From d7d4e670ed53883672d8c4458226d91dcc731569 Mon Sep 17 00:00:00 2001 From: Armin Ronacher Date: Wed, 22 Mar 2017 00:01:37 +0100 Subject: [PATCH 1/5] Added core::cmp::Reverse for sort_by_key reverse sorting --- src/libcore/cmp.rs | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs index cb39796eecd7d..d87615ad9a2c2 100644 --- a/src/libcore/cmp.rs +++ b/src/libcore/cmp.rs @@ -322,6 +322,40 @@ impl Ordering { } } +/// 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. +/// +/// Example usage: +/// +/// ``` +/// 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]); +/// ``` +#[derive(PartialEq, Eq, Debug)] +#[stable(feature = "rust1", since = "1.8.0")] +pub struct Reverse(pub T); + +#[stable(feature = "rust1", since = "1.8.0")] +impl PartialOrd for Reverse { + #[inline] + fn partial_cmp(&self, other: &Reverse) -> Option { + other.0.partial_cmp(&self.0) + } +} + +#[stable(feature = "rust1", since = "1.8.0")] +impl Ord for Reverse { + #[inline] + fn cmp(&self, other: &Reverse) -> Ordering { + other.0.cmp(&self.0) + } +} + /// Trait for types that form a [total order](https://en.wikipedia.org/wiki/Total_order). /// /// An order is a total order if it is (for all `a`, `b` and `c`): From dabff151426d0cf6f8a779c15be459f7bd457a4c Mon Sep 17 00:00:00 2001 From: Armin Ronacher Date: Wed, 22 Mar 2017 09:04:42 +0100 Subject: [PATCH 2/5] Fix the test for cmp::Reverse --- src/libcore/cmp.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs index d87615ad9a2c2..d787a0833c7ab 100644 --- a/src/libcore/cmp.rs +++ b/src/libcore/cmp.rs @@ -333,7 +333,7 @@ impl Ordering { /// use std::cmp::Reverse; /// /// let mut v = vec![1, 2, 3, 4, 5, 6]; -/// v.sort_by_key(|&num| (num >= 3, Reverse(num))); +/// v.sort_by_key(|&num| (num > 3, Reverse(num))); /// assert_eq!(v, vec![3, 2, 1, 6, 5, 4]); /// ``` #[derive(PartialEq, Eq, Debug)] From d005d917783b8f753b4ee2f79f03e2212e519d01 Mon Sep 17 00:00:00 2001 From: Armin Ronacher Date: Wed, 22 Mar 2017 14:16:41 +0100 Subject: [PATCH 3/5] Improved bounds for cmp::Reverse --- src/libcore/cmp.rs | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs index d787a0833c7ab..751932a6105ae 100644 --- a/src/libcore/cmp.rs +++ b/src/libcore/cmp.rs @@ -337,19 +337,19 @@ impl Ordering { /// assert_eq!(v, vec![3, 2, 1, 6, 5, 4]); /// ``` #[derive(PartialEq, Eq, Debug)] -#[stable(feature = "rust1", since = "1.8.0")] -pub struct Reverse(pub T); +#[stable(feature = "rust1", since = "1.18.0")] +pub struct Reverse(pub T); -#[stable(feature = "rust1", since = "1.8.0")] -impl PartialOrd for Reverse { +#[stable(feature = "rust1", since = "1.18.0")] +impl PartialOrd for Reverse { #[inline] fn partial_cmp(&self, other: &Reverse) -> Option { other.0.partial_cmp(&self.0) } } -#[stable(feature = "rust1", since = "1.8.0")] -impl Ord for Reverse { +#[stable(feature = "rust1", since = "1.18.0")] +impl Ord for Reverse { #[inline] fn cmp(&self, other: &Reverse) -> Ordering { other.0.cmp(&self.0) From 7efbb69b99cf6b88027b3ec0a3d12771703831e7 Mon Sep 17 00:00:00 2001 From: Armin Ronacher Date: Wed, 29 Mar 2017 01:18:39 +0200 Subject: [PATCH 4/5] Changed cmp::Reverse to unstable --- src/libcore/cmp.rs | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs index 751932a6105ae..a43c85328731f 100644 --- a/src/libcore/cmp.rs +++ b/src/libcore/cmp.rs @@ -330,6 +330,7 @@ impl Ordering { /// Example usage: /// /// ``` +/// #![feature(reverse_cmp_key)] /// use std::cmp::Reverse; /// /// let mut v = vec![1, 2, 3, 4, 5, 6]; @@ -337,10 +338,10 @@ impl Ordering { /// assert_eq!(v, vec![3, 2, 1, 6, 5, 4]); /// ``` #[derive(PartialEq, Eq, Debug)] -#[stable(feature = "rust1", since = "1.18.0")] +#[unstable(feature = "reverse_cmp_key", issue = "40720")] pub struct Reverse(pub T); -#[stable(feature = "rust1", since = "1.18.0")] +#[unstable(feature = "reverse_cmp_key", issue = "40720")] impl PartialOrd for Reverse { #[inline] fn partial_cmp(&self, other: &Reverse) -> Option { @@ -348,7 +349,7 @@ impl PartialOrd for Reverse { } } -#[stable(feature = "rust1", since = "1.18.0")] +#[unstable(feature = "reverse_cmp_key", issue = "40720")] impl Ord for Reverse { #[inline] fn cmp(&self, other: &Reverse) -> Ordering { From 5d3695362f795a45947e92c77f910dcacba575ea Mon Sep 17 00:00:00 2001 From: Armin Ronacher Date: Wed, 29 Mar 2017 09:06:52 +0200 Subject: [PATCH 5/5] Updated tracking issue for cmp::Reverse --- src/libcore/cmp.rs | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs index a43c85328731f..bdfd55b100289 100644 --- a/src/libcore/cmp.rs +++ b/src/libcore/cmp.rs @@ -338,10 +338,10 @@ impl Ordering { /// assert_eq!(v, vec![3, 2, 1, 6, 5, 4]); /// ``` #[derive(PartialEq, Eq, Debug)] -#[unstable(feature = "reverse_cmp_key", issue = "40720")] +#[unstable(feature = "reverse_cmp_key", issue = "40893")] pub struct Reverse(pub T); -#[unstable(feature = "reverse_cmp_key", issue = "40720")] +#[unstable(feature = "reverse_cmp_key", issue = "40893")] impl PartialOrd for Reverse { #[inline] fn partial_cmp(&self, other: &Reverse) -> Option { @@ -349,7 +349,7 @@ impl PartialOrd for Reverse { } } -#[unstable(feature = "reverse_cmp_key", issue = "40720")] +#[unstable(feature = "reverse_cmp_key", issue = "40893")] impl Ord for Reverse { #[inline] fn cmp(&self, other: &Reverse) -> Ordering {