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/*
* Copyright Michael Schellenberger Costa
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
*/
#ifndef ACO_UTIL_H
#define ACO_UTIL_H
#include <cassert>
#include <iterator>
namespace aco {
/*! \brief Definition of a span object
*
* \details A "span" is an "array view" type for holding a view of contiguous
* data. The "span" object does not own the data itself.
*/
template <typename T>
class span {
public:
using value_type = T;
using pointer = value_type*;
using const_pointer = const value_type*;
using reference = value_type&;
using const_reference = const value_type&;
using iterator = pointer;
using const_iterator = const_pointer;
using reverse_iterator = std::reverse_iterator<iterator>;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using size_type = uint16_t;
using difference_type = ptrdiff_t;
/*! \brief Compiler generated default constructor
*/
constexpr span() = default;
/*! \brief Constructor taking a pointer and the length of the span
* \param[in] data Pointer to the underlying data array
* \param[in] length The size of the span
*/
constexpr span(uint16_t offset, const size_type length)
: offset{ offset } , length{ length } {}
/*! \brief Returns an iterator to the begin of the span
* \return data
*/
constexpr iterator begin() noexcept {
return (pointer)((char*)this + offset);
}
/*! \brief Returns a const_iterator to the begin of the span
* \return data
*/
constexpr const_iterator begin() const noexcept {
return (const_pointer)((const char *)this + offset);
}
/*! \brief Returns an iterator to the end of the span
* \return data + length
*/
constexpr iterator end() noexcept {
return std::next(begin(), length);
}
/*! \brief Returns a const_iterator to the end of the span
* \return data + length
*/
constexpr const_iterator end() const noexcept {
return std::next(begin(), length);
}
/*! \brief Returns a const_iterator to the begin of the span
* \return data
*/
constexpr const_iterator cbegin() const noexcept {
return begin();
}
/*! \brief Returns a const_iterator to the end of the span
* \return data + length
*/
constexpr const_iterator cend() const noexcept {
return std::next(begin(), length);
}
/*! \brief Returns a reverse_iterator to the end of the span
* \return reverse_iterator(end())
*/
constexpr reverse_iterator rbegin() noexcept {
return reverse_iterator(end());
}
/*! \brief Returns a const_reverse_iterator to the end of the span
* \return reverse_iterator(end())
*/
constexpr const_reverse_iterator rbegin() const noexcept {
return const_reverse_iterator(end());
}
/*! \brief Returns a reverse_iterator to the begin of the span
* \return reverse_iterator(begin())
*/
constexpr reverse_iterator rend() noexcept {
return reverse_iterator(begin());
}
/*! \brief Returns a const_reverse_iterator to the begin of the span
* \return reverse_iterator(begin())
*/
constexpr const_reverse_iterator rend() const noexcept {
return const_reverse_iterator(begin());
}
/*! \brief Returns a const_reverse_iterator to the end of the span
* \return rbegin()
*/
constexpr const_reverse_iterator crbegin() const noexcept {
return const_reverse_iterator(cend());
}
/*! \brief Returns a const_reverse_iterator to the begin of the span
* \return rend()
*/
constexpr const_reverse_iterator crend() const noexcept {
return const_reverse_iterator(cbegin());
}
/*! \brief Unchecked access operator
* \param[in] index Index of the element we want to access
* \return *(std::next(data, index))
*/
constexpr reference operator[](const size_type index) noexcept {
assert(length > index);
return *(std::next(begin(), index));
}
/*! \brief Unchecked const access operator
* \param[in] index Index of the element we want to access
* \return *(std::next(data, index))
*/
constexpr const_reference operator[](const size_type index) const noexcept {
assert(length > index);
return *(std::next(begin(), index));
}
/*! \brief Returns a reference to the last element of the span
* \return *(std::next(data, length - 1))
*/
constexpr reference back() noexcept {
assert(length > 0);
return *(std::next(begin(), length - 1));
}
/*! \brief Returns a const_reference to the last element of the span
* \return *(std::next(data, length - 1))
*/
constexpr const_reference back() const noexcept {
assert(length > 0);
return *(std::next(begin(), length - 1));
}
/*! \brief Returns a reference to the first element of the span
* \return *begin()
*/
constexpr reference front() noexcept {
assert(length > 0);
return *begin();
}
/*! \brief Returns a const_reference to the first element of the span
* \return *cbegin()
*/
constexpr const_reference front() const noexcept {
assert(length > 0);
return *cbegin();
}
/*! \brief Returns true if the span is empty
* \return length == 0
*/
constexpr bool empty() const noexcept {
return length == 0;
}
/*! \brief Returns the size of the span
* \return length == 0
*/
constexpr size_type size() const noexcept {
return length;
}
/*! \brief Decreases the size of the span by 1
*/
constexpr void pop_back() noexcept {
assert(length > 0);
--length;
}
/*! \brief Clears the span
*/
constexpr void clear() noexcept {
offset = 0;
length = 0;
}
private:
uint16_t offset{ 0 }; //!> Byte offset from span to data
size_type length{ 0 }; //!> Size of the span
};
} // namespace aco
#endif // ACO_UTIL_H
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