source: doc/theses/jiada_liang_MMath/test.rs@ 7d415b4

use std::mem;

enum WeekO { Mon, Tue, Wed, Thu, Fri, Sat, Sun }
#[derive(Debug, Clone, Copy)]
enum Week { Mon, Tue, Wed = 2, Thu = 10, Fri, Sat, Sun }

#[derive(Debug)]
struct S {
        i : isize, j : isize,
}
#[repr(u8)]
#[derive(Debug)]
enum ADT {
        I(isize) = 5,
        F(f64) = 10,
        S(S) = 0,
}

#[derive(Debug)]
enum Animal {
        Dog( String, f64 ),
        Cat{ name: String, weight: f64 },
}

#[derive(Debug)]
enum Direction { North, South, East, West }

impl Direction {
    const VALUES: [Self; 4] = [Self::North, Self::South, Self::East, Self::West];
}
#[repr(u8)]
enum Fieldless {
    Tuple() = 5,
    Struct{} = 10,
    Unit = 12,
}
impl Fieldless {
    fn discriminant(&self) -> u8 {
        // SAFETY: Because `Self` is marked `repr(u8)`, its layout is a `repr(C)` `union`
        // between `repr(C)` structs, each of which has the `u8` discriminant as its first
        // field, so we can read the discriminant without offsetting the pointer.
        unsafe { *<*const _>::from(self).cast::<u8>() }
    }
}
fn main() {
        let arr : [i32; 7];

        let mut s = S{ i : 3, j : 4 };
        let mut adt : ADT;
        adt = ADT::I(3);  println!( "{:?}", adt );
        adt = ADT::F(3.5);  println!( "{:?}", adt );
        adt = ADT::S(s);  println!( "{:?}", adt );
        match adt {
                ADT::I(i) => println!( "{:}", i ),
                ADT::F(f) => println!( "{:}", f ),
                ADT::S(s) => println!( "{:} {:}", s.i, s.j ),
        }

        let mut wo : WeekO = WeekO::Mon;
        match wo {
                WeekO::Mon => println!( "Mon" ),
                _ => (),
        }
        
        let mut fl : Fieldless;
        fl = Fieldless::Struct{};
        match fl {
                Fieldless::Struct{} => println!( "Struct" ),
                _ => (),
        }
        if fl.discriminant() == 10 {
                println!( "Struct" );
        }
        let mut week: Week = Week::Sat;
        match week {
                Week::Mon => println!( "X {:?}", Week::Mon as isize ),
                Week::Tue => println!( "X {:?}", Week::Tue as isize ),
                Week::Wed => println!( "X {:?}", Week::Wed as isize ),
                Week::Thu => println!( "X {:?}", Week::Thu as isize ),
                Week::Fri => println!( "X {:?}", Week::Fri as isize ),
                Week::Sat => println!( "X {:?}", Week::Sat as isize ),
                Week::Sun => println!( "X {:?}", Week::Sun as isize ),
        }
        match week {
                Week::Mon | Week:: Tue | Week::Wed | Week::Thu | Week::Fri => println!( "weekday" ),
                Week::Sat | Week:: Sun => println!( "weekend" ),
        }
        println!( "{:?} {:?}", week as isize, Week::Fri as isize );
        if mem::discriminant(&week) == mem::discriminant(&Week::Mon) {
                println!( "{:?}", week );
        }
        if week as isize == Week::Mon as isize {
                println!( "{:?}", week );
        }
        for d in Week::Mon as isize ..= Week::Sun as isize {
                print!( "{:?} ", d );
        }
        println!( "" );
        let mut mon : isize = Week::Mon as isize;

        week = Week::Fri;
        println!( "{:?}", week );

        let mut a: Animal = Animal::Dog("Cocoa".to_string(), 37.2);
        println!( "{:?}", a );
        a = Animal::Cat{ name: "Spotty".to_string(), weight: 2.7 };
//      println!( "{:?} {:?}", a, a.name );

        for direction in Direction::VALUES {
        println!("{direction:?}");
    }
}

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