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// Copyright 2020 Koichi Kitahara // // Licensed under either of Apache License, Version 2.0: // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // // or MIT license: // // Permission is hereby granted, free of charge, to any person obtaining a // copy of this software and associated documentation files (the "Software"), // to deal in the Software without restriction, including without limitation // the rights to use, copy, modify, merge, publish, distribute, sublicense, // and/or sell copies of the Software, and to permit persons to whom the // Software is furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in // all copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // DEALINGS IN THE SOFTWARE. // // at your option. #![cfg_attr(not(feature = "std"), no_std)] #![doc(html_root_url = "https://docs.rs/into-owned/0.3.0-alpha")] //! This crate provides a trait [`IntoOwned`] and three enums [`Is<'a, T>`], [`Gyu<'a, T>`], and [`GyuMut<'a, T>`]. //! //! [`IntoOwned`] associates a type with its owned variant. //! In this experimental version, [`IntoOwned`] is implemented only for primitive numeric types //! (`i8`, `i16`, `i32`, `i64`, `i128`, `isize`, `u8`, `u16`, `u32`, `u64`, `u128`, `usize`, `f32`, and `f64`) //! and their references. //! //! [`Is<'a, T>`], [`Gyu<'a, T>`], and [`GyuMut<'a, T>`] are clone-on-write smart pointers similar to [`Cow<'a, B>`]. //! These can be constructed from a type which is [`IntoOwned`]. //! See each documentation for more. //! //! [`IntoOwned`]: trait.IntoOwned.html //! [`Is<'a, T>`]: enum.Is.html //! [`Gyu<'a, T>`]: enum.Gyu.html //! [`GyuMut<'a, T>`]: enum.GyuMut.html //! [`Cow<'a, B>`]: https://doc.rust-lang.org/std/convert/trait.Cow.html mod gyu; mod gyu_mut; mod is; pub use gyu::Gyu; pub use gyu_mut::GyuMut; pub use is::Is; #[cfg(feature = "std")] use std::borrow::{Borrow, Cow}; /// A trait for associating a type with its owned variant. /// /// # Examples /// /// Implementing the `IntoOwned` trait for an owned type is straighitforward. /// Maybe a derive macro is supplied in future. /// ``` /// use into_owned::{IntoOwned, Is}; /// /// struct A(); /// /// impl IntoOwned for A { /// type Owned = Self; /// /// fn as_is<'a>(self) -> Is<'a, Self::Owned> { /// Is::Owned(self) /// } /// } /// ``` /// Since there are blanket implementations for `&T` and `&mut T` where /// `T: IntoOwned<Owned = T>`, /// manually implementing `IntoOwned` for the owned type is sufficient in most cases. pub trait IntoOwned where Self: Sized, { /// The owned type associated with `Self`. type Owned: Owned; /// Returns `self` as [`Is<'a, T>`] (`T` is `Self::Owned` here). /// /// This method is useful when `self` is used differently depending on /// its state: owned, (immutably) borrowed, or mutably borrowed. /// /// # Examples /// ``` /// use into_owned::{IntoOwned, Is}; /// /// // returns: /// // * `0` if `t` is an owned value /// // * `1` if `t` is an immutably borrowed reference /// // * `2` if `t` is a mutably borrowed reference /// fn a<T>(t: T) -> i8 /// where T: IntoOwned /// { /// match t.as_is() { /// Is::Owned(x) => { /// // here `x: T::Owned` /// 0 /// } /// Is::Borrowed(x) => { /// // here `x: &T::Owned` /// 1 /// } /// Is::MutBorrowed(x) => { /// // here `x: &mut T::Owned` /// 2 /// } /// } /// } /// /// assert_eq!(a(1.0), 0); /// assert_eq!(a(&1.0), 1); /// assert_eq!(a(&mut 1.0), 2); /// ``` /// /// In addition, [`Is<'a, T>`] has a functionality similar to [`Cow<'a, B>`]. /// See its documentation for more. /// /// [`Is<'a, T>`]: enum.Is.html /// [`Cow<'a, B>`]: https://doc.rust-lang.org/std/convert/trait.Cow.html fn as_is<'a>(self) -> Is<'a, Self::Owned> where Self: 'a; /// Converts `self` into an owned value. /// /// If `Self` and `Self::Owned` are the same, usually it just returns `self`. /// If not, usually it returns an owned value by cloning. /// /// This method requires `Self::Owned` to be `Clone`. fn into_owned(self) -> Self::Owned where Self::Owned: Clone, { match self.as_is() { Is::Owned(t) => t, Is::Borrowed(t) => t.clone(), Is::MutBorrowed(t) => t.clone(), } } /// Converts `self` into [`Gyu<'a, T>`] (`T` is `Self::Owned` here). /// /// [`Gyu<'a, T>`] has a functionality similar to [`Is<'a, T>`]. /// Unlike [`Is<'a, T>`], it cannot hold a mutably borrowed reference, /// and thus it is more similar to [`Cow<'a, B>`]. /// See its documentation for more. /// /// [`Is<'a, T>`]: enum.Is.html /// [`Gyu<'a, T>`]: enum.Gyu.html /// [`Cow<'a, B>`]: https://doc.rust-lang.org/std/convert/trait.Cow.html fn into_gyu<'a>(self) -> Gyu<'a, Self::Owned> where Self: 'a, { match self.as_is() { Is::Owned(t) => Gyu::Owned(t), Is::Borrowed(t) => Gyu::Borrowed(t), Is::MutBorrowed(t) => Gyu::Borrowed(&*t), } } /// Converts `self` into [`GyuMut<'a, T>`] (`T` is `Self::Owned` here) if possible, /// i.e., `self` is not an immutably borrowed reference. /// If [`GyuMut<'a, T>`] is necessary, use [`to_gyu_mut`] method instead. /// /// [`GyuMut<'a, T>`] has a functionality similar to [`Is<'a, T>`]. /// Unlike [`Is<'a, T>`], it cannot hold a immutably borrowed reference. /// [`GyuMut<'a, T>`] implements more traits which require mutablity. /// See its documentation for more. /// /// [`Is<'a, T>`]: enum.Is.html /// [`GyuMut<'a, T>`]: enum.GyuMut.html /// [`to_gyu_mut`]: #method.to_gyu_mut fn try_into_gyu_mut<'a>(self) -> Option<GyuMut<'a, Self::Owned>> where Self: 'a, { match self.as_is() { Is::Owned(t) => Some(GyuMut::Owned(t)), Is::Borrowed(_) => None, Is::MutBorrowed(t) => Some(GyuMut::MutBorrowed(t)), } } /// Converts `self` into [`GyuMut<'a, T>`] (`T` is `Self::Owned` here). /// Unlike [`try_into_gyu_mut`] method, /// it clones `self` if it is an immutably borrowed reference. /// /// [`try_into_gyu_mut`]: #method.try_into_gyu_mut /// [`GyuMut<'a, T>`]: enum.GyuMut.html fn to_gyu_mut<'a>(self) -> GyuMut<'a, Self::Owned> where Self: 'a, Self::Owned: Clone, { match self.as_is() { Is::Owned(t) => GyuMut::Owned(t), Is::Borrowed(t) => GyuMut::Owned(t.clone()), Is::MutBorrowed(t) => GyuMut::MutBorrowed(t), } } /// Converts `self` into [`Cow<'a, B>`]. /// /// This method is available if `std` feature is enabled (enabled by default). /// /// [`Cow<'a, B>`]: https://doc.rust-lang.org/std/convert/trait.Cow.html #[cfg(feature = "std")] fn into_cow<'a, B>(self) -> Cow<'a, B> where Self: 'a, Self::Owned: Borrow<B>, B: ToOwned<Owned = Self::Owned> + ?Sized, { match self.as_is() { Is::Owned(t) => Cow::Owned(t), Is::Borrowed(t) => Cow::Borrowed(t.borrow()), Is::MutBorrowed(t) => Cow::Borrowed((*t).borrow()), } } } impl<T> IntoOwned for &T where T: Owned, { type Owned = T; fn as_is<'a>(self) -> Is<'a, Self::Owned> where Self: 'a, { Is::Borrowed(self) } } impl<T> IntoOwned for &mut T where T: Owned, { type Owned = T; fn as_is<'a>(self) -> Is<'a, Self::Owned> where Self: 'a, { Is::MutBorrowed(self) } } macro_rules! impl_into_owned_for_owned_type { ($T: ty) => { impl IntoOwned for $T { type Owned = Self; fn as_is<'a>(self) -> Is<'a, Self::Owned> { Is::Owned(self) } } }; } impl_into_owned_for_owned_type!(i8); impl_into_owned_for_owned_type!(u8); impl_into_owned_for_owned_type!(i16); impl_into_owned_for_owned_type!(u16); impl_into_owned_for_owned_type!(i32); impl_into_owned_for_owned_type!(u32); impl_into_owned_for_owned_type!(i64); impl_into_owned_for_owned_type!(u64); impl_into_owned_for_owned_type!(isize); impl_into_owned_for_owned_type!(usize); impl_into_owned_for_owned_type!(i128); impl_into_owned_for_owned_type!(u128); impl_into_owned_for_owned_type!(f32); impl_into_owned_for_owned_type!(f64); /// A trait for an owned type. /// /// This trait is automatically implemented where `Self: `[`IntoOwned`]`<`[`Owned`]` = Self>`. /// /// [`IntoOwned`]: trait.IntoOwned.html /// [`Owned`]: trait.IntoOwned.html#associatedtype.Owned pub trait Owned where Self: IntoOwned<Owned = Self>, { } impl<T> Owned for T where Self: IntoOwned<Owned = Self> {}