# Struct std::cmp::Reverse

1.19.0 · source ·

    #[repr(transparent)]pub struct Reverse<T>(pub T);

Expand description

A helper struct for reverse ordering.

This struct is a helper to be used with functions like `Vec::sort_by_key` and can be used to reverse order a part of a key.

## Examples

    use std::cmp::Reverse;

    let mut v = vec![1, 2, 3, 4, 5, 6];
    v.sort_by_key(|&num| (num > 3, Reverse(num)));
    assert_eq!(v, vec![3, 2, 1, 6, 5, 4]);

Run

## Tuple Fields§

§`0: T`

## Trait Implementations§

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### impl<T> Clone for Reverse<T>where T: Clone,

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#### fn clone(&self) -> Reverse<T>

Returns a copy of the value. Read more
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#### fn clone_from(&mut self, other: &Reverse<T>)

Performs copy-assignment from `source`. Read more
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### impl<T> Debug for Reverse<T>where T: Debug,

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter. Read more
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### impl<T> Default for Reverse<T>where T: Default,

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#### fn default() -> Reverse<T>

Returns the “default value” for a type. Read more
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### impl<T> Hash for Reverse<T>where T: Hash,

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#### fn hash<__H>(&self, state: &mut __H)where __H: Hasher,

Feeds this value into the given `Hasher`. Read more
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#### fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given `Hasher`. Read more
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### impl<T> Ord for Reverse<T>where T: Ord,

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#### fn cmp(&self, other: &Reverse<T>) -> Ordering

This method returns an `Ordering` between `self` and `other`. Read more
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#### fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values. Read more
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#### fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values. Read more
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#### fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd,

Restrict a value to a certain interval. Read more
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### impl<T> PartialEq for Reverse<T>where T: PartialEq,

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#### fn eq(&self, other: &Reverse<T>) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`.
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#### fn ne(&self, other: &Rhs) -> bool

This method tests for `!=`. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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### impl<T> PartialOrd for Reverse<T>where T: PartialOrd,

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#### fn partial_cmp(&self, other: &Reverse<T>) -> Option<Ordering>

This method returns an ordering between `self` and `other` values if one exists. Read more
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#### fn lt(&self, other: &Reverse<T>) -> bool

This method tests less than (for `self` and `other`) and is used by the `<` operator. Read more
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#### fn le(&self, other: &Reverse<T>) -> bool

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator. Read more
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#### fn gt(&self, other: &Reverse<T>) -> bool

This method tests greater than (for `self` and `other`) and is used by the `>` operator. Read more
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#### fn ge(&self, other: &Reverse<T>) -> bool

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator. Read more
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### impl<T> Copy for Reverse<T>where T: Copy,

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### impl<T> Eq for Reverse<T>where T: Eq,

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### impl<T> StructuralEq for Reverse<T>

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### impl<T> StructuralPartialEq for Reverse<T>

## Auto Trait Implementations§

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### impl<T> RefUnwindSafe for Reverse<T>where T: RefUnwindSafe,

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### impl<T> Send for Reverse<T>where T: Send,

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### impl<T> Sync for Reverse<T>where T: Sync,

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### impl<T> Unpin for Reverse<T>where T: Unpin,

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### impl<T> UnwindSafe for Reverse<T>where T: UnwindSafe,

## Blanket Implementations§

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### impl<T> Any for Twhere T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for Twhere T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for Twhere T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for Twhere U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> ToOwned for Twhere T: Clone,

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#### type Owned = T

The resulting type after obtaining ownership.
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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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#### fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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### impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.