VisualByteOrg

Pattern matching with enum types in Rust

use std::arch::asm;

enum WebEvent {
    // An `enum` variant may either be `unit-like`,
    PageLoad,
    PageUnload,
    // like tuple structs,
    KeyPress(char),
    Paste(String),
    // or c-like structures.
    Click { x: i64, y: i64 },
}

// A function which takes a `WebEvent` enum as an argument and
// returns nothing.
fn inspect(event: WebEvent) {
    unsafe{
        asm!("int 3");
    }
    match event {
        WebEvent::PageLoad                    => println!("page loaded"),
        WebEvent::PageUnload                  => println!("page unloaded"),
        // Destructure `c` from inside the `enum` variant.
        WebEvent::KeyPress(c)           => println!("pressed '{}'.", c),
        WebEvent::Paste(s)            => println!("pasted \"{}\".", s),
        // Destructure `Click` into `x` and `y`.
        WebEvent::Click { x: 30, y }     => { println!("x must be 30, clicked at x={}, y={}.", 30, y); },
        WebEvent::Click { x, y }    => { println!("clicked at x={}, y={}.", x, y);},
    }
}

fn main() {
    //enum
    let pressed = WebEvent::KeyPress('x');
    // `to_owned()` creates an owned `String` from a string slice.
    let pasted  = WebEvent::Paste("my text".to_owned());
    let click   = WebEvent::Click { x: 20, y: 80 };
    let click_y   = WebEvent::Click { x: 30, y: 40 };
    let load    = WebEvent::PageLoad;
    let unload  = WebEvent::PageUnload;

    inspect(pressed);
    inspect(pasted);
    inspect(click);
    inspect(click_y);
    inspect(load);
    inspect(unload);
}