Add ability to get the parent item from the vtable

(still untested)

api/sixtyfps-cpp/include/sixtyfps.h

@@ -65,6 +65,7 @@ using cbindgen_private::ItemVTable;
 using ComponentRef = vtable::VRef<private_api::ComponentVTable>;
 using ItemRef = vtable::VRef<private_api::ItemVTable>;
 using ItemVisitorRefMut = vtable::VRefMut<cbindgen_private::ItemVisitorVTable>;
+using cbindgen_private::ItemWeak;
 }
 using cbindgen_private::ComponentRc;
 using cbindgen_private::EasingCurve;
@@ -165,16 +166,17 @@ using cbindgen_private::NativeStyleMetrics;
 namespace private_api {
 constexpr inline ItemTreeNode make_item_node(std::uintptr_t offset,
                                              const cbindgen_private::ItemVTable *vtable,
-                                             uint32_t child_count, uint32_t child_index)
+                                             uint32_t child_count, uint32_t child_index,
+                                             uint parent_index)
 {
     return ItemTreeNode { ItemTreeNode::Item_Body {
-            ItemTreeNode::Tag::Item, { vtable, offset }, child_count, child_index } };
+            ItemTreeNode::Tag::Item, { vtable, offset }, child_count, child_index, parent_index } };
 }
 
-constexpr inline ItemTreeNode make_dyn_node(std::uintptr_t offset)
+constexpr inline ItemTreeNode make_dyn_node(std::uintptr_t offset, std::uint32_t parent_index)
 {
-    return ItemTreeNode { ItemTreeNode::DynamicTree_Body { ItemTreeNode::Tag::DynamicTree,
-                                                           offset } };
+    return ItemTreeNode { ItemTreeNode::DynamicTree_Body {
+        ItemTreeNode::Tag::DynamicTree, offset, parent_index } };
 }
 
 inline ItemRef get_item_ref(ComponentRef component, Slice<ItemTreeNode> item_tree, int index)
@@ -183,6 +185,17 @@ inline ItemRef get_item_ref(ComponentRef component, Slice<ItemTreeNode> item_tre
     return ItemRef { item.vtable, reinterpret_cast<char *>(component.instance) + item.offset };
 }
 
+inline ItemWeak parent_item(cbindgen_private::ComponentWeak component,
+                                Slice<ItemTreeNode> item_tree, int index)
+{
+    const auto &node = item_tree.ptr[index];
+    if (node.tag == ItemTreeNode::Tag::Item) {
+        return { component, node.item.parent_index };
+    } else {
+        return { component, node.dynamic_tree.parent_index };
+    }
+}
+
 }
 
 using cbindgen_private::FocusEvent;

api/sixtyfps-cpp/include/vtable.h

@@ -167,6 +167,8 @@ public:
         inner->strong_ref++;
         return { VRc<VTable, X>(inner) };
     }
+
+    VWeak<VTable, Dyn> into_dyn() const { return *reinterpret_cast<const VWeak<VTable, Dyn> *>(this); }
 };
 
 

sixtyfps_compiler/generator.rs

@@ -88,14 +88,18 @@ pub fn generate(
 }
 
 /// Visit each item in order in which they should appear in the children tree array.
-/// The parameter of the visitor are the item, and the first_children_offset, and wether this is the flickable rectangle
+/// The parameter of the visitor are
+///  1. the item
+///  2. the first_children_offset,
+///  3. the parent index
+///  4. wether this is the flickable rectangle
 #[allow(dead_code)]
 pub fn build_array_helper(
     component: &Component,
-    mut visit_item: impl FnMut(&ElementRc, u32, bool),
+    mut visit_item: impl FnMut(&ElementRc, u32, u32, bool),
 ) {
-    visit_item(&component.root_element, 1, false);
-    visit_children(&component.root_element, 1, &mut visit_item);
+    visit_item(&component.root_element, 1, 0, false);
+    visit_children(&component.root_element, &mut 0, 1, &mut visit_item);
 
     fn sub_children_count(e: &ElementRc) -> usize {
         let mut count = e.borrow().children.len();
@@ -110,29 +114,33 @@ pub fn build_array_helper(
 
     fn visit_children(
         item: &ElementRc,
+        index: &mut u32,
         children_offset: u32,
-        visit_item: &mut impl FnMut(&ElementRc, u32, bool),
+        visit_item: &mut impl FnMut(&ElementRc, u32, u32, bool),
     ) {
         let mut offset = children_offset + item.borrow().children.len() as u32;
 
         if is_flickable(item) {
-            visit_item(item, offset, true);
+            visit_item(item, offset, *index, true);
             offset += 1;
         }
 
         for i in &item.borrow().children {
-            visit_item(i, offset, false);
+            visit_item(i, offset, *index, false);
             offset += sub_children_count(i) as u32;
         }
 
+        *index += 1;
+
         let mut offset = children_offset + item.borrow().children.len() as u32;
 
         if is_flickable(item) {
             offset += 1;
+            *index += 1;
         }
 
         for e in &item.borrow().children {
-            visit_children(e, offset, visit_item);
+            visit_children(e, index, offset, visit_item);
             offset += sub_children_count(e) as u32;
         }
     }

sixtyfps_compiler/generator/cpp.rs

@@ -1003,15 +1003,18 @@ fn generate_component(
     let mut tree_array = vec![];
     let mut item_names_and_vt_symbols = vec![];
     let mut repeater_count = 0;
-    super::build_array_helper(component, |item_rc, children_offset, is_flickable_rect| {
+    super::build_array_helper(
+        component,
+        |item_rc, children_offset, parent_index, is_flickable_rect| {
             let item = item_rc.borrow();
             if is_flickable_rect {
                 tree_array.push(format!(
-                "sixtyfps::private_api::make_item_node(offsetof({}, {}) + offsetof(sixtyfps::Flickable, viewport), &sixtyfps::private_api::RectangleVTable, {}, {})",
+                "sixtyfps::private_api::make_item_node(offsetof({}, {}) + offsetof(sixtyfps::Flickable, viewport), &sixtyfps::private_api::RectangleVTable, {}, {}, {})",
                 &component_id,
                 item.id,
                 item.children.len(),
                 tree_array.len() + 1,
+                parent_index,
             ));
             } else if item.base_type == Type::Void {
                 assert!(component.is_global());
@@ -1019,7 +1022,10 @@ fn generate_component(
                     handle_property_binding(item_rc, prop_name, binding_expression, &mut init);
                 }
             } else if let Some(repeated) = &item.repeated {
-            tree_array.push(format!("sixtyfps::private_api::make_dyn_node({})", repeater_count,));
+                tree_array.push(format!(
+                    "sixtyfps::private_api::make_dyn_node({}, {})",
+                    repeater_count, parent_index
+                ));
                 let base_component = item.base_type.as_component();
                 let mut friends = Vec::new();
                 generate_component(file, base_component, diag, Some(&mut friends));
@@ -1044,18 +1050,20 @@ fn generate_component(
                 repeater_count += 1;
             } else {
                 tree_array.push(format!(
-                "sixtyfps::private_api::make_item_node(offsetof({}, {}), &sixtyfps::private_api::{}, {}, {})",
+                    "sixtyfps::private_api::make_item_node(offsetof({}, {}), &sixtyfps::private_api::{}, {}, {}, {})",
                     component_id,
                     item.id,
                     item.base_type.as_native().vtable_symbol,
                     if super::is_flickable(item_rc) { 1 } else { item.children.len() },
                     children_offset,
+                    parent_index,
                 ));
                 handle_item(item_rc, &mut component_struct, &mut init);
                 item_names_and_vt_symbols
                     .push((item.id.clone(), item.base_type.as_native().vtable_symbol.clone()));
             }
-    });
+        },
+    );
 
     if !component.is_global() {
         component_struct
@@ -1139,6 +1147,31 @@ fn generate_component(
             }),
         ));
 
+        let parent_item_from_parent_component = if let Some(parent_index) =
+            component.parent_element.upgrade().and_then(|e| e.borrow().item_index.get().map(|x| *x))
+        {
+            format!("   return {{ self->parent->self_weak.into_dyn(), {} }};", parent_index)
+        } else {
+            "    return {};".to_owned()
+        };
+
+        component_struct.members.push((
+            Access::Private,
+            Declaration::Function(Function {
+                name: "parent_item".into(),
+                signature: "(sixtyfps::private_api::ComponentRef component, uintptr_t index) -> sixtyfps::private_api::ItemWeak".into(),
+                is_static: true,
+                statements: Some(vec![
+                    format!("auto self = reinterpret_cast<const {}*>(component.instance);", component_id),
+                    "if (index == 0) {".into(),
+                    parent_item_from_parent_component,
+                    "}".into(),
+                    "return sixtyfps::private_api::parent_item(self->self_weak.into_dyn(), item_tree(), index);".into(),
+                ]),
+                ..Default::default()
+            }),
+        ));
+
         component_struct.members.push((
             Access::Private,
             Declaration::Function(Function {
@@ -1232,7 +1265,7 @@ fn generate_component(
             ty: "const sixtyfps::private_api::ComponentVTable".to_owned(),
             name: format!("{}::static_vtable", component_id),
             init: Some(format!(
-                "{{ visit_children, get_item_ref, layouting_info, apply_layout,  sixtyfps::private_api::drop_in_place<{}>, sixtyfps::private_api::dealloc }}",
+                "{{ visit_children, get_item_ref, parent_item,  layouting_info, apply_layout,  sixtyfps::private_api::drop_in_place<{}>, sixtyfps::private_api::dealloc }}",
                 component_id)
             ),
         }));

sixtyfps_compiler/generator/rust.rs

@@ -373,7 +373,10 @@ fn generate_component(
     let mut init = Vec::new();
     let mut window_field_init = None;
     let mut window_parent_param = None;
-    super::build_array_helper(component, |item_rc, children_index, is_flickable_rect| {
+    super::build_array_helper(
+        component,
+        |item_rc, children_index, parent_index, is_flickable_rect| {
+            let parent_index = parent_index as u32;
             let item = item_rc.borrow();
             if is_flickable_rect {
                 let field_name = format_ident!("{}", item.id);
@@ -385,6 +388,7 @@ fn generate_component(
                     item: VOffset::new(#inner_component_id::FIELD_OFFSETS.#field_name + sixtyfps::re_exports::Flickable::FIELD_OFFSETS.viewport),
                     chilren_count: #children_count,
                     children_index: #children_index,
+                    parent_index: #parent_index
                 }
             ));
             } else if item.base_type == Type::Void {
@@ -474,8 +478,7 @@ fn generate_component(
 
                 let mut model = compile_expression(&repeated.model, component);
                 if repeated.is_conditional_element {
-                model =
-                    quote!(sixtyfps::re_exports::ModelHandle::new(std::rc::Rc::<bool>::new(#model)))
+                    model = quote!(sixtyfps::re_exports::ModelHandle::new(std::rc::Rc::<bool>::new(#model)))
                 }
 
                 // FIXME: there could be an optimization if `repeated.model.is_constant()`, we don't need a binding
@@ -491,7 +494,8 @@ fn generate_component(
                 });
 
                 if let Some(listview) = &repeated.is_listview {
-                let vp_y = access_named_reference(&listview.viewport_y, component, quote!(_self));
+                    let vp_y =
+                        access_named_reference(&listview.viewport_y, component, quote!(_self));
                     let vp_h =
                         access_named_reference(&listview.viewport_height, component, quote!(_self));
                     let lv_h =
@@ -540,6 +544,7 @@ fn generate_component(
                 item_tree_array.push(quote!(
                     sixtyfps::re_exports::ItemTreeNode::DynamicTree {
                         index: #repeater_index,
+                        parent_index: #parent_index,
                     }
                 ));
 
@@ -555,6 +560,7 @@ fn generate_component(
                         item: VOffset::new(#inner_component_id::FIELD_OFFSETS.#field_name),
                         chilren_count: #children_count,
                         children_index: #children_index,
+                        parent_index: #parent_index,
                     }
                 ));
                 for (k, binding_expression) in &item.bindings {
@@ -563,7 +569,8 @@ fn generate_component(
                 item_names.push(field_name);
                 item_types.push(format_ident!("{}", item.base_type.as_native().class_name));
             }
-    });
+        },
+    );
 
     let resource_symbols: Vec<proc_macro2::TokenStream> = component
         .embedded_file_resources
@@ -661,6 +668,11 @@ fn generate_component(
         (None, None)
     } else {
         let item_tree_array_len = item_tree_array.len();
+        let parent_item_index = component
+            .parent_element
+            .upgrade()
+            .and_then(|e| e.borrow().item_index.get().map(|x| *x));
+        let parent_item_index = parent_item_index.iter();
         init.insert(0, quote!(sixtyfps::re_exports::init_component_items(_self, Self::item_tree(), &_self.window);));
         (
             Some(quote! {
@@ -700,6 +712,23 @@ fn generate_component(
 
                     }
                 }
+
+                fn parent_item(self: ::core::pin::Pin<&Self>, index: usize) -> sixtyfps::re_exports::ItemWeak {
+                    if index == 0 {
+                        #(
+                            if let Some(parent) = self.parent.clone().into_dyn().upgrade() {
+                                return sixtyfps::re_exports::ItemRc::new(parent, #parent_item_index).downgrade();
+                            }
+                        )*
+                        return sixtyfps::re_exports::ItemWeak::default();
+                    }
+                    let parent_index = match &Self::item_tree()[index] {
+                        ItemTreeNode::Item { parent_index, .. } => *parent_index,
+                        ItemTreeNode::DynamicTree { parent_index, .. } => *parent_index,
+                    };
+                    let self_rc = self.self_weak.get().unwrap().clone().into_dyn().upgrade().unwrap();
+                    ItemRc::new(self_rc, parent_index as _).downgrade()
+                }
             }
             }),
         )

sixtyfps_compiler/lib.rs

@@ -190,19 +190,22 @@ pub async fn run_passes(
 
     fn generate_item_indices(component: &Rc<object_tree::Component>) {
         let mut current_item_index: usize = 0;
-        generator::build_array_helper(&component, move |item_rc, _, is_flickable_rect| {
+        generator::build_array_helper(&component, move |item_rc, _, _, is_flickable_rect| {
             let item = item_rc.borrow();
             if is_flickable_rect {
                 current_item_index += 1;
             } else if item.base_type == crate::langtype::Type::Void {
-            } else if item.repeated.is_some() {
-                generate_item_indices(&*item.base_type.as_component());
-                current_item_index += 1;
             } else {
+                if let langtype::Type::Component(c) = &item.base_type {
+                    generate_item_indices(c);
+                }
                 item.item_index.set(current_item_index).unwrap();
                 current_item_index += 1;
             }
         });
+        for p in component.popup_windows.borrow().iter() {
+            generate_item_indices(&p.component)
+        }
     }
 
     generate_item_indices(&doc.root_component);

sixtyfps_runtime/corelib/component.rs

@@ -13,7 +13,7 @@ LICENSE END */
 
 use crate::graphics::Rect;
 use crate::item_tree::{ItemVisitorVTable, TraversalOrder, VisitChildrenResult};
-use crate::items::ItemVTable;
+use crate::items::{ItemVTable, ItemWeak};
 use crate::layout::LayoutInfo;
 use crate::window::ComponentWindow;
 use vtable::*;
@@ -38,6 +38,10 @@ pub struct ComponentVTable {
         index: usize,
     ) -> core::pin::Pin<VRef<ItemVTable>>,
 
+    /// Return the parent item. The return value is an item weak because it can be null if
+    /// there is no parent
+    pub parent_item: extern "C" fn(core::pin::Pin<VRef<ComponentVTable>>, index: usize) -> ItemWeak,
+
     /// Returns the layout info for this component
     pub layout_info: extern "C" fn(core::pin::Pin<VRef<ComponentVTable>>) -> LayoutInfo,
 

sixtyfps_runtime/corelib/item_tree.rs

@@ -84,12 +84,18 @@ pub enum ItemTreeNode<T> {
 
         /// index of the first children within the item tree
         children_index: u32,
+
+        /// The index of the parent item (not valid for the root)
+        parent_index: u32,
     },
     /// A placeholder for many instance of item in their own component which
     /// are instantiated according to a model.
     DynamicTree {
         /// the undex which is passed in the visit_dynamic callback.
         index: usize,
+
+        /// The index of the parent item (not valid for the root)
+        parent_index: u32,
     },
 }
 
@@ -230,7 +236,7 @@ pub fn visit_item_tree<Base>(
             ItemTreeNode::Item { item, .. } => {
                 visitor.visit_item(component, idx, item.apply_pin(base))
             }
-            ItemTreeNode::DynamicTree { index } => {
+            ItemTreeNode::DynamicTree { index, .. } => {
                 if let Some(sub_idx) =
                     visit_dynamic(base, order, visitor.borrow_mut(), *index).aborted_index()
                 {

sixtyfps_runtime/corelib/items.rs

@@ -132,6 +132,7 @@ impl ItemRc {
 
 /// A Weak reference to an item that can be constructed from an ItemRc.
 #[derive(Default, Clone)]
+#[repr(C)]
 pub struct ItemWeak {
     component: crate::component::ComponentWeak,
     index: usize,

sixtyfps_runtime/interpreter/dynamic_component.rs

@@ -23,7 +23,9 @@ use sixtyfps_corelib::graphics::{Rect, Resource};
 use sixtyfps_corelib::item_tree::{
     ItemTreeNode, ItemVisitorRefMut, ItemVisitorVTable, TraversalOrder, VisitChildrenResult,
 };
-use sixtyfps_corelib::items::{Flickable, ItemRef, ItemVTable, PropertyAnimation, Rectangle};
+use sixtyfps_corelib::items::{
+    Flickable, ItemRc, ItemRef, ItemVTable, ItemWeak, PropertyAnimation, Rectangle,
+};
 use sixtyfps_corelib::layout::{LayoutInfo, Padding};
 use sixtyfps_corelib::model::RepeatedComponent;
 use sixtyfps_corelib::model::Repeater;
@@ -209,6 +211,9 @@ impl Component for ErasedComponentBox {
         // indirection and call our implementation directly.
         unsafe { get_item_ref(self.get_ref().borrow(), index) }
     }
+    fn parent_item(self: Pin<&Self>, index: usize) -> ItemWeak {
+        self.borrow().as_ref().parent_item(index)
+    }
 }
 
 sixtyfps_corelib::ComponentVTable_static!(static COMPONENT_BOX_VT for ErasedComponentBox);
@@ -517,19 +522,22 @@ fn generate_component<'id>(
     let mut repeater = vec![];
     let mut repeater_names = HashMap::new();
 
-    generator::build_array_helper(component, |rc_item, child_offset, is_flickable_rect| {
+    generator::build_array_helper(
+        component,
+        |rc_item, child_offset, parent_index, is_flickable_rect| {
             let item = rc_item.borrow();
             if is_flickable_rect {
                 use vtable::HasStaticVTable;
-            let offset =
-                items_types[&item.id].offset + Flickable::FIELD_OFFSETS.viewport.get_byte_offset();
+                let offset = items_types[&item.id].offset
+                    + Flickable::FIELD_OFFSETS.viewport.get_byte_offset();
                 tree_array.push(ItemTreeNode::Item {
                     item: unsafe { vtable::VOffset::from_raw(Rectangle::static_vtable(), offset) },
                     children_index: tree_array.len() as u32 + 1,
                     chilren_count: item.children.len() as _,
+                    parent_index,
                 });
             } else if let Some(repeated) = &item.repeated {
-            tree_array.push(ItemTreeNode::DynamicTree { index: repeater.len() });
+                tree_array.push(ItemTreeNode::DynamicTree { index: repeater.len(), parent_index });
                 let base_component = item.base_type.as_component();
                 repeater_names.insert(item.id.clone(), repeater.len());
                 generativity::make_guard!(guard);
@@ -554,13 +562,15 @@ fn generate_component<'id>(
                     } else {
                         item.children.len() as _
                     },
+                    parent_index,
                 });
                 items_types.insert(
                     item.id.clone(),
                     ItemWithinComponent { offset, rtti: rt.clone(), elem: rc_item.clone() },
                 );
             }
-    });
+        },
+    );
 
     let mut custom_properties = HashMap::new();
     let mut custom_callbacks = HashMap::new();
@@ -672,6 +682,7 @@ fn generate_component<'id>(
         layout_info,
         apply_layout,
         get_item_ref,
+        parent_item,
         drop_in_place,
         dealloc,
     };
@@ -1479,6 +1490,43 @@ unsafe extern "C" fn get_item_ref(component: ComponentRefPin, index: usize) -> P
     }
 }
 
+unsafe extern "C" fn parent_item(component: ComponentRefPin, index: usize) -> ItemWeak {
+    generativity::make_guard!(guard);
+    let instance_ref = InstanceRef::from_pin_ref(component, guard);
+    if index == 0 {
+        let parent_item_index = instance_ref
+            .component_type
+            .original
+            .parent_element
+            .upgrade()
+            .and_then(|e| e.borrow().item_index.get().map(|x| *x));
+        if let (Some(parent_offset), Some(parent_index)) =
+            (instance_ref.component_type.parent_component_offset, parent_item_index)
+        {
+            if let Some(parent) = parent_offset.apply(instance_ref.as_ref()) {
+                generativity::make_guard!(new_guard);
+                let parent_instance = InstanceRef::from_pin_ref(*parent, new_guard);
+                let parent_rc = parent_instance
+                    .self_weak()
+                    .get()
+                    .unwrap()
+                    .clone()
+                    .into_dyn()
+                    .upgrade()
+                    .unwrap();
+                return ItemRc::new(parent_rc, parent_index).downgrade();
+            };
+        }
+        return ItemWeak::default();
+    }
+    let parent_index = match &instance_ref.component_type.item_tree.as_slice()[index] {
+        ItemTreeNode::Item { parent_index, .. } => parent_index,
+        ItemTreeNode::DynamicTree { parent_index, .. } => parent_index,
+    };
+    let self_rc = instance_ref.self_weak().get().unwrap().clone().into_dyn().upgrade().unwrap();
+    ItemRc::new(self_rc, *parent_index as _).downgrade()
+}
+
 unsafe extern "C" fn drop_in_place(component: vtable::VRefMut<ComponentVTable>) -> vtable::Layout {
     let instance_ptr = component.as_ptr() as *mut Instance<'static>;
     let layout = (*instance_ptr).type_info().layout();