Add util::array - a dynamic array without auto-expansion

This commit is contained in:
Nikita Lisitsa 2025-10-25 15:20:42 +03:00
parent b99a4da18f
commit e40467a8d1
2 changed files with 444 additions and 0 deletions

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#pragma once
#include <psemek/util/exception.hpp>
#include <memory>
#include <cstddef>
#include <algorithm>
#include <format>
#include <initializer_list>
#include <concepts>
namespace psemek::util
{
struct array_index_out_of_bounds
: util::exception
{
array_index_out_of_bounds(std::size_t index, std::size_t size, util::stacktrace stacktrace = {})
: util::exception(std::format("Array index ({}) out of bounds ({})", index, size), std::move(stacktrace))
{}
};
// Like std::vector, but without auto-reallocation and implicit copying
template <typename T>
struct array
{
using value_type = T;
using reference_type = T &;
using pointer_type = T *;
using iterator = T *;
using const_iterator = T const *;
using size_type = std::size_t;
array() = default;
explicit array(std::size_t size);
array(std::size_t size, T const & value);
template <std::input_iterator Iterator>
array(Iterator begin, Iterator end);
array(std::initializer_list<T> const & list);
array(array const & other) = delete;
array(array && other);
array & operator = (array const & other) = delete;
array & operator = (array && other);
std::size_t size() const;
bool empty();
T * data();
T const * data() const;
void resize(std::size_t size);
void resize(std::size_t size, T const & value);
void clear();
void fill(T const & value);
T & operator[] (std::size_t index);
T const & operator[] (std::size_t index) const;
T & at(std::size_t index);
T const & at(std::size_t index) const;
T * begin();
T * end();
T const * begin() const;
T const * end() const;
T const * cbegin() const;
T const * cend() const;
array<T> copy() const;
private:
std::unique_ptr<T[]> data_ = nullptr;
std::size_t size_ = 0;
static std::unique_ptr<T[]> allocate(std::size_t size);
void check_index(std::size_t index);
};
template <typename T>
array<T>::array(std::size_t size)
: data_(allocate(size))
, size_(size)
{}
template <typename T>
array<T>::array(std::size_t size, T const & value)
: data_(allocate(size))
, size_(size)
{
fill(value);
}
template <typename T>
template <std::input_iterator Iterator>
array<T>::array(Iterator begin, Iterator end)
{
size_ = std::distance(begin, end);
data_ = allocate(size_);
std::copy(begin, end, data_.get());
}
template <typename T>
array<T>::array(std::initializer_list<T> const & list)
: data_(allocate(list.size()))
, size_(list.size())
{
std::copy(list.begin(), list.end(), begin());
}
template <typename T>
array<T>::array(array && other)
: data_(std::move(other.data_))
, size_(other.size_)
{
other.size_ = 0;
}
template <typename T>
array<T> & array<T>::operator = (array<T> && other)
{
data_ = std::move(other.data_);
size_ = other.size_;
return *this;
}
template <typename T>
std::size_t array<T>::size() const
{
return size_;
}
template <typename T>
bool array<T>::empty()
{
return size_ == 0;
}
template <typename T>
T * array<T>::data()
{
return data_.get();
}
template <typename T>
T const * array<T>::data() const
{
return data_.get();
}
template <typename T>
void array<T>::resize(std::size_t size)
{
if (size == size_) return;
auto new_data = allocate(size);
std::copy_n(data_.get(), std::min(size, size_), new_data.get());
data_ = std::move(new_data);
size_ = size;
}
template <typename T>
void array<T>::resize(std::size_t size, T const & value)
{
if (size == size_) return;
auto min_size = std::min(size, size_);
auto new_data = allocate(size);
std::copy_n(data_.get(), min_size, new_data.get());
std::fill_n(new_data.get() + min_size, size - min_size, value);
data_ = std::move(new_data);
size_ = size;
}
template <typename T>
void array<T>::clear()
{
data_.reset();
size_ = 0;
}
template <typename T>
void array<T>::fill(T const & value)
{
std::fill(begin(), end(), value);
}
template <typename T>
T & array<T>::operator[] (std::size_t index)
{
return data_[index];
}
template <typename T>
T const & array<T>::operator[] (std::size_t index) const
{
return data_[index];
}
template <typename T>
T & array<T>::at(std::size_t index)
{
check_index(index);
return data_[index];
}
template <typename T>
T const & array<T>::at(std::size_t index) const
{
check_index(index);
return data_[index];
}
template <typename T>
T * array<T>::begin()
{
return data_.get();
}
template <typename T>
T * array<T>::end()
{
return data_.get() + size_;
}
template <typename T>
T const * array<T>::begin() const
{
return data_.get();
}
template <typename T>
T const * array<T>::end() const
{
return data_.get() + size_;
}
template <typename T>
T const * array<T>::cbegin() const
{
return begin();
}
template <typename T>
T const * array<T>::cend() const
{
return end();
}
template <typename T>
array<T> array<T>::copy() const
{
return array<T>(begin(), end());
}
template <typename T>
std::unique_ptr<T[]> array<T>::allocate(std::size_t size)
{
return size == 0 ? nullptr : std::make_unique_for_overwrite<T[]>(size);
}
template <typename T>
void array<T>::check_index(std::size_t index)
{
if (index >= size_)
throw array_index_out_of_bounds(index, size_);
}
}

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libs/util/tests/array.cpp Normal file
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#include <psemek/test/test.hpp>
#include <psemek/util/array.hpp>
using namespace psemek::util;
test_case(util_array_empty)
{
array<int> a;
expect(a.empty());
expect_equal(a.size(), 0);
expect_equal_ptr(a.data(), nullptr);
}
test_case(util_array_ctor_size)
{
array<int> a(16, 42);
expect(!a.empty());
expect_equal(a.size(), 16);
expect_different_ptr(a.data(), nullptr);
for (int i = 0; i < a.size(); ++i)
expect_equal(a[i], 42);
for (int i = 0; i < a.size(); ++i)
a[i] = i;
for (int i = 0; i < a.size(); ++i)
expect_equal(a[i], i);
}
test_case(util_array_ctor_range)
{
int data[8] = {2, 3, 5, 7, 11, 13, 17, 19};
array<int> a(std::begin(data), std::end(data));
expect(!a.empty());
expect_equal(a.size(), std::size(data));
expect_different_ptr(a.data(), nullptr);
for (int i = 0; i < a.size(); ++i)
expect_equal(a[i], data[i]);
}
test_case(util_array_ctor_initializer__list)
{
int data[8] = {2, 3, 5, 7, 11, 13, 17, 19};
array<int> a{2, 3, 5, 7, 11, 13, 17, 19};
expect(!a.empty());
expect_equal(a.size(), std::size(data));
expect_different_ptr(a.data(), nullptr);
for (int i = 0; i < a.size(); ++i)
expect_equal(a[i], data[i]);
}
test_case(util_array_ctor_move)
{
array<int> a(16);
for (int i = 0; i < a.size(); ++i)
a[i] = i;
array<int> b = std::move(a);
expect(a.empty());
expect_equal(a.size(), 0);
expect_equal_ptr(a.data(), nullptr);
expect(!b.empty());
expect_equal(b.size(), 16);
expect_different_ptr(b.data(), nullptr);
for (int i = 0; i < b.size(); ++i)
expect_equal(b[i], i);
}
test_case(util_array_resize)
{
array<int> a(16);
for (int i = 0; i < a.size(); ++i)
a[i] = i;
a.resize(32);
for (int i = 0; i < 16; ++i)
expect_equal(a[i], i);
a.resize(8);
for (int i = 0; i < 8; ++i)
expect_equal(a[i], i);
}
test_case(util_array_clear)
{
array<int> a(16);
a.clear();
expect(a.empty());
expect_equal(a.size(), 0);
expect_equal_ptr(a.data(), nullptr);
}
test_case(util_array_fill)
{
array<int> a(16);
a.fill(42);
for (int i = 0; i < a.size(); ++i)
expect_equal(a[i], 42);
}
test_case(util_array_index)
{
array<int> a(16);
for (int i = 0; i < a.size(); ++i)
expect_equal_ptr(&a[i], a.data() + i);
}
test_case(util_array_at)
{
array<int> a(16);
for (int i = 0; i < a.size(); ++i)
expect_equal_ptr(&a.at(i), a.data() + i);
for (int i = a.size(); i < a.size() + 16; ++i)
expect_throw(a.at(i), array_index_out_of_bounds);
}
test_case(util_array_iterator)
{
array<int> a(16);
for (int i = 0; i < a.size(); ++i)
a[i] = i;
int i = 0;
for (auto v : a)
expect_equal(a[i++], v);
i = 0;
for (auto & v : a)
v = 42 * (i++);
for (int i = 0; i < a.size(); ++i)
expect_equal(a[i], 42 * i);
array<int> const b(a.begin(), a.end());
i = 0;
for (auto v : b)
expect_equal(a[i++], v);
}
test_case(util_array_copy)
{
array<int> a(16);
for (int i = 0; i < a.size(); ++i)
a[i] = i;
auto b = a.copy();
expect_equal(a.size(), b.size());
expect_different_ptr(a.data(), b.data());
for (int i = 0; i < b.size(); ++i)
expect_equal(a[i], b[i]);
}