ecs: pass an all_components parameter to everything

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

ecs/src/entities.zig

@@ -340,7 +340,9 @@ pub const void_archetype_hash = std.math.maxInt(u64);
 ///   row index, enabling entities to "move" from one archetype table to another seamlessly and
 ///   making lookup by entity ID a few cheap array indexing operations.
 /// * ComponentStorage(T) is a column of data within a table for a single type of component `T`.
-pub const Entities = struct {
+pub fn Entities(all_components: anytype) type {
+    _ = all_components;
+    return struct {
         allocator: Allocator,
 
         /// TODO!
@@ -355,6 +357,8 @@ pub const Entities = struct {
         /// Database equivalent: table name -> tables representing entities.
         archetypes: std.AutoArrayHashMapUnmanaged(u64, ArchetypeStorage) = .{},
 
+        const Self = @This();
+
         /// Points to where an entity is stored, specifically in which archetype table and in which row
         /// of that table. That is, the entity's component values are stored at:
         ///
@@ -368,7 +372,7 @@ pub const Entities = struct {
         };
 
         pub const Iterator = struct {
-        entities: *Entities,
+            entities: *Self,
             components: []const []const u8,
             archetype_index: usize = 0,
             row_index: u32 = 0,
@@ -402,15 +406,15 @@ pub const Entities = struct {
             }
         };
 
-    pub fn query(entities: *Entities, components: []const []const u8) Iterator {
+        pub fn query(entities: *Self, components: []const []const u8) Iterator {
             return Iterator{
                 .entities = entities,
                 .components = components,
             };
         }
 
-    pub fn init(allocator: Allocator) !Entities {
-        var entities = Entities{ .allocator = allocator };
+        pub fn init(allocator: Allocator) !Self {
+            var entities = Self{ .allocator = allocator };
 
             const columns = try allocator.alloc(Column, 1);
             columns[0] = .{
@@ -433,7 +437,7 @@ pub const Entities = struct {
             return entities;
         }
 
-    pub fn deinit(entities: *Entities) void {
+        pub fn deinit(entities: *Self) void {
             entities.entities.deinit(entities.allocator);
 
             var iter = entities.archetypes.iterator();
@@ -445,7 +449,7 @@ pub const Entities = struct {
         }
 
         /// Returns a new entity.
-    pub fn new(entities: *Entities) !EntityID {
+        pub fn new(entities: *Self) !EntityID {
             const new_id = entities.counter;
             entities.counter += 1;
 
@@ -464,7 +468,7 @@ pub const Entities = struct {
         }
 
         /// Removes an entity.
-    pub fn remove(entities: *Entities, entity: EntityID) !void {
+        pub fn remove(entities: *Self, entity: EntityID) !void {
             var archetype = entities.archetypeByID(entity);
             const ptr = entities.entities.get(entity).?;
 
@@ -485,7 +489,7 @@ pub const Entities = struct {
         }
 
         /// Returns the archetype storage for the given entity.
-    pub inline fn archetypeByID(entities: *Entities, entity: EntityID) *ArchetypeStorage {
+        pub inline fn archetypeByID(entities: *Self, entity: EntityID) *ArchetypeStorage {
             const ptr = entities.entities.get(entity).?;
             return &entities.archetypes.values()[ptr.archetype_index];
         }
@@ -493,7 +497,7 @@ pub const Entities = struct {
         /// Sets the named component to the specified value for the given entity,
         /// moving the entity from it's current archetype table to the new archetype
         /// table if required.
-    pub fn setComponent(entities: *Entities, entity: EntityID, comptime name: []const u8, component: anytype) !void {
+        pub fn setComponent(entities: *Self, entity: EntityID, comptime name: []const u8, component: anytype) !void {
             var archetype = entities.archetypeByID(entity);
 
             // Determine the old hash for the archetype.
@@ -591,7 +595,7 @@ pub const Entities = struct {
 
         /// gets the named component of the given type (which must be correct, otherwise undefined
         /// behavior will occur). Returns null if the component does not exist on the entity.
-    pub fn getComponent(entities: *Entities, entity: EntityID, name: []const u8, comptime Component: type) ?Component {
+        pub fn getComponent(entities: *Self, entity: EntityID, name: []const u8, comptime Component: type) ?Component {
             var archetype = entities.archetypeByID(entity);
 
             const ptr = entities.entities.get(entity).?;
@@ -599,7 +603,7 @@ pub const Entities = struct {
         }
 
         /// Removes the named component from the entity, or noop if it doesn't have such a component.
-    pub fn removeComponent(entities: *Entities, entity: EntityID, name: []const u8) !void {
+        pub fn removeComponent(entities: *Self, entity: EntityID, name: []const u8) !void {
             var archetype = entities.archetypeByID(entity);
             if (!archetype.hasComponent(name)) return;
 
@@ -698,7 +702,8 @@ pub const Entities = struct {
 
         // TODO: ability to remove archetype entirely, deleting all entities in it
         // TODO: ability to remove archetypes with no entities (garbage collection)
-};
+    };
+}
 
 test "entity ID size" {
     try testing.expectEqual(8, @sizeOf(EntityID));
@@ -707,9 +712,11 @@ test "entity ID size" {
 test "example" {
     const allocator = testing.allocator;
 
+    const all_components = .{};
+
     //-------------------------------------------------------------------------
     // Create a world.
-    var world = try Entities.init(allocator);
+    var world = try Entities(all_components).init(allocator);
     defer world.deinit();
 
     //-------------------------------------------------------------------------

ecs/src/main.zig

@@ -46,9 +46,11 @@ test "inclusion" {
 test "example" {
     const allocator = testing.allocator;
 
+    const all_components = .{};
+
     //-------------------------------------------------------------------------
     // Create a world.
-    var world = try World.init(allocator);
+    var world = try World(all_components).init(allocator);
     defer world.deinit();
 
     const player1 = try world.entities.new();
@@ -61,7 +63,7 @@ test "example" {
     try world.entities.setComponent(player3, "physics", @as(u16, 1234));
 
     const physics = (struct {
-        pub fn physics(adapter: *Adapter) void {
+        pub fn physics(adapter: *Adapter(all_components)) void {
             var iter = adapter.query(&.{"physics"});
             std.debug.print("\nphysics ran\n", .{});
             while (iter.next()) |row| {
@@ -73,7 +75,7 @@ test "example" {
     try world.register("physics", physics);
 
     const rendering = (struct {
-        pub fn rendering(adapter: *Adapter) void {
+        pub fn rendering(adapter: *Adapter(all_components)) void {
             var iter = adapter.query(&.{"geometry"});
             std.debug.print("\nrendering ran\n", .{});
             while (iter.next()) |row| {

ecs/src/systems.zig

@@ -4,52 +4,59 @@ const Allocator = mem.Allocator;
 const testing = std.testing;
 
 const Entities = @import("entities.zig").Entities;
-const Iterator = Entities.Iterator;
 
-pub const Adapter = struct {
-    world: *World,
+pub fn Adapter(all_components: anytype) type {
+    return struct {
+        world: *World(all_components),
 
-    pub fn query(adapter: *Adapter, components: []const []const u8) Iterator {
+        const Self = @This();
+        pub const Iterator = Entities(all_components).Iterator;
+
+        pub fn query(adapter: *Self, components: []const []const u8) Iterator {
             return adapter.world.entities.query(components);
         }
-};
+    };
+}
 
-pub const System = fn (adapter: *Adapter) void;
-
-pub const World = struct {
+pub fn World(all_components: anytype) type {
+    return struct {
         allocator: Allocator,
         systems: std.StringArrayHashMapUnmanaged(System) = .{},
-    entities: Entities,
+        entities: Entities(all_components),
 
-    pub fn init(allocator: Allocator) !World {
-        return World{
+        const Self = @This();
+        pub const System = fn (adapter: *Adapter(all_components)) void;
+
+        pub fn init(allocator: Allocator) !Self {
+            return Self{
                 .allocator = allocator,
-            .entities = try Entities.init(allocator),
+                .entities = try Entities(all_components).init(allocator),
             };
         }
 
-    pub fn deinit(world: *World) void {
+        pub fn deinit(world: *Self) void {
             world.systems.deinit(world.allocator);
             world.entities.deinit();
         }
 
-    pub fn register(world: *World, name: []const u8, system: System) !void {
+        pub fn register(world: *Self, name: []const u8, system: System) !void {
             try world.systems.put(world.allocator, name, system);
         }
 
-    pub fn unregister(world: *World, name: []const u8) void {
+        pub fn unregister(world: *Self, name: []const u8) void {
             world.systems.orderedRemove(name);
         }
 
-    pub fn tick(world: *World) void {
+        pub fn tick(world: *Self) void {
             var i: usize = 0;
             while (i < world.systems.count()) : (i += 1) {
                 const system = world.systems.entries.get(i).value;
 
-            var adapter = Adapter{
+                var adapter = Adapter(all_components){
                     .world = world,
                 };
                 system(&adapter);
             }
         }
-};
+    };
+}