Merge pull request #294 from karlseguin/remote_object_subtype

Add RemoteObject subtype

Author: krichprollsch

build.zig

@@ -182,7 +182,7 @@ pub fn packages(comptime vendor_path: []const u8) type {
             mod.addIncludePath(b.path(vendor ++ "/zig-v8/src"));
 
             const build_opts = b.addOptions();
-            build_opts.addOption(bool, "inspector_subtype", true);
+            build_opts.addOption(bool, "inspector_subtype", false);
             mod.addOptions("default_exports", build_opts);
             return mod;
         }

src/engines/v8/generate.zig

@@ -34,6 +34,7 @@ const jsToObject = @import("types_primitives.zig").jsToObject;
 const TPL = @import("v8.zig").TPL;
 const JSObject = @import("v8.zig").JSObject;
 const JSObjectID = @import("v8.zig").JSObjectID;
+const ExternalEntry = @import("v8.zig").ExternalEntry;
 
 // Utils functions
 // ---------------
@@ -435,20 +436,17 @@ fn bindObjectNativeToJS(
     const pers = PersistentObject.init(isolate, js_obj);
     const js_obj_pers = pers.castToObject();
 
-    // bind the native object pointer to the JS object
-    var ext: v8.External = undefined;
-    if (comptime T_refl.is_mem_guarantied()) {
-
-        // store directly the object pointer
-        ext = v8.External.init(isolate, nat_obj);
-    } else {
+    const entry = try alloc.create(ExternalEntry);
+    entry.* = .{
+        .ptr = nat_obj,
+        .sub_type = T_refl.sub_type,
+    };
 
-        // use the refs mechanism
-        const int_ptr = try alloc.create(usize);
-        int_ptr.* = @intFromPtr(nat_obj);
-        ext = v8.External.init(isolate, int_ptr);
-        try nat_ctx.nat_objs.put(alloc, int_ptr.*, T_refl.index);
+    // bind the native object pointer to the JS object
+    if (comptime T_refl.is_mem_guarantied() == false) {
+        try nat_ctx.nat_objs.put(alloc, @intFromPtr(nat_obj), T_refl.index);
     }
+    const ext = v8.External.init(isolate, entry);
     js_obj_pers.setInternalField(0, ext);
     return js_obj_pers;
 }
@@ -824,12 +822,14 @@ fn getNativeObject(
 
         // TODO ensure the js object corresponds to the expected native type.
 
-        const ext = js_obj.getInternalField(0).castTo(v8.External).get().?;
+        const external_data = js_obj.getInternalField(0).castTo(v8.External).get().?;
+        const external_entry: *ExternalEntry = @alignCast(@ptrCast(external_data));
+        const opaque_instance_ptr = external_entry.ptr;
         if (comptime T_refl.is_mem_guarantied()) {
             // memory is fixed
             // ensure the pointer is aligned (no-op at runtime)
             // as External is a ?*anyopaque (ie. *void) with alignment 1
-            const ptr: *align(@alignOf(T_refl.Self())) anyopaque = @alignCast(ext);
+            const ptr: *align(@alignOf(T_refl.Self())) anyopaque = @alignCast(opaque_instance_ptr);
             if (@hasDecl(T_refl.T, "protoCast")) {
                 // T_refl provides a function to cast the pointer from high level Type
                 obj_ptr = @call(.auto, @field(T_refl.T, "protoCast"), .{ptr});
@@ -841,7 +841,7 @@ fn getNativeObject(
             }
         } else {
             // use the refs mechanism to retrieve from high level Type
-            obj_ptr = try refs.getObject(nat_ctx.nat_objs, T, gen.Types, ext);
+            obj_ptr = try refs.getObject(nat_ctx.nat_objs, T, gen.Types, opaque_instance_ptr);
         }
     }
     return obj_ptr;

src/engines/v8/v8.zig

@@ -720,3 +720,59 @@ pub const Inspector = struct {
         return self.session.dispatchProtocolMessage(env.isolate, msg);
     }
 };
+
+// When we return a Zig instance to V8, we wrap it in a v8.Object. That wrapping
+// happens by:
+//  - Assigning our instance to a v8.External (which just holds an *anyopaque)
+//  - Creating a v8.PersistentObject and assigning the external to the
+//    PersistentObject's internalField #0
+//  - Casting the v8.PersistentObject to a v8.Object
+//
+// Now, instead of assigning the instance directly into the v8.External we
+// allocate and assign this ExternalEntry, which allows us to hold the ptr to
+// the Zig instance, as well as meta data that we'll need.
+pub const ExternalEntry = struct {
+    // Ptr to the Zig instance
+    ptr: *anyopaque,
+
+    // When we're asked to describe an object via the Inspector, we _must_ include
+    // the proper subtype (and description) fields in the returned JSON.
+    // V8 will give us a Value and ask us for the subtype. Hence, we store it
+    // here.
+    sub_type: ?[*c]const u8,
+};
+
+// See above for documentation for the ExternalEntry's sub_type field.
+pub export fn v8_inspector__Client__IMPL__valueSubtype(
+    _: *v8.c.InspectorClientImpl,
+    c_value: *const v8.C_Value,
+) callconv(.C) [*c]const u8 {
+    const external_entry = getExternalEntry(.{ .handle = c_value }) orelse return null;
+    return if (external_entry.sub_type) |st| st else null;
+}
+
+pub export fn v8_inspector__Client__IMPL__descriptionForValueSubtype(
+    _: *v8.c.InspectorClientImpl,
+    context: *const v8.C_Context,
+    c_value: *const v8.C_Value,
+) callconv(.C) [*c]const u8 {
+    _ = context;
+
+    // We _must_ include a non-null description in order for the subtype value
+    // to be included. Besides that, I don't know if the value has any meaning
+    const external_entry = getExternalEntry(.{ .handle = c_value }) orelse return null;
+    return if (external_entry.sub_type == null) null else "";
+}
+
+fn getExternalEntry(value: v8.Value) ?*ExternalEntry {
+    if (value.isObject() == false) {
+        return null;
+    }
+    const obj = value.castTo(Object);
+    if (obj.internalFieldCount() == 0) {
+        return null;
+    }
+
+    const external_data = obj.getInternalField(0).castTo(v8.External).get().?;
+    return @alignCast(@ptrCast(external_data));
+}

src/reflect.zig

@@ -785,6 +785,7 @@ pub const Struct = struct {
 
     // nested types
     nested: []const StructNested,
+    sub_type: ?[*c]const u8,
 
     pub fn Self(comptime self: Struct) type {
         comptime {
@@ -1246,6 +1247,11 @@ pub const Struct = struct {
             mem_guarantied = @typeInfo(T).@"struct".layout != .auto;
         }
 
+        var sub_type: ?[*c]const u8 = null;
+        if (@hasDecl(T, "sub_type")) {
+            sub_type = @field(T, "sub_type");
+        }
+
         // nested types
         var nested_nb: usize = 0;
         // first iteration to retrieve the number of nested structs
@@ -1430,6 +1436,7 @@ pub const Struct = struct {
 
             // nested types
             .nested = &cnested,
+            .sub_type = sub_type,
         };
     }
 };

src/refs.zig

@@ -26,11 +26,8 @@ const refl = internal.refl;
 pub const Map = std.AutoHashMapUnmanaged(usize, usize);
 
 pub fn getObject(map: Map, comptime T: type, comptime types: []const refl.Struct, ptr: anytype) !*T {
-
-    // use the object pointer (key) to retrieve the API index (value) in the map
-    const ptr_aligned: *align(@alignOf(usize)) anyopaque = @alignCast(ptr);
-    const key: *usize = @ptrCast(ptr_aligned);
-    const T_index = map.get(key.*);
+    const key: usize = @intFromPtr(ptr);
+    const T_index = map.get(key);
     if (T_index == null) {
         return error.NullReference;
     }
@@ -42,7 +39,7 @@ pub fn getObject(map: Map, comptime T: type, comptime types: []const refl.Struct
             if (!T_refl.isEmpty()) { // stage1: condition is needed for empty structs
                 // go through the "proto" object chain
                 // to retrieve the good object corresponding to T
-                const target_ptr: *T_refl.Self() = @ptrFromInt(key.*);
+                const target_ptr: *T_refl.Self() = @ptrFromInt(key);
                 return try getRealObject(T, target_ptr);
             }
         }