boost/flyweight/assoc_container_factory.hpp

   1 /* Copyright 2006-2009 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)&&(_MSC_VER>=1200)
  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 namespace boost{namespace flyweights{namespace detail{
  26 BOOST_FLYWEIGHT_NESTED_XXX_IF_NOT_PLACEHOLDER_EXPRESSION_DEF(iterator);
  27 BOOST_FLYWEIGHT_NESTED_XXX_IF_NOT_PLACEHOLDER_EXPRESSION_DEF(value_type);
  28 }}} /* namespace boost::flyweights::detail */
  29
  30 /* Factory class using a given associative container.
  31  */
  32
  33 namespace boost{
  34
  35 namespace flyweights{
  36
  37 template<typename Container>
  38 class assoc_container_factory_class:public factory_marker
  39 {
  40 public:
  41   /* When assoc_container_factory_class<Container> is an MPL placeholder
  42    * expression, referring to Container::iterator and Container::value_type
  43    * force the MPL placeholder expression Container to be instantiated, which
  44    * is wasteful and can fail in concept-checked STL implementations.
  45    * We protect ourselves against this circumstance.
  46    */
  47
  48   typedef typename detail::nested_iterator_if_not_placeholder_expression<
  49     Container
  50   >::type                                handle_type;
  51   typedef typename detail::nested_value_type_if_not_placeholder_expression<
  52     Container
  53   >::type                                entry_type;
  54
  55   handle_type insert(const entry_type& x)
  56   {
  57     return cont.insert(x).first;
  58   }
  59
  60   void erase(handle_type h)
  61   {
  62     cont.erase(h);
  63   }
  64
  65   static const entry_type& entry(handle_type h){return *h;}
  66
  67 private:
  68   /* As above, avoid instantiating Container if it is an
  69    * MPL placeholder expression.
  70    */
  71
  72   typedef typename mpl::if_<
  73     detail::is_placeholder_expression<Container>,
  74     int,
  75     Container
  76   >::type container_type;
  77   container_type cont;
  78
  79 public:
  80   typedef assoc_container_factory_class type;
  81   BOOST_MPL_AUX_LAMBDA_SUPPORT(1,assoc_container_factory_class,(Container))
  82 };
  83
  84 /* assoc_container_factory_class specifier */
  85
  86 template<
  87   typename ContainerSpecifier
  88   BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION_DEF
  89 >
  90 struct assoc_container_factory:factory_marker
  91 {
  92   template<typename Entry,typename Key>
  93   struct apply
  94   {
  95     typedef assoc_container_factory_class<
  96       typename mpl::apply2<ContainerSpecifier,Entry,Key>::type
  97     > type;
  98   };
  99 };
 100
 101 }  /* namespace flyweights */
 102
 103 } /* namespace boost */
 104
 105 #endif