[vlc-devel] [PATCH] include: Add C++ memory management helpers

[Hugo Beauzée-Luyssen]

---
 include/vlc_cxx_helpers.hpp | 122 ++++++++++++++++++++++++++++++++++++
 src/Makefile.am             |   1 +
 2 files changed, 123 insertions(+)
 create mode 100644 include/vlc_cxx_helpers.hpp

diff --git a/include/vlc_cxx_helpers.hpp b/include/vlc_cxx_helpers.hpp
new file mode 100644
index 0000000000..130b5dcf0c
--- /dev/null
+++ b/include/vlc_cxx_helpers.hpp
@@ -0,0 +1,122 @@
+/*****************************************************************************
+ * vlc_cxx_helpers.hpp: C++ helpers
+ *****************************************************************************
+ * Copyright (C) 1998-2018 VLC authors and VideoLAN
+ *
+ * Authors: Hugo Beauzée-Luyssen <hugo at beauzee.fr>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifndef VLC_CXX_HELPERS_HPP
+#define VLC_CXX_HELPERS_HPP
+
+/******************************************************************************
+ * C++ memory management helpers
+ ******************************************************************************/
+
+#ifdef __cplusplus
+
+#include <memory>
+#include <utility>
+#include <type_traits>
+
+namespace vlc
+{
+
+namespace
+{
+// This helpers need static linkage to avoid their signature to change when
+// building as C++17 (noexcept becomes part of the function signature stating there)
+
+// Wraps a pointer with a custom releaser
+// ex: auto ptr = vlc_wrap_cptr( input_item, &input_item_Release );
+
+///
+/// Wraps a C pointer into a std::unique_ptr
+///
+/// This will convert a C pointer of type T to a std::unique_ptr<T, R> where
+/// T is the pointee type, and R is an arbitrary releaser type.
+///
+/// ptr will be automatically released by calling r( ptr ) when falling out of
+/// scope (whether by returning of by throwing an exception
+///
+/// @param ptr a C pointer
+/// @param r An instance of a Callable type, that will be invoked with ptr
+///          as its first and only parameter.
+template <typename T, typename Releaser>
+static inline auto wrap_cptr( T* ptr, Releaser&& r ) noexcept
+    -> std::unique_ptr<T, typename std::decay<decltype( r )>::type>
+{
+    return std::unique_ptr<T, typename std::decay<decltype( r )>::type>{
+                ptr, std::forward<Releaser>( r )
+    };
+}
+
+///
+/// Wraps a C pointer into a std::unique_ptr
+///
+/// This will convert a C pointer to an array of type T to a
+/// std::unique_ptr<T[], R> where T is the pointee type, and R is an arbitrary
+/// releaser type.
+///
+/// ptr will be automatically released by calling r( ptr ) when falling out of
+/// scope (whether by returning of by throwing an exception
+///
+/// This function is equivalent to wrap_cptr, except that the returned
+/// unique_ptr provides an operator[] for array access instead of operator* and
+/// operator->
+///
+/// @param ptr a C pointer
+/// @param r An instance of a Callable type, that will be invoked with ptr
+///          as its first and only parameter.
+template <typename T, typename Releaser>
+static inline auto wrap_carray( T* ptr, Releaser&& r ) noexcept
+    -> std::unique_ptr<T[], typename std::decay<decltype( r )>::type>
+{
+    return std::unique_ptr<T[], typename std::decay<decltype( r )>::type>{
+        ptr, std::forward<Releaser>( r )
+    };
+}
+
+///
+/// Wraps a C pointer into a std::unique_ptr
+///
+/// This is a convenience wrapper that will use free() as its releaser
+///
+template <typename T>
+static inline std::unique_ptr<T, void (*)(void*)> wrap_cptr( T* ptr ) noexcept
+{
+    return wrap_cptr( ptr, &free );
+}
+
+///
+/// Wraps a C pointer into a std::unique_ptr
+///
+/// This is a convenience wrapper that will use free() as its releaser
+///
+template <typename T>
+static inline std::unique_ptr<T[], void (*)(void*)> wrap_carray( T* ptr ) noexcept
+{
+    return wrap_carray( ptr, &free );
+}
+
+} // anonymous namespace
+
+} // namespace vlc
+
+#endif
+
+#endif // VLC_CXX_HELPERS_HPP
diff --git a/src/Makefile.am b/src/Makefile.am
index f9106a17c5..49ac01b26f 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -41,6 +41,7 @@ pluginsinclude_HEADERS = \
 	../include/vlc_config_cat.h \
 	../include/vlc_configuration.h \
 	../include/vlc_cpu.h \
+	../include/vlc_cxx_helpers.hpp \
 	../include/vlc_dialog.h \
 	../include/vlc_demux.h \
 	../include/vlc_epg.h \
-- 
2.18.0