1 files changed, 76 insertions, 0 deletions
diff --git a/dom/xul/nsForwardReference.h b/dom/xul/nsForwardReference.h
new file mode 100644
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+++ b/dom/xul/nsForwardReference.h
@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsForwardReference_h__
+#define nsForwardReference_h__
+
+class nsForwardReference
+{
+protected:
+    nsForwardReference() {}
+
+public:
+    virtual ~nsForwardReference() {}
+
+    /**
+     * Priority codes returned from GetPhase()
+     */
+    enum Phase {
+        /** A dummy marker, used to indicate unstarted resolution */
+        eStart,
+
+        /** The initial pass, after which the content model will be
+            fully built */
+        eConstruction,
+
+        /** A second pass, after which all 'magic attribute' hookup
+            will have been performed */
+        eHookup,
+
+        /** A dummy marker, used in kPasses to indicate termination */
+        eDone
+    };
+
+    /**
+     * Forward references are categorized by 'priority', and all
+     * forward references in a higher priority are resolved before any
+     * reference in a lower priority. This variable specifies this
+     * ordering. The last Priority is guaranteed to be eDone.
+     */
+    static const Phase kPasses[];
+
+    /**
+     * Get the state in which the forward reference should be resolved.
+     * 'eConstruction' references are all resolved before 'eHookup' references
+     * are resolved.
+     *
+     * @return the Phase in which the reference needs to be resolved
+     */
+    virtual Phase GetPhase() = 0;
+
+    /**
+     * Result codes returned from Resolve()
+     */
+    enum Result {
+        /** Resolution succeeded, I'm done. */
+        eResolve_Succeeded,
+
+        /** Couldn't resolve, but try me later. */
+        eResolve_Later,
+
+        /** Something bad happened, don't try again. */
+        eResolve_Error
+    };
+
+    /**
+     * Attempt to resolve the forward reference.
+     *
+     * @return a Result that tells the resolver how to treat
+     * the reference.
+     */
+    virtual Result Resolve() = 0;
+};
+
+#endif // nsForwardReference_h__