mysql::ranges::Is_collection Concept Reference

True if Test has the properties of a "collection", i.e., a range with member functions to query size and emptiness. More...

#include <meta.h>

Concept definition

template<class Test>
concept mysql::ranges::Is_collection = 
    requires(const Test ct, Test t)  
{
  { t.begin() } -> std::forward_iterator;
  { t.end() } -> std::sentinel_for<decltype(t.begin())>;
  { ct.begin() } -> std::forward_iterator;
  { ct.end() } -> std::sentinel_for<decltype(ct.begin())>;
  { ct.size() } -> std::same_as<std::size_t>;
  { ct.ssize() } -> std::same_as<std::ptrdiff_t>;
  { ct.empty() } -> std::same_as<bool>;
  { (bool)ct } -> std::same_as<bool>;
}

Detailed Description

True if Test has the properties of a "collection", i.e., a range with member functions to query size and emptiness.

It requires the following:

• t.begin() returns a forward iterator
• t.end() returns a sentinel for t.begin()
• t.size() returns std::size_t
• t.ssize() returns std::ptrdiff_t
• t.empty() and (bool)t return bool

In addition, the following semantic requirements must hold:

• t.size() == std::ranges::distance(t.begin(), t.end())
• t.ssize() == std::ptrdiff_t(t.size())
• t.empty() == (t.size() == 0)
• t.empty() == !(bool)t