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options.rs
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/
options.rs
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// SPDX-License-Identifier: MIT
// Copyright 2023 IROX Contributors
//!
//! `MaybeInto`, `MaybeFrom`, and `MaybeMap` - traits to improve chaining of optional functions and erasing `Result`s
//!
///
/// Like [`TryInto<T>`] but instead of returning a [`Result<Ok, Err>`] it returns simply an
/// [`Option<T>`]. Semantically identical to `Result<Ok, Err>.ok()`
pub trait MaybeInto<T> {
fn maybe_into(self) -> Option<T>;
}
///
/// Like [`TryFrom<T>`] but instead of returning a [`Result<Ok, Err>`] it returns simply an
/// [`Option<T>`]. Semantically identical to `Result<Ok, Err>.ok()`
pub trait MaybeFrom<T>: Sized {
fn maybe_from(value: T) -> Option<Self>;
}
impl<T, U> MaybeInto<U> for T
where
U: MaybeFrom<T>,
{
fn maybe_into(self) -> Option<U> {
U::maybe_from(self)
}
}
macro_rules! maybe_from_prim_str {
($type:ident) => {
impl MaybeFrom<Option<&str>> for $type {
fn maybe_from(value: Option<&str>) -> Option<$type> {
value?.parse().ok()
}
}
impl MaybeFrom<&str> for $type {
fn maybe_from(value: &str) -> Option<$type> {
value.parse().ok()
}
}
impl MaybeFrom<Option<$type>> for $type {
fn maybe_from(value: Option<$type>) -> Option<$type> {
value
}
}
};
}
maybe_from_prim_str!(u8);
maybe_from_prim_str!(i8);
maybe_from_prim_str!(u16);
maybe_from_prim_str!(i16);
maybe_from_prim_str!(u32);
maybe_from_prim_str!(i32);
maybe_from_prim_str!(u64);
maybe_from_prim_str!(i64);
maybe_from_prim_str!(u128);
maybe_from_prim_str!(i128);
maybe_from_prim_str!(f32);
maybe_from_prim_str!(f64);
maybe_from_prim_str!(char);
pub trait MaybeMap<Base, Out>: Sized {
fn maybe_map<R: FnOnce(Base) -> Option<Out>>(self, map: R) -> Option<Out>;
}
impl<Base, Out> MaybeMap<Base, Out> for Option<Base> {
fn maybe_map<R: FnOnce(Base) -> Option<Out>>(self, map: R) -> Option<Out> {
let Some(e) = self else {
return None;
};
map(e)
}
}