Crate trie_match

trie_match! {}

This macro speeds up Rust’s match expression for comparing strings by using a compact double-array data structure.

Usage

Simply wrap the existing match expression with the trie_match! {} macro as follows:

use trie_match::trie_match;

let x = "abd";

let result = trie_match! {
    match x {
        "a" => 0,
        "abc" => 1,
        pat @ ("abd" | "bcde") => pat.len(),
        "bc" => 3,
        _ => 4,
    }
};

assert_eq!(result, 3);

cfg attribute

Only when using Nightly Rust, this macro supports conditional compilation with the cfg attribute. To use this feature, enable features = ["cfg_attribute"] in your Cargo.toml.

Example

use trie_match::trie_match;

let x = "abd";

let result = trie_match! {
    match x {
        #[cfg(not(feature = "foo"))]
        "a" => 0,
        "abc" => 1,
        #[cfg(feature = "bar")]
        "abd" | "bcc" => 2,
        "bc" => 3,
        _ => 4,
    }
};

assert_eq!(result, 4);

Limitations

The followings are different from the normal match expression:

• Only supports strings, byte strings, and u8 slices as patterns.
• The wildcard is evaluated last. (The normal match expression does not match patterns after the wildcard.)
• Guards are unavailable.

Macros

trie_match

Generates a match expression that uses a trie structure.