std::experimental::ranges::equal_to

 

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swap	exchange
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invoke identity	equal_to not_equal_to	greater less	greater_equal less_equal
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Defined in header <experimental/ranges/functional>
template <class T = void>     requires /* see below */ struct equal_to;		(ranges TS)

Function object for performing comparisons. Unless specialized, invokes operator == on type T.

Parameters

T	-	object type
Type requirements
- T must meet one of the following requirements: EqualityComparable, Same<T, void> or BUILTIN_PTR_CMP (const T&, ==, const T&)(see below).

Member functions

operator()

checks if the arguments are equal (public member function)

operator() has effects equivalent to: return equal_to<>(x, y);

Notes

In this section, BUILTIN_PTR_CMP (T, op, U) for types T and U and where op is an equality or relational operator is a boolean constant expression. BUILTIN_PTR_CMP (T, op, U) is true if and only if op in the expression declval<T>() op declval<U>() resolves to a built-in operator comparing pointers. There is an implementation-defined strict total ordering over all pointer values of a given type. This total ordering is consistent with the partial order imposed by the builtin operators <, >, <=, and >=.

Specializations

template <> struct equal_to<void> {
    template <class T, class U>
        requires EqualityComparableWith<T, U> || BUILTIN_PTR_CMP (T, ==, U)
    constexpr bool operator()(T&& t, U&& u) const;
 
    typedef /* unspecified */ is_transparent;
};

1) Requires:

• If the expression std::forward<T>(t) == std::forward<U>(u) results in a call to a builtin operator == comparing pointers of type P, the conversion sequences from both T and U to P shall be equality-preserving.

2) Effects:

• If the expression std::forward<T>(t) == std::forward<U>(u) results in a call to a built-in operator == comparing pointers of type P: returns false if either (the converted value of) t precedes u or u precedes t in the implementation-defined strict total order over pointers of type P and otherwise true.
• Otherwise, equivalent to: return std::forward<T>(t) == std::forward<U>(u);

See also

equal_to

function object implementing x == y (class template)