64 lines
2.2 KiB
Markdown
64 lines
2.2 KiB
Markdown
[intseq]
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# 21 Metaprogramming library [[meta]](./#meta)
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## 21.2 Compile-time integer sequences [intseq]
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### [21.2.1](#general) General [[intseq.general]](intseq.general)
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[1](#general-1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/meta.tex#L21)
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The library provides a class template that can represent an integer sequence[.](#general-1.sentence-1)
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When used as an argument to a function template the template parameter pack defining the
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sequence can be deduced and used in a pack expansion[.](#general-1.sentence-2)
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[*Note [1](#general-note-1)*:
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The index_sequence alias template is provided for the common case of
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an integer sequence of type size_t; see also [[tuple.apply]](tuple.apply "22.4.6 Calling a function with a tuple of arguments")[.](#general-1.sentence-3)
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â *end note*]
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### [21.2.2](#intseq) Class template integer_sequence [[intseq.intseq]](intseq.intseq)
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[ð](#lib:integer_sequence)
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namespace std {template<class T, T... I> struct integer_sequence {using value_type = T; static constexpr size_t size() noexcept { return sizeof...(I); }};}
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[1](#intseq-1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/meta.tex#L43)
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*Mandates*: T is an integer type[.](#intseq-1.sentence-1)
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### [21.2.3](#make) Alias template make_integer_sequence [[intseq.make]](intseq.make)
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[ð](#lib:make_integer_sequence)
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`template<class T, T N>
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using make_integer_sequence = integer_sequence<T, see below>;
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`
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[1](#make-1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/meta.tex#L56)
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*Mandates*: N ⥠0[.](#make-1.sentence-1)
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[2](#make-2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/meta.tex#L60)
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The alias templatemake_integer_sequence denotes a specialization ofinteger_sequence with N constant template arguments[.](#make-2.sentence-1)
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The type make_integer_sequence<T, N> is an alias for the typeinteger_sequence<T, 0, 1, …, N - 1>[.](#make-2.sentence-2)
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[*Note [1](#make-note-1)*:
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make_integer_sequence<int, 0> is an alias for the typeinteger_sequence<int>[.](#make-2.sentence-3)
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â *end note*]
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