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merged 2 commits into from
Nov 20, 2025
Merged

JS API table changes for zigdom #1225

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1aca22f
JS API table changes for zigdom
nikneym Nov 20, 2025
629297e
uncomment the assertion
nikneym Nov 20, 2025
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15 changes: 6 additions & 9 deletions src/browser/js/Context.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -457,8 +457,7 @@ pub fn zigValueToJs(self: *Context, value: anytype, comptime opts: Caller.CallOp
.pointer => |ptr| switch (ptr.size) {
.one => {
if (@typeInfo(ptr.child) == .@"struct" and @hasDecl(ptr.child, "JsApi")) {
const type_name = @typeName(ptr.child.JsApi);
if (@hasField(bridge.JsApiLookup, type_name)) {
if (bridge.JsApiLookup.has(ptr.child.JsApi)) {
const js_obj = try self.mapZigInstanceToJs(null, value);
return js_obj.toValue();
}
Expand Down Expand Up @@ -499,8 +498,7 @@ pub fn zigValueToJs(self: *Context, value: anytype, comptime opts: Caller.CallOp
},
.@"struct" => |s| {
if (@hasDecl(T, "JsApi")) {
const type_name = @typeName(T.JsApi);
if (@hasField(bridge.JsApiLookup, type_name)) {
if (bridge.JsApiLookup.has(T.JsApi)) {
const js_obj = try self.mapZigInstanceToJs(null, value);
return js_obj.toValue();
}
Expand Down Expand Up @@ -707,7 +705,7 @@ pub fn jsValueToZig(self: *Context, comptime T: type, js_value: v8.Value) !T {
return error.InvalidArgument;
}
if (@hasDecl(ptr.child, "JsApi")) {
std.debug.assert(@hasField(bridge.JsApiLookup, @typeName(ptr.child.JsApi)));
std.debug.assert(bridge.JsApiLookup.has(ptr.child.JsApi));
const js_obj = js_value.castTo(v8.Object);
return typeTaggedAnyOpaque(*ptr.child, js_obj);
}
Expand Down Expand Up @@ -1537,14 +1535,13 @@ pub fn typeTaggedAnyOpaque(comptime R: type, js_obj: v8.Object) !R {
return error.InvalidArgument;
}

const type_name = @typeName(JsApi);
if (@hasField(bridge.JsApiLookup, type_name) == false) {
if (!bridge.JsApiLookup.has(JsApi)) {
@compileError("unknown Zig type: " ++ @typeName(R));
}

const op = js_obj.getInternalField(0).castTo(v8.External).get();
const tao: *TaggedAnyOpaque = @ptrCast(@alignCast(op));
const expected_type_index = @field(bridge.JS_API_LOOKUP, type_name);
const expected_type_index = bridge.JsApiLookup.getId(JsApi);

const prototype_chain = tao.prototype_chain[0..tao.prototype_len];
if (prototype_chain[0].index == expected_type_index) {
Expand Down Expand Up @@ -1643,7 +1640,7 @@ fn probeJsValueToZig(self: *Context, comptime T: type, js_value: v8.Value) !Prob
if (!js_value.isObject()) {
return .{ .invalid = {} };
}
if (@hasField(bridge.JsApiLookup, @typeName(ptr.child.JsApi))) {
if (bridge.JsApiLookup.has(ptr.child.JsApi)) {
const js_obj = js_value.castTo(v8.Object);
// There's a bit of overhead in doing this, so instead
// of having a version of typeTaggedAnyOpaque which
Expand Down
4 changes: 2 additions & 2 deletions src/browser/js/Env.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -335,7 +335,7 @@ fn generateConstructor(comptime JsApi: type, isolate: v8.Isolate) v8.FunctionTem
// }
// }

pub fn protoIndexLookup(comptime JsApi: type) ?u16 {
pub fn protoIndexLookup(comptime JsApi: type) ?bridge.JsApiLookup.BackingInt {
@setEvalBranchQuota(2000);
comptime {
const T = JsApi.bridge.type;
Expand All @@ -344,6 +344,6 @@ pub fn protoIndexLookup(comptime JsApi: type) ?u16 {
}
const Ptr = std.meta.fieldInfo(T, ._proto).type;
const F = @typeInfo(Ptr).pointer.child;
return @field(bridge.JS_API_LOOKUP, @typeName(F.JsApi));
return bridge.JsApiLookup.getId(F.JsApi);
}
}
2 changes: 1 addition & 1 deletion src/browser/js/ExecutionWorld.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,7 @@ pub fn createContext(self: *ExecutionWorld, page: *Page, enter: bool, global_cal
// specific instance of the the Window.
{
const proto_type = @typeInfo(@TypeOf(page.window._proto)).pointer.child;
const proto_index = @field(bridge.JS_API_LOOKUP, @typeName(proto_type.JsApi));
const proto_index = bridge.JsApiLookup.getId(proto_type.JsApi);
js_global.inherit(templates[proto_index]);
}

Expand Down
120 changes: 67 additions & 53 deletions src/browser/js/bridge.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -64,20 +64,17 @@ pub fn Builder(comptime T: type) type {
pub fn prototypeChain() [prototypeChainLength(T)]js.PrototypeChainEntry {
var entries: [prototypeChainLength(T)]js.PrototypeChainEntry = undefined;

entries[0] = .{
.offset = 0,
.index = @field(JS_API_LOOKUP, @typeName(T.JsApi)),
};
entries[0] = .{ .offset = 0, .index = JsApiLookup.getId(T.JsApi) };

if (entries.len == 1) {
return entries;
}

var Prototype = T;
for (entries[1..]) |*entry| {
inline for (entries[1..]) |*entry| {
const Next = PrototypeType(Prototype).?;
entry.* = .{
.index = @field(JS_API_LOOKUP, @typeName(Next.JsApi)),
.index = JsApiLookup.getId(Next.JsApi),
.offset = @offsetOf(Prototype, "_proto"),
};
Prototype = Next;
Expand Down Expand Up @@ -394,55 +391,72 @@ pub fn Struct(comptime T: type) type {
};
}

// Imagine we have a type Cat which has a getter:
//
// fn getOwner(self: *Cat) *Owner {
// return self.owner;
// }
//
// When we execute caller.getter, we'll end up doing something like:
// const res = @call(.auto, Cat.getOwner, .{cat_instance});
//
// How do we turn `res`, which is an *Owner, into something we can return
// to v8? We need the ObjectTemplate associated with Owner. How do we
// get that? Well, we store all the ObjectTemplates in an array that's
// tied to env. So we do something like:
//
// env.templates[index_of_owner].initInstance(...);
//
// But how do we get that `index_of_owner`? `Lookup` is a struct
// that looks like:
//
// const Lookup = struct {
// comptime cat: usize = 0,
// comptime owner: usize = 1,
// ...
// }
//
// So to get the template index of `owner`, we can do:
//
// const index_id = @field(type_lookup, @typeName(@TypeOf(res));
//
pub const JsApiLookup = blk: {
var fields: [JsApis.len]std.builtin.Type.StructField = undefined;
for (JsApis, 0..) |JsApi, i| {
fields[i] = .{
.name = @typeName(JsApi),
.type = u16,
.is_comptime = true,
.alignment = @alignOf(u16),
.default_value_ptr = @ptrCast(&i),
};
pub const JsApiLookup = struct {
/// Integer type we use for `JsApiLookup` enum. Can be u8 at min.
pub const BackingInt = std.math.IntFittingRange(0, @max(std.math.maxInt(u8), JsApis.len));

/// Imagine we have a type `Cat` which has a getter:
///
/// fn get_owner(self: *Cat) *Owner {
/// return self.owner;
/// }
///
/// When we execute `caller.getter`, we'll end up doing something like:
///
/// const res = @call(.auto, Cat.get_owner, .{cat_instance});
///
/// How do we turn `res`, which is an *Owner, into something we can return
/// to v8? We need the ObjectTemplate associated with Owner. How do we
/// get that? Well, we store all the ObjectTemplates in an array that's
/// tied to env. So we do something like:
///
/// env.templates[index_of_owner].initInstance(...);
///
/// But how do we get that `index_of_owner`? `Index` is an enum
/// that looks like:
///
/// pub const Enum = enum(BackingInt) {
/// cat = 0,
/// owner = 1,
/// ...
/// }
///
/// (`BackingInt` is calculated at comptime regarding to interfaces we have)
/// So to get the template index of `owner`, simply do:
///
/// const index_id = types.getId(@TypeOf(res));
///
pub const Enum = blk: {
var fields: [JsApis.len]std.builtin.Type.EnumField = undefined;
for (JsApis, 0..) |JsApi, i| {
fields[i] = .{ .name = @typeName(JsApi), .value = i };
}

break :blk @Type(.{
.@"enum" = .{
.fields = &fields,
.tag_type = BackingInt,
.is_exhaustive = true,
.decls = &.{},
},
});
};

/// Returns a boolean indicating if a type exist in the lookup.
pub inline fn has(t: type) bool {
return @hasField(Enum, @typeName(t));
}
break :blk @Type(.{ .@"struct" = .{
.layout = .auto,
.decls = &.{},
.is_tuple = false,
.fields = &fields,
} });
};

pub const JS_API_LOOKUP = JsApiLookup{};
/// Returns the `Enum` for the given type.
pub inline fn getIndex(t: type) Enum {
return @field(Enum, @typeName(t));
}

/// Returns the ID for the given type.
pub inline fn getId(t: type) BackingInt {
return @intFromEnum(getIndex(t));
}
};

pub const SubType = enum {
@"error",
Expand Down
2 changes: 1 addition & 1 deletion src/browser/js/js.zig
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Expand Up @@ -478,7 +478,7 @@ pub const TaggedAnyOpaque = struct {
};

pub const PrototypeChainEntry = struct {
index: u16,
index: bridge.JsApiLookup.BackingInt,
offset: u16, // offset to the _proto field
};

Expand Down
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