25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.1 General [range.adaptors.general]

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Subclause [range.adaptors] defines range adaptors, which are utilities that transform a range into a view with custom behaviors.
These adaptors can be chained to create pipelines of range transformations that evaluate lazily as the resulting view is iterated.
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Range adaptors are declared in namespace std​::​ranges​::​views.
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The bitwise or operator is overloaded for the purpose of creating adaptor chain pipelines.
The adaptors also support function call syntax with equivalent semantics.
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[Example 1: vector<int> ints{0,1,2,3,4,5}; auto even = [](int i) { return 0 == i % 2; }; auto square = [](int i) { return i * i; }; for (int i : ints | views::filter(even) | views::transform(square)) { cout << i << ' '; // prints 0 4 16 } assert(ranges::equal(ints | views::filter(even), views::filter(ints, even))); — end example]