https://doc.rust-lang.org/stable/rust-by-example/custom_types/enum.html

enum_match_ex.rs

/*--------------------------------------------------------------------------------------------------------------
 * Copyright (c) Microsoft Corporation. All rights reserved.
 * Licensed under the MIT License. See https://go.microsoft.com/fwlink/?linkid=2090316 for license information.
 *-------------------------------------------------------------------------------------------------------------*/

struct StA {
    a: i64,
    b: i64,
}

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

// A function which takes a `WebEvent` enum as an argument and
// returns nothing.
fn inspect(event: WebEvent) {
    match event {
        WebEvent::PageLoad => println!("page loaded"),
        WebEvent::PageUnload => println!("page unloaded"),
        // Destructure `c` from inside the `enum`.
        WebEvent::KeyPress(c) => println!("pressed '{}'.", c),
        WebEvent::Paste(s) => println!("pasted \"{}\".", s),
        // Destructure `Click` into `x` and `y`.
        WebEvent::Click { x, y } => {
            println!("clicked at x={}, y={}.", x, y);
        }
        WebEvent::Touch { x, y, z } => {
            println!("clicked at x={}, y={}, z={}", x, y, z);
        }
        WebEvent::T(st) => {
            println!("StA, a={}, b={}", st.a, st.b);
        }
    }
}

fn main() {
    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 touch = WebEvent::Touch {
        x: 20,
        y: 80,
        z: 100,
    };
    let load = WebEvent::PageLoad;
    let unload = WebEvent::PageUnload;
    let st = WebEvent::T(StA { a: 10, b: 10 });

    inspect(pressed);
    inspect(pasted);
    inspect(click);
    inspect(load);
    inspect(unload);
    inspect(touch);
    inspect(st);
}