slint/sixtyfps_compiler/generator/cpp.rs

/* LICENSE BEGIN
    This file is part of the SixtyFPS Project -- https://sixtyfps.io
    Copyright (c) 2021 Olivier Goffart <olivier.goffart@sixtyfps.io>
    Copyright (c) 2021 Simon Hausmann <simon.hausmann@sixtyfps.io>

    SPDX-License-Identifier: GPL-3.0-only
    This file is also available under commercial licensing terms.
    Please contact info@sixtyfps.io for more information.
LICENSE END */
/*! module for the C++ code generator
*/

// cSpell:ignore cstdlib cmath constexpr nullptr decltype intptr uintptr

/// This module contains some data structure that helps represent a C++ code.
/// It is then rendered into an actual C++ text using the Display trait
mod cpp_ast {

    use std::cell::Cell;
    use std::fmt::{Display, Error, Formatter};
    thread_local!(static INDENTATION : Cell<u32> = Cell::new(0));
    fn indent(f: &mut Formatter<'_>) -> Result<(), Error> {
        INDENTATION.with(|i| {
            for _ in 0..(i.get()) {
                write!(f, "    ")?;
            }
            Ok(())
        })
    }

    ///A full C++ file
    #[derive(Default, Debug)]
    pub struct File {
        pub includes: Vec<String>,
        pub declarations: Vec<Declaration>,
        pub definitions: Vec<Declaration>,
    }

    impl Display for File {
        fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
            for i in &self.includes {
                writeln!(f, "#include {}", i)?;
            }
            for d in &self.declarations {
                write!(f, "\n{}", d)?;
            }
            for d in &self.definitions {
                write!(f, "\n{}", d)?;
            }
            Ok(())
        }
    }

    /// Declarations  (top level, or within a struct)
    #[derive(Debug, derive_more::Display)]
    pub enum Declaration {
        Struct(Struct),
        Function(Function),
        Var(Var),
        TypeAlias(TypeAlias),
    }

    #[derive(Debug, Copy, Clone, Eq, PartialEq)]
    pub enum Access {
        Public,
        Private,
        /*Protected,*/
    }

    #[derive(Default, Debug)]
    pub struct Struct {
        pub name: String,
        pub members: Vec<(Access, Declaration)>,
        pub friends: Vec<String>,
    }

    impl Display for Struct {
        fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
            indent(f)?;
            if self.members.is_empty() && self.friends.is_empty() {
                writeln!(f, "class {};", self.name)
            } else {
                writeln!(f, "class {} {{", self.name)?;
                INDENTATION.with(|x| x.set(x.get() + 1));
                let mut access = Access::Private;
                for m in &self.members {
                    if m.0 != access {
                        access = m.0;
                        indent(f)?;
                        match access {
                            Access::Public => writeln!(f, "public:")?,
                            Access::Private => writeln!(f, "private:")?,
                        }
                    }
                    write!(f, "{}", m.1)?;
                }
                for friend in &self.friends {
                    indent(f)?;
                    writeln!(f, "friend class {};", friend)?;
                }
                INDENTATION.with(|x| x.set(x.get() - 1));
                indent(f)?;
                writeln!(f, "}};")
            }
        }
    }

    impl Struct {
        pub fn extract_definitions(&mut self) -> impl Iterator<Item = Declaration> + '_ {
            let struct_name = self.name.clone();
            self.members.iter_mut().filter_map(move |x| match &mut x.1 {
                Declaration::Function(f) if f.statements.is_some() => {
                    Some(Declaration::Function(Function {
                        name: format!("{}::{}", struct_name, f.name),
                        signature: f.signature.clone(),
                        is_constructor_or_destructor: f.is_constructor_or_destructor,
                        is_static: false,
                        is_friend: false,
                        statements: f.statements.take(),
                        template_parameters: f.template_parameters.clone(),
                        constructor_member_initializers: f.constructor_member_initializers.clone(),
                    }))
                }
                _ => None,
            })
        }
    }

    /// Function or method
    #[derive(Default, Debug)]
    pub struct Function {
        pub name: String,
        /// "(...) -> ..."
        pub signature: String,
        /// The function does not have return type
        pub is_constructor_or_destructor: bool,
        pub is_static: bool,
        pub is_friend: bool,
        /// The list of statement instead the function.  When None,  this is just a function
        /// declaration without the definition
        pub statements: Option<Vec<String>>,
        /// What's inside template<...> if any
        pub template_parameters: Option<String>,
        /// Explicit initializers, such as FooClass::FooClass() : someMember(42) {}
        pub constructor_member_initializers: Vec<String>,
    }

    impl Display for Function {
        fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
            indent(f)?;
            if let Some(tpl) = &self.template_parameters {
                write!(f, "template<{}> ", tpl)?;
            }
            if self.is_static {
                write!(f, "static ")?;
            }
            if self.is_friend {
                write!(f, "friend ")?;
            }
            // all functions are `inline` because we are in a header
            write!(f, "inline ")?;
            if !self.is_constructor_or_destructor {
                write!(f, "auto ")?;
            }
            write!(f, "{} {}", self.name, self.signature)?;
            if let Some(st) = &self.statements {
                if !self.constructor_member_initializers.is_empty() {
                    writeln!(f, "\n : {}", self.constructor_member_initializers.join(","))?;
                }
                writeln!(f, "{{")?;
                for s in st {
                    indent(f)?;
                    writeln!(f, "    {}", s)?;
                }
                indent(f)?;
                writeln!(f, "}}")
            } else {
                writeln!(f, ";")
            }
        }
    }

    /// A variable or a member declaration.
    #[derive(Default, Debug)]
    pub struct Var {
        pub ty: String,
        pub name: String,
        pub array_size: Option<usize>,
        pub init: Option<String>,
    }

    impl Display for Var {
        fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
            indent(f)?;
            write!(f, "{} {}", self.ty, self.name)?;
            if let Some(size) = self.array_size {
                write!(f, "[{}]", size)?;
            }
            if let Some(i) = &self.init {
                write!(f, " = {}", i)?;
            }
            writeln!(f, ";")
        }
    }

    #[derive(Default, Debug)]
    pub struct TypeAlias {
        pub new_name: String,
        pub old_name: String,
    }

    impl Display for TypeAlias {
        fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
            indent(f)?;
            writeln!(f, "using {} = {};", self.new_name, self.old_name)
        }
    }

    pub trait CppType {
        fn cpp_type(&self) -> Option<String>;
    }

    pub fn escape_string(str: &str) -> String {
        let mut result = String::with_capacity(str.len());
        for x in str.chars() {
            match x {
                '\n' => result.push_str("\\n"),
                '\\' => result.push_str("\\\\"),
                '\"' => result.push_str("\\\""),
                '\t' => result.push_str("\\t"),
                '\r' => result.push_str("\\r"),
                _ if !x.is_ascii() || (x as u32) < 32 => {
                    use std::fmt::Write;
                    write!(result, "\\U{:0>8x}", x as u32).unwrap();
                }
                _ => result.push(x),
            }
        }
        result
    }
}

use crate::diagnostics::{BuildDiagnostics, Spanned};
use crate::expression_tree::{
    BindingExpression, BuiltinFunction, EasingCurve, Expression, NamedReference,
};
use crate::langtype::Type;
use crate::layout::{Layout, LayoutGeometry, LayoutRect, Orientation};
use crate::object_tree::{
    Component, Document, ElementRc, PropertyDeclaration, RepeatedElementInfo,
};
use cpp_ast::*;
use itertools::Itertools;
use std::borrow::Cow;
use std::collections::BTreeMap;
use std::rc::Rc;

fn ident(ident: &str) -> Cow<'_, str> {
    if ident.contains('-') {
        ident.replace('-', "_").into()
    } else {
        ident.into()
    }
}

impl CppType for Type {
    fn cpp_type(&self) -> Option<String> {
        match self {
            Type::Void => Some("void".to_owned()),
            Type::Float32 => Some("float".to_owned()),
            Type::Int32 => Some("int".to_owned()),
            Type::String => Some("sixtyfps::SharedString".to_owned()),
            Type::Color => Some("sixtyfps::Color".to_owned()),
            Type::Duration => Some("std::int64_t".to_owned()),
            Type::Angle => Some("float".to_owned()),
            Type::PhysicalLength => Some("float".to_owned()),
            Type::LogicalLength => Some("float".to_owned()),
            Type::Percent => Some("float".to_owned()),
            Type::Bool => Some("bool".to_owned()),
            Type::Struct { name: Some(name), node: Some(_), .. } => Some(ident(name).into_owned()),
            Type::Struct { name: Some(name), node: None, .. } => {
                Some(format!("sixtyfps::cbindgen_private::{}", ident(name)))
            }
            Type::Struct { fields, .. } => {
                let elem = fields.values().map(|v| v.cpp_type()).collect::<Option<Vec<_>>>()?;

                Some(format!("std::tuple<{}>", elem.join(", ")))
            }

            Type::Array(i) => Some(format!("std::shared_ptr<sixtyfps::Model<{}>>", i.cpp_type()?)),
            Type::Image => Some("sixtyfps::Image".to_owned()),
            Type::Builtin(elem) => elem.native_class.cpp_type.clone(),
            Type::Enumeration(enumeration) => {
                Some(format!("sixtyfps::cbindgen_private::{}", ident(&enumeration.name)))
            }
            Type::Brush => Some("sixtyfps::Brush".to_owned()),
            Type::LayoutCache => Some("sixtyfps::SharedVector<float>".into()),
            _ => None,
        }
    }
}

fn get_cpp_type(ty: &Type, decl: &PropertyDeclaration, diag: &mut BuildDiagnostics) -> String {
    ty.cpp_type().unwrap_or_else(|| {
        diag.push_error("Cannot map property type to C++".into(), &decl.type_node());
        "".into()
    })
}

fn to_cpp_orientation(o: Orientation) -> &'static str {
    match o {
        Orientation::Horizontal => "sixtyfps::Orientation::Horizontal",
        Orientation::Vertical => "sixtyfps::Orientation::Vertical",
    }
}

/// If the expression is surrounded with parentheses, remove these parentheses
fn remove_parentheses(expr: &str) -> &str {
    if expr.starts_with('(') && expr.ends_with(')') {
        &expr[1..expr.len() - 1]
    } else {
        expr
    }
}

fn new_struct_with_bindings(
    type_name: &str,
    bindings: &BTreeMap<String, BindingExpression>,
    component: &Rc<Component>,
) -> String {
    let bindings_initialization: Vec<String> = bindings
        .iter()
        .map(|(prop, initializer)| {
            let initializer = compile_expression(initializer, component);
            format!("var.{} = {};", ident(prop), initializer)
        })
        .collect();

    format!(
        r#"[&](){{
            {} var{{}};
            {}
            return var;
        }}()"#,
        type_name,
        bindings_initialization.join("\n")
    )
}

fn property_animation_code(component: &Rc<Component>, animation: &ElementRc) -> String {
    new_struct_with_bindings(
        "sixtyfps::cbindgen_private::PropertyAnimation",
        &animation.borrow().bindings,
        component,
    )
}

fn property_set_value_code(
    component: &Rc<Component>,
    element: &ElementRc,
    property_name: &str,
    value_expr: &str,
) -> String {
    match element.borrow().bindings.get(property_name).and_then(|b| b.animation.as_ref()) {
        Some(crate::object_tree::PropertyAnimation::Static(animation)) => {
            let animation_code = property_animation_code(component, animation);
            format!(
                "set_animated_value({value}, {animation})",
                value = value_expr,
                animation = animation_code
            )
        }
        _ => format!("set({})", value_expr),
    }
}

fn handle_property_binding(
    elem: &ElementRc,
    prop_name: &str,
    binding_expression: &BindingExpression,
    init: &mut Vec<String>,
) {
    let item = elem.borrow();
    let component = item.enclosing_component.upgrade().unwrap();
    let prop_access = access_member(elem, prop_name, &component, "this");
    let prop_type = item.lookup_property(prop_name).property_type;
    if let Type::Callback { args, .. } = &prop_type {
        if matches!(binding_expression.expression, Expression::Invalid) {
            return;
        }
        let mut params = args.iter().enumerate().map(|(i, ty)| {
            format!("[[maybe_unused]] {} arg_{}", ty.cpp_type().unwrap_or_default(), i)
        });

        init.push(format!(
            "{prop_access}.set_handler(
                    [this]({params}) {{
                        [[maybe_unused]] auto self = this;
                        return {code};
                    }});",
            prop_access = prop_access,
            params = params.join(", "),
            code = compile_expression_wrap_return(binding_expression, &component)
        ));
    } else {
        for nr in &binding_expression.two_way_bindings {
            init.push(format!(
                "sixtyfps::private_api::Property<{ty}>::link_two_way(&{p1}, &{p2});",
                ty = prop_type.cpp_type().unwrap_or_default(),
                p1 = prop_access,
                p2 = access_named_reference(nr, &component, "this")
            ));
        }
        if matches!(binding_expression.expression, Expression::Invalid) {
            return;
        }

        let component = &item.enclosing_component.upgrade().unwrap();

        let init_expr = compile_expression_wrap_return(binding_expression, component);

        let is_constant =
            binding_expression.analysis.borrow().as_ref().map_or(false, |a| a.is_const);
        init.push(if is_constant {
            format!("{}.set({});", prop_access, init_expr)
        } else {
            let binding_code = format!(
                "[this]() {{
                            [[maybe_unused]] auto self = this;
                            return {init};
                        }}",
                init = init_expr
            );

            let is_state_info = matches!(prop_type, Type::Struct { name: Some(name), .. } if name.ends_with("::StateInfo"));
            if is_state_info {
                format!("sixtyfps::private_api::set_state_binding({}, {});", prop_access, binding_code)
            } else {
                match &binding_expression.animation {
                    Some(crate::object_tree::PropertyAnimation::Static(anim)) => {
                        let anim = property_animation_code(component, anim);
                        format!("{}.set_animated_binding({}, {});", prop_access, binding_code, anim)
                    }
                    Some(crate::object_tree::PropertyAnimation::Transition {
                        state_ref,
                        animations,
                    }) => {
                        let state_tokens = compile_expression(state_ref, component);
                        let mut anim_expr = animations.iter().map(|a| {
                            let cond = compile_expression(
                                &a.condition(Expression::ReadLocalVariable {
                                    name: "state".into(),
                                    ty: state_ref.ty(),
                                }),
                                component,
                            );
                            let anim = property_animation_code(component, &a.animation);
                            format!("if ({}) {{ return {}; }}", remove_parentheses(&cond), anim)
                        });
                        format!(
                            "{}.set_animated_binding_for_transition({},
                            [this](uint64_t *start_time) -> sixtyfps::cbindgen_private::PropertyAnimation {{
                                [[maybe_unused]] auto self = this;
                                auto state = {};
                                *start_time = state.change_time;
                                {}
                                return {{}};
                            }});",
                            prop_access,
                            binding_code,
                            state_tokens,
                            anim_expr.join(" ")
                        )
                    }
                    None => format!("{}.set_binding({});", prop_access, binding_code),
                }
            }
        });
    }
}

fn handle_item(elem: &ElementRc, field_access: Access, main_struct: &mut Struct) {
    let item = elem.borrow();
    main_struct.members.push((
        field_access,
        Declaration::Var(Var {
            ty: format!(
                "sixtyfps::cbindgen_private::{}",
                ident(&item.base_type.as_native().class_name)
            ),
            name: ident(&item.id).into_owned(),
            init: Some("{}".to_owned()),
            ..Default::default()
        }),
    ));
}

fn handle_repeater(
    repeated: &RepeatedElementInfo,
    base_component: &Rc<Component>,
    parent_component: &Rc<Component>,
    repeater_count: i32,
    component_struct: &mut Struct,
    init: &mut Vec<String>,
    children_visitor_cases: &mut Vec<String>,
    repeated_input_branch: &mut Vec<String>,
    layout_repeater_code: &mut Vec<String>,
    diag: &mut BuildDiagnostics,
) {
    let parent_element = base_component.parent_element.upgrade().unwrap();
    let repeater_id = format!("repeater_{}", ident(&parent_element.borrow().id));

    let mut model = compile_expression(&repeated.model, parent_component);
    if repeated.is_conditional_element {
        // bool converts to int
        // FIXME: don't do a heap allocation here
        model = format!("std::make_shared<sixtyfps::private_api::IntModel>({})", model)
    };

    // FIXME: optimize  if repeated.model.is_constant()
    init.push(format!(
        "self->{repeater_id}.set_model_binding([self] {{ (void)self; return {model}; }});",
        repeater_id = repeater_id,
        model = model,
    ));

    if let Some(listview) = &repeated.is_listview {
        let vp_y = access_named_reference(&listview.viewport_y, parent_component, "self");
        let vp_h = access_named_reference(&listview.viewport_height, parent_component, "self");
        let lv_h = access_named_reference(&listview.listview_height, parent_component, "self");
        let vp_w = access_named_reference(&listview.viewport_width, parent_component, "self");
        let lv_w = access_named_reference(&listview.listview_width, parent_component, "self");

        let ensure_updated = format!(
            "self->{}.ensure_updated_listview(self, &{}, &{}, &{}, {}.get(), {}.get());",
            repeater_id, vp_w, vp_h, vp_y, lv_w, lv_h
        );

        children_visitor_cases.push(format!(
            "\n        case {i}: {{
                {e_u}
                return self->{id}.visit(order, visitor);
            }}",
            i = repeater_count,
            e_u = ensure_updated,
            id = repeater_id,
        ));

        layout_repeater_code.push(ensure_updated)
    } else {
        children_visitor_cases.push(format!(
            "\n        case {i}: {{
                self->{id}.ensure_updated(self);
                return self->{id}.visit(order, visitor);
            }}",
            id = repeater_id,
            i = repeater_count,
        ));

        layout_repeater_code.push(format!("self->{}.ensure_updated(self);", repeater_id));
    }

    repeated_input_branch.push(format!(
        "\n        case {i}: return self->{id}.item_at(rep_index);",
        i = repeater_count,
        id = repeater_id,
    ));

    component_struct.members.push((
        Access::Private,
        Declaration::Var(Var {
            ty: format!(
                "sixtyfps::private_api::Repeater<class {}, {}>",
                component_id(base_component),
                model_data_type(&parent_element, diag)
            ),
            name: repeater_id,
            ..Default::default()
        }),
    ));
}

/// Returns the text of the C++ code produced by the given root component
pub fn generate(doc: &Document, diag: &mut BuildDiagnostics) -> Option<impl std::fmt::Display> {
    let mut file = File::default();

    file.includes.push("<array>".into());
    file.includes.push("<limits>".into());
    file.includes.push("<cstdlib>".into()); // TODO: ideally only include this if needed (by to_float)
    file.includes.push("<cmath>".into()); // TODO: ideally only include this if needed (by floor/ceil/round)
    file.includes.push("<sixtyfps.h>".into());

    file.declarations.extend(doc.root_component.embedded_file_resources.borrow().iter().map(
        |(path, id)| {
            let file = crate::fileaccess::load_file(std::path::Path::new(path)).unwrap(); // embedding pass ensured that the file exists
            let data = file.read();

            let mut init = "{ ".to_string();

            use std::fmt::Write;

            for (index, byte) in data.iter().enumerate() {
                if index > 0 {
                    init.push(',');
                }
                write!(&mut init, "0x{:x}", byte).unwrap();
                if index % 16 == 0 {
                    init.push('\n');
                }
            }

            init.push_str("}");

            Declaration::Var(Var {
                ty: "inline uint8_t".into(),
                name: format!("sfps_embedded_resource_{}", id),
                array_size: Some(data.len()),
                init: Some(init),
            })
        },
    ));

    // Forward-declare the root so that sub-components can access singletons, the window, etc.
    file.declarations.push(Declaration::Struct(Struct {
        name: component_id(&doc.root_component),
        ..Default::default()
    }));

    for ty in doc.root_component.used_types.borrow().structs.iter() {
        if let Type::Struct { fields, name: Some(name), node: Some(_) } = ty {
            generate_struct(&mut file, name, fields, diag);
        }
    }

    for sub_comp in doc.root_component.used_types.borrow().sub_components.iter() {
        generate_component(&mut file, sub_comp, &doc.root_component, diag, None);
    }

    for glob in doc
        .root_component
        .used_types
        .borrow()
        .globals
        .iter()
        .filter(|glob| glob.requires_code_generation())
    {
        generate_component(&mut file, glob, &doc.root_component, diag, None);

        if glob.visible_in_public_api() {
            file.definitions.extend(glob.global_aliases().into_iter().map(|name| {
                Declaration::TypeAlias(TypeAlias {
                    old_name: ident(&glob.root_element.borrow().id).into_owned(),
                    new_name: name,
                })
            }))
        }
    }

    generate_component(&mut file, &doc.root_component, &doc.root_component, diag, None);

    file.definitions.push(Declaration::Var(Var{
        ty: format!(
            "[[maybe_unused]] constexpr sixtyfps::private_api::VersionCheckHelper<{}, {}, {}>",
            env!("CARGO_PKG_VERSION_MAJOR"),
            env!("CARGO_PKG_VERSION_MINOR"),
            env!("CARGO_PKG_VERSION_PATCH")),
        name: "THE_SAME_VERSION_MUST_BE_USED_FOR_THE_COMPILER_AND_THE_RUNTIME".into(),
        init: Some("sixtyfps::private_api::VersionCheckHelper<int(sixtyfps::private_api::VersionCheck::Major), int(sixtyfps::private_api::VersionCheck::Minor), int(sixtyfps::private_api::VersionCheck::Patch)>()".into()),
        ..Default::default()
    }));

    if diag.has_error() {
        None
    } else {
        Some(file)
    }
}

fn generate_struct(
    file: &mut File,
    name: &str,
    fields: &BTreeMap<String, Type>,
    diag: &mut BuildDiagnostics,
) {
    let mut operator_eq = String::new();
    let mut members = fields
        .iter()
        .map(|(name, t)| {
            use std::fmt::Write;
            write!(operator_eq, " && a.{0} == b.{0}", ident(name)).unwrap();
            (
                Access::Public,
                Declaration::Var(Var {
                    ty: t.cpp_type().unwrap_or_else(|| {
                        diag.push_error(
                            format!("Cannot map {} to a C++ type", t),
                            &Option::<crate::parser::SyntaxNode>::None,
                        );
                        Default::default()
                    }),
                    name: ident(name).into_owned(),
                    ..Default::default()
                }),
            )
        })
        .collect::<Vec<_>>();
    members.sort_unstable_by(|a, b| match (&a.1, &b.1) {
        (Declaration::Var(a), Declaration::Var(b)) => a.name.cmp(&b.name),
        _ => unreachable!(),
    });
    members.push((
        Access::Public,
        Declaration::Function(Function {
            name: "operator==".to_owned(),
            signature: format!("(const {0} &a, const {0} &b) -> bool", name),
            is_friend: true,
            statements: Some(vec![format!("return true{};", operator_eq)]),
            ..Function::default()
        }),
    ));
    members.push((
        Access::Public,
        Declaration::Function(Function {
            name: "operator!=".to_owned(),
            signature: format!("(const {0} &a, const {0} &b) -> bool", name),
            is_friend: true,
            statements: Some(vec!["return !(a == b);".into()]),
            ..Function::default()
        }),
    ));
    file.declarations.push(Declaration::Struct(Struct {
        name: name.into(),
        members,
        ..Default::default()
    }))
}

/// Generate the component in `file`.
///
/// `sub_components`, if Some, will be filled with all the sub component which needs to be added as friends
fn generate_component(
    file: &mut File,
    component: &Rc<Component>,
    root_component: &Rc<Component>,
    diag: &mut BuildDiagnostics,
    mut sub_components: Option<&mut Vec<String>>,
) {
    let component_id = component_id(component);
    let mut component_struct = Struct { name: component_id.clone(), ..Default::default() };

    let is_child_component = component.parent_element.upgrade().is_some();
    let is_sub_component = component.is_sub_component();

    component_struct.friends.extend(
        component
            .used_types
            .borrow()
            .sub_components
            .iter()
            .map(|sub_component| self::component_id(&sub_component)),
    );

    for c in component.popup_windows.borrow().iter() {
        let mut friends = vec![self::component_id(&c.component)];
        generate_component(file, &c.component, root_component, diag, Some(&mut friends));
        if let Some(sub_components) = sub_components.as_mut() {
            sub_components.extend_from_slice(friends.as_slice());
        }
        component_struct.friends.append(&mut friends);
    }

    let expose_property = |property: &PropertyDeclaration| -> bool {
        if component.is_global() || component.is_root_component.get() {
            property.expose_in_public_api
        } else {
            false
        }
    };

    let field_access = if !component.is_root_component.get() || component.is_global() {
        Access::Public
    } else {
        Access::Private
    };

    let mut init = vec!["[[maybe_unused]] auto self = this;".into()];

    for (prop_name, property_decl) in component.root_element.borrow().property_declarations.iter() {
        let cpp_name = ident(prop_name);
        let access = if let Some(alias) = &property_decl.is_alias {
            access_named_reference(alias, component, "this")
        } else {
            format!("this->{}", cpp_name)
        };

        let ty = if let Type::Callback { args, return_type } = &property_decl.property_type {
            let param_types =
                args.iter().map(|t| get_cpp_type(t, property_decl, diag)).collect::<Vec<_>>();
            let return_type = return_type
                .as_ref()
                .map_or("void".into(), |t| get_cpp_type(t, property_decl, diag));
            if expose_property(property_decl) {
                let callback_emitter = vec![format!(
                    "return {}.call({});",
                    access,
                    (0..args.len()).map(|i| format!("arg_{}", i)).join(", ")
                )];
                component_struct.members.push((
                    Access::Public,
                    Declaration::Function(Function {
                        name: format!("invoke_{}", cpp_name),
                        signature: format!(
                            "({}) const -> {}",
                            param_types
                                .iter()
                                .enumerate()
                                .map(|(i, ty)| format!("{} arg_{}", ty, i))
                                .join(", "),
                            return_type
                        ),
                        statements: Some(callback_emitter),
                        ..Default::default()
                    }),
                ));
                component_struct.members.push((
                    Access::Public,
                    Declaration::Function(Function {
                        name: format!("on_{}", cpp_name),
                        template_parameters: Some("typename Functor".into()),
                        signature: "(Functor && callback_handler) const".into(),
                        statements: Some(vec![format!(
                            "{}.set_handler(std::forward<Functor>(callback_handler));",
                            access
                        )]),
                        ..Default::default()
                    }),
                ));
            }
            format!("sixtyfps::private_api::Callback<{}({})>", return_type, param_types.join(", "))
        } else {
            let cpp_type = get_cpp_type(&property_decl.property_type, property_decl, diag);

            if expose_property(property_decl) {
                let prop_getter: Vec<String> = vec![format!("return {}.get();", access)];
                component_struct.members.push((
                    Access::Public,
                    Declaration::Function(Function {
                        name: format!("get_{}", cpp_name),
                        signature: format!("() const -> {}", cpp_type),
                        statements: Some(prop_getter),
                        ..Default::default()
                    }),
                ));

                let set_value = if let Some(alias) = &property_decl.is_alias {
                    property_set_value_code(component, &alias.element(), alias.name(), "value")
                } else {
                    property_set_value_code(component, &component.root_element, prop_name, "value")
                };

                let prop_setter: Vec<String> = vec![
                    "[[maybe_unused]] auto self = this;".into(),
                    format!("{}.{};", access, set_value),
                ];
                component_struct.members.push((
                    Access::Public,
                    Declaration::Function(Function {
                        name: format!("set_{}", cpp_name),
                        signature: format!("(const {} &value) const", cpp_type),
                        statements: Some(prop_setter),
                        ..Default::default()
                    }),
                ));
            }
            format!("sixtyfps::private_api::Property<{}>", cpp_type)
        };

        if is_sub_component {
            component_struct.members.push((
                Access::Public,
                Declaration::Function(Function {
                    name: format!("get_{}", &cpp_name),
                    signature: "()".to_owned(),
                    statements: Some(vec![format!("return &{};", access)]),
                    ..Default::default()
                }),
            ));
        }
        if property_decl.is_alias.is_none() {
            component_struct.members.push((
                field_access,
                Declaration::Var(Var { ty, name: cpp_name.into_owned(), ..Default::default() }),
            ));
        }
    }

    let mut constructor_arguments = String::new();
    let mut constructor_member_initializers = vec![];

    if component.is_root_component.get() || is_child_component {
        let mut window_init = None;
        let mut access = Access::Private;

        if component.is_root_component.get() {
            window_init = Some("sixtyfps::Window{sixtyfps::private_api::WindowRc()}".into());
            // FIXME: many of the different component bindings need to access this
            access = Access::Public;
        } else {
            constructor_member_initializers
                .push("m_window(parent->m_window.window_handle())".into());
        }

        component_struct.members.push((
            access,
            Declaration::Var(Var {
                ty: "sixtyfps::Window".into(),
                name: "m_window".into(),
                init: window_init,
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            access,
            Declaration::Var(Var {
                ty: format!(
                    "vtable::VWeak<sixtyfps::private_api::ComponentVTable, {}>",
                    component_id
                ),
                name: "self_weak".into(),
                ..Var::default()
            }),
        ));
    }

    if let Some(parent_element) = component.parent_element.upgrade() {
        if parent_element.borrow().repeated.as_ref().map_or(false, |r| !r.is_conditional_element) {
            let cpp_model_data_type = model_data_type(&parent_element, diag);
            component_struct.members.push((
                Access::Private,
                Declaration::Var(Var {
                    ty: "sixtyfps::private_api::Property<int>".into(),
                    name: "index".into(),
                    ..Default::default()
                }),
            ));

            component_struct.members.push((
                Access::Private,
                Declaration::Var(Var {
                    ty: format!("sixtyfps::private_api::Property<{}>", cpp_model_data_type),
                    name: "model_data".into(),
                    ..Default::default()
                }),
            ));

            let update_statements = vec!["index.set(i);".into(), "model_data.set(data);".into()];
            component_struct.members.push((
                Access::Public, // Because Repeater accesses it
                Declaration::Function(Function {
                    name: "update_data".into(),
                    signature: format!(
                        "(int i, const {} &data) const -> void",
                        cpp_model_data_type
                    ),
                    statements: Some(update_statements),
                    ..Function::default()
                }),
            ));
        } else if parent_element.borrow().repeated.is_some() {
            component_struct.members.push((
                Access::Public, // Because Repeater accesses it
                Declaration::Function(Function {
                    name: "update_data".into(),
                    signature: "(int, int) const -> void".into(),
                    statements: Some(vec![]),
                    ..Function::default()
                }),
            ));
        }
        let parent_component_id = self::component_id(
            &component
                .parent_element
                .upgrade()
                .unwrap()
                .borrow()
                .enclosing_component
                .upgrade()
                .unwrap(),
        );
        let parent_type = format!("class {} const *", parent_component_id);
        constructor_arguments = format!("{} parent", parent_type);
        init.push("this->parent = parent;".into());
        component_struct.members.push((
            Access::Public, // Because Repeater accesses it
            Declaration::Var(Var {
                ty: parent_type,
                name: "parent".into(),
                init: Some("nullptr".to_owned()),
                ..Default::default()
            }),
        ));
        component_struct.friends.push(parent_component_id);

        if parent_element.borrow().repeated.as_ref().map_or(false, |r| r.is_listview.is_some()) {
            let p_y = access_member(&component.root_element, "y", component, "this");
            let p_height = access_member(&component.root_element, "height", component, "this");
            let p_width = access_member(&component.root_element, "width", component, "this");

            component_struct.members.push((
                Access::Public, // Because Repeater accesses it
                Declaration::Function(Function {
                    name: "listview_layout".into(),
                    signature:
                        "(float *offset_y, const sixtyfps::private_api::Property<float> *viewport_width) const -> void"
                            .to_owned(),
                    statements: Some(vec![
                        "float vp_w = viewport_width->get();".to_owned(),

                        format!("{}.set(*offset_y);", p_y), // FIXME: shouldn't that be handled by apply layout?
                        format!("*offset_y += {}.get();", p_height),
                        format!("float w = {}.get();", p_width),
                        "if (vp_w < w)".to_owned(),
                        "    viewport_width->set(w);".to_owned(),
                    ]),
                    ..Function::default()
                }),
            ));
        } else if parent_element.borrow().repeated.is_some() {
            component_struct.members.push((
                Access::Public, // Because Repeater accesses it
                Declaration::Function(Function {
                    name: "box_layout_data".into(),
                    signature: "(sixtyfps::Orientation o) const -> sixtyfps::BoxLayoutCellData".to_owned(),
                    statements: Some(vec!["return { layout_info({&static_vtable, const_cast<void *>(static_cast<const void *>(this))}, o) };".into()]),

                    ..Function::default()
                }),
            ));
        }
    }

    if component.is_root_component.get() {
        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "show".into(),
                signature: "()".into(),
                statements: Some(vec!["m_window.show();".into()]),
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "hide".into(),
                signature: "()".into(),
                statements: Some(vec!["m_window.hide();".into()]),
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "window".into(),
                signature: "() const -> sixtyfps::Window&".into(),
                statements: Some(vec![format!(
                    "return const_cast<{} *>(this)->m_window;",
                    component_struct.name
                )]),
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "run".into(),
                signature: "()".into(),
                statements: Some(vec![
                    "show();".into(),
                    "sixtyfps::run_event_loop();".into(),
                    "hide();".into(),
                ]),
                ..Default::default()
            }),
        ));

        init.push("self->m_window.window_handle().init_items(this, item_tree());".into());

        component_struct.friends.push("sixtyfps::private_api::WindowRc".into());
    }

    let mut children_visitor_cases = vec![];
    let mut repeated_input_branch = vec![];
    let mut repeater_layout_code = vec![];
    let mut tree_array = vec![];
    let mut repeater_count = 0;

    #[derive(Default)]
    struct SubTreeState {
        offsetof_prefix: String, // offsetof(App, sub_component) + offsetof(SubComponent, sub_sub_component) + ...
        field_prefix: String,    // sub_component.sub_sub_componet
    }

    super::build_item_tree(
        component,
        SubTreeState::default(),
        &mut |state: &SubTreeState,
              component: &Rc<Component>,
              item_rc: &ElementRc,
              children_offset,
              parent_index| {
            let item = item_rc.borrow();
            if item.base_type == Type::Void {
                assert!(component.is_global());
            } else if item.repeated.is_some() {
                tree_array.push(format!(
                    "sixtyfps::private_api::make_dyn_node({}, {})",
                    repeater_count, parent_index
                ));
                repeater_count += 1;
            } else if let Type::Native(native_class) = &item.base_type {
                if item.is_flickable_viewport {
                    tree_array.push(format!(
                        "sixtyfps::private_api::make_item_node({}offsetof({}, {}) + offsetof(sixtyfps::cbindgen_private::Flickable, viewport), SIXTYFPS_GET_ITEM_VTABLE(RectangleVTable), {}, {}, {})",
                        state.offsetof_prefix,
                        &self::component_id(component),
                        ident(&crate::object_tree::find_parent_element(item_rc).unwrap().borrow().id),
                        item.children.len(),
                        children_offset,
                        parent_index,
                    ));
                } else {
                    tree_array.push(format!(
                        "sixtyfps::private_api::make_item_node({}offsetof({}, {}), {}, {}, {}, {})",
                        state.offsetof_prefix,
                        &self::component_id(component),
                        ident(&item.id),
                        native_class.cpp_vtable_getter,
                        item.children.len(),
                        children_offset,
                        parent_index,
                    ));
                }
            }
        },
        |state, sub_component, item_rc| {
            let item = item_rc.borrow();
            let field_prefix = format!("{}{}.", state.field_prefix, self::ident(&item.id));
            let offsetof_prefix = format!(
                "{}offsetof({}, {}) + ",
                state.offsetof_prefix,
                &self::component_id(sub_component),
                ident(&item.id)
            );
            SubTreeState { offsetof_prefix, field_prefix }
        },
    );

    let mut repeater_count = 0;

    crate::object_tree::recurse_elem_level_order(&component.root_element, &mut |item_rc| {
        let item = item_rc.borrow();
        if item.base_type == Type::Void {
            assert!(component.is_global());
        } else if let Some(repeated) = &item.repeated {
            let base_component = item.base_type.as_component();
            let mut friends = Vec::new();
            generate_component(file, base_component, root_component, diag, Some(&mut friends));
            if let Some(sub_components) = sub_components.as_mut() {
                sub_components.extend_from_slice(friends.as_slice());
                sub_components.push(self::component_id(base_component))
            }
            component_struct.friends.append(&mut friends);
            component_struct.friends.push(self::component_id(base_component));
            handle_repeater(
                repeated,
                base_component,
                component,
                repeater_count,
                &mut component_struct,
                &mut init,
                &mut children_visitor_cases,
                &mut repeated_input_branch,
                &mut repeater_layout_code,
                diag,
            );
            repeater_count += 1;
        } else if let Type::Native(_) = &item.base_type {
            handle_item(item_rc, field_access, &mut component_struct);
        } else if let Type::Component(sub_component) = &item.base_type {
            let class_name = self::component_id(&sub_component);

            let member_name = ident(&item.id).into_owned();
            let parent_index = if is_sub_component { "item_index_start + " } else { "" };

            let root_ptr = if is_sub_component { "root" } else { "this" };

            constructor_member_initializers.push(format!(
                "{member_name}{{{root_ptr}, {parent_index}{local_index}}}",
                root_ptr = root_ptr,
                member_name = member_name,
                parent_index = parent_index,
                local_index = item.item_index.get().unwrap()
            ));

            init.push(format!("{}.init();", member_name));

            component_struct.members.push((
                field_access,
                Declaration::Var(Var { ty: class_name, name: member_name, ..Default::default() }),
            ));
        }
    });

    super::handle_property_bindings_init(component, |elem, prop, binding| {
        handle_property_binding(elem, prop, binding, &mut init)
    });

    if is_child_component || component.is_root_component.get() {
        let maybe_constructor_param = if constructor_arguments.is_empty() { "" } else { "parent" };

        let mut create_code = vec![
            format!("auto self_rc = vtable::VRc<sixtyfps::private_api::ComponentVTable, {0}>::make({1});", component_id, maybe_constructor_param),
            format!("auto self = const_cast<{0} *>(&*self_rc);", component_id),
            "self->self_weak = vtable::VWeak(self_rc);".into(),
        ];

        if component.is_root_component.get() {
            create_code.push(
                "self->m_window.window_handle().set_component(**self->self_weak.lock());".into(),
            );
        }

        create_code.extend(
            component.setup_code.borrow().iter().map(|code| compile_expression(code, component)),
        );
        create_code
            .push(format!("return sixtyfps::ComponentHandle<{0}>{{ self_rc }};", component_id));

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "create".into(),
                signature: format!(
                    "({}) -> sixtyfps::ComponentHandle<{}>",
                    constructor_arguments, component_id
                ),
                statements: Some(create_code),
                is_static: true,
                ..Default::default()
            }),
        ));

        let mut destructor = vec!["[[maybe_unused]] auto self = this;".to_owned()];

        if is_child_component {
            destructor.push("if (!parent) return;".to_owned())
        }

        destructor
            .push("m_window.window_handle().free_graphics_resources(this, item_tree());".into());

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: format!("~{}", component_id),
                signature: "()".to_owned(),
                is_constructor_or_destructor: true,
                statements: Some(destructor),
                ..Default::default()
            }),
        ));

        generate_component_vtable(
            &mut component_struct,
            component_id.clone(),
            component,
            children_visitor_cases,
            tree_array,
            file,
        );
    }

    if is_sub_component {
        let root_ptr_type = format!("{} *", self::component_id(root_component));

        constructor_arguments =
            format!("{} root, [[maybe_unused]] uintptr_t item_index_start", root_ptr_type);

        constructor_member_initializers.push("m_window(root->m_window.window_handle())".into());
        constructor_member_initializers.push("m_root(root)".into());

        component_struct.members.push((
            Access::Private,
            Declaration::Var(Var {
                ty: "sixtyfps::Window".into(),
                name: "m_window".into(),
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            Access::Private,
            Declaration::Var(Var {
                ty: root_ptr_type,
                name: "m_root".to_owned(),
                ..Default::default()
            }),
        ));

        let root_element = component.root_element.borrow();
        let get_root_item = if root_element.sub_component().is_some() {
            format!("{}.root_item()", ident(&root_element.id))
        } else {
            format!("&{}", ident(&root_element.id))
        };
        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "root_item".to_owned(),
                signature: "()".into(),
                statements: Some(vec![format!("return {};", get_root_item)]),
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "layout_info".into(),
                signature:
                    "(sixtyfps::Orientation o, sixtyfps::private_api::WindowRc *window_handle) -> sixtyfps::LayoutInfo"
                        .into(),
                statements: Some(layout_info_function_body(
                    &component,
                    "auto self = this;".to_owned(),
                    Some("window_handle"),
                )),
                ..Default::default()
            }),
        ));

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "init".into(),
                signature: "()".into(),
                statements: Some(std::mem::take(&mut init)),
                ..Default::default()
            }),
        ))
    }

    component_struct.members.push((
        if !component.is_global() && !is_sub_component { Access::Private } else { Access::Public },
        Declaration::Function(Function {
            name: component_id,
            signature: format!("({})", constructor_arguments),
            is_constructor_or_destructor: true,
            statements: Some(init),
            constructor_member_initializers,
            ..Default::default()
        }),
    ));

    let used_types = component.used_types.borrow();

    let global_field_name = |glob| format!("global_{}", self::component_id(glob));

    for glob in used_types.globals.iter() {
        let ty = match &glob.root_element.borrow().base_type {
            Type::Void => self::component_id(glob),
            Type::Builtin(b) => {
                format!("sixtyfps::cbindgen_private::{}", b.native_class.class_name)
            }
            _ => unreachable!(),
        };

        component_struct.members.push((
            Access::Private,
            Declaration::Var(Var {
                ty: format!("std::shared_ptr<{}>", ty),
                name: global_field_name(glob),
                init: Some(format!("std::make_shared<{}>()", ty)),
                ..Default::default()
            }),
        ));
    }
    let mut global_accessor_function_body = Vec::new();

    for glob in used_types
        .globals
        .iter()
        .filter(|glob| glob.visible_in_public_api() && glob.requires_code_generation())
    {
        let mut accessor_statement = String::new();

        if !global_accessor_function_body.is_empty() {
            accessor_statement.push_str("else ");
        }

        accessor_statement.push_str(&format!(
            "if constexpr(std::is_same_v<T, {}>) {{ return *{}.get(); }}",
            self::component_id(glob),
            global_field_name(glob)
        ));

        global_accessor_function_body.push(accessor_statement);
    }

    if !global_accessor_function_body.is_empty() {
        global_accessor_function_body.push(
            "else { static_assert(!sizeof(T*), \"The type is not global/or exported\"); }".into(),
        );

        component_struct.members.push((
            Access::Public,
            Declaration::Function(Function {
                name: "global".into(),
                signature: "() const -> const T&".into(),
                statements: Some(global_accessor_function_body),
                template_parameters: Some("typename T".into()),
                ..Default::default()
            }),
        ));
    }

    file.definitions.extend(component_struct.extract_definitions().collect::<Vec<_>>());
    file.declarations.push(Declaration::Struct(component_struct));
}

fn generate_component_vtable(
    component_struct: &mut Struct,
    component_id: String,
    component: &Rc<Component>,
    children_visitor_cases: Vec<String>,
    tree_array: Vec<String>,
    file: &mut File,
) {
    component_struct
        .friends
        .push(format!("vtable::VRc<sixtyfps::private_api::ComponentVTable, {}>", component_id));
    component_struct.members.push((
        Access::Private,
        Declaration::Function(Function {
            name: "visit_children".into(),
            signature: "(sixtyfps::private_api::ComponentRef component, intptr_t index, sixtyfps::private_api::TraversalOrder order, sixtyfps::private_api::ItemVisitorRefMut visitor) -> int64_t".into(),
            is_static: true,
            statements: Some(vec![
                "static const auto dyn_visit = [] (const uint8_t *base,  [[maybe_unused]] sixtyfps::private_api::TraversalOrder order, [[maybe_unused]] sixtyfps::private_api::ItemVisitorRefMut visitor, uintptr_t dyn_index) -> int64_t {".to_owned(),
                format!("    [[maybe_unused]] auto self = reinterpret_cast<const {}*>(base);", component_id),
                format!("    switch(dyn_index) {{ {} }};", children_visitor_cases.join("")),
                "    std::abort();\n};".to_owned(),
                format!("auto self_rc = reinterpret_cast<const {}*>(component.instance)->self_weak.lock()->into_dyn();", component_id),
                "return sixtyfps::cbindgen_private::sixtyfps_visit_item_tree(&self_rc, item_tree() , index, order, visitor, dyn_visit);".to_owned(),
            ]),
            ..Default::default()
        }),
    ));
    component_struct.members.push((
        Access::Private,
        Declaration::Function(Function {
            name: "get_item_ref".into(),
            signature: "(sixtyfps::private_api::ComponentRef component, uintptr_t index) -> sixtyfps::private_api::ItemRef".into(),
            is_static: true,
            statements: Some(vec![
                "return sixtyfps::private_api::get_item_ref(component, item_tree(), index);".to_owned(),
            ]),
            ..Default::default()
        }),
    ));
    let parent_item_from_parent_component = if let Some(parent_index) =
        component.parent_element.upgrade().and_then(|e| e.borrow().item_index.get().copied())
    {
        format!(
            "   *result = sixtyfps::private_api::parent_item(self->parent->self_weak.into_dyn(), self->parent->item_tree(), {});",
            parent_index,
        )
    } else {
        "".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 *result) -> void".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,
                "   return;".into(),
                "}".into(),
                "*result = 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 {
            name: "item_tree".into(),
            signature: "() -> sixtyfps::Slice<sixtyfps::private_api::ItemTreeNode>".into(),
            is_static: true,
            statements: Some(vec![
                "static const sixtyfps::private_api::ItemTreeNode children[] {".to_owned(),
                format!("    {} }};", tree_array.join(", \n")),
                "return { const_cast<sixtyfps::private_api::ItemTreeNode*>(children), std::size(children) };"
                    .to_owned(),
            ]),
            ..Default::default()
        }),
    ));
    component_struct.members.push((
        Access::Private,
        Declaration::Function(Function {
            name: "layout_info".into(),
            signature:
                "([[maybe_unused]] sixtyfps::private_api::ComponentRef component, sixtyfps::Orientation o) -> sixtyfps::LayoutInfo"
                    .into(),
            is_static: true,
            statements: Some(layout_info_function_body(&component, format!(
                "[[maybe_unused]] auto self = reinterpret_cast<const {}*>(component.instance);",
                component_id
            ), None)),
            ..Default::default()
        }),
    ));
    component_struct.members.push((
        Access::Public,
        Declaration::Var(Var {
            ty: "static const sixtyfps::private_api::ComponentVTable".to_owned(),
            name: "static_vtable".to_owned(),
            ..Default::default()
        }),
    ));
    let root_elem = component.root_element.borrow();
    let get_root_item_ref = if let Type::Component(_) = root_elem.base_type {
        format!("return this->{id}.root_item();", id = ident(&root_elem.id))
    } else {
        format!(
            "return {{ {vt}, const_cast<decltype(this->{id})*>(&this->{id}) }};",
            vt = root_elem.base_type.as_native().cpp_vtable_getter,
            id = ident(&root_elem.id)
        )
    };
    component_struct.members.push((
        Access::Public,
        Declaration::Function(Function {
            name: "root_item".into(),
            signature: "() const -> sixtyfps::private_api::ItemRef".into(),
            statements: Some(vec![get_root_item_ref]),
            ..Default::default()
        }),
    ));
    file.definitions.push(Declaration::Var(Var {
        ty: "const sixtyfps::private_api::ComponentVTable".to_owned(),
        name: format!("{}::static_vtable", component_id),
        init: Some(format!(
            "{{ visit_children, get_item_ref, parent_item,  layout_info, sixtyfps::private_api::drop_in_place<{}>, sixtyfps::private_api::dealloc }}",
            component_id)
        ),
        ..Default::default()
    }));
}

fn component_id(component: &Rc<Component>) -> String {
    if component.is_global() {
        ident(&component.root_element.borrow().id).into_owned()
    } else if component.id.is_empty() {
        format!("Component_{}", ident(&component.root_element.borrow().id))
    } else {
        ident(&component.id).into_owned()
    }
}

fn model_data_type(parent_element: &ElementRc, diag: &mut BuildDiagnostics) -> String {
    if parent_element.borrow().repeated.as_ref().unwrap().is_conditional_element {
        return "int".into();
    }
    let model_data_type = crate::expression_tree::Expression::RepeaterModelReference {
        element: Rc::downgrade(parent_element),
    }
    .ty();
    model_data_type.cpp_type().unwrap_or_else(|| {
        diag.push_error_with_span(
            format!("Cannot map property type {} to C++", model_data_type),
            parent_element
                .borrow()
                .node
                .as_ref()
                .map(|n| n.to_source_location())
                .unwrap_or_default(),
        );

        String::default()
    })
}

/// Returns the code that can access the given property (but without the set or get)
///
/// to be used like:
/// ```ignore
/// let access = access_member(...);
/// format!("{}.get()", access)
/// ```
fn access_member(
    element: &ElementRc,
    name: &str,
    component: &Rc<Component>,
    component_cpp: &str,
) -> String {
    let e = element.borrow();
    let enclosing_component = e.enclosing_component.upgrade().unwrap();
    if Rc::ptr_eq(component, &enclosing_component) {
        if e.property_declarations.contains_key(name) || name.is_empty() || component.is_global() {
            format!("{}->{}", component_cpp, ident(name))
        } else if e.is_flickable_viewport {
            format!(
                "{}->{}.viewport.{}",
                component_cpp,
                ident(&crate::object_tree::find_parent_element(element).unwrap().borrow().id),
                ident(name)
            )
        } else if let Some(sub_component) = e.sub_component() {
            if sub_component.root_element.borrow().property_declarations.contains_key(name) {
                format!("(*{}->{}.get_{}())", component_cpp, ident(&e.id), ident(name))
            } else {
                access_member(
                    &sub_component.root_element,
                    name,
                    sub_component,
                    &format!("(&{}->{})", component_cpp, ident(&e.id),),
                )
            }
        } else {
            format!("{}->{}.{}", component_cpp, ident(&e.id), ident(name))
        }
    } else if enclosing_component.is_global() {
        let mut top_level_component = component.clone();
        let mut component_cpp = component_cpp.to_owned();
        while let Some(p) = top_level_component.parent_element.upgrade() {
            top_level_component = p.borrow().enclosing_component.upgrade().unwrap();
            component_cpp = format!("{}->parent", component_cpp);
        }
        if top_level_component.is_sub_component() {
            component_cpp = format!("{}->m_root", component_cpp);
        }
        let global_comp =
            format!("{}->global_{}", component_cpp, component_id(&enclosing_component));
        access_member(element, name, &enclosing_component, &global_comp)
    } else {
        access_member(
            element,
            name,
            &component
                .parent_element
                .upgrade()
                .unwrap()
                .borrow()
                .enclosing_component
                .upgrade()
                .unwrap(),
            &format!("{}->parent", component_cpp),
        )
    }
}

/// Call access_member  for a NamedReference
fn access_named_reference(
    nr: &NamedReference,
    component: &Rc<Component>,
    component_cpp: &str,
) -> String {
    access_member(&nr.element(), nr.name(), component, component_cpp)
}

/// Returns the code that can access the component of the given element
fn access_element_component<'a>(
    element: &ElementRc,
    current_component: &Rc<Component>,
    component_cpp: &'a str,
) -> Cow<'a, str> {
    let e = element.borrow();
    let enclosing_component = e.enclosing_component.upgrade().unwrap();
    if Rc::ptr_eq(current_component, &enclosing_component) {
        component_cpp.into()
    } else {
        access_element_component(
            element,
            &current_component
                .parent_element
                .upgrade()
                .unwrap()
                .borrow()
                .enclosing_component
                .upgrade()
                .unwrap(),
            &format!("{}->parent", component_cpp),
        )
        .to_string()
        .into()
    }
}

fn compile_expression(
    expr: &crate::expression_tree::Expression,
    component: &Rc<Component>,
) -> String {
    match expr {
        Expression::StringLiteral(s) => {
            format!(r#"sixtyfps::SharedString(u8"{}")"#, escape_string(s.as_str()))
        }
        Expression::NumberLiteral(n, unit) => {
            let num = unit.normalize(*n);
            if num > 1_000_000_000. {
                // If the numbers are too big, decimal notation will give too many digit
                format!("{:+e}", num)
            } else {
                num.to_string()
            }
        }
        Expression::BoolLiteral(b) => b.to_string(),
        Expression::PropertyReference(nr) => {
            let access =
                access_named_reference(nr, component, "self");
            format!(r#"{}.get()"#, access)
        }
        Expression::CallbackReference(nr) => format!(
            "{}.call",
            access_named_reference(nr, component, "self")
        ),
        Expression::BuiltinFunctionReference(funcref, _) => match funcref {
            BuiltinFunction::GetWindowScaleFactor => {
                "self->m_window.window_handle().scale_factor".into()
            }
            BuiltinFunction::Debug => {
                "[](auto... args){ (std::cout << ... << args) << std::endl; return nullptr; }"
                    .into()
            }
            BuiltinFunction::Mod => "[](auto a1, auto a2){ return static_cast<int>(a1) % static_cast<int>(a2); }".into(),
            BuiltinFunction::Round => "std::round".into(),
            BuiltinFunction::Ceil => "std::ceil".into(),
            BuiltinFunction::Floor => "std::floor".into(),
            BuiltinFunction::Sqrt => "std::sqrt".into(),
            BuiltinFunction::Abs => "std::abs".into(),
            BuiltinFunction::Sin => format!("[](float a){{ return std::sin(a * {}); }}", std::f32::consts::PI / 180.),
            BuiltinFunction::Cos => format!("[](float a){{ return std::cos(a * {}); }}", std::f32::consts::PI / 180.),
            BuiltinFunction::Tan => format!("[](float a){{ return std::tan(a * {}); }}", std::f32::consts::PI / 180.),
            BuiltinFunction::ASin => format!("[](float a){{ return std::asin(a) / {}; }}", std::f32::consts::PI / 180.),
            BuiltinFunction::ACos => format!("[](float a){{ return std::acos(a) / {}; }}", std::f32::consts::PI / 180.),
            BuiltinFunction::ATan => format!("[](float a){{ return std::atan(a) / {}; }}", std::f32::consts::PI / 180.),
            BuiltinFunction::SetFocusItem => {
                "self->m_window.window_handle().set_focus_item".into()
            }
            BuiltinFunction::ShowPopupWindow => {
                "self->m_window.window_handle().show_popup".into()
            }

           /*  std::from_chars is unfortunately not yet implemented in gcc
            BuiltinFunction::StringIsFloat => {
                "[](const auto &a){ double v; auto r = std::from_chars(std::begin(a), std::end(a), v); return r.ptr == std::end(a); }"
                    .into()
            }
            BuiltinFunction::StringToFloat => {
                "[](const auto &a){ double v; auto r = std::from_chars(std::begin(a), std::end(a), v); return r.ptr == std::end(a) ? v : 0; }"
                    .into()
            }*/
            BuiltinFunction::StringIsFloat => {
                "[](const auto &a){ auto e1 = std::end(a); auto e2 = const_cast<char*>(e1); std::strtod(std::begin(a), &e2); return e1 == e2; }"
                    .into()
            }
            BuiltinFunction::StringToFloat => {
                "[](const auto &a){ auto e1 = std::end(a); auto e2 = const_cast<char*>(e1); auto r = std::strtod(std::begin(a), &e2); return e1 == e2 ? r : 0; }"
                    .into()
            }
            BuiltinFunction::ImplicitLayoutInfo(_) => {
                unreachable!()
            }
            BuiltinFunction::ColorBrighter => {
                "[](const auto &color, float factor) { return color.brighter(factor); }".into()
            }
            BuiltinFunction::ColorDarker => {
                "[](const auto &color, float factor) { return color.darker(factor); }".into()
            }
            BuiltinFunction::ImageSize => {
                "[](const sixtyfps::Image &img) { return img.size(); }".into()
            }
            BuiltinFunction::ArrayLength => {
                "[](const auto &model) { (*model).track_row_count_changes(); return (*model).row_count(); }".into()
            }
            BuiltinFunction::Rgb => {
                "[](int r, int g, int b, float a) {{ return sixtyfps::Color::from_argb_uint8(std::clamp(a * 255., 0., 255.), std::clamp(r, 0, 255), std::clamp(g, 0, 255), std::clamp(b, 0, 255)); }}".into()
            }
            BuiltinFunction::RegisterCustomFontByPath => {
                panic!("internal error: RegisterCustomFontByPath can only be evaluated from within a FunctionCall expression")
            }
            BuiltinFunction::RegisterCustomFontByMemory => {
                panic!("internal error: RegisterCustomFontByMemory can only be evaluated from within a FunctionCall expression")
            }
        },
        Expression::ElementReference(_) => todo!("Element references are only supported in the context of built-in function calls at the moment"),
        Expression::MemberFunction { .. } => panic!("member function expressions must not appear in the code generator anymore"),
        Expression::BuiltinMacroReference { .. } => panic!("macro expressions must not appear in the code generator anymore"),
        Expression::RepeaterIndexReference { element } => {
            let access = access_member(
                &element.upgrade().unwrap().borrow().base_type.as_component().root_element,
                "",
                component,
                "self",
            );
            format!(r#"{}index.get()"#, access)
        }
        Expression::RepeaterModelReference { element } => {
            let access = access_member(
                &element.upgrade().unwrap().borrow().base_type.as_component().root_element,
                "",
                component,
                "self",
            );
            format!(r#"{}model_data.get()"#, access)
        }
        Expression::FunctionParameterReference { index, .. } => format!("arg_{}", index),
        Expression::StoreLocalVariable { name, value } => {
            format!("auto {} = {};", ident(name), compile_expression(value, component))
        }
        Expression::ReadLocalVariable { name, .. } => ident(name).into_owned(),
        Expression::StructFieldAccess { base, name } => match base.ty() {
            Type::Struct { fields, name : None, .. } => {
                let index = fields
                    .keys()
                    .position(|k| k == name)
                    .expect("Expression::ObjectAccess: Cannot find a key in an object");
                format!("std::get<{}>({})", index, compile_expression(base, component))
            }
            Type::Struct{..} => {
                format!("{}.{}", compile_expression(base, component), ident(name))
            }
            _ => panic!("Expression::ObjectAccess's base expression is not an Object type"),
        },
        Expression::Cast { from, to } => {
            let f = compile_expression(&*from, component);
            match (from.ty(), to) {
                (Type::Float32, Type::String) | (Type::Int32, Type::String) => {
                    format!("sixtyfps::SharedString::from_number({})", f)
                }
                (Type::Float32, Type::Model) | (Type::Int32, Type::Model) => {
                    format!("std::make_shared<sixtyfps::private_api::IntModel>({})", f)
                }
                (Type::Array(_), Type::Model) => f,
                (Type::Float32, Type::Color) => {
                    format!("sixtyfps::Color::from_argb_encoded({})", f)
                }
                (Type::Color, Type::Brush) => {
                    format!("sixtyfps::Brush({})", f)
                }
                (Type::Brush, Type::Color) => {
                    format!("{}.color()", f)
                }
                (Type::Struct { .. }, Type::Struct{ fields, name: Some(_), ..}) => {
                    format!(
                        "[&](const auto &o){{ {struct_name} s; auto& [{field_members}] = s; {fields}; return s; }}({obj})",
                        struct_name = to.cpp_type().unwrap(),
                        field_members = (0..fields.len()).map(|idx| format!("f_{}", idx)).join(", "),
                        obj = f,
                        fields = (0..fields.len())
                            .map(|idx| format!("f_{} = std::get<{}>(o)", idx, idx))
                            .join("; ")
                    )
                }
                _ => f,
            }
        }
        Expression::CodeBlock(sub) => {
            let len = sub.len();
            let mut x = sub.iter().enumerate().map(|(i, e)| {
                if i == len - 1 {
                    return_compile_expression(e, component, None) + ";"
                }
                else {
                    compile_expression(e, component)
                }

            });

            format!("[&]{{ {} }}()", x.join(";"))
        }
        Expression::FunctionCall { function, arguments, source_location: _  } => match &**function {
            Expression::BuiltinFunctionReference(BuiltinFunction::SetFocusItem, _) => {
                if arguments.len() != 1 {
                    panic!("internal error: incorrect argument count to SetFocusItem call");
                }
                if let Expression::ElementReference(focus_item) = &arguments[0] {
                    let focus_item = focus_item.upgrade().unwrap();
                    let component_ref = access_element_component(&focus_item, component, "self");
                    let focus_item = focus_item.borrow();
                    format!("self->m_window.window_handle().set_focus_item({}->self_weak.lock()->into_dyn(), {});", component_ref, focus_item.item_index.get().unwrap())
                } else {
                    panic!("internal error: argument to SetFocusItem must be an element")
                }
            }
            Expression::BuiltinFunctionReference(BuiltinFunction::ShowPopupWindow, _) => {
                if arguments.len() != 1 {
                    panic!("internal error: incorrect argument count to SetFocusItem call");
                }
                if let Expression::ElementReference(popup_window) = &arguments[0] {
                    let popup_window = popup_window.upgrade().unwrap();
                    let pop_comp = popup_window.borrow().enclosing_component.upgrade().unwrap();
                    let popup_window_rcid = component_id(&pop_comp);
                    let parent_component = pop_comp.parent_element.upgrade().unwrap().borrow().enclosing_component.upgrade().unwrap();
                    let popup_list = parent_component.popup_windows.borrow();
                    let popup = popup_list.iter().find(|p| Rc::ptr_eq(&p.component, &pop_comp)).unwrap();
                    let x = access_named_reference(&popup.x, component, "self");
                    let y = access_named_reference(&popup.y, component, "self");
                    let parent_component_ref = access_element_component(&popup.parent_element, component, "self");
                    format!(
                        "self->m_window.window_handle().show_popup<{}>(self, {{ {}.get(), {}.get() }}, {{ {}->self_weak.lock()->into_dyn(), {} }} );",
                        popup_window_rcid, x, y,
                        parent_component_ref, popup.parent_element.borrow().item_index.get().unwrap(),
                    )
                } else {
                    panic!("internal error: argument to SetFocusItem must be an element")
                }
            }
            Expression::BuiltinFunctionReference(BuiltinFunction::ImplicitLayoutInfo(orientation), _) => {
                if arguments.len() != 1 {
                    panic!("internal error: incorrect argument count to ImplicitLayoutInfo call");
                }
                if let Expression::ElementReference(item) = &arguments[0] {
                    let item = item.upgrade().unwrap();
                    let item = item.borrow();
                    if item.sub_component().is_some() {
                        format!("self->{compo}.layout_info({o}, &m_window.window_handle())",
                            compo = ident(&item.id),
                            o = to_cpp_orientation(*orientation)
                        )
                    } else {
                        let native_item = item.base_type.as_native();
                        format!("{vt}->layouting_info({{{vt}, const_cast<sixtyfps::cbindgen_private::{ty}*>(&self->{id})}}, {o}, &m_window.window_handle())",
                            vt = native_item.cpp_vtable_getter,
                            ty = native_item.class_name,
                            id = ident(&item.id),
                            o = to_cpp_orientation(*orientation),
                        )
                    }
                } else {
                    panic!("internal error: argument to ImplicitLayoutInfo must be an element")
                }
            }
            Expression::BuiltinFunctionReference(BuiltinFunction::RegisterCustomFontByPath, _) => {
                if arguments.len() != 1 {
                    panic!("internal error: incorrect argument count to RegisterCustomFontByPath call");
                }
                if let Expression::StringLiteral(font_path) = &arguments[0] {
                    format!("sixtyfps::private_api::register_font_from_path(\"{}\");", escape_string(font_path))
                } else {
                    panic!("internal error: argument to RegisterCustomFontByPath must be a string literal")
                }
            }
            Expression::BuiltinFunctionReference(BuiltinFunction::RegisterCustomFontByMemory, _) => {
                if arguments.len() != 1 {
                    panic!("internal error: incorrect argument count to RegisterCustomFontByMemory call");
                }
                if let Expression::NumberLiteral(resource_id, _) = &arguments[0] {
                    let resource_id: usize = *resource_id as _;
                    let symbol = format!("sfps_embedded_resource_{}", resource_id);
                    format!("sixtyfps::private_api::register_font_from_data({}, std::size({}));", symbol, symbol)
                } else {
                    panic!("internal error: argument to RegisterCustomFontByMemory must be a number")
                }
            }
            _ => {
                let mut args = arguments.iter().map(|e| compile_expression(e, component));

                format!("{}({})", compile_expression(function, component), args.join(", "))
            }
        },
        Expression::SelfAssignment { lhs, rhs, op } => {
            let rhs = compile_expression(&*rhs, component);
            compile_assignment(lhs, *op, rhs, component)
        }
        Expression::BinaryExpression { lhs, rhs, op } => {
            let mut buffer = [0; 3];
            format!(
                "({lhs} {op} {rhs})",
                lhs = compile_expression(&*lhs, component),
                rhs = compile_expression(&*rhs, component),
                op = match op {
                    '=' => "==",
                    '!' => "!=",
                    '≤' => "<=",
                    '≥' => ">=",
                    '&' => "&&",
                    '|' => "||",
                    '/' => "/(double)",
                    _ => op.encode_utf8(&mut buffer),
                },
            )
        }
        Expression::UnaryOp { sub, op } => {
            format!("({op} {sub})", sub = compile_expression(&*sub, component), op = op,)
        }
        Expression::ImageReference { resource_ref, .. }  => {
            match resource_ref {
                crate::expression_tree::ImageReference::None => r#"sixtyfps::Image()"#.to_string(),
                crate::expression_tree::ImageReference::AbsolutePath(path) => format!(r#"sixtyfps::Image::load_from_path(sixtyfps::SharedString(u8"{}"))"#, escape_string(path.as_str())),
                crate::expression_tree::ImageReference::EmbeddedData { resource_id, extension } => {
                    let symbol = format!("sfps_embedded_resource_{}", resource_id);
                    format!(
                        r#"sixtyfps::Image(sixtyfps::cbindgen_private::types::ImageInner::EmbeddedData(sixtyfps::Slice<uint8_t>{{std::data({}), std::size({})}}, sixtyfps::Slice<uint8_t>{{const_cast<uint8_t *>(reinterpret_cast<const uint8_t *>(u8"{}")), {}}}))"#,
                        symbol, symbol, escape_string(extension), extension.as_bytes().len()
                    )
                }
            }
        }
        Expression::Condition { condition, true_expr, false_expr } => {
            let ty = expr.ty();
            let cond_code = compile_expression(condition, component);
            let cond_code = remove_parentheses(&cond_code);
            let true_code = return_compile_expression(true_expr, component, Some(&ty));
            let false_code = return_compile_expression(false_expr, component, Some(&ty));
            format!(
                r#"[&]() -> {} {{ if ({}) {{ {}; }} else {{ {}; }}}}()"#,
                ty.cpp_type().unwrap_or_else(|| "void".to_string()),
                cond_code,
                true_code,
                false_code
            )

        }
        Expression::Array { element_ty, values } => {
            let ty = element_ty.cpp_type().unwrap_or_else(|| "FIXME: report error".to_owned());
            format!(
                "std::make_shared<sixtyfps::private_api::ArrayModel<{count},{ty}>>({val})",
                count = values.len(),
                ty = ty,
                val = values
                    .iter()
                    .map(|e| format!(
                        "{ty} ( {expr} )",
                        expr = compile_expression(e, component),
                        ty = ty,
                    ))
                    .join(", ")
            )
        }
        Expression::Struct { ty, values } => {
            if let Type::Struct{fields, ..} = ty {
                let mut elem = fields.keys().map(|k| {
                    values
                        .get(k)
                        .map(|e| compile_expression(e, component))
                        .unwrap_or_else(|| "(Error: missing member in object)".to_owned())
                });
                format!("{}{{{}}}", ty.cpp_type().unwrap(), elem.join(", "))
            } else {
                panic!("Expression::Object is not a Type::Object")
            }
        }
        Expression::PathElements { elements } => compile_path(elements, component),
        Expression::EasingCurve(EasingCurve::Linear) => "sixtyfps::cbindgen_private::EasingCurve()".into(),
        Expression::EasingCurve(EasingCurve::CubicBezier(a, b, c, d)) => format!(
            "sixtyfps::cbindgen_private::EasingCurve(sixtyfps::cbindgen_private::EasingCurve::Tag::CubicBezier, {}, {}, {}, {})",
            a, b, c, d
        ),
        Expression::LinearGradient{angle, stops} => {
            let angle = compile_expression(angle, component);
            let mut stops_it = stops.iter().map(|(color, stop)| {
                let color = compile_expression(color, component);
                let position = compile_expression(stop, component);
                format!("sixtyfps::private_api::GradientStop{{ {}, {}, }}", color, position)
            });
            format!(
                "[&] {{ const sixtyfps::private_api::GradientStop stops[] = {{ {} }}; return sixtyfps::Brush(sixtyfps::private_api::LinearGradientBrush({}, stops, {})); }}()",
                stops_it.join(", "), angle, stops.len()
            )
        }
        Expression::EnumerationValue(value) => {
            format!("sixtyfps::cbindgen_private::{}::{}", value.enumeration.name, ident(&value.to_string()))
        }
        Expression::ReturnStatement(Some(expr)) => format!(
            "throw sixtyfps::private_api::ReturnWrapper<{}>({})",
            expr.ty().cpp_type().unwrap_or_default(),
            compile_expression(expr, component)
        ),
        Expression::ReturnStatement(None) => "throw sixtyfps::private_api::ReturnWrapper<void>()".to_owned(),
        Expression::LayoutCacheAccess { layout_cache_prop, index, repeater_index } => {
            let cache = access_named_reference(layout_cache_prop, component, "self");
            if let Some(ri) = repeater_index {
                format!("sixtyfps::private_api::layout_cache_access({}.get(), {}, {})", cache, index, compile_expression(ri, component))
            } else {
                format!("{}.get()[{}]", cache, index)
            }
        }
        Expression::ComputeLayoutInfo(Layout::GridLayout(layout), o) => {
            let (padding, spacing) = generate_layout_padding_and_spacing(&layout.geometry, *o, component);
            let cells = grid_layout_cell_data(layout, *o, component);
            format!("[&] {{ \
                    const auto padding = {};\
                    sixtyfps::GridLayoutCellData cells[] = {{ {} }}; \
                    const sixtyfps::Slice<sixtyfps::GridLayoutCellData> slice{{ cells, std::size(cells)}}; \
                    return sixtyfps::sixtyfps_grid_layout_info(slice, {}, &padding);\
                }}()",
                padding, cells, spacing
            )
        }
        Expression::ComputeLayoutInfo(Layout::BoxLayout(layout), o) => {
            let (padding, spacing) = generate_layout_padding_and_spacing(&layout.geometry, *o, component);
            let (cells, alignment) = box_layout_data(layout, *o, component, None);
            let call = if *o == layout.orientation {
                format!("sixtyfps_box_layout_info(slice, {}, &padding, {})", spacing, alignment)
            } else {
                "sixtyfps_box_layout_info_ortho(slice, &padding)".to_string()
            };
            format!("[&] {{ \
                    const auto padding = {};\
                    {}\
                    const sixtyfps::Slice<sixtyfps::BoxLayoutCellData> slice{{ std::data(cells), std::size(cells)}}; \
                    return sixtyfps::cbindgen_private::{};\
                }}()",
                padding, cells, call
            )
        }
        Expression::ComputeLayoutInfo(Layout::PathLayout(_), _) => unimplemented!(),
        Expression::SolveLayout(Layout::GridLayout(layout), o) => {
            let (padding, spacing) = generate_layout_padding_and_spacing(&layout.geometry, *o, component);
            let cells = grid_layout_cell_data(layout, *o, component);
            let size = layout_geometry_size(&layout.geometry.rect, *o, component);
            let dialog = if let (Some(button_roles), Orientation::Horizontal) = (&layout.dialog_button_roles, *o) {
                format!("sixtyfps::cbindgen_private::DialogButtonRole roles[] = {{ {r} }};\
                        sixtyfps::cbindgen_private::sixtyfps_reorder_dialog_button_layout(cells,\
                            sixtyfps::Slice<sixtyfps::cbindgen_private::DialogButtonRole>{{ roles, std::size(roles) }});\
                        ",
                    r = button_roles.iter().map(|r| format!("sixtyfps::cbindgen_private::DialogButtonRole::{}", r)).join(", ")
                )
            } else { String::new() };
            format!("[&] {{\
                    const auto padding = {p};\
                    sixtyfps::GridLayoutCellData cells[] = {{ {c} }};\
                    {dialog}
                    const sixtyfps::Slice<sixtyfps::GridLayoutCellData> slice{{ cells, std::size(cells)}};\
                    const sixtyfps::GridLayoutData grid {{ {sz},  {s}, &padding, slice }};\
                    sixtyfps::SharedVector<float> result;\
                    sixtyfps::sixtyfps_solve_grid_layout(&grid, &result);\
                    return result;\
                }}()",
                dialog = dialog, p = padding, c = cells, s = spacing, sz = size
            )
        }
        Expression::SolveLayout(Layout::BoxLayout(layout), o) => {
            let (padding, spacing) = generate_layout_padding_and_spacing(&layout.geometry, *o, component);
            let mut repeated_indices = Default::default();
            let mut repeated_indices_init = Default::default();
            let (cells, alignment) = box_layout_data(layout, *o, component, Some((&mut repeated_indices, &mut repeated_indices_init)));
            let size = layout_geometry_size(&layout.geometry.rect, *o, component);
            format!("[&] {{ \
                    {ri_init}\
                    const auto padding = {p};\
                    {c}\
                    const sixtyfps::Slice<sixtyfps::BoxLayoutCellData> slice{{ std::data(cells), std::size(cells)}}; \
                    sixtyfps::BoxLayoutData box {{ {sz}, {s}, &padding, {a}, slice }};
                    sixtyfps::SharedVector<float> result;
                    sixtyfps::sixtyfps_solve_box_layout(&box, {ri}, &result);\
                    return result;
                }}()",
                ri_init = repeated_indices_init, ri = repeated_indices,
                p = padding, c = cells, s = spacing, sz = size, a = alignment,
            )
        }
        Expression::SolveLayout(Layout::PathLayout(layout), _) => {
            let width = layout_geometry_size(&layout.rect, Orientation::Horizontal, component);
            let height = layout_geometry_size(&layout.rect, Orientation::Vertical, component);
            let elements = compile_path(&layout.path, component);
            let prop = |expr: &Option<NamedReference>| {
                if let Some(nr) = expr.as_ref() {
                    format!("{}.get()", access_named_reference(nr, component, "self"))
                } else {
                    "0.".into()
                }
            };
            // FIXME! repeater
            format!("[&] {{ \
                    const auto elements = {e};\
                    sixtyfps::PathLayoutData path {{ &elements, {c}, 0, 0, {w}, {h}, {o} }};
                    sixtyfps::SharedVector<float> result;
                    sixtyfps::sixtyfps_solve_path_layout(&path, {{}}, &result);\
                    return result;
                }}()",
                e = elements, c = layout.elements.len(), w = width, h = height, o = prop(&layout.offset_reference)
            )

        }
        Expression::Uncompiled(_) => panic!(),
        Expression::Invalid => "\n#error invalid expression\n".to_string(),
    }
}

fn compile_assignment(
    lhs: &Expression,
    op: char,
    rhs: String,
    component: &Rc<Component>,
) -> String {
    match lhs {
        Expression::PropertyReference(nr) => {
            let access = access_named_reference(nr, component, "self");
            let set = property_set_value_code(
                component,
                &nr.element(),
                nr.name(),
                &(if op == '=' { rhs } else { format!("{}.get() {} {}", access, op, rhs) }),
            );
            format!("{}.{}", access, set)
        }
        Expression::StructFieldAccess { base, name } => {
            let tmpobj = "tmpobj";
            let get_obj = compile_expression(base, component);
            let ty = base.ty();
            let member = match &ty {
                Type::Struct { fields, name: None, .. } => {
                    let index = fields
                        .keys()
                        .position(|k| k == name)
                        .expect("Expression::ObjectAccess: Cannot find a key in an object");
                    format!("std::get<{}>({})", index, tmpobj)
                }
                Type::Struct { .. } => format!("{}.{}", tmpobj, ident(name)),
                _ => panic!("Expression::ObjectAccess's base expression is not an Object type"),
            };
            let op = if op == '=' { ' ' } else { op };
            let new_value = format!(
                "[&]{{ auto {tmp} = {get}; {member} {op}= {rhs}; return {tmp}; }}()",
                tmp = tmpobj,
                get = get_obj,
                member = member,
                op = op,
                rhs = rhs,
            );
            compile_assignment(base, '=', new_value, component)
        }
        Expression::RepeaterModelReference { element } => {
            let element = element.upgrade().unwrap();
            let parent_component = element.borrow().base_type.as_component().clone();
            let repeater_access = access_member(
                &parent_component
                    .parent_element
                    .upgrade()
                    .unwrap()
                    .borrow()
                    .enclosing_component
                    .upgrade()
                    .unwrap()
                    .root_element,
                "",
                component,
                "self",
            );
            let index_access = access_member(&parent_component.root_element, "", component, "self");
            let repeater_id = format!("repeater_{}", ident(&element.borrow().id));
            if op == '=' {
                format!(
                    "{}{}.model_set_row_data({}index.get(), {})",
                    repeater_access, repeater_id, index_access, rhs
                )
            } else {
                format!(
                    "{}{}.model_set_row_data({}index.get(), {} {} {})",
                    repeater_access,
                    repeater_id,
                    index_access,
                    rhs,
                    op,
                    compile_expression(lhs, component)
                )
            }
        }
        _ => panic!("typechecking should make sure this was a PropertyReference"),
    }
}

fn grid_layout_cell_data(
    layout: &crate::layout::GridLayout,
    orientation: Orientation,
    component: &Rc<Component>,
) -> String {
    layout
        .elems
        .iter()
        .map(|c| {
            let (col_or_row, span) = c.col_or_row_and_span(orientation);
            format!(
                "sixtyfps::GridLayoutCellData {{ {}, {}, {} }}",
                col_or_row,
                span,
                get_layout_info(&c.item.element, component, &c.item.constraints, orientation, None),
            )
        })
        .join(", ")
}

/// Returns `(cells, alignment)`.
/// The repeated_indices initialize the repeated_indices (var, init_code)
fn box_layout_data(
    layout: &crate::layout::BoxLayout,
    orientation: Orientation,
    component: &Rc<Component>,
    mut repeated_indices: Option<(&mut String, &mut String)>,
) -> (String, String) {
    let alignment = if let Some(nr) = &layout.geometry.alignment {
        format!("{}.get()", access_named_reference(nr, component, "self"))
    } else {
        "{}".into()
    };

    let repeater_count =
        layout.elems.iter().filter(|i| i.element.borrow().repeated.is_some()).count();

    if repeater_count == 0 {
        let mut cells = layout.elems.iter().map(|li| {
            format!(
                "sixtyfps::BoxLayoutCellData{{ {} }}",
                get_layout_info(&li.element, component, &li.constraints, orientation, None)
            )
        });
        if let Some((ri, _)) = &mut repeated_indices {
            **ri = "{}".into();
        }
        (format!("sixtyfps::BoxLayoutCellData cells[] = {{ {} }};", cells.join(", ")), alignment)
    } else {
        let mut push_code = "std::vector<sixtyfps::BoxLayoutCellData> cells;".to_owned();
        if let Some((ri, init)) = &mut repeated_indices {
            **ri =
                "sixtyfps::Slice<unsigned int>{std::data(repeater_indices), std::size(repeater_indices)}"
                    .to_owned();
            **init = format!("std::array<unsigned int, {}> repeater_indices;", repeater_count * 2);
        }
        let mut repeater_idx = 0usize;
        for item in &layout.elems {
            if item.element.borrow().repeated.is_some() {
                push_code += &format!(
                    "self->repeater_{}.ensure_updated(self);",
                    ident(&item.element.borrow().id)
                );
                if repeated_indices.is_some() {
                    push_code += &format!("repeater_indices[{}] = cells.size();", repeater_idx * 2);
                    push_code += &format!(
                        "repeater_indices[{c}] = self->repeater_{id}.inner ? self->repeater_{id}.inner->data.size() : 0;",
                        c = repeater_idx * 2 + 1,
                        id = ident(&item.element.borrow().id)
                    );
                }
                repeater_idx += 1;
                push_code += &format!(
                    "if (self->repeater_{id}.inner) \
                        for (auto &&sub_comp : self->repeater_{id}.inner->data) \
                           cells.push_back((*sub_comp.ptr)->box_layout_data({o}));",
                    id = ident(&item.element.borrow().id),
                    o = to_cpp_orientation(orientation),
                );
            } else {
                push_code += &format!(
                    "cells.push_back({{ {} }});",
                    get_layout_info(&item.element, component, &item.constraints, orientation, None)
                );
            }
        }
        (push_code, alignment)
    }
}

fn generate_layout_padding_and_spacing(
    layout_geometry: &LayoutGeometry,
    orientation: Orientation,
    component: &Rc<Component>,
) -> (String, String) {
    let prop = |expr: Option<&NamedReference>| {
        if let Some(nr) = expr {
            format!("{}.get()", access_named_reference(nr, component, "self"))
        } else {
            "0.".into()
        }
    };
    let spacing = prop(layout_geometry.spacing.as_ref());
    let (begin, end) = layout_geometry.padding.begin_end(orientation);
    let padding = format!("sixtyfps::Padding {{ {}, {} }};", prop(begin), prop(end));
    (padding, spacing)
}

fn layout_geometry_size(
    rect: &LayoutRect,
    orientation: Orientation,
    component: &Rc<Component>,
) -> String {
    rect.size_reference(orientation).map_or_else(
        || "0.".into(),
        |nr| format!("{}.get()", access_named_reference(nr, component, "self")),
    )
}

fn get_layout_info(
    elem: &ElementRc,
    component: &Rc<Component>,
    constraints: &crate::layout::LayoutConstraints,
    orientation: Orientation,
    custom_window_handle_accessor: Option<&'_ str>,
) -> String {
    let window_handle = if let Some(custom_accessor) = custom_window_handle_accessor {
        custom_accessor
    } else {
        "&self->m_window.window_handle()"
    };
    let mut layout_info = if let Some(layout_info_prop) =
        &elem.borrow().layout_info_prop(orientation)
    {
        format!("{}.get()", access_named_reference(layout_info_prop, component, "self"))
    } else if elem.borrow().sub_component().is_some() {
        format!(
            "self->{id}.layout_info({o}, {window_handle})",
            id = ident(&elem.borrow().id),
            o = to_cpp_orientation(orientation),
            window_handle = window_handle
        )
    } else {
        format!(
            "{vt}->layouting_info({{{vt}, const_cast<sixtyfps::cbindgen_private::{ty}*>(&self->{id})}}, {o}, {window_handle})",
            vt = elem.borrow().base_type.as_native().cpp_vtable_getter,
            ty = elem.borrow().base_type.as_native().class_name,
            id = ident(&elem.borrow().id),
            o = to_cpp_orientation(orientation),
            window_handle = window_handle
        )
    };

    if constraints.has_explicit_restrictions() {
        layout_info = format!("[&]{{ auto layout_info = {};", layout_info);
        for (expr, name) in constraints.for_each_restrictions(orientation) {
            layout_info += &format!(
                " layout_info.{} = {}.get();",
                name,
                access_named_reference(expr, component, "self")
            );
        }
        layout_info += " return layout_info; }()";
    }
    layout_info
}

fn layout_info_function_body(
    component: &Rc<Component>,
    self_accessor: String,
    custom_window_accessor: Option<&'_ str>,
) -> Vec<String> {
    vec![
        self_accessor,
        format!(
            "if (o == sixtyfps::Orientation::Horizontal) return {};",
            get_layout_info(
                &component.root_element,
                component,
                &component.root_constraints.borrow(),
                Orientation::Horizontal,
                custom_window_accessor
            )
        ),
        format!(
            "else return {};",
            get_layout_info(
                &component.root_element,
                component,
                &component.root_constraints.borrow(),
                Orientation::Vertical,
                custom_window_accessor
            )
        ),
    ]
}

fn compile_path(path: &crate::expression_tree::Path, component: &Rc<Component>) -> String {
    match path {
        crate::expression_tree::Path::Elements(elements) => {
            let converted_elements: Vec<String> = elements
                .iter()
                .map(|element| {
                    let element_initializer = element
                        .element_type
                        .native_class
                        .cpp_type
                        .as_ref()
                        .map(|cpp_type| {
                            new_struct_with_bindings(cpp_type, &element.bindings, component)
                        })
                        .unwrap_or_default();
                    format!(
                        "sixtyfps::private_api::PathElement::{}({})",
                        element.element_type.native_class.class_name, element_initializer
                    )
                })
                .collect();
            format!(
                r#"[&](){{
                sixtyfps::private_api::PathElement elements[{}] = {{
                    {}
                }};
                return sixtyfps::private_api::PathData(&elements[0], std::size(elements));
            }}()"#,
                converted_elements.len(),
                converted_elements.join(",")
            )
        }
        crate::expression_tree::Path::Events(events) => {
            let (converted_events, converted_coordinates) = compile_path_events(events);
            format!(
                r#"[&](){{
                sixtyfps::private_api::PathEvent events[{}] = {{
                    {}
                }};
                sixtyfps::private_api::Point coordinates[{}] = {{
                    {}
                }};
                return sixtyfps::private_api::PathData(&events[0], std::size(events), &coordinates[0], std::size(coordinates));
            }}()"#,
                converted_events.len(),
                converted_events.join(","),
                converted_coordinates.len(),
                converted_coordinates.join(",")
            )
        }
    }
}

fn compile_path_events(events: &[crate::expression_tree::PathEvent]) -> (Vec<String>, Vec<String>) {
    use lyon_path::Event;

    let mut coordinates = Vec::new();

    let events = events
        .iter()
        .map(|event| match event {
            Event::Begin { at } => {
                coordinates.push(at);
                "sixtyfps::private_api::PathEvent::Begin"
            }
            Event::Line { from, to } => {
                coordinates.push(from);
                coordinates.push(to);
                "sixtyfps::private_api::PathEvent::Line"
            }
            Event::Quadratic { from, ctrl, to } => {
                coordinates.push(from);
                coordinates.push(ctrl);
                coordinates.push(to);
                "sixtyfps::private_api::PathEvent::Quadratic"
            }
            Event::Cubic { from, ctrl1, ctrl2, to } => {
                coordinates.push(from);
                coordinates.push(ctrl1);
                coordinates.push(ctrl2);
                coordinates.push(to);
                "sixtyfps::private_api::PathEvent::Cubic"
            }
            Event::End { close, .. } => {
                if *close {
                    "sixtyfps::private_api::PathEvent::EndClosed"
                } else {
                    "sixtyfps::private_api::PathEvent::EndOpen"
                }
            }
        })
        .map(String::from)
        .collect();

    let coordinates = coordinates
        .into_iter()
        .map(|pt| format!("sixtyfps::private_api::Point{{{}, {}}}", pt.x, pt.y))
        .collect();

    (events, coordinates)
}

/// Like compile_expression, but wrap inside a try{}catch{} block to intercept the return
fn compile_expression_wrap_return(expr: &Expression, component: &Rc<Component>) -> String {
    /// Return a type if there is any `return` in sub expressions
    fn return_type(expr: &Expression) -> Option<Type> {
        if let Expression::ReturnStatement(val) = expr {
            return Some(val.as_ref().map_or(Type::Void, |v| v.ty()));
        }
        let mut ret = None;
        expr.visit(|e| {
            if ret.is_none() {
                ret = return_type(e)
            }
        });
        ret
    }

    if let Some(ty) = return_type(expr) {
        if ty == Type::Void || ty == Type::Invalid {
            format!(
                "[&]{{ try {{ {}; }} catch(const sixtyfps::private_api::ReturnWrapper<void> &w) {{ }} }}()",
                compile_expression(expr, component)
            )
        } else {
            let cpp_ty = ty.cpp_type().unwrap_or_default();
            format!(
                "[&]() -> {} {{ try {{ {}; }} catch(const sixtyfps::private_api::ReturnWrapper<{}> &w) {{ return w.value; }} }}()",
                cpp_ty,
                return_compile_expression(expr, component, Some(&ty)),
                cpp_ty
            )
        }
    } else {
        compile_expression(expr, component)
    }
}

/// Like compile expression, but prepended with `return` if not void.
/// ret_type is the expecting type that should be returned with that return statement
fn return_compile_expression(
    expr: &Expression,
    component: &Rc<Component>,
    ret_type: Option<&Type>,
) -> String {
    let e = compile_expression(expr, component);
    if ret_type == Some(&Type::Void) || ret_type == Some(&Type::Invalid) {
        e
    } else {
        let ty = expr.ty();
        if ty == Type::Invalid && ret_type.is_some() {
            // e is unreachable so it probably throws. But we still need to return something to avoid a warning
            format!("{}; return {{}}", e)
        } else if ty == Type::Invalid || ty == Type::Void {
            e
        } else {
            format!("return {}", e)
        }
    }
}