WIP: Add C++ bindings

1 files changed, 141 insertions, 0 deletions

diff --git a/bindings/cpp/include/serd/detail/Wrapper.hpp b/bindings/cpp/include/serd/detail/Wrapper.hpp
new file mode 100644
index 00000000..10395ec4
--- /dev/null
+++ b/bindings/cpp/include/serd/detail/Wrapper.hpp
@@ -0,0 +1,141 @@
+/*
+  Copyright 2019-2020 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef SERD_DETAIL_WRAPPER_HPP
+#define SERD_DETAIL_WRAPPER_HPP
+
+#include <cstddef>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+namespace serd {
+namespace detail {
+
+template<typename T>
+class Optional;
+
+/// Free function for a C object
+template<typename T>
+using FreeFunc = void (*)(T*);
+
+template<class T>
+using Mutable = typename std::remove_const<T>::type;
+
+/**
+   Simple overhead-free deleter for a C object.
+
+   Can be used with const or mutable pointers, but only mutable pointers will
+   be freed.  This makes it simple to wrap APIs where constness conveys
+   ownership, but can not handle unowned mutable pointers.
+*/
+template<typename T, void Free(Mutable<T>*)>
+struct BasicDeleter {
+  template<typename = std::enable_if<!std::is_const<T>::value>>
+  void operator()(typename std::remove_const<T>::type* ptr)
+  {
+    Free(ptr);
+  }
+
+  template<typename = std::enable_if<std::is_const<T>::value>>
+  void operator()(const T*)
+  {}
+};
+
+/// Ownership for `DynamicDeleter`
+enum class Ownership { owned, view };
+
+/**
+   Deleter for a C object that can handle dynamic ownership.
+
+   Unlike `BasicDeleter`, this can be used to handle non-owned references to
+   mutable objects, at the cost of an extra word for tracking the ownership
+   (since constness in the type can't convey this information).
+*/
+template<typename T, void Free(Mutable<T>*)>
+struct DynamicDeleter : BasicDeleter<T, Free> {
+  // NOLINTNEXTLINE(google-explicit-constructor, hicpp-explicit-conversions)
+  DynamicDeleter(Ownership ownership)
+    : _ownership{ownership}
+  {}
+
+  void operator()(T* ptr)
+  {
+    if (_ownership == Ownership::owned) {
+      BasicDeleter<T, Free>::operator()(ptr);
+    }
+  }
+
+private:
+  Ownership _ownership;
+};
+
+/// Generic C++ wrapper for a C object
+template<typename T, class Deleter>
+class Wrapper
+{
+public:
+  using CType = T;
+  using UPtr  = std::unique_ptr<T, Deleter>;
+
+  explicit Wrapper(T* ptr)
+    : _ptr(ptr, Deleter{})
+  {}
+
+  Wrapper(T* ptr, Deleter deleter)
+    : _ptr(ptr, std::move(deleter))
+  {}
+
+  explicit Wrapper(UPtr ptr)
+    : _ptr(std::move(ptr))
+  {}
+
+  Wrapper(Wrapper&&) noexcept = default;
+  Wrapper& operator=(Wrapper&&) noexcept = default;
+
+  Wrapper(const Wrapper&) = delete;
+  Wrapper& operator=(const Wrapper&) = delete;
+
+  ~Wrapper() = default;
+
+  T*       cobj() { return _ptr.get(); }
+  const T* cobj() const { return _ptr.get(); }
+
+protected:
+  friend class detail::Optional<T>;
+
+  explicit Wrapper(std::nullptr_t)
+    : _ptr(nullptr)
+  {}
+
+  void reset() { _ptr.reset(); }
+
+  std::unique_ptr<T, Deleter> _ptr;
+};
+
+template<typename T, void Free(Mutable<T>*)>
+class BasicWrapper : public Wrapper<T, BasicDeleter<T, Free>>
+{
+public:
+  explicit BasicWrapper(T* ptr)
+    : Wrapper<T, BasicDeleter<T, Free>>{ptr}
+  {}
+};
+
+} // namespace detail
+} // namespace serd
+
+#endif // SERD_DETAIL_WRAPPER_HPP