142 lines
5.0 KiB
Markdown
142 lines
5.0 KiB
Markdown
[transform.inclusive.scan]
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# 26 Algorithms library [[algorithms]](./#algorithms)
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## 26.10 Generalized numeric operations [[numeric.ops]](numeric.ops#transform.inclusive.scan)
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### 26.10.11 Transform inclusive scan [transform.inclusive.scan]
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[ð](#lib:transform_inclusive_scan)
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`template<class InputIterator, class OutputIterator,
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class BinaryOperation, class UnaryOperation>
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constexpr OutputIterator
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transform_inclusive_scan(InputIterator first, InputIterator last,
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OutputIterator result,
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BinaryOperation binary_op, UnaryOperation unary_op);
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template<class ExecutionPolicy,
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class ForwardIterator1, class ForwardIterator2,
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class BinaryOperation, class UnaryOperation>
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ForwardIterator2
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transform_inclusive_scan(ExecutionPolicy&& exec,
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ForwardIterator1 first, ForwardIterator1 last,
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ForwardIterator2 result,
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BinaryOperation binary_op, UnaryOperation unary_op);
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template<class InputIterator, class OutputIterator,
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class BinaryOperation, class UnaryOperation, class T>
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constexpr OutputIterator
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transform_inclusive_scan(InputIterator first, InputIterator last,
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OutputIterator result,
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BinaryOperation binary_op, UnaryOperation unary_op,
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T init);
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template<class ExecutionPolicy,
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class ForwardIterator1, class ForwardIterator2,
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class BinaryOperation, class UnaryOperation, class T>
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ForwardIterator2
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transform_inclusive_scan(ExecutionPolicy&& exec,
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ForwardIterator1 first, ForwardIterator1 last,
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ForwardIterator2 result,
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BinaryOperation binary_op, UnaryOperation unary_op,
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T init);
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`
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13046)
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Let U be the value type of decltype(first)[.](#1.sentence-1)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13049)
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*Mandates*: If init is provided, all of
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- [(2.1)](#2.1)
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binary_op(init, init),
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- [(2.2)](#2.2)
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binary_op(init, unary_op(*first)), and
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- [(2.3)](#2.3)
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binary_op(unary_op(*first), unary_op(*first))
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are convertible to T;
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otherwise, binary_op(unary_op(*first), unary_op(*first)) is convertible to U[.](#2.sentence-1)
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[3](#3)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13061)
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*Preconditions*:
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- [(3.1)](#3.1)
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If init is provided, T meets the [*Cpp17MoveConstructible*](utility.arg.requirements#:Cpp17MoveConstructible "16.4.4.2 Template argument requirements [utility.arg.requirements]") (Table [31](utility.arg.requirements#tab:cpp17.moveconstructible "Table 31: Cpp17MoveConstructible requirements")) requirements;
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otherwise, U meets the [*Cpp17MoveConstructible*](utility.arg.requirements#:Cpp17MoveConstructible "16.4.4.2 Template argument requirements [utility.arg.requirements]") requirements[.](#3.1.sentence-1)
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- [(3.2)](#3.2)
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Neither unary_op nor binary_op invalidates
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iterators or subranges, nor modifies elements in
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the ranges [first, last] or [result, result + (last - first)][.](#3.2.sentence-1)
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[4](#4)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13075)
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*Effects*: For each integer K in [0, last - first)
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assigns through result + K the value of
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- [(4.1)](#4.1)
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*GENERALIZED_NONCOMMUTATIVE_SUM*(
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binary_op, init,
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unary_op(*(first + 0)), unary_op(*(first + 1)), …, unary_op(*(first + K)))
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if init is provided, or
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- [(4.2)](#4.2)
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*GENERALIZED_NONCOMMUTATIVE_SUM*(
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binary_op,
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unary_op(*(first + 0)), unary_op(*(first + 1)), …, unary_op(*(first + K)))
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otherwise[.](#4.2.sentence-2)
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[5](#5)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13088)
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*Returns*: The end of the resulting range beginning at result[.](#5.sentence-1)
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[6](#6)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13092)
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*Complexity*: O(last - first) applications each
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of unary_op and binary_op[.](#6.sentence-1)
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[7](#7)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13097)
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*Remarks*: result may be equal to first[.](#7.sentence-1)
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[8](#8)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/algorithms.tex#L13101)
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[*Note [1](#note-1)*:
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The difference between transform_exclusive_scan andtransform_inclusive_scan is that transform_inclusive_scan includes the ith input element in the ith sum[.](#8.sentence-1)
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If binary_op is not mathematically associative,
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the behavior of transform_inclusive_scan can be nondeterministic[.](#8.sentence-2)
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transform_inclusive_scan does not
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apply unary_op to init[.](#8.sentence-3)
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â *end note*]
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