850 lines
31 KiB
C++
850 lines
31 KiB
C++
///////////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2015 Microsoft Corporation. All rights reserved.
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//
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// This code is licensed under the MIT License (MIT).
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef GSL_SPAN_H
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#define GSL_SPAN_H
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#include "assert" // for Expects
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#include "byte" // for byte
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#include "span_ext" // for span specialization of gsl::at and other span-related extensions
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#include "util" // for narrow_cast
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#include <array> // for array
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#include <cstddef> // for ptrdiff_t, size_t, nullptr_t
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#include <iterator> // for reverse_iterator, distance, random_access_...
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#include <memory> // for pointer_traits
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#include <type_traits> // for enable_if_t, declval, is_convertible, inte...
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#if defined(__has_include) && __has_include(<version>)
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#include <version>
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#endif
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#if defined(_MSC_VER) && !defined(__clang__)
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#pragma warning(push)
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// turn off some warnings that are noisy about our Expects statements
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#pragma warning(disable : 4127) // conditional expression is constant
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#pragma warning( \
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disable : 4146) // unary minus operator applied to unsigned type, result still unsigned
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#pragma warning(disable : 4702) // unreachable code
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// Turn MSVC /analyze rules that generate too much noise. TODO: fix in the tool.
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#pragma warning(disable : 26495) // uninitialized member when constructor calls constructor
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#pragma warning(disable : 26446) // parser bug does not allow attributes on some templates
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#endif // _MSC_VER
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// See if we have enough C++17 power to use a static constexpr data member
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// without needing an out-of-line definition
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#if !(defined(__cplusplus) && (__cplusplus >= 201703L))
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#define GSL_USE_STATIC_CONSTEXPR_WORKAROUND
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#endif // !(defined(__cplusplus) && (__cplusplus >= 201703L))
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// GCC 7 does not like the signed unsigned mismatch (size_t ptrdiff_t)
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// While there is a conversion from signed to unsigned, it happens at
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// compiletime, so the compiler wouldn't have to warn indiscriminately, but
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// could check if the source value actually doesn't fit into the target type
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// and only warn in those cases.
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#if defined(__GNUC__) && __GNUC__ > 6
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wsign-conversion"
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#endif
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namespace gsl
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{
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// implementation details
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namespace details
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{
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template <class T>
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struct is_span_oracle : std::false_type
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{
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};
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template <class ElementType, std::size_t Extent>
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struct is_span_oracle<gsl::span<ElementType, Extent>> : std::true_type
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{
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};
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template <class T>
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struct is_span : public is_span_oracle<std::remove_cv_t<T>>
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{
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};
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template <class T>
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struct is_std_array_oracle : std::false_type
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{
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};
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template <class ElementType, std::size_t Extent>
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struct is_std_array_oracle<std::array<ElementType, Extent>> : std::true_type
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{
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};
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template <class T>
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struct is_std_array : is_std_array_oracle<std::remove_cv_t<T>>
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{
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};
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template <std::size_t From, std::size_t To>
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struct is_allowed_extent_conversion
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: std::integral_constant<bool, From == To || To == dynamic_extent>
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{
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};
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template <class From, class To>
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struct is_allowed_element_type_conversion
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: std::integral_constant<bool, std::is_convertible<From (*)[], To (*)[]>::value>
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{
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};
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template <class Type>
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class span_iterator
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{
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public:
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#if defined(__cpp_lib_ranges) || (defined(_MSVC_STL_VERSION) && defined(__cpp_lib_concepts))
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using iterator_concept = std::contiguous_iterator_tag;
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#endif // __cpp_lib_ranges
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using iterator_category = std::random_access_iterator_tag;
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using value_type = std::remove_cv_t<Type>;
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using difference_type = std::ptrdiff_t;
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using pointer = Type*;
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using reference = Type&;
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#ifdef _MSC_VER
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using _Unchecked_type = pointer;
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using _Prevent_inheriting_unwrap = span_iterator;
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#endif // _MSC_VER
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constexpr span_iterator() = default;
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constexpr span_iterator(pointer begin, pointer end, pointer current)
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: begin_(begin), end_(end), current_(current)
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{}
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constexpr operator span_iterator<const Type>() const noexcept
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{
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return {begin_, end_, current_};
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}
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constexpr reference operator*() const noexcept
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{
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Expects(begin_ && end_);
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Expects(begin_ <= current_ && current_ < end_);
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return *current_;
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}
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constexpr pointer operator->() const noexcept
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{
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Expects(begin_ && end_);
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Expects(begin_ <= current_ && current_ < end_);
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return current_;
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}
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constexpr span_iterator& operator++() noexcept
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{
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Expects(begin_ && current_ && end_);
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Expects(current_ < end_);
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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++current_;
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return *this;
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}
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constexpr span_iterator operator++(int) noexcept
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{
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span_iterator ret = *this;
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++*this;
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return ret;
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}
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constexpr span_iterator& operator--() noexcept
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{
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Expects(begin_ && end_);
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Expects(begin_ < current_);
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--current_;
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return *this;
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}
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constexpr span_iterator operator--(int) noexcept
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{
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span_iterator ret = *this;
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--*this;
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return ret;
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}
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constexpr span_iterator& operator+=(const difference_type n) noexcept
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{
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if (n != 0) Expects(begin_ && current_ && end_);
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if (n > 0) Expects(end_ - current_ >= n);
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if (n < 0) Expects(current_ - begin_ >= -n);
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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current_ += n;
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return *this;
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}
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constexpr span_iterator operator+(const difference_type n) const noexcept
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{
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span_iterator ret = *this;
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ret += n;
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return ret;
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}
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friend constexpr span_iterator operator+(const difference_type n,
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const span_iterator& rhs) noexcept
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{
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return rhs + n;
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}
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constexpr span_iterator& operator-=(const difference_type n) noexcept
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{
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if (n != 0) Expects(begin_ && current_ && end_);
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if (n > 0) Expects(current_ - begin_ >= n);
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if (n < 0) Expects(end_ - current_ >= -n);
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GSL_SUPPRESS(bounds .1)
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current_ -= n;
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return *this;
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}
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constexpr span_iterator operator-(const difference_type n) const noexcept
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{
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span_iterator ret = *this;
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ret -= n;
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return ret;
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr difference_type operator-(const span_iterator<Type2>& rhs) const noexcept
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{
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Expects(begin_ == rhs.begin_ && end_ == rhs.end_);
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return current_ - rhs.current_;
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}
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constexpr reference operator[](const difference_type n) const noexcept
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{
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return *(*this + n);
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr bool operator==(const span_iterator<Type2>& rhs) const noexcept
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{
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Expects(begin_ == rhs.begin_ && end_ == rhs.end_);
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return current_ == rhs.current_;
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr bool operator!=(const span_iterator<Type2>& rhs) const noexcept
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{
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return !(*this == rhs);
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr bool operator<(const span_iterator<Type2>& rhs) const noexcept
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{
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Expects(begin_ == rhs.begin_ && end_ == rhs.end_);
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return current_ < rhs.current_;
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr bool operator>(const span_iterator<Type2>& rhs) const noexcept
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{
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return rhs < *this;
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr bool operator<=(const span_iterator<Type2>& rhs) const noexcept
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{
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return !(rhs < *this);
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}
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template <
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class Type2,
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std::enable_if_t<std::is_same<std::remove_cv_t<Type2>, value_type>::value, int> = 0>
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constexpr bool operator>=(const span_iterator<Type2>& rhs) const noexcept
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{
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return !(*this < rhs);
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}
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#ifdef _MSC_VER
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// MSVC++ iterator debugging support; allows STL algorithms in 15.8+
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// to unwrap span_iterator to a pointer type after a range check in STL
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// algorithm calls
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friend constexpr void _Verify_range(span_iterator lhs, span_iterator rhs) noexcept
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{ // test that [lhs, rhs) forms a valid range inside an STL algorithm
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Expects(lhs.begin_ == rhs.begin_ // range spans have to match
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&& lhs.end_ == rhs.end_ &&
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lhs.current_ <= rhs.current_); // range must not be transposed
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}
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constexpr void _Verify_offset(const difference_type n) const noexcept
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{ // test that *this + n is within the range of this call
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if (n != 0) Expects(begin_ && current_ && end_);
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if (n > 0) Expects(end_ - current_ >= n);
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if (n < 0) Expects(current_ - begin_ >= -n);
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}
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// clang-format off
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GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
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// clang-format on
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constexpr pointer _Unwrapped() const noexcept
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{ // after seeking *this to a high water mark, or using one of the
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// _Verify_xxx functions above, unwrap this span_iterator to a raw
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// pointer
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return current_;
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}
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// Tell the STL that span_iterator should not be unwrapped if it can't
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// validate in advance, even in release / optimized builds:
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#if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
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static constexpr const bool _Unwrap_when_unverified = false;
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#else
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static constexpr bool _Unwrap_when_unverified = false;
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#endif
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// clang-format off
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GSL_SUPPRESS(con.3) // NO-FORMAT: attribute // TODO: false positive
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// clang-format on
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constexpr void _Seek_to(const pointer p) noexcept
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{ // adjust the position of *this to previously verified location p
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// after _Unwrapped
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current_ = p;
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}
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#endif
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pointer begin_ = nullptr;
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pointer end_ = nullptr;
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pointer current_ = nullptr;
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template <typename Ptr>
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friend struct std::pointer_traits;
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};
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}} // namespace gsl::details
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namespace std
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{
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template <class Type>
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struct pointer_traits<::gsl::details::span_iterator<Type>>
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{
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using pointer = ::gsl::details::span_iterator<Type>;
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using element_type = Type;
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using difference_type = ptrdiff_t;
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static constexpr element_type* to_address(const pointer i) noexcept { return i.current_; }
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};
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} // namespace std
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namespace gsl { namespace details {
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template <std::size_t Ext>
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class extent_type
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{
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public:
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using size_type = std::size_t;
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constexpr extent_type() noexcept = default;
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constexpr explicit extent_type(extent_type<dynamic_extent>);
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constexpr explicit extent_type(size_type size) { Expects(size == Ext); }
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constexpr size_type size() const noexcept { return Ext; }
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private:
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#if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
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static constexpr const size_type size_ = Ext; // static size equal to Ext
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#else
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static constexpr size_type size_ = Ext; // static size equal to Ext
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#endif
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};
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template <>
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class extent_type<dynamic_extent>
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{
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public:
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using size_type = std::size_t;
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template <size_type Other>
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constexpr explicit extent_type(extent_type<Other> ext) : size_(ext.size())
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{}
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constexpr explicit extent_type(size_type size) : size_(size)
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{
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Expects(size != dynamic_extent);
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}
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constexpr size_type size() const noexcept { return size_; }
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private:
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size_type size_;
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};
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template <std::size_t Ext>
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constexpr extent_type<Ext>::extent_type(extent_type<dynamic_extent> ext)
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{
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Expects(ext.size() == Ext);
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}
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template <class ElementType, std::size_t Extent, std::size_t Offset, std::size_t Count>
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struct calculate_subspan_type
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{
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using type = span<ElementType, Count != dynamic_extent
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? Count
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: (Extent != dynamic_extent ? Extent - Offset : Extent)>;
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};
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} // namespace details
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// [span], class template span
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template <class ElementType, std::size_t Extent>
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class span
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{
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public:
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// constants and types
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using element_type = ElementType;
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using value_type = std::remove_cv_t<ElementType>;
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using size_type = std::size_t;
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using pointer = element_type*;
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using const_pointer = const element_type*;
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using reference = element_type&;
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using const_reference = const element_type&;
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using difference_type = std::ptrdiff_t;
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using iterator = details::span_iterator<ElementType>;
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using reverse_iterator = std::reverse_iterator<iterator>;
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#if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
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static constexpr const size_type extent{Extent};
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#else
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static constexpr size_type extent{Extent};
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#endif
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// [span.cons], span constructors, copy, assignment, and destructor
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template <bool Dependent = false,
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// "Dependent" is needed to make "std::enable_if_t<Dependent || Extent == 0 || Extent
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// == dynamic_extent>" SFINAE, since "std::enable_if_t<Extent == 0 || Extent ==
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// dynamic_extent>" is ill-formed when Extent is greater than 0.
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class = std::enable_if_t<(Dependent ||
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details::is_allowed_extent_conversion<0, Extent>::value)>>
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constexpr span() noexcept : storage_(nullptr, details::extent_type<0>())
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{}
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template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent != dynamic_extent, int> = 0>
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constexpr explicit span(pointer ptr, size_type count) noexcept : storage_(ptr, count)
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{
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Expects(count == Extent);
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}
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template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent == dynamic_extent, int> = 0>
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constexpr span(pointer ptr, size_type count) noexcept : storage_(ptr, count)
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{}
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template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent != dynamic_extent, int> = 0>
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constexpr explicit span(pointer firstElem, pointer lastElem) noexcept
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: storage_(firstElem, narrow_cast<std::size_t>(lastElem - firstElem))
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{
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Expects(lastElem - firstElem == static_cast<difference_type>(Extent));
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}
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template <std::size_t MyExtent = Extent, std::enable_if_t<MyExtent == dynamic_extent, int> = 0>
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constexpr span(pointer firstElem, pointer lastElem) noexcept
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: storage_(firstElem, narrow_cast<std::size_t>(lastElem - firstElem))
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{}
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template <std::size_t N,
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std::enable_if_t<details::is_allowed_extent_conversion<N, Extent>::value, int> = 0>
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constexpr span(element_type (&arr)[N]) noexcept
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: storage_(KnownNotNull{arr}, details::extent_type<N>())
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{}
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template <
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class T, std::size_t N,
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std::enable_if_t<(details::is_allowed_extent_conversion<N, Extent>::value &&
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details::is_allowed_element_type_conversion<T, element_type>::value),
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int> = 0>
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constexpr span(std::array<T, N>& arr) noexcept
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: storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
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{}
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template <class T, std::size_t N,
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std::enable_if_t<
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(details::is_allowed_extent_conversion<N, Extent>::value &&
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details::is_allowed_element_type_conversion<const T, element_type>::value),
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int> = 0>
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constexpr span(const std::array<T, N>& arr) noexcept
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: storage_(KnownNotNull{arr.data()}, details::extent_type<N>())
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{}
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// NB: the SFINAE on these constructors uses .data() as an incomplete/imperfect proxy for the
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// requirement on Container to be a contiguous sequence container.
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template <std::size_t MyExtent = Extent, class Container,
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std::enable_if_t<
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MyExtent != dynamic_extent && !details::is_span<Container>::value &&
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!details::is_std_array<Container>::value &&
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std::is_pointer<decltype(std::declval<Container&>().data())>::value &&
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std::is_convertible<
|
|
std::remove_pointer_t<decltype(std::declval<Container&>().data())> (*)[],
|
|
element_type (*)[]>::value,
|
|
int> = 0>
|
|
constexpr explicit span(Container& cont) noexcept : span(cont.data(), cont.size())
|
|
{}
|
|
|
|
template <std::size_t MyExtent = Extent, class Container,
|
|
std::enable_if_t<
|
|
MyExtent == dynamic_extent && !details::is_span<Container>::value &&
|
|
!details::is_std_array<Container>::value &&
|
|
std::is_pointer<decltype(std::declval<Container&>().data())>::value &&
|
|
std::is_convertible<
|
|
std::remove_pointer_t<decltype(std::declval<Container&>().data())> (*)[],
|
|
element_type (*)[]>::value,
|
|
int> = 0>
|
|
constexpr span(Container& cont) noexcept : span(cont.data(), cont.size())
|
|
{}
|
|
|
|
template <
|
|
std::size_t MyExtent = Extent, class Container,
|
|
std::enable_if_t<
|
|
MyExtent != dynamic_extent && std::is_const<element_type>::value &&
|
|
!details::is_span<Container>::value && !details::is_std_array<Container>::value &&
|
|
std::is_pointer<decltype(std::declval<const Container&>().data())>::value &&
|
|
std::is_convertible<
|
|
std::remove_pointer_t<decltype(std::declval<const Container&>().data())> (*)[],
|
|
element_type (*)[]>::value,
|
|
int> = 0>
|
|
constexpr explicit span(const Container& cont) noexcept : span(cont.data(), cont.size())
|
|
{}
|
|
|
|
template <
|
|
std::size_t MyExtent = Extent, class Container,
|
|
std::enable_if_t<
|
|
MyExtent == dynamic_extent && std::is_const<element_type>::value &&
|
|
!details::is_span<Container>::value && !details::is_std_array<Container>::value &&
|
|
std::is_pointer<decltype(std::declval<const Container&>().data())>::value &&
|
|
std::is_convertible<
|
|
std::remove_pointer_t<decltype(std::declval<const Container&>().data())> (*)[],
|
|
element_type (*)[]>::value,
|
|
int> = 0>
|
|
constexpr span(const Container& cont) noexcept : span(cont.data(), cont.size())
|
|
{}
|
|
|
|
constexpr span(const span& other) noexcept = default;
|
|
|
|
template <class OtherElementType, std::size_t OtherExtent, std::size_t MyExtent = Extent,
|
|
std::enable_if_t<(MyExtent == dynamic_extent || MyExtent == OtherExtent) &&
|
|
details::is_allowed_element_type_conversion<OtherElementType,
|
|
element_type>::value,
|
|
int> = 0>
|
|
constexpr span(const span<OtherElementType, OtherExtent>& other) noexcept
|
|
: storage_(other.data(), details::extent_type<OtherExtent>(other.size()))
|
|
{}
|
|
|
|
template <class OtherElementType, std::size_t OtherExtent, std::size_t MyExtent = Extent,
|
|
std::enable_if_t<MyExtent != dynamic_extent && OtherExtent == dynamic_extent &&
|
|
details::is_allowed_element_type_conversion<OtherElementType,
|
|
element_type>::value,
|
|
int> = 0>
|
|
constexpr explicit span(const span<OtherElementType, OtherExtent>& other) noexcept
|
|
: storage_(other.data(), details::extent_type<OtherExtent>(other.size()))
|
|
{}
|
|
|
|
~span() noexcept = default;
|
|
constexpr span& operator=(const span& other) noexcept = default;
|
|
|
|
// [span.sub], span subviews
|
|
template <std::size_t Count>
|
|
constexpr span<element_type, Count> first() const noexcept
|
|
{
|
|
Expects(Count <= size());
|
|
return span<element_type, Count>{data(), Count};
|
|
}
|
|
|
|
template <std::size_t Count>
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
constexpr span<element_type, Count> last() const noexcept
|
|
{
|
|
Expects(Count <= size());
|
|
return span<element_type, Count>{data() + (size() - Count), Count};
|
|
}
|
|
|
|
template <std::size_t Offset, std::size_t Count = dynamic_extent>
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
constexpr auto subspan() const noexcept ->
|
|
typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type
|
|
{
|
|
Expects((size() >= Offset) && (Count == dynamic_extent || (Count <= size() - Offset)));
|
|
using type =
|
|
typename details::calculate_subspan_type<ElementType, Extent, Offset, Count>::type;
|
|
return type{data() + Offset, Count == dynamic_extent ? size() - Offset : Count};
|
|
}
|
|
|
|
constexpr span<element_type, dynamic_extent> first(size_type count) const noexcept
|
|
{
|
|
Expects(count <= size());
|
|
return {data(), count};
|
|
}
|
|
|
|
constexpr span<element_type, dynamic_extent> last(size_type count) const noexcept
|
|
{
|
|
Expects(count <= size());
|
|
return make_subspan(size() - count, dynamic_extent, subspan_selector<Extent>{});
|
|
}
|
|
|
|
constexpr span<element_type, dynamic_extent>
|
|
subspan(size_type offset, size_type count = dynamic_extent) const noexcept
|
|
{
|
|
return make_subspan(offset, count, subspan_selector<Extent>{});
|
|
}
|
|
|
|
// [span.obs], span observers
|
|
constexpr size_type size() const noexcept { return storage_.size(); }
|
|
|
|
constexpr size_type size_bytes() const noexcept { return size() * sizeof(element_type); }
|
|
|
|
constexpr bool empty() const noexcept { return size() == 0; }
|
|
|
|
// [span.elem], span element access
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
constexpr reference operator[](size_type idx) const noexcept
|
|
{
|
|
Expects(idx < size());
|
|
return data()[idx];
|
|
}
|
|
|
|
constexpr reference front() const noexcept
|
|
{
|
|
Expects(size() > 0);
|
|
return data()[0];
|
|
}
|
|
|
|
constexpr reference back() const noexcept
|
|
{
|
|
Expects(size() > 0);
|
|
return data()[size() - 1];
|
|
}
|
|
|
|
constexpr pointer data() const noexcept { return storage_.data(); }
|
|
|
|
// [span.iter], span iterator support
|
|
constexpr iterator begin() const noexcept
|
|
{
|
|
const auto data = storage_.data();
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
return {data, data + size(), data};
|
|
}
|
|
|
|
constexpr iterator end() const noexcept
|
|
{
|
|
const auto data = storage_.data();
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
const auto endData = data + storage_.size();
|
|
return {data, endData, endData};
|
|
}
|
|
|
|
constexpr reverse_iterator rbegin() const noexcept { return reverse_iterator{end()}; }
|
|
constexpr reverse_iterator rend() const noexcept { return reverse_iterator{begin()}; }
|
|
|
|
#ifdef _MSC_VER
|
|
// Tell MSVC how to unwrap spans in range-based-for
|
|
constexpr pointer _Unchecked_begin() const noexcept { return data(); }
|
|
constexpr pointer _Unchecked_end() const noexcept
|
|
{
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
return data() + size();
|
|
}
|
|
#endif // _MSC_VER
|
|
|
|
private:
|
|
// Needed to remove unnecessary null check in subspans
|
|
struct KnownNotNull
|
|
{
|
|
pointer p;
|
|
};
|
|
|
|
// this implementation detail class lets us take advantage of the
|
|
// empty base class optimization to pay for only storage of a single
|
|
// pointer in the case of fixed-size spans
|
|
template <class ExtentType>
|
|
class storage_type : public ExtentType
|
|
{
|
|
public:
|
|
// KnownNotNull parameter is needed to remove unnecessary null check
|
|
// in subspans and constructors from arrays
|
|
template <class OtherExtentType>
|
|
constexpr storage_type(KnownNotNull data, OtherExtentType ext)
|
|
: ExtentType(ext), data_(data.p)
|
|
{}
|
|
|
|
template <class OtherExtentType>
|
|
constexpr storage_type(pointer data, OtherExtentType ext) : ExtentType(ext), data_(data)
|
|
{
|
|
Expects(data || ExtentType::size() == 0);
|
|
}
|
|
|
|
constexpr pointer data() const noexcept { return data_; }
|
|
|
|
private:
|
|
pointer data_;
|
|
};
|
|
|
|
storage_type<details::extent_type<Extent>> storage_;
|
|
|
|
// The rest is needed to remove unnecessary null check
|
|
// in subspans and constructors from arrays
|
|
constexpr span(KnownNotNull ptr, size_type count) noexcept : storage_(ptr, count) {}
|
|
|
|
template <std::size_t CallerExtent>
|
|
class subspan_selector
|
|
{
|
|
};
|
|
|
|
template <std::size_t CallerExtent>
|
|
constexpr span<element_type, dynamic_extent>
|
|
make_subspan(size_type offset, size_type count, subspan_selector<CallerExtent>) const noexcept
|
|
{
|
|
const span<element_type, dynamic_extent> tmp(*this);
|
|
return tmp.subspan(offset, count);
|
|
}
|
|
|
|
// clang-format off
|
|
GSL_SUPPRESS(bounds.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
constexpr span<element_type, dynamic_extent>
|
|
make_subspan(size_type offset, size_type count, subspan_selector<dynamic_extent>) const noexcept
|
|
{
|
|
Expects(size() >= offset);
|
|
|
|
if (count == dynamic_extent) { return {KnownNotNull{data() + offset}, size() - offset}; }
|
|
|
|
Expects(size() - offset >= count);
|
|
return {KnownNotNull{data() + offset}, count};
|
|
}
|
|
};
|
|
|
|
#if (defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L))
|
|
|
|
// Deduction Guides
|
|
template <class Type, std::size_t Extent>
|
|
span(Type (&)[Extent]) -> span<Type, Extent>;
|
|
|
|
template <class Type, std::size_t Size>
|
|
span(std::array<Type, Size>&) -> span<Type, Size>;
|
|
|
|
template <class Type, std::size_t Size>
|
|
span(const std::array<Type, Size>&) -> span<const Type, Size>;
|
|
|
|
template <class Container,
|
|
class Element = std::remove_pointer_t<decltype(std::declval<Container&>().data())>>
|
|
span(Container&) -> span<Element>;
|
|
|
|
template <class Container,
|
|
class Element = std::remove_pointer_t<decltype(std::declval<const Container&>().data())>>
|
|
span(const Container&) -> span<Element>;
|
|
|
|
#endif // ( defined(__cpp_deduction_guides) && (__cpp_deduction_guides >= 201611L) )
|
|
|
|
#if defined(GSL_USE_STATIC_CONSTEXPR_WORKAROUND)
|
|
#if defined(__clang__) && defined(_MSC_VER) && defined(__cplusplus) && (__cplusplus < 201703L)
|
|
#pragma clang diagnostic push
|
|
#pragma clang diagnostic ignored "-Wdeprecated" // Bug in clang-cl.exe which raises a C++17 -Wdeprecated warning about this static constexpr workaround in C++14 mode.
|
|
#endif // defined(__clang__) && defined(_MSC_VER) && defined(__cplusplus) && (__cplusplus < 201703L)
|
|
template <class ElementType, std::size_t Extent>
|
|
constexpr const typename span<ElementType, Extent>::size_type span<ElementType, Extent>::extent;
|
|
#if defined(__clang__) && defined(_MSC_VER) && defined(__cplusplus) && (__cplusplus < 201703L)
|
|
#pragma clang diagnostic pop
|
|
#endif // defined(__clang__) && defined(_MSC_VER) && defined(__cplusplus) && (__cplusplus < 201703L)
|
|
#endif
|
|
|
|
namespace details
|
|
{
|
|
// if we only supported compilers with good constexpr support then
|
|
// this pair of classes could collapse down to a constexpr function
|
|
|
|
// we should use a narrow_cast<> to go to std::size_t, but older compilers may not see it as
|
|
// constexpr
|
|
// and so will fail compilation of the template
|
|
template <class ElementType, std::size_t Extent>
|
|
struct calculate_byte_size : std::integral_constant<std::size_t, sizeof(ElementType) * Extent>
|
|
{
|
|
static_assert(Extent < dynamic_extent / sizeof(ElementType), "Size is too big.");
|
|
};
|
|
|
|
template <class ElementType>
|
|
struct calculate_byte_size<ElementType, dynamic_extent>
|
|
: std::integral_constant<std::size_t, dynamic_extent>
|
|
{
|
|
};
|
|
} // namespace details
|
|
|
|
// [span.objectrep], views of object representation
|
|
template <class ElementType, std::size_t Extent>
|
|
span<const byte, details::calculate_byte_size<ElementType, Extent>::value>
|
|
as_bytes(span<ElementType, Extent> s) noexcept
|
|
{
|
|
using type = span<const byte, details::calculate_byte_size<ElementType, Extent>::value>;
|
|
|
|
// clang-format off
|
|
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
return type{reinterpret_cast<const byte*>(s.data()), s.size_bytes()};
|
|
}
|
|
|
|
template <class ElementType, std::size_t Extent,
|
|
std::enable_if_t<!std::is_const<ElementType>::value, int> = 0>
|
|
span<byte, details::calculate_byte_size<ElementType, Extent>::value>
|
|
as_writable_bytes(span<ElementType, Extent> s) noexcept
|
|
{
|
|
using type = span<byte, details::calculate_byte_size<ElementType, Extent>::value>;
|
|
|
|
// clang-format off
|
|
GSL_SUPPRESS(type.1) // NO-FORMAT: attribute
|
|
// clang-format on
|
|
return type{reinterpret_cast<byte*>(s.data()), s.size_bytes()};
|
|
}
|
|
|
|
} // namespace gsl
|
|
|
|
#if defined(_MSC_VER) && !defined(__clang__)
|
|
|
|
#pragma warning(pop)
|
|
#endif // _MSC_VER
|
|
|
|
#if defined(__GNUC__) && __GNUC__ > 6
|
|
#pragma GCC diagnostic pop
|
|
#endif // __GNUC__ > 6
|
|
|
|
#endif // GSL_SPAN_H
|