public/subjects/lunch_queue

lunch_queue

Instructions

An API will have to be created to organize a queue of people.

Using the given code declare the following functions:

• new which will initialize the Queue
• add which receives the person's information, so it can be added to the Queue
• invert_queue which inverts the queue of persons
• rm, which will remove the person who finished ordering their food. The removal should respect a FIFO system (first in first out). This function should return a tuple wrapped in an Option with the information of the removed person (check the usage)
• search, which returns a tuple with the information of a given person id

You must also create a type called Link. This will be the connection of the structures Queue and Person. Do not forget that this will be a recursion type and it must point to None if there is no persons.

Notions

• enum
• Box
• std::option

Expected Function adn Structures

pub struct Queue {
    pub node: Link,
}

pub type Link =

pub struct Person {
    pub id: i32,
    pub name: String,
}

impl Queue {
    pub fn new() -> Queue {}
    pub fn add(&mut self, t: String, name: String) {}
    pub fn invert_queue(&mut self) {}
    pub fn rm(&mut self) -> Option<String> {}
    pub fn search(&self) -> Option<(String, String)> {}

}

Usage

Here is a program to test your function:

fn main() {
    let mut list = Queue::new();
    list.add(String::from("Marie"), 20);
    list.add(String::from("Monica"), 15);
    list.add(String::from("Ana"), 5);
    list.add(String::from("Alice"), 35);
    println!("{:?}", list);

    println!("{:?}", list.search("Marie"));
    println!("{:?}", list.search("Alice"));
    println!("{:?}", list.search("someone"));

    println!("removed {:?}", list.rm());
    println!("list {:?}", list);
    list.invert_queue();
    println!("invert {:?}", list);
}

And its output:

$ cargo run
Queue { node: Some(Person { name: "Alice", discount: 35, next_person: Some(Person { name: "Ana", discount: 5, next_person: Some(Person { name: "Monica", discount: 15, next_person: Some(Person { name: "Marie", discount: 20, next_person: None }) }) }) }) }
Some(("Marie", 20))
Some(("Alice", 35))
None
removed Some(("Marie", 20))
list Queue { node: Some(Person { name: "Alice", discount: 35, next_person: Some(Person { name: "Ana", discount: 5, next_person: Some(Person { name: "Monica", discount: 15, next_person: None }) }) }) }
invert Queue { node: Some(Person { name: "Monica", discount: 15, next_person: Some(Person { name: "Ana", discount: 5, next_person: Some(Person { name: "Alice", discount: 35, next_person: None }) }) }) }
$