Allow streaming Class references.

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5524 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/io/BasicStreamers.java

@@ -44,6 +44,7 @@ public class BasicStreamers
         Long.class,
         Float.class,
         Double.class,
+        Class.class,
         String.class,
         boolean[].class,
         byte[].class,
@@ -68,6 +69,7 @@ public class BasicStreamers
         new LongStreamer(),
         new FloatStreamer(),
         new DoubleStreamer(),
+        new ClassStreamer(),
         new StringStreamer(),
         new BooleanArrayStreamer(),
         new ByteArrayStreamer(),
@@ -225,6 +227,24 @@ public class BasicStreamers
         }
     }
 
+    /** Streams {@link Class} instances. */
+    public static class ClassStreamer extends BasicStreamer
+    {
+        @Override
+        public Object createObject (ObjectInputStream in)
+            throws IOException, ClassNotFoundException
+        {
+            return in.readClassMapping().sclass;
+        }
+
+        @Override
+        public void writeObject (Object object, ObjectOutputStream out, boolean useWriter)
+            throws IOException
+        {
+            out.writeClassMapping((Class)object);
+        }
+    }
+
     /** Streams {@link String} instances. */
     public static class StringStreamer extends BasicStreamer
     {

src/java/com/threerings/io/ObjectInputStream.java

@@ -76,59 +76,14 @@ public class ObjectInputStream extends DataInputStream
     public Object readObject ()
         throws IOException, ClassNotFoundException
     {
-        ClassMapping cmap;
-
-        // create our classmap if necessary
-        if (_classmap == null) {
-            _classmap = new ArrayList<ClassMapping>();
-            // insert a zeroth element
-            _classmap.add(null);
-        }
-
         try {
-            // read in the class code for this instance
-            short code = readShort();
-
-            // a zero code indicates a null value
-            if (code == 0) {
+            // read the class mapping
+            ClassMapping cmap = readClassMapping();
+            if (cmap == null) {
                 if (STREAM_DEBUG) {
                     log.info(hashCode() + ": Read null.");
                 }
                 return null;
-
-            // if the code is negative, that means that we've never seen it before and class
-            // metadata follows
-            } else if (code < 0) {
-                // first swap the code into positive-land
-                code *= -1;
-
-                // read in the class metadata
-                String cname = readUTF();
-                // if we have a translation (used to cope when serialized classes are renamed) use
-                // it
-                if (_translations != null) {
-                    String tname = _translations.get(cname);
-                    if (tname != null) {
-                        cname = tname;
-                    }
-                }
-
-                // create the class mapping
-                cmap = mapClass(code, cname);
-
-            } else {
-                cmap = _classmap.get(code);
-
-                // sanity check
-                if (cmap == null) {
-                    // this will help with debugging
-                    log.warning("Internal stream error, no class metadata", "code", code,
-                                "ois", this, new Exception());
-                    log.warning("ObjectInputStream mappings", "map", _classmap);
-                    String errmsg = "Read object code for which we have no registered class " +
-                        "metadata [code=" + code + "]";
-                    throw new RuntimeException(errmsg);
-                }
             }
 
             if (STREAM_DEBUG) {
@@ -145,6 +100,65 @@ public class ObjectInputStream extends DataInputStream
         }
     }
 
+    /**
+     * Reads a class mapping from the stream.
+     *
+     * @return the class mapping, or <code>null</code> to represent a null value.
+     */
+    protected ClassMapping readClassMapping ()
+        throws IOException, ClassNotFoundException
+    {
+        // create our classmap if necessary
+        if (_classmap == null) {
+            _classmap = new ArrayList<ClassMapping>();
+            // insert a zeroth element
+            _classmap.add(null);
+        }
+
+        // read in the class code for this instance
+        short code = readShort();
+
+        // a zero code indicates a null value
+        if (code == 0) {
+            return null;
+
+        // if the code is negative, that means that we've never seen it before and class
+        // metadata follows
+        } else if (code < 0) {
+            // first swap the code into positive-land
+            code *= -1;
+
+            // read in the class metadata
+            String cname = readUTF();
+            // if we have a translation (used to cope when serialized classes are renamed) use
+            // it
+            if (_translations != null) {
+                String tname = _translations.get(cname);
+                if (tname != null) {
+                    cname = tname;
+                }
+            }
+
+            // create the class mapping
+            return mapClass(code, cname);
+
+        } else {
+            ClassMapping cmap = _classmap.get(code);
+
+            // sanity check
+            if (cmap == null) {
+                // this will help with debugging
+                log.warning("Internal stream error, no class metadata", "code", code,
+                            "ois", this, new Exception());
+                log.warning("ObjectInputStream mappings", "map", _classmap);
+                String errmsg = "Read object code for which we have no registered class " +
+                    "metadata [code=" + code + "]";
+                throw new RuntimeException(errmsg);
+            }
+            return cmap;
+        }
+    }
+
     /**
      * Creates, adds, and returns the class mapping for the specified code and class name.
      */

src/java/com/threerings/io/ObjectOutputStream.java

@@ -71,13 +71,25 @@ public class ObjectOutputStream extends DataOutputStream
             return;
         }
 
+        // otherwise, write the class mapping, then the bare object
+        Class<?> sclass = Streamer.getStreamerClass(object);
+        ClassMapping cmap = writeClassMapping(sclass);
+        writeBareObject(object, cmap.streamer, true);
+    }
+
+    /**
+     * Retrieves or creates the class mapping for the supplied class, writes it out to the stream,
+     * and returns a reference to it.
+     */
+    protected ClassMapping writeClassMapping (Class<?> sclass)
+        throws IOException
+    {
         // create our classmap if necessary
         if (_classmap == null) {
             _classmap = new HashMap<Class<?>, ClassMapping>();
         }
 
-        // otherwise, look up the class mapping record
-        Class<?> sclass = Streamer.getStreamerClass(object);
+        // look up the class mapping record
         ClassMapping cmap = _classmap.get(sclass);
 
         // create a class mapping for this class if we've not got one
@@ -103,8 +115,7 @@ public class ObjectOutputStream extends DataOutputStream
         } else {
             writeExistingClassMapping(cmap);
         }
-
-        writeBareObject(object, cmap.streamer, true);
+        return cmap;
     }
 
     /**