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fix(transformer/class-properties): create temp var for class where re…
…quired
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crates/oxc_transformer/src/es2022/class_properties/class_bindings.rs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,103 @@ | ||
| use oxc_syntax::symbol::{SymbolFlags, SymbolId}; | ||
| use oxc_traverse::{BoundIdentifier, TraverseCtx}; | ||
|
|
||
| /// Store for bindings for class. | ||
| /// | ||
| /// 1. Existing binding for class name (if class has a name). | ||
| /// 2. Temp var `_Class`, which may or may not be required. | ||
| /// | ||
| /// Temp var is required in the following circumstances: | ||
| /// * Class expression has static properties. | ||
| /// e.g. `C = class { x = 1; }` | ||
| /// * Class declaration has static properties and one of the static prop's initializers contains: | ||
| /// a. `this` | ||
| /// e.g. `class C { x = this; }` | ||
| /// b. Reference to class name | ||
| /// e.g. `class C { x = C; }` | ||
| /// c. A private field referring to one of the class's static private props. | ||
| /// e.g. `class C { static #x; static y = obj.#x; }` | ||
| /// | ||
| /// An instance of `ClassBindings` is stored in main `ClassProperties` transform, and a 2nd is stored | ||
| /// in `PrivateProps` for the class, if the class has any private properties. | ||
| /// If the class has private props, the instance of `ClassBindings` in `PrivateProps` is the source | ||
| /// of truth. | ||
| /// | ||
| /// The logic for when transpiled private fields use a reference to class name or class temp var | ||
| /// is unfortunately rather complicated. | ||
| /// | ||
| /// Transpiled private fields referring to a static private prop use: | ||
| /// * Class name when field is within class body and class has a name | ||
| /// e.g. `class C { static #x; method() { return obj.#x; } }` | ||
| /// * Temp var when field is within class body and class has no name | ||
| /// e.g. `C = class { static #x; method() { return obj.#x; } }` | ||
| /// * Temp var when field is within a static prop initializer. | ||
| /// e.g. `class C { static #x; y = obj.#x; }` | ||
| /// | ||
| /// To cover all these cases, the meaning of `temp` binding here changes while traversing the class body. | ||
| /// [`ClassProperties::transform_class`] sets `temp` binding to be a copy of the `name` binding before | ||
| /// that traversal begins. So the name `temp` is misleading at that point. | ||
| /// | ||
| /// Debug assertions are used to make sure this complex logic is correct. | ||
| /// | ||
| /// [`ClassProperties::transform_class`]: super::ClassProperties::transform_class | ||
| #[derive(Default, Clone)] | ||
| pub(super) struct ClassBindings<'a> { | ||
| /// Binding for class name, if class has name | ||
| pub name: Option<BoundIdentifier<'a>>, | ||
| /// Temp var for class. | ||
| /// e.g. `_Class` in `_Class = class {}, _Class.x = 1, _Class` | ||
| pub temp: Option<BoundIdentifier<'a>>, | ||
| /// `true` if currently transforming static property initializers. | ||
| /// Only used in debug builds to check logic is correct. | ||
| #[cfg(debug_assertions)] | ||
| pub currently_transforming_static_property_initializers: bool, | ||
| } | ||
|
|
||
| impl<'a> ClassBindings<'a> { | ||
| /// Create `ClassBindings`. | ||
| pub fn new( | ||
| name_binding: Option<BoundIdentifier<'a>>, | ||
| temp_binding: Option<BoundIdentifier<'a>>, | ||
| ) -> Self { | ||
| Self { | ||
| name: name_binding, | ||
| temp: temp_binding, | ||
| #[cfg(debug_assertions)] | ||
| currently_transforming_static_property_initializers: false, | ||
| } | ||
| } | ||
|
|
||
| /// Get `SymbolId` of name binding. | ||
| pub fn name_symbol_id(&self) -> Option<SymbolId> { | ||
| self.name.as_ref().map(|binding| binding.symbol_id) | ||
| } | ||
|
|
||
| /// Create a binding for temp var, if there isn't one already. | ||
| pub fn get_or_init_temp_binding(&mut self, ctx: &mut TraverseCtx<'a>) -> &BoundIdentifier<'a> { | ||
| if self.temp.is_none() { | ||
| // This should only be possible if we are currently transforming static prop initializers | ||
| #[cfg(debug_assertions)] | ||
| { | ||
| assert!( | ||
| self.currently_transforming_static_property_initializers, | ||
| "Should be unreachable" | ||
| ); | ||
| } | ||
|
|
||
| self.temp = Some(Self::create_temp_binding(self.name.as_ref(), ctx)); | ||
| } | ||
| self.temp.as_ref().unwrap() | ||
| } | ||
|
|
||
| /// Generate a binding for temp var. | ||
| pub fn create_temp_binding( | ||
| name_binding: Option<&BoundIdentifier<'a>>, | ||
| ctx: &mut TraverseCtx<'a>, | ||
| ) -> BoundIdentifier<'a> { | ||
| // Base temp binding name on class name, or "Class" if no name. | ||
| // TODO(improve-on-babel): If class name var isn't mutated, no need for temp var for | ||
| // class declaration. Can just use class binding. | ||
| let name = name_binding.map_or("Class", |binding| binding.name.as_str()); | ||
| ctx.generate_uid_in_current_scope(name, SymbolFlags::FunctionScopedVariable) | ||
| } | ||
| } |
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