1 
2 #ifndef BOOST_MPL_COPY_IF_HPP_INCLUDED
3 #define BOOST_MPL_COPY_IF_HPP_INCLUDED
4 
5 // Copyright Aleksey Gurtovoy 2000-2004
6 // Copyright David Abrahams 2003-2004
7 //
8 // Distributed under the Boost Software License, Version 1.0.
9 // (See accompanying file LICENSE_1_0.txt or copy at
10 // http://www.boost.org/LICENSE_1_0.txt)
11 //
12 // See http://www.boost.org/libs/mpl for documentation.
13 
14 // $Id$
15 // $Date$
16 // $Revision$
17 
18 #include <boost/mpl/fold.hpp>
19 #include <boost/mpl/reverse_fold.hpp>
20 #include <boost/mpl/apply.hpp>
21 #include <boost/mpl/eval_if.hpp>
22 #include <boost/mpl/identity.hpp>
23 #include <boost/mpl/protect.hpp>
24 #include <boost/mpl/aux_/inserter_algorithm.hpp>
25 #include <boost/mpl/aux_/config/forwarding.hpp>
26 
27 namespace boost { namespace mpl {
28 
29 namespace aux {
30 
31 template<
32       typename Operation
33     , typename Predicate
34     >
35 struct copy_if_op
36 {
37     template< typename Sequence, typename T > struct apply
38 #if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)
39         : eval_if<
40               typename apply1<Predicate,T>::type
41             , apply2<Operation,Sequence,T>
42             , identity<Sequence>
43             >
44     {
45 #else
46     {
47         typedef typename eval_if<
48               typename apply1<Predicate,T>::type
49             , apply2<Operation,Sequence,T>
50             , identity<Sequence>
51             >::type type;
52 #endif
53     };
54 };
55 
56 template<
57       typename Sequence
58     , typename Predicate
59     , typename Inserter
60     >
61 struct copy_if_impl
62     : fold<
63           Sequence
64         , typename Inserter::state
65         , protect< aux::copy_if_op<
66               typename Inserter::operation
67             , Predicate
68             > >
69         >
70 {
71 };
72 
73 template<
74       typename Sequence
75     , typename Predicate
76     , typename Inserter
77     >
78 struct reverse_copy_if_impl
79     : reverse_fold<
80           Sequence
81         , typename Inserter::state
82         , protect< aux::copy_if_op<
83               typename Inserter::operation
84             , Predicate
85             > >
86         >
87 {
88 };
89 
90 } // namespace aux
91 
92 BOOST_MPL_AUX_INSERTER_ALGORITHM_DEF(3, copy_if)
93 
94 }}
95 
96 #endif // BOOST_MPL_COPY_IF_HPP_INCLUDED
97