diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/Makefile.am | 1 | ||||
-rw-r--r-- | src/span.h | 40 |
2 files changed, 41 insertions, 0 deletions
diff --git a/src/Makefile.am b/src/Makefile.am index 72e5cdb95d..1cb4f46340 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -312,6 +312,7 @@ libbitcoin_consensus_a_SOURCES = \ script/script_error.cpp \ script/script_error.h \ serialize.h \ + span.h \ tinyformat.h \ uint256.cpp \ uint256.h \ diff --git a/src/span.h b/src/span.h new file mode 100644 index 0000000000..707fc21918 --- /dev/null +++ b/src/span.h @@ -0,0 +1,40 @@ +// Copyright (c) 2018 The Bitcoin Core developers +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#ifndef BITCOIN_SPAN_H +#define BITCOIN_SPAN_H + +#include <type_traits> +#include <cstddef> + +/** A Span is an object that can refer to a contiguous sequence of objects. + * + * It implements a subset of C++20's std::span. + */ +template<typename C> +class Span +{ + C* m_data; + std::ptrdiff_t m_size; + +public: + constexpr Span() noexcept : m_data(nullptr), m_size(0) {} + constexpr Span(C* data, std::ptrdiff_t size) noexcept : m_data(data), m_size(size) {} + + constexpr C* data() const noexcept { return m_data; } + constexpr std::ptrdiff_t size() const noexcept { return m_size; } +}; + +/** Create a span to a container exposing data() and size(). + * + * This correctly deals with constness: the returned Span's element type will be + * whatever data() returns a pointer to. If either the passed container is const, + * or its element type is const, the resulting span will have a const element type. + * + * std::span will have a constructor that implements this functionality directly. + */ +template<typename V> +constexpr Span<typename std::remove_pointer<decltype(std::declval<V>().data())>::type> MakeSpan(V& v) { return Span<typename std::remove_pointer<decltype(std::declval<V>().data())>::type>(v.data(), v.size()); } + +#endif |