Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for a snapshot of the develop branch, built from commit 08e0dd6d5c.

libs/flyweight/test/test_assoc_cont_factory.cpp

/* Boost.Flyweight test of assoc_container_factory.
 *
 * Copyright 2006-2018 Joaquin M Lopez Munoz.
 * 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)
 *
 * See http://www.boost.org/libs/flyweight for library home page.
 */

#include "test_assoc_cont_factory.hpp"

#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
#include <boost/flyweight/assoc_container_factory.hpp> 
#include <boost/flyweight/detail/is_placeholder_expr.hpp>
#include <boost/flyweight/flyweight.hpp>
#include <boost/flyweight/refcounted.hpp>
#include <boost/flyweight/simple_locking.hpp>
#include <boost/flyweight/static_holder.hpp>
#include <boost/mpl/if.hpp>
#include <functional>
#include <set>
#include "test_basic_template.hpp"

using namespace boost::flyweights;

struct reverse_set_specifier
{
  template<typename Entry,typename Key>
  struct apply
  {
    typedef std::set<Entry,std::greater<Key> > type;
  };
};

struct assoc_container_factory_flyweight_specifier1
{
  template<typename T>
  struct apply
  {
    typedef flyweight<
      T,
      assoc_container_factory<reverse_set_specifier>
    > type;
  };
};

/* flyweight<..., assoc_container_factory_class<std::set<...> >, ...> pulls
 * the type std::set<...> in as part of its associated ADL set and causes it
 * to be instantiated when doing any unqualified function call like, for
 * instance, comparing flyweights for equality, which can trigger a static
 * assertion in concept-checked STL implementations when std::set<...> is an
 * MPL placeholder expression. We avoid this mess with protected_set<...>.
 */

struct protected_set_empty_base{};

template<typename K,typename C,typename A>
struct protected_set:
  boost::mpl::if_c<
    boost::flyweights::detail::is_placeholder_expression<
      protected_set<K,C,A>
    >::value,
    protected_set_empty_base,
    std::set<K,C,A>
  >::type
{};

struct assoc_container_factory_flyweight_specifier2
{
  template<typename T>
  struct apply
  {
    typedef flyweight<
      T,
      assoc_container_factory_class<
        protected_set<
          boost::mpl::_1,
          std::greater<boost::mpl::_2>,
          std::allocator<boost::mpl::_1>
        >
      >
    > type;
  };
};

void test_assoc_container_factory()
{
  test_basic_template<assoc_container_factory_flyweight_specifier1>();
  test_basic_template<assoc_container_factory_flyweight_specifier2>();
}