Moved shared_container_iterator.hpp in iterator directory, modernized code.

shared_container_iterator now uses std::shared_ptr to store the reference
to the container. boost::shared_ptr is still supported and is wrapped
into std::shared_ptr on construction, so there is overhead due to allocation
of std::shared_ptr state. Going forward, std::shared_ptr is expected
to be the primary use case. As a bonus, this eliminates the dependency
on Boost.SmartPtr.

Moved shared_container_iterator.hpp into the iterator directory and left
a forwarding header for backward compatibility.

CMakeLists.txt

@@ -22,7 +22,6 @@ target_link_libraries(boost_iterator
         Boost::fusion
         Boost::mpl
         Boost::optional
-        Boost::smart_ptr
         Boost::type_traits
         Boost::utility
 )

build.jam

@@ -14,7 +14,6 @@ constant boost_dependencies :
     /boost/fusion//boost_fusion
     /boost/mpl//boost_mpl
     /boost/optional//boost_optional
-    /boost/smart_ptr//boost_smart_ptr
     /boost/type_traits//boost_type_traits
     /boost/utility//boost_utility ;
 

doc/index.html

@@ -140,7 +140,7 @@ sequence, rearranged according to some sequence of integer indices.</li>
 bidirectional sequence in reverse.  Corrects many of the
 shortcomings of C++98's <tt class="docutils literal"><span class="pre">std::reverse_iterator</span></tt>.</li>
 <li><a class="reference external" href="../../utility/shared_container_iterator.html"><tt class="docutils literal"><span class="pre">shared_container_iterator</span></tt></a>: an iterator over elements of a container whose
-lifetime is maintained by a <a class="reference external" href="../../smart_ptr/shared_ptr.htm"><tt class="docutils literal"><span class="pre">shared_ptr</span></tt></a> stored in the iterator.</li>
+lifetime is maintained by a <tt class="docutils literal"><span class="pre">shared_ptr</span></tt> stored in the iterator.</li>
 <li><a class="reference external" href="transform_iterator.html"><tt class="docutils literal"><span class="pre">transform_iterator</span></tt></a> (<a class="reference external" href="transform_iterator.pdf">PDF</a>): an iterator over elements which are the result of
 applying some functional transformation to the elements of an
 underlying sequence.  This component also replaces the old

doc/quickbook/shared_container_iterator.qbk

@@ -1,6 +1,6 @@
 [section:shared_container Shared Container Iterator]
 
-Defined in header [@../../../boost/shared_container_iterator.hpp `boost/shared_container_iterator.hpp`].
+Defined in header [@../../../boost/iterator/shared_container_iterator.hpp `boost/iterator/shared_container_iterator.hpp`].
 
 The purpose of the shared container iterator is to attach the lifetime
 of a container to the lifetime of its iterators. In other words, the
@@ -24,9 +24,22 @@ iterator.
 [h2 Synopsis]
 
   namespace boost {
+  namespace iterators {
     template <typename Container>
     class shared_container_iterator;
 
+    template <typename Container>
+    shared_container_iterator<Container>
+    make_shared_container_iterator(typename Container::iterator base,
+      std::shared_ptr<Container> const& container);
+
+    std::pair<
+      typename shared_container_iterator<Container>,
+      typename shared_container_iterator<Container>
+    >
+    make_shared_container_range(std::shared_ptr<Container> const& container);
+
+    // Backward compatibility with boost::shared_ptr
     template <typename Container>
     shared_container_iterator<Container>
     make_shared_container_iterator(typename Container::iterator base,
@@ -38,6 +51,15 @@ iterator.
     >
     make_shared_container_range(boost::shared_ptr<Container> const& container);
   }
+  }
+
+[note `shared_container_iterator` and its factory functions support both
+`std::shared_ptr` and `boost::shared_ptr` for a smart pointer that holds
+a shared reference to the container. However, the support for `boost::shared_ptr`
+comes at a cost of wrapping it in a `std::shared_ptr` internally. This means
+that when constructing the iterator from a `boost::shared_ptr`, the construction
+will have to allocate memory for `std::shared_ptr` shared state, which may
+potentially fail. It is recommended to use `std::shared_ptr` directly.]
 
 [section:shared_container_type The Shared Container Iterator Type]
 
@@ -57,18 +79,17 @@ the underlying vector and thereby extend the container's lifetime.
 
 [example_link shared_iterator_example1.cpp..`shared_iterator_example1.cpp`]:
 
-  #include "shared_container_iterator.hpp"
-  #include "boost/shared_ptr.hpp"
+  #include <boost/iterator/shared_container_iterator.hpp>
   #include <algorithm>
   #include <iostream>
   #include <vector>
+  #include <memory>
 
-  typedef boost::shared_container_iterator< std::vector<int> > iterator;
+  using iterator = boost::iterators::shared_container_iterator< std::vector<int> >;
 
 
-  void set_range(iterator& i, iterator& end)  {
-
-    boost::shared_ptr< std::vector<int> > ints(new std::vector<int>());
+  void set_range(iterator& i, iterator& end) {
+    std::shared_ptr< std::vector<int> > ints(new std::vector<int>());
 
     ints->push_back(0);
     ints->push_back(1);
@@ -77,18 +98,17 @@ the underlying vector and thereby extend the container's lifetime.
     ints->push_back(4);
     ints->push_back(5);
 
-    i = iterator(ints->begin(),ints);
-    end = iterator(ints->end(),ints);
+    i = iterator(ints->begin(), ints);
+    end = iterator(ints->end(), ints);
   }
 
 
   int main() {
+    iterator i, end;
 
-    iterator i,end;
+    set_range(i, end);
 
-    set_range(i,end);
-
-    std::copy(i,end,std::ostream_iterator<int>(std::cout,","));
+    std::copy(i, end, std::ostream_iterator<int>(std::cout, ","));
     std::cout.put('\n');
 
     return 0;
@@ -116,8 +136,12 @@ The `shared_container_iterator` type implements the member functions
 and operators required of the
 [@http://www.sgi.com/tech/stl/RandomAccessIterator.html Random Access
 Iterator] concept, though only operations defined for the base
-iterator will be valid. In addition it has the following constructor:
+iterator will be valid. In addition it has the following constructors:
 
+  shared_container_iterator(Container::iterator const& it,
+                            std::shared_ptr<Container> const& container)
+
+  // Backward compatibility with boost::shared_ptr
   shared_container_iterator(Container::iterator const& it,
                             boost::shared_ptr<Container> const& container)
 
@@ -125,6 +149,12 @@ iterator will be valid. In addition it has the following constructor:
 
 [section:shared_container_object_generator The Shared Container Iterator Object Generator]
 
+  template <typename Container>
+  shared_container_iterator<Container>
+  make_shared_container_iterator(Container::iterator base,
+                                 std::shared_ptr<Container> const& container)
+
+  // Backward compatibility with boost::shared_ptr
   template <typename Container>
   shared_container_iterator<Container>
   make_shared_container_iterator(Container::iterator base,
@@ -142,25 +172,23 @@ uses `make_shared_container_iterator()` to create the iterators.
 
 [example_link shared_iterator_example2.cpp..`shared_iterator_example2.cpp`]:
 
-  #include "shared_container_iterator.hpp"
-  #include "boost/shared_ptr.hpp"
+  #include <boost/iterator/shared_container_iterator.hpp>
   #include <algorithm>
   #include <iterator>
   #include <iostream>
   #include <vector>
+  #include <memory>
 
 
   template <typename Iterator>
-  void print_range_nl (Iterator begin, Iterator end) {
-    typedef typename std::iterator_traits<Iterator>::value_type val;
-    std::copy(begin,end,std::ostream_iterator<val>(std::cout,","));
+  void print_range_nl(Iterator begin, Iterator end) {
+    using val = typename std::iterator_traits<Iterator>::value_type;
+    std::copy(begin, end, std::ostream_iterator<val>(std::cout, ","));
     std::cout.put('\n');
   }
 
-
   int main() {
-
-    typedef boost::shared_ptr< std::vector<int> > ints_t;
+    using ints_t = std::shared_ptr< std::vector<int> >;
     {
       ints_t ints(new std::vector<int>());
 
@@ -171,12 +199,10 @@ uses `make_shared_container_iterator()` to create the iterators.
       ints->push_back(4);
       ints->push_back(5);
 
-      print_range_nl(boost::make_shared_container_iterator(ints->begin(),ints),
-                     boost::make_shared_container_iterator(ints->end(),ints));
+      print_range_nl(boost::iterators::make_shared_container_iterator(ints->begin(), ints),
+                     boost::iterators::make_shared_container_iterator(ints->end(), ints));
     }
 
-
-
     return 0;
   }
 
@@ -187,53 +213,61 @@ named. The output from this example is the same as the previous.
 
 [section:shared_container_generator The Shared Container Iterator Range Generator]
 
+  template <typename Container>
+  std::pair<
+    shared_container_iterator<Container>,
+    shared_container_iterator<Container>
+  >
+  make_shared_container_range(std::shared_ptr<Container> const& container);
+
+  // Backward compatibility with boost::shared_ptr
   template <typename Container>
   std::pair<
     shared_container_iterator<Container>,
     shared_container_iterator<Container>
   >
   make_shared_container_range(boost::shared_ptr<Container> const& container);
-  Class shared_container_iterator is meant primarily to return, using iterators, a range of values that we can guarantee will be alive as long as the iterators are. This is a convenience function to do just that. It is equivalent to
-  std::make_pair(make_shared_container_iterator(container->begin(),container),
-                 make_shared_container_iterator(container->end(),container));
+
+Class `shared_container_iterator` is meant primarily to return, using iterators,
+a range of values that we can guarantee will be alive as long as the iterators are.
+This is a convenience function to do just that. It is functionally equivalent to this:
+
+  std::make_pair(make_shared_container_iterator(container->begin(), container),
+                 make_shared_container_iterator(container->end(), container));
 
 [h2 Example]
 
-In the following example, a range of values is returned as a pair of shared_container_iterator objects.
+In the following example, a range of values is returned as a pair of `shared_container_iterator` objects.
 
 [example_link shared_iterator_example3.cpp..`shared_iterator_example3.cpp`]:
 
-  #include "shared_container_iterator.hpp"
-  #include "boost/shared_ptr.hpp"
-  #include "boost/tuple/tuple.hpp" // for boost::tie
-  #include <algorithm>              // for std::copy
+  #include <boost/iterator/shared_container_iterator.hpp>
+  #include <algorithm>     // for std::copy
   #include <iostream>
   #include <vector>
+  #include <memory>
+  #include <tuple>         // for std::tie
 
 
-  typedef boost::shared_container_iterator< std::vector<int> > iterator;
+  using iterator = boost::iterators::shared_container_iterator< std::vector<int> >;
 
-  std::pair<iterator,iterator>
+  std::pair<iterator, iterator>
   return_range() {
-    boost::shared_ptr< std::vector<int> > range(new std::vector<int>());
+    std::shared_ptr< std::vector<int> > range(new std::vector<int>());
     range->push_back(0);
     range->push_back(1);
     range->push_back(2);
     range->push_back(3);
     range->push_back(4);
     range->push_back(5);
-    return boost::make_shared_container_range(range);
+    return boost::iterators::make_shared_container_range(range);
   }
 
-
   int main() {
-
-
     iterator i,end;
+    std::tie(i, end) = return_range();
 
-    boost::tie(i,end) = return_range();
-
-    std::copy(i,end,std::ostream_iterator<int>(std::cout,","));
+    std::copy(i, end, std::ostream_iterator<int>(std::cout, ","));
     std::cout.put('\n');
 
     return 0;

include/boost/iterator/shared_container_iterator.hpp

@@ -0,0 +1,117 @@
+// (C) Copyright Ronald Garcia 2002. Permission to copy, use, modify, sell and
+// distribute this software is granted provided this copyright notice appears
+// in all copies. This software is provided "as is" without express or implied
+// warranty, and with no claim as to its suitability for any purpose.
+
+// See http://www.boost.org/libs/utility/shared_container_iterator.html for documentation.
+
+#ifndef BOOST_ITERATOR_SHARED_CONTAINER_ITERATOR_HPP_INCLUDED_
+#define BOOST_ITERATOR_SHARED_CONTAINER_ITERATOR_HPP_INCLUDED_
+
+#include <memory>
+#include <utility>
+#include <boost/iterator/iterator_adaptor.hpp>
+
+namespace boost {
+
+// For backward compatibility with boost::shared_ptr
+template< class T >
+class shared_ptr;
+
+namespace iterators {
+namespace detail {
+
+// Fake deleter that holds an instance of boost::shared_ptr and through it keeps the pointed object from deletion
+template< typename T >
+class shared_container_iterator_bsptr_holder
+{
+private:
+    boost::shared_ptr< T > m_ptr;
+
+public:
+    explicit shared_container_iterator_bsptr_holder(boost::shared_ptr< T > const& ptr) :
+        m_ptr(ptr)
+    {}
+
+    void operator()(T*) const noexcept {}
+};
+
+} // namespace detail
+
+template< typename Container >
+class shared_container_iterator :
+    public iterator_adaptor<
+        shared_container_iterator< Container >,
+        typename Container::iterator
+    >
+{
+private:
+    using super_t = iterator_adaptor<
+        shared_container_iterator< Container >,
+        typename Container::iterator
+    >;
+
+    using iterator_t = typename Container::iterator;
+    using container_ref_t = std::shared_ptr< Container >;
+
+public:
+    shared_container_iterator() = default;
+
+    shared_container_iterator(iterator_t const& x, container_ref_t const& c) :
+        super_t(x),
+        m_container_ref(c)
+    {}
+
+    // Constructor for backward compatibility with boost::shared_ptr
+    shared_container_iterator(iterator_t const& x, boost::shared_ptr< Container > const& c) :
+        super_t(x),
+        m_container_ref(c.get(), detail::shared_container_iterator_bsptr_holder< Container >(c))
+    {}
+
+private:
+    container_ref_t m_container_ref;
+};
+
+template< typename Container >
+inline shared_container_iterator< Container >
+make_shared_container_iterator(typename Container::iterator iter, std::shared_ptr< Container > const& container)
+{
+    return shared_container_iterator< Container >(iter, container);
+}
+
+template< typename Container >
+inline std::pair< shared_container_iterator< Container >, shared_container_iterator< Container > >
+make_shared_container_range(std::shared_ptr< Container > const& container)
+{
+    return std::make_pair
+    (
+        iterators::make_shared_container_iterator(container->begin(), container),
+        iterators::make_shared_container_iterator(container->end(), container)
+    );
+}
+
+// Factory functions for backward compatibility with boost::shared_ptr
+template< typename Container >
+inline shared_container_iterator< Container >
+make_shared_container_iterator(typename Container::iterator iter, boost::shared_ptr< Container > const& container)
+{
+    return shared_container_iterator< Container >(iter, container);
+}
+
+template< typename Container >
+inline std::pair< shared_container_iterator< Container >, shared_container_iterator< Container > >
+make_shared_container_range(boost::shared_ptr< Container > const& container)
+{
+    std::shared_ptr< Container > c(container.get(), detail::shared_container_iterator_bsptr_holder< Container >(container));
+    return iterators::make_shared_container_range(std::move(c));
+}
+
+} // namespace iterators
+
+using iterators::shared_container_iterator;
+using iterators::make_shared_container_iterator;
+using iterators::make_shared_container_range;
+
+} // namespace boost
+
+#endif // BOOST_ITERATOR_SHARED_CONTAINER_ITERATOR_HPP_INCLUDED_

include/boost/shared_container_iterator.hpp

@@ -1,69 +1,14 @@
-// (C) Copyright Ronald Garcia 2002. Permission to copy, use, modify, sell and
-// distribute this software is granted provided this copyright notice appears
-// in all copies. This software is provided "as is" without express or implied
-// warranty, and with no claim as to its suitability for any purpose.
-
-// See http://www.boost.org/libs/utility/shared_container_iterator.html for documentation.
+// (C) Copyright Andrey Semashev 2025.
+// Distributed under the Boost Software License, Version 1.0. (See
+// accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt)
 
 #ifndef BOOST_SHARED_CONTAINER_ITERATOR_HPP
 #define BOOST_SHARED_CONTAINER_ITERATOR_HPP
 
-#include "boost/iterator_adaptors.hpp"
-#include "boost/shared_ptr.hpp"
-#include <utility>
+// This is a deprecated header left for backward compatibility.
+// Please use <boost/iterator/shared_container_iterator.hpp> instead.
 
-namespace boost {
-namespace iterators {
+#include <boost/iterator/shared_container_iterator.hpp>
 
-template <typename Container>
-class shared_container_iterator : public iterator_adaptor<
-                                    shared_container_iterator<Container>,
-                                    typename Container::iterator> {
-
-  typedef iterator_adaptor<
-    shared_container_iterator<Container>,
-    typename Container::iterator> super_t;
-
-  typedef typename Container::iterator iterator_t;
-  typedef boost::shared_ptr<Container> container_ref_t;
-
-  container_ref_t container_ref;
-public:
-  shared_container_iterator() { }
-
-  shared_container_iterator(iterator_t const& x,container_ref_t const& c) :
-    super_t(x), container_ref(c) { }
-
-
-};
-
-template <typename Container>
-inline shared_container_iterator<Container>
-make_shared_container_iterator(typename Container::iterator iter,
-                               boost::shared_ptr<Container> const& container) {
-  typedef shared_container_iterator<Container> iterator;
-  return iterator(iter,container);
-}
-
-
-
-template <typename Container>
-inline std::pair<
-  shared_container_iterator<Container>,
-  shared_container_iterator<Container> >
-make_shared_container_range(boost::shared_ptr<Container> const& container) {
-  return
-    std::make_pair(
-      make_shared_container_iterator(container->begin(),container),
-      make_shared_container_iterator(container->end(),container));
-}
-
-} // namespace iterators
-
-using iterators::shared_container_iterator;
-using iterators::make_shared_container_iterator;
-using iterators::make_shared_container_range;
-
-} // namespace boost
-
-#endif
+#endif // BOOST_SHARED_CONTAINER_ITERATOR_HPP

test/Jamfile.v2

@@ -74,5 +74,5 @@ test-suite iterator
     [ compile adl_test.cpp : <library>/boost/array//boost_array ]
     [ compile range_distance_compat_test.cpp : <library>/boost/range//boost_range ]
 
-    [ run shared_iterator_test.cpp ]
+    [ run shared_iterator_test.cpp : : : <library>/boost/smart_ptr//boost_smart_ptr ]
 ;

test/shared_iterator_test.cpp

@@ -14,12 +14,14 @@
 //
 
 
-#include "boost/shared_container_iterator.hpp"
-#include "boost/shared_ptr.hpp"
+#include <boost/iterator/shared_container_iterator.hpp>
+#include <boost/shared_ptr.hpp>
 #include <boost/core/lightweight_test.hpp>
 #include <vector>
+#include <memory>
 
-struct resource {
+struct resource
+{
   static int count;
   resource() { ++count; }
   resource(resource const&) { ++count; }
@@ -27,20 +29,20 @@ struct resource {
 };
 int resource::count = 0;
 
-typedef std::vector<resource> resources_t;
+typedef std::vector< resource > resources_t;
 
 typedef boost::shared_container_iterator< resources_t > iterator;
 
-
-void set_range(iterator& i, iterator& end)  {
-
-  boost::shared_ptr< resources_t > objs(new resources_t());
+template< typename SharedPtr >
+void set_range(iterator& i, iterator& end)
+{
+  SharedPtr objs(new resources_t());
 
   for (int j = 0; j != 6; ++j)
     objs->push_back(resource());
 
-  i = iterator(objs->begin(),objs);
-  end = iterator(objs->end(),objs);
+  i = iterator(objs->begin(), objs);
+  end = iterator(objs->end(), objs);
   BOOST_TEST_EQ(resource::count, 6);
 }
 
@@ -53,7 +55,18 @@ int main() {
     iterator i;
     {
       iterator end;
-      set_range(i,end);
+      set_range< boost::shared_ptr< resources_t > >(i, end);
+      BOOST_TEST_EQ(resource::count, 6);
+    }
+    BOOST_TEST_EQ(resource::count, 6);
+  }
+  BOOST_TEST_EQ(resource::count, 0);
+
+  {
+    iterator i;
+    {
+      iterator end;
+      set_range< std::shared_ptr< resources_t > >(i, end);
       BOOST_TEST_EQ(resource::count, 6);
     }
     BOOST_TEST_EQ(resource::count, 6);

test/test_cmake/main.cpp

@@ -7,7 +7,6 @@
 #include <boost/indirect_reference.hpp>
 #include <boost/next_prior.hpp>
 #include <boost/pointee.hpp>
-#include <boost/shared_container_iterator.hpp>
 #include <boost/iterator/advance.hpp>
 #include <boost/iterator/counting_iterator.hpp>
 #include <boost/iterator/distance.hpp>
@@ -31,6 +30,7 @@
 #include <boost/iterator/new_iterator_tests.hpp>
 #include <boost/iterator/permutation_iterator.hpp>
 #include <boost/iterator/reverse_iterator.hpp>
+#include <boost/iterator/shared_container_iterator.hpp>
 #include <boost/iterator/transform_iterator.hpp>
 #include <boost/iterator/zip_iterator.hpp>