boost/boost/signals/detail/slot_call_iterator.hpp

   1 // Boost.Signals library
   2
   3 // Copyright Douglas Gregor 2001-2004. Use, modification and
   4 // distribution is subject to the Boost Software License, Version
   5 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   6 // http://www.boost.org/LICENSE_1_0.txt)
   7
   8 // For more information, see http://www.boost.org
   9
  10 #ifndef BOOST_SIGNALS_SLOT_CALL_ITERATOR
  11 #define BOOST_SIGNALS_SLOT_CALL_ITERATOR
  12
  13 #include <memory>
  14 #include <boost/iterator/iterator_facade.hpp>
  15 #include <boost/smart_ptr.hpp>
  16 #include <boost/signals/detail/config.hpp>
  17 #include <boost/signals/connection.hpp>
  18 #include <boost/optional.hpp>
  19
  20 #ifdef BOOST_HAS_ABI_HEADERS
  21 #  include BOOST_ABI_PREFIX
  22 #endif
  23
  24 namespace boost {
  25   namespace BOOST_SIGNALS_NAMESPACE {
  26     namespace detail {
  27
  28       // Generates a slot call iterator. Essentially, this is an iterator that:
  29       //   - skips over disconnected slots in the underlying list
  30       //   - calls the connected slots when dereferenced
  31       //   - caches the result of calling the slots
  32       template<typename Function, typename Iterator>
  33       class slot_call_iterator
  34         : public iterator_facade<slot_call_iterator<Function, Iterator>,
  35                                  typename Function::result_type,
  36                                  single_pass_traversal_tag,
  37                                  typename Function::result_type const&>
  38       {
  39         typedef iterator_facade<slot_call_iterator<Function, Iterator>,
  40                                 typename Function::result_type,
  41                                 single_pass_traversal_tag,
  42                                 typename Function::result_type const&>
  43           inherited;
  44
  45         typedef typename Function::result_type result_type;
  46
  47         friend class iterator_core_access;
  48
  49       public:
  50         slot_call_iterator(Iterator iter_in, Iterator end_in, Function f,
  51                            optional<result_type> &c)
  52           : iter(iter_in), end(end_in), f(f), cache(&c)
  53         {
  54           iter = std::find_if(iter, end, is_callable());
  55         }
  56
  57         typename inherited::reference
  58         dereference() const
  59         {
  60           if (!cache->is_initialized()) {
  61             cache->reset(f(*iter));
  62           }
  63
  64           return cache->get();
  65         }
  66
  67         void increment()
  68         {
  69           iter = std::find_if(++iter, end, is_callable());
  70           cache->reset();
  71         }
  72
  73         bool equal(const slot_call_iterator& other) const
  74         {
  75           iter = std::find_if(iter, end, is_callable());
  76           other.iter = std::find_if(other.iter, other.end,
  77                                     is_callable());
  78           return iter == other.iter;
  79         }
  80
  81       private:
  82         mutable Iterator iter;
  83         Iterator end;
  84         Function f;
  85         optional<result_type>* cache;
  86       };
  87     } // end namespace detail
  88   } // end namespace BOOST_SIGNALS_NAMESPACE
  89 } // end namespace boost
  90
  91 #ifdef BOOST_HAS_ABI_HEADERS
  92 #  include BOOST_ABI_SUFFIX
  93 #endif
  94
  95 #endif // BOOST_SIGNALS_SLOT_CALL_ITERATOR