Add way to remove elements from dense slot maps

source/coral/slots.zig

@@ -97,8 +97,33 @@ pub fn Dense(comptime key: Key, comptime Element: type) type {
 			};
 		}
 
-		pub fn remove(_: *Self, _: u128) bool {
-			// TODO: Implement.
+		pub fn remove(self: *Self, slot: KeySlot) bool {
+			const redirect = &self.slots[slot.index];
+
+			if (slot.salt != redirect.salt) {
+				return false;
+			}
+
+			const free_index = redirect.index;
+
+			self.values = self.values[0 .. (self.values.len - 1)];
+
+			if (self.values.len > 0) {
+				const free_data = &self.data[free_index];
+				const free_erase = &self.erase[free_index];
+				const last_data = &self.data[self.values.len];
+				const last_erase = &self.erase[self.values.len];
+
+				free_data.* = last_data.*;
+				free_erase.* = last_erase.*;
+				self.slots[free_erase.*].index = free_index;
+			}
+
+			redirect.salt = math.max(redirect.salt +% 1, 1);
+			redirect.index = self.next_free;
+			self.next_free = slot.index;
+
+			return true;
 		}
 	};
 }