Use Boost.Variant instead of GIL's own variant implementation (#231)

Adds support C++11 decltype(auto)

Fixes #131

.appveyor.yml

@@ -94,6 +94,7 @@ before_build:
   - git submodule --quiet update --init libs/preprocessor
   - git submodule --quiet update --init libs/test
   - git submodule --quiet update --init libs/type_traits
+  - git submodule --quiet update --init libs/variant
   ## Transitive (of GIL tests too)
   - git submodule --quiet update --init libs/atomic
   - git submodule --quiet update --init libs/bind

.travis.yml

@@ -213,6 +213,7 @@ install:
   - git submodule --quiet update --init libs/preprocessor
   - git submodule --quiet update --init libs/test
   - git submodule --quiet update --init libs/type_traits
+  - git submodule --quiet update --init libs/variant
   ## Transitive (of GIL tests too)
   - git submodule --quiet update --init libs/atomic
   - git submodule --quiet update --init libs/bind

include/boost/gil/extension/dynamic_image/any_image.hpp

@@ -9,6 +9,7 @@
 #define BOOST_GIL_EXTENSION_DYNAMIC_IMAGE_ANY_IMAGE_HPP
 
 #include <boost/gil/extension/dynamic_image/any_image_view.hpp>
+#include <boost/gil/extension/dynamic_image/apply_operation.hpp>
 
 #include <boost/gil/image.hpp>
 
@@ -63,8 +64,8 @@ namespace detail {
 /// In particular, its \p view and \p const_view methods return \p any_image_view, which does not fully model ImageViewConcept. See \p any_image_view for more.
 ////////////////////////////////////////////////////////////////////////////////////////
 template <typename ImageTypes>
-class any_image : public variant<ImageTypes> {
-    using parent_t = variant<ImageTypes>;
+class any_image : public make_variant_over<ImageTypes>::type {
+    using parent_t = typename make_variant_over<ImageTypes>::type;
 public:
     using const_view_t = any_image_view<typename detail::images_get_const_views_t<ImageTypes>::type>;
     using view_t = any_image_view<typename detail::images_get_views_t<ImageTypes>::type>;
@@ -76,11 +77,11 @@ class any_image : public variant<ImageTypes> {
     template <typename T> explicit any_image(const T& obj)               : parent_t(obj) {}
     template <typename T> explicit any_image(T& obj, bool do_swap)       : parent_t(obj,do_swap) {}
     any_image(const any_image& v)                                        : parent_t((const parent_t&)v)    {}
-    template <typename Types> any_image(const any_image<Types>& v)       : parent_t((const variant<Types>&)v)    {}
+    template <typename Types> any_image(const any_image<Types>& v)       : parent_t((const typename make_variant_over<Types>::type&)v)    {}
 
     template <typename T> any_image& operator=(const T& obj)                  { parent_t::operator=(obj); return *this; }
     any_image&                       operator=(const any_image& v)            { parent_t::operator=((const parent_t&)v); return *this;}
-    template <typename Types> any_image& operator=(const any_image<Types>& v) { parent_t::operator=((const variant<Types>&)v); return *this;}
+    template <typename Types> any_image& operator=(const any_image<Types>& v) { parent_t::operator=((const typename make_variant_over<Types>::type&)v); return *this;}
 
     void recreate(const point_t& dims, unsigned alignment=1)
     {

include/boost/gil/extension/dynamic_image/any_image_view.hpp

@@ -8,7 +8,7 @@
 #ifndef BOOST_GIL_EXTENSION_DYNAMIC_IMAGE_ANY_IMAGE_VIEW_HPP
 #define BOOST_GIL_EXTENSION_DYNAMIC_IMAGE_ANY_IMAGE_VIEW_HPP
 
-#include <boost/gil/extension/dynamic_image/variant.hpp>
+#include <boost/variant.hpp>
 
 #include <boost/gil/image.hpp>
 #include <boost/gil/image_view.hpp>
@@ -57,8 +57,8 @@ namespace detail {
 /// To perform an algorithm on any_image_view, put the algorithm in a function object and invoke it by calling \p apply_operation(runtime_view, algorithm_fn);
 ////////////////////////////////////////////////////////////////////////////////////////
 template <typename ImageViewTypes>
-class any_image_view : public variant<ImageViewTypes> {
-    using parent_t = variant<ImageViewTypes>;
+class any_image_view : public make_variant_over<ImageViewTypes>::type {
+    using parent_t = typename make_variant_over<ImageViewTypes>::type;
 public:
     using const_t = any_image_view<typename detail::views_get_const_t<ImageViewTypes>::type>;
     using x_coord_t = std::ptrdiff_t;
@@ -68,11 +68,11 @@ class any_image_view : public variant<ImageViewTypes> {
     any_image_view()                                                          : parent_t() {}
     template <typename T> explicit any_image_view(const T& obj)               : parent_t(obj) {}
     any_image_view(const any_image_view& v)                                   : parent_t((const parent_t&)v)    {}
-    template <typename Types> any_image_view(const any_image_view<Types>& v)  : parent_t((const variant<Types>&)v)    {}
+    template <typename Types> any_image_view(const any_image_view<Types>& v)  : parent_t((const typename make_variant_over<Types>::type&)v)    {}
 
     template <typename T> any_image_view&     operator=(const T& obj)                   { parent_t::operator=(obj); return *this; }
     any_image_view&                           operator=(const any_image_view& v)        { parent_t::operator=((const parent_t&)v); return *this;}
-    template <typename Types> any_image_view& operator=(const any_image_view<Types>& v) { parent_t::operator=((const variant<Types>&)v); return *this;}
+    template <typename Types> any_image_view& operator=(const any_image_view<Types>& v) { parent_t::operator=((const typename make_variant_over<Types>::type&)v); return *this;}
 
     std::size_t num_channels()  const { return apply_operation(*this, detail::any_type_get_num_channels()); }
     point_t     dimensions()    const { return apply_operation(*this, detail::any_type_get_dimensions()); }

include/boost/gil/extension/dynamic_image/apply_operation.hpp

@@ -8,8 +8,7 @@
 #ifndef BOOST_GIL_EXTENSION_DYNAMIC_IMAGE_APPLY_OPERATION_HPP
 #define BOOST_GIL_EXTENSION_DYNAMIC_IMAGE_APPLY_OPERATION_HPP
 
-#include <boost/gil/extension/dynamic_image/apply_operation_base.hpp>
-#include <boost/gil/extension/dynamic_image/variant.hpp>
+#include <boost/variant/apply_visitor.hpp>
 
 #ifdef BOOST_GIL_DOXYGEN_ONLY
 #undef BOOST_GIL_REDUCE_CODE_BLOAT
@@ -30,19 +29,23 @@ namespace boost { namespace gil {
 template <typename Types, typename UnaryOp>
 BOOST_FORCEINLINE
 auto apply_operation(variant<Types>& arg, UnaryOp op)
+#if defined(BOOST_NO_CXX14_DECLTYPE_AUTO) || defined(BOOST_NO_CXX11_DECLTYPE_N3276)
     -> typename UnaryOp::result_type
+#endif
 {
-    return apply_operation_base<Types>(arg._bits, arg._index ,op);
+    return apply_visitor(op, arg);
 }
 
 /// \ingroup Variant
 /// \brief Invokes a generic constant operation (represented as a unary function object) on a variant
 template <typename Types, typename UnaryOp>
 BOOST_FORCEINLINE
 auto apply_operation(variant<Types> const& arg, UnaryOp op)
+#if defined(BOOST_NO_CXX14_DECLTYPE_AUTO) || defined(BOOST_NO_CXX11_DECLTYPE_N3276)
     -> typename UnaryOp::result_type
+#endif
 {
-    return apply_operation_basec<Types>(arg._bits, arg._index ,op);
+    return apply_visitor(op, arg);
 }
 
 /// \ingroup Variant
@@ -53,10 +56,12 @@ auto apply_operation(
     variant<Types1> const& arg1,
     variant<Types2> const& arg2,
     BinaryOp op)
+#if defined(BOOST_NO_CXX14_DECLTYPE_AUTO) || defined(BOOST_NO_CXX11_DECLTYPE_N3276)
     -> typename BinaryOp::result_type
+#endif
 {
-    return apply_operation_base<Types1, Types2>(
-        arg1._bits, arg1._index, arg2._bits, arg2._index, op);
+    return apply_visitor(
+        op, arg1, arg2);
 }
 
 }}  // namespace boost::gil

include/boost/gil/extension/dynamic_image/dynamic_image_all.hpp

@@ -11,7 +11,6 @@
 #include <boost/gil/extension/dynamic_image/algorithm.hpp>
 #include <boost/gil/extension/dynamic_image/any_image.hpp>
 #include <boost/gil/extension/dynamic_image/apply_operation.hpp>
-#include <boost/gil/extension/dynamic_image/variant.hpp>
 #include <boost/gil/extension/dynamic_image/image_view_factory.hpp>
 #include <boost/gil.hpp> // FIXME: Include what you use!