整理

include/boost/iterator/generator_iterator.hpp

@@ -0,0 +1,96 @@
+// (C) Copyright Jens Maurer 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:
+
+// 15 Nov 2001   Jens Maurer
+//      created.
+
+//  See http://www.boost.org/libs/utility/iterator_adaptors.htm for documentation.
+
+#ifndef BOOST_ITERATOR_GENERATOR_ITERATOR_HPP_INCLUDED_
+#define BOOST_ITERATOR_GENERATOR_ITERATOR_HPP_INCLUDED_
+
+#include <memory>
+#include <type_traits>
+
+#include <boost/iterator/iterator_facade.hpp>
+#include <boost/iterator/iterator_categories.hpp>
+
+namespace boost {
+namespace iterators {
+
+template< typename Generator >
+class generator_iterator :
+    public iterator_facade<
+        generator_iterator< Generator >,
+        decltype(std::declval< Generator& >()()),
+        single_pass_traversal_tag,
+        decltype(std::declval< Generator& >()()) const&
+    >
+{
+    friend class iterator_core_access;
+
+private:
+    using super_t = iterator_facade<
+        generator_iterator< Generator >,
+        decltype(std::declval< Generator& >()()),
+        single_pass_traversal_tag,
+        decltype(std::declval< Generator& >()()) const&
+    >;
+
+public:
+    generator_iterator() :
+        m_g(nullptr),
+        m_value()
+    {}
+
+    generator_iterator(Generator* g) :
+        m_g(g),
+        m_value((*m_g)())
+    {}
+
+private:
+    void increment()
+    {
+        m_value = (*m_g)();
+    }
+
+    typename super_t::reference dereference() const
+    {
+        return m_value;
+    }
+
+    bool equal(generator_iterator const& y) const
+    {
+        return m_g == y.m_g && m_value == y.m_value;
+    }
+
+private:
+    Generator* m_g;
+    typename Generator::result_type m_value;
+};
+
+template< typename Generator >
+struct generator_iterator_generator
+{
+    using type = generator_iterator< Generator >;
+};
+
+template< typename Generator >
+inline generator_iterator< Generator > make_generator_iterator(Generator& gen)
+{
+    return generator_iterator< Generator >(std::addressof(gen));
+}
+
+} // namespace iterators
+
+using iterators::generator_iterator;
+using iterators::generator_iterator_generator;
+using iterators::make_generator_iterator;
+
+} // namespace boost
+
+#endif // BOOST_ITERATOR_GENERATOR_ITERATOR_HPP_INCLUDED_