boost/flyweight/assoc_container_factory.hpp

   1 /* Copyright 2006-2014 Joaquin M Lopez Munoz.
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * See http://www.boost.org/libs/flyweight for library home page.
   7  */
   8
   9 #ifndef BOOST_FLYWEIGHT_ASSOC_CONTAINER_FACTORY_HPP
  10 #define BOOST_FLYWEIGHT_ASSOC_CONTAINER_FACTORY_HPP
  11
  12 #if defined(_MSC_VER)
  13 #pragma once
  14 #endif
  15
  16 #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
  17 #include <boost/flyweight/assoc_container_factory_fwd.hpp>
  18 #include <boost/flyweight/detail/is_placeholder_expr.hpp>
  19 #include <boost/flyweight/detail/nested_xxx_if_not_ph.hpp>
  20 #include <boost/flyweight/factory_tag.hpp>
  21 #include <boost/mpl/apply.hpp>
  22 #include <boost/mpl/aux_/lambda_support.hpp>
  23 #include <boost/mpl/if.hpp>
  24
  25 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
  26 #include <utility>
  27 #endif
  28
  29 namespace boost{namespace flyweights{namespace detail{
  30 BOOST_FLYWEIGHT_NESTED_XXX_IF_NOT_PLACEHOLDER_EXPRESSION_DEF(iterator);
  31 BOOST_FLYWEIGHT_NESTED_XXX_IF_NOT_PLACEHOLDER_EXPRESSION_DEF(value_type);
  32 }}} /* namespace boost::flyweights::detail */
  33
  34 /* Factory class using a given associative container.
  35  */
  36
  37 namespace boost{
  38
  39 namespace flyweights{
  40
  41 template<typename Container>
  42 class assoc_container_factory_class:public factory_marker
  43 {
  44 public:
  45   /* When assoc_container_factory_class<Container> is an MPL placeholder
  46    * expression, referring to Container::iterator and Container::value_type
  47    * force the MPL placeholder expression Container to be instantiated, which
  48    * is wasteful and can fail in concept-checked STL implementations.
  49    * We protect ourselves against this circumstance.
  50    */
  51
  52   typedef typename detail::nested_iterator_if_not_placeholder_expression<
  53     Container
  54   >::type                                handle_type;
  55   typedef typename detail::nested_value_type_if_not_placeholder_expression<
  56     Container
  57   >::type                                entry_type;
  58
  59   handle_type insert(const entry_type& x)
  60   {
  61     return cont.insert(x).first;
  62   }
  63
  64 #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
  65   handle_type insert(entry_type&& x)
  66   {
  67     return cont.insert(std::move(x)).first;
  68   }
  69 #endif
  70
  71   void erase(handle_type h)
  72   {
  73     cont.erase(h);
  74   }
  75
  76   static const entry_type& entry(handle_type h){return *h;}
  77
  78 private:
  79   /* As above, avoid instantiating Container if it is an
  80    * MPL placeholder expression.
  81    */
  82
  83   typedef typename mpl::if_<
  84     detail::is_placeholder_expression<Container>,
  85     int,
  86     Container
  87   >::type container_type;
  88   container_type cont;
  89
  90 public:
  91   typedef assoc_container_factory_class type;
  92   BOOST_MPL_AUX_LAMBDA_SUPPORT(1,assoc_container_factory_class,(Container))
  93 };
  94
  95 /* assoc_container_factory_class specifier */
  96
  97 template<
  98   typename ContainerSpecifier
  99   BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION_DEF
 100 >
 101 struct assoc_container_factory:factory_marker
 102 {
 103   template<typename Entry,typename Key>
 104   struct apply
 105   {
 106     typedef assoc_container_factory_class<
 107       typename mpl::apply2<ContainerSpecifier,Entry,Key>::type
 108     > type;
 109   };
 110 };
 111
 112 }  /* namespace flyweights */
 113
 114 } /* namespace boost */
 115
 116 #endif