no_std support

Cargo.toml

@@ -8,10 +8,14 @@ repository = "https://github.com/benbaarber/quadtree"
 keywords = ["quadtree", "barnes-hut"]
 
 [features]
+default = ["std"]
+
 serde = ["dep:serde", "glam/serde"]
+std = ["glam/std"]
+libm = ["glam/libm"]
 
 [dependencies]
-glam = "0.30.4"
+glam = { version = "0.30.4", default-features = false, features = ["nostd-libm"] }
 serde = { version = "1.0.219", optional = true, features = ["derive"] }
 
 [dev-dependencies]

src/lib.rs

@@ -1,3 +1,5 @@
+#![no_std]
+
 mod quadtree;
 pub mod shapes;
 mod util;

src/quadtree/barnes_hut.rs

@@ -4,7 +4,10 @@ use crate::{
     util::{Partition, bound_items},
 };
 use glam::Vec2;
-use std::ops::Range;
+
+extern crate alloc;
+use alloc::vec::Vec;
+use core::ops::Range;
 
 /// A point with mass
 #[derive(Debug, Default, Clone, Copy, PartialEq)]

src/quadtree/mod.rs

@@ -1,6 +1,10 @@
 pub mod barnes_hut;
 
 use glam::Vec2;
+
+extern crate alloc;
+use alloc::{boxed::Box, vec, vec::Vec};
+
 #[cfg(feature = "serde")]
 use serde::{Serialize, Serializer, ser::SerializeSeq};
 
@@ -112,6 +116,11 @@ impl<T: Point + Clone> Quadtree<T> {
         results
     }
 
+    /// Shrink to fit inserted items
+    pub fn shrink(&mut self) {
+        self.root = self.root.shrink();
+    }
+
     /// Delete items that are within a specified shape area
     ///
     /// **Returns** the number of items that were deleted
@@ -229,7 +238,7 @@ impl<T: Point + Clone> Node<T> {
                     return true;
                 }
 
-                let mut data = std::mem::take(data);
+                let mut data = core::mem::take(data);
                 data.push(item.clone());
                 let children = self.subdivide();
                 *self = Self::Internal { bound, children };
@@ -487,6 +496,29 @@ impl<T: Point + Clone> Node<T> {
         }
     }
 
+    fn shrink(&mut self) -> Self {
+        let default: Self = Node::Empty {
+            bound: Rect::new(Vec2::default(), Vec2::default()),
+        };
+
+        match self {
+            Self::Empty { .. } => core::mem::replace(self, default),
+            Self::External { .. } => core::mem::replace(self, default),
+            Self::Internal { children, .. } => {
+                let mut nonempty: Vec<&mut Box<Self>> = children
+                    .into_iter()
+                    .filter(|e| !matches!(***e, Node::Empty { .. }))
+                    .collect();
+
+                if nonempty.len() == 1 {
+                    nonempty[0].shrink()
+                } else {
+                    core::mem::replace(self, default)
+                }
+            }
+        }
+    }
+
     fn center(&self) -> Vec2 {
         self.bound().center()
     }

src/util.rs

@@ -1,5 +1,8 @@
 use glam::vec2;
 
+extern crate alloc;
+use alloc::vec::Vec;
+
 use crate::{
     Point,
     shapes::{Rect, Shape},
@@ -56,7 +59,7 @@ impl<T> Partition<T> for [T] {
 }
 
 pub(crate) fn group_by_quadrant<T: Point>(rect: Rect, items: Vec<T>) -> [Vec<T>; 5] {
-    let mut groups: [Vec<T>; 5] = std::array::from_fn(|_| Vec::with_capacity(items.len()));
+    let mut groups: [Vec<T>; 5] = core::array::from_fn(|_| Vec::with_capacity(items.len()));
     for item in items {
         match rect.quadrant(item.point()) {
             Some(q) => groups[q].push(item),
@@ -68,7 +71,7 @@ pub(crate) fn group_by_quadrant<T: Point>(rect: Rect, items: Vec<T>) -> [Vec<T>;
 
 #[allow(unused)]
 pub(crate) fn group_by_quadrant_slice<'a, T: Point>(rect: Rect, items: &'a [T]) -> [Vec<&'a T>; 5] {
-    let mut groups: [Vec<&T>; 5] = std::array::from_fn(|_| Vec::with_capacity(items.len()));
+    let mut groups: [Vec<&T>; 5] = core::array::from_fn(|_| Vec::with_capacity(items.len()));
     for item in items {
         match rect.quadrant(item.point()) {
             Some(q) => groups[q].push(item),