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Sometimes, you only need to handle a specific case of an enum variant, in this case using a match statement can be overkill. Rust provides a more concise way to handle such cases using the if let construct. This allows you to match a single variant of an enum and extract its value in a single line.

Here's an example:

enum Ip {
    V4(String),
    V6(String),
}


if let Ip::V4(ip) = &ip {
    println!("IPv4 address: {}", ip);
}

Your Task

You are provided an enum called Message with the following variants:

  • Text(String): Represents a textual message.
  • Number(i32): Represents a numerical message.
  • Quit: Represents a command to quit.
  • None: Represents no message.

Your task is to implement the function process_text_message that takes a reference to a Message enum. For the Text variant, the function should return "Processed Text: <content>", replacing <content> with the actual string.

If the input is any other variant of the enum, the function should return "Unhandled Message".

Try to solve this using the if let construct.

Hints

<details> <summary>Click here to reveal hints</summary>
  • You can use the if let construct like this: 
    if let EnumVariant(value) = &enum_instance {
        // Perform actions with `value`.
    }
  • Ensure you return "Unhandled Message" for all other variants not explicitly matched.
</details>
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pub enum Message {
    Text(String),
    Number(i32),
    Quit,
    None,
}


pub fn process_text_message(message: &Message) -> String {
    // Your code here...


    String::from("Unhandled Message")
}


pub fn main() {
    assert_eq!(
        process_text_message(&Message::Text(String::from("Hello"))),
        "Processed Text: Hello"
    );
    assert_eq!(
        process_text_message(&Message::Number(42)),
        "Unhandled Message"
    );
    assert_eq!(process_text_message(&Message::Quit), "Unhandled Message");
    assert_eq!(process_text_message(&Message::None), "Unhandled Message");
}