summaryrefslogtreecommitdiff
path: root/boost/fusion/algorithm/transformation/detail/replace_if.hpp
diff options
context:
space:
mode:
Diffstat (limited to 'boost/fusion/algorithm/transformation/detail/replace_if.hpp')
-rw-r--r--boost/fusion/algorithm/transformation/detail/replace_if.hpp73
1 files changed, 73 insertions, 0 deletions
diff --git a/boost/fusion/algorithm/transformation/detail/replace_if.hpp b/boost/fusion/algorithm/transformation/detail/replace_if.hpp
new file mode 100644
index 0000000000..d45ca39219
--- /dev/null
+++ b/boost/fusion/algorithm/transformation/detail/replace_if.hpp
@@ -0,0 +1,73 @@
+/*=============================================================================
+ Copyright (c) 2001-2011 Joel de Guzman
+
+ Distributed under the Boost Software License, Version 1.0. (See accompanying
+ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+==============================================================================*/
+#if !defined(FUSION_REPLACE_IF_08182005_0946)
+#define FUSION_REPLACE_IF_08182005_0946
+
+#include <boost/utility/enable_if.hpp>
+#include <boost/mpl/if.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+namespace boost { namespace fusion { namespace detail
+{
+ template <bool is_convertible>
+ struct replacer_if_helper;
+
+ template <>
+ struct replacer_if_helper<false>
+ {
+ template <typename U, typename F, typename T>
+ static U&
+ call(U& x, F&, T const&)
+ {
+ return x;
+ }
+ };
+
+ template <>
+ struct replacer_if_helper<true>
+ {
+ template <typename U, typename F, typename T>
+ static U
+ call(U& x, F& f, T const& new_value)
+ {
+ return f(x) ? new_value : x;
+ }
+ };
+
+ template <typename F, typename T>
+ struct replacer_if
+ {
+ replacer_if(F in_f, T const& in_new_value)
+ : f(in_f), new_value(in_new_value) {}
+
+ template<typename Params>
+ struct result;
+
+ template <typename F1, typename T1, typename U>
+ struct result<replacer_if<F1, T1>(U)>
+ {
+ typedef typename remove_reference<U>::type value;
+ typedef typename
+ mpl::if_<is_convertible<T, value>, value, value const&>::type
+ type;
+ };
+
+ template <typename U>
+ typename result<replacer_if(U)>::type
+ operator()(U const& x) const
+ {
+ return replacer_if_helper<is_convertible<T, U>::value>::
+ call(x, f, new_value);
+ }
+
+ F f;
+ T new_value;
+ };
+}}}
+
+#endif
+