diff --git a/src/libcore/cmp.rs b/src/libcore/cmp.rs index 81fcdeee12d29..259135b9ca0ab 100644 --- a/src/libcore/cmp.rs +++ b/src/libcore/cmp.rs @@ -567,6 +567,32 @@ pub trait Ord: Eq + PartialOrd { 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")] diff --git a/src/libstd/f32.rs b/src/libstd/f32.rs index f6cd9e82abd40..a2b12d00a78c2 100644 --- a/src/libstd/f32.rs +++ b/src/libstd/f32.rs @@ -956,6 +956,27 @@ impl f32 { pub fn atanh(self) -> 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 + /// + /// ``` + /// #![feature(clamp)] + /// 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 + } + } #[cfg(test)] diff --git a/src/libstd/f64.rs b/src/libstd/f64.rs index 8ff97ab828a73..be5cd92d4167b 100644 --- a/src/libstd/f64.rs +++ b/src/libstd/f64.rs @@ -878,6 +878,27 @@ 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. + /// + /// # Examples + /// + /// ``` + /// #![feature(clamp)] + /// 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). diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs index e31680f23f1da..b830c90cc434b 100644 --- a/src/libstd/lib.rs +++ b/src/libstd/lib.rs @@ -245,6 +245,7 @@ #![feature(cfg_target_thread_local)] #![feature(char_error_internals)] #![feature(checked_duration_since)] +#![feature(clamp)] #![feature(compiler_builtins_lib)] #![feature(concat_idents)] #![feature(const_cstr_unchecked)]