Move more stuff out of markers.

Author: Clar Charr

src/libcore/ops/fn.rs

@@ -0,0 +1,186 @@
+/// A version of the call operator that takes an immutable receiver.
+///
+/// # Examples
+///
+/// Closures automatically implement this trait, which allows them to be
+/// invoked. Note, however, that `Fn` takes an immutable reference to any
+/// captured variables. To take a mutable capture, implement [`FnMut`], and to
+/// consume the capture, implement [`FnOnce`].
+///
+/// [`FnMut`]: trait.FnMut.html
+/// [`FnOnce`]: trait.FnOnce.html
+///
+/// ```
+/// let square = |x| x * x;
+/// assert_eq!(square(5), 25);
+/// ```
+///
+/// Closures can also be passed to higher-level functions through a `Fn`
+/// parameter (or a `FnMut` or `FnOnce` parameter, which are supertraits of
+/// `Fn`).
+///
+/// ```
+/// fn call_with_one<F>(func: F) -> usize
+///     where F: Fn(usize) -> usize {
+///     func(1)
+/// }
+///
+/// let double = |x| x * 2;
+/// assert_eq!(call_with_one(double), 2);
+/// ```
+#[lang = "fn"]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_paren_sugar]
+#[fundamental] // so that regex can rely that `&str: !FnMut`
+pub trait Fn<Args> : FnMut<Args> {
+    /// This is called when the call operator is used.
+    #[unstable(feature = "fn_traits", issue = "29625")]
+    extern "rust-call" fn call(&self, args: Args) -> Self::Output;
+}
+
+/// A version of the call operator that takes a mutable receiver.
+///
+/// # Examples
+///
+/// Closures that mutably capture variables automatically implement this trait,
+/// which allows them to be invoked.
+///
+/// ```
+/// let mut x = 5;
+/// {
+///     let mut square_x = || x *= x;
+///     square_x();
+/// }
+/// assert_eq!(x, 25);
+/// ```
+///
+/// Closures can also be passed to higher-level functions through a `FnMut`
+/// parameter (or a `FnOnce` parameter, which is a supertrait of `FnMut`).
+///
+/// ```
+/// fn do_twice<F>(mut func: F)
+///     where F: FnMut()
+/// {
+///     func();
+///     func();
+/// }
+///
+/// let mut x: usize = 1;
+/// {
+///     let add_two_to_x = || x += 2;
+///     do_twice(add_two_to_x);
+/// }
+///
+/// assert_eq!(x, 5);
+/// ```
+#[lang = "fn_mut"]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_paren_sugar]
+#[fundamental] // so that regex can rely that `&str: !FnMut`
+pub trait FnMut<Args> : FnOnce<Args> {
+    /// This is called when the call operator is used.
+    #[unstable(feature = "fn_traits", issue = "29625")]
+    extern "rust-call" fn call_mut(&mut self, args: Args) -> Self::Output;
+}
+
+/// A version of the call operator that takes a by-value receiver.
+///
+/// # Examples
+///
+/// By-value closures automatically implement this trait, which allows them to
+/// be invoked.
+///
+/// ```
+/// let x = 5;
+/// let square_x = move || x * x;
+/// assert_eq!(square_x(), 25);
+/// ```
+///
+/// By-value Closures can also be passed to higher-level functions through a
+/// `FnOnce` parameter.
+///
+/// ```
+/// fn consume_with_relish<F>(func: F)
+///     where F: FnOnce() -> String
+/// {
+///     // `func` consumes its captured variables, so it cannot be run more
+///     // than once
+///     println!("Consumed: {}", func());
+///
+///     println!("Delicious!");
+///
+///     // Attempting to invoke `func()` again will throw a `use of moved
+///     // value` error for `func`
+/// }
+///
+/// let x = String::from("x");
+/// let consume_and_return_x = move || x;
+/// consume_with_relish(consume_and_return_x);
+///
+/// // `consume_and_return_x` can no longer be invoked at this point
+/// ```
+#[lang = "fn_once"]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[rustc_paren_sugar]
+#[fundamental] // so that regex can rely that `&str: !FnMut`
+pub trait FnOnce<Args> {
+    /// The returned type after the call operator is used.
+    #[stable(feature = "fn_once_output", since = "1.12.0")]
+    type Output;
+
+    /// This is called when the call operator is used.
+    #[unstable(feature = "fn_traits", issue = "29625")]
+    extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
+}
+
+mod impls {
+    #[stable(feature = "rust1", since = "1.0.0")]
+    impl<'a,A,F:?Sized> Fn<A> for &'a F
+        where F : Fn<A>
+    {
+        extern "rust-call" fn call(&self, args: A) -> F::Output {
+            (**self).call(args)
+        }
+    }
+
+    #[stable(feature = "rust1", since = "1.0.0")]
+    impl<'a,A,F:?Sized> FnMut<A> for &'a F
+        where F : Fn<A>
+    {
+        extern "rust-call" fn call_mut(&mut self, args: A) -> F::Output {
+            (**self).call(args)
+        }
+    }
+
+    #[stable(feature = "rust1", since = "1.0.0")]
+    impl<'a,A,F:?Sized> FnOnce<A> for &'a F
+        where F : Fn<A>
+    {
+        type Output = F::Output;
+
+        extern "rust-call" fn call_once(self, args: A) -> F::Output {
+            (*self).call(args)
+        }
+    }
+
+    #[stable(feature = "rust1", since = "1.0.0")]
+    impl<'a,A,F:?Sized> FnMut<A> for &'a mut F
+        where F : FnMut<A>
+    {
+        extern "rust-call" fn call_mut(&mut self, args: A) -> F::Output {
+            (*self).call_mut(args)
+        }
+    }
+
+    #[stable(feature = "rust1", since = "1.0.0")]
+    impl<'a,A,F:?Sized> FnOnce<A> for &'a mut F
+        where F : FnMut<A>
+    {
+        type Output = F::Output;
+        extern "rust-call" fn call_once(mut self, args: A) -> F::Output {
+            (*self).call_mut(args)
+        }
+    }
+}
+
+