Introduce `fr`s

2 files changed, 103 insertions, 0 deletions

diff --git a/src/geom/fr.rs b/src/geom/fr.rs
new file mode 100644
index 00000000..974d675e
--- /dev/null
+++ b/src/geom/fr.rs
@@ -0,0 +1,101 @@
+use decorum::N64;
+
+use super::*;
+
+/// A fractional length.
+#[derive(Default, Copy, Clone, PartialEq, PartialOrd, Hash)]
+pub struct Fractional(N64);
+
+impl Fractional {
+    /// Takes up zero space: `0fr`.
+    pub fn zero() -> Self {
+        Self(N64::from(0.0))
+    }
+
+    /// Takes up as much space as all other items with this fractional size: `1fr`.
+    pub fn one() -> Self {
+        Self(N64::from(1.0))
+    }
+
+    /// Create a new fractional value.
+    pub fn new(ratio: f64) -> Self {
+        Self(N64::from(ratio))
+    }
+
+    /// Get the underlying ratio.
+    pub fn get(self) -> f64 {
+        self.0.into()
+    }
+
+    /// Whether the ratio is zero.
+    pub fn is_zero(self) -> bool {
+        self.0 == 0.0
+    }
+}
+
+impl Display for Fractional {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "{}fr", self.get())
+    }
+}
+
+impl Debug for Fractional {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        Display::fmt(self, f)
+    }
+}
+
+impl Neg for Fractional {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self(-self.0)
+    }
+}
+
+impl Add for Fractional {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self(self.0 + other.0)
+    }
+}
+
+sub_impl!(Fractional - Fractional -> Fractional);
+
+impl Mul<f64> for Fractional {
+    type Output = Self;
+
+    fn mul(self, other: f64) -> Self {
+        Self(self.0 * other)
+    }
+}
+
+impl Mul<Fractional> for f64 {
+    type Output = Fractional;
+
+    fn mul(self, other: Fractional) -> Fractional {
+        other * self
+    }
+}
+
+impl Div<f64> for Fractional {
+    type Output = Self;
+
+    fn div(self, other: f64) -> Self {
+        Self(self.0 / other)
+    }
+}
+
+impl Div for Fractional {
+    type Output = f64;
+
+    fn div(self, other: Self) -> f64 {
+        self.get() / other.get()
+    }
+}
+
+assign_impl!(Fractional += Fractional);
+assign_impl!(Fractional -= Fractional);
+assign_impl!(Fractional *= f64);
+assign_impl!(Fractional /= f64);
diff --git a/src/geom/mod.rs b/src/geom/mod.rs
index 0031c6df..ce8a7276 100644
--- a/src/geom/mod.rs
+++ b/src/geom/mod.rs
@@ -5,6 +5,7 @@ mod macros;
 mod align;
 mod angle;
 mod dir;
+mod fr;
 mod gen;
 mod length;
 mod linear;
@@ -18,6 +19,7 @@ mod spec;
 pub use align::*;
 pub use angle::*;
 pub use dir::*;
+pub use fr::*;
 pub use gen::*;
 pub use length::*;
 pub use linear::*;