fix: the code in flat_map should now be correct and changed formatting in renderer2d

crates/comet_structs/src/sparse_set.rs

@@ -0,0 +1,91 @@
+use crate::{Component};
+use std::{
+	alloc::{
+		handle_alloc_error,
+		Layout
+	},
+	any::TypeId,
+	collections::{
+		HashMap,
+		HashSet
+	},
+	hash::{
+		DefaultHasher,
+		Hash,
+		Hasher
+	},
+	mem::MaybeUninit,
+	ptr::NonNull
+};
+use std::ptr;
+
+#[derive(Debug, Clone)]
+pub struct SparseSet {
+	sparse: Vec<Option<usize>>,
+	dense: Column,
+	len: usize
+}
+
+impl SparseSet {
+	pub fn new<T: 'static>(capacity: usize) -> Self {
+		Self {
+			sparse: Vec::with_capacity(capacity),
+			dense: Column::new::<T>(capacity),
+			len: 0
+		}
+	}
+
+	pub fn set<T: 'static>(&mut self, index: usize, element: T) {
+		if index >= self.sparse.len() {
+			self.sparse.resize_with(index + 1, || None);
+		}
+
+		if let Some(column_index) = self.sparse[index] {
+			// Explicitly drop the existing component before replacing it
+			unsafe {
+				let existing_ptr = self.dense.data.get_unchecked_mut(column_index) as *mut T;
+				ptr::drop_in_place(existing_ptr);
+				ptr::write(existing_ptr, element);
+			}
+		} else {
+			let column_index = unsafe { self.dense.data.push_uninit() };
+			unsafe {
+				self.dense.data.initialize_unchecked(column_index, &element as *const T as *mut u8);
+			}
+			self.sparse[index] = Some(column_index);
+			self.len += 1;
+		}
+	}
+
+	pub fn remove<T: 'static>(&mut self, index: usize) -> Option<T> {
+		if index >= self.sparse.len() || self.sparse[index] == None {
+			return None;
+		}
+
+		let column_index = self.sparse[index];
+		let element = unsafe {
+			self.dense.data.swap_remove_and_forget_unchecked(column_index.unwrap())
+		};
+
+		self.sparse[index] = None;
+		self.len -= 1;
+
+		Some(unsafe { ptr::read(element as *const T) })
+	}
+
+	pub fn get<T: 'static>(&self, index: usize) -> Option<&T> {
+		if index >= self.sparse.len() || self.sparse[index] == None {
+			return None;
+		}
+
+		self.dense.get::<T>(index)
+	}
+
+	pub fn get_mut<T: 'static>(&mut self, index: usize) -> Option<&mut T> {
+		if index >= self.sparse.len() || self.sparse[index] == None {
+			return None;
+		}
+
+		self.dense.get_mut::<T>(index)
+	}
+}