co-cpp19/src/array19.lib/array19/AllocatedArrayUtils.h at develop · basicpp/co-cpp19 · GitHub

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#pragma once

#include "MoveSliceOf.h"

#include "SliceOf.h"

#include <new> // ::operator new, ::operator delete

#include <stddef.h> // size_t

#include <string.h> // memcpy

#include <type_traits>

#include <utility>

namespace array19 {

/// Utility functions that implement the meat of allocated arrays

///

/// note:

/// * This replaces the algorithmns form std <memory> header.

/// * It works with Slices instead of iterators to simplify the interface

template<class T> struct AllocatedArrayUtils {

static_assert(std::is_nothrow_move_constructible_v<T>, "Please ensure move constructior is marked noexcept!");

static_assert(std::is_nothrow_move_assignable_v<T>, "Please ensure move assignment is marked noexcept!");

static_assert(std::is_nothrow_destructible_v<T>, "Please ensure destructor is marked noexcept!");

using Slice = SliceOf<T>;

using ConstSlice = SliceOf<const T>;

using MoveSlice = MoveSliceOf<T>;

/// returns uninitialized storage for \param count elements with proper alignment

/// note:

/// * use deallocate to free the storage!

/// * exceptions from new will terminate - without memory no recovery is possible!

[[nodiscard]] static auto allocate(size_t count) noexcept -> T* {

if (0 == count) return nullptr;

if constexpr (__STDCPP_DEFAULT_NEW_ALIGNMENT__ < alignof(T)) {

return reinterpret_cast<T*>(::operator new[](count * sizeof(T), std::align_val_t{alignof(T)}));

}

else {

return reinterpret_cast<T*>(::operator new[](count * sizeof(T)));

}

/// frees the storage pointed to by the slice

/// note:

/// * slice.begin() has to be the pointer returned by allocate(size.count())

/// * exceptions form delete will terminate - we assume memory is corrupted!

static void deallocate(Slice slice) noexcept {

#if __cpp_sized_deallocation

if constexpr (__STDCPP_DEFAULT_NEW_ALIGNMENT__ < alignof(T)) {

::operator delete[](slice.begin(), slice.count() * sizeof(T), std::align_val_t{alignof(T)});

}

else {

::operator delete[](slice.begin(), slice.count() * sizeof(T));

}

#else

if constexpr (__STDCPP_DEFAULT_NEW_ALIGNMENT__ < alignof(T)) {

::operator delete[](slice.begin(), std::align_val_t{alignof(T)});

}

else {

::operator delete[](slice.begin());

}

#endif

}

/// default construct every element of \param slice if necessary

static void defaultConstruct(Slice slice) noexcept(std::is_nothrow_default_constructible_v<T>) {

if constexpr (!std::is_trivially_default_constructible_v<T>)

for (auto& e : slice) new (&e) T();

}

/// calls destructor for every element of \param slice if necessary

/// note:

/// * we assume destructors are always noexcept

static void destruct(Slice slice) noexcept {

if constexpr (!std::is_trivially_destructible_v<T>)

for (auto& elem : slice) elem.~T();

}

/// constructs a copy of \param fromSlice at \param toPointer

/// note:

/// * toPointer has to point to least fromSlice.count() elements

/// * assumes toPointer and fromSlice do not overlap

static void copyConstruct(T* toPointer, ConstSlice fromSlice) noexcept(std::is_nothrow_copy_constructible_v<T>) {

if constexpr (std::is_trivially_copy_constructible_v<T>) {

if (!fromSlice.isEmpty()) {

memcpy(toPointer, fromSlice.begin(), fromSlice.count() * sizeof(T));

}

else {

for (auto& from : fromSlice) new (toPointer++) T(from);

}

/// move constructs elements of \param fromSlice into \param to Pointer

/// note:

/// * toPointer has to point to least fromSlice.count() elements

/// * assumes toPointer and fromSlice do not overlap

/// * we assume move is always noexcept!

static void moveConstruct(T* toPointer, MoveSlice fromSlice) noexcept {

if constexpr (std::is_trivially_move_constructible_v<T>) {

if (!fromSlice.isEmpty()) {

memcpy(toPointer, fromSlice.begin(), fromSlice.count() * sizeof(T));

}

else {

for (auto& from : fromSlice) new (toPointer++) T(std::move(from));

}

/// assigns elements of \param fromSlice into \param toPointer

/// note:

/// * toPointer has to point to least fromSlice.count() initialized elements

/// * assumes toPointer and fromSlice do not overlap

static void copyAssign(T* toPointer, ConstSlice fromSlice) noexcept(std::is_nothrow_copy_assignable_v<T>) {

if constexpr (std::is_trivially_copy_assignable_v<T>) {

if (!fromSlice.isEmpty()) {

memcpy(toPointer, fromSlice.begin(), fromSlice.count() * sizeof(T));

}

else {

for (const auto& from : fromSlice) *toPointer++ = from;

}

/// move assigns elements of \param fromSlice into \param to Pointer

/// note:

/// * toPointer has to point to least fromSlice.count() elements

/// * assumes toPointer and fromSlice do not overlap

/// * we assume move is always noexcept!

static void moveAssign(T* toPointer, MoveSlice fromSlice) noexcept {

if constexpr (std::is_trivially_move_assignable_v<T>) {

if (!fromSlice.isEmpty()) {

memcpy(toPointer, fromSlice.begin(), fromSlice.count() * sizeof(T));

}

else {

for (auto& from : fromSlice) *toPointer++ = std::move(from);

}

/// move assigns elements of \param fromSlice into \param to Pointer

/// note:

/// * toPointer has to point to least fromSlice.count() elements

/// * toPointer has to be before fromSlice.begin() if ranges overlap

/// * we assume move is always noexcept!

///

/// example:

/// [ e e e e e e e ]

/// toPointer ^ ^ fromSlice.begin()

static void moveAssignForward(T* toPointer, MoveSlice fromSlice) noexcept {

if constexpr (std::is_trivially_move_constructible_v<T>) {

if (!fromSlice.isEmpty()) {

memmove(toPointer, fromSlice.begin(), fromSlice.count() * sizeof(T));

}

else {

for (auto& from : fromSlice) *toPointer++ = std::move(from);

}

/// move assigns elements of \param fromSlice into \param to Pointer

/// note:

/// * toPointer has to point to least fromSlice.count() elements

/// * toPointer has to be behind fromSlice.begin() if ranges overlap

/// * we assume move is always noexcept!

///

/// example:

/// [ e e e e e e e ]

/// fromSlice.begin() ^ ^ toPointer

static void moveAssignReverse(T* toPointer, MoveSlice fromSlice) noexcept {

if constexpr (std::is_trivially_move_assignable_v<T>) {

if (!fromSlice.isEmpty()) {

memmove(toPointer, fromSlice.begin(), fromSlice.count() * sizeof(T));

}

else {

auto rTo = toPointer + fromSlice.count();

auto rFrom = fromSlice.end();

auto rFromEnd = fromSlice.begin();

while (rFrom != rFromEnd) *(--rTo) = std::move(*(--rFrom));

}

};

} // namespace array19

co-cpp19/src/array19.lib/array19/AllocatedArrayUtils.h at develop · basicpp/co-cpp19 · GitHub

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