Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2023. The current version is 1.90.0.

grammar::string_view_base::npos

A constant used to represent "no position".

static
constexpr std::size_t npos = string_view::npos;