Crate strpool

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Expand description

String Pools / Strings Interning

§Features

  • quick Deref<str> implementation - one pointer resolution, one comparison, and one pointer increment
  • thin PoolStr type - a pointer
  • The pool is deallocated only when every object referencing it have been dropped.
  • no_std, but alloc is required
  • thread-safe
  • Pool’s Debug implementation allows you to see all of its strings
  • simple O(n / P) insertion/search, where P is Pool’s const generic parameter

§Example


// you can reduce insertion/search complexity by raising this number,
// at the expense of more frequent allocations for small strings.
// strings are spread evenly into these subpools based on their hash.
// => must be a non-zero power of two.
const SUB_POOLS: usize = 1;

// no need for mutability, the pool uses atomic operations
let pool: Pool<SUB_POOLS> = Pool::new();

// use Pool::intern(&self, &str) to insert a string slice into the pool
// if the string was already present, that PoolStr will be reused.
let pool_string = pool.intern("Hello world!");

// you can obtain a &str with the Deref implementation
assert_eq!(pool_string.deref(), "Hello world!");
// Hash, Eq, Debug, Display are implemented as well.

// you can use Pool::find(&self, &str) to check if the pool contains a string
assert_eq!(pool.find("oh hi mark"), None);

// the empty string doesn't rely on a pool, it's always there
assert_eq!(pool.find(""), Some(PoolStr::empty()));

// See all interned strings via the Debug implementation
println!("{:#?}", pool);

§Internal Memory Structure (Example)

memory.png

Structs§