std::equal_...,less_equal,(3)

💅 std::equal_to, not_equal_to, less, greater, less_equal, greater_equal 💅

okay so bestie, welcome to the C++ Standard Libary (3) manual page — page tag std::equal_...,less_equal,(3), manual name folded in right here, and we are not doing a boring copy-paste header line. This page is about the standard comparison function objects being partially specialized for std::experimental::propagate_const<T>. It's niche! It's specific! It's giving library-fundamentals-TS-v2 realness, and honestly? iconic. 🦋✨

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🌸 NAME 🌸

The NAME line is literally this, truncated energy and all:

std::equal_to,not_equal_to,less,greater,less_equal, -
std::equal_to,not_equal_to,less,greater,less_equal,

no cap, we're keeping it exactly like that. 💅

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✨ Synopsis ✨

Defined in header <experimental/propagate_const>.

template< class T > struct equal_to<std::experimental::propagate_const<T>>;
template< class T > struct not_equal_to<std::experimental::propagate_const<T>>;
template< class T > struct less<std::experimental::propagate_const<T>>;
template< class T > struct greater<std::experimental::propagate_const<T>>;
template< class T > struct less_equal<std::experimental::propagate_const<T>>;
template< class T > struct greater_equal<std::experimental::propagate_const<T>>;

Each one of those is tagged (library fundamentals TS v2) in the original. periodt. 🎀

The standard comparison function objects are partially specialized for std::experimental::propagate_const<T>.

Let p.t_ denote the pointer-like object wrapped by a std::experimental::propagate_const<T> p, then given objects p and q of type std::experimental::propagate_const<T>, the following shall hold:

• std::equal_to<std::experimental::propagate_const<T>>()(p, q) == std::equal_to<T>()(p.t_, q.t_)
• std::not_equal_to<std::experimental::propagate_const<T>>()(p, q) == std::not_equal_to<T>()(p.t_, q.t_)
• std::less<std::experimental::propagate_const<T>>()(p, q) == std::less<T>()(p.t_, q.t_)
• std::greater<std::experimental::propagate_const<T>>()(p, q) == std::greater<T>()(p.t_, q.t_)
• std::less_equal<std::experimental::propagate_const<T>>()(p, q) == std::less_equal<T>()(p.t_, q.t_)
• std::greater_equal<std::experimental::propagate_const<T>>()(p, q) == std::greater_equal<T>()(p.t_, q.t_)

These are the exact requirements, bestie. The vibes are mathematical. 🫶

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💭 Notes 💭

Lowkey the whole point: these specializations ensure that when T is a pointer type, specializations of these class templates for std::experimental::propagate_const<T> yield a total order, even if the corresponding built-in operators do not. Slay for total order, periodt. 🔥

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😭 Example 😭

This section is incomplete Reason: no example

not me showing up with zero example — that's literally what the page says, so we're not inventing one. 🙈

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🦋 See also 🦋

• equal_to — function object implementing x == y (class template)
• not_equal_to — function object implementing x != y (class template)
• less — function object implementing x < y (class template)
• greater — function object implementing x > y (class template)
• less_equal — function object implementing x <= y (class template)
• greater_equal — function object implementing x >= y (class template)

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🎀 Category: 🎀

• Todo no example

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mwah 💋 — source/version: http://cppreference.com; date: 2024.06.10; page tag: std::equal_...,less_equal,(3). byeee bestie 🫶🌈