Jeff Garland

Intro

• The beginning of the end – for begin and end

Basics

std::sort(a.begin(), a.end())

Instead:

ranges::sort(a);

Example with find_if

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the ranges way: filter_view

for (int i : rng::filter_view (a, is_six)) { std::cout << i << “ “; }

Tristan Brindel NanoRange

Godbolt

• supports several
• range: something that can be iterator over
• range algo: algorithm that takes range
• view: lazy range thats cheap top copy
• ranger adapter: turn range into a view

mechanics

• 3 new names ranges, ranges::views, views = ranges::views

Why new namespaces

• behavior and guaranteed of some algorithms are changed

What’s a range

• iterator pair is simplest
• sentinel and iterator can be different types
• ranges can be infinite
• any container with begin()/end() can be used in a range

Views are ranged with lazy evaluation

• non-owning of elements
• all methods

  O(1)

  for copy and assignment

range adaptors -> views from ranges

• pipeline syntax

filter_view adaptor

for (int i = range_filter_view (vi, is_event))

No more for loops

Range Algorithm details

• list of range algorithms

Projection parameters

• provides first class filtering predicate
• comes from the Adobe Source Libraries (ASL)

ranges::sort(vistuff, std::less<>{}, [](auto const &i) {return i.value;})

Views and View Adaptor details

How do ranges perform

• Compile time: no noticeable difference
• runtime: nothing expected over stl algorithms

Resources

wg21.link/n4810

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