implement separate and virtual deletePropertyValue function, include in spec

Author: graydon

eval.sml

@@ -909,6 +909,58 @@ and defValue (regs:REGS)
     : unit =
     setPropertyValueOrVirtual regs base name v false
 
+
+and deletePropertyValueOrVirtual (regs:REGS)
+                                 (obj:OBJECT)
+                                 (name:NAME)
+                                 (doVirtual:bool)
+    : VALUE =
+    let
+        val Object { propertyMap, tag, ... } = obj
+        val existingProp = findProp propertyMap name
+    in
+        case existingProp of
+            SOME { attrs = { fixed = true, ...}, ...} 
+
+            => newBoolean regs false
+               
+          | _ 
+            => if 
+                doVirtual andalso 
+                Fixture.hasFixture (getFixtureMap regs obj) (PropName meta_delete)
+            then 
+                (trace ["running meta::delete(\"", (Ustring.toAscii (#id name)), (* INFORMATIVE *) 
+                        "\") catchall on obj #", fmtObjId obj]; (* INFORMATIVE *) 
+                 (* LPAREN *)(evalNamedMethodCall regs obj meta_delete [newString regs (#id name)])
+                  handle ThrowException e => 
+                         let
+                             val ty = typeOfVal regs e
+                             val defaultBehaviorClassTy = 
+                                 instanceType regs helper_DefaultBehaviorClass []
+                         in
+                             if ty <* defaultBehaviorClassTy then
+                                 deletePropertyValueOrVirtual regs obj name false
+                             else 
+                                 throwExn e
+                         end
+                )(* INFORMATIVE *)
+            else
+                case existingProp of 
+                    SOME { attrs = { removable = true, ... }, ... } 
+                    => (delProp propertyMap name;
+                        newBoolean regs true)
+                       
+                  | _ 
+                    => newBoolean regs false
+    end
+
+
+and deletePropertyValue (regs:REGS)
+                        (base:OBJECT)
+                        (name:NAME)
+    : VALUE =
+    deletePropertyValueOrVirtual regs base name true
+
 and instantiateGlobalClass (regs:REGS)
                            (n:NAME)
                            (args:VALUE list)
@@ -2796,13 +2848,9 @@ and evalUnaryOp (regs:REGS)
         case unop of
             Delete => 
             let
-                val (_, (Object {propertyMap, ...}, name)) = resolveRefExpr regs expr false
+                val (_, (obj, name)) = resolveRefExpr regs expr false
             in
-                if (hasProp propertyMap name)
-                then if (#removable (#attrs (getProp propertyMap name)))
-                     then (delProp propertyMap name; newBoolean regs true)
-                     else newBoolean regs false
-                else newBoolean regs true
+                deletePropertyValue regs obj name
             end
 
           | PreIncrement => evalCrement regs Plus true expr

name.sml

@@ -295,6 +295,7 @@ val meta_get = meta Ustring.get_
 val meta_set = meta Ustring.set_
 val meta_has = meta Ustring.has_
 val meta_call = meta Ustring.call_
+val meta_delete = meta Ustring.delete_
 
 val public_arguments = public Ustring.arguments_
 val helper_argsLength = helper Ustring.argsLength_

spec/language/readwrite.html

@@ -179,40 +179,9 @@
 phrase that was recognized in a region of code that was covered by a
 strict mode pragma.
 
-<FIXME> This protocol must be specified as SML code.
+
+<FIXME>Strict mode is not implemented in this code.
 
 <SEM>
-<PRE>
-fun DeleteProperty(obj, name, isStrict)
-  if (name is a property in the property map of obj, denote it obj.name &&
-      the fixed attribute of obj.name is true)
-    if isStrict
-      throw a ReferenceError, "can't delete fixture properties"
-    end
-    return false
-  end
-
-  if (meta::delete is a property in the property map of obj, 
-             denote it obj.meta::delete
-      && the fixed attribute of meta::delete is true)
-    try 
-      return obj.meta::delete(name)
-    catch DefaultBehavior
-      ; fall through to the next case
-    end
-  end
-  
-  if name is a property in the property map of obj, denote it obj.name
-    if the removable attribute of obj.name is true
-      remove obj.name from the property map of obj
-      return true
-    end
-
-    if isStrict
-      throw a ReferenceError, "can't delete non-removable property"
-    end
-  end
-
-  return false
-end
-</PRE>
+<INCLUDE file="eval.sml" name="and deletePropertyValue">
+<INCLUDE file="eval.sml" name="and deletePropertyValueOrVirtual">

ustring.sml

@@ -235,6 +235,7 @@ val has_                     = fromString "has"
 val call_                    = fromString "call"
 val get_                     = fromString "get"
 val set_                     = fromString "set"
+val delete_                  = fromString "delete"
 val slice_                   = fromString "slice"
 val objectHash_              = fromString "objectHash"
 val type_                    = fromString "type"