101 lines
2.5 KiB
Rust
101 lines
2.5 KiB
Rust
#![doc(hidden)]
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/// Creates an enumeration and function for converting a representation into the
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/// enumeration type.
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///
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/// The syntax is similar to the `bitflags` macro, but each value has the syntax
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/// `value = enumeration`. `enum` is used instead of `struct`.
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///
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/// This will generate an `enum $t` as well as implement `TryFrom` on it which
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/// will return `Result<$t, ReprError>`.
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///
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/// # Examples
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///
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/// ```
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/// use maraiah::{c_enum, err::ReprError};
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/// use std::convert::TryFrom;
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///
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/// c_enum! {
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/// enum MyEnum: u16
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/// {
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/// Zero = 0,
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/// One = 1,
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/// Two = 2
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/// }
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/// }
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///
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/// assert_eq!(MyEnum::try_from(0), Ok(MyEnum::Zero));
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/// assert_eq!(MyEnum::try_from(1), Ok(MyEnum::One));
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/// assert_eq!(MyEnum::try_from(2), Ok(MyEnum::Two));
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/// assert_eq!(MyEnum::try_from(3), Err(ReprError::new(3)));
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/// assert_eq!(MyEnum::try_from(4), Err(ReprError::new(4)));
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/// assert_eq!(MyEnum::try_from(5), Err(ReprError::new(5)));
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/// ```
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#[macro_export]
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macro_rules! c_enum
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{
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(
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$(#[$outer:meta])*
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$vi:vis enum $t:ident: $ti:ident
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{
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$($(#[$vouter:meta])* $en:ident = $va:expr),+ $(,)?
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}
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) => {
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$(#[$outer])*
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#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
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#[repr($ti)]
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$vi enum $t
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{
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$($(#[$vouter])* $en = $va,)+
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}
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#[allow(unused_qualifications)]
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impl std::convert::TryFrom<$ti> for $t
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{
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type Error = $crate::err::ReprError;
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/// Returns, if representable, the variant of `Self` from `n`.
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fn try_from(n: $ti) -> Result<Self, Self::Error>
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{
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match n {
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$($va => Ok($t::$en),)+
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n => Err(Self::Error::new(n))
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}
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}
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}
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};
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}
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#[cfg(test)]
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mod test
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{
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use crate::err::ReprError;
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use std::convert::TryFrom;
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c_enum! {
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enum TestEnum: u16
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{
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Zero = 0,
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One = 1,
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Two = 2,
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}
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}
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#[test]
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fn c_enum_should_be_ok()
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{
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assert_eq!(TestEnum::try_from(0), Ok(TestEnum::Zero));
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assert_eq!(TestEnum::try_from(1), Ok(TestEnum::One));
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assert_eq!(TestEnum::try_from(2), Ok(TestEnum::Two));
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assert_eq!(TestEnum::try_from(3), Err(ReprError::new(3)));
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assert_eq!(TestEnum::try_from(4), Err(ReprError::new(4)));
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assert_eq!(TestEnum::try_from(5), Err(ReprError::new(5)));
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}
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#[test]
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#[should_panic]
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fn c_enum_should_error() {TestEnum::try_from(3).unwrap();}
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}
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// EOF
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