From 1c49bf92c844e28c4ae593634f0f0bebce77c341 Mon Sep 17 00:00:00 2001
From: Joshua Coles <josh@coles.to>
Date: Sat, 4 Mar 2023 12:53:12 +0000
Subject: [PATCH] Add N-dimensional position code

---
 src/main.rs       |  2 +
 src/system/mod.rs |  1 +
 src/system/nd.rs  | 99 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 src/system/nd.rs

diff --git a/src/main.rs b/src/main.rs
index 521569f..8b2a1c6 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,5 @@
+#![feature(array_zip)]
+
 use std::path::PathBuf;
 use rand::prelude::*;
 
diff --git a/src/system/mod.rs b/src/system/mod.rs
index 39dacd9..1da8f5f 100644
--- a/src/system/mod.rs
+++ b/src/system/mod.rs
@@ -6,6 +6,7 @@ use serde::{Serialize, Deserialize, Serializer};
 pub mod walker;
 pub mod storage;
 pub mod model;
+pub mod nd;
 
 pub trait GriddedPosition: Add<Output=Self> + Serialize + Clone {
     fn zero() -> Self;
diff --git a/src/system/nd.rs b/src/system/nd.rs
new file mode 100644
index 0000000..a21e223
--- /dev/null
+++ b/src/system/nd.rs
@@ -0,0 +1,99 @@
+use std::ops::Add;
+use rand::Rng;
+use serde::{Serialize, Serializer};
+use serde::ser::SerializeMap;
+use crate::system::GriddedPosition;
+use crate::system::storage::Storage;
+
+pub struct NDVectorStorage<const DIM: usize> {
+    backing: Vec<bool>,
+    grid_size: u32,
+}
+
+impl<const DIM: usize> Storage<NDPosition<DIM>> for NDVectorStorage<DIM> {
+    fn at(&self, position: &NDPosition<DIM>) -> bool {
+        return self.backing[position.linear_index(self.grid_size)];
+    }
+
+    fn deposit(&mut self, position: &NDPosition<DIM>) {
+        self.backing[position.linear_index(self.grid_size)] = true;
+    }
+}
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct NDPosition<const DIM: usize>([i32; DIM]);
+
+impl<const DIM: usize> NDPosition<DIM> {
+    pub fn in_direction(direction: usize, value: i32) -> Self {
+        let mut arr = [0; DIM];
+        arr[direction] = value;
+        NDPosition(arr)
+    }
+}
+
+impl<const DIM: usize> Add for NDPosition<DIM> {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self::Output {
+        Self(self.0.zip(rhs.0).map(|(a, b)| a + b))
+    }
+}
+
+impl<const DIM: usize> Serialize for NDPosition<DIM> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
+        let mut map = serializer.serialize_map(Some(DIM))?;
+        for (i, v) in self.0.iter().enumerate() {
+            map.serialize_entry(&format!("r{}", i), v)?;
+        }
+        map.end()
+    }
+}
+
+impl<const DIM: usize> GriddedPosition for NDPosition<DIM> {
+    fn zero() -> Self {
+        NDPosition([0; DIM])
+    }
+
+    fn spawn<R: Rng>(rng: &mut R, radius: f32) -> Self {
+        let mut a: [f32; DIM] = [0f32; DIM];
+        let mut b: [i32; DIM] = [0i32; DIM];
+
+        for i in 0..DIM {
+            a[i] = rng.gen_range(0f32..1f32);
+        }
+
+        let norm = a.iter().sum::<f32>()
+            .sqrt();
+
+        for i in 0..DIM {
+            a[i] = a[i] / norm;
+            b[i] = a[i] as i32;
+        }
+
+        return Self(b)
+    }
+
+    fn abs(&self) -> f32 {
+        let a: i32 = self.0.iter()
+            .map(|r| r.pow(2))
+            .sum();
+
+        (a as f32).powf(0.5)
+    }
+
+    fn neighbours(&self) -> Vec<Self> {
+        let a = (0..DIM).into_iter();
+
+        return a.flat_map(|direction| [
+            self.clone() + NDPosition::in_direction(direction, 1),
+            self.clone() + NDPosition::in_direction(direction, -1),
+        ]).collect();
+    }
+
+    fn linear_index(&self, grid_size: u32) -> usize {
+        self.0.iter()
+            .enumerate()
+            .map(|(i, v)| (grid_size.pow(i as u32) as usize) * (v + ((grid_size / 2) as i32)) as usize)
+            .sum()
+    }
+}