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// Copyright 2022 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SRC_TINT_UTILS_VECTOR_H_
#define SRC_TINT_UTILS_VECTOR_H_
#include <stddef.h>
#include <stdint.h>
#include <algorithm>
#include <array>
#include <iterator>
#include <ostream>
#include <utility>
#include <vector>
#include "src/tint/castable.h"
#include "src/tint/traits.h"
#include "src/tint/utils/bitcast.h"
#include "src/tint/utils/compiler_macros.h"
#include "src/tint/utils/string.h"
namespace tint::utils {
/// Forward declarations
template <typename>
class VectorRef;
template <typename>
class VectorRef;
} // namespace tint::utils
namespace tint::utils {
/// A type used to indicate an empty array.
struct EmptyType {};
/// An instance of the EmptyType.
static constexpr EmptyType Empty;
/// A slice represents a contigious array of elements of type T.
template <typename T>
struct Slice {
/// The pointer to the first element in the slice
T* data = nullptr;
/// The total number of elements in the slice
size_t len = 0;
/// The total capacity of the backing store for the slice
size_t cap = 0;
/// Index operator
/// @param i the element index. Must be less than `len`.
/// @returns a reference to the i'th element.
T& operator[](size_t i) { return data[i]; }
/// Index operator
/// @param i the element index. Must be less than `len`.
/// @returns a reference to the i'th element.
const T& operator[](size_t i) const { return data[i]; }
/// @returns a reference to the first element in the vector
T& Front() { return data[0]; }
/// @returns a reference to the first element in the vector
const T& Front() const { return data[0]; }
/// @returns a reference to the last element in the vector
T& Back() { return data[len - 1]; }
/// @returns a reference to the last element in the vector
const T& Back() const { return data[len - 1]; }
/// @returns a pointer to the first element in the vector
T* begin() { return data; }
/// @returns a pointer to the first element in the vector
const T* begin() const { return data; }
/// @returns a pointer to one past the last element in the vector
T* end() { return data + len; }
/// @returns a pointer to one past the last element in the vector
const T* end() const { return data + len; }
/// @returns a reverse iterator starting with the last element in the vector
auto rbegin() { return std::reverse_iterator<T*>(end()); }
/// @returns a reverse iterator starting with the last element in the vector
auto rbegin() const { return std::reverse_iterator<const T*>(end()); }
/// @returns the end for a reverse iterator
auto rend() { return std::reverse_iterator<T*>(begin()); }
/// @returns the end for a reverse iterator
auto rend() const { return std::reverse_iterator<const T*>(begin()); }
};
/// Mode enumerator for ReinterpretSlice
enum class ReinterpretMode {
/// Only upcasts of pointers are permitted
kSafe,
/// Potentially unsafe downcasts of pointers are also permitted
kUnsafe,
};
namespace detail {
/// Private implementation of tint::utils::CanReinterpretSlice.
/// Specialized for the case of TO equal to FROM, which is the common case, and avoids inspection of
/// the base classes, which can be troublesome if the slice is of an incomplete type.
template <ReinterpretMode MODE, typename TO, typename FROM>
struct CanReinterpretSlice {
/// True if a slice of FROM can be reinterpreted as a slice of TO
static constexpr bool value =
// Both TO and FROM are pointers
(std::is_pointer_v<TO> && std::is_pointer_v<FROM>)&& //
// const can only be applied, not removed
(std::is_const_v<std::remove_pointer_t<TO>> ||
!std::is_const_v<std::remove_pointer_t<FROM>>)&& //
// TO and FROM are both Castable
IsCastable<std::remove_pointer_t<FROM>, std::remove_pointer_t<TO>> && //
// MODE is kUnsafe, or FROM is of, or derives from TO
(MODE == ReinterpretMode::kUnsafe ||
traits::IsTypeOrDerived<std::remove_pointer_t<FROM>, std::remove_pointer_t<TO>>);
};
/// Specialization of 'CanReinterpretSlice' for when TO and FROM are equal types.
template <typename T, ReinterpretMode MODE>
struct CanReinterpretSlice<MODE, T, T> {
/// Always `true` as TO and FROM are the same type.
static constexpr bool value = true;
};
} // namespace detail
/// Evaluates whether a `vector<FROM>` and be reinterpreted as a `vector<TO>`.
/// Vectors can be reinterpreted if both `FROM` and `TO` are pointers to a type that derives from
/// CastableBase, and the pointee type of `TO` is of the same type as, or is an ancestor of the
/// pointee type of `FROM`. Vectors of non-`const` Castable pointers can be converted to a vector of
/// `const` Castable pointers.
template <ReinterpretMode MODE, typename TO, typename FROM>
static constexpr bool CanReinterpretSlice = detail::CanReinterpretSlice<MODE, TO, FROM>::value;
/// Reinterprets `const Slice<FROM>*` as `const Slice<TO>*`
/// @param slice a pointer to the slice to reinterpret
/// @returns the reinterpreted slice
/// @see CanReinterpretSlice
template <ReinterpretMode MODE, typename TO, typename FROM>
const Slice<TO>* ReinterpretSlice(const Slice<FROM>* slice) {
static_assert(CanReinterpretSlice<MODE, TO, FROM>);
return Bitcast<const Slice<TO>*>(slice);
}
/// Reinterprets `Slice<FROM>*` as `Slice<TO>*`
/// @param slice a pointer to the slice to reinterpret
/// @returns the reinterpreted slice
/// @see CanReinterpretSlice
template <ReinterpretMode MODE, typename TO, typename FROM>
Slice<TO>* ReinterpretSlice(Slice<FROM>* slice) {
static_assert(CanReinterpretSlice<MODE, TO, FROM>);
return Bitcast<Slice<TO>*>(slice);
}
/// Vector is a small-object-optimized, dynamically-sized vector of contigious elements of type T.
///
/// Vector will fit `N` elements internally before spilling to heap allocations. If `N` is greater
/// than zero, the internal elements are stored in a 'small array' held internally by the Vector.
///
/// Vectors can be copied or moved.
///
/// Copying a vector will either copy to the 'small array' if the number of elements is equal to or
/// less than N, otherwise elements will be copied into a new heap allocation.
///
/// Moving a vector will reassign ownership of the heap-allocation memory, if the source vector
/// holds its elements in a heap allocation, otherwise a copy will be made as described above.
///
/// Vector is optimized for CPU performance over memory efficiency. For example:
/// * Moving a vector that stores its elements in a heap allocation to another vector will simply
/// assign the heap allocation, even if the target vector can hold the elements in its 'small
/// array'. This reduces memory copying, but may incur additional memory usage.
/// * Resizing, or popping elements from a vector that has spilled to a heap allocation does not
/// revert back to using the 'small array'. Again, this is to reduce memory copying.
template <typename T, size_t N>
class Vector {
public:
/// Type of `T`.
using value_type = T;
/// Value of `N`
static constexpr size_t static_length = N;
/// Constructor
Vector() = default;
/// Constructor
Vector(EmptyType) {} // NOLINT(runtime/explicit)
/// Constructor
/// @param elements the elements to place into the vector
Vector(std::initializer_list<T> elements) {
Reserve(elements.size());
for (auto& el : elements) {
new (&impl_.slice.data[impl_.slice.len++]) T{el};
}
}
/// Copy constructor
/// @param other the vector to copy
Vector(const Vector& other) { Copy(other.impl_.slice); }
/// Move constructor
/// @param other the vector to move
Vector(Vector&& other) { MoveOrCopy(VectorRef<T>(std::move(other))); }
/// Copy constructor (differing N length)
/// @param other the vector to copy
template <size_t N2>
Vector(const Vector<T, N2>& other) {
Copy(other.impl_.slice);
}
/// Move constructor (differing N length)
/// @param other the vector to move
template <size_t N2>
Vector(Vector<T, N2>&& other) {
MoveOrCopy(VectorRef<T>(std::move(other)));
}
/// Copy constructor with covariance / const conversion
/// @param other the vector to copy
/// @see CanReinterpretSlice for rules about conversion
template <typename U,
size_t N2,
ReinterpretMode MODE,
typename = std::enable_if_t<CanReinterpretSlice<MODE, T, U>>>
Vector(const Vector<U, N2>& other) { // NOLINT(runtime/explicit)
Copy(*ReinterpretSlice<MODE, T>(&other.impl_.slice));
}
/// Move constructor with covariance / const conversion
/// @param other the vector to move
/// @see CanReinterpretSlice for rules about conversion
template <typename U,
size_t N2,
ReinterpretMode MODE,
typename = std::enable_if_t<CanReinterpretSlice<MODE, T, U>>>
Vector(Vector<U, N2>&& other) { // NOLINT(runtime/explicit)
MoveOrCopy(VectorRef<T>(std::move(other)));
}
/// Move constructor from a mutable vector reference
/// @param other the vector reference to move
Vector(VectorRef<T>&& other) { MoveOrCopy(std::move(other)); } // NOLINT(runtime/explicit)
/// Copy constructor from an immutable vector reference
/// @param other the vector reference to copy
Vector(const VectorRef<T>& other) { Copy(other.slice_); } // NOLINT(runtime/explicit)
/// Destructor
~Vector() { ClearAndFree(); }
/// Assignment operator
/// @param other the vector to copy
/// @returns this vector so calls can be chained
Vector& operator=(const Vector& other) {
if (&other != this) {
Copy(other.impl_.slice);
}
return *this;
}
/// Move operator
/// @param other the vector to move
/// @returns this vector so calls can be chained
Vector& operator=(Vector&& other) {
if (&other != this) {
MoveOrCopy(VectorRef<T>(std::move(other)));
}
return *this;
}
/// Assignment operator (differing N length)
/// @param other the vector to copy
/// @returns this vector so calls can be chained
template <size_t N2>
Vector& operator=(const Vector<T, N2>& other) {
Copy(other.impl_.slice);
return *this;
}
/// Move operator (differing N length)
/// @param other the vector to copy
/// @returns this vector so calls can be chained
template <size_t N2>
Vector& operator=(Vector<T, N2>&& other) {
MoveOrCopy(VectorRef<T>(std::move(other)));
return *this;
}
/// Assignment operator (differing N length)
/// @param other the vector reference to copy
/// @returns this vector so calls can be chained
Vector& operator=(const VectorRef<T>& other) {
if (&other.slice_ != &impl_.slice) {
Copy(other.slice_);
}
return *this;
}
/// Move operator (differing N length)
/// @param other the vector reference to copy
/// @returns this vector so calls can be chained
Vector& operator=(VectorRef<T>&& other) {
if (&other.slice_ != &impl_.slice) {
MoveOrCopy(std::move(other));
}
return *this;
}
/// Index operator
/// @param i the element index. Must be less than `len`.
/// @returns a reference to the i'th element.
T& operator[](size_t i) { return impl_.slice[i]; }
/// Index operator
/// @param i the element index. Must be less than `len`.
/// @returns a reference to the i'th element.
const T& operator[](size_t i) const { return impl_.slice[i]; }
/// @return the number of elements in the vector
size_t Length() const { return impl_.slice.len; }
/// @return the number of elements that the vector could hold before a heap allocation needs to
/// be made
size_t Capacity() const { return impl_.slice.cap; }
/// Reserves memory to hold at least `new_cap` elements
/// @param new_cap the new vector capacity
void Reserve(size_t new_cap) {
if (new_cap > impl_.slice.cap) {
auto* old_data = impl_.slice.data;
impl_.Allocate(new_cap);
for (size_t i = 0; i < impl_.slice.len; i++) {
new (&impl_.slice.data[i]) T(std::move(old_data[i]));
old_data[i].~T();
}
impl_.Free(old_data);
}
}
/// Resizes the vector to the given length, expanding capacity if necessary.
/// New elements are zero-initialized
/// @param new_len the new vector length
void Resize(size_t new_len) {
Reserve(new_len);
for (size_t i = impl_.slice.len; i > new_len; i--) { // Shrink
impl_.slice.data[i - 1].~T();
}
for (size_t i = impl_.slice.len; i < new_len; i++) { // Grow
new (&impl_.slice.data[i]) T{};
}
impl_.slice.len = new_len;
}
/// Resizes the vector to the given length, expanding capacity if necessary.
/// @param new_len the new vector length
/// @param value the value to copy into the new elements
void Resize(size_t new_len, const T& value) {
Reserve(new_len);
for (size_t i = impl_.slice.len; i > new_len; i--) { // Shrink
impl_.slice.data[i - 1].~T();
}
for (size_t i = impl_.slice.len; i < new_len; i++) { // Grow
new (&impl_.slice.data[i]) T{value};
}
impl_.slice.len = new_len;
}
/// Copies all the elements from `other` to this vector, replacing the content of this vector.
/// @param other the
template <typename T2, size_t N2>
void Copy(const Vector<T2, N2>& other) {
Copy(other.impl_.slice);
}
/// Clears all elements from the vector, keeping the capacity the same.
void Clear() {
TINT_BEGIN_DISABLE_WARNING(MAYBE_UNINITIALIZED);
for (size_t i = 0; i < impl_.slice.len; i++) {
impl_.slice.data[i].~T();
}
impl_.slice.len = 0;
TINT_END_DISABLE_WARNING(MAYBE_UNINITIALIZED);
}
/// Appends a new element to the vector.
/// @param el the element to copy to the vector.
void Push(const T& el) {
if (impl_.slice.len >= impl_.slice.cap) {
Grow();
}
new (&impl_.slice.data[impl_.slice.len++]) T(el);
}
/// Appends a new element to the vector.
/// @param el the element to move to the vector.
void Push(T&& el) {
if (impl_.slice.len >= impl_.slice.cap) {
Grow();
}
new (&impl_.slice.data[impl_.slice.len++]) T(std::move(el));
}
/// Appends a new element to the vector.
/// @param args the arguments to pass to the element constructor.
template <typename... ARGS>
void Emplace(ARGS&&... args) {
if (impl_.slice.len >= impl_.slice.cap) {
Grow();
}
new (&impl_.slice.data[impl_.slice.len++]) T{std::forward<ARGS>(args)...};
}
/// Removes and returns the last element from the vector.
/// @returns the popped element
T Pop() {
auto& el = impl_.slice.data[--impl_.slice.len];
auto val = std::move(el);
el.~T();
return val;
}
/// Sort sorts the vector in-place using the predicate function @p pred
/// @param pred a function that has the signature `bool(const T& a, const T& b)` which returns
/// true if `a` is ordered before `b`.
template <typename PREDICATE>
void Sort(PREDICATE&& pred) {
std::sort(begin(), end(), std::forward<PREDICATE>(pred));
}
/// Sort sorts the vector in-place using `T::operator<()`
void Sort() {
Sort([](auto& a, auto& b) { return a < b; });
}
/// @returns true if the vector is empty.
bool IsEmpty() const { return impl_.slice.len == 0; }
/// @returns a reference to the first element in the vector
T& Front() { return impl_.slice.Front(); }
/// @returns a reference to the first element in the vector
const T& Front() const { return impl_.slice.Front(); }
/// @returns a reference to the last element in the vector
T& Back() { return impl_.slice.Back(); }
/// @returns a reference to the last element in the vector
const T& Back() const { return impl_.slice.Back(); }
/// @returns a pointer to the first element in the vector
T* begin() { return impl_.slice.begin(); }
/// @returns a pointer to the first element in the vector
const T* begin() const { return impl_.slice.begin(); }
/// @returns a pointer to one past the last element in the vector
T* end() { return impl_.slice.end(); }
/// @returns a pointer to one past the last element in the vector
const T* end() const { return impl_.slice.end(); }
/// @returns a reverse iterator starting with the last element in the vector
auto rbegin() { return impl_.slice.rbegin(); }
/// @returns a reverse iterator starting with the last element in the vector
auto rbegin() const { return impl_.slice.rbegin(); }
/// @returns the end for a reverse iterator
auto rend() { return impl_.slice.rend(); }
/// @returns the end for a reverse iterator
auto rend() const { return impl_.slice.rend(); }
/// Equality operator
/// @param other the other vector
/// @returns true if this vector is the same length as `other`, and all elements are equal.
template <typename T2, size_t N2>
bool operator==(const Vector<T2, N2>& other) const {
const size_t len = Length();
if (len != other.Length()) {
return false;
}
for (size_t i = 0; i < len; i++) {
if ((*this)[i] != other[i]) {
return false;
}
}
return true;
}
/// Inequality operator
/// @param other the other vector
/// @returns true if this vector is not the same length as `other`, or all elements are not
/// equal.
template <typename T2, size_t N2>
bool operator!=(const Vector<T2, N2>& other) const {
return !(*this == other);
}
private:
/// Friend class (differing specializations of this class)
template <typename, size_t>
friend class Vector;
/// Friend class
template <typename>
friend class VectorRef;
/// Friend class
template <typename>
friend class VectorRef;
/// The slice type used by this vector
using Slice = utils::Slice<T>;
template <typename... Ts>
void AppendVariadic(Ts&&... args) {
((new (&impl_.slice.data[impl_.slice.len++]) T(std::forward<Ts>(args))), ...);
}
/// Expands the capacity of the vector
void Grow() { Reserve(std::max(impl_.slice.cap, static_cast<size_t>(1)) * 2); }
/// Moves 'other' to this vector, if possible, otherwise performs a copy.
void MoveOrCopy(VectorRef<T>&& other) {
if (other.can_move_) {
ClearAndFree();
impl_.slice = other.slice_;
other.slice_ = {};
} else {
Copy(other.slice_);
}
}
/// Copies all the elements from `other` to this vector, replacing the content of this vector.
/// @param other the
void Copy(const Slice& other) {
if (impl_.slice.cap < other.len) {
ClearAndFree();
impl_.Allocate(other.len);
} else {
Clear();
}
impl_.slice.len = other.len;
for (size_t i = 0; i < impl_.slice.len; i++) {
new (&impl_.slice.data[i]) T{other.data[i]};
}
}
/// Clears the vector, then frees the slice data.
void ClearAndFree() {
Clear();
impl_.Free(impl_.slice.data);
}
/// True if this vector uses a small array for small object optimization.
constexpr static bool HasSmallArray = N > 0;
/// A structure that has the same size and alignment as T.
/// Replacement for std::aligned_storage as this is broken on earlier versions of MSVC.
struct alignas(alignof(T)) TStorage {
/// @returns the storage reinterpreted as a T*
T* Get() { return Bitcast<T*>(&data[0]); }
/// @returns the storage reinterpreted as a T*
const T* Get() const { return Bitcast<const T*>(&data[0]); }
/// Byte array of length sizeof(T)
uint8_t data[sizeof(T)];
};
/// The internal structure for the vector with a small array.
struct ImplWithSmallArray {
std::array<TStorage, N> small_arr;
Slice slice = {small_arr[0].Get(), 0, N};
/// Allocates a new vector of `T` either from #small_arr, or from the heap, then assigns the
/// pointer it to #slice.data, and updates #slice.cap.
void Allocate(size_t new_cap) {
if (new_cap < N) {
slice.data = small_arr[0].Get();
slice.cap = N;
} else {
slice.data = Bitcast<T*>(new TStorage[new_cap]);
slice.cap = new_cap;
}
}
/// Frees `data`, if not nullptr and isn't a pointer to #small_arr
void Free(T* data) const {
if (data && data != small_arr[0].Get()) {
delete[] Bitcast<TStorage*>(data);
}
}
/// Indicates whether the slice structure can be std::move()d.
/// @returns true if #slice.data does not point to #small_arr
bool CanMove() const { return slice.data != small_arr[0].Get(); }
};
/// The internal structure for the vector without a small array.
struct ImplWithoutSmallArray {
Slice slice = {nullptr, 0, 0};
/// Allocates a new vector of `T` and assigns it to #slice.data, and updates #slice.cap.
void Allocate(size_t new_cap) {
slice.data = Bitcast<T*>(new TStorage[new_cap]);
slice.cap = new_cap;
}
/// Frees `data`, if not nullptr.
void Free(T* data) const {
if (data) {
delete[] Bitcast<TStorage*>(data);
}
}
/// Indicates whether the slice structure can be std::move()d.
/// @returns true
bool CanMove() const { return true; }
};
/// Either a ImplWithSmallArray or ImplWithoutSmallArray based on N.
std::conditional_t<HasSmallArray, ImplWithSmallArray, ImplWithoutSmallArray> impl_;
};
namespace detail {
/// Helper for determining the Vector element type (`T`) from the vector's constuctor arguments
/// @tparam IS_CASTABLE true if the types of `Ts` derive from CastableBase
/// @tparam Ts the vector constructor argument types to infer the vector element type from.
template <bool IS_CASTABLE, typename... Ts>
struct VectorCommonType;
/// VectorCommonType specialization for non-castable types.
template <typename... Ts>
struct VectorCommonType</*IS_CASTABLE*/ false, Ts...> {
/// The common T type to use for the vector
using type = std::common_type_t<Ts...>;
};
/// VectorCommonType specialization for castable types.
template <typename... Ts>
struct VectorCommonType</*IS_CASTABLE*/ true, Ts...> {
/// The common Castable type (excluding pointer)
using common_ty = CastableCommonBase<std::remove_pointer_t<Ts>...>;
/// The common T type to use for the vector
using type = std::conditional_t<(std::is_const_v<std::remove_pointer_t<Ts>> || ...),
const common_ty*,
common_ty*>;
};
} // namespace detail
/// Helper for determining the Vector element type (`T`) from the vector's constuctor arguments
template <typename... Ts>
using VectorCommonType =
typename detail::VectorCommonType<IsCastable<std::remove_pointer_t<Ts>...>, Ts...>::type;
/// Deduction guide for Vector
template <typename... Ts>
Vector(Ts...) -> Vector<VectorCommonType<Ts...>, sizeof...(Ts)>;
/// VectorRef is a weak reference to a Vector, used to pass vectors as parameters, avoiding copies
/// between the caller and the callee, or as an non-static sized accessor on a vector. VectorRef can
/// accept a Vector of any 'N' value, decoupling the caller's vector internal size from the callee's
/// vector size. A VectorRef tracks the usage of moves either side of the call. If at the call site,
/// a Vector argument is moved to a VectorRef parameter, and within the callee, the VectorRef
/// parameter is moved to a Vector, then the Vector heap allocation will be moved. For example:
///
/// ```
/// void func_a() {
/// Vector<std::string, 4> vec;
/// // logic to populate 'vec'.
/// func_b(std::move(vec)); // Constructs a VectorRef tracking the move here.
/// }
///
/// void func_b(VectorRef<std::string> vec_ref) {
/// // A move was made when calling func_b, so the vector can be moved instead of copied.
/// Vector<std::string, 2> vec(std::move(vec_ref));
/// }
/// ```
///
/// Aside from this move pattern, a VectorRef provides an immutable reference to the Vector.
template <typename T>
class VectorRef {
/// The slice type used by this vector reference
using Slice = utils::Slice<T>;
/// @returns an empty slice.
static Slice& EmptySlice() {
static Slice empty;
return empty;
}
public:
/// Type of `T`.
using value_type = T;
/// Constructor - empty reference
VectorRef() : slice_(EmptySlice()) {}
/// Constructor
VectorRef(EmptyType) : slice_(EmptySlice()) {} // NOLINT(runtime/explicit)
/// Constructor from a Slice
/// @param slice the slice
VectorRef(Slice& slice) // NOLINT(runtime/explicit)
: slice_(slice) {}
/// Constructor from a Vector
/// @param vector the vector to create a reference of
template <size_t N>
VectorRef(Vector<T, N>& vector) // NOLINT(runtime/explicit)
: slice_(vector.impl_.slice) {}
/// Constructor from a const Vector
/// @param vector the vector to create a reference of
template <size_t N>
VectorRef(const Vector<T, N>& vector) // NOLINT(runtime/explicit)
: slice_(const_cast<Slice&>(vector.impl_.slice)) {}
/// Constructor from a moved Vector
/// @param vector the vector being moved
template <size_t N>
VectorRef(Vector<T, N>&& vector) // NOLINT(runtime/explicit)
: slice_(vector.impl_.slice), can_move_(vector.impl_.CanMove()) {}
/// Copy constructor
/// @param other the vector reference
VectorRef(const VectorRef& other) : slice_(other.slice_) {}
/// Move constructor
/// @param other the vector reference
VectorRef(VectorRef&& other) = default;
/// Copy constructor with covariance / const conversion
/// @param other the other vector reference
template <typename U,
typename = std::enable_if_t<CanReinterpretSlice<ReinterpretMode::kSafe, T, U>>>
VectorRef(const VectorRef<U>& other) // NOLINT(runtime/explicit)
: slice_(*ReinterpretSlice<ReinterpretMode::kSafe, T>(&other.slice_)) {}
/// Move constructor with covariance / const conversion
/// @param other the vector reference
template <typename U,
typename = std::enable_if_t<CanReinterpretSlice<ReinterpretMode::kSafe, T, U>>>
VectorRef(VectorRef<U>&& other) // NOLINT(runtime/explicit)
: slice_(*ReinterpretSlice<ReinterpretMode::kSafe, T>(&other.slice_)),
can_move_(other.can_move_) {}
/// Constructor from a Vector with covariance / const conversion
/// @param vector the vector to create a reference of
/// @see CanReinterpretSlice for rules about conversion
template <typename U,
size_t N,
typename = std::enable_if_t<CanReinterpretSlice<ReinterpretMode::kSafe, T, U>>>
VectorRef(Vector<U, N>& vector) // NOLINT(runtime/explicit)
: slice_(*ReinterpretSlice<ReinterpretMode::kSafe, T>(&vector.impl_.slice)) {}
/// Constructor from a moved Vector with covariance / const conversion
/// @param vector the vector to create a reference of
/// @see CanReinterpretSlice for rules about conversion
template <typename U,
size_t N,
typename = std::enable_if_t<CanReinterpretSlice<ReinterpretMode::kSafe, T, U>>>
VectorRef(Vector<U, N>&& vector) // NOLINT(runtime/explicit)
: slice_(*ReinterpretSlice<ReinterpretMode::kSafe, T>(&vector.impl_.slice)),
can_move_(vector.impl_.CanMove()) {}
/// Index operator
/// @param i the element index. Must be less than `len`.
/// @returns a reference to the i'th element.
const T& operator[](size_t i) const { return slice_[i]; }
/// @return the number of elements in the vector
size_t Length() const { return slice_.len; }
/// @return the number of elements that the vector could hold before a heap allocation needs to
/// be made
size_t Capacity() const { return slice_.cap; }
/// @return a reinterpretation of this VectorRef as elements of type U.
/// @note this is doing a reinterpret_cast of elements. It is up to the caller to ensure that
/// this is a safe operation.
template <typename U>
VectorRef<U> ReinterpretCast() const {
return {*ReinterpretSlice<ReinterpretMode::kUnsafe, U>(&slice_)};
}
/// @returns true if the vector is empty.
bool IsEmpty() const { return slice_.len == 0; }
/// @returns a reference to the first element in the vector
const T& Front() const { return slice_.Front(); }
/// @returns a reference to the last element in the vector
const T& Back() const { return slice_.Back(); }
/// @returns a pointer to the first element in the vector
const T* begin() const { return slice_.begin(); }
/// @returns a pointer to one past the last element in the vector
const T* end() const { return slice_.end(); }
/// @returns a reverse iterator starting with the last element in the vector
auto rbegin() const { return slice_.rbegin(); }
/// @returns the end for a reverse iterator
auto rend() const { return slice_.rend(); }
private:
/// Friend class
template <typename, size_t>
friend class Vector;
/// Friend class
template <typename>
friend class VectorRef;
/// Friend class
template <typename>
friend class VectorRef;
/// The slice of the vector being referenced.
Slice& slice_;
/// Whether the slice data is passed by r-value reference, and can be moved.
bool can_move_ = false;
};
/// Helper for converting a Vector to a std::vector.
/// @note This helper exists to help code migration. Avoid if possible.
template <typename T, size_t N>
std::vector<T> ToStdVector(const Vector<T, N>& vector) {
std::vector<T> out;
out.reserve(vector.Length());
for (auto& el : vector) {
out.emplace_back(el);
}
return out;
}
/// Helper for converting a std::vector to a Vector.
/// @note This helper exists to help code migration. Avoid if possible.
template <typename T, size_t N = 0>
Vector<T, N> ToVector(const std::vector<T>& vector) {
Vector<T, N> out;
out.Reserve(vector.size());
for (auto& el : vector) {
out.Push(el);
}
return out;
}
/// Prints the vector @p vec to @p o
/// @param o the std::ostream to write to
/// @param vec the vector
/// @return the std::ostream so calls can be chained
template <typename T, size_t N>
inline std::ostream& operator<<(std::ostream& o, const utils::Vector<T, N>& vec) {
o << "[";
bool first = true;
for (auto& el : vec) {
if (!first) {
o << ", ";
}
first = false;
o << ToString(el);
}
o << "]";
return o;
}
/// Prints the vector @p vec to @p o
/// @param o the std::ostream to write to
/// @param vec the vector reference
/// @return the std::ostream so calls can be chained
template <typename T>
inline std::ostream& operator<<(std::ostream& o, utils::VectorRef<T> vec) {
o << "[";
bool first = true;
for (auto& el : vec) {
if (!first) {
o << ", ";
}
first = false;
o << ToString(el);
}
o << "]";
return o;
}
} // namespace tint::utils
#endif // SRC_TINT_UTILS_VECTOR_H_