mach: check Platform functions declaration & add deinit for wasm

src/platform.zig

@@ -1,7 +1,41 @@
 const builtin = @import("builtin");
 
-const Platform = if (builtin.cpu.arch == .wasm32) @import("platform/wasm.zig") else @import("platform/native.zig");
+const Platform = if (builtin.cpu.arch == .wasm32)
+    Interface(@import("platform/wasm.zig"))
+else
+    Interface(@import("platform/native.zig"));
 
-// TODO: verify declarations and its signatures
 pub const Type = Platform.Platform;
 pub const BackingTimerType = Platform.BackingTimer;
+
+/// Verifies that a Platform implementation exposes the expected function declarations.
+fn Interface(comptime T: type) type {
+    assertHasDecl(T, "Platform");
+    assertHasDecl(T, "BackingTimer");
+    assertHasDecl(T.Platform, "init");
+    assertHasDecl(T.Platform, "deinit");
+    assertHasDecl(T.Platform, "setOptions");
+    assertHasDecl(T.Platform, "close");
+    assertHasDecl(T.Platform, "setWaitEvent");
+    assertHasDecl(T.Platform, "getFramebufferSize");
+    assertHasDecl(T.Platform, "getWindowSize");
+    assertHasDecl(T.Platform, "setMouseCursor");
+    assertHasDecl(T.Platform, "hasEvent");
+    assertHasDecl(T.Platform, "pollEvent");
+    assertHasDecl(T.BackingTimer, "start");
+    assertHasDecl(T.BackingTimer, "read");
+    assertHasDecl(T.BackingTimer, "reset");
+    assertHasDecl(T.BackingTimer, "lap");
+
+    return T;
+}
+
+fn assertDecl(comptime T: anytype, comptime name: []const u8, comptime Decl: type) void {
+    assertHasDecl(T, name);
+    const FoundDecl = @TypeOf(@field(T, name));
+    if (FoundDecl != Decl) @compileError("Platform field '" ++ name ++ "'\n\texpected type: " ++ @typeName(Decl) ++ "\n\t   found type: " ++ @typeName(FoundDecl));
+}
+
+fn assertHasDecl(comptime T: anytype, comptime name: []const u8) void {
+    if (!@hasDecl(T, name)) @compileError("Platform missing declaration: " ++ name);
+}

src/platform/wasm.zig

@@ -43,6 +43,7 @@ pub const CanvasId = u32;
 pub const Platform = struct {
     id: CanvasId,
     selector_id: []const u8,
+    allocator: std.mem.Allocator,
 
     last_window_size: structs.Size,
     last_framebuffer_size: structs.Size,
@@ -57,6 +58,7 @@ pub const Platform = struct {
         var platform = Platform{
             .id = id,
             .selector_id = try allocator.dupe(u8, selector[0 .. selector.len - @as(u32, if (selector[selector.len - 1] == 0) 1 else 0)]),
+            .allocator = allocator,
             .last_window_size = .{
                 .width = js.machCanvasGetWindowWidth(id),
                 .height = js.machCanvasGetWindowHeight(id),
@@ -85,6 +87,11 @@ pub const Platform = struct {
         return platform;
     }
 
+    pub fn deinit(platform: *Platform) void {
+        js.machCanvasDeinit(platform.id);
+        platform.allocator.free(platform.selector_id);
+    }
+
     pub fn setOptions(platform: *Platform, options: structs.Options) !void {
         // NOTE: size limits do not exists on wasm
         js.machCanvasSetSize(platform.id, options.width, options.height);
@@ -302,6 +309,7 @@ export fn wasmUpdate() void {
 
 export fn wasmDeinit() void {
     app.deinit(&core);
+    core.internal.deinit();
 }
 
 pub const log_level = if (@hasDecl(App, "log_level")) App.log_level else std.log.default_level;