boost/utility.hpp:

- Include boost/utility/addressof.hpp

boost/utility/addressof.hpp:
  - addressof() implementation

libs/utility/utility.htm:
  - Document addressof

libs/utility/addressof_test.cpp:
  - Test addressof()


[SVN r13414]

addressof_test.cpp

@@ -0,0 +1,46 @@
+// Copyright (C) 2002 Brad King (brad.king@kitware.com) 
+//                    Doug Gregor (gregod@cs.rpi.edu)
+//
+// Permission to copy, use, sell and distribute this software is granted
+// provided this copyright notice appears in all copies.
+// Permission to modify the code and to distribute modified code is granted
+// provided this copyright notice appears in all copies, and a notice
+// that the code was modified is included with the copyright notice.
+//
+// This software is provided "as is" without express or implied warranty,
+// and with no claim as to its suitability for any purpose.
+
+// For more information, see http://www.boost.org
+
+#define BOOST_INCLUDE_MAIN
+#include <boost/test/test_tools.hpp>
+#include <boost/utility.hpp>
+
+struct useless_type {};
+
+class nonaddressable {
+public:
+  void dummy(); // Silence GCC warning: all member of class are private
+
+private:
+  useless_type operator&() const;
+};
+
+int test_main(int, char*[])
+{
+  nonaddressable* px = new nonaddressable();
+
+  nonaddressable& x = *px;
+  BOOST_TEST(boost::addressof(x) == px);
+
+  const nonaddressable& cx = *px;
+  BOOST_TEST(boost::addressof(cx) == static_cast<const nonaddressable*>(px));
+
+  volatile nonaddressable& vx = *px;
+  BOOST_TEST(boost::addressof(vx) == static_cast<volatile nonaddressable*>(px));
+
+  const volatile nonaddressable& cvx = *px;
+  BOOST_TEST(boost::addressof(cvx) == static_cast<const volatile nonaddressable*>(px));
+  
+  return 0;
+}

include/boost/utility.hpp

@@ -17,6 +17,7 @@
 
 #include <boost/checked_delete.hpp>
 #include <boost/utility/base_from_member.hpp>  
+#include <boost/utility/addressof.hpp>
 
 namespace boost
 {

include/boost/utility/addressof.hpp

@@ -0,0 +1,53 @@
+// Copyright (C) 2002 Brad King (brad.king@kitware.com) 
+//                    Doug Gregor (gregod@cs.rpi.edu)
+//
+// Permission to copy, use, sell and distribute this software is granted
+// provided this copyright notice appears in all copies.
+// Permission to modify the code and to distribute modified code is granted
+// provided this copyright notice appears in all copies, and a notice
+// that the code was modified is included with the copyright notice.
+//
+// This software is provided "as is" without express or implied warranty,
+// and with no claim as to its suitability for any purpose.
+
+// For more information, see http://www.boost.org
+
+#ifndef BOOST_UTILITY_ADDRESSOF_HPP
+#define BOOST_UTILITY_ADDRESSOF_HPP
+
+namespace boost {
+
+template <typename T>
+inline T* addressof(T& v)
+{
+  struct addressof_helper {};
+  return reinterpret_cast<T*>(&reinterpret_cast<addressof_helper&>(v));
+}
+
+template <typename T>
+inline const T* addressof(const T& v)
+{
+  struct addressof_helper {};
+  return reinterpret_cast<const T*>(
+           &reinterpret_cast<const addressof_helper&>(v));
+}
+
+template <typename T>
+inline volatile T* addressof(volatile T& v)
+{
+  struct addressof_helper {};
+  return reinterpret_cast<volatile T*>(
+           &reinterpret_cast<volatile addressof_helper&>(v));
+}
+
+template <typename T>
+inline const volatile T* addressof(const volatile T& v)
+{
+  struct addressof_helper {};
+  return reinterpret_cast<const volatile T*>(
+           &reinterpret_cast<const volatile addressof_helper&>(v));
+}
+
+}
+
+#endif // BOOST_UTILITY_ADDRESSOF_HPP

utility.htm

@@ -22,6 +22,7 @@
     checked_array_delete()</a></li>
   <li>Function templates <a href="#functions next">next() and prior()</a></li>
   <li>Class <a href="#Class noncopyable">noncopyable</a></li>
+  <li>Function template <a href="#addressof">addressof()</a></li>
   <li>Function template <a href="tie.html">tie()</a> and supporting class tied.</li>
 </ul>
 <h2> Function templates <a name="checked_delete">checked_delete</a>() and
@@ -133,6 +134,48 @@ emphasize that it is to be used only as a base class.&nbsp; Dave Abrahams notes
 concern about the effect on compiler optimization of adding (even trivial inline)
 destructor declarations. He says &quot;Probably this concern is misplaced, because
 noncopyable will be used mostly for classes which own resources and thus have non-trivial destruction semantics.&quot;</p>
+<h2><a name="addressof">Function template addressof()</a></h2>
+<p>Function <strong>addressof()</strong> returns the address of an object.</p>
+
+<blockquote>
+<pre>
+template &lt;typename T&gt; inline T*                addressof(T& v);
+template &lt;typename T&gt; inline const T*          addressof(const T& v);
+template &lt;typename T&gt; inline volatile T*       addressof(volatile T& v);
+template &lt;typename T&gt; inline const volatile T* addressof(const volatile T& v);
+</pre>
+</blockquote>
+
+
+<p>C++ allows programmers to replace the unary
+<strong>operator&()</strong> class member used to get the address of
+an object.  Getting the real address of an object requires ugly
+casting tricks to avoid invoking the overloaded
+<strong>operator&()</strong>.  Function <strong>addressof()</strong>
+provides a wrapper around the necessary code to make it easy to get an
+object's real address.
+</p>
+
+<p>The program <a href="addressof_test.cpp">addressof_test.cpp</a> can be
+used to verify that <b>addressof()</b> works as expected.</p>
+
+<p>Contributed by Brad King based on ideas from discussion with Doug Gregor.</p>
+<h3>Example</h3>
+<blockquote>
+<pre>#include &lt;boost/utility.hpp&gt;
+
+struct useless_type {};
+class nonaddressable {
+  useless_type operator&() const;
+};
+
+void f() {
+  nonaddressable x;
+  nonaddressable* xp = boost::addressof(x);
+  // nonaddressable* xpe = &amp;x; /* error */
+}</pre>
+</blockquote>
+
 <h2>Class templates for the Base-from-Member Idiom</h2>
 <p>See <a href="base_from_member.html">separate documentation</a>.</p>
 <h2>Function template tie()</h2>