//! custom operators are required, you should look toward macros or compiler
//! plugins to extend Rust's syntax.
//!
+//! Note that the `&&` and `||` operators short-circuit, i.e. they only
+//! evaluate their second operand if it contributes to the result. Since this
+//! behavior is not enforceable by traits, `&&` and `||` are not supported as
+//! overloadable operators.
+//!
//! Many of the operators take their operands by value. In non-generic
//! contexts involving built-in types, this is usually not a problem.
//! However, using these operators in generic code, requires some
//! ```
//!
//! See the documentation for each trait for an example implementation.
+//!
+//! The [`Fn`], [`FnMut`], and [`FnOnce`] traits are implemented by types that can be
+//! invoked like functions. Note that `Fn` takes `&self`, `FnMut` takes `&mut
+//! self` and `FnOnce` takes `self`. These correspond to the three kinds of
+//! methods that can be invoked on an instance: call-by-reference,
+//! call-by-mutable-reference, and call-by-value. The most common use of these
+//! traits is to act as bounds to higher-level functions that take functions or
+//! closures as arguments.
+//!
+//! [`Fn`]: trait.Fn.html
+//! [`FnMut`]: trait.FnMut.html
+//! [`FnOnce`]: trait.FnOnce.html
+//!
+//! Taking a `Fn` as a parameter:
+//!
+//! ```rust
+//! 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);
+//! ```
+//!
+//! Taking a `FnMut` as a parameter:
+//!
+//! ```rust
+//! 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);
+//! ```
+//!
+//! Taking a `FnOnce` as a parameter:
+//!
+//! ```rust
+//! 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
+//! ```
#![stable(feature = "rust1", since = "1.0.0")]
-use cmp::PartialOrd;
use fmt;
-use marker::{Sized, Unsize};
-use result::Result::{self, Ok, Err};
+use marker::Unsize;
/// The `Drop` trait is used to run some code when a value goes out of scope.
/// This is sometimes called a 'destructor'.
///
/// # Examples
///
-/// A trivial implementation of `Sub`. When `Foo - Foo` happens, it ends up
-/// calling `sub`, and therefore, `main` prints `Subtracting!`.
+/// This example creates a `Point` struct that implements the `Sub` trait, and
+/// then demonstrates subtracting two `Point`s.
///
/// ```
/// use std::ops::Sub;
///
-/// struct Foo;
+/// #[derive(Debug)]
+/// struct Point {
+/// x: i32,
+/// y: i32,
+/// }
///
-/// impl Sub for Foo {
-/// type Output = Foo;
+/// impl Sub for Point {
+/// type Output = Point;
///
-/// fn sub(self, _rhs: Foo) -> Foo {
-/// println!("Subtracting!");
-/// self
+/// fn sub(self, other: Point) -> Point {
+/// Point {
+/// x: self.x - other.x,
+/// y: self.y - other.y,
+/// }
+/// }
+/// }
+///
+/// impl PartialEq for Point {
+/// fn eq(&self, other: &Self) -> bool {
+/// self.x == other.x && self.y == other.y
/// }
/// }
///
/// fn main() {
-/// Foo - Foo;
+/// assert_eq!(Point { x: 3, y: 3 } - Point { x: 2, y: 3 },
+/// Point { x: 1, y: 0 });
/// }
/// ```
#[lang = "sub"]
///
/// # Examples
///
-/// A trivial implementation of `Div`. When `Foo / Foo` happens, it ends up
-/// calling `div`, and therefore, `main` prints `Dividing!`.
+/// Implementing a `Div`idable rational number struct:
///
/// ```
/// use std::ops::Div;
///
-/// struct Foo;
+/// // The uniqueness of rational numbers in lowest terms is a consequence of
+/// // the fundamental theorem of arithmetic.
+/// #[derive(Eq)]
+/// #[derive(PartialEq, Debug)]
+/// struct Rational {
+/// nominator: usize,
+/// denominator: usize,
+/// }
///
-/// impl Div for Foo {
-/// type Output = Foo;
+/// impl Rational {
+/// fn new(nominator: usize, denominator: usize) -> Self {
+/// if denominator == 0 {
+/// panic!("Zero is an invalid denominator!");
+/// }
///
-/// fn div(self, _rhs: Foo) -> Foo {
-/// println!("Dividing!");
-/// self
+/// // Reduce to lowest terms by dividing by the greatest common
+/// // divisor.
+/// let gcd = gcd(nominator, denominator);
+/// Rational {
+/// nominator: nominator / gcd,
+/// denominator: denominator / gcd,
+/// }
+/// }
+/// }
+///
+/// impl Div for Rational {
+/// // The division of rational numbers is a closed operation.
+/// type Output = Self;
+///
+/// fn div(self, rhs: Self) -> Self {
+/// if rhs.nominator == 0 {
+/// panic!("Cannot divide by zero-valued `Rational`!");
+/// }
+///
+/// let nominator = self.nominator * rhs.denominator;
+/// let denominator = self.denominator * rhs.nominator;
+/// Rational::new(nominator, denominator)
+/// }
+/// }
+///
+/// // Euclid's two-thousand-year-old algorithm for finding the greatest common
+/// // divisor.
+/// fn gcd(x: usize, y: usize) -> usize {
+/// let mut x = x;
+/// let mut y = y;
+/// while y != 0 {
+/// let t = y;
+/// y = x % y;
+/// x = t;
/// }
+/// x
/// }
///
/// fn main() {
-/// Foo / Foo;
+/// assert_eq!(Rational::new(1, 2), Rational::new(2, 4));
+/// assert_eq!(Rational::new(1, 2) / Rational::new(3, 4),
+/// Rational::new(2, 3));
/// }
/// ```
///
///
/// # Examples
///
-/// In this example, the `BitAnd` trait is implemented for a `BooleanVector`
-/// struct.
+/// In this example, the `&` operator is lifted to a trivial `Scalar` type.
///
/// ```
/// use std::ops::BitAnd;
///
-/// #[derive(Debug)]
-/// struct BooleanVector {
-/// value: Vec<bool>,
-/// };
+/// #[derive(Debug, PartialEq)]
+/// struct Scalar(bool);
///
-/// impl BitAnd for BooleanVector {
+/// impl BitAnd for Scalar {
/// type Output = Self;
///
+/// // rhs is the "right-hand side" of the expression `a & b`
/// fn bitand(self, rhs: Self) -> Self {
-/// BooleanVector {
-/// value: self.value
-/// .iter()
-/// .zip(rhs.value.iter())
-/// .map(|(x, y)| *x && *y)
-/// .collect(),
-/// }
+/// Scalar(self.0 & rhs.0)
/// }
/// }
///
-/// impl PartialEq for BooleanVector {
-/// fn eq(&self, other: &Self) -> bool {
-/// self.value == other.value
+/// fn main() {
+/// assert_eq!(Scalar(true) & Scalar(true), Scalar(true));
+/// assert_eq!(Scalar(true) & Scalar(false), Scalar(false));
+/// assert_eq!(Scalar(false) & Scalar(true), Scalar(false));
+/// assert_eq!(Scalar(false) & Scalar(false), Scalar(false));
+/// }
+/// ```
+///
+/// In this example, the `BitAnd` trait is implemented for a `BooleanVector`
+/// struct.
+///
+/// ```
+/// use std::ops::BitAnd;
+///
+/// #[derive(Debug, PartialEq)]
+/// struct BooleanVector(Vec<bool>);
+///
+/// impl BitAnd for BooleanVector {
+/// type Output = Self;
+///
+/// fn bitand(self, BooleanVector(rhs): Self) -> Self {
+/// let BooleanVector(lhs) = self;
+/// assert_eq!(lhs.len(), rhs.len());
+/// BooleanVector(lhs.iter().zip(rhs.iter()).map(|(x, y)| *x && *y).collect())
/// }
/// }
///
-/// let bv1 = BooleanVector { value: vec![true, true, false, false] };
-/// let bv2 = BooleanVector { value: vec![true, false, true, false] };
-/// let expected = BooleanVector { value: vec![true, false, false, false] };
-/// assert_eq!(bv1 & bv2, expected);
+/// fn main() {
+/// let bv1 = BooleanVector(vec![true, true, false, false]);
+/// let bv2 = BooleanVector(vec![true, false, true, false]);
+/// let expected = BooleanVector(vec![true, false, false, false]);
+/// assert_eq!(bv1 & bv2, expected);
+/// }
/// ```
#[lang = "bitand"]
#[stable(feature = "rust1", since = "1.0.0")]
///
/// # Examples
///
- /// A trivial implementation of `BitOr`. When `Foo | Foo` happens, it ends up
- /// calling `bitor`, and therefore, `main` prints `Bitwise Or-ing!`.
+ /// In this example, the `|` operator is lifted to a trivial `Scalar` type.
///
/// ```
/// use std::ops::BitOr;
///
- /// struct Foo;
+ /// #[derive(Debug, PartialEq)]
+ /// struct Scalar(bool);
+ ///
+ /// impl BitOr for Scalar {
+ /// type Output = Self;
+ ///
+ /// // rhs is the "right-hand side" of the expression `a | b`
+ /// fn bitor(self, rhs: Self) -> Self {
+ /// Scalar(self.0 | rhs.0)
+ /// }
+ /// }
+ ///
+ /// fn main() {
+ /// assert_eq!(Scalar(true) | Scalar(true), Scalar(true));
+ /// assert_eq!(Scalar(true) | Scalar(false), Scalar(true));
+ /// assert_eq!(Scalar(false) | Scalar(true), Scalar(true));
+ /// assert_eq!(Scalar(false) | Scalar(false), Scalar(false));
+ /// }
+ /// ```
+ ///
+ /// In this example, the `BitOr` trait is implemented for a `BooleanVector`
+ /// struct.
+ ///
+ /// ```
+ /// use std::ops::BitOr;
+ ///
+ /// #[derive(Debug, PartialEq)]
+ /// struct BooleanVector(Vec<bool>);
///
- /// impl BitOr for Foo {
- /// type Output = Foo;
+ /// impl BitOr for BooleanVector {
+ /// type Output = Self;
///
- /// fn bitor(self, _rhs: Foo) -> Foo {
- /// println!("Bitwise Or-ing!");
- /// self
+ /// fn bitor(self, BooleanVector(rhs): Self) -> Self {
+ /// let BooleanVector(lhs) = self;
+ /// assert_eq!(lhs.len(), rhs.len());
+ /// BooleanVector(lhs.iter().zip(rhs.iter()).map(|(x, y)| *x || *y).collect())
/// }
/// }
///
/// fn main() {
- /// Foo | Foo;
+ /// let bv1 = BooleanVector(vec![true, true, false, false]);
+ /// let bv2 = BooleanVector(vec![true, false, true, false]);
+ /// let expected = BooleanVector(vec![true, true, true, false]);
+ /// assert_eq!(bv1 | bv2, expected);
/// }
/// ```
#[lang = "bitor"]
///
/// # Examples
///
- /// A trivial implementation of `BitXor`. When `Foo ^ Foo` happens, it ends up
- /// calling `bitxor`, and therefore, `main` prints `Bitwise Xor-ing!`.
+ /// In this example, the `^` operator is lifted to a trivial `Scalar` type.
///
/// ```
/// use std::ops::BitXor;
///
- /// struct Foo;
+ /// #[derive(Debug, PartialEq)]
+ /// struct Scalar(bool);
+ ///
+ /// impl BitXor for Scalar {
+ /// type Output = Self;
+ ///
+ /// // rhs is the "right-hand side" of the expression `a ^ b`
+ /// fn bitxor(self, rhs: Self) -> Self {
+ /// Scalar(self.0 ^ rhs.0)
+ /// }
+ /// }
+ ///
+ /// fn main() {
+ /// assert_eq!(Scalar(true) ^ Scalar(true), Scalar(false));
+ /// assert_eq!(Scalar(true) ^ Scalar(false), Scalar(true));
+ /// assert_eq!(Scalar(false) ^ Scalar(true), Scalar(true));
+ /// assert_eq!(Scalar(false) ^ Scalar(false), Scalar(false));
+ /// }
+ /// ```
+ ///
+ /// In this example, the `BitXor` trait is implemented for a `BooleanVector`
+ /// struct.
+ ///
+ /// ```
+ /// use std::ops::BitXor;
+ ///
+ /// #[derive(Debug, PartialEq)]
+ /// struct BooleanVector(Vec<bool>);
///
- /// impl BitXor for Foo {
- /// type Output = Foo;
+ /// impl BitXor for BooleanVector {
+ /// type Output = Self;
///
- /// fn bitxor(self, _rhs: Foo) -> Foo {
- /// println!("Bitwise Xor-ing!");
- /// self
+ /// fn bitxor(self, BooleanVector(rhs): Self) -> Self {
+ /// let BooleanVector(lhs) = self;
+ /// assert_eq!(lhs.len(), rhs.len());
+ /// BooleanVector(lhs.iter()
+ /// .zip(rhs.iter())
+ /// .map(|(x, y)| (*x || *y) && !(*x && *y))
+ /// .collect())
/// }
/// }
///
/// fn main() {
- /// Foo ^ Foo;
+ /// let bv1 = BooleanVector(vec![true, true, false, false]);
+ /// let bv2 = BooleanVector(vec![true, false, true, false]);
+ /// let expected = BooleanVector(vec![false, true, true, false]);
+ /// assert_eq!(bv1 ^ bv2, expected);
/// }
/// ```
#[lang = "bitxor"]
///
/// # Examples
///
-/// A trivial implementation of `Shl`. When `Foo << Foo` happens, it ends up
-/// calling `shl`, and therefore, `main` prints `Shifting left!`.
+/// An implementation of `Shl` that lifts the `<<` operation on integers to a
+/// `Scalar` struct.
///
/// ```
/// use std::ops::Shl;
///
-/// struct Foo;
+/// #[derive(PartialEq, Debug)]
+/// struct Scalar(usize);
///
-/// impl Shl<Foo> for Foo {
-/// type Output = Foo;
+/// impl Shl<Scalar> for Scalar {
+/// type Output = Self;
///
-/// fn shl(self, _rhs: Foo) -> Foo {
-/// println!("Shifting left!");
-/// self
+/// fn shl(self, Scalar(rhs): Self) -> Scalar {
+/// let Scalar(lhs) = self;
+/// Scalar(lhs << rhs)
+/// }
+/// }
+/// fn main() {
+/// assert_eq!(Scalar(4) << Scalar(2), Scalar(16));
+/// }
+/// ```
+///
+/// An implementation of `Shl` that spins a vector leftward by a given amount.
+///
+/// ```
+/// use std::ops::Shl;
+///
+/// #[derive(PartialEq, Debug)]
+/// struct SpinVector<T: Clone> {
+/// vec: Vec<T>,
+/// }
+///
+/// impl<T: Clone> Shl<usize> for SpinVector<T> {
+/// type Output = Self;
+///
+/// fn shl(self, rhs: usize) -> SpinVector<T> {
+/// // rotate the vector by `rhs` places
+/// let (a, b) = self.vec.split_at(rhs);
+/// let mut spun_vector: Vec<T> = vec![];
+/// spun_vector.extend_from_slice(b);
+/// spun_vector.extend_from_slice(a);
+/// SpinVector { vec: spun_vector }
/// }
/// }
///
/// fn main() {
-/// Foo << Foo;
+/// assert_eq!(SpinVector { vec: vec![0, 1, 2, 3, 4] } << 2,
+/// SpinVector { vec: vec![2, 3, 4, 0, 1] });
/// }
/// ```
#[lang = "shl"]
///
/// # Examples
///
-/// A trivial implementation of `Shr`. When `Foo >> Foo` happens, it ends up
-/// calling `shr`, and therefore, `main` prints `Shifting right!`.
+/// An implementation of `Shr` that lifts the `>>` operation on integers to a
+/// `Scalar` struct.
///
/// ```
/// use std::ops::Shr;
///
-/// struct Foo;
+/// #[derive(PartialEq, Debug)]
+/// struct Scalar(usize);
///
-/// impl Shr<Foo> for Foo {
-/// type Output = Foo;
+/// impl Shr<Scalar> for Scalar {
+/// type Output = Self;
///
-/// fn shr(self, _rhs: Foo) -> Foo {
-/// println!("Shifting right!");
-/// self
+/// fn shr(self, Scalar(rhs): Self) -> Scalar {
+/// let Scalar(lhs) = self;
+/// Scalar(lhs >> rhs)
+/// }
+/// }
+/// fn main() {
+/// assert_eq!(Scalar(16) >> Scalar(2), Scalar(4));
+/// }
+/// ```
+///
+/// An implementation of `Shr` that spins a vector rightward by a given amount.
+///
+/// ```
+/// use std::ops::Shr;
+///
+/// #[derive(PartialEq, Debug)]
+/// struct SpinVector<T: Clone> {
+/// vec: Vec<T>,
+/// }
+///
+/// impl<T: Clone> Shr<usize> for SpinVector<T> {
+/// type Output = Self;
+///
+/// fn shr(self, rhs: usize) -> SpinVector<T> {
+/// // rotate the vector by `rhs` places
+/// let (a, b) = self.vec.split_at(self.vec.len() - rhs);
+/// let mut spun_vector: Vec<T> = vec![];
+/// spun_vector.extend_from_slice(b);
+/// spun_vector.extend_from_slice(a);
+/// SpinVector { vec: spun_vector }
/// }
/// }
///
/// fn main() {
-/// Foo >> Foo;
+/// assert_eq!(SpinVector { vec: vec![0, 1, 2, 3, 4] } >> 2,
+/// SpinVector { vec: vec![3, 4, 0, 1, 2] });
/// }
/// ```
#[lang = "shr"]
///
/// # Examples
///
-/// A trivial implementation of `SubAssign`. When `Foo -= Foo` happens, it ends up
-/// calling `sub_assign`, and therefore, `main` prints `Subtracting!`.
+/// This example creates a `Point` struct that implements the `SubAssign`
+/// trait, and then demonstrates sub-assigning to a mutable `Point`.
///
/// ```
/// use std::ops::SubAssign;
///
-/// struct Foo;
+/// #[derive(Debug)]
+/// struct Point {
+/// x: i32,
+/// y: i32,
+/// }
///
-/// impl SubAssign for Foo {
-/// fn sub_assign(&mut self, _rhs: Foo) {
-/// println!("Subtracting!");
+/// impl SubAssign for Point {
+/// fn sub_assign(&mut self, other: Point) {
+/// *self = Point {
+/// x: self.x - other.x,
+/// y: self.y - other.y,
+/// };
/// }
/// }
///
-/// # #[allow(unused_assignments)]
-/// fn main() {
-/// let mut foo = Foo;
-/// foo -= Foo;
+/// impl PartialEq for Point {
+/// fn eq(&self, other: &Self) -> bool {
+/// self.x == other.x && self.y == other.y
+/// }
/// }
+///
+/// let mut point = Point { x: 3, y: 3 };
+/// point -= Point { x: 2, y: 3 };
+/// assert_eq!(point, Point {x: 1, y: 0});
/// ```
#[lang = "sub_assign"]
#[stable(feature = "op_assign_traits", since = "1.8.0")]
///
/// It cannot serve as an iterator because it doesn't have a starting point.
///
+/// # Examples
+///
+/// The `..{integer}` syntax is a `RangeTo`:
+///
+/// ```
+/// assert_eq!((..5), std::ops::RangeTo{ end: 5 });
/// ```
-/// fn main() {
-/// assert_eq!((..5), std::ops::RangeTo{ end: 5 });
///
-/// let arr = [0, 1, 2, 3];
-/// assert_eq!(arr[ .. ], [0,1,2,3]);
-/// assert_eq!(arr[ ..3], [0,1,2 ]); // RangeTo
-/// assert_eq!(arr[1.. ], [ 1,2,3]);
-/// assert_eq!(arr[1..3], [ 1,2 ]);
+/// It does not have an `IntoIterator` implementation, so you can't use it in a
+/// `for` loop directly. This won't compile:
+///
+/// ```ignore
+/// for i in ..5 {
+/// // ...
/// }
/// ```
+///
+/// When used as a slicing index, `RangeTo` produces a slice of all array
+/// elements before the index indicated by `end`.
+///
+/// ```
+/// let arr = [0, 1, 2, 3];
+/// assert_eq!(arr[ .. ], [0,1,2,3]);
+/// assert_eq!(arr[ ..3], [0,1,2 ]); // RangeTo
+/// assert_eq!(arr[1.. ], [ 1,2,3]);
+/// assert_eq!(arr[1..3], [ 1,2 ]);
+/// ```
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RangeTo<Idx> {
///
/// # Examples
///
+/// The `...{integer}` syntax is a `RangeToInclusive`:
+///
/// ```
/// #![feature(inclusive_range,inclusive_range_syntax)]
-/// fn main() {
-/// assert_eq!((...5), std::ops::RangeToInclusive{ end: 5 });
+/// assert_eq!((...5), std::ops::RangeToInclusive{ end: 5 });
+/// ```
///
-/// let arr = [0, 1, 2, 3];
-/// assert_eq!(arr[ ...2], [0,1,2 ]); // RangeToInclusive
-/// assert_eq!(arr[1...2], [ 1,2 ]);
+/// It does not have an `IntoIterator` implementation, so you can't use it in a
+/// `for` loop directly. This won't compile:
+///
+/// ```ignore
+/// for i in ...5 {
+/// // ...
/// }
/// ```
+///
+/// When used as a slicing index, `RangeToInclusive` produces a slice of all
+/// array elements up to and including the index indicated by `end`.
+///
+/// ```
+/// #![feature(inclusive_range_syntax)]
+/// let arr = [0, 1, 2, 3];
+/// assert_eq!(arr[ ...2], [0,1,2 ]); // RangeToInclusive
+/// assert_eq!(arr[1...2], [ 1,2 ]);
+/// ```
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
#[unstable(feature = "inclusive_range", reason = "recently added, follows RFC", issue = "28237")]
pub struct RangeToInclusive<Idx> {
}
/// 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]
}
/// 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]
}
/// 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]
}
mod impls {
- use marker::Sized;
- use super::{Fn, FnMut, FnOnce};
-
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a,A,F:?Sized> Fn<A> for &'a F
where F : Fn<A>
projects / rust.git / commitdiff