diff options
Diffstat (limited to 'src/span.h')
| -rw-r--r-- | src/span.h | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/src/span.h b/src/span.h index 830164514b..746e41f2f4 100644 --- a/src/span.h +++ b/src/span.h @@ -30,7 +30,11 @@ /** A Span is an object that can refer to a contiguous sequence of objects. * - * It implements a subset of C++20's std::span. + * This file implements a subset of C++20's std::span. It can be considered + * temporary compatibility code until C++20 and is designed to be a + * self-contained abstraction without depending on other project files. For this + * reason, Clang lifetimebound is defined here instead of including + * <attributes.h>, which also defines it. * * Things to be aware of when writing code that deals with Spans: * @@ -60,7 +64,7 @@ * types that expose a data() and size() member function), functions that * accept a Span as input parameter can be called with any compatible * range-like object. For example, this works: -* + * * void Foo(Span<const int> arg); * * Foo(std::vector<int>{1, 2, 3}); // Works @@ -180,6 +184,7 @@ public: return m_data[m_size - 1]; } constexpr std::size_t size() const noexcept { return m_size; } + constexpr std::size_t size_bytes() const noexcept { return sizeof(C) * m_size; } constexpr bool empty() const noexcept { return size() == 0; } CONSTEXPR_IF_NOT_DEBUG C& operator[](std::size_t pos) const noexcept { @@ -236,11 +241,35 @@ T& SpanPopBack(Span<T>& span) return back; } +// From C++20 as_bytes and as_writeable_bytes +template <typename T> +Span<const std::byte> AsBytes(Span<T> s) noexcept +{ + return {reinterpret_cast<const std::byte*>(s.data()), s.size_bytes()}; +} +template <typename T> +Span<std::byte> AsWritableBytes(Span<T> s) noexcept +{ + return {reinterpret_cast<std::byte*>(s.data()), s.size_bytes()}; +} + +template <typename V> +Span<const std::byte> MakeByteSpan(V&& v) noexcept +{ + return AsBytes(MakeSpan(std::forward<V>(v))); +} +template <typename V> +Span<std::byte> MakeWritableByteSpan(V&& v) noexcept +{ + return AsWritableBytes(MakeSpan(std::forward<V>(v))); +} + // Helper functions to safely cast to unsigned char pointers. inline unsigned char* UCharCast(char* c) { return (unsigned char*)c; } inline unsigned char* UCharCast(unsigned char* c) { return c; } inline const unsigned char* UCharCast(const char* c) { return (unsigned char*)c; } inline const unsigned char* UCharCast(const unsigned char* c) { return c; } +inline const unsigned char* UCharCast(const std::byte* c) { return reinterpret_cast<const unsigned char*>(c); } // Helper function to safely convert a Span to a Span<[const] unsigned char>. template <typename T> constexpr auto UCharSpanCast(Span<T> s) -> Span<typename std::remove_pointer<decltype(UCharCast(s.data()))>::type> { return {UCharCast(s.data()), s.size()}; } @@ -248,4 +277,4 @@ template <typename T> constexpr auto UCharSpanCast(Span<T> s) -> Span<typename s /** Like MakeSpan, but for (const) unsigned char member types only. Only works for (un)signed char containers. */ template <typename V> constexpr auto MakeUCharSpan(V&& v) -> decltype(UCharSpanCast(MakeSpan(std::forward<V>(v)))) { return UCharSpanCast(MakeSpan(std::forward<V>(v))); } -#endif +#endif // BITCOIN_SPAN_H |