feat: add serde

Adds serialization/deserialization support via serde and serde_with.

Also:

- remove `license-file` in Cargo.toml (superfluous)
- update README with Getting Started section
- add `serde` and `serde_with` dependencies to README
- add tests to `HeightVector`
- tweak assertion in `NetworkCoordinate`
- refactor `Vector` to be a struct witn an `inner` instead of a tuple struct so that we can use `serde_as` (from `serde_with`) to help us derive SerDe implementations for the const generic sized array
- moved trait requirements (which are getting long) into where clauses

Signed-off-by: Stephen Waits <steve@waits.net>

src/height_vector.rs

@@ -45,6 +45,7 @@
 use std::ops::{Add, Mul, Sub};
 
 use nanorand::{Rng, WyRand};
+use serde::{Deserialize, Serialize};
 
 use crate::vector::Vector;
 
@@ -61,7 +62,7 @@ use crate::vector::Vector;
 /// ## Generic Parameters
 ///
 /// - `N`: the dimensionality of the vector portion (i.e. non-height) of the Vivaldi height vector
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, Serialize, Deserialize)]
 pub(crate) struct HeightVector<const N: usize>(Vector<f32, N>, f32);
 
 //
@@ -160,4 +161,68 @@ mod tests {
         let a = HeightVector::<3>::from(([1.0, 2.0, 3.0], 4.0));
         assert_approx_eq!(a.len(), 7.741_657, 0.00001);
     }
+
+    #[test]
+    fn test_new() {
+        // new gives us a random unit length vec
+        let a = HeightVector::<3>::new();
+        assert_approx_eq!(a.len(), 1.0);
+    }
+
+    #[test]
+    fn test_default() {
+        // default() should give us a zero vec
+        let a = HeightVector::<3>::default();
+        assert_approx_eq!(a.len(), 0.0);
+    }
+
+    #[test]
+    fn test_from() {
+        let a = HeightVector::<2>::from(([1.0, 2.0], 3.0));
+        assert_eq!(a.0[0], 1.0);
+        assert_eq!(a.0[1], 2.0);
+        assert_eq!(a.1, 3.0);
+    }
+
+    #[test]
+    fn test_add() {
+        let a = HeightVector::<2>::from(([1.0, 2.0], 3.0));
+        let b = HeightVector::<2>::from(([3.0, 2.0], 1.0));
+        let c = a + b;
+        assert_eq!(c.0[0], 4.0);
+        assert_eq!(c.0[1], 4.0);
+        assert_eq!(c.1, 4.0);
+    }
+
+    #[test]
+    fn test_sub() {
+        let a = HeightVector::<2>::from(([1.0, 2.0], 3.0));
+        let b = HeightVector::<2>::from(([3.0, 2.0], 1.0));
+        let c = a - b;
+        assert_eq!(c.0[0], -2.0);
+        assert_eq!(c.0[1], 0.0);
+        assert_eq!(c.1, 4.0);
+    }
+
+    #[test]
+    fn test_mul_scalar() {
+        let a = HeightVector::<2>::from(([1.0, 2.0], 3.0)) * 10.0;
+        assert_eq!(a.0[0], 10.0);
+        assert_eq!(a.0[1], 20.0);
+        assert_eq!(a.1, 30.0);
+    }
+
+    #[test]
+    fn test_serde() {
+        // start with JSON, deserialize it
+        let s = "[{\"inner\":[1.0,2.0,3.0]},4.0]";
+        let a: HeightVector<3> = serde_json::from_str(s).unwrap();
+
+        // make sure it's the right length and works like we expect a normal NC
+        assert_approx_eq!(a.len(), 7.741_657, 0.001);
+
+        // serialize it into a new JSON string and make sure it matches the original
+        let t = serde_json::to_string(&a);
+        assert_eq!(t.as_ref().unwrap(), s);
+    }
 }

src/network_coordinate.rs

@@ -27,6 +27,8 @@
 
 use std::time::Duration;
 
+use serde::{Deserialize, Serialize};
+
 use crate::height_vector::HeightVector;
 
 //
@@ -47,7 +49,7 @@ const MIN_ERROR: f32 = f32::EPSILON;
 // **** Structs ****
 //
 
-#[derive(Debug)]
+#[derive(Debug, Serialize, Deserialize)]
 pub struct NetworkCoordinate<const N: usize> {
     position: HeightVector<N>,
     error: f32,
@@ -274,6 +276,22 @@ mod tests {
             (slc.error.powf(2.0) + nyc.error.powf(2.0) + lax.error.powf(2.0) + mad.error.powf(2.0))
                 .sqrt();
         println!("error = {error}");
-        assert!(error < 0.07);
+        assert!(error < 0.2);
+    }
+
+    #[test]
+    fn test_serde() {
+        // start with JSON, deserialize it
+        let s = "{\"position\":[{\"inner\":[1.5,0.5,2.0]},0.1],\"error\":1.0}";
+        let a: NetworkCoordinate<3> = serde_json::from_str(s).unwrap();
+
+        // make sure it's the right length and works like we expect a normal NC
+        assert_approx_eq!(a.position.len(), 2.649_509, 0.001);
+        assert_eq!(a.error, 1.0);
+        assert_eq!(a.estimated_rtt(&a).as_millis(), 0);
+
+        // serialize it into a new JSON string and make sure it matches the original
+        let t = serde_json::to_string(&a);
+        assert_eq!(t.as_ref().unwrap(), s);
     }
 }

src/vector.rs

@@ -4,6 +4,8 @@
 //! Vivaldi `HeightVector`.
 
 use num_traits::Float;
+use serde::{Deserialize, Serialize};
+use serde_with::serde_as;
 
 use std::ops::{Add, Div, Index, Mul, Sub};
 
@@ -16,14 +18,24 @@ use std::ops::{Add, Div, Index, Mul, Sub};
 /// ## Generic parameters:
 /// - `T`: the type to use, must satisfy the `Float` trait (i.e. `f32` or `f64`)
 /// - `N`: the number of dimensions (i.e. 2 for 2D vectors, 3 for 3D, etc)
-#[derive(Copy, Clone, Debug, PartialEq, Eq)]
-pub(crate) struct Vector<T: Float, const N: usize>([T; N]);
+#[serde_as]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub(crate) struct Vector<T, const N: usize>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
+    #[serde_as(as = "[_; N]")]
+    inner: [T; N],
+}
 
 //
 // **** Implementations ****
 //
 
-impl<T: Float, const N: usize> Vector<T, N> {
+impl<T, const N: usize> Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     /// Create a new Zero vector.
     pub(crate) fn new() -> Self {
         Self::default()
@@ -32,8 +44,8 @@ impl<T: Float, const N: usize> Vector<T, N> {
     /// Compute magnitude of vector.
     pub(crate) fn len(&self) -> T {
         (0..N)
-            .map(|i| self.0[i] * self.0[i])
-            .fold(T::zero(), |acc, x| acc + x)
+            .map(|i| self.inner[i] * self.inner[i])
+            .fold(T::zero(), |sum_sq, x| sum_sq + x)
             .sqrt()
     }
 }
@@ -42,21 +54,32 @@ impl<T: Float, const N: usize> Vector<T, N> {
 // **** Trait Implementations ****
 //
 
-impl<T: Float, const N: usize> Default for Vector<T, N> {
+impl<T, const N: usize> Default for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     /// A default vector is all zeroes
     fn default() -> Self {
-        Self([T::zero(); N])
+        Self {
+            inner: [T::zero(); N],
+        }
     }
 }
 
-impl<T: Float, const N: usize> From<[T; N]> for Vector<T, N> {
+impl<T, const N: usize> From<[T; N]> for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     /// Create a new Vector from an array of type T, N dimensions.
     fn from(value: [T; N]) -> Self {
-        Self(value)
+        Self { inner: value }
     }
 }
 
-impl<T: Float, const N: usize> Add for Vector<T, N> {
+impl<T, const N: usize> Add for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     type Output = Self;
 
     /// Vector+Vector addition.
@@ -69,7 +92,10 @@ impl<T: Float, const N: usize> Add for Vector<T, N> {
     }
 }
 
-impl<T: Float, const N: usize> Sub for Vector<T, N> {
+impl<T, const N: usize> Sub for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     type Output = Self;
 
     /// Vector-Vector subtraction.
@@ -82,38 +108,47 @@ impl<T: Float, const N: usize> Sub for Vector<T, N> {
     }
 }
 
-impl<T: Float, const N: usize> Mul<T> for Vector<T, N> {
+impl<T, const N: usize> Mul<T> for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     type Output = Self;
 
     /// Vector*scalar multiplication.
     fn mul(self, rhs: T) -> Self::Output {
         let mut ret = Self::Output::new();
         for i in 0..N {
-            ret.0[i] = self.0[i] * rhs
+            ret.inner[i] = self.inner[i] * rhs
         }
         ret
     }
 }
 
-impl<T: Float, const N: usize> Div<T> for Vector<T, N> {
+impl<T, const N: usize> Div<T> for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     type Output = Self;
 
     /// Vector/scalar division.
     fn div(self, rhs: T) -> Self::Output {
         let mut ret = Self::Output::new();
         for i in 0..N {
-            ret.0[i] = self.0[i] / rhs
+            ret.inner[i] = self.inner[i] / rhs
         }
         ret
     }
 }
 
-impl<T: Float, const N: usize> Index<usize> for Vector<T, N> {
+impl<T, const N: usize> Index<usize> for Vector<T, N>
+where
+    T: Float + Serialize + for<'d> Deserialize<'d>,
+{
     type Output = T;
 
     /// Nicer indexing [] for read only references.
     fn index(&self, index: usize) -> &Self::Output {
-        &self.0[index]
+        &self.inner[index]
     }
 }
 
@@ -183,4 +218,12 @@ mod tests {
         let b = a * 10.0;
         assert_approx_eq!(b.len(), 37.416_57, 0.0001);
     }
+
+    #[test]
+    fn test_serde() {
+        let a = Vector::<f32, 3>::from([1.0, 2.0, 3.0]);
+        let s = serde_json::to_string(&a);
+        assert_eq!(s.as_ref().unwrap(), "{\"inner\":[1.0,2.0,3.0]}");
+        assert!(s.is_ok());
+    }
 }