std::experimental::ranges::less_equal

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< cpp‎ | experimental‎ | ranges
 
 
Technical specifications
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Library fundamentals (library fundamentals TS)
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Extensions for parallelism 2 (parallelism TS v2)
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General utilities library
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Function objects
less_equal
Metaprogramming and type traits
Tagged pairs and tuples
                                        
                                        
                                        
                                        
 
template< class T = void >

    requires StrictTotallyOrdered<T> ||
             Same<T, void> ||
             /* < on two const T lvalues invokes a built-in operator comparing pointers */

struct less_equal;
(ranges TS)
template <>
struct less_equal<void>;
(ranges TS)

Function object for performing comparisons. The primary template invokes operator< on const lvalues of type T with the argument order inverted and then negates the result. The specialization less_equal<void> deduces the parameter types of the function call operator from the arguments (but not the return type).

All specializations of less_equal are Semiregular.

Member types

Member type Definition
is_transparent (member only of less_equal<void> specialization) /* unspecified */

Member functions

operator()
checks if the first argument is less than or equal to the second
(public member function)

std::experimental::ranges::less_equal::operator()

constexpr bool operator()(const T& x, const T& y) const;
(1) (member only of primary less_equal<T> template)
template< class T, class U >

    requires StrictTotallyOrderedWith<T, U> ||
             /* std::declval<T>() < std::declval<U>() resolves to
                a built-in operator comparing pointers */

constexpr bool operator()(T&& t, U&& u) const;
(2) (member only of less_equal<void> specialization)
1) Compares x and y. Equivalent to return !ranges::less<>{}(y, x);
2) Compares t and u. Equivalent to return !ranges::less<>{}(std::forward<U>(u), std::forward<T>(t));.

Notes

Unlike std::less_equal, ranges::less_equal requires all six comparison operators <, <=, >, >=, == and != to be valid (via the StrictTotallyOrdered and StrictTotallyOrderedWith constraints) and is entirely defined in terms of ranges::less. However, the implementation is free to use operator<= directly, because those concepts require the results of the comparison operators to be consistent.

Example

See also

function object implementing x <= y
(class template)