smol_str 0.2.2

small-string optimized string type with O(1) clone
Documentation

smol_str

CI Crates.io API reference

A SmolStr is a string type that has the following properties:

  • size_of::<SmolStr>() == 24 (therefore == size_of::<String>() on 64 bit platforms)
  • Clone is O(1)
  • Strings are stack-allocated if they are:
    • Up to 23 bytes long
    • Longer than 23 bytes, but substrings of WS (see src/lib.rs). Such strings consist solely of consecutive newlines, followed by consecutive spaces
  • If a string does not satisfy the aforementioned conditions, it is heap-allocated
  • Additionally, a SmolStr can be explicitly created from a &'static str without allocation

Unlike String, however, SmolStr is immutable. The primary use case for SmolStr is a good enough default storage for tokens of typical programming languages. Strings consisting of a series of newlines, followed by a series of whitespace are a typical pattern in computer programs because of indentation. Note that a specialized interner might be a better solution for some use cases.

MSRV Policy

Minimal Supported Rust Version: latest stable.

Bumping MSRV is not considered a semver-breaking change.