• Overview
  • Why bother?
• Copyright

Overview

This package provides a fast, memory-efficient mapping from values of an arbitrary (hashable) type to whole numbers. Read-only references to a symbol table are thread-safe.

Why bother?

You can get a lot of this package's functionality with a structure like:

pub struct Table<T> where T: Hash + Eq {
    // Mapping from T to usize.
    by_symbol: HashMap<T, usize>,
    // Mapping from usize to T.
    by_id: Vec<T>,
}

But then you're maintaining an extra copy of each T. You can resort to a HashMap<Rc<T>, usize> and Vec<Rc<T>>, but that forces you to pay the cost of reference counting and isn't easily shared across threads. Using Arc instead of Rc makes your type Send-able, but that has even more overhead than using Rc.

Or you could use search_table::HashIndexing<T> and get a type that is Send and Sync when T is and owns only one T per association in the table.

Copyright

Copyright 2016, Alphabet. All rights reserved.