std::experimental::ranges::StrictWeakOrder

From cppreference.com
< cpp‎ | experimental‎ | ranges
 
 
Technical specifications
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals TS v2)
Library fundamentals 3 (library fundamentals TS v3)
Extensions for parallelism (parallelism TS)
Extensions for parallelism 2 (parallelism TS v2)
Extensions for concurrency (concurrency TS)
Extensions for concurrency 2 (concurrency TS v2)
Concepts (concepts TS)
Ranges (ranges TS)
Reflection (reflection TS)
Mathematical special functions (special functions TR)
 
 
Concepts library
Core language concepts
                              
Object concepts
                              
                              
Comparison concepts
Callable concepts
                                        
                              
StrictWeakOrder

URNG concept
 
template < class R, class T, class U >
concept bool StrictWeakOrder = Relation<R, T, U>;
(1) (ranges TS)

The concept StrictWeakOrder<R, T, U> specifies that the Relation R imposes a strict weak ordering on its arguments. A relation r is a strict weak ordering if

  • it is irreflexive: for all x, r(x, x) is false;
  • it is transitive: for all a, b and c, if r(a, b) and r(b, c) are both true then r(a, c) is true;
  • let e(a, b) be !r(a, b) && !r(b, a), then e is transitive: e(a, b) && e(b, c) implies e(a, c).

Under these conditions, it can be shown that e is an equivalence relation, and r induces a strict total ordering on the equivalence classes determined by e.

Notes

The distinction between Relation and StrictWeakOrder is purely semantic.