First pass implementation of Slab collection

source/coral/slab.zig

@@ -0,0 +1,56 @@
+const debug = @import("./debug.zig");
+
+const io = @import("./io.zig");
+
+// TODO: Finish implementing.
+
+pub fn Map(comptime Index: type, comptime Element: type) type {
+	return struct {
+		free_index: Index,
+		entries: []Entry,
+
+		const Entry = union (enum) {
+			free_index: usize,
+			element: Element,
+		};
+
+		const Self = @This();
+
+		pub fn fetch(self: *Self, index: Index) *Element {
+			const entry = &self.entries[index];
+
+			debug.assert(entry.* == .element);
+
+			return &entry.element;
+		}
+
+		pub fn deinit(self: *Self, allocator: io.Allocator) void {
+			io.deallocate(allocator, self.entries);
+		}
+
+		pub fn init(allocator: io.Allocator) io.AllocationError!Self {
+			const entries = try io.allocate_many(Entry, 4, allocator);
+
+			errdefer io.deallocate(allocator, entries);
+
+			return Self{
+				.free_index = 0,
+				.entries = entries,
+			};
+		}
+
+		pub fn insert(self: *Self, allocator: io.Allocator, value: Element) io.AllocationError!Index {
+			_ = self;
+			_ = allocator;
+			_ = value;
+
+			return 0;
+		}
+
+		pub fn remove(self: *Self, index: Index) void {
+			const entry = &self.entries[index];
+
+			debug.assert(entry.* == .element);
+		}
+	};
+}