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//===--- ArrayRef.h - Array Reference Wrapper -------------------*- C++ -*-===// | |
// | |
// The LLVM Compiler Infrastructure | |
// | |
// This file is distributed under the University of Illinois Open Source | |
// License. See LICENSE.TXT for details. | |
// | |
//===----------------------------------------------------------------------===// | |
// ATen: modified from llvm::ArrayRef. | |
// removed llvm-specific functionality | |
// removed some implicit const -> non-const conversions that rely on | |
// complicated std::enable_if meta-programming | |
// removed a bunch of slice variants for simplicity... | |
namespace c10 { | |
/// ArrayRef - Represent a constant reference to an array (0 or more elements | |
/// consecutively in memory), i.e. a start pointer and a length. It allows | |
/// various APIs to take consecutive elements easily and conveniently. | |
/// | |
/// This class does not own the underlying data, it is expected to be used in | |
/// situations where the data resides in some other buffer, whose lifetime | |
/// extends past that of the ArrayRef. For this reason, it is not in general | |
/// safe to store an ArrayRef. | |
/// | |
/// This is intended to be trivially copyable, so it should be passed by | |
/// value. | |
template <typename T> | |
class ArrayRef final { | |
public: | |
using iterator = const T*; | |
using const_iterator = const T*; | |
using size_type = size_t; | |
using value_type = T; | |
using reverse_iterator = std::reverse_iterator<iterator>; | |
private: | |
/// The start of the array, in an external buffer. | |
const T* Data; | |
/// The number of elements. | |
size_type Length; | |
void debugCheckNullptrInvariant() { | |
TORCH_INTERNAL_ASSERT_DEBUG_ONLY( | |
Data != nullptr || Length == 0, | |
"created ArrayRef with nullptr and non-zero length! c10::optional relies on this being illegal"); | |
} | |
public: | |
/// @name Constructors | |
/// @{ | |
/// Construct an empty ArrayRef. | |
/* implicit */ constexpr ArrayRef() : Data(nullptr), Length(0) {} | |
/// Construct an ArrayRef from a single element. | |
// TODO Make this explicit | |
constexpr ArrayRef(const T& OneElt) : Data(&OneElt), Length(1) {} | |
/// Construct an ArrayRef from a pointer and length. | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA ArrayRef(const T* data, size_t length) | |
: Data(data), Length(length) { | |
debugCheckNullptrInvariant(); | |
} | |
/// Construct an ArrayRef from a range. | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA ArrayRef(const T* begin, const T* end) | |
: Data(begin), Length(end - begin) { | |
debugCheckNullptrInvariant(); | |
} | |
/// Construct an ArrayRef from a SmallVector. This is templated in order to | |
/// avoid instantiating SmallVectorTemplateCommon<T> whenever we | |
/// copy-construct an ArrayRef. | |
template <typename U> | |
/* implicit */ ArrayRef(const SmallVectorTemplateCommon<T, U>& Vec) | |
: Data(Vec.data()), Length(Vec.size()) { | |
debugCheckNullptrInvariant(); | |
} | |
template < | |
typename Container, | |
typename = std::enable_if_t<std::is_same_v< | |
std::remove_const_t<decltype(std::declval<Container>().data())>, | |
T*>>> | |
/* implicit */ ArrayRef(const Container& container) | |
: Data(container.data()), Length(container.size()) { | |
debugCheckNullptrInvariant(); | |
} | |
/// Construct an ArrayRef from a std::vector. | |
// The enable_if stuff here makes sure that this isn't used for | |
// std::vector<bool>, because ArrayRef can't work on a std::vector<bool> | |
// bitfield. | |
template <typename A> | |
/* implicit */ ArrayRef(const std::vector<T, A>& Vec) | |
: Data(Vec.data()), Length(Vec.size()) { | |
static_assert( | |
!std::is_same<T, bool>::value, | |
"ArrayRef<bool> cannot be constructed from a std::vector<bool> bitfield."); | |
} | |
/// Construct an ArrayRef from a std::array | |
template <size_t N> | |
/* implicit */ constexpr ArrayRef(const std::array<T, N>& Arr) | |
: Data(Arr.data()), Length(N) {} | |
/// Construct an ArrayRef from a C array. | |
template <size_t N> | |
// NOLINTNEXTLINE(*c-arrays*) | |
/* implicit */ constexpr ArrayRef(const T (&Arr)[N]) : Data(Arr), Length(N) {} | |
/// Construct an ArrayRef from a std::initializer_list. | |
/* implicit */ constexpr ArrayRef(const std::initializer_list<T>& Vec) | |
: Data( | |
std::begin(Vec) == std::end(Vec) ? static_cast<T*>(nullptr) | |
: std::begin(Vec)), | |
Length(Vec.size()) {} | |
/// @} | |
/// @name Simple Operations | |
/// @{ | |
constexpr iterator begin() const { | |
return Data; | |
} | |
constexpr iterator end() const { | |
return Data + Length; | |
} | |
// These are actually the same as iterator, since ArrayRef only | |
// gives you const iterators. | |
constexpr const_iterator cbegin() const { | |
return Data; | |
} | |
constexpr const_iterator cend() const { | |
return Data + Length; | |
} | |
constexpr reverse_iterator rbegin() const { | |
return reverse_iterator(end()); | |
} | |
constexpr reverse_iterator rend() const { | |
return reverse_iterator(begin()); | |
} | |
/// empty - Check if the array is empty. | |
constexpr bool empty() const { | |
return Length == 0; | |
} | |
constexpr const T* data() const { | |
return Data; | |
} | |
/// size - Get the array size. | |
constexpr size_t size() const { | |
return Length; | |
} | |
/// front - Get the first element. | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA const T& front() const { | |
TORCH_CHECK( | |
!empty(), "ArrayRef: attempted to access front() of empty list"); | |
return Data[0]; | |
} | |
/// back - Get the last element. | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA const T& back() const { | |
TORCH_CHECK(!empty(), "ArrayRef: attempted to access back() of empty list"); | |
return Data[Length - 1]; | |
} | |
/// equals - Check for element-wise equality. | |
constexpr bool equals(ArrayRef RHS) const { | |
return Length == RHS.Length && std::equal(begin(), end(), RHS.begin()); | |
} | |
/// slice(n, m) - Take M elements of the array starting at element N | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA ArrayRef<T> slice(size_t N, size_t M) | |
const { | |
TORCH_CHECK( | |
N + M <= size(), | |
"ArrayRef: invalid slice, N = ", | |
N, | |
"; M = ", | |
M, | |
"; size = ", | |
size()); | |
return ArrayRef<T>(data() + N, M); | |
} | |
/// slice(n) - Chop off the first N elements of the array. | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA ArrayRef<T> slice(size_t N) const { | |
TORCH_CHECK( | |
N <= size(), "ArrayRef: invalid slice, N = ", N, "; size = ", size()); | |
return slice(N, size() - N); | |
} | |
/// @} | |
/// @name Operator Overloads | |
/// @{ | |
constexpr const T& operator[](size_t Index) const { | |
return Data[Index]; | |
} | |
/// Vector compatibility | |
C10_HOST_CONSTEXPR_EXCEPT_WIN_CUDA const T& at(size_t Index) const { | |
TORCH_CHECK( | |
Index < Length, | |
"ArrayRef: invalid index Index = ", | |
Index, | |
"; Length = ", | |
Length); | |
return Data[Index]; | |
} | |
/// Disallow accidental assignment from a temporary. | |
/// | |
/// The declaration here is extra complicated so that "arrayRef = {}" | |
/// continues to select the move assignment operator. | |
template <typename U> | |
std::enable_if_t<std::is_same_v<U, T>, ArrayRef<T>>& operator=( | |
// NOLINTNEXTLINE(cppcoreguidelines-missing-std-forward) | |
U&& Temporary) = delete; | |
/// Disallow accidental assignment from a temporary. | |
/// | |
/// The declaration here is extra complicated so that "arrayRef = {}" | |
/// continues to select the move assignment operator. | |
template <typename U> | |
std::enable_if_t<std::is_same_v<U, T>, ArrayRef<T>>& operator=( | |
std::initializer_list<U>) = delete; | |
/// @} | |
/// @name Expensive Operations | |
/// @{ | |
std::vector<T> vec() const { | |
return std::vector<T>(Data, Data + Length); | |
} | |
/// @} | |
}; | |
template <typename T> | |
std::ostream& operator<<(std::ostream& out, ArrayRef<T> list) { | |
int i = 0; | |
out << "["; | |
for (const auto& e : list) { | |
if (i++ > 0) | |
out << ", "; | |
out << e; | |
} | |
out << "]"; | |
return out; | |
} | |
/// @name ArrayRef Convenience constructors | |
/// @{ | |
/// Construct an ArrayRef from a single element. | |
template <typename T> | |
ArrayRef<T> makeArrayRef(const T& OneElt) { | |
return OneElt; | |
} | |
/// Construct an ArrayRef from a pointer and length. | |
template <typename T> | |
ArrayRef<T> makeArrayRef(const T* data, size_t length) { | |
return ArrayRef<T>(data, length); | |
} | |
/// Construct an ArrayRef from a range. | |
template <typename T> | |
ArrayRef<T> makeArrayRef(const T* begin, const T* end) { | |
return ArrayRef<T>(begin, end); | |
} | |
/// Construct an ArrayRef from a SmallVector. | |
template <typename T> | |
ArrayRef<T> makeArrayRef(const SmallVectorImpl<T>& Vec) { | |
return Vec; | |
} | |
/// Construct an ArrayRef from a SmallVector. | |
template <typename T, unsigned N> | |
ArrayRef<T> makeArrayRef(const SmallVector<T, N>& Vec) { | |
return Vec; | |
} | |
/// Construct an ArrayRef from a std::vector. | |
template <typename T> | |
ArrayRef<T> makeArrayRef(const std::vector<T>& Vec) { | |
return Vec; | |
} | |
/// Construct an ArrayRef from a std::array. | |
template <typename T, std::size_t N> | |
ArrayRef<T> makeArrayRef(const std::array<T, N>& Arr) { | |
return Arr; | |
} | |
/// Construct an ArrayRef from an ArrayRef (no-op) (const) | |
template <typename T> | |
ArrayRef<T> makeArrayRef(const ArrayRef<T>& Vec) { | |
return Vec; | |
} | |
/// Construct an ArrayRef from an ArrayRef (no-op) | |
template <typename T> | |
ArrayRef<T>& makeArrayRef(ArrayRef<T>& Vec) { | |
return Vec; | |
} | |
/// Construct an ArrayRef from a C array. | |
template <typename T, size_t N> | |
// NOLINTNEXTLINE(*c-arrays*) | |
ArrayRef<T> makeArrayRef(const T (&Arr)[N]) { | |
return ArrayRef<T>(Arr); | |
} | |
// WARNING: Template instantiation will NOT be willing to do an implicit | |
// conversions to get you to an c10::ArrayRef, which is why we need so | |
// many overloads. | |
template <typename T> | |
bool operator==(c10::ArrayRef<T> a1, c10::ArrayRef<T> a2) { | |
return a1.equals(a2); | |
} | |
template <typename T> | |
bool operator!=(c10::ArrayRef<T> a1, c10::ArrayRef<T> a2) { | |
return !a1.equals(a2); | |
} | |
template <typename T> | |
bool operator==(const std::vector<T>& a1, c10::ArrayRef<T> a2) { | |
return c10::ArrayRef<T>(a1).equals(a2); | |
} | |
template <typename T> | |
bool operator!=(const std::vector<T>& a1, c10::ArrayRef<T> a2) { | |
return !c10::ArrayRef<T>(a1).equals(a2); | |
} | |
template <typename T> | |
bool operator==(c10::ArrayRef<T> a1, const std::vector<T>& a2) { | |
return a1.equals(c10::ArrayRef<T>(a2)); | |
} | |
template <typename T> | |
bool operator!=(c10::ArrayRef<T> a1, const std::vector<T>& a2) { | |
return !a1.equals(c10::ArrayRef<T>(a2)); | |
} | |
using IntArrayRef = ArrayRef<int64_t>; | |
// This alias is deprecated because it doesn't make ownership | |
// semantics obvious. Use IntArrayRef instead! | |
C10_DEFINE_DEPRECATED_USING(IntList, ArrayRef<int64_t>) | |
} // namespace c10 | |