From fa7cc5c241ac644710b2fda7a125b8d8cc62e5ae Mon Sep 17 00:00:00 2001
From: Matej Focko <mfocko@redhat.com>
Date: Thu, 8 Dec 2022 16:02:14 +0100
Subject: [PATCH] vector2d: implement few traits and helpers
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• Derive ordering
• Implement indexing over 2D Vec with a ‹Vector2D›
• Implement boundary checks for ‹Vector2D› indices over 2D Vec
• Implement ‹swap› on ‹Vector2D›
• Implement dot product and scalar product for ‹Vector2D›

Signed-off-by: Matej Focko <mfocko@redhat.com>
---
 src/vector2d.rs | 74 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 72 insertions(+), 2 deletions(-)

diff --git a/src/vector2d.rs b/src/vector2d.rs
index 28b3f16..d89bb15 100644
--- a/src/vector2d.rs
+++ b/src/vector2d.rs
@@ -1,8 +1,9 @@
 use std::cmp::Eq;
+use std::fmt::Debug;
 use std::hash::Hash;
-use std::ops::Add;
+use std::ops::{Add, Mul};
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct Vector2D<T> {
     x: T,
     y: T,
@@ -22,6 +23,53 @@ impl<T> Vector2D<T> {
     }
 }
 
+pub fn index<'a, T, U>(v: &'a [Vec<U>], idx: &Vector2D<T>) -> &'a U
+where
+    usize: TryFrom<T>,
+    <usize as TryFrom<T>>::Error: Debug,
+    T: Copy,
+{
+    let (x, y): (usize, usize) = (idx.y.try_into().unwrap(), idx.x.try_into().unwrap());
+    &v[y][x]
+}
+
+pub fn in_range<T, U>(v: &Vec<Vec<U>>, idx: &Vector2D<T>) -> bool
+where
+    usize: TryInto<T>,
+    <usize as TryInto<T>>::Error: Debug,
+    usize: TryFrom<T>,
+    <usize as TryFrom<T>>::Error: Debug,
+    T: PartialOrd + Copy,
+{
+    idx.y >= 0.try_into().unwrap()
+        && idx.y < v.len().try_into().unwrap()
+        && idx.x >= 0.try_into().unwrap()
+        && idx.x
+            < v[TryInto::<usize>::try_into(idx.y).unwrap()]
+                .len()
+                .try_into()
+                .unwrap()
+}
+
+impl<T: Copy> Vector2D<T> {
+    pub fn swap(&self) -> Self {
+        Self {
+            x: self.y,
+            y: self.x,
+        }
+    }
+}
+
+// See: https://github.com/rust-lang/rust/issues/102731
+// impl<U: From<T>, T> From<Vector2D<T>> for Vector2D<U> {
+//     fn from(value: Vector2D<T>) -> Self {
+//         Self {
+//             x: U::from(value.x),
+//             y: U::from(value.y),
+//         }
+//     }
+// }
+
 impl<T: Add + Add<Output = U>, U> Add for Vector2D<T> {
     type Output = Vector2D<U>;
 
@@ -32,3 +80,25 @@ impl<T: Add + Add<Output = U>, U> Add for Vector2D<T> {
         }
     }
 }
+
+impl<T: Mul + Mul<Output = U>, U> Mul for Vector2D<T> {
+    type Output = Vector2D<U>;
+
+    fn mul(self, rhs: Self) -> Self::Output {
+        Vector2D {
+            x: self.x * rhs.x,
+            y: self.y * rhs.y,
+        }
+    }
+}
+
+impl<T: Mul + Mul<Output = U> + Copy, U> Mul<T> for Vector2D<T> {
+    type Output = Vector2D<U>;
+
+    fn mul(self, rhs: T) -> Self::Output {
+        Vector2D {
+            x: self.x * rhs,
+            y: self.y * rhs,
+        }
+    }
+}