enum_dict

A Rust library for efficient enum-indexed dictionaries.

Installation

Add to your Cargo.toml:

[dependencies]
enum_dict = { version = "0.3", features = ["full"] }

Quick Start

use enum_dict::{DictKey, required_dict, optional_dict};

#[derive(DictKey)]
enum Color {
    Red,
    Green,
    Blue,
}

fn main() {
    // `RequiredDict` - all keys must have values
    let mut colors = required_dict! {
        Color::Red => "#FF0000",
        Color::Green => "#00FF00",
        Color::Blue => "#0000FF",
    };

    // Direct indexing - no `.get()` needed!
    println!("Red hex: {}", colors[Color::Red]);

    // Mutable access
    colors[Color::Red] = "#FF0001";

    // `OptionalDict` - keys may or may not have values
    let favorite_colors = optional_dict! {
        Color::Blue => "Sky Blue",
    };

    // Returns `Option<&str>`
    if let Some(favorite) = favorite_colors[Color::Blue] {
        println!("Favorite blue: {}", favorite);
    }
}

Serde Support

With the serde feature enabled, RequiredDict and OptionalDict can be serialized and deserialized using serde:

use enum_dict::{DictKey, RequiredDict};
use serde::{Serialize, Deserialize};

#[derive(DictKey)]
enum Locale {
    EN,
    FR,
    JP,
    ZH,
}

#[derive(Serialize, Deserialize)]
struct I18nMessage {
    translations: RequiredDict<Locale, String>,
}

Extra keys in the serialized data are ignored during deserialization.

Why enum_dict?

Compared to traditional HashMap approach, enum_dict uses Vec under the hood, allowing for:

• Direct Indexing: Access values with dict[key] instead of dict.get(&key).
• Performance: Faster access times due to contiguous memory layout.
• Type Safety: Compile-time checks ensure all enum variants are handled.
• Simplicity: Less boilerplate code for common use cases.