ceph/src/boost/libs/property_map/include/boost/property_map/parallel/basic_reduce.hpp

   1 // Copyright 2005 The Trustees of Indiana University.
   2
   3 // Use, modification and distribution is subject to the Boost Software
   4 // License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 //  Authors: Douglas Gregor
   8 //           Andrew Lumsdaine
   9
  10 #ifndef BOOST_PARALLEL_BASIC_REDUCE_HPP
  11 #define BOOST_PARALLEL_BASIC_REDUCE_HPP
  12
  13 namespace boost { namespace parallel {
  14
  15 /** Reduction operation used to reconcile differences between local
  16  * and remote values for a particular key in a property map.  The
  17  * type @c T is typically the @c value_type of the property
  18  * map. This basic reduction returns a default-constructed @c T as
  19  * the default value and always resolves to the remote value.
  20  */
  21 template<typename T>
  22 struct basic_reduce
  23 {
  24   BOOST_STATIC_CONSTANT(bool, non_default_resolver = false);
  25
  26   /// Returns a default-constructed T object
  27   template<typename Key>
  28   T operator()(const Key&) const { return T(); }
  29
  30   /// Returns the remote value
  31   template<typename Key>
  32   const T& operator()(const Key&, const T&, const T& remote) const
  33   { return remote; }
  34 };
  35
  36 } } // end namespace boost::parallel
  37
  38 #endif // BOOST_PARALLEL_BASIC_REDUCE_HPP