std::experimental::ranges::tag::in, in1, in2, out, out1, out2, fun, min, max, begin, end

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Technical specifications
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals 2 TS)
Extensions for parallelism (parallelism TS)
Extensions for parallelism 2 (parallelism TS v2)
Extensions for concurrency (concurrency TS)
Concepts (concepts TS)
Ranges (ranges TS)
Special mathematical functions (special math TR)
 
 
General utilities library
Utility components
Function objects
Metaprogramming and type traits
Tagged pairs and tuples
                                        
tag specifiers
                                        
                                        
                                        
 
struct in { /* implementation-defined */ };

struct in1 { /* implementation-defined */ };
struct in2 { /* implementation-defined */ };
struct out { /* implementation-defined */ };
struct out1 { /* implementation-defined */ };
struct out2 { /* implementation-defined */ };
struct fun { /* implementation-defined */ };
struct min { /* implementation-defined */ };
struct max { /* implementation-defined */ };
struct begin { /* implementation-defined */ };

struct end { /* implementation-defined */ };
(ranges TS)

These classes are TagSpecifiers for use with ranges::tagged.

The name of a specifier is also the element name it corresponds to. For instance, ranges::tagged<std::pair<int, int>, tag::min, tag::max> provides a set of named accessors named min and a set of named accessors named max.