i_slint_compiler/llr/

lower_expression.rs

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0

use std::cell::RefCell;
use std::collections::{BTreeMap, HashMap};
use std::rc::{Rc, Weak};

use smol_str::{SmolStr, format_smolstr};

use super::lower_layout_expression::{
    compute_box_layout_info, compute_flexbox_layout_info, compute_grid_layout_info,
    organize_grid_layout, solve_box_layout, solve_flexbox_layout, solve_grid_layout,
};
use super::lower_to_item_tree::{LoweredSubComponentMapping, LoweringState};
use super::{Animation, LocalMemberReference, MemberReference, PropertyIdx};
use crate::expression_tree::{BuiltinFunction, Callable, Expression as tree_Expression};
use crate::langtype::{BuiltinPrivateStruct, Struct, StructName, Type};
use crate::llr::ArrayOutput as llr_ArrayOutput;
use crate::llr::Expression as llr_Expression;
use crate::namedreference::NamedReference;
use crate::object_tree::{Element, ElementRc, PropertyAnimation};
use crate::typeregister::BUILTIN;

pub struct ExpressionLoweringCtxInner<'a> {
    pub component: &'a Rc<crate::object_tree::Component>,
    /// The mapping for the current component
    pub mapping: &'a LoweredSubComponentMapping,
    pub parent: Option<&'a ExpressionLoweringCtxInner<'a>>,
}
#[derive(derive_more::Deref)]
pub struct ExpressionLoweringCtx<'a> {
    pub state: &'a mut LoweringState,
    #[deref]
    pub inner: ExpressionLoweringCtxInner<'a>,
}

impl ExpressionLoweringCtx<'_> {
    pub fn map_property_reference(&self, from: &NamedReference) -> MemberReference {
        let element = from.element();
        let enclosing = &element.borrow().enclosing_component.upgrade().unwrap();
        let mut level = 0;
        let mut map = &self.inner;
        if !enclosing.is_global() {
            while !Rc::ptr_eq(enclosing, map.component) {
                map = map.parent.unwrap_or_else(|| {
                    panic!(
                        "Could not find component for property reference {from:?} in component {:?}. Started with enclosing={:?}",
                        self.component.id,
                        enclosing.id
                    )
                });
                level += 1;
            }
        }
        let mut r = map.mapping.map_property_reference(from, self.state);
        if let MemberReference::Relative { parent_level, .. } = &mut r {
            *parent_level += level;
        }
        r
    }
}

impl super::TypeResolutionContext for ExpressionLoweringCtx<'_> {
    fn property_ty(&self, _: &MemberReference) -> &Type {
        unimplemented!()
    }
}

pub fn lower_expression(
    expression: &tree_Expression,
    ctx: &mut ExpressionLoweringCtx<'_>,
) -> llr_Expression {
    match expression {
        tree_Expression::Invalid => {
            panic!("internal error, encountered invalid expression at code generation time")
        }
        tree_Expression::Uncompiled(_) => panic!(),
        tree_Expression::StringLiteral(s) => llr_Expression::StringLiteral(s.clone()),
        tree_Expression::NumberLiteral(n, unit) => {
            llr_Expression::NumberLiteral(unit.normalize(*n))
        }
        tree_Expression::BoolLiteral(b) => llr_Expression::BoolLiteral(*b),
        tree_Expression::PropertyReference(nr) => {
            llr_Expression::PropertyReference(ctx.map_property_reference(nr))
        }
        tree_Expression::ElementReference(e) => {
            let elem = e.upgrade().unwrap();
            let enclosing = elem.borrow().enclosing_component.upgrade().unwrap();
            // When within a ShowPopupMenu builtin function, this is a reference to the root of the menu item tree
            if Rc::ptr_eq(&elem, &enclosing.root_element)
                && let Some(idx) = ctx
                    .component
                    .menu_item_tree
                    .borrow()
                    .iter()
                    .position(|c| Rc::ptr_eq(c, &enclosing))
            {
                return llr_Expression::NumberLiteral(idx as _);
            }

            // We map an element reference to a reference to the property "" inside that native item
            llr_Expression::PropertyReference(
                ctx.map_property_reference(&NamedReference::new(&elem, SmolStr::default())),
            )
        }
        tree_Expression::RepeaterIndexReference { element } => llr_Expression::PropertyReference(
            repeater_special_property(element, ctx.component, PropertyIdx::REPEATER_INDEX),
        ),
        tree_Expression::RepeaterModelReference { element } => llr_Expression::PropertyReference(
            repeater_special_property(element, ctx.component, PropertyIdx::REPEATER_DATA),
        ),
        tree_Expression::FunctionParameterReference { index, .. } => {
            llr_Expression::FunctionParameterReference { index: *index }
        }
        tree_Expression::StoreLocalVariable { name, value } => llr_Expression::StoreLocalVariable {
            name: name.clone(),
            value: Box::new(lower_expression(value, ctx)),
        },
        tree_Expression::ReadLocalVariable { name, ty } => {
            llr_Expression::ReadLocalVariable { name: name.clone(), ty: ty.clone() }
        }
        tree_Expression::StructFieldAccess { base, name } => llr_Expression::StructFieldAccess {
            base: Box::new(lower_expression(base, ctx)),
            name: name.clone(),
        },
        tree_Expression::ArrayIndex { array, index } => llr_Expression::ArrayIndex {
            array: Box::new(lower_expression(array, ctx)),
            index: Box::new(lower_expression(index, ctx)),
        },
        tree_Expression::Cast { from, to } => {
            llr_Expression::Cast { from: Box::new(lower_expression(from, ctx)), to: to.clone() }
        }
        tree_Expression::CodeBlock(expr) => {
            llr_Expression::CodeBlock(expr.iter().map(|e| lower_expression(e, ctx)).collect::<_>())
        }
        tree_Expression::FunctionCall { function, arguments, .. } => match function {
            Callable::Builtin(BuiltinFunction::RestartTimer) => lower_restart_timer(arguments),
            Callable::Builtin(BuiltinFunction::ShowPopupWindow) => {
                lower_show_popup_window(arguments, ctx)
            }
            Callable::Builtin(BuiltinFunction::ClosePopupWindow) => {
                lower_close_popup_window(arguments, ctx)
            }
            Callable::Builtin(f) => {
                let mut arguments =
                    arguments.iter().map(|e| lower_expression(e, ctx)).collect::<Vec<_>>();
                // https://github.com/rust-lang/rust-clippy/issues/16191
                #[allow(clippy::collapsible_if)]
                if *f == BuiltinFunction::Translate {
                    if let llr_Expression::Array { output, .. } = &mut arguments[3] {
                        *output = llr_ArrayOutput::Slice;
                    }
                    #[cfg(feature = "bundle-translations")]
                    if let Some(translation_builder) = ctx.state.translation_builder.as_mut() {
                        return translation_builder.lower_translate_call(arguments);
                    }
                }
                if *f == BuiltinFunction::ParseMarkdown
                    && let Some(llr_Expression::Array { output, .. }) = &mut arguments.get_mut(1)
                {
                    *output = llr_ArrayOutput::Slice;
                }
                llr_Expression::BuiltinFunctionCall { function: f.clone(), arguments }
            }
            Callable::Callback(nr) => {
                let arguments = arguments.iter().map(|e| lower_expression(e, ctx)).collect::<_>();
                llr_Expression::CallBackCall { callback: ctx.map_property_reference(nr), arguments }
            }
            Callable::Function(nr)
                if nr
                    .element()
                    .borrow()
                    .native_class()
                    .is_some_and(|n| n.properties.contains_key(nr.name())) =>
            {
                llr_Expression::ItemMemberFunctionCall { function: ctx.map_property_reference(nr) }
            }
            Callable::Function(nr) => {
                let arguments = arguments.iter().map(|e| lower_expression(e, ctx)).collect::<_>();
                llr_Expression::FunctionCall { function: ctx.map_property_reference(nr), arguments }
            }
        },
        tree_Expression::SelfAssignment { lhs, rhs, op, .. } => {
            lower_assignment(lhs, rhs, *op, ctx)
        }
        tree_Expression::BinaryExpression { lhs, rhs, op } => llr_Expression::BinaryExpression {
            lhs: Box::new(lower_expression(lhs, ctx)),
            rhs: Box::new(lower_expression(rhs, ctx)),
            op: *op,
        },
        tree_Expression::UnaryOp { sub, op } => {
            llr_Expression::UnaryOp { sub: Box::new(lower_expression(sub, ctx)), op: *op }
        }
        tree_Expression::ImageReference { resource_ref, nine_slice, .. } => {
            llr_Expression::ImageReference {
                resource_ref: resource_ref.clone(),
                nine_slice: *nine_slice,
            }
        }
        tree_Expression::Condition { condition, true_expr, false_expr } => {
            let (true_ty, false_ty) = (true_expr.ty(), false_expr.ty());
            llr_Expression::Condition {
                condition: Box::new(lower_expression(condition, ctx)),
                true_expr: Box::new(lower_expression(true_expr, ctx)),
                false_expr: if false_ty == Type::Invalid
                    || false_ty == Type::Void
                    || true_ty == false_ty
                {
                    Box::new(lower_expression(false_expr, ctx))
                } else {
                    // Because the type of the Condition is based on the false expression, we need to insert a cast
                    Box::new(llr_Expression::Cast {
                        from: Box::new(lower_expression(false_expr, ctx)),
                        to: Type::Void,
                    })
                },
            }
        }
        tree_Expression::Array { element_ty, values } => llr_Expression::Array {
            element_ty: element_ty.clone(),
            values: values.iter().map(|e| lower_expression(e, ctx)).collect::<_>(),
            output: llr_ArrayOutput::Model,
        },
        tree_Expression::Struct { ty, values } => llr_Expression::Struct {
            ty: ty.clone(),
            values: values
                .iter()
                .map(|(s, e)| (s.clone(), lower_expression(e, ctx)))
                .collect::<_>(),
        },
        tree_Expression::PathData(data) => compile_path(data, ctx),
        tree_Expression::EasingCurve(x) => llr_Expression::EasingCurve(x.clone()),
        tree_Expression::LinearGradient { angle, stops } => llr_Expression::LinearGradient {
            angle: Box::new(lower_expression(angle, ctx)),
            stops: stops
                .iter()
                .map(|(a, b)| (lower_expression(a, ctx), lower_expression(b, ctx)))
                .collect::<_>(),
        },
        tree_Expression::RadialGradient { stops } => llr_Expression::RadialGradient {
            stops: stops
                .iter()
                .map(|(a, b)| (lower_expression(a, ctx), lower_expression(b, ctx)))
                .collect::<_>(),
        },
        tree_Expression::ConicGradient { from_angle, stops } => llr_Expression::ConicGradient {
            from_angle: Box::new(lower_expression(from_angle, ctx)),
            stops: stops
                .iter()
                .map(|(a, b)| (lower_expression(a, ctx), lower_expression(b, ctx)))
                .collect::<_>(),
        },
        tree_Expression::EnumerationValue(e) => llr_Expression::EnumerationValue(e.clone()),
        tree_Expression::Keys(ks) => llr_Expression::KeysLiteral(ks.clone()),
        tree_Expression::ReturnStatement(..) => {
            panic!("The remove return pass should have removed all return")
        }
        tree_Expression::LayoutCacheAccess {
            layout_cache_prop,
            index,
            repeater_index,
            entries_per_item,
        } => llr_Expression::LayoutCacheAccess {
            layout_cache_prop: ctx.map_property_reference(layout_cache_prop),
            index: *index,
            repeater_index: repeater_index.as_ref().map(|e| lower_expression(e, ctx).into()),
            entries_per_item: *entries_per_item,
        },
        tree_Expression::GridRepeaterCacheAccess {
            layout_cache_prop,
            index,
            repeater_index,
            stride,
            child_offset,
            inner_repeater_index,
            entries_per_item,
        } => llr_Expression::GridRepeaterCacheAccess {
            layout_cache_prop: ctx.map_property_reference(layout_cache_prop),
            index: *index,
            repeater_index: lower_expression(repeater_index, ctx).into(),
            stride: lower_expression(stride, ctx).into(),
            child_offset: *child_offset,
            inner_repeater_index: inner_repeater_index
                .as_ref()
                .map(|e| lower_expression(e, ctx).into()),
            entries_per_item: *entries_per_item,
        },
        tree_Expression::OrganizeGridLayout(l) => organize_grid_layout(l, ctx),
        tree_Expression::ComputeBoxLayoutInfo(l, o) => compute_box_layout_info(l, *o, ctx),
        tree_Expression::ComputeGridLayoutInfo {
            layout_organized_data_prop,
            layout,
            orientation,
        } => compute_grid_layout_info(layout_organized_data_prop, layout, *orientation, ctx),
        tree_Expression::SolveBoxLayout(l, o) => solve_box_layout(l, *o, ctx),
        tree_Expression::SolveGridLayout { layout_organized_data_prop, layout, orientation } => {
            solve_grid_layout(layout_organized_data_prop, layout, *orientation, ctx)
        }
        tree_Expression::SolveFlexboxLayout(l) => solve_flexbox_layout(l, ctx),
        tree_Expression::ComputeFlexboxLayoutInfo(l, o) => compute_flexbox_layout_info(l, *o, ctx),
        tree_Expression::MinMax { ty, op, lhs, rhs } => llr_Expression::MinMax {
            ty: ty.clone(),
            op: *op,
            lhs: Box::new(lower_expression(lhs, ctx)),
            rhs: Box::new(lower_expression(rhs, ctx)),
        },
        tree_Expression::EmptyComponentFactory => llr_Expression::EmptyComponentFactory,
        tree_Expression::DebugHook { expression, .. } => lower_expression(expression, ctx),
    }
}

fn lower_assignment(
    lhs: &tree_Expression,
    rhs: &tree_Expression,
    op: char,
    ctx: &mut ExpressionLoweringCtx,
) -> llr_Expression {
    match lhs {
        tree_Expression::PropertyReference(nr) => {
            let rhs = lower_expression(rhs, ctx);
            let property = ctx.map_property_reference(nr);
            let value = if op == '=' {
                rhs
            } else {
                llr_Expression::BinaryExpression {
                    lhs: llr_Expression::PropertyReference(property.clone()).into(),
                    rhs: rhs.into(),
                    op,
                }
            }
            .into();
            llr_Expression::PropertyAssignment { property, value }
        }
        tree_Expression::StructFieldAccess { base, name } => {
            let ty = base.ty();

            static COUNT: std::sync::atomic::AtomicUsize = std::sync::atomic::AtomicUsize::new(0);
            let unique_name = format_smolstr!(
                "struct_assignment{}",
                COUNT.fetch_add(1, std::sync::atomic::Ordering::Relaxed)
            );
            let s = tree_Expression::StoreLocalVariable {
                name: unique_name.clone(),
                value: base.clone(),
            };
            let lower_base =
                tree_Expression::ReadLocalVariable { name: unique_name, ty: ty.clone() };
            let mut values = HashMap::new();
            let Type::Struct(ty) = ty else { unreachable!() };

            for field in ty.fields.keys() {
                let e = if field != name {
                    tree_Expression::StructFieldAccess {
                        base: lower_base.clone().into(),
                        name: field.clone(),
                    }
                } else if op == '=' {
                    rhs.clone()
                } else {
                    tree_Expression::BinaryExpression {
                        lhs: tree_Expression::StructFieldAccess {
                            base: lower_base.clone().into(),
                            name: field.clone(),
                        }
                        .into(),
                        rhs: Box::new(rhs.clone()),
                        op,
                    }
                };
                values.insert(field.clone(), e);
            }

            let new_value =
                tree_Expression::CodeBlock(vec![s, tree_Expression::Struct { ty, values }]);
            lower_assignment(base, &new_value, '=', ctx)
        }
        tree_Expression::RepeaterModelReference { element } => {
            let rhs = lower_expression(rhs, ctx);
            let prop =
                repeater_special_property(element, ctx.component, PropertyIdx::REPEATER_DATA);

            let level = match &prop {
                MemberReference::Relative { parent_level, .. } => *parent_level,
                _ => 0,
            };

            let value = Box::new(if op == '=' {
                rhs
            } else {
                llr_Expression::BinaryExpression {
                    lhs: llr_Expression::PropertyReference(prop).into(),
                    rhs: rhs.into(),
                    op,
                }
            });

            llr_Expression::ModelDataAssignment { level, value }
        }
        tree_Expression::ArrayIndex { array, index } => {
            let rhs = lower_expression(rhs, ctx);
            let array = Box::new(lower_expression(array, ctx));
            let index = Box::new(lower_expression(index, ctx));
            let value = Box::new(if op == '=' {
                rhs
            } else {
                // FIXME: this will compute the index and the array twice:
                // Ideally we should store the index and the array in local variable
                llr_Expression::BinaryExpression {
                    lhs: llr_Expression::ArrayIndex { array: array.clone(), index: index.clone() }
                        .into(),
                    rhs: rhs.into(),
                    op,
                }
            });

            llr_Expression::ArrayIndexAssignment { array, index, value }
        }
        _ => panic!("not a rvalue"),
    }
}

pub fn repeater_special_property(
    element: &Weak<RefCell<Element>>,
    component: &Rc<crate::object_tree::Component>,
    property_index: PropertyIdx,
) -> MemberReference {
    let enclosing = element.upgrade().unwrap().borrow().enclosing_component.upgrade().unwrap();
    let mut parent_level = 0;
    let mut component = component.clone();
    while !Rc::ptr_eq(&enclosing, &component) {
        let parent_elem = component.parent_element().unwrap();
        component = parent_elem.borrow().enclosing_component.upgrade().unwrap();
        parent_level += 1;
    }
    MemberReference::Relative {
        parent_level: parent_level - 1,
        local_reference: LocalMemberReference {
            sub_component_path: Vec::new(),
            reference: property_index.into(),
        },
    }
}

fn lower_restart_timer(args: &[tree_Expression]) -> llr_Expression {
    if let [tree_Expression::ElementReference(e)] = args {
        let timer_element = e.upgrade().unwrap();
        let timer_comp = timer_element.borrow().enclosing_component.upgrade().unwrap();

        let timer_list = timer_comp.timers.borrow();
        let timer_index = timer_list
            .iter()
            .position(|t| Rc::ptr_eq(&t.element.upgrade().unwrap(), &timer_element))
            .unwrap();

        llr_Expression::BuiltinFunctionCall {
            function: BuiltinFunction::RestartTimer,
            arguments: vec![llr_Expression::NumberLiteral(timer_index as _)],
        }
    } else {
        panic!("invalid arguments to RestartTimer");
    }
}

fn lower_show_popup_window(
    args: &[tree_Expression],
    ctx: &mut ExpressionLoweringCtx,
) -> llr_Expression {
    if let [tree_Expression::ElementReference(e)] = args {
        let popup_window = e.upgrade().unwrap();
        let pop_comp = popup_window.borrow().enclosing_component.upgrade().unwrap();
        let parent_elem = pop_comp.parent_element().unwrap();
        let parent_component = parent_elem.borrow().enclosing_component.upgrade().unwrap();
        let popup_list = parent_component.popup_windows.borrow();
        let (popup_index, popup) = popup_list
            .iter()
            .enumerate()
            .find(|(_, p)| Rc::ptr_eq(&p.component, &pop_comp))
            .unwrap();
        let item_ref = lower_expression(
            &tree_Expression::ElementReference(Rc::downgrade(&popup.parent_element)),
            ctx,
        );

        llr_Expression::BuiltinFunctionCall {
            function: BuiltinFunction::ShowPopupWindow,
            arguments: vec![
                llr_Expression::NumberLiteral(popup_index as _),
                llr_Expression::EnumerationValue(popup.close_policy.clone()),
                item_ref,
            ],
        }
    } else {
        panic!("invalid arguments to ShowPopupWindow");
    }
}

fn lower_close_popup_window(
    args: &[tree_Expression],
    ctx: &mut ExpressionLoweringCtx,
) -> llr_Expression {
    if let [tree_Expression::ElementReference(e)] = args {
        let popup_window = e.upgrade().unwrap();
        let pop_comp = popup_window.borrow().enclosing_component.upgrade().unwrap();
        let parent_elem = pop_comp.parent_element().unwrap();
        let parent_component = parent_elem.borrow().enclosing_component.upgrade().unwrap();
        let popup_list = parent_component.popup_windows.borrow();
        let (popup_index, popup) = popup_list
            .iter()
            .enumerate()
            .find(|(_, p)| Rc::ptr_eq(&p.component, &pop_comp))
            .unwrap();
        let item_ref = lower_expression(
            &tree_Expression::ElementReference(Rc::downgrade(&popup.parent_element)),
            ctx,
        );

        llr_Expression::BuiltinFunctionCall {
            function: BuiltinFunction::ClosePopupWindow,
            arguments: vec![llr_Expression::NumberLiteral(popup_index as _), item_ref],
        }
    } else {
        panic!("invalid arguments to ShowPopupWindow");
    }
}

pub fn lower_animation(a: &PropertyAnimation, ctx: &mut ExpressionLoweringCtx<'_>) -> Animation {
    fn lower_animation_element(
        a: &ElementRc,
        ctx: &mut ExpressionLoweringCtx<'_>,
    ) -> llr_Expression {
        llr_Expression::Struct {
            values: animation_fields()
                .map(|(k, ty)| {
                    let e = a.borrow().bindings.get(&k).map_or_else(
                        || llr_Expression::default_value_for_type(&ty).unwrap(),
                        |v| lower_expression(&v.borrow().expression, ctx),
                    );
                    (k, e)
                })
                .collect::<_>(),
            ty: animation_ty(),
        }
    }

    fn animation_fields() -> impl Iterator<Item = (SmolStr, Type)> {
        IntoIterator::into_iter([
            (SmolStr::new_static("duration"), Type::Int32),
            (SmolStr::new_static("iteration-count"), Type::Float32),
            (
                SmolStr::new_static("direction"),
                Type::Enumeration(BUILTIN.with(|e| e.enums.AnimationDirection.clone())),
            ),
            (SmolStr::new_static("easing"), Type::Easing),
            (SmolStr::new_static("delay"), Type::Int32),
        ])
    }

    fn animation_ty() -> Rc<Struct> {
        Rc::new(Struct {
            fields: animation_fields().collect(),
            name: BuiltinPrivateStruct::PropertyAnimation.into(),
        })
    }

    match a {
        PropertyAnimation::Static(a) => Animation::Static(lower_animation_element(a, ctx)),
        PropertyAnimation::Transition { state_ref, animations } => {
            let set_state = llr_Expression::StoreLocalVariable {
                name: "state".into(),
                value: Box::new(lower_expression(state_ref, ctx)),
            };
            let animation_ty = Type::Struct(animation_ty());
            let mut get_anim = llr_Expression::default_value_for_type(&animation_ty).unwrap();
            for tr in animations.iter().rev() {
                let condition = lower_expression(
                    &tr.condition(tree_Expression::ReadLocalVariable {
                        name: "state".into(),
                        ty: state_ref.ty(),
                    }),
                    ctx,
                );
                get_anim = llr_Expression::Condition {
                    condition: Box::new(condition),
                    true_expr: Box::new(lower_animation_element(&tr.animation, ctx)),
                    false_expr: Box::new(get_anim),
                }
            }
            let result = llr_Expression::Struct {
                // This is going to be a tuple
                ty: Rc::new(Struct {
                    fields: IntoIterator::into_iter([
                        (SmolStr::new_static("0"), animation_ty),
                        // The type is an instant, which does not exist in our type system
                        (SmolStr::new_static("1"), Type::Invalid),
                    ])
                    .collect(),
                    name: StructName::None,
                }),
                values: IntoIterator::into_iter([
                    (SmolStr::new_static("0"), get_anim),
                    (
                        SmolStr::new_static("1"),
                        llr_Expression::StructFieldAccess {
                            base: llr_Expression::ReadLocalVariable {
                                name: "state".into(),
                                ty: state_ref.ty(),
                            }
                            .into(),
                            name: "change_time".into(),
                        },
                    ),
                ])
                .collect(),
            };
            Animation::Transition(llr_Expression::CodeBlock(vec![set_state, result]))
        }
    }
}

fn compile_path(
    path: &crate::expression_tree::Path,
    ctx: &mut ExpressionLoweringCtx,
) -> llr_Expression {
    fn llr_path_elements(elements: Vec<llr_Expression>) -> llr_Expression {
        llr_Expression::Cast {
            from: llr_Expression::Array {
                element_ty: crate::typeregister::path_element_type(),
                values: elements,
                output: llr_ArrayOutput::Slice,
            }
            .into(),
            to: Type::PathData,
        }
    }

    match path {
        crate::expression_tree::Path::Elements(elements) => {
            let converted_elements = elements
                .iter()
                .map(|element| {
                    let element_type = Rc::new(Struct {
                        fields: element
                            .element_type
                            .properties
                            .iter()
                            .map(|(k, v)| (k.clone(), v.ty.clone()))
                            .collect(),
                        name: StructName::BuiltinPrivate(
                            element
                                .element_type
                                .native_class
                                .builtin_struct
                                .clone()
                                .expect("path elements should have a native_type"),
                        ),
                    });

                    llr_Expression::Struct {
                        ty: element_type,
                        values: element
                            .element_type
                            .properties
                            .iter()
                            .map(|(element_field_name, element_property)| {
                                (
                                    element_field_name.clone(),
                                    element.bindings.get(element_field_name).map_or_else(
                                        || {
                                            llr_Expression::default_value_for_type(
                                                &element_property.ty,
                                            )
                                            .unwrap()
                                        },
                                        |expr| lower_expression(&expr.borrow().expression, ctx),
                                    ),
                                )
                            })
                            .collect(),
                    }
                })
                .collect();
            llr_path_elements(converted_elements)
        }
        crate::expression_tree::Path::Events(events, points) => {
            if events.is_empty() || points.is_empty() {
                return llr_path_elements(Vec::new());
            }

            let events: Vec<_> = events.iter().map(|event| lower_expression(event, ctx)).collect();

            let event_type = events.first().unwrap().ty(ctx);

            let points: Vec<_> = points.iter().map(|point| lower_expression(point, ctx)).collect();

            let point_type = points.first().unwrap().ty(ctx);

            llr_Expression::Cast {
                from: llr_Expression::Struct {
                    ty: Rc::new(Struct {
                        fields: IntoIterator::into_iter([
                            (SmolStr::new_static("events"), Type::Array(event_type.clone().into())),
                            (SmolStr::new_static("points"), Type::Array(point_type.clone().into())),
                        ])
                        .collect(),
                        name: StructName::None,
                    }),
                    values: IntoIterator::into_iter([
                        (
                            SmolStr::new_static("events"),
                            llr_Expression::Array {
                                element_ty: event_type,
                                values: events,
                                output: llr_ArrayOutput::Slice,
                            },
                        ),
                        (
                            SmolStr::new_static("points"),
                            llr_Expression::Array {
                                element_ty: point_type,
                                values: points,
                                output: llr_ArrayOutput::Slice,
                            },
                        ),
                    ])
                    .collect(),
                }
                .into(),
                to: Type::PathData,
            }
        }
        crate::expression_tree::Path::Commands(commands) => llr_Expression::Cast {
            from: lower_expression(commands, ctx).into(),
            to: Type::PathData,
        },
    }
}

pub fn make_struct(
    name: impl Into<StructName>,
    it: impl IntoIterator<Item = (&'static str, Type, llr_Expression)>,
) -> llr_Expression {
    let mut fields = BTreeMap::<SmolStr, Type>::new();
    let mut values = BTreeMap::<SmolStr, llr_Expression>::new();
    for (name, ty, expr) in it {
        fields.insert(SmolStr::new(name), ty);
        values.insert(SmolStr::new(name), expr);
    }

    llr_Expression::Struct { ty: Rc::new(Struct { fields, name: name.into() }), values }
}