Split algorithm::mapped_span<T> into map_view<T> and mapped<T>, as per the TS wording.

1 files changed, 87 insertions, 0 deletions

diff --git a/include/llfio/v2.0/map_view.hpp b/include/llfio/v2.0/map_view.hpp
new file mode 100644
index 00000000..b4811891
--- /dev/null
+++ b/include/llfio/v2.0/map_view.hpp
@@ -0,0 +1,87 @@
+/* A typed view of a mapped section
+(C) 2017-2018 Niall Douglas <http://www.nedproductions.biz/> (12 commits)
+File Created: Aug 2017
+
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License in the accompanying file
+Licence.txt or at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+
+Distributed under the Boost Software License, Version 1.0.
+    (See accompanying file Licence.txt or copy at
+          http://www.boost.org/LICENSE_1_0.txt)
+*/
+
+#ifndef LLFIO_MAP_VIEW_HPP
+#define LLFIO_MAP_VIEW_HPP
+
+#include "mapped.hpp"
+
+//! \file map_view.hpp Provides typed view of mapped section.
+
+LLFIO_V2_NAMESPACE_BEGIN
+
+/*! \brief Provides a lightweight typed view of a `map_handle`, a `mapped_file_handle`
+or a `mapped<T>` suitable for feeding to STL algorithms or the Ranges TS.
+
+This is the correct type to use when passing non-owning views of mapped data
+around between functions. Where you wish the view to be (possibly) owning,
+you may find the non-lightweight `mapped<T>` of more use.
+*/
+template <class T> class map_view : public span<T>
+{
+public:
+  //! The extent type.
+  using extent_type = typename section_handle::extent_type;
+  //! The size type.
+  using size_type = typename section_handle::size_type;
+
+public:
+  //! Default constructor
+  constexpr map_view() {}  // NOLINT
+
+  /*! Implicitly construct a mapped view of the given mapped data.
+
+  \param map The mapped data to take a view upon.
+  \param length The number of items to map, use -1 to mean the length of the input view.
+  \param byteoffset The item offset into the mapped file handle.
+  */
+  map_view(mapped<T> &map, size_type length = (size_type) -1, size_type offset = 0)             // NOLINT
+  : span<T>(map.begin() + offset, (length == (size_type) -1) ? (map.size() - offset) : length)  // NOLINT
+  {
+  }
+  /*! Construct a mapped view of the given map handle.
+
+  \param mh The map handle to use.
+  \param length The number of items to map, use -1 to mean the length of the map handle divided by `sizeof(T)`.
+  \param byteoffset The byte offset into the map handle, this does not need to be a multiple of the page size.
+  */
+  explicit map_view(map_handle &mh, size_type length = (size_type) -1, extent_type byteoffset = 0)                                             // NOLINT
+  : span<T>(reinterpret_cast<T *>(mh.address() + byteoffset), (length == (size_type) -1) ? ((mh.length() - byteoffset) / sizeof(T)) : length)  // NOLINT
+  {
+  }
+  /*! Construct a mapped view of the given mapped file handle.
+
+  \param mfh The mapped file handle to take a view upon.
+  \param length The number of items to map, use -1 to mean the length of the section handle divided by `sizeof(T)`.
+  \param byteoffset The byte offset into the mapped file handle, this does not need to be a multiple of the page size.
+  */
+  explicit map_view(mapped_file_handle &mfh, size_type length = (size_type) -1, extent_type byteoffset = 0)                                                      // NOLINT
+  : span<T>(reinterpret_cast<T *>(mfh.address() + byteoffset), (length == (size_type) -1) ? ((mfh.maximum_extent().value() - byteoffset) / sizeof(T)) : length)  // NOLINT
+  {
+  }
+};
+
+LLFIO_V2_NAMESPACE_END
+
+#endif