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+// Copyright 2014 The Servo Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//! A one-dimensional length, tagged with its units.
+
+use crate::approxeq::ApproxEq;
+use crate::num::Zero;
+use crate::scale::Scale;
+use crate::approxord::{max, min};
+
+use crate::num::One;
+use core::cmp::Ordering;
+use core::fmt;
+use core::hash::{Hash, Hasher};
+use core::iter::Sum;
+use core::marker::PhantomData;
+use core::ops::{Add, Div, Mul, Neg, Sub};
+use core::ops::{AddAssign, DivAssign, MulAssign, SubAssign};
+use num_traits::{NumCast, Saturating};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Deserializer, Serialize, Serializer};
+#[cfg(feature = "bytemuck")]
+use bytemuck::{Zeroable, Pod};
+
+/// A one-dimensional distance, with value represented by `T` and unit of measurement `Unit`.
+///
+/// `T` can be any numeric type, for example a primitive type like `u64` or `f32`.
+///
+/// `Unit` is not used in the representation of a `Length` value. It is used only at compile time
+/// to ensure that a `Length` stored with one unit is converted explicitly before being used in an
+/// expression that requires a different unit. It may be a type without values, such as an empty
+/// enum.
+///
+/// You can multiply a `Length` by a `scale::Scale` to convert it from one unit to
+/// another. See the [`Scale`] docs for an example.
+///
+/// [`Scale`]: struct.Scale.html
+#[repr(C)]
+pub struct Length<T, Unit>(pub T, #[doc(hidden)] pub PhantomData<Unit>);
+
+impl<T: Clone, U> Clone for Length<T, U> {
+ fn clone(&self) -> Self {
+ Length(self.0.clone(), PhantomData)
+ }
+}
+
+impl<T: Copy, U> Copy for Length<T, U> {}
+
+#[cfg(feature = "serde")]
+impl<'de, T, U> Deserialize<'de> for Length<T, U>
+where
+ T: Deserialize<'de>,
+{
+ fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+ where
+ D: Deserializer<'de>,
+ {
+ Ok(Length(Deserialize::deserialize(deserializer)?, PhantomData))
+ }
+}
+
+#[cfg(feature = "serde")]
+impl<T, U> Serialize for Length<T, U>
+where
+ T: Serialize,
+{
+ fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+ where
+ S: Serializer,
+ {
+ self.0.serialize(serializer)
+ }
+}
+
+#[cfg(feature = "bytemuck")]
+unsafe impl<T: Zeroable, U> Zeroable for Length<T, U> {}
+
+#[cfg(feature = "bytemuck")]
+unsafe impl<T: Pod, U: 'static> Pod for Length<T, U> {}
+
+impl<T, U> Length<T, U> {
+ /// Associate a value with a unit of measure.
+ #[inline]
+ pub const fn new(x: T) -> Self {
+ Length(x, PhantomData)
+ }
+}
+
+impl<T: Clone, U> Length<T, U> {
+ /// Unpack the underlying value from the wrapper.
+ pub fn get(self) -> T {
+ self.0
+ }
+
+ /// Cast the unit
+ #[inline]
+ pub fn cast_unit<V>(self) -> Length<T, V> {
+ Length::new(self.0)
+ }
+
+ /// Linearly interpolate between this length and another length.
+ ///
+ /// # Example
+ ///
+ /// ```rust
+ /// use euclid::default::Length;
+ ///
+ /// let from = Length::new(0.0);
+ /// let to = Length::new(8.0);
+ ///
+ /// assert_eq!(from.lerp(to, -1.0), Length::new(-8.0));
+ /// assert_eq!(from.lerp(to, 0.0), Length::new( 0.0));
+ /// assert_eq!(from.lerp(to, 0.5), Length::new( 4.0));
+ /// assert_eq!(from.lerp(to, 1.0), Length::new( 8.0));
+ /// assert_eq!(from.lerp(to, 2.0), Length::new(16.0));
+ /// ```
+ #[inline]
+ pub fn lerp(self, other: Self, t: T) -> Self
+ where
+ T: One + Sub<Output = T> + Mul<Output = T> + Add<Output = T>,
+ {
+ let one_t = T::one() - t.clone();
+ Length::new(one_t * self.0.clone() + t * other.0)
+ }
+}
+
+impl<T: PartialOrd, U> Length<T, U> {
+ /// Returns minimum between this length and another length.
+ #[inline]
+ pub fn min(self, other: Self) -> Self {
+ min(self, other)
+ }
+
+ /// Returns maximum between this length and another length.
+ #[inline]
+ pub fn max(self, other: Self) -> Self {
+ max(self, other)
+ }
+}
+
+impl<T: NumCast + Clone, U> Length<T, U> {
+ /// Cast from one numeric representation to another, preserving the units.
+ #[inline]
+ pub fn cast<NewT: NumCast>(self) -> Length<NewT, U> {
+ self.try_cast().unwrap()
+ }
+
+ /// Fallible cast from one numeric representation to another, preserving the units.
+ pub fn try_cast<NewT: NumCast>(self) -> Option<Length<NewT, U>> {
+ NumCast::from(self.0).map(Length::new)
+ }
+}
+
+impl<T: fmt::Debug, U> fmt::Debug for Length<T, U> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ self.0.fmt(f)
+ }
+}
+
+impl<T: Default, U> Default for Length<T, U> {
+ #[inline]
+ fn default() -> Self {
+ Length::new(Default::default())
+ }
+}
+
+impl<T: Hash, U> Hash for Length<T, U> {
+ fn hash<H: Hasher>(&self, h: &mut H) {
+ self.0.hash(h);
+ }
+}
+
+// length + length
+impl<T: Add, U> Add for Length<T, U> {
+ type Output = Length<T::Output, U>;
+
+ fn add(self, other: Self) -> Self::Output {
+ Length::new(self.0 + other.0)
+ }
+}
+
+// length + &length
+impl<T: Add + Copy, U> Add<&Self> for Length<T, U> {
+ type Output = Length<T::Output, U>;
+
+ fn add(self, other: &Self) -> Self::Output {
+ Length::new(self.0 + other.0)
+ }
+}
+
+// length_iter.copied().sum()
+impl<T: Add<Output = T> + Zero, U> Sum for Length<T, U> {
+ fn sum<I: Iterator<Item=Self>>(iter: I) -> Self {
+ iter.fold(Self::zero(), Add::add)
+ }
+}
+
+// length_iter.sum()
+impl<'a, T: 'a + Add<Output = T> + Copy + Zero, U: 'a> Sum<&'a Self> for Length<T, U> {
+ fn sum<I: Iterator<Item=&'a Self>>(iter: I) -> Self {
+ iter.fold(Self::zero(), Add::add)
+ }
+}
+
+// length += length
+impl<T: AddAssign, U> AddAssign for Length<T, U> {
+ fn add_assign(&mut self, other: Self) {
+ self.0 += other.0;
+ }
+}
+
+// length - length
+impl<T: Sub, U> Sub for Length<T, U> {
+ type Output = Length<T::Output, U>;
+
+ fn sub(self, other: Length<T, U>) -> Self::Output {
+ Length::new(self.0 - other.0)
+ }
+}
+
+// length -= length
+impl<T: SubAssign, U> SubAssign for Length<T, U> {
+ fn sub_assign(&mut self, other: Self) {
+ self.0 -= other.0;
+ }
+}
+
+// Saturating length + length and length - length.
+impl<T: Saturating, U> Saturating for Length<T, U> {
+ fn saturating_add(self, other: Self) -> Self {
+ Length::new(self.0.saturating_add(other.0))
+ }
+
+ fn saturating_sub(self, other: Self) -> Self {
+ Length::new(self.0.saturating_sub(other.0))
+ }
+}
+
+// length / length
+impl<Src, Dst, T: Div> Div<Length<T, Src>> for Length<T, Dst> {
+ type Output = Scale<T::Output, Src, Dst>;
+
+ #[inline]
+ fn div(self, other: Length<T, Src>) -> Self::Output {
+ Scale::new(self.0 / other.0)
+ }
+}
+
+// length * scalar
+impl<T: Mul, U> Mul<T> for Length<T, U> {
+ type Output = Length<T::Output, U>;
+
+ #[inline]
+ fn mul(self, scale: T) -> Self::Output {
+ Length::new(self.0 * scale)
+ }
+}
+
+// length *= scalar
+impl<T: Copy + Mul<T, Output = T>, U> MulAssign<T> for Length<T, U> {
+ #[inline]
+ fn mul_assign(&mut self, scale: T) {
+ *self = *self * scale
+ }
+}
+
+// length / scalar
+impl<T: Div, U> Div<T> for Length<T, U> {
+ type Output = Length<T::Output, U>;
+
+ #[inline]
+ fn div(self, scale: T) -> Self::Output {
+ Length::new(self.0 / scale)
+ }
+}
+
+// length /= scalar
+impl<T: Copy + Div<T, Output = T>, U> DivAssign<T> for Length<T, U> {
+ #[inline]
+ fn div_assign(&mut self, scale: T) {
+ *self = *self / scale
+ }
+}
+
+// length * scaleFactor
+impl<Src, Dst, T: Mul> Mul<Scale<T, Src, Dst>> for Length<T, Src> {
+ type Output = Length<T::Output, Dst>;
+
+ #[inline]
+ fn mul(self, scale: Scale<T, Src, Dst>) -> Self::Output {
+ Length::new(self.0 * scale.0)
+ }
+}
+
+// length / scaleFactor
+impl<Src, Dst, T: Div> Div<Scale<T, Src, Dst>> for Length<T, Dst> {
+ type Output = Length<T::Output, Src>;
+
+ #[inline]
+ fn div(self, scale: Scale<T, Src, Dst>) -> Self::Output {
+ Length::new(self.0 / scale.0)
+ }
+}
+
+// -length
+impl<U, T: Neg> Neg for Length<T, U> {
+ type Output = Length<T::Output, U>;
+
+ #[inline]
+ fn neg(self) -> Self::Output {
+ Length::new(-self.0)
+ }
+}
+
+impl<T: PartialEq, U> PartialEq for Length<T, U> {
+ fn eq(&self, other: &Self) -> bool {
+ self.0.eq(&other.0)
+ }
+}
+
+impl<T: PartialOrd, U> PartialOrd for Length<T, U> {
+ fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+ self.0.partial_cmp(&other.0)
+ }
+}
+
+impl<T: Eq, U> Eq for Length<T, U> {}
+
+impl<T: Ord, U> Ord for Length<T, U> {
+ fn cmp(&self, other: &Self) -> Ordering {
+ self.0.cmp(&other.0)
+ }
+}
+
+impl<T: Zero, U> Zero for Length<T, U> {
+ #[inline]
+ fn zero() -> Self {
+ Length::new(Zero::zero())
+ }
+}
+
+impl<U, T: ApproxEq<T>> ApproxEq<T> for Length<T, U> {
+ #[inline]
+ fn approx_epsilon() -> T {
+ T::approx_epsilon()
+ }
+
+ #[inline]
+ fn approx_eq_eps(&self, other: &Length<T, U>, approx_epsilon: &T) -> bool {
+ self.0.approx_eq_eps(&other.0, approx_epsilon)
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use super::Length;
+ use crate::num::Zero;
+
+ use crate::scale::Scale;
+ use core::f32::INFINITY;
+ use num_traits::Saturating;
+
+ enum Inch {}
+ enum Mm {}
+ enum Cm {}
+ enum Second {}
+
+ #[cfg(feature = "serde")]
+ mod serde {
+ use super::*;
+
+ extern crate serde_test;
+ use self::serde_test::assert_tokens;
+ use self::serde_test::Token;
+
+ #[test]
+ fn test_length_serde() {
+ let one_cm: Length<f32, Mm> = Length::new(10.0);
+
+ assert_tokens(&one_cm, &[Token::F32(10.0)]);
+ }
+ }
+
+ #[test]
+ fn test_clone() {
+ // A cloned Length is a separate length with the state matching the
+ // original Length at the point it was cloned.
+ let mut variable_length: Length<f32, Inch> = Length::new(12.0);
+
+ let one_foot = variable_length.clone();
+ variable_length.0 = 24.0;
+
+ assert_eq!(one_foot.get(), 12.0);
+ assert_eq!(variable_length.get(), 24.0);
+ }
+
+ #[test]
+ fn test_add() {
+ let length1: Length<u8, Mm> = Length::new(250);
+ let length2: Length<u8, Mm> = Length::new(5);
+
+ assert_eq!((length1 + length2).get(), 255);
+ assert_eq!((length1 + &length2).get(), 255);
+ }
+
+ #[test]
+ fn test_sum() {
+ type L = Length<f32, Mm>;
+ let lengths = [L::new(1.0), L::new(2.0), L::new(3.0)];
+
+ assert_eq!(lengths.iter().sum::<L>(), L::new(6.0));
+ }
+
+ #[test]
+ fn test_addassign() {
+ let one_cm: Length<f32, Mm> = Length::new(10.0);
+ let mut measurement: Length<f32, Mm> = Length::new(5.0);
+
+ measurement += one_cm;
+
+ assert_eq!(measurement.get(), 15.0);
+ }
+
+ #[test]
+ fn test_sub() {
+ let length1: Length<u8, Mm> = Length::new(250);
+ let length2: Length<u8, Mm> = Length::new(5);
+
+ let result = length1 - length2;
+
+ assert_eq!(result.get(), 245);
+ }
+
+ #[test]
+ fn test_subassign() {
+ let one_cm: Length<f32, Mm> = Length::new(10.0);
+ let mut measurement: Length<f32, Mm> = Length::new(5.0);
+
+ measurement -= one_cm;
+
+ assert_eq!(measurement.get(), -5.0);
+ }
+
+ #[test]
+ fn test_saturating_add() {
+ let length1: Length<u8, Mm> = Length::new(250);
+ let length2: Length<u8, Mm> = Length::new(6);
+
+ let result = length1.saturating_add(length2);
+
+ assert_eq!(result.get(), 255);
+ }
+
+ #[test]
+ fn test_saturating_sub() {
+ let length1: Length<u8, Mm> = Length::new(5);
+ let length2: Length<u8, Mm> = Length::new(10);
+
+ let result = length1.saturating_sub(length2);
+
+ assert_eq!(result.get(), 0);
+ }
+
+ #[test]
+ fn test_division_by_length() {
+ // Division results in a Scale from denominator units
+ // to numerator units.
+ let length: Length<f32, Cm> = Length::new(5.0);
+ let duration: Length<f32, Second> = Length::new(10.0);
+
+ let result = length / duration;
+
+ let expected: Scale<f32, Second, Cm> = Scale::new(0.5);
+ assert_eq!(result, expected);
+ }
+
+ #[test]
+ fn test_multiplication() {
+ let length_mm: Length<f32, Mm> = Length::new(10.0);
+ let cm_per_mm: Scale<f32, Mm, Cm> = Scale::new(0.1);
+
+ let result = length_mm * cm_per_mm;
+
+ let expected: Length<f32, Cm> = Length::new(1.0);
+ assert_eq!(result, expected);
+ }
+
+ #[test]
+ fn test_multiplication_with_scalar() {
+ let length_mm: Length<f32, Mm> = Length::new(10.0);
+
+ let result = length_mm * 2.0;
+
+ let expected: Length<f32, Mm> = Length::new(20.0);
+ assert_eq!(result, expected);
+ }
+
+ #[test]
+ fn test_multiplication_assignment() {
+ let mut length: Length<f32, Mm> = Length::new(10.0);
+
+ length *= 2.0;
+
+ let expected: Length<f32, Mm> = Length::new(20.0);
+ assert_eq!(length, expected);
+ }
+
+ #[test]
+ fn test_division_by_scalefactor() {
+ let length: Length<f32, Cm> = Length::new(5.0);
+ let cm_per_second: Scale<f32, Second, Cm> = Scale::new(10.0);
+
+ let result = length / cm_per_second;
+
+ let expected: Length<f32, Second> = Length::new(0.5);
+ assert_eq!(result, expected);
+ }
+
+ #[test]
+ fn test_division_by_scalar() {
+ let length: Length<f32, Cm> = Length::new(5.0);
+
+ let result = length / 2.0;
+
+ let expected: Length<f32, Cm> = Length::new(2.5);
+ assert_eq!(result, expected);
+ }
+
+ #[test]
+ fn test_division_assignment() {
+ let mut length: Length<f32, Mm> = Length::new(10.0);
+
+ length /= 2.0;
+
+ let expected: Length<f32, Mm> = Length::new(5.0);
+ assert_eq!(length, expected);
+ }
+
+ #[test]
+ fn test_negation() {
+ let length: Length<f32, Cm> = Length::new(5.0);
+
+ let result = -length;
+
+ let expected: Length<f32, Cm> = Length::new(-5.0);
+ assert_eq!(result, expected);
+ }
+
+ #[test]
+ fn test_cast() {
+ let length_as_i32: Length<i32, Cm> = Length::new(5);
+
+ let result: Length<f32, Cm> = length_as_i32.cast();
+
+ let length_as_f32: Length<f32, Cm> = Length::new(5.0);
+ assert_eq!(result, length_as_f32);
+ }
+
+ #[test]
+ fn test_equality() {
+ let length_5_point_0: Length<f32, Cm> = Length::new(5.0);
+ let length_5_point_1: Length<f32, Cm> = Length::new(5.1);
+ let length_0_point_1: Length<f32, Cm> = Length::new(0.1);
+
+ assert!(length_5_point_0 == length_5_point_1 - length_0_point_1);
+ assert!(length_5_point_0 != length_5_point_1);
+ }
+
+ #[test]
+ fn test_order() {
+ let length_5_point_0: Length<f32, Cm> = Length::new(5.0);
+ let length_5_point_1: Length<f32, Cm> = Length::new(5.1);
+ let length_0_point_1: Length<f32, Cm> = Length::new(0.1);
+
+ assert!(length_5_point_0 < length_5_point_1);
+ assert!(length_5_point_0 <= length_5_point_1);
+ assert!(length_5_point_0 <= length_5_point_1 - length_0_point_1);
+ assert!(length_5_point_1 > length_5_point_0);
+ assert!(length_5_point_1 >= length_5_point_0);
+ assert!(length_5_point_0 >= length_5_point_1 - length_0_point_1);
+ }
+
+ #[test]
+ fn test_zero_add() {
+ type LengthCm = Length<f32, Cm>;
+ let length: LengthCm = Length::new(5.0);
+
+ let result = length - LengthCm::zero();
+
+ assert_eq!(result, length);
+ }
+
+ #[test]
+ fn test_zero_division() {
+ type LengthCm = Length<f32, Cm>;
+ let length: LengthCm = Length::new(5.0);
+ let length_zero: LengthCm = Length::zero();
+
+ let result = length / length_zero;
+
+ let expected: Scale<f32, Cm, Cm> = Scale::new(INFINITY);
+ assert_eq!(result, expected);
+ }
+}