From d005ab4f8425f0d8797699f11c722726979a877e Mon Sep 17 00:00:00 2001
From: Geoff Berry <gcb@gnu.org>
Date: Tue, 7 Jul 1998 08:21:38 +0000
Subject: See ChangeLog.

---
 gnu/java/io/ObjectIdentityWrapper.java | 82 ++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 gnu/java/io/ObjectIdentityWrapper.java

(limited to 'gnu/java/io/ObjectIdentityWrapper.java')

diff --git a/gnu/java/io/ObjectIdentityWrapper.java b/gnu/java/io/ObjectIdentityWrapper.java
new file mode 100644
index 000000000..503930cbc
--- /dev/null
+++ b/gnu/java/io/ObjectIdentityWrapper.java
@@ -0,0 +1,82 @@
+/*************************************************************************
+/* ObjectIdentityWrapper.java -- Wrapper class used to override equals()
+/*                               and hashCode() to be as discriminating
+/*			         as possible
+/*
+/* Copyright (c) 1998 by Geoffrey C. Berry (gcb@cs.duke.edu)
+/*
+/* This program is free software; you can redistribute it and/or modify
+/* it under the terms of the GNU Library General Public License as published 
+/* by the Free Software Foundation, version 2. (see COPYING.LIB)
+/*
+/* This program is distributed in the hope that it will be useful, but
+/* WITHOUT ANY WARRANTY; without even the implied warranty of
+/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+/* GNU General Public License for more details.
+/*
+/* You should have received a copy of the GNU General Public License
+/* along with this program; if not, write to the Free Software Foundation
+/* Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307 USA
+/*************************************************************************/
+
+package gnu.java.io;
+
+/**
+   This class is a thin wrapper around <code>Object</code> that makes
+   the methods <code>hashCode()</code> and <code>equals(Object)</code>
+   as discriminating as possible.
+*/
+public class ObjectIdentityWrapper
+{
+
+  /**
+     Constructs a <code>ObjectIdentityWrapper</code> that is wrapped
+     around o.
+  */
+  public ObjectIdentityWrapper( Object o )
+  {
+    object = o;
+  }
+
+  /**
+     Uses <code>System.identityHashCode(Object)</code> to compute a
+     hash code for the object wrapped by this
+     <code>ObjectIdentityWrapper</code>.
+
+     @see java.lang.System#identityHashCode(java.lang.Object)
+     @see java.util.Hashtable
+     @see java.lang.Object#hashCode()
+  */
+  public int hashCode()
+  {
+    return System.identityHashCode( object );
+  }
+
+  /**
+     Uses the <code>==</code> operator to test for equality between
+     the object wrapped by this <code>ObjectIdentityWrapper</code> and
+     the object wrapped by the <code>ObjectIdentityWrapper</code> o.
+     Returns false if o is not a <code>ObjectIdentityWrapper</code>.
+
+     @see java.util.Hashtable
+     @see java.lang.Object#equals()
+  */
+  public boolean equals( Object o )
+  {
+    if( o instanceof ObjectIdentityWrapper )
+      return object == ((ObjectIdentityWrapper)o).object;
+    else
+      return false;
+  }
+
+  public String toString()
+  {
+    return "ObjectIdentityWrapper< " + object + ", " + hashCode() + " >";
+  }
+
+  /**
+     The <code>Object</code> wrapped by this
+     <code>ObjectIdentityWrapper</code>.
+  */
+  public Object object;
+}
-- 
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