std::experimental::ranges::equal_to
Defined in header <experimental/ranges/functional>
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||
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template
<
class T =
void
>
requires EqualityComparable<T>
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(ranges TS) | |
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template
<>
struct equal_to< void > ; |
(ranges TS) | |
Function object for performing comparisons. The primary template invokes operator == on const lvalues of type T. The specialization equal_to<void>
All specializations of equal_to are Semiregular.
Member types
| Member type | Definition |
is_transparent (member only of equal_to<void> specialization)
|
/* unspecified */ |
Member functions
operator() |
checks if the arguments are equal (public member function) |
std::experimental::ranges::equal_to::operator()
|
constexpr
bool operator(
)
(
const T& x, const T& y)
const
;
|
(1) | (member only of primary equal_to<T> template) |
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template
<
class T, class U >
requires EqualityComparableWith<T, U>
||
|
(2) | (member only of equal_to<void> specialization) |
t and u. Equivalent to
return
std::forward
<T>
(t)
==
std::forward
<U>
(u)
;
, except when that expression resolves to a call to a builtin operator ==
When a call to (1) or (2) would invoke a built-in operator comparing pointers of type P, the result is instead determined as follows:
- Returns
false
if one of the (possibly converted) value of the first argument and the (possibly converted) value of the second argument precedes the other in the implementation-defined strict total ordering over all pointer values of type
P. This strict total ordering is consistent with the partial order imposed by the builtin operators<,>,<=, and>= - Otherwise (neither precedes the other), returns true.
The behavior is undefined unless the conversion sequences from both T and U to P are equality-preserving (see below).
Equality preservation
An expression is equality preserving if it results in equal outputs given equal inputs.
- The inputs to an expression consist of its operands.
- The outputs of an expression consist of its result and all operands modified by the expression (if any).
Every expression required to be equality preserving is further required to be stable
Notes
Unlike std::equal_to, ranges::equal_to requires both == and != to be valid (via the EqualityComparable and EqualityComparableWith
Example
| This section is incomplete Reason: no example |
See also
| function object implementing x == y (class template) |