Use common API to extract value associated with top scope prototype chain

not to duplicate code

js/rhino/src/org/mozilla/javascript/ClassCache.java

@@ -81,21 +81,13 @@ public class ClassCache
      */
     public static ClassCache get(Scriptable scope)
     {
-        scope = ScriptableObject.getTopLevelScope(scope);
-        Scriptable obj = scope;
-        do {
-            if (obj instanceof ScriptableObject) {
-                ScriptableObject so = (ScriptableObject)obj;
-                ClassCache lc = (ClassCache)so.getAssociatedValue(AKEY);
-                if (lc != null) {
-                    return lc;
-                }
-            }
-            obj = obj.getPrototype();
-        } while (obj != null);
-
-        // ALERT: warn somehow about wrong cache usage ?
-        return new ClassCache();
+        ClassCache cache;
+        cache = (ClassCache)ScriptableObject.getTopScopeValue(scope, AKEY);
+        if (cache == null) {
+            // XXX warn somehow about wrong cache usage ?
+            cache = new ClassCache();
+        }
+        return cache;
     }
 
     /**

js/rhino/src/org/mozilla/javascript/ScriptRuntime.java

@@ -114,6 +114,7 @@ public class ScriptRuntime {
     };
 
     private static final Object LIBRARY_SCOPE_KEY = new Object();
+    private static final Object CONTEXT_FACTORY_KEY = new Object();
 
     public static ScriptableObject initStandardObjects(Context cx,
                                                        ScriptableObject scope,
@@ -122,7 +123,7 @@ public class ScriptRuntime {
         if (scope == null) {
             scope = new NativeObject();
         }
-        scope.associateValue(LIBRARY_SCOPE_KEY, LIBRARY_SCOPE_KEY);
+        scope.associateValue(LIBRARY_SCOPE_KEY, scope);
 
         (new ClassCache()).associate(scope);
 
@@ -170,17 +171,13 @@ public class ScriptRuntime {
 
     public static ScriptableObject getLibraryScope(Scriptable scope)
     {
-        scope = ScriptableObject.getTopLevelScope(scope);
-        do {
-            if (scope instanceof ScriptableObject) {
-                ScriptableObject so = (ScriptableObject)scope;
-                if (null != so.getAssociatedValue(LIBRARY_SCOPE_KEY)) {
-                    return so;
-                }
-            }
-            scope = scope.getPrototype();
-        } while (scope != null);
-        throw new IllegalStateException("Failed to find library scope");
+        ScriptableObject libScope;
+        libScope = (ScriptableObject)ScriptableObject.
+                       getTopScopeValue(scope, LIBRARY_SCOPE_KEY);
+        if (libScope == null) {
+            throw new IllegalStateException("Failed to find library scope");
+        }
+        return libScope;
     }
 
     public static Boolean wrapBoolean(boolean b)

js/rhino/src/org/mozilla/javascript/ScriptableObject.java

@@ -1551,6 +1551,35 @@ public abstract class ScriptableObject implements Scriptable, Serializable,
         return h.get(key);
     }
 
+    /**
+     * Get arbitrary application-specific value associated with the top scope
+     * of the given scope.
+     * The method first calls {@link #getTopLevelScope(Scriptable scope)}
+     * and then searches the prototype chain of the top scope for the first
+     * object containing the associated value with the given key.
+     *
+     * @param scope the starting scope.
+     * @param key key object to select particular value.
+     * @see #getAssociatedValue(Object key)
+     */
+    public static Object getTopScopeValue(Scriptable scope, Object key)
+    {
+        scope = ScriptableObject.getTopLevelScope(scope);
+        for (;;) {
+            if (scope instanceof ScriptableObject) {
+                ScriptableObject so = (ScriptableObject)scope;
+                Object value = so.getAssociatedValue(key);
+                if (value != null) {
+                    return value;
+                }
+            }
+            scope = scope.getPrototype();
+            if (scope == null) {
+                return null;
+            }
+        }
+    }
+
     /**
      * Associate arbitrary application-specific value with this object.
      * Value can only be associated with the given object and key only once.