From Jason Turner

[range.filter.iterator]

C++17 → C++20 5.2 KB 181 lines
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Archived: C++17 | C++20
Markdown: C++17 | C++20
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  1. tmp/tmp674iwvyg/{from.md → to.md} +178 -0
tmp/tmp674iwvyg/{from.md → to.md} RENAMED
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+ #### Class `filter_view::iterator` <a id="range.filter.iterator">[[range.filter.iterator]]</a>
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+
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+ ``` cpp
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+ namespace std::ranges {
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+ template<input_range V, indirect_unary_predicate<iterator_t<V>> Pred>
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+ requires view<V> && is_object_v<Pred>
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+ class filter_view<V, Pred>::iterator {
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+ private:
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+ iterator_t<V> current_ = iterator_t<V>(); // exposition only
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+ filter_view* parent_ = nullptr; // exposition only
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+ public:
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+ using iterator_concept = see below;
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+ using iterator_category = see below;
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+ using value_type = range_value_t<V>;
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+ using difference_type = range_difference_t<V>;
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+
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+ iterator() = default;
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+ constexpr iterator(filter_view& parent, iterator_t<V> current);
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+
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+ constexpr iterator_t<V> base() const &
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+ requires copyable<iterator_t<V>>;
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+ constexpr iterator_t<V> base() &&;
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+ constexpr range_reference_t<V> operator*() const;
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+ constexpr iterator_t<V> operator->() const
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+ requires has-arrow<iterator_t<V>> && copyable<iterator_t<V>>;
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+
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+ constexpr iterator& operator++();
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+ constexpr void operator++(int);
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+ constexpr iterator operator++(int) requires forward_range<V>;
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+
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+ constexpr iterator& operator--() requires bidirectional_range<V>;
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+ constexpr iterator operator--(int) requires bidirectional_range<V>;
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+
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+ friend constexpr bool operator==(const iterator& x, const iterator& y)
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+ requires equality_comparable<iterator_t<V>>;
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+
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+ friend constexpr range_rvalue_reference_t<V> iter_move(const iterator& i)
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+ noexcept(noexcept(ranges::iter_move(i.current_)));
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+ friend constexpr void iter_swap(const iterator& x, const iterator& y)
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+ noexcept(noexcept(ranges::iter_swap(x.current_, y.current_)))
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+ requires indirectly_swappable<iterator_t<V>>;
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+ };
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+ }
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+ ```
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+
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+ Modification of the element a `filter_view::iterator` denotes is
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+ permitted, but results in undefined behavior if the resulting value does
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+ not satisfy the filter predicate.
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+
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+ `iterator::iterator_concept` is defined as follows:
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+
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+ - If `V` models `bidirectional_range`, then `iterator_concept` denotes
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+ `bidirectional_iterator_tag`.
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+ - Otherwise, if `V` models `forward_range`, then `iterator_concept`
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+ denotes `forward_iterator_tag`.
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+ - Otherwise, `iterator_concept` denotes `input_iterator_tag`.
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+
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+ `iterator::iterator_category` is defined as follows:
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+
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+ - Let `C` denote the type
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+ `iterator_traits<iterator_t<V>>::iterator_category`.
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+ - If `C` models `derived_from<bidirectional_iterator_tag>`, then
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+ `iterator_category` denotes `bidirectional_iterator_tag`.
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+ - Otherwise, if `C` models `derived_from<forward_iterator_tag>`, then
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+ `iterator_category` denotes `forward_iterator_tag`.
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+ - Otherwise, `iterator_category` denotes `C`.
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+
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+ ``` cpp
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+ constexpr iterator(filter_view& parent, iterator_t<V> current);
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+ ```
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+
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+ *Effects:* Initializes *current\_* with `std::move(current)` and
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+ *parent\_* with `addressof(parent)`.
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+
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+ ``` cpp
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+ constexpr iterator_t<V> base() const &
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+ requires copyable<iterator_t<V>>;
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+ ```
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+
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+ *Effects:* Equivalent to: `return `*`current_`*`;`
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+
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+ ``` cpp
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+ constexpr iterator_t<V> base() &&;
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+ ```
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+
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+ *Effects:* Equivalent to: `return std::move(current_);`
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+
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+ ``` cpp
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+ constexpr range_reference_t<V> operator*() const;
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+ ```
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+
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+ *Effects:* Equivalent to: `return *`*`current_`*`;`
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+
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+ ``` cpp
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+ constexpr iterator_t<V> operator->() const
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+ requires has-arrow<iterator_t<V>> && copyable<iterator_t<V>>;
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+ ```
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+
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+ *Effects:* Equivalent to: `return `*`current_`*`;`
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+
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+ ``` cpp
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+ constexpr iterator& operator++();
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ current_ = ranges::find_if(std::move(++current_), ranges::end(parent_->base_),
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+ ref(*parent_->pred_));
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+ return *this;
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+ ```
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+
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+ ``` cpp
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+ constexpr void operator++(int);
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+ ```
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+
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+ *Effects:* Equivalent to `++*this`.
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+
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+ ``` cpp
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+ constexpr iterator operator++(int) requires forward_range<V>;
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ auto tmp = *this;
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+ ++*this;
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+ return tmp;
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+ ```
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+
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+ ``` cpp
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+ constexpr iterator& operator--() requires bidirectional_range<V>;
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ do
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+ --current_;
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+ while (!invoke(*parent_->pred_, *current_));
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+ return *this;
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+ ```
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+
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+ ``` cpp
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+ constexpr iterator operator--(int) requires bidirectional_range<V>;
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+ ```
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+
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+ *Effects:* Equivalent to:
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+
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+ ``` cpp
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+ auto tmp = *this;
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+ --*this;
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+ return tmp;
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+ ```
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+
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+ ``` cpp
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+ friend constexpr bool operator==(const iterator& x, const iterator& y)
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+ requires equality_comparable<iterator_t<V>>;
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+ ```
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+
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+ *Effects:* Equivalent to: `return x.`*`current_`*` == y.`*`current_`*`;`
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+
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+ ``` cpp
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+ friend constexpr range_rvalue_reference_t<V> iter_move(const iterator& i)
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+ noexcept(noexcept(ranges::iter_move(i.current_)));
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+ ```
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+
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+ *Effects:* Equivalent to: `return ranges::iter_move(i.`*`current_`*`);`
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+
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+ ``` cpp
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+ friend constexpr void iter_swap(const iterator& x, const iterator& y)
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+ noexcept(noexcept(ranges::iter_swap(x.current_, y.current_)))
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+ requires indirectly_swappable<iterator_t<V>>;
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+ ```
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+
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+ *Effects:* Equivalent to
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+ `ranges::iter_swap(x.`*`current_`*`, y.`*`current_`*`)`.
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+