Made TypelessBuffer allocator-aware and split some of its functionality into MemoryView type.

source/mijin/container/memory_view.hpp

@@ -5,10 +5,10 @@
 #define MIJIN_CONTAINER_MEMORY_VIEW_HPP_INCLUDED 1
 
 #include <bit>
-#include <cstddef>
 #include <span>
+#include <string_view>
 #include "../debug/assert.hpp"
-#include "../util/traits.hpp"
+#include "../internal/common.hpp"
 
 namespace mijin
 {
@@ -25,60 +25,170 @@ namespace mijin
 // public types
 //
 
-template<typename TBytes>
-class MemoryViewBase
+template<typename T>
+concept MemoryViewable = requires(const T& object)
+{
+    { object.data() } -> std::convertible_to<const void*>;
+    { object.byteSize() } -> std::convertible_to<std::size_t>;
+};
+
+template<typename T>
+concept RWMemoryViewable = MemoryViewable<T> && requires(T& object)
+{
+    { object.data() } -> std::convertible_to<void*>;
+};
+
+template<typename TConcrete>
+class MixinMemoryView
+{
+public:
+    static constexpr bool WRITABLE = requires(TConcrete& object) { { object.data() } -> std::convertible_to<void*>; };
+
+    template<typename T>
+    [[nodiscard]]
+    auto makeSpan();
+
+    template<typename T>
+    [[nodiscard]]
+    auto makeSpan() const;
+
+    template<typename TChar = char, typename TTraits = std::char_traits<TChar>>
+    [[nodiscard]]
+    std::basic_string_view<TChar, TTraits> makeStringView() const ;
+
+    template<typename T>
+    [[nodiscard]]
+    auto& dataAt(std::size_t offset) MIJIN_NOEXCEPT;
+
+    template<typename T>
+    [[nodiscard]]
+    auto& dataAt(std::size_t offset) const MIJIN_NOEXCEPT;
+
+    [[nodiscard]]
+    auto bytes() MIJIN_NOEXCEPT
+    {
+        using return_t = mijin::copy_const_t<std::remove_pointer_t<decltype(static_cast<TConcrete*>(this)->data())>, std::byte>;
+        return static_cast<return_t*>(static_cast<TConcrete*>(this)->data());
+    }
+
+    [[nodiscard]]
+    auto bytes() const MIJIN_NOEXCEPT
+    {
+        using return_t = mijin::copy_const_t<std::remove_pointer_t<decltype(static_cast<const TConcrete*>(this)->data())>, std::byte>;
+        return static_cast<return_t*>(static_cast<const TConcrete*>(this)->data());
+    }
+private:
+    std::size_t byteSizeImpl() const MIJIN_NOEXCEPT
+    {
+        return static_cast<const TConcrete*>(this)->byteSize();
+    }
+};
+
+class MemoryView : public MixinMemoryView<MemoryView>
 {
 public:
     using size_type = std::size_t;
 private:
-    std::span<TBytes> bytes_;
+    void* data_ = nullptr;
+    std::size_t byteSize_ = 0;
 public:
-    MemoryViewBase() noexcept = default;
-    MemoryViewBase(const MemoryViewBase&) noexcept = default;
-    MemoryViewBase(copy_const_t<TBytes, void>* data, std::size_t size) noexcept : bytes_(static_cast<TBytes*>(data), size) {}
+    MemoryView() noexcept = default;
+    MemoryView(const MemoryView&) = default;
+    MemoryView(void* data, std::size_t byteSize) MIJIN_NOEXCEPT : data_(data), byteSize_(byteSize) {}
+    template<typename T> requires(!std::is_const_v<T>)
+    MemoryView(std::span<T> span) MIJIN_NOEXCEPT : data_(span.data()), byteSize_(span.size_bytes()) {}
+    template<RWMemoryViewable T>
+    MemoryView(T& memoryViewable) MIJIN_NOEXCEPT : data_(memoryViewable.data()), byteSize_(memoryViewable.byteSize()) {}
 
-    MemoryViewBase& operator=(const MemoryViewBase&) noexcept = default;
-    
-    [[nodiscard]] void* data() noexcept { return bytes_.data(); }
-    [[nodiscard]] const void* data() const noexcept { return bytes_.data(); }
-    [[nodiscard]] size_type byteSize() const noexcept { return bytes_.size(); }
-    [[nodiscard]] bool empty() const noexcept { return bytes_.empty(); }
+    MemoryView& operator=(const MemoryView&) = default;
 
-    template<typename T>
-    [[nodiscard]] std::span<T> makeSpan();
+    [[nodiscard]]
+    void* data() const MIJIN_NOEXCEPT { return data_; }
 
-    template<typename T>
-    [[nodiscard]] std::span<const T> makeSpan() const;
+    [[nodiscard]]
+    size_type byteSize() const MIJIN_NOEXCEPT { return byteSize_; }
+};
+
+class ConstMemoryView : public MixinMemoryView<ConstMemoryView>
+{
+public:
+    using size_type = std::size_t;
+private:
+    const void* data_;
+    std::size_t byteSize_;
+public:
+    ConstMemoryView() noexcept = default;
+    ConstMemoryView(const ConstMemoryView&) = default;
+    ConstMemoryView(void* data, std::size_t byteSize) MIJIN_NOEXCEPT : data_(data), byteSize_(byteSize) {}
+    template<typename T>
+    ConstMemoryView(std::span<T> span) MIJIN_NOEXCEPT : data_(span.data()), byteSize_(span.size_bytes()) {}
+    template<MemoryViewable T>
+    ConstMemoryView(const T& memoryViewable) MIJIN_NOEXCEPT : data_(memoryViewable.data()), byteSize_(memoryViewable.byteSize()) {}
+
+    [[nodiscard]]
+    const void* data() const MIJIN_NOEXCEPT { return data_; }
+
+    [[nodiscard]]
+    size_type byteSize() const MIJIN_NOEXCEPT { return byteSize_; }
 };
-using MemoryView = MemoryViewBase<std::byte>;
-using ConstMemoryView = MemoryViewBase<const std::byte>;
 
 //
 // public functions
 //
 
-template<typename TBytes>
+template<typename TConcrete>
 template<typename T>
-std::span<T> MemoryViewBase<TBytes>::makeSpan()
+auto MixinMemoryView<TConcrete>::makeSpan()
 {
-    static_assert(!std::is_const_v<TBytes>, "Cannot create writable spans from const memory views.");
-    MIJIN_ASSERT(bytes_.size() % sizeof(T) == 0, "MemoryView cannot be divided into elements of this type.");
-    return {
-        std::bit_cast<T*>(bytes_.data()),
-        std::bit_cast<T*>(bytes_.data() + bytes_.size())
+    MIJIN_ASSERT(byteSizeImpl() % sizeof(T) == 0, "Buffer cannot be divided into elements of this type.");
+    using return_t = mijin::copy_const_t<decltype(*bytes()), T>;
+    return std::span<return_t>{
+        std::bit_cast<return_t*>(bytes()),
+        std::bit_cast<return_t*>(bytes() + byteSizeImpl())
     };
 }
 
-template<typename TBytes>
+template<typename TConcrete>
 template<typename T>
-std::span<const T> MemoryViewBase<TBytes>::makeSpan() const
+auto MixinMemoryView<TConcrete>::makeSpan() const
 {
-    MIJIN_ASSERT(bytes_.size() % sizeof(T) == 0, "MemoryView cannot be divided into elements of this type.");
-    return {
-        std::bit_cast<const T*>(bytes_.data()),
-        std::bit_cast<const T*>(bytes_.data() + bytes_.size())
+    MIJIN_ASSERT(byteSizeImpl() % sizeof(T) == 0, "Buffer cannot be divided into elements of this type.");
+    using return_t = mijin::copy_const_t<decltype(*bytes()), T>;
+    return std::span<return_t>{
+        std::bit_cast<return_t*>(bytes()),
+        std::bit_cast<return_t*>(bytes() + byteSizeImpl())
     };
 }
+
+template<typename TConcrete>
+template<typename TChar, typename TTraits>
+std::basic_string_view<TChar, TTraits> MixinMemoryView<TConcrete>::makeStringView() const
+{
+    MIJIN_ASSERT(byteSizeImpl() % sizeof(TChar) == 0, "Buffer cannot be divided into elements of this char type.");
+    return {std::bit_cast<const TChar*>(bytes()), byteSizeImpl() / sizeof(TChar)};
+}
+
+template<typename TConcrete>
+template<typename T>
+auto& MixinMemoryView<TConcrete>::dataAt(std::size_t offset) MIJIN_NOEXCEPT
+{
+    MIJIN_ASSERT(offset % alignof(T) == 0, "Offset must be correctly aligned.");
+    MIJIN_ASSERT(offset + sizeof(T) < byteSizeImpl(), "Buffer access out-of-range.");
+
+    using return_t = mijin::copy_const_t<decltype(*bytes()), T>;
+    return *std::bit_cast<return_t*>(bytes().data() + offset);
+}
+
+template<typename TConcrete>
+template<typename T>
+auto& MixinMemoryView<TConcrete>::dataAt(std::size_t offset) const MIJIN_NOEXCEPT
+{
+    MIJIN_ASSERT(offset % alignof(T) == 0, "Offset must be correctly aligned.");
+    MIJIN_ASSERT(offset + sizeof(T) < byteSizeImpl(), "Buffer access out-of-range.");
+
+    using return_t = mijin::copy_const_t<decltype(*bytes()), T>;
+    return *std::bit_cast<return_t*>(bytes().data() + offset);
+}
 } // namespace mijin
 
 #endif // !defined(MIJIN_CONTAINER_MEMORY_VIEW_HPP_INCLUDED)