rustc/vendor/string_cache-0.8.7

string-cache

Documentation

A string interning library for Rust, developed as part of the Servo project.

Simple usage

In Cargo.toml:

[dependencies]
string_cache = "0.8"

In lib.rs:

extern crate string_cache;
use string_cache::DefaultAtom as Atom;

With static atoms

In Cargo.toml:

[package]
build = "build.rs"

[dependencies]
string_cache = "0.8"

[build-dependencies]
string_cache_codegen = "0.5"

In build.rs:

extern crate string_cache_codegen;

use std::env;
use std::path::Path;

fn main() {
    string_cache_codegen::AtomType::new("foo::FooAtom", "foo_atom!")
        .atoms(&["foo", "bar"])
        .write_to_file(&Path::new(&env::var("OUT_DIR").unwrap()).join("foo_atom.rs"))
        .unwrap()
}

In lib.rs:

extern crate string_cache;

mod foo {
    include!(concat!(env!("OUT_DIR"), "/foo_atom.rs"));
}

The generated code will define a FooAtom type and a foo_atom! macro. The macro can be used in expression or patterns, with strings listed in build.rs. For example:

fn compute_something(input: &foo::FooAtom) -> u32 {
    match *input {
        foo_atom!("foo") => 1,
        foo_atom!("bar") => 2,
        _ => 3,
    }
}