整理

include/boost/iterator/function_output_iterator.hpp

@@ -0,0 +1,89 @@
+// (C) Copyright Jeremy Siek 2001.
+// 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)
+
+// Revision History:
+
+// 27 Feb 2001   Jeremy Siek
+//      Initial checkin.
+
+#ifndef BOOST_ITERATOR_FUNCTION_OUTPUT_ITERATOR_HPP_INCLUDED_
+#define BOOST_ITERATOR_FUNCTION_OUTPUT_ITERATOR_HPP_INCLUDED_
+
+#include <cstddef>
+#include <iterator>
+#include <type_traits>
+
+namespace boost {
+namespace iterators {
+
+template< typename UnaryFunction >
+class function_output_iterator
+{
+private:
+    class output_proxy
+    {
+    public:
+        explicit output_proxy(UnaryFunction& f) noexcept :
+            m_f(f)
+        {}
+
+        template< typename T >
+        typename std::enable_if<
+            !std::is_same< typename std::remove_cv< typename std::remove_reference< T >::type >::type, output_proxy >::value,
+            output_proxy const&
+        >::type operator=(T&& value) const
+        {
+            m_f(static_cast< T&& >(value));
+            return *this;
+        }
+
+        output_proxy(output_proxy const& that) = default;
+        output_proxy& operator=(output_proxy const&) = delete;
+
+    private:
+        UnaryFunction& m_f;
+    };
+
+public:
+    using iterator_category = std::output_iterator_tag;
+    using value_type = void;
+    using difference_type = std::ptrdiff_t;
+    using pointer = void;
+    using reference = void;
+
+    template<
+        bool Requires = std::is_class< UnaryFunction >::value,
+        typename = typename std::enable_if< Requires >::type
+    >
+    function_output_iterator() :
+        m_f()
+    {}
+
+    explicit function_output_iterator(UnaryFunction const& f) :
+        m_f(f)
+    {}
+
+    output_proxy operator*() { return output_proxy(m_f); }
+    function_output_iterator& operator++() { return *this; }
+    function_output_iterator& operator++(int) { return *this; }
+
+private:
+    UnaryFunction m_f;
+};
+
+template< typename UnaryFunction >
+inline function_output_iterator< UnaryFunction > make_function_output_iterator(UnaryFunction const& f = UnaryFunction())
+{
+    return function_output_iterator< UnaryFunction >(f);
+}
+
+} // namespace iterators
+
+using iterators::function_output_iterator;
+using iterators::make_function_output_iterator;
+
+} // namespace boost
+
+#endif // BOOST_ITERATOR_FUNCTION_OUTPUT_ITERATOR_HPP_INCLUDED_