整理

include/boost/iterator/indirect_iterator.hpp

@@ -0,0 +1,121 @@
+// (C) Copyright David Abrahams 2002.
+// (C) Copyright Jeremy Siek    2002.
+// (C) Copyright Thomas Witt    2002.
+// 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)
+#ifndef BOOST_INDIRECT_ITERATOR_23022003THW_HPP
+#define BOOST_INDIRECT_ITERATOR_23022003THW_HPP
+
+#include <iterator>
+#include <type_traits>
+
+#include <boost/iterator/iterator_adaptor.hpp>
+#include <boost/iterator/enable_if_convertible.hpp>
+#include <boost/iterator/detail/eval_if_default.hpp>
+
+#include <boost/pointee.hpp>
+#include <boost/indirect_reference.hpp>
+
+#include <boost/core/use_default.hpp>
+
+namespace boost {
+namespace iterators {
+
+template< typename Iter, typename Value, typename Category, typename Reference, typename Difference >
+class indirect_iterator;
+
+namespace detail {
+
+template< typename Iter, typename Value, typename Category, typename Reference, typename Difference >
+struct indirect_base
+{
+    using dereferenceable = typename std::iterator_traits< Iter >::value_type;
+
+    using type = iterator_adaptor<
+        indirect_iterator< Iter, Value, Category, Reference, Difference >,
+        Iter,
+        detail::eval_if_default_t<
+            Value,
+            pointee< dereferenceable >
+        >,
+        Category,
+        detail::eval_if_default_t<
+            Reference,
+            detail::eval_if_default<
+                Value,
+                indirect_reference< dereferenceable >,
+                std::add_lvalue_reference< Value >
+            >
+        >,
+        Difference
+    >;
+};
+
+} // namespace detail
+
+
+template<
+    typename Iterator,
+    typename Value = use_default,
+    typename Category = use_default,
+    typename Reference = use_default,
+    typename Difference = use_default
+>
+class indirect_iterator :
+    public detail::indirect_base<
+        Iterator, Value, Category, Reference, Difference
+    >::type
+{
+    using super_t = typename detail::indirect_base<
+        Iterator, Value, Category, Reference, Difference
+    >::type;
+
+    friend class iterator_core_access;
+
+public:
+    indirect_iterator() = default;
+
+    indirect_iterator(Iterator iter) :
+        super_t(iter)
+    {}
+
+    template<
+        typename Iterator2,
+        typename Value2,
+        typename Category2,
+        typename Reference2,
+        typename Difference2,
+        typename = enable_if_convertible_t< Iterator2, Iterator >
+    >
+    indirect_iterator(indirect_iterator< Iterator2, Value2, Category2, Reference2, Difference2 > const& y) :
+        super_t(y.base())
+    {}
+
+private:
+    typename super_t::reference dereference() const
+    {
+        return **this->base();
+    }
+};
+
+template< typename Iter >
+inline indirect_iterator< Iter > make_indirect_iterator(Iter x)
+{
+    return indirect_iterator< Iter >(x);
+}
+
+template< typename Value, typename Iter >
+inline indirect_iterator< Iter, Value > make_indirect_iterator(Iter x)
+{
+    return indirect_iterator< Iter, Value >(x);
+}
+
+} // namespace iterators
+
+using iterators::indirect_iterator;
+using iterators::make_indirect_iterator;
+
+} // namespace boost
+
+#endif // BOOST_INDIRECT_ITERATOR_23022003THW_HPP