Merge pull request #577 from lightpanda-io/unified_intrusive_events

Unify the Zig and JS events using an intrusive node.

src/browser/browser.zig

@@ -229,6 +229,8 @@ pub const Page = struct {
 
     renderer: FlatRenderer,
 
+    window_clicked_event_node: parser.EventNode,
+
     scope: *Env.Scope,
 
     // current_script is the script currently evaluated by the page.
@@ -245,6 +247,7 @@ pub const Page = struct {
             .url = URL.empty,
             .session = session,
             .renderer = FlatRenderer.init(arena),
+             .window_clicked_event_node = .{ .func = windowClicked },
             .state = .{
                 .arena = arena,
                 .document = null,
@@ -400,12 +403,10 @@ pub const Page = struct {
         self.doc = doc;
 
         const document_element = (try parser.documentGetDocumentElement(doc)) orelse return error.DocumentElementError;
-        try parser.eventTargetAddZigListener(
+        try parser.eventTargetAddEventListener(
             parser.toEventTarget(parser.Element, document_element),
-            arena,
             "click",
-            windowClicked,
-            self,
+            &self.window_clicked_event_node,
             false,
         );
 
@@ -675,8 +676,8 @@ pub const Page = struct {
         _ = try parser.elementDispatchEvent(element, @ptrCast(event));
     }
 
-    fn windowClicked(ctx: *anyopaque, event: *parser.Event) void {
-        const self: *Page = @alignCast(@ptrCast(ctx));
+    fn windowClicked(node: *parser.EventNode, event: *parser.Event) void {
+        const self: *Page = @fieldParentPtr("window_clicked_event_node", node);
         self._windowClicked(event) catch |err| {
             log.err("window click handler: {}", .{err});
         };

src/browser/dom/event_target.zig

@@ -46,7 +46,7 @@ pub const EventTarget = struct {
 
     pub fn _addEventListener(
         self: *parser.EventTarget,
-        eventType: []const u8,
+        typ: []const u8,
         cbk: Env.Callback,
         capture: ?bool,
         state: *SessionState,
@@ -56,7 +56,7 @@ pub const EventTarget = struct {
         // check if event target has already this listener
         const lst = try parser.eventTargetHasListener(
             self,
-            eventType,
+            typ,
             capture orelse false,
             cbk.id,
         );
@@ -64,29 +64,28 @@ pub const EventTarget = struct {
             return;
         }
 
+        const eh = try EventHandler.init(state.arena, try cbk.withThis(self));
+
         try parser.eventTargetAddEventListener(
             self,
-            state.arena,
-            eventType,
-            EventHandler,
-            .{ .cbk = cbk },
+            typ,
+            &eh.node,
             capture orelse false,
         );
     }
 
     pub fn _removeEventListener(
         self: *parser.EventTarget,
-        eventType: []const u8,
+        typ: []const u8,
         cbk: Env.Callback,
         capture: ?bool,
-        state: *SessionState,
         // TODO: hanle EventListenerOptions
         // see #https://github.com/lightpanda-io/jsruntime-lib/issues/114
     ) !void {
         // check if event target has already this listener
         const lst = try parser.eventTargetHasListener(
             self,
-            eventType,
+            typ,
             capture orelse false,
             cbk.id,
         );
@@ -97,8 +96,7 @@ pub const EventTarget = struct {
         // remove listener
         try parser.eventTargetRemoveEventListener(
             self,
-            state.arena,
-            eventType,
+            typ,
             lst.?,
             capture orelse false,
         );

src/browser/dom/mutation_observer.zig

@@ -59,56 +59,45 @@ pub const MutationObserver = struct {
             .node = node,
             .options = options,
             .mutation_observer = self,
+            .event_node = .{ .id = self.cbk.id, .func = Observer.handle },
         };
 
-        const arena = self.arena;
-
         // register node's events
         if (options.childList or options.subtree) {
-            try parser.eventTargetAddZigListener(
+            try parser.eventTargetAddEventListener(
                 parser.toEventTarget(parser.Node, node),
-                arena,
                 "DOMNodeInserted",
-                Observer.handle,
-                observer,
+                &observer.event_node,
                 false,
             );
-            try parser.eventTargetAddZigListener(
+            try parser.eventTargetAddEventListener(
                 parser.toEventTarget(parser.Node, node),
-                arena,
                 "DOMNodeRemoved",
-                Observer.handle,
-                observer,
+                &observer.event_node,
                 false,
             );
         }
         if (options.attr()) {
-            try parser.eventTargetAddZigListener(
+            try parser.eventTargetAddEventListener(
                 parser.toEventTarget(parser.Node, node),
-                arena,
                 "DOMAttrModified",
-                Observer.handle,
-                observer,
+                &observer.event_node,
                 false,
             );
         }
         if (options.cdata()) {
-            try parser.eventTargetAddZigListener(
+            try parser.eventTargetAddEventListener(
                 parser.toEventTarget(parser.Node, node),
-                arena,
                 "DOMCharacterDataModified",
-                Observer.handle,
-                observer,
+                &observer.event_node,
                 false,
             );
         }
         if (options.subtree) {
-            try parser.eventTargetAddZigListener(
+            try parser.eventTargetAddEventListener(
                 parser.toEventTarget(parser.Node, node),
-                arena,
                 "DOMSubtreeModified",
-                Observer.handle,
-                observer,
+                &observer.event_node,
                 false,
             );
         }
@@ -221,6 +210,8 @@ const Observer = struct {
     // and batch the mutation records.
     mutation_observer: *MutationObserver,
 
+    event_node: parser.EventNode,
+
     fn appliesTo(o: *const Observer, target: *parser.Node) bool {
         // mutation on any target is always ok.
         if (o.options.subtree) {
@@ -250,9 +241,9 @@ const Observer = struct {
         return false;
     }
 
-    fn handle(ctx: *anyopaque, event: *parser.Event) void {
-        // retrieve the observer from the data.
-        var self: *Observer = @alignCast(@ptrCast(ctx));
+    fn handle(en: *parser.EventNode, event: *parser.Event) void {
+        const self: *Observer = @fieldParentPtr("event_node", en);
+
         var mutation_observer = self.mutation_observer;
 
         const node = blk: {

src/browser/events/event.zig

@@ -17,6 +17,7 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 const std = @import("std");
+const Allocator = std.mem.Allocator;
 
 const parser = @import("../netsurf.zig");
 const Callback = @import("../env.zig").Callback;
@@ -136,14 +137,35 @@ pub const Event = struct {
 };
 
 pub const EventHandler = struct {
-    fn handle(event: ?*parser.Event, data: *const parser.JSEventHandlerData) void {
+    callback: Callback,
+    node: parser.EventNode,
+
+    pub fn init(allocator: Allocator, callback: Callback) !*EventHandler {
+        const eh = try allocator.create(EventHandler);
+        eh.* = .{
+            .callback = callback,
+            .node = .{
+                .id = callback.id,
+                .func = handle,
+            },
+        };
+        return eh;
+    }
+
+    fn handle(node: *parser.EventNode, event: *parser.Event) void {
+        const ievent = Event.toInterface(event) catch |err| {
+            log.err("Event.toInterface: {}", .{err});
+            return;
+        };
+
+        const self: *EventHandler = @fieldParentPtr("node", node);
         var result: Callback.Result = undefined;
-        data.cbk.tryCall(.{if (event) |evt| Event.toInterface(evt) catch unreachable else null}, &result) catch {
+        self.callback.tryCall(.{ievent}, &result) catch {
             log.err("event handler error: {s}", .{result.exception});
             log.debug("stack:\n{s}", .{result.stack orelse "???"});
         };
     }
-}.handle;
+};
 
 const testing = @import("../../testing.zig");
 test "Browser.Event" {

src/browser/netsurf.zig

@@ -29,9 +29,6 @@ const c = @cImport({
 
 const mimalloc = @import("mimalloc.zig");
 
-const Callback = @import("env.zig").Callback;
-const SessionState = @import("env.zig").SessionState;
-
 // init initializes netsurf lib.
 // init starts a mimalloc heap arena for the netsurf session. The caller must
 // call deinit() to free the arena memory.
@@ -587,11 +584,61 @@ pub inline fn toEventTarget(comptime T: type, v: *T) *EventTarget {
     return @as(*EventTarget, @ptrCast(et_aligned));
 }
 
+// The way we implement events is a lot like how Zig implements linked lists.
+// A Zig struct contains an `EventNode` field, i.e.:
+//    node: parser.EventNode,
+//
+// When eventTargetAddEventListener is called, we pass in `&self.node`.
+// This is the pointer that's stored in the netsurf listener and it's the data
+// we can get back from the listener. We can call the node's `func` function,
+// passing the node itself, and the receiving function will know how to turn
+// that node into the our "self", i..e by using @fieldParentPtr.
+// https://www.openmymind.net/Zigs-New-LinkedList-API/
+pub const EventNode = struct {
+    // Event id, used for removing. Internal Zig events won't have an id.
+    // This is normally set to the callback.id for a JavaScript event.
+    id: ?usize = null,
+
+    func: *const fn (node: *EventNode, event: *Event) void,
+
+    fn idFromListener(lst: *EventListener) ?usize {
+        const ctx = eventListenerGetData(lst) orelse return null;
+        const node: *EventNode = @alignCast(@ptrCast(ctx));
+        return node.id;
+    }
+};
+
+pub fn eventTargetAddEventListener(
+    et: *EventTarget,
+    typ: []const u8,
+    node: *EventNode,
+    capture: bool,
+) !void {
+    const event_handler = struct {
+        fn handle(event_: ?*Event, ptr_: ?*anyopaque) callconv(.C) void {
+            const ptr = ptr_ orelse return;
+            const event = event_ orelse return;
+
+            const node_: *EventNode = @alignCast(@ptrCast(ptr));
+            node_.func(node_, event);
+        }
+    }.handle;
+
+    var listener: ?*EventListener = undefined;
+    const errLst = c.dom_event_listener_create(event_handler, node, &listener);
+    try DOMErr(errLst);
+    defer c.dom_event_listener_unref(listener);
+
+    const s = try strFromData(typ);
+    const err = eventTargetVtable(et).add_event_listener.?(et, s, listener, capture);
+    try DOMErr(err);
+}
+
 pub fn eventTargetHasListener(
     et: *EventTarget,
     typ: []const u8,
     capture: bool,
-    cbk_id: usize,
+    id: usize,
 ) !?*EventListener {
     const str = try strFromData(typ);
 
@@ -616,12 +663,9 @@ pub fn eventTargetHasListener(
             // and capture property,
             // let's check if the callback handler is the same
             defer c.dom_event_listener_unref(listener);
-            if (EventHandlerData.fromListener(listener)) |ehd| {
-                switch (ehd.*) {
-                    .js => |js| if (cbk_id == js.data.cbk.id) {
-                        return lst;
-                    },
-                    .zig => {},
+            if (EventNode.idFromListener(listener)) |node_id| {
+                if (node_id == id) {
+                    return lst;
                 }
             }
         }
@@ -638,144 +682,18 @@ pub fn eventTargetHasListener(
     return null;
 }
 
-// The *anyopque that get stored in the libdom listener, which we'll retrieve
-// when then event is dispatched so that we can execute the JS or Zig callback.
-const EventHandlerData = union(enum) {
-    js: JS,
-    zig: Zig,
-
-    const JS = struct {
-        data: JSEventHandlerData,
-        func: JSEventHandlerFunc,
-    };
-
-    const Zig = struct {
-        ctx: *anyopaque,
-        func: ZigEventHandlerFunc,
-    };
-
-    // retrieve a EventHandlerDataInternal from a listener.
-    fn fromListener(lst: *EventListener) ?*EventHandlerData {
-        const ctx = eventListenerGetData(lst) orelse return null;
-        const ehd: *EventHandlerData = @alignCast(@ptrCast(ctx));
-        return ehd;
-    }
-
-    pub fn deinit(self: *EventHandlerData, alloc: std.mem.Allocator) void {
-        switch (self.*) {
-            .js => |*js| {
-                const js_data = &js.data;
-                if (js_data.deinitFunc) |df| {
-                    df(js_data.ctx, alloc);
-                }
-            },
-            .zig => {},
-        }
-        alloc.destroy(self);
-    }
-
-    pub fn handle(self: *EventHandlerData, event: ?*Event) void {
-        switch (self.*) {
-            .js => |*js| js.func(event, &js.data),
-            .zig => |zig| zig.func(zig.ctx, event.?),
-        }
-    }
-};
-
-pub const JSEventHandlerData = struct {
-    cbk: Callback,
-    ctx: ?*anyopaque = null,
-    // deinitFunc implements the data deinitialization.
-    deinitFunc: ?DeinitFunc = null,
-
-    pub const DeinitFunc = *const fn (data: ?*anyopaque, alloc: std.mem.Allocator) void;
-};
-
-const JSEventHandlerFunc = *const fn (event: ?*Event, data: *JSEventHandlerData) void;
-const ZigEventHandlerFunc = *const fn (ctx: *anyopaque, event: *Event) void;
-
-pub fn eventTargetAddEventListener(
-    et: *EventTarget,
-    alloc: std.mem.Allocator,
-    typ: []const u8,
-    func: JSEventHandlerFunc,
-    data: JSEventHandlerData,
-    capture: bool,
-) !void {
-    // this allocation will be removed either on
-    // eventTargetRemoveEventListener or eventTargetRemoveAllEventListeners
-    const ehd = try alloc.create(EventHandlerData);
-    errdefer alloc.destroy(ehd);
-    ehd.* = .{ .js = .{ .data = data, .func = func } };
-    errdefer ehd.deinit(alloc);
-
-    // When a function is used as an event handler, its this parameter is bound
-    // to the DOM element on which the listener is placed.
-    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/this#this_in_dom_event_handlers
-    try ehd.js.data.cbk.setThis(et);
-
-    return addEventTargetListener(et, typ, ehd, capture);
-}
-
-pub fn eventTargetAddZigListener(
-    et: *EventTarget,
-    alloc: std.mem.Allocator,
-    typ: []const u8,
-    func: ZigEventHandlerFunc,
-    ctx: *anyopaque,
-    capture: bool,
-) !void {
-    const ehd = try alloc.create(EventHandlerData);
-    errdefer alloc.destroy(ehd);
-    ehd.* = .{ .zig = .{ .ctx = ctx, .func = func } };
-    return addEventTargetListener(et, typ, ehd, capture);
-}
-
-fn addEventTargetListener(et: *EventTarget, typ: []const u8, data: *anyopaque, capture: bool) !void {
-    // event_handler implements the function exposed in C and called by libdom.
-    // It retrieves the EventHandler and calls the appropriate (JS or Zig)
-    // handler function with the corresponding data.
-    const event_handler = struct {
-        fn handle(event: ?*Event, ptr_: ?*anyopaque) callconv(.C) void {
-            const ptr = ptr_ orelse return;
-            @as(*EventHandlerData, @alignCast(@ptrCast(ptr))).handle(event);
-            // NOTE: we can not call func.deinit here
-            // b/c the handler can be called several times
-            // either on this dispatch event or in anoter one
-        }
-    }.handle;
-
-    var listener: ?*EventListener = undefined;
-    const errLst = c.dom_event_listener_create(event_handler, data, &listener);
-    try DOMErr(errLst);
-    defer c.dom_event_listener_unref(listener);
-
-    const s = try strFromData(typ);
-    const err = eventTargetVtable(et).add_event_listener.?(et, s, listener, capture);
-    try DOMErr(err);
-}
-
 pub fn eventTargetRemoveEventListener(
     et: *EventTarget,
-    alloc: std.mem.Allocator,
     typ: []const u8,
     lst: *EventListener,
     capture: bool,
 ) !void {
-    // free data allocation made on eventTargetAddEventListener
-    if (EventHandlerData.fromListener(lst)) |ehd| {
-        ehd.deinit(alloc);
-    }
-
     const s = try strFromData(typ);
     const err = eventTargetVtable(et).remove_event_listener.?(et, s, lst, capture);
     try DOMErr(err);
 }
 
-pub fn eventTargetRemoveAllEventListeners(
-    et: *EventTarget,
-    alloc: std.mem.Allocator,
-) !void {
+pub fn eventTargetRemoveAllEventListeners(et: *EventTarget) !void {
     var next: ?*EventListenerEntry = undefined;
     var lst: ?*EventListener = undefined;
 
@@ -792,15 +710,8 @@ pub fn eventTargetRemoveAllEventListeners(
         try DOMErr(errIter);
 
         if (lst) |listener| {
-            defer c.dom_event_listener_unref(listener);
-
-            if (EventHandlerData.fromListener(listener)) |ehd| {
-                if (ehd.* == .zig) {
-                    // we don't remove Zig listeners
-                    continue;
-                }
-
-                ehd.deinit(alloc);
+            if (EventNode.idFromListener(listener) != null) {
+                defer c.dom_event_listener_unref(listener);
                 const err = eventTargetVtable(et).remove_event_listener.?(
                     et,
                     null,

src/browser/xhr/event_target.zig

@@ -48,25 +48,25 @@ pub const XMLHttpRequestEventTarget = struct {
         typ: []const u8,
         cbk: Callback,
     ) !void {
+        const target = @as(*parser.EventTarget, @ptrCast(self));
+        const eh = try EventHandler.init(alloc, try cbk.withThis(target));
         try parser.eventTargetAddEventListener(
-            @as(*parser.EventTarget, @ptrCast(self)),
-            alloc,
+            target,
             typ,
-            EventHandler,
-            .{ .cbk = cbk },
+            &eh.node,
             false,
         );
     }
-    fn unregister(self: *XMLHttpRequestEventTarget, alloc: std.mem.Allocator, typ: []const u8, cbk: Callback) !void {
+    fn unregister(self: *XMLHttpRequestEventTarget, typ: []const u8, cbk_id: usize) !void {
         const et = @as(*parser.EventTarget, @ptrCast(self));
         // check if event target has already this listener
-        const lst = try parser.eventTargetHasListener(et, typ, false, cbk.id);
+        const lst = try parser.eventTargetHasListener(et, typ, false, cbk_id);
         if (lst == null) {
             return;
         }
 
         // remove listener
-        try parser.eventTargetRemoveEventListener(et, alloc, typ, lst.?, false);
+        try parser.eventTargetRemoveEventListener(et, typ, lst.?, false);
     }
 
     pub fn get_onloadstart(self: *XMLHttpRequestEventTarget) ?Callback {
@@ -89,39 +89,33 @@ pub const XMLHttpRequestEventTarget = struct {
     }
 
     pub fn set_onloadstart(self: *XMLHttpRequestEventTarget, handler: Callback, state: *SessionState) !void {
-        const arena = state.arena;
-        if (self.onloadstart_cbk) |cbk| try self.unregister(arena, "loadstart", cbk);
-        try self.register(arena, "loadstart", handler);
+        if (self.onloadstart_cbk) |cbk| try self.unregister("loadstart", cbk.id);
+        try self.register(state.arena, "loadstart", handler);
         self.onloadstart_cbk = handler;
     }
     pub fn set_onprogress(self: *XMLHttpRequestEventTarget, handler: Callback, state: *SessionState) !void {
-        const arena = state.arena;
-        if (self.onprogress_cbk) |cbk| try self.unregister(arena, "progress", cbk);
-        try self.register(arena, "progress", handler);
+        if (self.onprogress_cbk) |cbk| try self.unregister("progress", cbk.id);
+        try self.register(state.arena, "progress", handler);
         self.onprogress_cbk = handler;
     }
     pub fn set_onabort(self: *XMLHttpRequestEventTarget, handler: Callback, state: *SessionState) !void {
-        const arena = state.arena;
-        if (self.onabort_cbk) |cbk| try self.unregister(arena, "abort", cbk);
-        try self.register(arena, "abort", handler);
+        if (self.onabort_cbk) |cbk| try self.unregister("abort", cbk.id);
+        try self.register(state.arena, "abort", handler);
         self.onabort_cbk = handler;
     }
     pub fn set_onload(self: *XMLHttpRequestEventTarget, handler: Callback, state: *SessionState) !void {
-        const arena = state.arena;
-        if (self.onload_cbk) |cbk| try self.unregister(arena, "load", cbk);
-        try self.register(arena, "load", handler);
+        if (self.onload_cbk) |cbk| try self.unregister("load", cbk.id);
+        try self.register(state.arena, "load", handler);
         self.onload_cbk = handler;
     }
     pub fn set_ontimeout(self: *XMLHttpRequestEventTarget, handler: Callback, state: *SessionState) !void {
-        const arena = state.arena;
-        if (self.ontimeout_cbk) |cbk| try self.unregister(arena, "timeout", cbk);
-        try self.register(arena, "timeout", handler);
+        if (self.ontimeout_cbk) |cbk| try self.unregister("timeout", cbk.id);
+        try self.register(state.arena, "timeout", handler);
         self.ontimeout_cbk = handler;
     }
     pub fn set_onloadend(self: *XMLHttpRequestEventTarget, handler: Callback, state: *SessionState) !void {
-        const arena = state.arena;
-        if (self.onloadend_cbk) |cbk| try self.unregister(arena, "loadend", cbk);
-        try self.register(arena, "loadend", handler);
+        if (self.onloadend_cbk) |cbk| try self.unregister("loadend", cbk.id);
+        try self.register(state.arena, "loadend", handler);
         self.onloadend_cbk = handler;
     }
 

src/runtime/js.zig

@@ -766,7 +766,7 @@ pub fn Env(comptime S: type, comptime types: anytype) type {
         pub const Callback = struct {
             id: usize,
             scope: *Scope,
-            _this: ?v8.Object = null,
+            this: ?v8.Object = null,
             func: PersistentFunction,
 
             // We use this when mapping a JS value to a Zig object. We can't
@@ -781,8 +781,13 @@ pub fn Env(comptime S: type, comptime types: anytype) type {
                 exception: []const u8,
             };
 
-            pub fn setThis(self: *Callback, value: anytype) !void {
-                self._this = try self.scope.valueToExistingObject(value);
+            pub fn withThis(self: *const Callback, value: anytype) !Callback {
+                return .{
+                    .id = self.id,
+                    .func = self.func,
+                    .scope = self.scope,
+                    .this = try self.scope.valueToExistingObject(value),
+                };
             }
 
             pub fn call(self: *const Callback, args: anytype) !void {
@@ -830,7 +835,7 @@ pub fn Env(comptime S: type, comptime types: anytype) type {
             }
 
             fn getThis(self: *const Callback) v8.Object {
-                return self._this orelse self.scope.context.getGlobal();
+                return self.this orelse self.scope.context.getGlobal();
             }
 
             // debug/helper to print the source of the JS callback