Move Try to module.
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Clar Charr
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@ -152,6 +152,7 @@
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mod function;
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mod place;
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mod range;
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mod try;
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#[stable(feature = "rust1", since = "1.0.0")]
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pub use self::arith::{Add, Sub, Mul, Div, Rem, Neg};
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@ -172,6 +173,12 @@
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#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
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pub use self::range::{RangeInclusive, RangeToInclusive};
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#[unstable(feature = "question_mark_carrier", issue = "31436")]
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#[cfg(stage0)]
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pub use self::try::Carrier;
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#[unstable(feature = "try_trait", issue = "42327")]
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pub use self::try::Try;
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#[unstable(feature = "placement_new_protocol", issue = "27779")]
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pub use self::place::{Place, Placer, InPlace, Boxed, BoxPlace};
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@ -593,105 +600,3 @@ impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *mut T {}
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// *const T -> *const U
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#[unstable(feature = "coerce_unsized", issue = "27732")]
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impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<*const U> for *const T {}
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/// This trait has been superseded by the `Try` trait, but must remain
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/// here as `?` is still lowered to it in stage0 .
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#[cfg(stage0)]
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#[unstable(feature = "question_mark_carrier", issue = "31436")]
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pub trait Carrier {
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/// The type of the value when computation succeeds.
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type Success;
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/// The type of the value when computation errors out.
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type Error;
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/// Create a `Carrier` from a success value.
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fn from_success(_: Self::Success) -> Self;
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/// Create a `Carrier` from an error value.
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fn from_error(_: Self::Error) -> Self;
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/// Translate this `Carrier` to another implementation of `Carrier` with the
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/// same associated types.
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fn translate<T>(self) -> T where T: Carrier<Success=Self::Success, Error=Self::Error>;
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}
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#[cfg(stage0)]
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#[unstable(feature = "question_mark_carrier", issue = "31436")]
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impl<U, V> Carrier for Result<U, V> {
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type Success = U;
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type Error = V;
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fn from_success(u: U) -> Result<U, V> {
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Ok(u)
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}
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fn from_error(e: V) -> Result<U, V> {
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Err(e)
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}
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fn translate<T>(self) -> T
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where T: Carrier<Success=U, Error=V>
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{
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match self {
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Ok(u) => T::from_success(u),
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Err(e) => T::from_error(e),
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}
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}
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}
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struct _DummyErrorType;
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impl Try for _DummyErrorType {
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type Ok = ();
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type Error = ();
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fn into_result(self) -> Result<Self::Ok, Self::Error> {
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Ok(())
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}
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fn from_ok(_: ()) -> _DummyErrorType {
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_DummyErrorType
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}
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fn from_error(_: ()) -> _DummyErrorType {
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_DummyErrorType
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}
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}
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/// A trait for customizing the behaviour of the `?` operator.
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///
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/// A type implementing `Try` is one that has a canonical way to view it
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/// in terms of a success/failure dichotomy. This trait allows both
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/// extracting those success or failure values from an existing instance and
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/// creating a new instance from a success or failure value.
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#[unstable(feature = "try_trait", issue = "42327")]
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pub trait Try {
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/// The type of this value when viewed as successful.
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#[unstable(feature = "try_trait", issue = "42327")]
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type Ok;
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/// The type of this value when viewed as failed.
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#[unstable(feature = "try_trait", issue = "42327")]
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type Error;
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/// Applies the "?" operator. A return of `Ok(t)` means that the
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/// execution should continue normally, and the result of `?` is the
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/// value `t`. A return of `Err(e)` means that execution should branch
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/// to the innermost enclosing `catch`, or return from the function.
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///
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/// If an `Err(e)` result is returned, the value `e` will be "wrapped"
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/// in the return type of the enclosing scope (which must itself implement
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/// `Try`). Specifically, the value `X::from_error(From::from(e))`
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/// is returned, where `X` is the return type of the enclosing function.
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#[unstable(feature = "try_trait", issue = "42327")]
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fn into_result(self) -> Result<Self::Ok, Self::Error>;
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/// Wrap an error value to construct the composite result. For example,
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/// `Result::Err(x)` and `Result::from_error(x)` are equivalent.
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#[unstable(feature = "try_trait", issue = "42327")]
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fn from_error(v: Self::Error) -> Self;
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/// Wrap an OK value to construct the composite result. For example,
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/// `Result::Ok(x)` and `Result::from_ok(x)` are equivalent.
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#[unstable(feature = "try_trait", issue = "42327")]
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fn from_ok(v: Self::Ok) -> Self;
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}
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111
src/libcore/ops/try.rs
Normal file
111
src/libcore/ops/try.rs
Normal file
@ -0,0 +1,111 @@
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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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/// This trait has been superseded by the `Try` trait, but must remain
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/// here as `?` is still lowered to it in stage0 .
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#[cfg(stage0)]
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#[unstable(feature = "question_mark_carrier", issue = "31436")]
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pub trait Carrier {
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/// The type of the value when computation succeeds.
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type Success;
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/// The type of the value when computation errors out.
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type Error;
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/// Create a `Carrier` from a success value.
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fn from_success(_: Self::Success) -> Self;
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/// Create a `Carrier` from an error value.
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fn from_error(_: Self::Error) -> Self;
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/// Translate this `Carrier` to another implementation of `Carrier` with the
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/// same associated types.
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fn translate<T>(self) -> T where T: Carrier<Success=Self::Success, Error=Self::Error>;
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}
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#[cfg(stage0)]
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#[unstable(feature = "question_mark_carrier", issue = "31436")]
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impl<U, V> Carrier for Result<U, V> {
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type Success = U;
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type Error = V;
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fn from_success(u: U) -> Result<U, V> {
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Ok(u)
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}
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fn from_error(e: V) -> Result<U, V> {
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Err(e)
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}
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fn translate<T>(self) -> T
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where T: Carrier<Success=U, Error=V>
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{
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match self {
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Ok(u) => T::from_success(u),
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Err(e) => T::from_error(e),
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}
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}
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}
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struct _DummyErrorType;
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impl Try for _DummyErrorType {
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type Ok = ();
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type Error = ();
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fn into_result(self) -> Result<Self::Ok, Self::Error> {
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Ok(())
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}
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fn from_ok(_: ()) -> _DummyErrorType {
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_DummyErrorType
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}
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fn from_error(_: ()) -> _DummyErrorType {
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_DummyErrorType
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}
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}
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/// A trait for customizing the behaviour of the `?` operator.
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///
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/// A type implementing `Try` is one that has a canonical way to view it
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/// in terms of a success/failure dichotomy. This trait allows both
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/// extracting those success or failure values from an existing instance and
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/// creating a new instance from a success or failure value.
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#[unstable(feature = "try_trait", issue = "42327")]
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pub trait Try {
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/// The type of this value when viewed as successful.
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#[unstable(feature = "try_trait", issue = "42327")]
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type Ok;
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/// The type of this value when viewed as failed.
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#[unstable(feature = "try_trait", issue = "42327")]
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type Error;
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/// Applies the "?" operator. A return of `Ok(t)` means that the
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/// execution should continue normally, and the result of `?` is the
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/// value `t`. A return of `Err(e)` means that execution should branch
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/// to the innermost enclosing `catch`, or return from the function.
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///
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/// If an `Err(e)` result is returned, the value `e` will be "wrapped"
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/// in the return type of the enclosing scope (which must itself implement
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/// `Try`). Specifically, the value `X::from_error(From::from(e))`
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/// is returned, where `X` is the return type of the enclosing function.
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#[unstable(feature = "try_trait", issue = "42327")]
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fn into_result(self) -> Result<Self::Ok, Self::Error>;
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/// Wrap an error value to construct the composite result. For example,
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/// `Result::Err(x)` and `Result::from_error(x)` are equivalent.
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#[unstable(feature = "try_trait", issue = "42327")]
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fn from_error(v: Self::Error) -> Self;
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/// Wrap an OK value to construct the composite result. For example,
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/// `Result::Ok(x)` and `Result::from_ok(x)` are equivalent.
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#[unstable(feature = "try_trait", issue = "42327")]
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fn from_ok(v: Self::Ok) -> Self;
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}
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