🧠 LRU Cache for MoonBit

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LRU Cache is a high-performance Least Recently Used (LRU) cache implementation in MoonBit. It provides constant-time complexity for common operations and automatically manages capacity with an efficient eviction policy.

🚀 Key Features

⚡ Fast Operations – All operations run in O(1) time complexity
🔄 Automatic Eviction – Automatically removes least recently used items when capacity is reached
🛠 Easy to Use – Simple API for quick integration
✅ Well-Tested – Comes with comprehensive unit tests
🔧 Type Safe – Fully type-safe implementation for any key-value pair types

📥 Installation

moon add ShellWen/lru_cache

🚀 Usage Guide

Basic Usage

The simplest way to use the LRU cache is to create a new instance with a specified capacity:

// Create a cache with capacity 100
let cache : LruCache[String, Int] = LruCache::new(100)

// Add items to cache
cache.put("key1", 100)
cache.put("key2", 200)

// Get items from cache
let value1 = cache.get("key1") // Returns Some(100)
let value2 = cache.get("nonexistent") // Returns None

Key Features Explained

1. Automatic Eviction

When the cache reaches its capacity, the least recently used item is automatically removed:

let cache : LruCache[String, Int] = LruCache::new(2) // Cache with capacity 2
cache.put("key1", 100)
cache.put("key2", 200)
cache.put("key3", 300) // This will evict "key1" as it's the least recently used

let val1 = cache.get("key1") // Returns None, as "key1" was evicted
let val2 = cache.get("key2") // Returns Some(200)
let val3 = cache.get("key3") // Returns Some(300)

2. LRU Order Update

Items are reordered when accessed, keeping the most recently used items in the cache:

let cache : LruCache[String, Int] = LruCache::new(2)
cache.put("key1", 100)
cache.put("key2", 200)

// Accessing "key1" makes it the most recently used
let _ = cache.get("key1")

// Adding a new item will now evict "key2" instead of "key1"
cache.put("key3", 300)

let val1 = cache.get("key1") // Returns Some(100)
let val2 = cache.get("key2") // Returns None, as "key2" was evicted
let val3 = cache.get("key3") // Returns Some(300)

3. Custom Key Types

You can use any key type that implements Eq + Hash:

struct CustomKey { id: Int } derive(Eq, Hash)

let cache : LruCache[CustomKey, String] = LruCache::new(10)
cache.put({id: 1}, "Value for key 1")
cache.put({id: 2}, "Value for key 2")

let value = cache.get({id: 1}) // Returns Some("Value for key 1")

📖 API Reference

Run moon doc --serve to view the API documentation.

📜 License

This project is licensed under the Apache License 2.0. See LICENSE for details.

📢 Contact & Support

Author: ShellWen Chen me@shellwen.com
GitHub Issues: Report an issue

👋 If you like this project, give it a ⭐! Happy coding! 🚀

ShellWen/lru-cache-mbt