From 3f0ebd4c71f99cd373657afb330842845cc3d7a9 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Mon, 22 Jul 2002 16:36:52 +0000
Subject: [PATCH] 'shared_from_this' added.

[SVN r14561]
---
 include/boost/shared_ptr.hpp | 22 ++++++++++++++++++++++
 shared_ptr_test.cpp          | 27 ++++++++++++++++++++++++++-
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/include/boost/shared_ptr.hpp b/include/boost/shared_ptr.hpp
index 28a6286..bea9e11 100644
--- a/include/boost/shared_ptr.hpp
+++ b/include/boost/shared_ptr.hpp
@@ -313,6 +313,28 @@ template<typename T> inline T * get_pointer(shared_ptr<T> const & p)
     return p.get();
 }
 
+// shared_from_this() creates a shared_ptr from a raw pointer (usually 'this')
+
+namespace detail
+{
+
+inline void sp_assert_counted_base(boost::counted_base const *)
+{
+}
+
+template<class T> inline T * sp_remove_const(T const * p)
+{
+    return const_cast<T *>(p);
+}
+
+} // namespace detail
+
+template<class T> shared_ptr<T> shared_from_this(T * p)
+{
+    detail::sp_assert_counted_base(p);
+    return shared_ptr<T>(detail::sp_remove_const(p));
+}
+
 } // namespace boost
 
 #ifdef BOOST_MSVC
diff --git a/shared_ptr_test.cpp b/shared_ptr_test.cpp
index f96dfc6..6113d26 100644
--- a/shared_ptr_test.cpp
+++ b/shared_ptr_test.cpp
@@ -112,6 +112,16 @@ public:
         std::cout << "Z(" << this << ")::~Z()\n";
     }
 
+	boost::shared_ptr<Z> shared_this()
+	{
+		return boost::shared_from_this(this);
+	}
+
+	boost::shared_ptr<Z const> shared_this() const
+	{
+		return boost::shared_from_this(this);
+	}
+
 private:
 
     Z(Z const &);
@@ -331,9 +341,24 @@ int test_main(int, char * [])
 
         {
             // test intrusive counting
-            boost::shared_ptr<void> pv(new Z);
+
+			boost::shared_ptr<void> pv(new Z);
             boost::shared_ptr<Z> pz = boost::shared_static_cast<Z>(pv);
             BOOST_TEST(pz.use_count() == pz->use_count());
+
+			// test shared_from_this
+
+			boost::shared_ptr<Z> pz2 = pz->shared_this();
+
+			Z const & z = *pz2;
+
+			boost::shared_ptr<Z const> pz3 = z.shared_this();
+
+			BOOST_TEST(pz.use_count() == pz->use_count());
+			BOOST_TEST(pz2.use_count() == pz2->use_count());
+			BOOST_TEST(pz3.use_count() == pz3->use_count());
+			BOOST_TEST(pz.use_count() == pz2.use_count());
+			BOOST_TEST(pz.use_count() == pz3.use_count());
         }
     }