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Diffstat (limited to 'include/span.h')
-rw-r--r-- | include/span.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/include/span.h b/include/span.h new file mode 100644 index 00000000..4ea200f5 --- /dev/null +++ b/include/span.h @@ -0,0 +1,161 @@ +/***************************************************************************** + +Copyright (c) 2019, 2020 MariaDB Corporation. + +This program is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free Software +Foundation; version 2 of the License. + +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 General Public License for more details. + +You should have received a copy of the GNU General Public License along with +this program; if not, write to the Free Software Foundation, Inc., +51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA + +*****************************************************************************/ + +#pragma once + +#include <cstddef> +#include <iterator> + +namespace st_ +{ + +namespace detail +{ + +template <class T> struct remove_cv +{ + typedef T type; +}; +template <class T> struct remove_cv<const T> +{ + typedef T type; +}; +template <class T> struct remove_cv<volatile T> +{ + typedef T type; +}; +template <class T> struct remove_cv<const volatile T> +{ + typedef T type; +}; + +} // namespace detail + +template <class ElementType> class span +{ +public: + typedef ElementType element_type; + typedef typename detail::remove_cv<ElementType>::type value_type; + typedef size_t size_type; + typedef ptrdiff_t difference_type; + typedef element_type *pointer; + typedef const element_type *const_pointer; + typedef element_type &reference; + typedef const element_type &const_reference; + typedef pointer iterator; + typedef const_pointer const_iterator; + typedef std::reverse_iterator<iterator> reverse_iterator; + + span() : data_(NULL), size_(0) {} + + span(pointer ptr, size_type count) : data_(ptr), size_(count) {} + + span(pointer first, pointer last) : data_(first), size_(last - first) {} + + template <size_t N> span(element_type (&arr)[N]) : data_(arr), size_(N) {} + + template <class Container> + span(Container &cont) : data_(cont.data()), size_(cont.size()) + { + } + + template <class Container> + span(const Container &cont) : data_(cont.data()), size_(cont.size()) + { + } + + span(const span &other) : data_(other.data_), size_(other.size_) {} + + ~span() = default; + + span &operator=(const span &other) + { + data_= other.data(); + size_= other.size(); + return *this; + } + + template <size_t Count> span<element_type> first() const + { + assert(!empty()); + return span(data(), 1); + } + template <size_t Count> span<element_type> last() const + { + assert(!empty()); + return span(data() + size() - 1, 1); + } + + span<element_type> first(size_type count) const + { + assert(!empty()); + return span(data(), 1); + } + span<element_type> last(size_type count) const + { + assert(!empty()); + return span(data() + size() - 1, 1); + } + span<element_type> subspan(size_type offset, size_type count) const + { + assert(!empty()); + assert(size() >= offset + count); + return span(data() + offset, count); + } + + size_type size() const { return size_; } + size_type size_bytes() const { return size() * sizeof(ElementType); } + bool empty() const __attribute__((warn_unused_result)) + { + return size() == 0; + } + + reference operator[](size_type idx) const + { + assert(size() > idx); + return data()[idx]; + } + reference front() const + { + assert(!empty()); + return data()[0]; + } + reference back() const + { + assert(!empty()); + return data()[size() - 1]; + } + pointer data() const { return data_; } + + iterator begin() const { return data_; } + iterator end() const { return data_ + size_; } + reverse_iterator rbegin() const + { + return std::reverse_iterator<iterator>(end()); + } + reverse_iterator rend() const + { + return std::reverse_iterator<iterator>(begin()); + } + +private: + pointer data_; + size_type size_; +}; + +} // namespace st_ |