1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Functionality for ordering and comparison.
13 //! This module defines both [`PartialOrd`] and [`PartialEq`] traits which are used
14 //! by the compiler to implement comparison operators. Rust programs may
15 //! implement [`PartialOrd`] to overload the `<`, `<=`, `>`, and `>=` operators,
16 //! and may implement [`PartialEq`] to overload the `==` and `!=` operators.
18 //! [`PartialOrd`]: trait.PartialOrd.html
19 //! [`PartialEq`]: trait.PartialEq.html
27 //! // these two lines are equivalent
28 //! assert_eq!(x < y, true);
29 //! assert_eq!(x.lt(&y), true);
31 //! // these two lines are also equivalent
32 //! assert_eq!(x == y, false);
33 //! assert_eq!(x.eq(&y), false);
36 #![stable(feature = "rust1", since = "1.0.0")]
38 use self::Ordering::*;
40 /// Trait for equality comparisons which are [partial equivalence
41 /// relations](http://en.wikipedia.org/wiki/Partial_equivalence_relation).
43 /// This trait allows for partial equality, for types that do not have a full
44 /// equivalence relation. For example, in floating point numbers `NaN != NaN`,
45 /// so floating point types implement `PartialEq` but not `Eq`.
47 /// Formally, the equality must be (for all `a`, `b` and `c`):
49 /// - symmetric: `a == b` implies `b == a`; and
50 /// - transitive: `a == b` and `b == c` implies `a == c`.
52 /// Note that these requirements mean that the trait itself must be implemented
53 /// symmetrically and transitively: if `T: PartialEq<U>` and `U: PartialEq<V>`
54 /// then `U: PartialEq<T>` and `T: PartialEq<V>`.
58 /// This trait can be used with `#[derive]`. When `derive`d on structs, two
59 /// instances are equal if all fields are equal, and not equal if any fields
60 /// are not equal. When `derive`d on enums, each variant is equal to itself
61 /// and not equal to the other variants.
63 /// ## How can I implement `PartialEq`?
65 /// PartialEq only requires the `eq` method to be implemented; `ne` is defined
66 /// in terms of it by default. Any manual implementation of `ne` *must* respect
67 /// the rule that `eq` is a strict inverse of `ne`; that is, `!(a == b)` if and
70 /// Implementations of `PartialEq`, `PartialOrd`, and `Ord` *must* agree with
71 /// each other. It's easy to accidentally make them disagree by deriving some
72 /// of the traits and manually implementing others.
74 /// An example implementation for a domain in which two books are considered
75 /// the same book if their ISBN matches, even if the formats differ:
78 /// enum BookFormat { Paperback, Hardback, Ebook }
81 /// format: BookFormat,
84 /// impl PartialEq for Book {
85 /// fn eq(&self, other: &Book) -> bool {
86 /// self.isbn == other.isbn
90 /// let b1 = Book { isbn: 3, format: BookFormat::Paperback };
91 /// let b2 = Book { isbn: 3, format: BookFormat::Ebook };
92 /// let b3 = Book { isbn: 10, format: BookFormat::Paperback };
94 /// assert!(b1 == b2);
95 /// assert!(b1 != b3);
104 /// assert_eq!(x == y, false);
105 /// assert_eq!(x.eq(&y), false);
108 #[stable(feature = "rust1", since = "1.0.0")]
109 #[rustc_on_unimplemented = "can't compare `{Self}` with `{Rhs}`"]
110 pub trait PartialEq<Rhs: ?Sized = Self> {
111 /// This method tests for `self` and `other` values to be equal, and is used
114 #[stable(feature = "rust1", since = "1.0.0")]
115 fn eq(&self, other: &Rhs) -> bool;
117 /// This method tests for `!=`.
120 #[stable(feature = "rust1", since = "1.0.0")]
121 fn ne(&self, other: &Rhs) -> bool { !self.eq(other) }
124 /// Trait for equality comparisons which are [equivalence relations](
125 /// https://en.wikipedia.org/wiki/Equivalence_relation).
127 /// This means, that in addition to `a == b` and `a != b` being strict inverses, the equality must
128 /// be (for all `a`, `b` and `c`):
130 /// - reflexive: `a == a`;
131 /// - symmetric: `a == b` implies `b == a`; and
132 /// - transitive: `a == b` and `b == c` implies `a == c`.
134 /// This property cannot be checked by the compiler, and therefore `Eq` implies
135 /// `PartialEq`, and has no extra methods.
139 /// This trait can be used with `#[derive]`. When `derive`d, because `Eq` has
140 /// no extra methods, it is only informing the compiler that this is an
141 /// equivalence relation rather than a partial equivalence relation. Note that
142 /// the `derive` strategy requires all fields are `Eq`, which isn't
145 /// ## How can I implement `Eq`?
147 /// If you cannot use the `derive` strategy, specify that your type implements
148 /// `Eq`, which has no methods:
151 /// enum BookFormat { Paperback, Hardback, Ebook }
154 /// format: BookFormat,
156 /// impl PartialEq for Book {
157 /// fn eq(&self, other: &Book) -> bool {
158 /// self.isbn == other.isbn
161 /// impl Eq for Book {}
163 #[stable(feature = "rust1", since = "1.0.0")]
164 pub trait Eq: PartialEq<Self> {
165 // FIXME #13101: this method is used solely by #[deriving] to
166 // assert that every component of a type implements #[deriving]
167 // itself, the current deriving infrastructure means doing this
168 // assertion without using a method on this trait is nearly
171 // This should never be implemented by hand.
174 #[stable(feature = "rust1", since = "1.0.0")]
175 fn assert_receiver_is_total_eq(&self) {}
178 // FIXME: this struct is used solely by #[derive] to
179 // assert that every component of a type implements Eq.
181 // This struct should never appear in user code.
183 #[allow(missing_debug_implementations)]
184 #[unstable(feature = "derive_eq",
185 reason = "deriving hack, should not be public",
187 pub struct AssertParamIsEq<T: Eq + ?Sized> { _field: ::marker::PhantomData<T> }
189 /// An `Ordering` is the result of a comparison between two values.
194 /// use std::cmp::Ordering;
196 /// let result = 1.cmp(&2);
197 /// assert_eq!(Ordering::Less, result);
199 /// let result = 1.cmp(&1);
200 /// assert_eq!(Ordering::Equal, result);
202 /// let result = 2.cmp(&1);
203 /// assert_eq!(Ordering::Greater, result);
205 #[derive(Clone, Copy, PartialEq, Debug, Hash)]
206 #[stable(feature = "rust1", since = "1.0.0")]
208 /// An ordering where a compared value is less [than another].
209 #[stable(feature = "rust1", since = "1.0.0")]
211 /// An ordering where a compared value is equal [to another].
212 #[stable(feature = "rust1", since = "1.0.0")]
214 /// An ordering where a compared value is greater [than another].
215 #[stable(feature = "rust1", since = "1.0.0")]
220 /// Reverses the `Ordering`.
222 /// * `Less` becomes `Greater`.
223 /// * `Greater` becomes `Less`.
224 /// * `Equal` becomes `Equal`.
231 /// use std::cmp::Ordering;
233 /// assert_eq!(Ordering::Less.reverse(), Ordering::Greater);
234 /// assert_eq!(Ordering::Equal.reverse(), Ordering::Equal);
235 /// assert_eq!(Ordering::Greater.reverse(), Ordering::Less);
238 /// This method can be used to reverse a comparison:
241 /// let mut data: &mut [_] = &mut [2, 10, 5, 8];
243 /// // sort the array from largest to smallest.
244 /// data.sort_by(|a, b| a.cmp(b).reverse());
246 /// let b: &mut [_] = &mut [10, 8, 5, 2];
247 /// assert!(data == b);
250 #[stable(feature = "rust1", since = "1.0.0")]
251 pub fn reverse(self) -> Ordering {
259 /// Chains two orderings.
261 /// Returns `self` when it's not `Equal`. Otherwise returns `other`.
265 /// use std::cmp::Ordering;
267 /// let result = Ordering::Equal.then(Ordering::Less);
268 /// assert_eq!(result, Ordering::Less);
270 /// let result = Ordering::Less.then(Ordering::Equal);
271 /// assert_eq!(result, Ordering::Less);
273 /// let result = Ordering::Less.then(Ordering::Greater);
274 /// assert_eq!(result, Ordering::Less);
276 /// let result = Ordering::Equal.then(Ordering::Equal);
277 /// assert_eq!(result, Ordering::Equal);
279 /// let x: (i64, i64, i64) = (1, 2, 7);
280 /// let y: (i64, i64, i64) = (1, 5, 3);
281 /// let result = x.0.cmp(&y.0).then(x.1.cmp(&y.1)).then(x.2.cmp(&y.2));
283 /// assert_eq!(result, Ordering::Less);
286 #[stable(feature = "ordering_chaining", since = "1.17.0")]
287 pub fn then(self, other: Ordering) -> Ordering {
294 /// Chains the ordering with the given function.
296 /// Returns `self` when it's not `Equal`. Otherwise calls `f` and returns
302 /// use std::cmp::Ordering;
304 /// let result = Ordering::Equal.then_with(|| Ordering::Less);
305 /// assert_eq!(result, Ordering::Less);
307 /// let result = Ordering::Less.then_with(|| Ordering::Equal);
308 /// assert_eq!(result, Ordering::Less);
310 /// let result = Ordering::Less.then_with(|| Ordering::Greater);
311 /// assert_eq!(result, Ordering::Less);
313 /// let result = Ordering::Equal.then_with(|| Ordering::Equal);
314 /// assert_eq!(result, Ordering::Equal);
316 /// let x: (i64, i64, i64) = (1, 2, 7);
317 /// let y: (i64, i64, i64) = (1, 5, 3);
318 /// let result = x.0.cmp(&y.0).then_with(|| x.1.cmp(&y.1)).then_with(|| x.2.cmp(&y.2));
320 /// assert_eq!(result, Ordering::Less);
323 #[stable(feature = "ordering_chaining", since = "1.17.0")]
324 pub fn then_with<F: FnOnce() -> Ordering>(self, f: F) -> Ordering {
332 /// A helper struct for reverse ordering.
334 /// This struct is a helper to be used with functions like `Vec::sort_by_key` and
335 /// can be used to reverse order a part of a key.
340 /// use std::cmp::Reverse;
342 /// let mut v = vec![1, 2, 3, 4, 5, 6];
343 /// v.sort_by_key(|&num| (num > 3, Reverse(num)));
344 /// assert_eq!(v, vec![3, 2, 1, 6, 5, 4]);
346 #[derive(PartialEq, Eq, Debug)]
347 #[stable(feature = "reverse_cmp_key", since = "1.19.0")]
348 pub struct Reverse<T>(#[stable(feature = "reverse_cmp_key", since = "1.19.0")] pub T);
350 #[stable(feature = "reverse_cmp_key", since = "1.19.0")]
351 impl<T: PartialOrd> PartialOrd for Reverse<T> {
353 fn partial_cmp(&self, other: &Reverse<T>) -> Option<Ordering> {
354 other.0.partial_cmp(&self.0)
358 fn lt(&self, other: &Self) -> bool { other.0 < self.0 }
360 fn le(&self, other: &Self) -> bool { other.0 <= self.0 }
362 fn ge(&self, other: &Self) -> bool { other.0 >= self.0 }
364 fn gt(&self, other: &Self) -> bool { other.0 > self.0 }
367 #[stable(feature = "reverse_cmp_key", since = "1.19.0")]
368 impl<T: Ord> Ord for Reverse<T> {
370 fn cmp(&self, other: &Reverse<T>) -> Ordering {
375 /// Trait for types that form a [total order](https://en.wikipedia.org/wiki/Total_order).
377 /// An order is a total order if it is (for all `a`, `b` and `c`):
379 /// - total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b` is true; and
380 /// - transitive, `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.
384 /// This trait can be used with `#[derive]`. When `derive`d on structs, it will produce a
385 /// lexicographic ordering based on the top-to-bottom declaration order of the struct's members.
386 /// When `derive`d on enums, variants are ordered by their top-to-bottom declaration order.
388 /// ## How can I implement `Ord`?
390 /// `Ord` requires that the type also be `PartialOrd` and `Eq` (which requires `PartialEq`).
392 /// Then you must define an implementation for `cmp()`. You may find it useful to use
393 /// `cmp()` on your type's fields.
395 /// Implementations of `PartialEq`, `PartialOrd`, and `Ord` *must* agree with each other. It's
396 /// easy to accidentally make them disagree by deriving some of the traits and manually
397 /// implementing others.
399 /// Here's an example where you want to sort people by height only, disregarding `id`
403 /// use std::cmp::Ordering;
412 /// impl Ord for Person {
413 /// fn cmp(&self, other: &Person) -> Ordering {
414 /// self.height.cmp(&other.height)
418 /// impl PartialOrd for Person {
419 /// fn partial_cmp(&self, other: &Person) -> Option<Ordering> {
420 /// Some(self.cmp(other))
424 /// impl PartialEq for Person {
425 /// fn eq(&self, other: &Person) -> bool {
426 /// self.height == other.height
430 #[stable(feature = "rust1", since = "1.0.0")]
431 pub trait Ord: Eq + PartialOrd<Self> {
432 /// This method returns an `Ordering` between `self` and `other`.
434 /// By convention, `self.cmp(&other)` returns the ordering matching the expression
435 /// `self <operator> other` if true.
440 /// use std::cmp::Ordering;
442 /// assert_eq!(5.cmp(&10), Ordering::Less);
443 /// assert_eq!(10.cmp(&5), Ordering::Greater);
444 /// assert_eq!(5.cmp(&5), Ordering::Equal);
446 #[stable(feature = "rust1", since = "1.0.0")]
447 fn cmp(&self, other: &Self) -> Ordering;
449 /// Compares and returns the maximum of two values.
451 /// Returns the second argument if the comparison determines them to be equal.
456 /// assert_eq!(2, 1.max(2));
457 /// assert_eq!(2, 2.max(2));
459 #[stable(feature = "ord_max_min", since = "1.22.0")]
460 fn max(self, other: Self) -> Self
462 if other >= self { other } else { self }
465 /// Compares and returns the minimum of two values.
467 /// Returns the first argument if the comparison determines them to be equal.
472 /// assert_eq!(1, 1.min(2));
473 /// assert_eq!(2, 2.min(2));
475 #[stable(feature = "ord_max_min", since = "1.22.0")]
476 fn min(self, other: Self) -> Self
478 if self <= other { self } else { other }
482 #[stable(feature = "rust1", since = "1.0.0")]
483 impl Eq for Ordering {}
485 #[stable(feature = "rust1", since = "1.0.0")]
486 impl Ord for Ordering {
488 fn cmp(&self, other: &Ordering) -> Ordering {
489 (*self as i32).cmp(&(*other as i32))
493 #[stable(feature = "rust1", since = "1.0.0")]
494 impl PartialOrd for Ordering {
496 fn partial_cmp(&self, other: &Ordering) -> Option<Ordering> {
497 (*self as i32).partial_cmp(&(*other as i32))
501 /// Trait for values that can be compared for a sort-order.
503 /// The comparison must satisfy, for all `a`, `b` and `c`:
505 /// - antisymmetry: if `a < b` then `!(a > b)`, as well as `a > b` implying `!(a < b)`; and
506 /// - transitivity: `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.
508 /// Note that these requirements mean that the trait itself must be implemented symmetrically and
509 /// transitively: if `T: PartialOrd<U>` and `U: PartialOrd<V>` then `U: PartialOrd<T>` and `T:
514 /// This trait can be used with `#[derive]`. When `derive`d on structs, it will produce a
515 /// lexicographic ordering based on the top-to-bottom declaration order of the struct's members.
516 /// When `derive`d on enums, variants are ordered by their top-to-bottom declaration order.
518 /// ## How can I implement `PartialOrd`?
520 /// `PartialOrd` only requires implementation of the `partial_cmp` method, with the others
521 /// generated from default implementations.
523 /// However it remains possible to implement the others separately for types which do not have a
524 /// total order. For example, for floating point numbers, `NaN < 0 == false` and `NaN >= 0 ==
525 /// false` (cf. IEEE 754-2008 section 5.11).
527 /// `PartialOrd` requires your type to be `PartialEq`.
529 /// Implementations of `PartialEq`, `PartialOrd`, and `Ord` *must* agree with each other. It's
530 /// easy to accidentally make them disagree by deriving some of the traits and manually
531 /// implementing others.
533 /// If your type is `Ord`, you can implement `partial_cmp()` by using `cmp()`:
536 /// use std::cmp::Ordering;
545 /// impl PartialOrd for Person {
546 /// fn partial_cmp(&self, other: &Person) -> Option<Ordering> {
547 /// Some(self.cmp(other))
551 /// impl Ord for Person {
552 /// fn cmp(&self, other: &Person) -> Ordering {
553 /// self.height.cmp(&other.height)
557 /// impl PartialEq for Person {
558 /// fn eq(&self, other: &Person) -> bool {
559 /// self.height == other.height
564 /// You may also find it useful to use `partial_cmp()` on your type's fields. Here
565 /// is an example of `Person` types who have a floating-point `height` field that
566 /// is the only field to be used for sorting:
569 /// use std::cmp::Ordering;
577 /// impl PartialOrd for Person {
578 /// fn partial_cmp(&self, other: &Person) -> Option<Ordering> {
579 /// self.height.partial_cmp(&other.height)
583 /// impl PartialEq for Person {
584 /// fn eq(&self, other: &Person) -> bool {
585 /// self.height == other.height
596 /// assert_eq!(x < y, true);
597 /// assert_eq!(x.lt(&y), true);
600 #[stable(feature = "rust1", since = "1.0.0")]
601 #[rustc_on_unimplemented = "can't compare `{Self}` with `{Rhs}`"]
602 pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
603 /// This method returns an ordering between `self` and `other` values if one exists.
608 /// use std::cmp::Ordering;
610 /// let result = 1.0.partial_cmp(&2.0);
611 /// assert_eq!(result, Some(Ordering::Less));
613 /// let result = 1.0.partial_cmp(&1.0);
614 /// assert_eq!(result, Some(Ordering::Equal));
616 /// let result = 2.0.partial_cmp(&1.0);
617 /// assert_eq!(result, Some(Ordering::Greater));
620 /// When comparison is impossible:
623 /// let result = std::f64::NAN.partial_cmp(&1.0);
624 /// assert_eq!(result, None);
627 #[stable(feature = "rust1", since = "1.0.0")]
628 fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>;
630 /// This method tests less than (for `self` and `other`) and is used by the `<` operator.
635 /// let result = 1.0 < 2.0;
636 /// assert_eq!(result, true);
638 /// let result = 2.0 < 1.0;
639 /// assert_eq!(result, false);
643 #[stable(feature = "rust1", since = "1.0.0")]
644 fn lt(&self, other: &Rhs) -> bool {
645 match self.partial_cmp(other) {
651 /// This method tests less than or equal to (for `self` and `other`) and is used by the `<=`
657 /// let result = 1.0 <= 2.0;
658 /// assert_eq!(result, true);
660 /// let result = 2.0 <= 2.0;
661 /// assert_eq!(result, true);
665 #[stable(feature = "rust1", since = "1.0.0")]
666 fn le(&self, other: &Rhs) -> bool {
667 match self.partial_cmp(other) {
668 Some(Less) | Some(Equal) => true,
673 /// This method tests greater than (for `self` and `other`) and is used by the `>` operator.
678 /// let result = 1.0 > 2.0;
679 /// assert_eq!(result, false);
681 /// let result = 2.0 > 2.0;
682 /// assert_eq!(result, false);
686 #[stable(feature = "rust1", since = "1.0.0")]
687 fn gt(&self, other: &Rhs) -> bool {
688 match self.partial_cmp(other) {
689 Some(Greater) => true,
694 /// This method tests greater than or equal to (for `self` and `other`) and is used by the `>=`
700 /// let result = 2.0 >= 1.0;
701 /// assert_eq!(result, true);
703 /// let result = 2.0 >= 2.0;
704 /// assert_eq!(result, true);
708 #[stable(feature = "rust1", since = "1.0.0")]
709 fn ge(&self, other: &Rhs) -> bool {
710 match self.partial_cmp(other) {
711 Some(Greater) | Some(Equal) => true,
717 /// Compares and returns the minimum of two values.
719 /// Returns the first argument if the comparison determines them to be equal.
721 /// Internally uses an alias to `Ord::min`.
728 /// assert_eq!(1, cmp::min(1, 2));
729 /// assert_eq!(2, cmp::min(2, 2));
732 #[stable(feature = "rust1", since = "1.0.0")]
733 pub fn min<T: Ord>(v1: T, v2: T) -> T {
737 /// Compares and returns the maximum of two values.
739 /// Returns the second argument if the comparison determines them to be equal.
741 /// Internally uses an alias to `Ord::max`.
748 /// assert_eq!(2, cmp::max(1, 2));
749 /// assert_eq!(2, cmp::max(2, 2));
752 #[stable(feature = "rust1", since = "1.0.0")]
753 pub fn max<T: Ord>(v1: T, v2: T) -> T {
757 // Implementation of PartialEq, Eq, PartialOrd and Ord for primitive types
759 use cmp::Ordering::{self, Less, Greater, Equal};
761 macro_rules! partial_eq_impl {
763 #[stable(feature = "rust1", since = "1.0.0")]
764 impl PartialEq for $t {
766 fn eq(&self, other: &$t) -> bool { (*self) == (*other) }
768 fn ne(&self, other: &$t) -> bool { (*self) != (*other) }
773 #[stable(feature = "rust1", since = "1.0.0")]
774 impl PartialEq for () {
776 fn eq(&self, _other: &()) -> bool { true }
778 fn ne(&self, _other: &()) -> bool { false }
782 bool char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 f32 f64
785 macro_rules! eq_impl {
787 #[stable(feature = "rust1", since = "1.0.0")]
792 eq_impl! { () bool char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
794 macro_rules! partial_ord_impl {
796 #[stable(feature = "rust1", since = "1.0.0")]
797 impl PartialOrd for $t {
799 fn partial_cmp(&self, other: &$t) -> Option<Ordering> {
800 match (self <= other, self >= other) {
801 (false, false) => None,
802 (false, true) => Some(Greater),
803 (true, false) => Some(Less),
804 (true, true) => Some(Equal),
808 fn lt(&self, other: &$t) -> bool { (*self) < (*other) }
810 fn le(&self, other: &$t) -> bool { (*self) <= (*other) }
812 fn ge(&self, other: &$t) -> bool { (*self) >= (*other) }
814 fn gt(&self, other: &$t) -> bool { (*self) > (*other) }
819 #[stable(feature = "rust1", since = "1.0.0")]
820 impl PartialOrd for () {
822 fn partial_cmp(&self, _: &()) -> Option<Ordering> {
827 #[stable(feature = "rust1", since = "1.0.0")]
828 impl PartialOrd for bool {
830 fn partial_cmp(&self, other: &bool) -> Option<Ordering> {
831 (*self as u8).partial_cmp(&(*other as u8))
835 partial_ord_impl! { f32 f64 }
837 macro_rules! ord_impl {
839 #[stable(feature = "rust1", since = "1.0.0")]
840 impl PartialOrd for $t {
842 fn partial_cmp(&self, other: &$t) -> Option<Ordering> {
843 Some(self.cmp(other))
846 fn lt(&self, other: &$t) -> bool { (*self) < (*other) }
848 fn le(&self, other: &$t) -> bool { (*self) <= (*other) }
850 fn ge(&self, other: &$t) -> bool { (*self) >= (*other) }
852 fn gt(&self, other: &$t) -> bool { (*self) > (*other) }
855 #[stable(feature = "rust1", since = "1.0.0")]
858 fn cmp(&self, other: &$t) -> Ordering {
859 if *self == *other { Equal }
860 else if *self < *other { Less }
867 #[stable(feature = "rust1", since = "1.0.0")]
870 fn cmp(&self, _other: &()) -> Ordering { Equal }
873 #[stable(feature = "rust1", since = "1.0.0")]
876 fn cmp(&self, other: &bool) -> Ordering {
877 (*self as u8).cmp(&(*other as u8))
881 ord_impl! { char usize u8 u16 u32 u64 u128 isize i8 i16 i32 i64 i128 }
883 #[unstable(feature = "never_type_impls", issue = "35121")]
884 impl PartialEq for ! {
885 fn eq(&self, _: &!) -> bool {
890 #[unstable(feature = "never_type_impls", issue = "35121")]
893 #[unstable(feature = "never_type_impls", issue = "35121")]
894 impl PartialOrd for ! {
895 fn partial_cmp(&self, _: &!) -> Option<Ordering> {
900 #[unstable(feature = "never_type_impls", issue = "35121")]
902 fn cmp(&self, _: &!) -> Ordering {
909 #[stable(feature = "rust1", since = "1.0.0")]
910 impl<'a, 'b, A: ?Sized, B: ?Sized> PartialEq<&'b B> for &'a A where A: PartialEq<B> {
912 fn eq(&self, other: & &'b B) -> bool { PartialEq::eq(*self, *other) }
914 fn ne(&self, other: & &'b B) -> bool { PartialEq::ne(*self, *other) }
916 #[stable(feature = "rust1", since = "1.0.0")]
917 impl<'a, 'b, A: ?Sized, B: ?Sized> PartialOrd<&'b B> for &'a A where A: PartialOrd<B> {
919 fn partial_cmp(&self, other: &&'b B) -> Option<Ordering> {
920 PartialOrd::partial_cmp(*self, *other)
923 fn lt(&self, other: & &'b B) -> bool { PartialOrd::lt(*self, *other) }
925 fn le(&self, other: & &'b B) -> bool { PartialOrd::le(*self, *other) }
927 fn ge(&self, other: & &'b B) -> bool { PartialOrd::ge(*self, *other) }
929 fn gt(&self, other: & &'b B) -> bool { PartialOrd::gt(*self, *other) }
931 #[stable(feature = "rust1", since = "1.0.0")]
932 impl<'a, A: ?Sized> Ord for &'a A where A: Ord {
934 fn cmp(&self, other: & &'a A) -> Ordering { Ord::cmp(*self, *other) }
936 #[stable(feature = "rust1", since = "1.0.0")]
937 impl<'a, A: ?Sized> Eq for &'a A where A: Eq {}
941 #[stable(feature = "rust1", since = "1.0.0")]
942 impl<'a, 'b, A: ?Sized, B: ?Sized> PartialEq<&'b mut B> for &'a mut A where A: PartialEq<B> {
944 fn eq(&self, other: &&'b mut B) -> bool { PartialEq::eq(*self, *other) }
946 fn ne(&self, other: &&'b mut B) -> bool { PartialEq::ne(*self, *other) }
948 #[stable(feature = "rust1", since = "1.0.0")]
949 impl<'a, 'b, A: ?Sized, B: ?Sized> PartialOrd<&'b mut B> for &'a mut A where A: PartialOrd<B> {
951 fn partial_cmp(&self, other: &&'b mut B) -> Option<Ordering> {
952 PartialOrd::partial_cmp(*self, *other)
955 fn lt(&self, other: &&'b mut B) -> bool { PartialOrd::lt(*self, *other) }
957 fn le(&self, other: &&'b mut B) -> bool { PartialOrd::le(*self, *other) }
959 fn ge(&self, other: &&'b mut B) -> bool { PartialOrd::ge(*self, *other) }
961 fn gt(&self, other: &&'b mut B) -> bool { PartialOrd::gt(*self, *other) }
963 #[stable(feature = "rust1", since = "1.0.0")]
964 impl<'a, A: ?Sized> Ord for &'a mut A where A: Ord {
966 fn cmp(&self, other: &&'a mut A) -> Ordering { Ord::cmp(*self, *other) }
968 #[stable(feature = "rust1", since = "1.0.0")]
969 impl<'a, A: ?Sized> Eq for &'a mut A where A: Eq {}
971 #[stable(feature = "rust1", since = "1.0.0")]
972 impl<'a, 'b, A: ?Sized, B: ?Sized> PartialEq<&'b mut B> for &'a A where A: PartialEq<B> {
974 fn eq(&self, other: &&'b mut B) -> bool { PartialEq::eq(*self, *other) }
976 fn ne(&self, other: &&'b mut B) -> bool { PartialEq::ne(*self, *other) }
979 #[stable(feature = "rust1", since = "1.0.0")]
980 impl<'a, 'b, A: ?Sized, B: ?Sized> PartialEq<&'b B> for &'a mut A where A: PartialEq<B> {
982 fn eq(&self, other: &&'b B) -> bool { PartialEq::eq(*self, *other) }
984 fn ne(&self, other: &&'b B) -> bool { PartialEq::ne(*self, *other) }