74 lines
1.7 KiB
Rust
74 lines
1.7 KiB
Rust
#![doc(hidden)]
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/// Creates an enumeration and function for converting a representation into
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/// the enumeration type.
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///
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/// The syntax is similar to the `bitflags` macro, but each value has the
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/// syntax `value => enumeration`. `enum` is used instead of `struct`.
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///
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/// This will generate an `enum E` as well as a function `E::from_repr` which
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/// will return `Result<E, ReprError>`.
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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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$V:vis enum $E:ident: $T:ty
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{
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$($value:expr => $Enum:ident,)+
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}
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) => {
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$(#[$outer])*
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#[derive(Copy, Clone)]
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$V enum $E
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{
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$($Enum,)+
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}
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impl $E
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{
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/// Returns, if representable, the variant of `Self` from `n`.
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$V fn from_repr(n: $T) -> Result<Self, ReprError>
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{
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match n {
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$($value => Ok($E::$Enum),)+
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n => Err(ReprError::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::durandal::err::ReprError;
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c_enum! {
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#[derive(Debug, PartialEq)]
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enum TestEnum: u16
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{
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0 => Zero,
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1 => One,
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2 => Two,
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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::from_repr(0), Ok(TestEnum::Zero));
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assert_eq!(TestEnum::from_repr(1), Ok(TestEnum::One));
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assert_eq!(TestEnum::from_repr(2), Ok(TestEnum::Two));
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assert_eq!(TestEnum::from_repr(3), Err(ReprError::new(3)));
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assert_eq!(TestEnum::from_repr(4), Err(ReprError::new(4)));
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assert_eq!(TestEnum::from_repr(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::from_repr(3).unwrap();}
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}
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// EOF
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