core: simplify event iterator

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

examples/core/custom-entrypoint/App.zig

@@ -71,8 +71,7 @@ fn init(app: *Mod, core: *mach.Core.Mod) !void {
 }
 
 fn tick(core: *mach.Core.Mod, app: *Mod) !void {
-    var iter = core.state().pollEvents();
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .close => core.schedule(.exit), // Tell mach.Core to exit the app
             else => {},

examples/core/triangle/App.zig

@@ -71,8 +71,7 @@ fn init(app: *Mod, core: *mach.Core.Mod) !void {
 }
 
 fn tick(core: *mach.Core.Mod, app: *Mod) !void {
-    var iter = core.state().pollEvents();
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .close => core.schedule(.exit), // Tell mach.Core to exit the app
             else => {},

examples/custom-renderer/App.zig

@@ -96,10 +96,9 @@ fn tick(
     renderer: *Renderer.Mod,
     app: *Mod,
 ) !void {
-    var iter = core.state().pollEvents();
     var direction = app.state().direction;
     var spawning = app.state().spawning;
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| {
                 switch (ev.key) {

examples/glyphs/App.zig

@@ -110,12 +110,9 @@ fn tick(
     glyphs: *Glyphs.Mod,
     app: *Mod,
 ) !void {
-    // TODO(important): event polling should occur in mach.Core module and get fired as ECS events.
-    // TODO(Core)
-    var iter = core.state().pollEvents();
     var direction = app.state().direction;
     var spawning = app.state().spawning;
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| {
                 switch (ev.key) {

examples/hardware-check/App.zig

@@ -185,9 +185,8 @@ fn tick(
 ) !void {
     // TODO(important): event polling should occur in mach.Core module and get fired as ECS events.
     // TODO(Core)
-    var iter = core.state().pollEvents();
     var gotta_go_fast = app.state().gotta_go_fast;
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| {
                 switch (ev.key) {

examples/piano/App.zig

@@ -104,9 +104,7 @@ fn tick(
     audio: *mach.Audio.Mod,
     app: *Mod,
 ) !void {
-    // TODO(Core)
-    var iter = core.state().pollEvents();
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| {
                 switch (ev.key) {

examples/play-opus/App.zig

@@ -118,9 +118,7 @@ fn tick(
     audio: *mach.Audio.Mod,
     app: *Mod,
 ) !void {
-    // TODO(Core)
-    var iter = core.state().pollEvents();
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| switch (ev.key) {
                 .down => {

examples/sprite/App.zig

@@ -114,12 +114,9 @@ fn tick(
     sprite_pipeline: *gfx.SpritePipeline.Mod,
     app: *Mod,
 ) !void {
-    // TODO(important): event polling should occur in mach.Core module and get fired as ECS events.
-    // TODO(Core)
-    var iter = core.state().pollEvents();
     var direction = app.state().direction;
     var spawning = app.state().spawning;
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| {
                 switch (ev.key) {

examples/text/App.zig

@@ -125,12 +125,9 @@ fn tick(
     text_pipeline: *gfx.TextPipeline.Mod,
     app: *Mod,
 ) !void {
-    // TODO(important): event polling should occur in mach.Core module and get fired as ECS events.
-    // TODO(Core)
-    var iter = core.state().pollEvents();
     var direction = app.state().direction;
     var spawning = app.state().spawning;
-    while (iter.next()) |event| {
+    while (core.state().nextEvent()) |event| {
         switch (event) {
             .key_press => |ev| {
                 switch (ev.key) {

src/Core.zig

@@ -23,15 +23,7 @@ pub const supports_non_blocking = switch (build_options.core_platform) {
     .null => true,
 };
 
-pub const EventQueue = std.fifo.LinearFifo(Event, .Dynamic);
-
-pub const EventIterator = struct {
-    queue: *EventQueue,
-
-    pub fn next(self: *EventIterator) ?Event {
-        return self.queue.readItem();
-    }
-};
+const EventQueue = std.fifo.LinearFifo(Event, .Dynamic);
 
 /// Set this to true if you intend to drive the main loop yourself.
 ///
@@ -126,8 +118,10 @@ pub const components = .{
     },
 };
 
-// Callback systems
+/// Callback system invoked per tick (e.g. per-frame)
 on_tick: ?mach.AnySystem = null,
+
+/// Callback system invoked when application is exiting
 on_exit: ?mach.AnySystem = null,
 
 allocator: std.mem.Allocator,
@@ -156,6 +150,9 @@ surface: *gpu.Surface,
 swap_chain: *gpu.SwapChain,
 descriptor: gpu.SwapChain.Descriptor,
 
+// Internal state
+events: EventQueue,
+
 // TODO: this needs to be removed.
 pub const InitOptions = struct {
     allocator: std.mem.Allocator,
@@ -200,9 +197,13 @@ fn init(core: *Mod, entities: *mach.Entities.Mod) !void {
         title[options.title.len] = 0;
     }
 
+    var events = EventQueue.init(allocator);
+    try events.ensureTotalCapacity(8192);
+
     core.init(.{
         .allocator = allocator,
         .main_window = main_window,
+        .events = events,
 
         // TODO: remove undefined initialization (disgusting!)
         .platform = undefined,
@@ -220,7 +221,8 @@ fn init(core: *Mod, entities: *mach.Entities.Mod) !void {
         .descriptor = undefined,
     });
     const state = core.state();
-    try Platform.init(&state.platform, options);
+
+    try Platform.init(&state.platform, core, options);
 
     state.instance = gpu.createInstance(null) orelse {
         log.err("failed to create GPU instance", .{});
@@ -386,6 +388,7 @@ pub fn deinit(entities: *mach.Entities.Mod, core: *Mod) !void {
     state.surface.release();
     state.adapter.release();
     state.instance.release();
+    state.events.deinit();
 }
 
 pub const InputState = struct {
@@ -602,8 +605,10 @@ pub const KeyMods = packed struct(u8) {
     _padding: u2 = 0,
 };
 
-pub inline fn pollEvents(core: *@This()) EventIterator {
-    return .{ .platform = core.platform.pollEvents() };
+/// Returns the next event until there are no more available. You should check for events during
+/// every on_tick()
+pub inline fn nextEvent(core: *@This()) ?Event {
+    return core.events.readItem();
 }
 
 /// Sets the window title. The string must be owned by Core, and will not be copied or freed. It is
@@ -1063,7 +1068,6 @@ comptime {
 
     assertHasDecl(Platform, "init");
     assertHasDecl(Platform, "deinit");
-    assertHasDecl(Platform, "pollEvents");
 
     assertHasDecl(Platform, "setTitle");
 
@@ -1104,10 +1108,8 @@ fn assertHasField(comptime T: anytype, comptime field_name: []const u8) void {
 }
 
 test {
-    @import("std").testing.refAllDecls(Platform);
-
+    _ = Platform;
     @import("std").testing.refAllDeclsRecursive(InitOptions);
-    @import("std").testing.refAllDeclsRecursive(EventIterator);
     @import("std").testing.refAllDeclsRecursive(VSyncMode);
     @import("std").testing.refAllDeclsRecursive(Size);
     @import("std").testing.refAllDeclsRecursive(Position);

src/core/Darwin.zig

@@ -23,11 +23,7 @@ pub const Darwin = @This();
 
 allocator: std.mem.Allocator,
 core: *Core,
-
-events: Core.EventQueue,
 input_state: Core.InputState,
-// modifiers: KeyMods,
-
 title: [:0]const u8,
 display_mode: DisplayMode,
 vsync_mode: VSyncMode,
@@ -72,7 +68,12 @@ pub fn run(comptime on_each_update_fn: anytype, args_tuple: std.meta.ArgsTuple(@
 }
 
 // Called on the main thread
-pub fn init(darwin: *Darwin, options: InitOptions) !void {
+pub fn init(
+    darwin: *Darwin,
+    core: *Core.Mod,
+    options: InitOptions,
+) !void {
+    _ = core;
     var surface_descriptor = gpu.Surface.Descriptor{};
 
     // TODO: support UIKit.
@@ -106,13 +107,9 @@ pub fn init(darwin: *Darwin, options: InitOptions) !void {
         window.?.makeKeyAndOrderFront(null);
     }
 
-    var events = EventQueue.init(options.allocator);
-    try events.ensureTotalCapacity(2048);
-
     darwin.* = .{
         .allocator = options.allocator,
         .core = @fieldParentPtr("platform", darwin),
-        .events = events,
         .input_state = .{},
         .title = options.title,
         .display_mode = options.display_mode,
@@ -138,11 +135,6 @@ pub fn update(_: *Darwin) !void {
     return;
 }
 
-// May be called from any thread.
-pub inline fn pollEvents(n: *Darwin) Core.EventIterator {
-    return .{ .queue = &n.events };
-}
-
 // May be called from any thread.
 pub fn setTitle(_: *Darwin, _: [:0]const u8) void {
     return;

src/core/Null.zig

@@ -25,11 +25,8 @@ pub const Null = @This();
 
 allocator: std.mem.Allocator,
 core: *Core,
-
-events: Core.EventQueue,
 input_state: Core.InputState,
 modifiers: KeyMods,
-
 title: [:0]u8,
 display_mode: DisplayMode,
 vsync_mode: VSyncMode,
@@ -42,7 +39,14 @@ size: Size,
 surface_descriptor: gpu.Surface.Descriptor,
 
 // Called on the main thread
-pub fn init(_: *Null, _: InitOptions) !void {
+pub fn init(
+    nul: *Null,
+    core: *Core.Mod,
+    options: InitOptions,
+) !void {
+    _ = nul;
+    _ = options;
+    _ = core;
     return;
 }
 
@@ -55,11 +59,6 @@ pub fn update(_: *Null) !void {
     return;
 }
 
-// May be called from any thread.
-pub inline fn pollEvents(n: *Null) Core.EventIterator {
-    return .{ .queue = &n.events };
-}
-
 // May be called from any thread.
 pub fn setTitle(_: *Null, _: [:0]const u8) void {
     return;

src/core/Windows.zig

@@ -44,7 +44,7 @@ surrogate: u16 = 0,
 dinput: *w.IDirectInput8W,
 saved_window_rect: w.RECT,
 surface_descriptor_from_hwnd: gpu.Surface.DescriptorFromWindowsHWND,
-events: EventQueue,
+state: *Core,
 input_state: Core.InputState,
 oom: std.Thread.ResetEvent = .{},
 
@@ -53,11 +53,12 @@ oom: std.Thread.ResetEvent = .{},
 // ------------------------------
 pub fn init(
     self: *Win32,
+    core: *Core.Mod,
     options: InitOptions,
 ) !void {
+    self.state = core.state();
     self.allocator = options.allocator;
     self.core = @fieldParentPtr("platform", self);
-    self.events = EventQueue.init(self.allocator);
     self.size = options.size;
     self.input_state = .{};
     self.saved_window_rect = .{ .top = 0, .left = 0, .right = 0, .bottom = 0 };
@@ -138,7 +139,6 @@ pub fn init(
 }
 
 pub fn deinit(self: *Win32) void {
-    self.events.deinit();
     _ = self.dinput.IUnknown_Release();
 }
 
@@ -151,10 +151,6 @@ pub fn update(self: *Win32) !void {
     }
 }
 
-pub fn pollEvents(self: *Win32) EventIterator {
-    return .{ .queue = &self.events };
-}
-
 pub fn setTitle(self: *Win32, title: [:0]const u8) void {
     const wtitle = std.unicode.utf8ToUtf16LeAllocZ(self.allocator, title) catch {
         self.oom.set();
@@ -316,7 +312,7 @@ pub fn outOfMemory(self: *Win32) bool {
 }
 
 fn pushEvent(self: *Win32, event: Event) void {
-    self.events.writeItem(event) catch self.oom.set();
+    self.state.events.writeItem(event) catch self.oom.set();
 }
 
 fn getKeyboardModifiers() mach.Core.KeyMods {