumeStart();
     List<Parameter> params = <Parameter>[];
     while (tokens.current != ")") {
       String paramName = tokens.read();
       Parameter param = new Parameter(new DummyElement(paramName));
       name2variable[paramName] = param;
       params.add(param);
     }
     tokens.consumeEnd();
 
     Continuation cont = new Continuation(params);
     name2variable[name] = cont;
 
-    cont.isRecursive = recursive;
+    cont.isRecursive = isRecursive;
     // cont_body
     cont.body = parseExpression();
     tokens.consumeEnd();
+    return cont;
+  }
+
+  /// (LetCont (continuations) body)
+  LetCont parseLetCont() {
+    tokens.consumeStart(LET_CONT);
+    tokens.consumeStart();
+    List<Continuation> continuations = <Continuation>[];
+    while (tokens.current != ")") {
+      continuations.add(parseContinuation());
+    }
+    tokens.consumeEnd();
 
     // body)
     Expression body = parseExpression();
     tokens.consumeEnd();
 
-    return new LetCont(cont, body);
+    return new LetCont(continuations, body);
   }
 
   /// (SetClosureVariable name value body)
   SetClosureVariable parseSetClosureVariable() {
     tokens.consumeStart(SET_CLOSURE_VARIABLE);
 
     ClosureVariable local = name2variable[tokens.read()];
     Primitive value = name2variable[tokens.read()];
     assert(value != null);
 
@@ skipping 179 matching lines @@
     return new ReifyTypeVar(type);
   }
 
   /// (This)
   This parseThis() {
     tokens.consumeStart(THIS);
     tokens.consumeEnd();
     return new This();
   }
 }