make fewer assumptions about exported items, falsy values can now be exported

Author: luite

jsbits/export.js

@@ -1,24 +1,26 @@
 function h$exportValue(fp1a,fp1b,fp2a,fp2b,o) {
-    var e = { fp1a: fp1a
-            , fp1b: fp1b
-            , fp2a: fp2a
-            , fp2b: fp2b
-            , root: o
-	        , _key: -1
-            };
-    h$retain(e);
-    return e;
+  var e = { fp1a: fp1a
+          , fp1b: fp1b
+          , fp2a: fp2a
+          , fp2b: fp2b
+          , released: false
+          , root: o
+          , _key: -1
+          };
+  h$retain(e);
+  return e;
 }
 
 function h$derefExport(fp1a,fp1b,fp2a,fp2b,e) {
-    if(!e || typeof e !== 'object') return null;
-    if(!e.root) return null;
-    if(fp1a !== e.fp1a || fp1b !== e.fp1b ||
-       fp2a !== e.fp2a || fp2b !== e.fp2b) return null;
-    return e.root;
+  if(!e || typeof e !== 'object') return null;
+  if(e.released) return null;
+  if(fp1a !== e.fp1a || fp1b !== e.fp1b ||
+     fp2a !== e.fp2a || fp2b !== e.fp2b) return null;
+  return e.root;
 }
 
 function h$releaseExport(e) {
-    h$release(e);
-    e.root = null;
+  h$release(e);
+  e.released = true;
+  e.root     = null;
 }