264 lines
16 KiB
Markdown
264 lines
16 KiB
Markdown
[range.join.iterator]
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# 25 Ranges library [[ranges]](./#ranges)
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## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.join.iterator)
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### 25.7.14 Join view [[range.join]](range.join#iterator)
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#### 25.7.14.3 Class template join_view::*iterator* [range.join.iterator]
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[ð](#lib:join_view::iterator)
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namespace std::ranges {template<[input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]") V>requires [view](range.view#concept:view "25.4.5 Views [range.view]")<V> && [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<V>>template<bool Const>struct join_view<V>::*iterator* {private:using *Parent* = *maybe-const*<Const, join_view>; // *exposition only*using *Base* = *maybe-const*<Const, V>; // *exposition only*using *OuterIter* = iterator_t<*Base*>; // *exposition only*using *InnerIter* = iterator_t<range_reference_t<*Base*>>; // *exposition only*static constexpr bool *ref-is-glvalue* = // *exposition only* is_reference_v<range_reference_t<*Base*>>; *OuterIter* *outer_* = *OuterIter*(); // *exposition only*, present only// if *Base* models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]") optional<*InnerIter*> *inner_*; // *exposition only**Parent** *parent_* = nullptr; // *exposition only*constexpr void *satisfy*(); // *exposition only*constexpr *OuterIter*& *outer*(); // *exposition only*constexpr const *OuterIter*& *outer*() const; // *exposition only*constexpr *iterator*(*Parent*& parent, *OuterIter* outer)requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; // *exposition only*constexpr explicit *iterator*(*Parent*& parent)requires (<*Base*>); // *exposition only*public:using iterator_concept = *see below*; using iterator_category = *see below*; // not always presentusing value_type = range_value_t<range_reference_t<*Base*>>; using difference_type = *see below*; *iterator*() = default; constexpr *iterator*(*iterator*<!Const> i)requires Const &&[convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_to [concept.convertible]")<iterator_t<V>, *OuterIter*> &&[convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_to [concept.convertible]")<iterator_t<*InnerRng*>, *InnerIter*>; constexpr decltype(auto) operator*() const { return ***inner_*; }constexpr *InnerIter* operator->() constrequires [*has-arrow*](range.utility.helpers#concept:has-arrow "25.5.2 Helper concepts [range.utility.helpers]")<*InnerIter*> && [copyable](concepts.object#concept:copyable "18.6 Object concepts [concepts.object]")<*InnerIter*>; constexpr *iterator*& operator++(); constexpr void operator++(int); constexpr *iterator* operator++(int)requires *ref-is-glvalue* && [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<*Base*> &&[forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<*Base*>>; constexpr *iterator*& operator--()requires *ref-is-glvalue* && [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<*Base*> &&[bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<*Base*>> &&[common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<*Base*>>; constexpr *iterator* operator--(int)requires *ref-is-glvalue* && [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<*Base*> &&[bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<*Base*>> &&[common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<*Base*>>; friend constexpr bool operator==(const *iterator*& x, const *iterator*& y)requires *ref-is-glvalue* && [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<*Base*> &&[equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_comparable [concept.equalitycomparable]")<iterator_t<range_reference_t<*Base*>>>; friend constexpr decltype(auto) iter_move(const *iterator*& i)noexcept(noexcept(ranges::iter_move(*i.*inner_*))) {return ranges::iter_move(*i.*inner_*); }friend constexpr void iter_swap(const *iterator*& x, const *iterator*& y)noexcept(noexcept(ranges::iter_swap(*x.*inner_*, *y.*inner_*)))requires [indirectly_swappable](alg.req.ind.swap#concept:indirectly_swappable "24.3.7.4 Concept indirectly_swappable [alg.req.ind.swap]")<*InnerIter*>; };}
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6843)
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*iterator*::iterator_concept is defined as follows:
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- [(1.1)](#1.1)
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If *ref-is-glvalue* is true, *Base* models [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]"), and range_reference_t<*Base*> models
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both [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]") and [common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]"),
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then iterator_concept denotes bidirectional_iterator_tag[.](#1.1.sentence-1)
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- [(1.2)](#1.2)
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Otherwise, if *ref-is-glvalue* is true and *Base* and range_reference_t<*Base*> each model [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]"), then iterator_concept denotes forward_iterator_tag[.](#1.2.sentence-1)
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- [(1.3)](#1.3)
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Otherwise, iterator_concept denotes input_iterator_tag[.](#1.3.sentence-1)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6858)
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The member [*typedef-name*](dcl.typedef#nt:typedef-name "9.2.4 The typedef specifier [dcl.typedef]") iterator_category is defined
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if and only if *ref-is-glvalue* is true,*Base* models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]"), andrange_reference_t<*Base*> models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")[.](#2.sentence-1)
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In that case,*iterator*::iterator_category is defined as follows:
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- [(2.1)](#2.1)
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Let *OUTERC* denote iterator_traits<iterator_t<*Base*>>::iterator_category, and
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let *INNERC* denote iterator_traits<iterator_t<range_reference_t<*Base*>>>::iterator_category[.](#2.1.sentence-1)
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- [(2.2)](#2.2)
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If *OUTERC* and *INNERC* each model [derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_from [concept.derived]")<bidirectional_iterator_tag> and range_reference_t<*Base*> models [common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]"), iterator_category denotes bidirectional_iterator_tag[.](#2.2.sentence-1)
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- [(2.3)](#2.3)
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Otherwise, if *OUTERC* and *INNERC* each model [derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_from [concept.derived]")<forward_iterator_tag>, iterator_category denotes forward_iterator_tag[.](#2.3.sentence-1)
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- [(2.4)](#2.4)
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Otherwise, iterator_category denotes input_iterator_tag[.](#2.4.sentence-1)
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6883)
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*iterator*::difference_type denotes the type:common_type_t< range_difference_t<*Base*>,
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range_difference_t<range_reference_t<*Base*>>>
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6891)
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join_view iterators use the *satisfy* function to skip over
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empty inner ranges[.](#4.sentence-1)
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[ð](#lib:outer,join_view::iterator)
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`constexpr OuterIter& outer();
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constexpr const OuterIter& outer() const;
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`
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[5](#5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6902)
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*Returns*: *outer_* if *Base* models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]");
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otherwise, **parent_*->*outer_*[.](#5.sentence-1)
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[ð](#lib:satisfy,join_view::iterator)
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`constexpr void satisfy();
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`
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[6](#6)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6914)
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*Effects*: Equivalent to:auto update_inner = [this](const iterator_t<*Base*>& x) -> auto&& {if constexpr (*ref-is-glvalue*) // *x is a referencereturn *x; elsereturn *parent_*->*inner_*.*emplace-deref*(x);};
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for (; *outer*() != ranges::end(*parent_*->*base_*); ++*outer*()) {auto&& inner = update_inner(*outer*()); *inner_* = ranges::begin(inner); if (**inner_* != ranges::end(inner))return;}if constexpr (*ref-is-glvalue*)*inner_*.reset();
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[ð](#lib:join_view::iterator,constructor)
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`constexpr iterator(Parent& parent, OuterIter outer)
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requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<Base>;
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`
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[7](#7)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6943)
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*Effects*: Initializes *outer_* with std::move(outer) and*parent_* with addressof(parent); then calls *satisfy*()[.](#7.sentence-1)
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[ð](#lib:join_view::iterator,constructor_)
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`constexpr explicit iterator(Parent& parent)
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requires (<Base>);
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`
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[8](#8)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6956)
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*Effects*: Initializes *parent_* with addressof(parent);
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then calls *satisfy*()[.](#8.sentence-1)
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[ð](#lib:join_view::iterator,constructor__)
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`constexpr iterator(iterator<!Const> i)
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requires Const &&
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[convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_to [concept.convertible]")<iterator_t<V>, OuterIter> &&
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[convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_to [concept.convertible]")<iterator_t<InnerRng>, InnerIter>;
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`
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[9](#9)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6971)
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*Effects*: Initializes *outer_* with std::move(i.*outer_*),*inner_* with std::move(i.*inner_*), and*parent_* with i.*parent_*[.](#9.sentence-1)
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[10](#10)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6977)
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[*Note [1](#note-1)*:
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Const can only be true when *Base* models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")[.](#10.sentence-1)
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â *end note*]
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[ð](#lib:operator-%3e,join_view::iterator)
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`constexpr InnerIter operator->() const
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requires [has-arrow](range.utility.helpers#concept:has-arrow "25.5.2 Helper concepts [range.utility.helpers]")<InnerIter> && [copyable](concepts.object#concept:copyable "18.6 Object concepts [concepts.object]")<InnerIter>;
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`
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[11](#11)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L6991)
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*Effects*: Equivalent to: return **inner_*;
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[ð](#lib:operator++,join_view::iterator)
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`constexpr iterator& operator++();
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`
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[12](#12)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7002)
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Let *inner-range* be:
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- [(12.1)](#12.1)
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If *ref-is-glvalue* is true, **outer*()[.](#12.1.sentence-1)
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- [(12.2)](#12.2)
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Otherwise, **parent_*->*inner_*[.](#12.2.sentence-1)
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[13](#13)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7009)
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*Effects*: Equivalent to:if (++**inner_* == ranges::end(*as-lvalue*(*inner-range*))) {++*outer*(); *satisfy*();}return *this;
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[ð](#lib:operator++,join_view::iterator_)
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`constexpr void operator++(int);
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`
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[14](#14)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7027)
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*Effects*: Equivalent to: ++*this[.](#14.sentence-1)
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[ð](#lib:operator++,join_view::iterator__)
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`constexpr iterator operator++(int)
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requires ref-is-glvalue && [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<Base> &&
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[forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<Base>>;
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`
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[15](#15)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7040)
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*Effects*: Equivalent to:auto tmp = *this;++*this;return tmp;
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[ð](#lib:operator--,join_view::iterator)
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`constexpr iterator& operator--()
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requires ref-is-glvalue && [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base> &&
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[bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<Base>> &&
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[common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<Base>>;
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`
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[16](#16)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7059)
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*Effects*: Equivalent to:if (*outer_* == ranges::end(*parent_*->*base_*))*inner_* = ranges::end(*as-lvalue*(*--*outer_*));while (**inner_* == ranges::begin(*as-lvalue*(**outer_*)))**inner_* = ranges::end(*as-lvalue*(*--*outer_*));--**inner_*;return *this;
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[ð](#lib:operator--,join_view::iterator_)
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`constexpr iterator operator--(int)
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requires ref-is-glvalue && [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base> &&
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[bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<Base>> &&
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[common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<range_reference_t<Base>>;
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`
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[17](#17)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7081)
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*Effects*: Equivalent to:auto tmp = *this;--*this;return tmp;
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[ð](#lib:operator==,join_view::iterator)
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`friend constexpr bool operator==(const iterator& x, const iterator& y)
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requires ref-is-glvalue && [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<Base> &&
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[equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_comparable [concept.equalitycomparable]")<iterator_t<range_reference_t<Base>>>;
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`
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[18](#18)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7099)
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*Effects*: Equivalent to:return x.*outer_* == y.*outer_* && x.*inner_* == y.*inner_*;
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[ð](#lib:iter_swap,join_view::iterator)
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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.inner_, *y.inner_)))
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requires [indirectly_swappable](alg.req.ind.swap#concept:indirectly_swappable "24.3.7.4 Concept indirectly_swappable [alg.req.ind.swap]")<InnerIter>;
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`
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[19](#19)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L7113)
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*Effects*: Equivalent to: ranges::iter_swap(*x.*inner_*, *y.*inner_*);
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