std::incrementable(3)

💅 NAME 💅

std::incrementable — bestie, it's literally std::incrementable ✨

🦋 Synopsis 🦋

Okay so first things first, this whole thing lives in the header <iterator> 🎀

template< class I >

    concept incrementable =
        std::regular<I> &&
        std::weakly_incrementable<I> &&  (since C++20)
        requires(I i) {
            { i++ } -> std::same_as<I>;

        };

So what this concept actually does — no cap — is specify requirements on types that can be incremented with the pre- and post-increment operators 🫶. Their increment operations have to be equality-preserving, and the type has to be std::equality_comparable. That's the vibe check 💅.

And like, here's the glow-up: std::weakly_incrementable only supports single-pass algorithms 😭, but types that model std::incrementable can be used with multi-pass one-directional algorithms. She leveled up 👑.

✨ Semantic requirements ✨

I models std::incrementable only if, given any two incrementable objects a and b of type I:

• bool(a == b) implies bool(a++ == b), and
• bool(a == b) implies bool(((void)a++, a) == ++b).

Periodt 💀 those are the rules.

🌸 Equality preservation 🌸

Expressions declared in requires expressions of the standard library concepts are required to be equality-preserving (except where stated otherwise). Not me reminding you again, but yeah 💖.

⭐ See also ⭐

• weakly_incrementable (C++20) (concept) — specifies that a semiregular type can be incremented with pre- and post-increment operators
• same_as (C++20) (concept) — specifies that a type is the same as another type

okay that's the whole page bestie, go forth and increment responsibly 🧚💜

signed, sealed, delivered with love 💌 from http://cppreference.com, version/date 2024.06.10 — that's the std::incrementable(3) era, iykyk 🎀🔥