Passes: Support cown creation

src/lang/bytecode.h

@@ -9,6 +9,7 @@ inline const trieste::TokenDef StoreField{"store_field"};
 inline const trieste::TokenDef CreateObject{"create_object"};
 inline const trieste::TokenDef Proto{"prototype"};
 inline const trieste::TokenDef Dictionary{"dictionary"};
+inline const trieste::TokenDef Cown{"cown"};
 inline const trieste::TokenDef String{"string", trieste::flag::print};
 inline const trieste::TokenDef KeyIter{"key_iter"};
 inline const trieste::TokenDef Func{"func"};

src/lang/interpreter.cc

@@ -185,6 +185,12 @@ namespace verona::interpreter
             "CreateObject: A bytecode function requires a body node");
           obj = rt::make_func(new Bytecode{payload->at(0)});
         }
+        else if (payload == Cown)
+        {
+          auto v = pop("cown reagion");
+          obj = rt::make_cown(v);
+          rt::move_reference(frame(), obj, v);
+        }
         else
         {
           assert(false && "CreateObject has to specify a value");

src/lang/lang.h

@@ -32,7 +32,8 @@ inline const TokenDef Compile{"compile"};
 namespace verona::wf
 {
   inline const auto lv = Ident | Lookup;
-  inline const auto rv = lv | Empty | Null | String | Create | Call | Method;
+  inline const auto rv =
+    lv | Empty | Null | String | Create | Call | Method | Cown;
   inline const auto cmp_values = Ident | Lookup | Null;
   inline const auto key = Ident | Lookup | String;
   inline const auto operand = Lookup | Call | Method | Ident;
@@ -44,8 +45,8 @@ namespace verona::wf
       ReturnValue | Call | Method)++) |
     (Assign <<= (Lhs >>= lv) * (Rhs >>= rv)) |
     (Lookup <<= (Op >>= operand) * (Rhs >>= key)) | (Region <<= Ident) |
-    (Freeze <<= Ident) | (Taint <<= Ident) | (Create <<= Ident) |
-    (If <<= Eq * Block * Block) |
+    (Freeze <<= Ident) | (Taint <<= Ident) | (Cown <<= Ident) |
+    (Create <<= Ident) | (If <<= Eq * Block * Block) |
     (For <<= (Key >>= Ident) * (Value >>= Ident) * (Op >>= lv) * Block) |
     (Eq <<= (Lhs >>= cmp_values) * (Rhs >>= cmp_values)) |
     (Func <<= Ident * Params * Body) | (Call <<= Ident * List) |
@@ -58,13 +59,13 @@ namespace verona::wf
       CreateObject | CreateRegion | FreezeObject | Taint | IterNext | Print |
       Eq | Neq | Jump | JumpFalse | Label | Call | Return | ReturnValue |
       ClearStack | Dup)++) |
-    (CreateObject <<= (Dictionary | String | KeyIter | Proto | Func)) |
+    (CreateObject <<= (Dictionary | String | KeyIter | Proto | Func | Cown)) |
     (Func <<= Body) | (Label <<= Ident)[Ident];
 }
 
 inline const auto LV = T(Ident, Lookup);
 inline const auto RV =
-  T(Empty, Ident, Lookup, Null, String, Create, Call, Method);
+  T(Empty, Ident, Lookup, Null, String, Create, Call, Method, Cown);
 inline const auto CMP_V = T(Ident, Lookup, Null);
 inline const auto KEY = T(Ident, Lookup, String);
 inline const auto OPERAND = T(Lookup, Call, Method, Ident);

src/lang/passes/bytecode.cc

@@ -1,5 +1,7 @@
 #include "../lang.h"
 
+inline const trieste::TokenDef DestructiveRead{"destructive_read"};
+
 PassDef bytecode()
 {
   PassDef p{
@@ -79,6 +81,18 @@ PassDef bytecode()
           return Seq << (Compile << _[Ident]) << create_from(Taint, _(Op));
         },
 
+      T(Compile) << (T(DestructiveRead) << T(Ident)[Ident]) >>
+        [](auto& _) {
+          // Read the value from the frame and set the frame value to null
+          return Seq << (Compile << _(Ident)) << Null
+                     << create_from(StoreFrame, _(Ident));
+        },
+      T(Compile) << (T(Cown)[Op] << T(Ident)[Ident]) >>
+        [](auto& _) {
+          return Seq << (Compile << (DestructiveRead << _(Ident)))
+                     << (CreateObject << Cown);
+        },
+
       T(Compile) << (T(Create)[Op] << T(Ident)[Ident]) >>
         [](auto& _) {
           return Seq << (Compile << _[Ident]) << (CreateObject << Proto);

src/lang/passes/flatten.cc

@@ -14,8 +14,9 @@ namespace verona::wf
     (Func <<= Compile) | (Compile <<= Body) | (Create <<= Ident) |
     (Assign <<= (Lhs >>= lv) * (Rhs >>= rv)) |
     (Lookup <<= (Op >>= operand) * (Rhs >>= key)) | (Region <<= Ident) |
-    (Freeze <<= Ident) | (Taint <<= Ident) | (Call <<= Ident * List) |
-    (Method <<= Lookup * List) | (List <<= rv++) | (Params <<= Ident++) |
+    (Freeze <<= Ident) | (Taint <<= Ident) | (Cown <<= Ident) |
+    (Call <<= Ident * List) | (Method <<= Lookup * List) | (List <<= rv++) |
+    (Params <<= Ident++) |
     (Eq <<= (Lhs >>= cmp_values) * (Rhs >>= cmp_values)) |
     (Neq <<= (Lhs >>= cmp_values) * (Rhs >>= cmp_values)) |
     (Label <<= Ident)[Ident];

src/lang/passes/grouping.cc

@@ -16,22 +16,12 @@ PassDef grouping()
       In(Group) * OPERAND[Op] * (T(Lookup)[Lookup] << (T(Group) << KEY[Rhs])) >>
         [](auto& _) { return Lookup << _(Op) << _(Rhs); },
 
-      T(Group) << ((T(Region)[Region] << End) * T(Ident)[Ident] * End) >>
-        [](auto& _) {
-          _(Region)->extend(_(Ident)->location());
-          return _(Region) << _(Ident);
-        },
-
-      T(Group) << ((T(Freeze)[Freeze] << End) * T(Ident)[Ident] * End) >>
-        [](auto& _) {
-          _(Freeze)->extend(_(Ident)->location());
-          return _(Freeze) << _(Ident);
-        },
-
-      T(Group) << ((T(Taint)[Taint] << End) * T(Ident)[Ident] * End) >>
+      T(Group)
+          << ((T(Freeze, Taint, Cown, Region)[Op] << End) * T(Ident)[Ident] *
+              End) >>
         [](auto& _) {
-          _(Taint)->extend(_(Ident)->location());
-          return _(Taint) << _(Ident);
+          _(Op)->extend(_(Ident)->location());
+          return _(Op) << _(Ident);
         },
 
       T(Group) << ((T(Drop)[Drop] << End) * LV[Lhs] * End) >>

src/lang/passes/parse.cc

@@ -5,7 +5,7 @@ namespace verona::wf
   using namespace trieste::wf;
 
   inline const auto parse_tokens = Region | Ident | Lookup | Empty | Freeze |
-    Drop | Taint | Null | String | Create | Parens;
+    Taint | Cown | Drop | Null | String | Create | Parens;
   inline const auto parse_groups =
     Group | Assign | If | Else | Block | For | Func | List | Return;
 
@@ -154,8 +154,9 @@ trieste::Parse parser()
       "drop" >> [](auto& m) { m.add(Drop); },
       "create" >> [](auto& m) { m.add(Create); },
       "freeze" >> [](auto& m) { m.add(Freeze); },
-      "region" >> [](auto& m) { m.add(Region); },
       "taint" >> [](auto& m) { m.add(Taint); },
+      "cown" >> [](auto& m) { m.add(Cown); },
+      "region" >> [](auto& m) { m.add(Region); },
       "None" >> [](auto& m) { m.add(Null); },
       "[0-9A-Za-z_]+" >> [](auto& m) { m.add(Ident); },
       "\\[" >> [](auto& m) { m.push(Lookup); },

src/rt/core.h

@@ -189,7 +189,7 @@ namespace rt::core
 
   public:
     CownObject(objects::DynObject* region)
-    : objects::DynObject(cownPrototypeObject()),
+    : objects::DynObject(cownPrototypeObject())
     {
       // FIXME: Add once regions are reified
       // assert(
@@ -218,7 +218,7 @@ namespace rt::core
 
     bool is_cown() override
     {
-      return false;
+      return true;
     }
   };
 

src/rt/objects/dyn_object.h

@@ -79,8 +79,11 @@ namespace rt::objects
         return;
       }
 
-      assert(target->parent == src);
-      Region::dec_prc(target);
+      if (src)
+      {
+        assert(target->parent == src);
+        Region::dec_prc(target);
+      }
       return;
     }
 
@@ -234,7 +237,7 @@ namespace rt::objects
       // TODO SCC algorithm
       visit(this, [](Edge e) {
         auto obj = e.target;
-        if (obj->is_immutable())
+        if (!obj || obj->is_immutable())
           return false;
 
         auto r = get_region(obj);
@@ -244,7 +247,8 @@ namespace rt::objects
         }
         obj->region.set_tag(ImmutableTag);
 
-        return !obj->is_cown();
+        auto cown = obj->is_cown();
+        return !cown;
       });
     }
 

tests/valid_cowns.vpy

@@ -0,0 +1,21 @@
+global = {}
+
+# A simple cown
+a = {}
+a.b = {}
+region a
+c01 = cown a
+
+# Store the cown in a global
+global.cown = c01
+taint global
+
+# Freeze global with a cown
+freeze global
+
+# FIXME: traint with cowns is wrong
+# FIXME: Show local region address
+# FIXME: Cowns should have special rendering and out edges
+
+drop c01
+drop global