Add clamp functions #44097

Xaeroxe · 2017-08-26T06:09:34Z

Implementation of clamp feature:

Tracking issue: #44095
RFC: rust-lang/rfcs#1961

rust-highfive · 2017-08-26T06:09:46Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @BurntSushi (or someone else) soon.

If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. Due to the way GitHub handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes.

Please see the contribution instructions for more information.

scottmcm · 2017-08-26T06:45:40Z

src/libstd/f32.rs

+    /// assert!((-3.0f32).clamp(-2.0f32, 1.0f32) == -2.0f32);
+    /// assert!((0.0f32).clamp(-2.0f32, 1.0f32) == 0.0f32);
+    /// assert!((2.0f32).clamp(-2.0f32, 1.0f32) == 1.0f32);
+    /// ```


Perhaps an example of NAN input giving NAN output?

scottmcm · 2017-08-26T06:46:32Z

src/libsyntax/feature_gate.rs

@@ -372,6 +372,9 @@ declare_features! (

    // #[doc(cfg(...))]
    (active, doc_cfg, "1.21.0", Some(43781)),
+
+    // Provide clamp functions
+    (active, clamp, "1.21.0", Some(44095)),


No need for the feature gate in code for lib changes; the attribute is sufficient.

chordowl · 2017-08-26T23:36:02Z

src/libstd/f32.rs

@@ -1080,6 +1080,27 @@ impl f32 {
        0.5 * ((2.0 * self) / (1.0 - self)).ln_1p()
    }

+    /// Returns max if self is greater than max, and min if self is less than min.
+    /// Otherwise this returns self.  Panics if min > max, min equals NaN, or max equals NaN.


Should this be "is NaN" and not "equals NaN"? Nothing is equal (as in ==) to NaN, not even NaN.

chordowl · 2017-08-26T23:36:21Z

src/libstd/f64.rs

@@ -970,6 +970,27 @@ impl f64 {
        0.5 * ((2.0 * self) / (1.0 - self)).ln_1p()
    }

+    /// Returns max if self is greater than max, and min if self is less than min.
+    /// Otherwise this returns self.  Panics if min > max, min equals NaN, or max equals NaN.


Same as above.

carols10cents · 2017-08-28T12:14:19Z

Thanks for the PR! We’ll periodically check in on it to make sure that @BurntSushi or someone else from the team reviews it soon.

BurntSushi · 2017-08-28T12:20:49Z

src/libcore/cmp.rs

@@ -481,6 +481,32 @@ pub trait Ord: Eq + PartialOrd<Self> {
    where Self: Sized {
        if self <= other { self } else { other }
    }
+
+    /// Returns max if self is greater than max, and min if self is less than min.
+    /// Otherwise this will return self.  Panics if min > max.


I think this should follow our doc formatting conventions, no? I think we usually have a panics header for documenting panic'ing conditions.

BurntSushi · 2017-08-28T12:22:09Z

src/libcore/cmp.rs

+        } else {
+            self
+        }
+    }


Could you format this in a way that is consistent with the surrounding code? (Do we do rustmt on this stuff yet?)

BurntSushi · 2017-08-28T12:22:30Z

src/libstd/f32.rs

@@ -1080,6 +1080,29 @@ impl f32 {
        0.5 * ((2.0 * self) / (1.0 - self)).ln_1p()
    }

+    /// Returns max if self is greater than max, and min if self is less than min.
+    /// Otherwise this returns self.  Panics if min > max, min is NaN, or max is NaN.


Needs panic header for here too.

BurntSushi · 2017-08-28T12:22:38Z

src/libstd/f64.rs

@@ -970,6 +970,29 @@ impl f64 {
        0.5 * ((2.0 * self) / (1.0 - self)).ln_1p()
    }

+    /// Returns max if self is greater than max, and min if self is less than min.
+    /// Otherwise this returns self.  Panics if min > max, min is NaN, or max is NaN.


Needs panic header.

BurntSushi

This mostly looks good, but have some nits! I guess this should also technically wait to merge until the RFC has been merged?

Xaeroxe · 2017-09-01T06:09:19Z

r? @BurntSushi

Yeah this will have to wait for the RFC to be merged. I mostly opened this early since the implementation was so straightforward.

BurntSushi

Oh, and could you also add some unit tests for the panic conditions? Thanks!

aturon · 2017-09-06T02:06:25Z

@bors r=burntsushi

bors · 2017-09-06T02:06:26Z

📌 Commit b762283 has been approved by burntsushi

Xaeroxe · 2017-09-06T16:24:48Z

@aturon @BurntSushi That didn't seem to work :/

aturon · 2017-09-06T16:29:39Z

@Xaeroxe it's on the queue, which is pretty backlogged at the moment.

Mark-Simulacrum · 2017-09-06T16:47:29Z

@bors rollup

Add clamp functions Implementation of clamp feature: Tracking issue: rust-lang#44095 RFC: rust-lang/rfcs#1961

StefanoD · 2017-09-06T19:52:09Z

src/libstd/f64.rs

+    /// Panics if min > max, min is NaN, or max is NaN.
+    #[unstable(feature = "clamp", issue = "44095")]
+    #[inline]
+    pub fn clamp(self, min: f64, max: f64) -> f64 {


I'm a Rust beginner, but I think, this should also work. I don't like the mut.

if x < min { min } if x > max { max } else { self }

That was the original implementation. This specific code pattern was chosen because it yields a highly efficient assembly implementation. This was actually the source of quite a bit of conversation before we settled on this.

Oh, interesting and let x?

Yeah, and that.

Holy caroly (this is actually no real word, but it rhymes)!

Add clamp functions Implementation of clamp feature: Tracking issue: rust-lang#44095 RFC: rust-lang/rfcs#1961

Rollup of 23 pull requests - Successful merges: #44097, #44206, #44218, #44276, #44277, #44296, #44303, #44313, #44315, #44317, #44319, #44321, #44325, #44326, #44327, #44328, #44330, #44351, #44353, #44354, #44361, #44362, #44377 - Failed merges:

pcwalton · 2017-09-08T05:55:57Z

This broke Servo and Pathfinder. See servo/app_units#37

rust-highfive assigned BurntSushi Aug 26, 2017

This was referenced Aug 26, 2017

Tracking issue for clamp RFC #44095

Closed

Add clamp RFC rust-lang/rfcs#1961

Merged

Xaeroxe force-pushed the clamp branch from eabd26e to eeb9a28 Compare August 26, 2017 06:29

scottmcm reviewed Aug 26, 2017

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Add clamp functions

c589f86

Xaeroxe force-pushed the clamp branch from eeb9a28 to c589f86 Compare August 26, 2017 16:21

Add NAN examples

f74c5d2

chordowl reviewed Aug 26, 2017

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Xaeroxe added 2 commits August 26, 2017 17:53

Fix f32 examples.

61f20f8

Fix f64 examples

576426a

Xaeroxe changed the title ~~Add clamp functions and feature gate~~ Add clamp functions Aug 27, 2017

carols10cents added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 28, 2017

BurntSushi reviewed Aug 28, 2017

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BurntSushi requested changes Aug 28, 2017

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BurntSushi added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 28, 2017

Fix documentation and formatting.

2e34ff7

BurntSushi requested changes Sep 1, 2017

View reviewed changes

Xaeroxe force-pushed the clamp branch from bd556e7 to c3ff2d4 Compare September 5, 2017 03:10

Add panic unit tests

b762283

Xaeroxe force-pushed the clamp branch from c3ff2d4 to b762283 Compare September 5, 2017 03:39

Mark-Simulacrum added a commit to Mark-Simulacrum/rust that referenced this pull request Sep 6, 2017

Rollup merge of rust-lang#44097 - Xaeroxe:clamp, r=burntsushi

98b1d8c

Add clamp functions Implementation of clamp feature: Tracking issue: rust-lang#44095 RFC: rust-lang/rfcs#1961

Mark-Simulacrum mentioned this pull request Sep 6, 2017

Rollup of 22 pull requests #44369

Closed

StefanoD reviewed Sep 6, 2017

View reviewed changes

Mark-Simulacrum added a commit to Mark-Simulacrum/rust that referenced this pull request Sep 7, 2017

Rollup merge of rust-lang#44097 - Xaeroxe:clamp, r=burntsushi

44351ed

Add clamp functions Implementation of clamp feature: Tracking issue: rust-lang#44095 RFC: rust-lang/rfcs#1961

Mark-Simulacrum mentioned this pull request Sep 7, 2017

Rollup of 23 pull requests #44380

Merged

bors merged commit b762283 into rust-lang:master Sep 7, 2017

Xaeroxe deleted the clamp branch September 7, 2017 21:52

Xaeroxe restored the clamp branch September 8, 2017 21:35

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Add clamp functions #44097

Add clamp functions #44097

Xaeroxe commented Aug 26, 2017

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chordowl Aug 26, 2017 •

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pcwalton commented Sep 8, 2017

Add clamp functions #44097

Add clamp functions #44097

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