use nullable slice for tracking chain allocations

src/browser/Factory.zig

@@ -40,13 +40,6 @@ const Factory = @This();
 _page: *Page,
 _slab: SlabAllocator,
 
-pub const FactoryAllocationKind = union(enum) {
-    /// Allocated as part of a Factory PrototypeChain
-    chain: []u8,
-    /// Allocated standalone via factory.create()
-    standalone,
-};
-
 fn PrototypeChain(comptime types: []const type) type {
     return struct {
         const Self = @This();
@@ -103,7 +96,7 @@ fn PrototypeChain(comptime types: []const type) type {
 
         fn setRoot(self: *const Self, comptime T: type) void {
             const ptr = self.get(0);
-            ptr.* = .{ ._type = unionInit(T, self.get(1)), ._allocation = FactoryAllocationKind{ .chain = self.memory } };
+            ptr.* = .{ ._type = unionInit(T, self.get(1)), ._allocation = self.memory };
         }
 
         fn setMiddle(self: *const Self, comptime index: usize, comptime T: type) void {
@@ -164,7 +157,11 @@ pub fn eventTarget(self: *Factory, child: anytype) !*@TypeOf(child) {
         &.{ EventTarget, @TypeOf(child) },
     ).allocate(allocator);
 
-    chain.setRoot(EventTarget.Type);
+    const event_ptr = chain.get(0);
+    event_ptr.* = .{
+        ._type = unionInit(EventTarget.Type, chain.get(1)),
+        ._allocation = chain.memory,
+    };
     chain.setLeaf(1, child);
 
     return chain.get(1);
@@ -183,7 +180,7 @@ pub fn event(self: *Factory, typ: []const u8, child: anytype) !*@TypeOf(child) {
     event_ptr.* = .{
         ._type = unionInit(Event.Type, chain.get(1)),
         ._type_string = try String.init(self._page.arena, typ, .{}),
-        ._allocation = FactoryAllocationKind{ .chain = chain.memory },
+        ._allocation = chain.memory,
     };
     chain.setLeaf(1, child);
 
@@ -201,7 +198,7 @@ pub fn blob(self: *Factory, child: anytype) !*@TypeOf(child) {
     const blob_ptr = chain.get(0);
     blob_ptr.* = .{
         ._type = unionInit(Blob.Type, chain.get(1)),
-        ._allocation = FactoryAllocationKind{ .chain = chain.memory },
+        ._allocation = chain.memory,
         .slice = "",
         .mime = "",
     };
@@ -295,14 +292,11 @@ pub fn destroy(self: *Factory, value: anytype) void {
         }
     }
 
-    const allocation_kind = self.destroyChain(value, true) orelse return;
+    const chain_memory = self.destroyChain(value, true) orelse return;
-    switch (allocation_kind) {
+    allocator.free(chain_memory);
-        .chain => |buf| allocator.free(buf),
-        .standalone => {},
-    }
 }
 
-fn destroyChain(self: *Factory, value: anytype, comptime first: bool) ?FactoryAllocationKind {
+fn destroyChain(self: *Factory, value: anytype, comptime first: bool) ?[]u8 {
     const S = reflect.Struct(@TypeOf(value));
     const allocator = self._slab.allocator();
 

src/browser/webapi/Blob.zig

@@ -21,14 +21,13 @@ const Writer = std.Io.Writer;
 
 const js = @import("../js/js.zig");
 const Page = @import("../Page.zig");
-const FactoryAllocationKind = @import("../Factory.zig").FactoryAllocationKind;
 
 /// https://w3c.github.io/FileAPI/#blob-section
 /// https://developer.mozilla.org/en-US/docs/Web/API/Blob
 const Blob = @This();
 
 _type: Type,
-_allocation: FactoryAllocationKind,
+_allocation: ?[]u8,
 
 /// Immutable slice of blob.
 /// Note that another blob may hold a pointer/slice to this,
@@ -81,7 +80,7 @@ pub fn init(
 
     return page._factory.create(Blob{
         ._type = .generic,
-        ._allocation = .standalone,
+        ._allocation = null,
         .slice = slice,
         .mime = mime,
     });
@@ -271,7 +270,7 @@ pub fn getSlice(
 
         return page._factory.create(Blob{
             ._type = .generic,
-            ._allocation = .standalone,
+            ._allocation = null,
             .slice = slice[start..end],
             .mime = mime,
         });
@@ -279,7 +278,7 @@ pub fn getSlice(
 
     return page._factory.create(Blob{
         ._type = .generic,
-        ._allocation = .standalone,
+        ._allocation = null,
         .slice = slice,
         .mime = mime,
     });

src/browser/webapi/Event.zig

@@ -20,14 +20,13 @@ const std = @import("std");
 const js = @import("../js/js.zig");
 
 const Page = @import("../Page.zig");
-const FactoryAllocationKind = @import("../Factory.zig").FactoryAllocationKind;
 const EventTarget = @import("EventTarget.zig");
 const String = @import("../../string.zig").String;
 
 pub const Event = @This();
 
 _type: Type,
-_allocation: FactoryAllocationKind,
+_allocation: ?[]u8,
 
 _bubbles: bool = false,
 _cancelable: bool = false,
@@ -68,7 +67,7 @@ pub fn init(typ: []const u8, opts_: ?Options, page: *Page) !*Event {
 
     return page._factory.create(Event{
         ._type = .generic,
-        ._allocation = .standalone,
+        ._allocation = null,
         ._bubbles = opts.bubbles,
         ._time_stamp = time_stamp,
         ._cancelable = opts.cancelable,

src/browser/webapi/EventTarget.zig

@@ -21,14 +21,13 @@ const js = @import("../js/js.zig");
 
 const Page = @import("../Page.zig");
 const RegisterOptions = @import("../EventManager.zig").RegisterOptions;
-const FactoryAllocationKind = @import("../Factory.zig").FactoryAllocationKind;
 
 const Event = @import("Event.zig");
 
 const EventTarget = @This();
 
 _type: Type,
-_allocation: FactoryAllocationKind,
+_allocation: ?[]u8,
 
 pub const Type = union(enum) {
     node: *@import("Node.zig"),
@@ -124,7 +123,7 @@ pub const JsApi = struct {
 const testing = @import("../../testing.zig");
 test "WebApi: EventTarget" {
     // we create thousands of these per page. Nothing should bloat it.
-    try testing.expectEqual(16, @sizeOf(EventTarget));
+    try testing.expectEqual(32, @sizeOf(EventTarget));
 
     try testing.htmlRunner("events.html", .{});
 }