1 ////////////////////////////////////////////////////////////////////
2 //
3 // Copyright Vicente J. Botet Escriba 2010
4 //
5 // Distributed under the Boost Software License, Version 1.0.
6 // (See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
8 //
9 // See http://www.boost.org/libs/mpl for documentation.
10 //
11 ////////////////////////////////////////////////////////////////////
12 #ifndef BOOST_MPL_ABS_HPP_INCLUDED
13 #define BOOST_MPL_ABS_HPP_INCLUDED
14 
15 #include <boost/mpl/integral_c.hpp>
16 #include <boost/mpl/aux_/na_spec.hpp>
17 #include <boost/mpl/aux_/lambda_support.hpp>
18 #include <boost/mpl/aux_/config/integral.hpp>
19 #include <boost/mpl/aux_/config/static_constant.hpp>
20 
21 #if    !defined(BOOST_MPL_CFG_NO_NESTED_VALUE_ARITHMETIC_2) \
22     && !defined(BOOST_MPL_PREPROCESSING_MODE) \
23     && !defined(__CUDACC__) \
24     && ( defined(BOOST_MSVC) \
25         || BOOST_WORKAROUND(__EDG_VERSION__, <= 238) \
26         )
27 
28 #   define BOOST_MPL_CFG_NO_NESTED_VALUE_ARITHMETIC_2
29 
30 #endif
31 
32 namespace boost { namespace mpl {
33 
34 template< typename Tag > struct abs_impl;
35 
36 template< typename T > struct abs_tag
37 {
38     typedef typename T::tag type;
39 };
40 
41 template<
42       typename BOOST_MPL_AUX_NA_PARAM(N)
43     >
44 struct abs
45     : abs_impl<
46           typename abs_tag<N>::type
47         >::template apply<N>::type
48 {
49     BOOST_MPL_AUX_LAMBDA_SUPPORT(1, abs, (N))
50 };
51 
52 BOOST_MPL_AUX_NA_SPEC(1, abs)
53 
54 template<
55       typename T
56     , T n1
57     >
58 struct abs_c
59     : abs<integral_c<T,n1> >
60 {
61 };
62 
63 #if defined(BOOST_MPL_CFG_NO_NESTED_VALUE_ARITHMETIC_2)
64 namespace aux {
65 template< typename T, T n > struct abs_wknd
66 {
67     BOOST_STATIC_CONSTANT(T, value = (n < 0 ? -n : n));
68     typedef integral_c<T,value> type;
69 };
70 }
71 #endif
72 
73 template<>
74 struct abs_impl<integral_c_tag>
75 {
76 #if defined(BOOST_MPL_CFG_NO_NESTED_VALUE_ARITHMETIC_2)
77     template< typename N > struct apply
78         : aux::abs_wknd< typename N::value_type, N::value >
79 #else
80     template< typename N > struct apply
81         : integral_c< typename N::value_type, ((N::value < 0) ? (-N::value) : N::value ) >
82 #endif
83     {
84     };
85 };
86 
87 }}
88 
89 #endif // BOOST_MPL_ABS_HPP_INCLUDED
90