Macro peripherals::field_type

macro_rules! field_type {
    ($(#[$($attr:tt)*])* enum $name:ident $int:tt {
        $(#[$variant1_attr:meta])*
        $variant1:ident = $value1:literal,
        $(#[$variant2_attr:meta])*
        $variant2:ident = $value2:literal $(,)?
    }) => { ... };
    ($(#[$($attr:tt)*])* enum $name:ident $int:tt {$(
        $(#[$variant_attr:meta])*
        $variant:ident = $value:literal
    ),*$(,)?}) => { ... };
    ($(#[$($attr:tt)*])* struct $name:ident $int:tt (bool);) => { ... };
    ($(#[$($attr:tt)*])* struct $name:ident $int:tt ($inner:ty);) => { ... };
}

A helper hacro to define a type that can be used in field value.

It can define either an enum or a newtype struct. It also implement into and try_from for the given interger types. For an example of the generated types, see the example module.

Usage

use core::convert::{TryFrom, TryInto};

// Define an enum
peripherals::field_type! {
    enum Mode [u8, u16] {
        A = 0,
        B = 1,
        C = 2,
        D = 3,
    }
}

// It implements into and try_from for given interger types (here u8 and u16)
assert_eq!(Into::<u8>::into(Mode::A), 0);
assert_eq!(u16::from(Mode::B), 1);
assert_eq!(TryInto::<Mode>::try_into(2_u8), Ok(Mode::C));
assert_eq!(Mode::try_from(3_u16), Ok(Mode::D));

// Define a newtype struct
peripherals::field_type! {
    struct Data [u16] (u8);
}

// It implements into and try_from for given interger types (here u16)
assert_eq!(u16::from(Data(10)), 10);
assert_eq!(Data::try_from(20), Ok(Data(20)));

It also implements Not for enum with two fields and newtypes over bool. Fields with these types can be toggled.

use core::convert::{TryFrom, TryInto};

// Define an enum with two variants
peripherals::field_type! {
    enum State [] {
        Low = 0,
        High = 1,
    }
}

// It implements Not
assert_eq!(!State::Low, State::High);
assert_eq!(!State::High, State::Low);

// Define a newtype struct over a bool
peripherals::field_type! {
    struct Status [] (bool);
}

// It implements Not
assert_eq!(!Status(true), Status(false));
assert_eq!(!Status(false), Status(true));