public/subjects/profanity_filter

profanity filter

Instructions

Sometimes it is more desirable to catch the failure of some parts of a program instead of just calling panic.

For this exercise you will have to create a message blocker, where you must block the word stupid

You will have to create a structure called Message, this structure must have the following elements:

• content: String
• user: String
• time_sent: String

The struct must also have a implementation of 2 functions associated to it:

• new, that initializes the structure
• send_ms, that only has its implementation type (self) as argument and returns an option. This function must return None if the content of the message is either empty or contains the word stupid. Otherwise it returns the content of the message.

You will have to create two more functions that aren't associated to any structure:

• check_ms that receives as parameters the reference to the structure Message and returns a tuple, containing a bool and a string. This function will execute the function send_ms and if the result of the option is None it should return (false, "ERROR: illegal"). Otherwise it returns true and the content of the message sent.
• date_format that creates and formats the date and time that the message was sent, the format should look like this: Mon Oct 5 10:22:19 2020

Expected Function

pub struct Message {}

impl Message {
  pub fn new(ms: String, u: String, t: String) -> Message {}
  pub fn send_ms(&self) -> Option<&str> {}
}

pub fn check_ms(ms: &Message) -> (bool, &str) {}
pub fn format_date() -> String {}

Usage

Here is a program to test your function

fn main() {
  let m0 = Message::new("hello there".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m0));

  let m1 = Message::new("".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m1));

  let m2 = Message::new("you are stupid".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m2));

  let m3 = Message::new("stupid".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m3));
}

And its output:

student@ubuntu:~/[[ROOT]]/test$ cargo run
(true, "hello there")
(false, "ERROR: illegal")
(false, "ERROR: illegal")
(false, "ERROR: illegal")
student@ubuntu:~/[[ROOT]]/test$

Notions

• https://docs.rs/chrono/0.4.19/chrono/
• https://doc.rust-lang.org/stable/book/ch06-01-defining-an-enum.html?highlight=option#the-option-enum-and-its-advantages-over-null-values