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Diffstat (limited to 'immer/array.hpp')
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diff --git a/immer/array.hpp b/immer/array.hpp new file mode 100644 index 000000000000..24c8f84c8bbf --- /dev/null +++ b/immer/array.hpp @@ -0,0 +1,364 @@ +// +// immer: immutable data structures for C++ +// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente +// +// This software is distributed under the Boost Software License, Version 1.0. +// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt +// + +#pragma once + +#include <immer/detail/arrays/with_capacity.hpp> +#include <immer/memory_policy.hpp> + +namespace immer { + +template <typename T, typename MemoryPolicy> +class array_transient; + +/*! + * Immutable container that stores a sequence of elements in + * contiguous memory. + * + * @tparam T The type of the values to be stored in the container. + * + * @rst + * + * It supports the most efficient iteration and random access, + * equivalent to a ``std::vector`` or ``std::array``, but all + * manipulations are :math:`O(size)`. + * + * .. tip:: Don't be fooled by the bad complexity of this data + * structure. It is a great choice for short sequence or when it + * is seldom or never changed. This depends on the ``sizeof(T)`` + * and the expensiveness of its ``T``'s copy constructor, in case + * of doubt, measure. For basic types, using an `array` when + * :math:`n < 100` is a good heuristic. + * + * @endrst + */ +template <typename T, typename MemoryPolicy = default_memory_policy> +class array +{ + using impl_t = + std::conditional_t<MemoryPolicy::use_transient_rvalues, + detail::arrays::with_capacity<T, MemoryPolicy>, + detail::arrays::no_capacity<T, MemoryPolicy>>; + + using move_t = + std::integral_constant<bool, MemoryPolicy::use_transient_rvalues>; + +public: + using value_type = T; + using reference = const T&; + using size_type = std::size_t; + using difference_type = std::ptrdiff_t; + using const_reference = const T&; + + using iterator = const T*; + using const_iterator = iterator; + using reverse_iterator = std::reverse_iterator<iterator>; + + using memory_policy = MemoryPolicy; + using transient_type = array_transient<T, MemoryPolicy>; + + /*! + * Default constructor. It creates an array of `size() == 0`. It + * does not allocate memory and its complexity is @f$ O(1) @f$. + */ + array() = default; + + /*! + * Constructs an array containing the elements in `values`. + */ + array(std::initializer_list<T> values) + : impl_{impl_t::from_initializer_list(values)} + {} + + /*! + * Constructs a array containing the elements in the range + * defined by the forward iterator `first` and range sentinel `last`. + */ + template <typename Iter, + typename Sent, + std::enable_if_t<detail::compatible_sentinel_v<Iter, Sent> && + detail::is_forward_iterator_v<Iter>, + bool> = true> + array(Iter first, Sent last) + : impl_{impl_t::from_range(first, last)} + {} + + /*! + * Constructs a array containing the element `val` repeated `n` + * times. + */ + array(size_type n, T v = {}) + : impl_{impl_t::from_fill(n, v)} + {} + + /*! + * Returns an iterator pointing at the first element of the + * collection. It does not allocate memory and its complexity is + * @f$ O(1) @f$. + */ + IMMER_NODISCARD iterator begin() const { return impl_.data(); } + + /*! + * Returns an iterator pointing just after the last element of the + * collection. It does not allocate and its complexity is @f$ O(1) @f$. + */ + IMMER_NODISCARD iterator end() const { return impl_.data() + impl_.size; } + + /*! + * Returns an iterator that traverses the collection backwards, + * pointing at the first element of the reversed collection. It + * does not allocate memory and its complexity is @f$ O(1) @f$. + */ + IMMER_NODISCARD reverse_iterator rbegin() const + { + return reverse_iterator{end()}; + } + + /*! + * Returns an iterator that traverses the collection backwards, + * pointing after the last element of the reversed collection. It + * does not allocate memory and its complexity is @f$ O(1) @f$. + */ + IMMER_NODISCARD reverse_iterator rend() const + { + return reverse_iterator{begin()}; + } + + /*! + * Returns the number of elements in the container. It does + * not allocate memory and its complexity is @f$ O(1) @f$. + */ + IMMER_NODISCARD std::size_t size() const { return impl_.size; } + + /*! + * Returns `true` if there are no elements in the container. It + * does not allocate memory and its complexity is @f$ O(1) @f$. + */ + IMMER_NODISCARD bool empty() const { return impl_.size == 0; } + + /*! + * Access the raw data. + */ + IMMER_NODISCARD const T* data() const { return impl_.data(); } + + /*! + * Access the last element. + */ + IMMER_NODISCARD const T& back() const { return data()[size() - 1]; } + + /*! + * Access the first element. + */ + IMMER_NODISCARD const T& front() const { return data()[0]; } + + /*! + * Returns a `const` reference to the element at position `index`. + * It is undefined when @f$ 0 index \geq size() @f$. It does not + * allocate memory and its complexity is *effectively* @f$ O(1) + * @f$. + */ + IMMER_NODISCARD reference operator[](size_type index) const + { + return impl_.get(index); + } + + /*! + * Returns a `const` reference to the element at position + * `index`. It throws an `std::out_of_range` exception when @f$ + * index \geq size() @f$. It does not allocate memory and its + * complexity is *effectively* @f$ O(1) @f$. + */ + reference at(size_type index) const { return impl_.get_check(index); } + + /*! + * Returns whether the vectors are equal. + */ + IMMER_NODISCARD bool operator==(const array& other) const + { + return impl_.equals(other.impl_); + } + IMMER_NODISCARD bool operator!=(const array& other) const + { + return !(*this == other); + } + + /*! + * Returns an array with `value` inserted at the end. It may + * allocate memory and its complexity is @f$ O(size) @f$. + * + * @rst + * + * **Example** + * .. literalinclude:: ../example/array/array.cpp + * :language: c++ + * :dedent: 8 + * :start-after: push-back/start + * :end-before: push-back/end + * + * @endrst + */ + IMMER_NODISCARD array push_back(value_type value) const& + { + return impl_.push_back(std::move(value)); + } + + IMMER_NODISCARD decltype(auto) push_back(value_type value) && + { + return push_back_move(move_t{}, std::move(value)); + } + + /*! + * Returns an array containing value `value` at position `idx`. + * Undefined for `index >= size()`. + * It may allocate memory and its complexity is @f$ O(size) @f$. + * + * @rst + * + * **Example** + * .. literalinclude:: ../example/array/array.cpp + * :language: c++ + * :dedent: 8 + * :start-after: set/start + * :end-before: set/end + * + * @endrst + */ + IMMER_NODISCARD array set(std::size_t index, value_type value) const& + { + return impl_.assoc(index, std::move(value)); + } + + IMMER_NODISCARD decltype(auto) set(size_type index, value_type value) && + { + return set_move(move_t{}, index, std::move(value)); + } + + /*! + * Returns an array containing the result of the expression + * `fn((*this)[idx])` at position `idx`. + * Undefined for `index >= size()`. + * It may allocate memory and its complexity is @f$ O(size) @f$. + * + * @rst + * + * **Example** + * .. literalinclude:: ../example/array/array.cpp + * :language: c++ + * :dedent: 8 + * :start-after: update/start + * :end-before: update/end + * + * @endrst + */ + template <typename FnT> + IMMER_NODISCARD array update(std::size_t index, FnT&& fn) const& + { + return impl_.update(index, std::forward<FnT>(fn)); + } + + template <typename FnT> + IMMER_NODISCARD decltype(auto) update(size_type index, FnT&& fn) && + { + return update_move(move_t{}, index, std::forward<FnT>(fn)); + } + + /*! + * Returns a array containing only the first `min(elems, size())` + * elements. It may allocate memory and its complexity is + * *effectively* @f$ O(1) @f$. + * + * @rst + * + * **Example** + * .. literalinclude:: ../example/array/array.cpp + * :language: c++ + * :dedent: 8 + * :start-after: take/start + * :end-before: take/end + * + * @endrst + */ + IMMER_NODISCARD array take(size_type elems) const& + { + return impl_.take(elems); + } + + IMMER_NODISCARD decltype(auto) take(size_type elems) && + { + return take_move(move_t{}, elems); + } + + /*! + * Returns an @a transient form of this container, an + * `immer::array_transient`. + */ + IMMER_NODISCARD transient_type transient() const& + { + return transient_type{impl_}; + } + IMMER_NODISCARD transient_type transient() && + { + return transient_type{std::move(impl_)}; + } + + // Semi-private + const impl_t& impl() const { return impl_; } + +private: + friend transient_type; + + array(impl_t impl) + : impl_(std::move(impl)) + {} + + array&& push_back_move(std::true_type, value_type value) + { + impl_.push_back_mut({}, std::move(value)); + return std::move(*this); + } + array push_back_move(std::false_type, value_type value) + { + return impl_.push_back(std::move(value)); + } + + array&& set_move(std::true_type, size_type index, value_type value) + { + impl_.assoc_mut({}, index, std::move(value)); + return std::move(*this); + } + array set_move(std::false_type, size_type index, value_type value) + { + return impl_.assoc(index, std::move(value)); + } + + template <typename Fn> + array&& update_move(std::true_type, size_type index, Fn&& fn) + { + impl_.update_mut({}, index, std::forward<Fn>(fn)); + return std::move(*this); + } + template <typename Fn> + array update_move(std::false_type, size_type index, Fn&& fn) + { + return impl_.update(index, std::forward<Fn>(fn)); + } + + array&& take_move(std::true_type, size_type elems) + { + impl_.take_mut({}, elems); + return std::move(*this); + } + array take_move(std::false_type, size_type elems) + { + return impl_.take(elems); + } + + impl_t impl_ = impl_t::empty(); +}; + +} /* namespace immer */ |