Add clamp functions

Author: Xaeroxe

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.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// #![feature(clamp)]
+ ///
+ /// assert!((-3).clamp(-2, 1) == -2);
+ /// assert!(0.clamp(-2, 1) == 0);
+ /// assert!(2.clamp(-2, 1) == 1);
+ /// ```
+ #[unstable(feature = "clamp", issue = "44095")]
+ fn clamp(self, min: Self, max: Self) -> Self
+ where Self: Sized {
+ assert!(min <= max);
+ if self < min {
+ min
+ }
+ else if self > max {
+ max
+ } else {
+ self
+ }
+ }
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]

src/libstd/f32.rs

@@ -1080,6 +1080,26 @@ 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.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// 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);
+ /// ```
+ #[unstable(feature = "clamp", issue = "44095")]
+ #[inline]
+ pub fn clamp(self, min: f32, max: f32) -> f32 {
+ assert!(min <= max);
+ let mut x = self;
+ if x < min { x = min; }
+ if x > max { x = max; }
+ x
+ }
+
  /// Raw transmutation to `u32`.
  ///
  /// Converts the `f32` into its raw memory representation,

src/libstd/f64.rs

@@ -970,6 +970,26 @@ 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.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// assert!((-3.0f64).clamp(-2.0f64, 1.0f64) == -2.0f64);
+ /// assert!((0.0f64).clamp(-2.0f64, 1.0f64) == 0.0f64);
+ /// assert!((2.0f64).clamp(-2.0f64, 1.0f64) == 1.0f64);
+ /// ```
+ #[unstable(feature = "clamp", issue = "44095")]
+ #[inline]
+ pub fn clamp(self, min: f64, max: f64) -> f64 {
+ assert!(min <= max);
+ let mut x = self;
+ if x < min { x = min; }
+ if x > max { x = max; }
+ x
+ }
+
  // Solaris/Illumos requires a wrapper around log, log2, and log10 functions
  // because of their non-standard behavior (e.g. log(-n) returns -Inf instead
  // of expected NaN).