**Course Title:** Mastering Rust: From Basics to Systems Programming **Section Title:** Collections and Iterators **Topic:** Create a Rust program that utilizes collections and iterators effectively. ### Introduction In the previous topics, we discussed the basics of Rust's collection types and introduced iterators as a way to work with these collections. In this lab topic, we'll put this knowledge into practice by creating a Rust program that utilizes collections and iterators effectively. We'll explore a real-world scenario and see how to apply concepts to solve a problem. ### Problem Statement Suppose we're building a simple library management system that allows us to store books, authors, and genres. We want to be able to store this data in a way that allows for efficient querying and manipulation. ### Solution Overview To solve this problem, we'll use the following collections and iterators: * `HashMap` to store books with their corresponding authors and genres. * `HashSet` to store unique genres and authors. * Iterators to query and manipulate the data. ### Step 1: Setting Up the Program First, let's set up a new Rust project using Cargo: ```bash cargo new library_management ``` Next, add the following dependencies to your `Cargo.toml`: ```toml [dependencies] serde = { version = "1.0", features = ["derive"] } serde_json = "1.0" ``` ### Step 2: Defining the Data Structures In the `src/main.rs` file, define the following data structures: ```rust use std::collections::{HashMap, HashSet}; #[derive(Debug, Serialize, Deserialize)] struct Book { title: String, author: String, genre: String, } fn main() { // Create a HashMap to store books let mut book_collection = HashMap::new(); // Create a HashSet to store unique genres let mut genres = HashSet::new(); // Create a HashSet to store unique authors let mut authors = HashSet::new(); // Add some sample data book_collection.insert( "To Kill a Mockingbird", Book { title: String::from("To Kill a Mockingbird"), author: String::from("Harper Lee"), genre: String::from("Fiction"), }, ); genres.insert(String::from("Fiction")); authors.insert(String::from("Harper Lee")); // Add more books... } ``` ### Step 3: Working with Iterators Now that we have our data stored, let's use iterators to query and manipulate the data. For example, let's find all books written by a specific author: ```rust // Find all books written by Harper Lee let lee_books: Vec<Book> = book_collection .values() .filter(|book| book.author == "Harper Lee") .cloned() .collect(); println!("Books by Harper Lee: {:?}", lee_books); ``` ### Step 4: Serializing and Deserializing Data We can use the `serde` and `serde_json` crates to serialize and deserialize our data to and from JSON: ```rust use serde_json; // Serialize the book collection to JSON let json_collection = serde_json::to_string_pretty(&book_collection).unwrap(); println!("Serialized collection: {}", json_collection); // Deserialize the JSON back into a HashMap let deserialized_collection: HashMap<String, Book> = serde_json::from_str(&json_collection).unwrap(); println!("Deserialized collection: {:?}", deserialized_collection); ``` ### Conclusion In this lab topic, we created a Rust program that utilizes collections and iterators effectively to solve a real-world problem. We used `HashMap` and `HashSet` to store data and iterators to query and manipulate the data. Finally, we serialized and deserialized the data to and from JSON using `serde` and `serde_json`. ### Practice Takeaways * Use `HashMap` and `HashSet` to store data in Rust. * Use iterators to query and manipulate collections. * Serialize and deserialize data to and from JSON using `serde` and `serde_json`. ### Resources * [The Rust Book: Chapter 8 - Common Collections](https://doc.rust-lang.org/book/ch08-00-common-collections.html) * [The Rust Standard Library: std::collections](https://doc.rust-lang.org/std/collections/index.html) * [serde and serde_json crates](https://crates.io/crates/serde) and [https://crates.io/crates/serde_json](https://crates.io/crates/serde_json) If you have any questions or need help, ask away! You can also leave a comment below.