boost/boost/signals/detail/slot_call_iterator.hpp

   1 // Boost.Signals library
   2
   3 // Copyright Doug Gregor 2001-2003. 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 <functional>
  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
  19 #ifdef BOOST_HAS_ABI_HEADERS
  20 #  include BOOST_ABI_PREFIX
  21 #endif
  22
  23 namespace boost {
  24   namespace BOOST_SIGNALS_NAMESPACE {
  25     namespace detail {
  26       // A cached return value from a slot
  27       template<typename T>
  28       struct cached_return_value {
  29         cached_return_value(const T& t) : value(t) {}
  30
  31         T value;
  32       };
  33
  34       // Generates a slot call iterator. Essentially, this is an iterator that:
  35       //   - skips over disconnected slots in the underlying list
  36       //   - calls the connected slots when dereferenced
  37       //   - caches the result of calling the slots
  38       template<typename Function, typename Iterator>
  39       class slot_call_iterator
  40         : public iterator_facade<slot_call_iterator<Function, Iterator>,
  41                                  typename Function::result_type,
  42                                  single_pass_traversal_tag,
  43                                  typename Function::result_type const&>
  44       {
  45         typedef iterator_facade<slot_call_iterator<Function, Iterator>,
  46                                 typename Function::result_type,
  47                                 single_pass_traversal_tag,
  48                                 typename Function::result_type const&>
  49           inherited;
  50
  51         typedef typename Function::result_type result_type;
  52
  53         friend class iterator_core_access;
  54
  55       public:
  56         slot_call_iterator() {}
  57
  58         slot_call_iterator(Iterator iter_in, Iterator end_in, Function f)
  59           : iter(iter_in), end(end_in), f(f), cache()
  60         {
  61           iter = std::find_if(iter, end, std::not1(is_disconnected()));
  62         }
  63
  64         typename inherited::reference
  65         dereference() const
  66         {
  67           if (!cache.get()) {
  68             cache.reset(new cached_return_value<result_type>(f(*iter)));
  69           }
  70
  71           return cache->value;
  72         }
  73
  74         void increment()
  75         {
  76           iter = std::find_if(++iter, end, std::not1(is_disconnected()));
  77           cache.reset();
  78         }
  79
  80         bool equal(const slot_call_iterator& other) const
  81         {
  82           iter = std::find_if(iter, end, std::not1(is_disconnected()));
  83           other.iter = std::find_if(other.iter, other.end,
  84                                     std::not1(is_disconnected()));
  85           return iter == other.iter;
  86         }
  87
  88       private:
  89         mutable Iterator iter;
  90         Iterator end;
  91         Function f;
  92         mutable shared_ptr< cached_return_value<result_type> > cache;
  93       };
  94     } // end namespace detail
  95   } // end namespace BOOST_SIGNALS_NAMESPACE
  96 } // end namespace boost
  97
  98 #ifdef BOOST_HAS_ABI_HEADERS
  99 #  include BOOST_ABI_SUFFIX
 100 #endif
 101
 102 #endif // BOOST_SIGNALS_SLOT_CALL_ITERATOR