New object streaming code is born!

git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@1605 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/io/ArrayMask.java

@@ -0,0 +1,73 @@
+//
+// $Id: ArrayMask.java,v 1.1 2002/07/23 05:42:34 mdb Exp $
+
+package com.threerings.io;
+
+import java.io.IOException;
+
+/**
+ * Used to keep track of which entries in an array are null and which are
+ * not. <em>Note:</em> only arrays up to 262,144 elements in length can be
+ * handled by this class.
+ */
+public class ArrayMask
+{
+    /**
+     * Creates an array mask suitable for unserializing.
+     */
+    public ArrayMask ()
+    {
+    }
+
+    /**
+     * Creates an array mask for an array of the specified length.
+     */
+    public ArrayMask (int length)
+    {
+        int mlength = length/8;
+        if (length % 8 != 0) {
+            mlength++;
+        }
+        _mask = new byte[mlength];
+    }
+
+    /**
+     * Sets the bit indicating that the specified array index is non-null.
+     */
+    public void set (int index)
+    {
+        _mask[index/8] |= (1 << (index%8));
+    }
+
+    /**
+     * Returns true if the specified array index should be non-null.
+     */
+    public boolean isSet (int index)
+    {
+        return (_mask[index/8] & (1 << (index%8))) != 0;
+    }
+
+    /**
+     * Writes this mask to the specified output stream.
+     */
+    public void writeTo (ObjectOutputStream out)
+        throws IOException
+    {
+        out.writeShort(_mask.length);
+        out.write(_mask);
+    }
+
+    /**
+     * Reads this mask from the specified input stream.
+     */
+    public void readFrom (ObjectInputStream in)
+        throws IOException
+    {
+        int length = in.readShort();
+        _mask = new byte[length];
+        in.read(_mask);
+    }
+
+    /** A byte array with bits for every entry in the source array. */
+    protected byte[] _mask;
+}