94 lines
1.9 KiB
Rust
94 lines
1.9 KiB
Rust
mod result;
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pub use result::{_Err, _Ok};
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mod option;
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pub use option::{_None, _Some};
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/// Wrapper type
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#[derive(Clone, Copy)]
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#[repr(transparent)]
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pub struct Prism<P>(pub(crate) P);
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pub trait PrismPreview<T> {
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type Field;
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fn preview(thing: T) -> Option<Self::Field>;
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}
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pub trait PrismReview<T>: PrismPreview<T> {
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fn review(thing: Self::Field) -> T;
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}
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impl<P, T> PrismPreview<T> for Prism<P>
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where
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P: PrismPreview<T>,
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{
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type Field = P::Field;
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fn preview(thing: T) -> Option<Self::Field> {
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P::preview(thing)
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}
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}
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impl<P, T> PrismReview<T> for Prism<P>
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where
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P: PrismReview<T>,
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{
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fn review(thing: Self::Field) -> T {
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P::review(thing)
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}
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}
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pub fn preview<T, P: PrismPreview<T>>(_prism: P, thing: T) -> Option<P::Field> {
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P::preview(thing)
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}
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pub fn review<T, P: PrismReview<T>>(_prism: P, thing: P::Field) -> T {
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P::review(thing)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn preview_result() {
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let a: Result<i32, i32> = Ok(3);
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assert_eq!(preview(_Ok, a), Some(3));
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let a: Result<i32, i32> = Err(3);
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assert_eq!(preview(_Ok, a), None);
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let a: Result<i32, i32> = Ok(3);
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assert_eq!(preview(_Err, a), None);
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let a: Result<i32, i32> = Err(3);
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assert_eq!(preview(_Err, a), Some(3));
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}
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#[test]
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fn preview_option() {
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let a = Some(3);
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assert_eq!(preview(_Some, a), Some(3));
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let a = Some(3);
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assert_eq!(preview(_None, a), Some(()));
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let a: Option<i32> = None;
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assert_eq!(preview(_Some, a), None);
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let a: Option<i32> = None;
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assert_eq!(preview(_None, a), Some(()));
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}
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#[test]
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fn review_result() {
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assert_eq!(review(_Ok, 3), Ok::<i32, i32>(3));
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assert_eq!(review(_Err, 3), Err::<i32, i32>(3));
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}
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#[test]
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fn review_option() {
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assert_eq!(review(_Some, 3), Some(3));
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assert_eq!(review(_None, ()), None::<()>);
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}
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}
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