/src/immer/immer/flex_vector.hpp

Source
//
// 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/rbts/rrbtree.hpp>
#include <immer/detail/rbts/rrbtree_iterator.hpp>
#include <immer/memory_policy.hpp>

namespace immer {

template <typename T,
          typename MP,
          detail::rbts::bits_t B,
          detail::rbts::bits_t BL>
class vector;

template <typename T,
          typename MP,
          detail::rbts::bits_t B,
          detail::rbts::bits_t BL>
class flex_vector_transient;

/*!
 * Immutable sequential container supporting both random access,
 * structural sharing and efficient concatenation and slicing.
 *
 * @tparam T The type of the values to be stored in the container.
 * @tparam MemoryPolicy Memory management policy. See @ref
 *         memory_policy.
 *
 * @rst
 *
 * This container is very similar to `vector`_ but also supports
 * :math:`O(log(size))` *concatenation*, *slicing* and *insertion* at
 * any point. Its performance characteristics are almost identical
 * until one of these operations is performed.  After that,
 * performance is degraded by a constant factor that usually oscilates
 * in the range :math:`[1, 2)` depending on the operation and the
 * amount of flexible operations that have been performed.
 *
 * .. tip:: A `vector`_ can be converted to a `flex_vector`_ in
 *    constant time without any allocation.  This is so because the
 *    internal structure of a *vector* is a strict subset of the
 *    internal structure of a *flexible vector*.  You can take
 *    advantage of this property by creating normal vectors as long as
 *    the flexible operations are not needed, and convert later in
 *    your processing pipeline once and if these are needed.
 *
 * @endrst
 */
template <typename T,
          typename MemoryPolicy  = default_memory_policy,
          detail::rbts::bits_t B = default_bits,
          detail::rbts::bits_t BL =
              detail::rbts::derive_bits_leaf<T, MemoryPolicy, B>>
class flex_vector
{
    using impl_t = detail::rbts::rrbtree<T, MemoryPolicy, B, BL>;

    using move_t =
        std::integral_constant<bool, MemoryPolicy::use_transient_rvalues>;

public:
    static constexpr auto bits      = B;
    static constexpr auto bits_leaf = BL;
    using memory_policy             = MemoryPolicy;

    using value_type      = T;
    using reference       = const T&;
    using size_type       = detail::rbts::size_t;
    using difference_type = std::ptrdiff_t;
    using const_reference = const T&;

    using iterator = detail::rbts::rrbtree_iterator<T, MemoryPolicy, B, BL>;
    using const_iterator   = iterator;
    using reverse_iterator = std::reverse_iterator<iterator>;

    using transient_type = flex_vector_transient<T, MemoryPolicy, B, BL>;

    /*!
     * Returns the maximum theoretical size supported by the internal structure
     * given the current B, BL.
     */
    constexpr static size_type max_size() { return impl_t::max_size(); }

    /*!
     * Default constructor.  It creates a flex_vector of `size() == 0`.
     * It does not allocate memory and its complexity is @f$ O(1) @f$.
     */
    flex_vector() = default;

    /*!
     * Constructs a flex_vector containing the elements in `values`.
     */
    flex_vector(std::initializer_list<T> values)
        : impl_{impl_t::from_initializer_list(values)}
    {}

    /*!
     * Constructs a flex_vector containing the elements in the range
     * defined by the input iterator `first` and range sentinel `last`.
     */
    template <typename Iter,
              typename Sent,
              std::enable_if_t<detail::compatible_sentinel_v<Iter, Sent>,
                               bool> = true>
    flex_vector(Iter first, Sent last)
        : impl_{impl_t::from_range(first, last)}
    {}

    /*!
     * Constructs a vector containing the element `val` repeated `n`
     * times.
     */
    flex_vector(size_type n, T v = {})
        : impl_{impl_t::from_fill(n, v)}
    {}

    /*!
     * Default constructor.  It creates a flex_vector with the same
     * contents as `v`.  It does not allocate memory and is
     * @f$ O(1) @f$.
     */
    flex_vector(vector<T, MemoryPolicy, B, BL> v)
        : impl_{v.impl_.size,
                v.impl_.shift,
                v.impl_.root->inc(),
                v.impl_.tail->inc()}
    {}

    /*!
     * 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_}; }

    /*!
     * 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_, typename iterator::end_t{}};
    }

    /*!
     * 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 size_type 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 last element.
     */
    IMMER_NODISCARD const T& back() const { return impl_.back(); }

    /*!
     * Access the first element.
     */
    IMMER_NODISCARD const T& front() const { return impl_.front(); }

    /*!
     * 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 flex_vector& other) const
    {
        return impl_.equals(other.impl_);
    }
    IMMER_NODISCARD bool operator!=(const flex_vector& other) const
    {
        return !(*this == other);
    }

    /*!
     * Returns a flex_vector with `value` inserted at the end.  It may
     * allocate memory and its complexity is *effectively* @f$ O(1) @f$.
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: push-back/start
     *      :end-before:  push-back/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector 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 a flex_vector with `value` inserted at the front.  It may
     * allocate memory and its complexity is @f$ O(log(size)) @f$.
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: push-front/start
     *      :end-before:  push-front/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector push_front(value_type value) const
    {
        return flex_vector{}.push_back(value) + *this;
    }

    /*!
     * Returns a flex_vector containing value `value` at position `index`.
     * Undefined for `index >= size()`.
     * It may allocate memory and its complexity is
     * *effectively* @f$ O(1) @f$.
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: set/start
     *      :end-before:  set/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector set(size_type 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 a vector containing the result of the expression
     * `fn((*this)[idx])` at position `idx`.
     * Undefined for `index >= size()`.
     * It may allocate memory and its complexity is
     * *effectively* @f$ O(1) @f$.
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: update/start
     *      :end-before:  update/end
     *
     * @endrst

     */
    template <typename FnT>
    IMMER_NODISCARD flex_vector update(size_type 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 vector 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/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: take/start
     *      :end-before:  take/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector take(size_type elems) const&
    {
        return impl_.take(elems);
    }

    IMMER_NODISCARD decltype(auto) take(size_type elems) &&
    {
        return take_move(move_t{}, elems);
    }

    /*!
     * Returns a vector without the first `min(elems, size())`
     * elements. It may allocate memory and its complexity is
     * *effectively* @f$ O(1) @f$.
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: drop/start
     *      :end-before:  drop/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector drop(size_type elems) const&
    {
        return impl_.drop(elems);
    }

    IMMER_NODISCARD decltype(auto) drop(size_type elems) &&
    {
        return drop_move(move_t{}, elems);
    }

    /*!
     * Concatenation operator. Returns a flex_vector with the contents
     * of `l` followed by those of `r`.  It may allocate memory
     * and its complexity is @f$ O(log(max(size_r, size_l))) @f$
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: concat/start
     *      :end-before:  concat/end
     *
     * @endrst
     */
    IMMER_NODISCARD friend flex_vector operator+(const flex_vector& l,
                                                 const flex_vector& r)
    {
        return l.impl_.concat(r.impl_);
    }

    IMMER_NODISCARD friend decltype(auto) operator+(flex_vector&& l,
                                                    const flex_vector& r)
    {
        return concat_move(move_t{}, std::move(l), r);
    }

    IMMER_NODISCARD friend decltype(auto) operator+(const flex_vector& l,
                                                    flex_vector&& r)
    {
        return concat_move(move_t{}, l, std::move(r));
    }

    IMMER_NODISCARD friend decltype(auto) operator+(flex_vector&& l,
                                                    flex_vector&& r)
    {
        return concat_move(move_t{}, std::move(l), std::move(r));
    }

    /*!
     * Returns a flex_vector with the `value` inserted at index
     * `pos`. It may allocate memory and its complexity is @f$
     * O(log(size)) @f$
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: insert/start
     *      :end-before:  insert/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector insert(size_type pos, T value) const&
    {
        return take(pos).push_back(std::move(value)) + drop(pos);
    }
    IMMER_NODISCARD decltype(auto) insert(size_type pos, T value) &&
    {
        using std::move;
        auto rs = drop(pos);
        return std::move(*this).take(pos).push_back(std::move(value)) +
               std::move(rs);
    }

    IMMER_NODISCARD flex_vector insert(size_type pos, flex_vector value) const&
    {
        return take(pos) + std::move(value) + drop(pos);
    }
    IMMER_NODISCARD decltype(auto) insert(size_type pos, flex_vector value) &&
    {
        using std::move;
        auto rs = drop(pos);
        return std::move(*this).take(pos) + std::move(value) + std::move(rs);
    }

    /*!
     * Returns a flex_vector without the element at index `pos`. It
     * may allocate memory and its complexity is @f$ O(log(size)) @f$
     *
     * @rst
     *
     * **Example**
     *   .. literalinclude:: ../example/flex-vector/flex-vector.cpp
     *      :language: c++
     *      :dedent: 8
     *      :start-after: erase/start
     *      :end-before:  erase/end
     *
     * @endrst
     */
    IMMER_NODISCARD flex_vector erase(size_type pos) const&
    {
        return take(pos) + drop(pos + 1);
    }
    IMMER_NODISCARD decltype(auto) erase(size_type pos) &&
    {
        auto rs = drop(pos + 1);
        return std::move(*this).take(pos) + std::move(rs);
    }

    IMMER_NODISCARD flex_vector erase(size_type pos, size_type lpos) const&
    {
        return lpos > pos ? take(pos) + drop(lpos) : *this;
    }
    IMMER_NODISCARD decltype(auto) erase(size_type pos, size_type lpos) &&
    {
        if (lpos > pos) {
            auto rs = drop(lpos);
            return std::move(*this).take(pos) + std::move(rs);
        } else {
            return std::move(*this);
        }
    }

    /*!
     * Returns an @a transient form of this container, an
     * `immer::flex_vector_transient`.
     */
    IMMER_NODISCARD transient_type transient() const& { return impl_; }
    IMMER_NODISCARD transient_type transient() && { return std::move(impl_); }

    /*!
     * Returns a value that can be used as identity for the container.  If two
     * values have the same identity, they are guaranteed to be equal and to
     * contain the same objects.  However, two equal containers are not
     * guaranteed to have the same identity.
     */
    std::pair<void*, void*> identity() const
    {
        return {impl_.root, impl_.tail};
    }

    // Semi-private
    const impl_t& impl() const { return impl_; }

#if IMMER_DEBUG_PRINT
    void debug_print(std::ostream& out = std::cerr) const
    {
        impl_.debug_print(out);
    }
#endif

private:
    friend transient_type;

    flex_vector(impl_t impl)
        : impl_(std::move(impl))
    {
#if IMMER_DEBUG_PRINT
        // force the compiler to generate debug_print, so we can call
        // it from a debugger
        [](volatile auto) {}(&flex_vector::debug_print);
#endif
    }

    flex_vector&& push_back_move(std::true_type, value_type value)
    {
        impl_.push_back_mut({}, std::move(value));
        return std::move(*this);
    }
    flex_vector push_back_move(std::false_type, value_type value)
    {
        return impl_.push_back(std::move(value));
    }

    flex_vector&& set_move(std::true_type, size_type index, value_type value)
    {
        impl_.assoc_mut({}, index, std::move(value));
        return std::move(*this);
    }
    flex_vector set_move(std::false_type, size_type index, value_type value)
    {
        return impl_.assoc(index, std::move(value));
    }

    template <typename Fn>
    flex_vector&& 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>
    flex_vector update_move(std::false_type, size_type index, Fn&& fn)
    {
        return impl_.update(index, std::forward<Fn>(fn));
    }

    flex_vector&& take_move(std::true_type, size_type elems)
    {
        impl_.take_mut({}, elems);
        return std::move(*this);
    }
    flex_vector take_move(std::false_type, size_type elems)
    {
        return impl_.take(elems);
    }

    flex_vector&& drop_move(std::true_type, size_type elems)
    {
        impl_.drop_mut({}, elems);
        return std::move(*this);
    }
    flex_vector drop_move(std::false_type, size_type elems)
    {
        return impl_.drop(elems);
    }

    static flex_vector&&
    concat_move(std::true_type, flex_vector&& l, const flex_vector& r)
    {
        concat_mut_l(l.impl_, {}, r.impl_);
        return std::move(l);
    }
    static flex_vector&&
    concat_move(std::true_type, const flex_vector& l, flex_vector&& r)
    {
        concat_mut_r(l.impl_, r.impl_, {});
        return std::move(r);
    }
    static flex_vector&&
    concat_move(std::true_type, flex_vector&& l, flex_vector&& r)
    {
        concat_mut_lr_l(l.impl_, {}, r.impl_, {});
        return std::move(l);
    }
    static flex_vector
    concat_move(std::false_type, const flex_vector& l, const flex_vector& r)
    {
        return l.impl_.concat(r.impl_);
    }

    impl_t impl_ = {};
};

static_assert(std::is_nothrow_move_constructible<flex_vector<int>>::value,
              "flex_vector is not nothrow move constructible");
static_assert(std::is_nothrow_move_assignable<flex_vector<int>>::value,
              "flex_vector is not nothrow move assignable");

} // namespace immer

Coverage Report

Created: 2023-06-07 06:37

Line	Count	Source
1		//
2		// immer: immutable data structures for C++
3		// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
4		//
5		// This software is distributed under the Boost Software License, Version 1.0.
6		// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
7		//
8
9		#pragma once
10
11		#include <immer/detail/rbts/rrbtree.hpp>
12		#include <immer/detail/rbts/rrbtree_iterator.hpp>
13		#include <immer/memory_policy.hpp>
14
15		namespace immer {
16
17		template <typename T,
18		typename MP,
19		detail::rbts::bits_t B,
20		detail::rbts::bits_t BL>
21		class vector;
22
23		template <typename T,
24		typename MP,
25		detail::rbts::bits_t B,
26		detail::rbts::bits_t BL>
27		class flex_vector_transient;
28
29		/*!
30		* Immutable sequential container supporting both random access,
31		* structural sharing and efficient concatenation and slicing.
32		*
33		* @tparam T The type of the values to be stored in the container.
34		* @tparam MemoryPolicy Memory management policy. See @ref
35		* memory_policy.
36		*
37		* @rst
38		*
39		* This container is very similar to `vector`_ but also supports
40		* :math:`O(log(size))` concatenation, slicing and insertion at
41		* any point. Its performance characteristics are almost identical
42		* until one of these operations is performed. After that,
43		* performance is degraded by a constant factor that usually oscilates
44		* in the range :math:`[1, 2)` depending on the operation and the
45		* amount of flexible operations that have been performed.
46		*
47		* .. tip:: A `vector`_ can be converted to a `flex_vector`_ in
48		* constant time without any allocation. This is so because the
49		* internal structure of a vector is a strict subset of the
50		* internal structure of a flexible vector. You can take
51		* advantage of this property by creating normal vectors as long as
52		* the flexible operations are not needed, and convert later in
53		* your processing pipeline once and if these are needed.
54		*
55		* @endrst
56		*/
57		template <typename T,
58		typename MemoryPolicy = default_memory_policy,
59		detail::rbts::bits_t B = default_bits,
60		detail::rbts::bits_t BL =
61		detail::rbts::derive_bits_leaf<T, MemoryPolicy, B>>
62		class flex_vector
63		{
64		using impl_t = detail::rbts::rrbtree<T, MemoryPolicy, B, BL>;
65
66		using move_t =
67		std::integral_constant<bool, MemoryPolicy::use_transient_rvalues>;
68
69		public:
70		static constexpr auto bits = B;
71		static constexpr auto bits_leaf = BL;
72		using memory_policy = MemoryPolicy;
73
74		using value_type = T;
75		using reference = const T&;
76		using size_type = detail::rbts::size_t;
77		using difference_type = std::ptrdiff_t;
78		using const_reference = const T&;
79
80		using iterator = detail::rbts::rrbtree_iterator<T, MemoryPolicy, B, BL>;
81		using const_iterator = iterator;
82		using reverse_iterator = std::reverse_iterator<iterator>;
83
84		using transient_type = flex_vector_transient<T, MemoryPolicy, B, BL>;
85
86		/*!
87		* Returns the maximum theoretical size supported by the internal structure
88		* given the current B, BL.
89		*/
90	1.67M	constexpr static size_type max_size() { return impl_t::max_size(); }
91
92		/*!
93		* Default constructor. It creates a flex_vector of `size() == 0`.
94		* It does not allocate memory and its complexity is @f$ O(1) @f$.
95		*/
96	80.7k	flex_vector() = default;
97
98		/*!
99		* Constructs a flex_vector containing the elements in `values`.
100		*/
101		flex_vector(std::initializer_list<T> values)
102		: impl_{impl_t::from_initializer_list(values)}
103		{}
104
105		/*!
106		* Constructs a flex_vector containing the elements in the range
107		* defined by the input iterator `first` and range sentinel `last`.
108		*/
109		template <typename Iter,
110		typename Sent,
111		std::enable_if_t<detail::compatible_sentinel_v<Iter, Sent>,
112		bool> = true>
113		flex_vector(Iter first, Sent last)
114		: impl_{impl_t::from_range(first, last)}
115		{}
116
117		/*!
118		* Constructs a vector containing the element `val` repeated `n`
119		* times.
120		*/
121		flex_vector(size_type n, T v = {})
122		: impl_{impl_t::from_fill(n, v)}
123		{}
124
125		/*!
126		* Default constructor. It creates a flex_vector with the same
127		* contents as `v`. It does not allocate memory and is
128		* @f$ O(1) @f$.
129		*/
130		flex_vector(vector<T, MemoryPolicy, B, BL> v)
131		: impl_{v.impl_.size,
132		v.impl_.shift,
133		v.impl_.root->inc(),
134		v.impl_.tail->inc()}
135		{}
136
137		/*!
138		* Returns an iterator pointing at the first element of the
139		* collection. It does not allocate memory and its complexity is
140		* @f$ O(1) @f$.
141		*/
142		IMMER_NODISCARD iterator begin() const { return {impl_}; }
143
144		/*!
145		* Returns an iterator pointing just after the last element of the
146		* collection. It does not allocate and its complexity is @f$ O(1) @f$.
147		*/
148		IMMER_NODISCARD iterator end() const
149		{
150		return {impl_, typename iterator::end_t{}};
151		}
152
153		/*!
154		* Returns an iterator that traverses the collection backwards,
155		* pointing at the first element of the reversed collection. It
156		* does not allocate memory and its complexity is @f$ O(1) @f$.
157		*/
158		IMMER_NODISCARD reverse_iterator rbegin() const
159		{
160		return reverse_iterator{end()};
161		}
162
163		/*!
164		* Returns an iterator that traverses the collection backwards,
165		* pointing after the last element of the reversed collection. It
166		* does not allocate memory and its complexity is @f$ O(1) @f$.
167		*/
168		IMMER_NODISCARD reverse_iterator rend() const
169		{
170		return reverse_iterator{begin()};
171		}
172
173		/*!
174		* Returns the number of elements in the container. It does
175		* not allocate memory and its complexity is @f$ O(1) @f$.
176		*/
177	3.91M	IMMER_NODISCARD size_type size() const { return impl_.size; }
178
179		/*!
180		* Returns `true` if there are no elements in the container. It
181		* does not allocate memory and its complexity is @f$ O(1) @f$.
182		*/
183		IMMER_NODISCARD bool empty() const { return impl_.size == 0; }
184
185		/*!
186		* Access the last element.
187		*/
188		IMMER_NODISCARD const T& back() const { return impl_.back(); }
189
190		/*!
191		* Access the first element.
192		*/
193		IMMER_NODISCARD const T& front() const { return impl_.front(); }
194
195		/*!
196		* Returns a `const` reference to the element at position `index`.
197		* It is undefined when @f$ 0 index \geq size() @f$. It does not
198		* allocate memory and its complexity is effectively @f$ O(1)
199		* @f$.
200		*/
201		IMMER_NODISCARD reference operator[](size_type index) const
202		{
203		return impl_.get(index);
204		}
205
206		/*!
207		* Returns a `const` reference to the element at position
208		* `index`. It throws an `std::out_of_range` exception when @f$
209		* index \geq size() @f$. It does not allocate memory and its
210		* complexity is effectively @f$ O(1) @f$.
211		*/
212		reference at(size_type index) const { return impl_.get_check(index); }
213
214		/*!
215		* Returns whether the vectors are equal.
216		*/
217		IMMER_NODISCARD bool operator==(const flex_vector& other) const
218	27.0k	{
219	27.0k	return impl_.equals(other.impl_);
220	27.0k	}
221		IMMER_NODISCARD bool operator!=(const flex_vector& other) const
222		{
223		return !(*this == other);
224		}
225
226		/*!
227		* Returns a flex_vector with `value` inserted at the end. It may
228		* allocate memory and its complexity is effectively @f$ O(1) @f$.
229		*
230		* @rst
231		*
232		* Example
233		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
234		* :language: c++
235		* :dedent: 8
236		* :start-after: push-back/start
237		* :end-before: push-back/end
238		*
239		* @endrst
240		*/
241		IMMER_NODISCARD flex_vector push_back(value_type value) const&
242	261k	{
243	261k	return impl_.push_back(std::move(value));
244	261k	}
245
246		IMMER_NODISCARD decltype(auto) push_back(value_type value) &&
247	34.0k	{
248	34.0k	return push_back_move(move_t{}, std::move(value));
249	34.0k	}
250
251		/*!
252		* Returns a flex_vector with `value` inserted at the front. It may
253		* allocate memory and its complexity is @f$ O(log(size)) @f$.
254		*
255		* @rst
256		*
257		* Example
258		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
259		* :language: c++
260		* :dedent: 8
261		* :start-after: push-front/start
262		* :end-before: push-front/end
263		*
264		* @endrst
265		*/
266		IMMER_NODISCARD flex_vector push_front(value_type value) const
267		{
268		return flex_vector{}.push_back(value) + *this;
269		}
270
271		/*!
272		* Returns a flex_vector containing value `value` at position `index`.
273		* Undefined for `index >= size()`.
274		* It may allocate memory and its complexity is
275		* effectively @f$ O(1) @f$.
276		*
277		* @rst
278		*
279		* Example
280		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
281		* :language: c++
282		* :dedent: 8
283		* :start-after: set/start
284		* :end-before: set/end
285		*
286		* @endrst
287		*/
288		IMMER_NODISCARD flex_vector set(size_type index, value_type value) const&
289		{
290		return impl_.assoc(index, std::move(value));
291		}
292
293		IMMER_NODISCARD decltype(auto) set(size_type index, value_type value) &&
294		{
295		return set_move(move_t{}, index, std::move(value));
296		}
297
298		/*!
299		* Returns a vector containing the result of the expression
300		* `fn((*this)[idx])` at position `idx`.
301		* Undefined for `index >= size()`.
302		* It may allocate memory and its complexity is
303		* effectively @f$ O(1) @f$.
304		*
305		* @rst
306		*
307		* Example
308		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
309		* :language: c++
310		* :dedent: 8
311		* :start-after: update/start
312		* :end-before: update/end
313		*
314		* @endrst
315
316		*/
317		template <typename FnT>
318		IMMER_NODISCARD flex_vector update(size_type index, FnT&& fn) const&
319	273k	{
320	273k	return impl_.update(index, std::forward<FnT>(fn));
321	273k	}
322
323		template <typename FnT>
324		IMMER_NODISCARD decltype(auto) update(size_type index, FnT&& fn) &&
325	65.4k	{
326	65.4k	return update_move(move_t{}, index, std::forward<FnT>(fn));
327	65.4k	}
328
329		/*!
330		* Returns a vector containing only the first `min(elems, size())`
331		* elements. It may allocate memory and its complexity is
332		* effectively @f$ O(1) @f$.
333		*
334		* @rst
335		*
336		* Example
337		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
338		* :language: c++
339		* :dedent: 8
340		* :start-after: take/start
341		* :end-before: take/end
342		*
343		* @endrst
344		*/
345		IMMER_NODISCARD flex_vector take(size_type elems) const&
346	27.5k	{
347	27.5k	return impl_.take(elems);
348	27.5k	}
349
350		IMMER_NODISCARD decltype(auto) take(size_type elems) &&
351	43.6k	{
352	43.6k	return take_move(move_t{}, elems);
353	43.6k	}
354
355		/*!
356		* Returns a vector without the first `min(elems, size())`
357		* elements. It may allocate memory and its complexity is
358		* effectively @f$ O(1) @f$.
359		*
360		* @rst
361		*
362		* Example
363		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
364		* :language: c++
365		* :dedent: 8
366		* :start-after: drop/start
367		* :end-before: drop/end
368		*
369		* @endrst
370		*/
371		IMMER_NODISCARD flex_vector drop(size_type elems) const&
372	29.6k	{
373	29.6k	return impl_.drop(elems);
374	29.6k	}
375
376		IMMER_NODISCARD decltype(auto) drop(size_type elems) &&
377	43.6k	{
378	43.6k	return drop_move(move_t{}, elems);
379	43.6k	}
380
381		/*!
382		* Concatenation operator. Returns a flex_vector with the contents
383		* of `l` followed by those of `r`. It may allocate memory
384		* and its complexity is @f$ O(log(max(size_r, size_l))) @f$
385		*
386		* @rst
387		*
388		* Example
389		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
390		* :language: c++
391		* :dedent: 8
392		* :start-after: concat/start
393		* :end-before: concat/end
394		*
395		* @endrst
396		*/
397		IMMER_NODISCARD friend flex_vector operator+(const flex_vector& l,
398		const flex_vector& r)
399	990k	{
400	990k	return l.impl_.concat(r.impl_);
401	990k	}
402
403		IMMER_NODISCARD friend decltype(auto) operator+(flex_vector&& l,
404		const flex_vector& r)
405	557k	{
406	557k	return concat_move(move_t{}, std::move(l), r);
407	557k	}
408
409		IMMER_NODISCARD friend decltype(auto) operator+(const flex_vector& l,
410		flex_vector&& r)
411	4.19k	{
412	4.19k	return concat_move(move_t{}, l, std::move(r));
413	4.19k	}
414
415		IMMER_NODISCARD friend decltype(auto) operator+(flex_vector&& l,
416		flex_vector&& r)
417	27.5k	{
418	27.5k	return concat_move(move_t{}, std::move(l), std::move(r));
419	27.5k	}
420
421		/*!
422		* Returns a flex_vector with the `value` inserted at index
423		* `pos`. It may allocate memory and its complexity is @f$
424		* O(log(size)) @f$
425		*
426		* @rst
427		*
428		* Example
429		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
430		* :language: c++
431		* :dedent: 8
432		* :start-after: insert/start
433		* :end-before: insert/end
434		*
435		* @endrst
436		*/
437		IMMER_NODISCARD flex_vector insert(size_type pos, T value) const&
438	22.0k	{
439	22.0k	return take(pos).push_back(std::move(value)) + drop(pos);
440	22.0k	}
441		IMMER_NODISCARD decltype(auto) insert(size_type pos, T value) &&
442		{
443		using std::move;
444		auto rs = drop(pos);
445		return std::move(*this).take(pos).push_back(std::move(value)) +
446		std::move(rs);
447		}
448
449		IMMER_NODISCARD flex_vector insert(size_type pos, flex_vector value) const&
450		{
451		return take(pos) + std::move(value) + drop(pos);
452		}
453		IMMER_NODISCARD decltype(auto) insert(size_type pos, flex_vector value) &&
454		{
455		using std::move;
456		auto rs = drop(pos);
457		return std::move(*this).take(pos) + std::move(value) + std::move(rs);
458		}
459
460		/*!
461		* Returns a flex_vector without the element at index `pos`. It
462		* may allocate memory and its complexity is @f$ O(log(size)) @f$
463		*
464		* @rst
465		*
466		* Example
467		* .. literalinclude:: ../example/flex-vector/flex-vector.cpp
468		* :language: c++
469		* :dedent: 8
470		* :start-after: erase/start
471		* :end-before: erase/end
472		*
473		* @endrst
474		*/
475		IMMER_NODISCARD flex_vector erase(size_type pos) const&
476	3.36k	{
477	3.36k	return take(pos) + drop(pos + 1);
478	3.36k	}
479		IMMER_NODISCARD decltype(auto) erase(size_type pos) &&
480		{
481		auto rs = drop(pos + 1);
482		return std::move(*this).take(pos) + std::move(rs);
483		}
484
485		IMMER_NODISCARD flex_vector erase(size_type pos, size_type lpos) const&
486		{
487		return lpos > pos ? take(pos) + drop(lpos) : *this;
488		}
489		IMMER_NODISCARD decltype(auto) erase(size_type pos, size_type lpos) &&
490		{
491		if (lpos > pos) {
492		auto rs = drop(lpos);
493		return std::move(*this).take(pos) + std::move(rs);
494		} else {
495		return std::move(*this);
496		}
497		}
498
499		/*!
500		* Returns an @a transient form of this container, an
501		* `immer::flex_vector_transient`.
502		*/
503		IMMER_NODISCARD transient_type transient() const& { return impl_; }
504		IMMER_NODISCARD transient_type transient() && { return std::move(impl_); }
505
506		/*!
507		* Returns a value that can be used as identity for the container. If two
508		* values have the same identity, they are guaranteed to be equal and to
509		* contain the same objects. However, two equal containers are not
510		* guaranteed to have the same identity.
511		*/
512		std::pair<void, void> identity() const
513		{
514		return {impl_.root, impl_.tail};
515		}
516
517		// Semi-private
518		const impl_t& impl() const { return impl_; }
519
520		#if IMMER_DEBUG_PRINT
521		void debug_print(std::ostream& out = std::cerr) const
522		{
523		impl_.debug_print(out);
524		}
525		#endif
526
527		private:
528		friend transient_type;
529
530		flex_vector(impl_t impl)
531		: impl_(std::move(impl))
532	1.58M	{
533		#if IMMER_DEBUG_PRINT
534		// force the compiler to generate debug_print, so we can call
535		// it from a debugger
536		[](volatile auto) {}(&flex_vector::debug_print);
537		#endif
538	1.58M	}
539
540		flex_vector&& push_back_move(std::true_type, value_type value)
541	34.0k	{
542	34.0k	impl_.push_back_mut({}, std::move(value));
543	34.0k	return std::move(*this);
544	34.0k	}
545		flex_vector push_back_move(std::false_type, value_type value)
546		{
547		return impl_.push_back(std::move(value));
548		}
549
550		flex_vector&& set_move(std::true_type, size_type index, value_type value)
551		{
552		impl_.assoc_mut({}, index, std::move(value));
553		return std::move(*this);
554		}
555		flex_vector set_move(std::false_type, size_type index, value_type value)
556		{
557		return impl_.assoc(index, std::move(value));
558		}
559
560		template <typename Fn>
561		flex_vector&& update_move(std::true_type, size_type index, Fn&& fn)
562	65.4k	{
563	65.4k	impl_.update_mut({}, index, std::forward<Fn>(fn));
564	65.4k	return std::move(*this);
565	65.4k	}
566		template <typename Fn>
567		flex_vector update_move(std::false_type, size_type index, Fn&& fn)
568		{
569		return impl_.update(index, std::forward<Fn>(fn));
570		}
571
572		flex_vector&& take_move(std::true_type, size_type elems)
573	43.6k	{
574	43.6k	impl_.take_mut({}, elems);
575	43.6k	return std::move(*this);
576	43.6k	}
577		flex_vector take_move(std::false_type, size_type elems)
578		{
579		return impl_.take(elems);
580		}
581
582		flex_vector&& drop_move(std::true_type, size_type elems)
583	43.6k	{
584	43.6k	impl_.drop_mut({}, elems);
585	43.6k	return std::move(*this);
586	43.6k	}
587		flex_vector drop_move(std::false_type, size_type elems)
588		{
589		return impl_.drop(elems);
590		}
591
592		static flex_vector&&
593		concat_move(std::true_type, flex_vector&& l, const flex_vector& r)
594	557k	{
595	557k	concat_mut_l(l.impl_, {}, r.impl_);
596	557k	return std::move(l);
597	557k	}
598		static flex_vector&&
599		concat_move(std::true_type, const flex_vector& l, flex_vector&& r)
600	4.19k	{
601	4.19k	concat_mut_r(l.impl_, r.impl_, {});
602	4.19k	return std::move(r);
603	4.19k	}
604		static flex_vector&&
605		concat_move(std::true_type, flex_vector&& l, flex_vector&& r)
606	27.5k	{
607	27.5k	concat_mut_lr_l(l.impl_, {}, r.impl_, {});
608	27.5k	return std::move(l);
609	27.5k	}
610		static flex_vector
611		concat_move(std::false_type, const flex_vector& l, const flex_vector& r)
612		{
613		return l.impl_.concat(r.impl_);
614		}
615
616		impl_t impl_ = {};
617		};
618
619		static_assert(std::is_nothrow_move_constructible<flex_vector<int>>::value,
620		"flex_vector is not nothrow move constructible");
621		static_assert(std::is_nothrow_move_assignable<flex_vector<int>>::value,
622		"flex_vector is not nothrow move assignable");
623
624		} // namespace immer