X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=library%2Fcore%2Fsrc%2Fops%2Fcontrol_flow.rs;h=ecaff053bd5c0ebe49471c176c3ade6b909fdc09;hb=587de8e5f9ef083b2546311f0c2c36bbad0ed8e3;hp=2f78ba8f28e29189697d5c78d375a792d13c3854;hpb=689978c17636415dbe4a2d87ac83b53cd2c42416;p=rust.git

diff --git a/library/core/src/ops/control_flow.rs b/library/core/src/ops/control_flow.rs
index 2f78ba8f28e..9d9398fb56d 100644
--- a/library/core/src/ops/control_flow.rs
+++ b/library/core/src/ops/control_flow.rs
@@ -1,4 +1,4 @@
-use crate::ops::Try;
+use crate::{convert, ops};
 
 /// Used to tell an operation whether it should exit early or go on as usual.
 ///
@@ -52,8 +52,10 @@
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum ControlFlow<B, C = ()> {
     /// Move on to the next phase of the operation as normal.
+    #[cfg_attr(not(bootstrap), lang = "Continue")]
     Continue(C),
     /// Exit the operation without running subsequent phases.
+    #[cfg_attr(not(bootstrap), lang = "Break")]
     Break(B),
     // Yes, the order of the variants doesn't match the type parameters.
     // They're in this order so that `ControlFlow<A, B>` <-> `Result<B, A>`
@@ -61,11 +63,12 @@ pub enum ControlFlow<B, C = ()> {
 }
 
 #[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
-impl<B, C> Try for ControlFlow<B, C> {
-    type Ok = C;
+#[cfg(bootstrap)]
+impl<B, C> ops::TryV1 for ControlFlow<B, C> {
+    type Output = C;
     type Error = B;
     #[inline]
-    fn into_result(self) -> Result<Self::Ok, Self::Error> {
+    fn into_result(self) -> Result<Self::Output, Self::Error> {
         match self {
             ControlFlow::Continue(y) => Ok(y),
             ControlFlow::Break(x) => Err(x),
@@ -76,11 +79,40 @@ fn from_error(v: Self::Error) -> Self {
         ControlFlow::Break(v)
     }
     #[inline]
-    fn from_ok(v: Self::Ok) -> Self {
+    fn from_ok(v: Self::Output) -> Self {
         ControlFlow::Continue(v)
     }
 }
 
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<B, C> ops::TryV2 for ControlFlow<B, C> {
+    type Output = C;
+    type Residual = ControlFlow<B, convert::Infallible>;
+
+    #[inline]
+    fn from_output(output: Self::Output) -> Self {
+        ControlFlow::Continue(output)
+    }
+
+    #[inline]
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            ControlFlow::Continue(c) => ControlFlow::Continue(c),
+            ControlFlow::Break(b) => ControlFlow::Break(ControlFlow::Break(b)),
+        }
+    }
+}
+
+#[unstable(feature = "try_trait_v2", issue = "84277")]
+impl<B, C> ops::FromResidual for ControlFlow<B, C> {
+    #[inline]
+    fn from_residual(residual: ControlFlow<B, convert::Infallible>) -> Self {
+        match residual {
+            ControlFlow::Break(b) => ControlFlow::Break(b),
+        }
+    }
+}
+
 impl<B, C> ControlFlow<B, C> {
     /// Returns `true` if this is a `Break` variant.
     ///
@@ -152,23 +184,46 @@ pub fn map_break<T, F>(self, f: F) -> ControlFlow<T, C>
     }
 }
 
-impl<R: Try> ControlFlow<R, R::Ok> {
+#[cfg(bootstrap)]
+impl<R: ops::TryV1> ControlFlow<R, R::Output> {
     /// Create a `ControlFlow` from any type implementing `Try`.
-    #[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
     #[inline]
-    pub fn from_try(r: R) -> Self {
-        match Try::into_result(r) {
+    pub(crate) fn from_try(r: R) -> Self {
+        match R::into_result(r) {
             Ok(v) => ControlFlow::Continue(v),
-            Err(v) => ControlFlow::Break(Try::from_error(v)),
+            Err(v) => ControlFlow::Break(R::from_error(v)),
+        }
+    }
+
+    /// Convert a `ControlFlow` into any type implementing `Try`;
+    #[inline]
+    pub(crate) fn into_try(self) -> R {
+        match self {
+            ControlFlow::Continue(v) => R::from_ok(v),
+            ControlFlow::Break(v) => v,
+        }
+    }
+}
+
+/// These are used only as part of implementing the iterator adapters.
+/// They have mediocre names and non-obvious semantics, so aren't
+/// currently on a path to potential stabilization.
+#[cfg(not(bootstrap))]
+impl<R: ops::TryV2> ControlFlow<R, R::Output> {
+    /// Create a `ControlFlow` from any type implementing `Try`.
+    #[inline]
+    pub(crate) fn from_try(r: R) -> Self {
+        match R::branch(r) {
+            ControlFlow::Continue(v) => ControlFlow::Continue(v),
+            ControlFlow::Break(v) => ControlFlow::Break(R::from_residual(v)),
         }
     }
 
     /// Convert a `ControlFlow` into any type implementing `Try`;
-    #[unstable(feature = "control_flow_enum", reason = "new API", issue = "75744")]
     #[inline]
-    pub fn into_try(self) -> R {
+    pub(crate) fn into_try(self) -> R {
         match self {
-            ControlFlow::Continue(v) => Try::from_ok(v),
+            ControlFlow::Continue(v) => R::from_output(v),
             ControlFlow::Break(v) => v,
         }
     }