feat(transformer): duplicate keys (#1649)

crates/oxc_transformer/src/es2015/duplicate_keys.rs

@@ -0,0 +1,74 @@
+#![allow(clippy::similar_names)]
+
+use std::{collections::HashSet, rc::Rc};
+
+use oxc_ast::{ast::*, AstBuilder};
+use oxc_span::{Atom, SPAN};
+
+use crate::options::{TransformOptions, TransformTarget};
+
+/// ES2015: Duplicate Keys
+///
+/// References:
+/// * <https://babeljs.io/docs/babel-plugin-transform-duplicate-keys>
+/// * <https://github.com/babel/babel/blob/main/packages/babel-plugin-transform-duplicate-keys>
+pub struct DuplicateKeys<'a> {
+    ast: Rc<AstBuilder<'a>>,
+}
+
+impl<'a> DuplicateKeys<'a> {
+    pub fn new(ast: Rc<AstBuilder<'a>>, options: &TransformOptions) -> Option<Self> {
+        (options.target < TransformTarget::ES2015 || options.duplicate_keys).then(|| Self { ast })
+    }
+
+    pub fn transform_object_expression<'b>(&mut self, obj_expr: &'b mut ObjectExpression<'a>) {
+        let mut visited_data: HashSet<Atom> = HashSet::new();
+        let mut visited_getters: HashSet<Atom> = HashSet::new();
+        let mut visited_setters: HashSet<Atom> = HashSet::new();
+
+        for property in obj_expr.properties.iter_mut() {
+            let ObjectPropertyKind::ObjectProperty(obj_property) = property else {
+                continue;
+            };
+
+            if obj_property.computed {
+                continue;
+            }
+
+            if let Some(name) = &obj_property.key.static_name() {
+                let mut is_duplicate = false;
+
+                match obj_property.kind {
+                    PropertyKind::Get => {
+                        if visited_data.contains(name) || visited_getters.contains(name) {
+                            is_duplicate = true;
+                        }
+                        visited_getters.insert(name.clone());
+                    }
+                    PropertyKind::Set => {
+                        if visited_data.contains(name) || visited_setters.contains(name) {
+                            is_duplicate = true;
+                        }
+                        visited_setters.insert(name.clone());
+                    }
+                    PropertyKind::Init => {
+                        if visited_data.contains(name)
+                            || visited_setters.contains(name)
+                            || visited_getters.contains(name)
+                        {
+                            is_duplicate = true;
+                        }
+                        visited_data.insert(name.clone());
+                    }
+                }
+
+                if is_duplicate {
+                    obj_property.computed = true;
+                    let string_literal = StringLiteral::new(SPAN, name.as_str().into());
+                    let expr = self.ast.literal_string_expression(string_literal);
+                    obj_property.key = PropertyKey::Expression(expr);
+                }
+            }
+        }
+    }
+}

crates/oxc_transformer/src/es2015/mod.rs

@@ -1,7 +1,9 @@
+mod duplicate_keys;
 mod function_name;
 mod shorthand_properties;
 mod template_literals;
 
+pub use duplicate_keys::DuplicateKeys;
 pub use function_name::FunctionName;
 pub use shorthand_properties::ShorthandProperties;
 pub use template_literals::TemplateLiterals;

crates/oxc_transformer/src/lib.rs

@@ -65,6 +65,7 @@ pub struct Transformer<'a> {
     es2015_function_name: Option<FunctionName<'a>>,
     es2015_shorthand_properties: Option<ShorthandProperties<'a>>,
     es2015_template_literals: Option<TemplateLiterals<'a>>,
+    es2015_duplicate_keys: Option<DuplicateKeys<'a>>,
     es3_property_literal: Option<PropertyLiteral<'a>>,
 }
 
@@ -101,6 +102,7 @@ impl<'a> Transformer<'a> {
             es2015_function_name: FunctionName::new(Rc::clone(&ast), ctx.clone(), &options),
             es2015_shorthand_properties: ShorthandProperties::new(Rc::clone(&ast), &options),
             es2015_template_literals: TemplateLiterals::new(Rc::clone(&ast), &options),
+            es2015_duplicate_keys: DuplicateKeys::new(Rc::clone(&ast), &options),
             // other
             es3_property_literal: PropertyLiteral::new(Rc::clone(&ast), &options),
             react_jsx: ReactJsx::new(Rc::clone(&ast), ctx.clone(), options)
@@ -189,6 +191,7 @@ impl<'a> VisitMut<'a> for Transformer<'a> {
 
     fn visit_object_expression(&mut self, expr: &mut ObjectExpression<'a>) {
         self.es2015_function_name.as_mut().map(|t| t.transform_object_expression(expr));
+        self.es2015_duplicate_keys.as_mut().map(|t| t.transform_object_expression(expr));
 
         for property in expr.properties.iter_mut() {
             self.visit_object_property_kind(property);

crates/oxc_transformer/src/options.rs

@@ -20,6 +20,7 @@ pub struct TransformOptions {
     // es2016
     pub exponentiation_operator: bool,
     // es2015
+    pub duplicate_keys: bool,
     pub function_name: bool,
     pub shorthand_properties: bool,
     pub sticky_regex: bool,

tasks/transform_conformance/babel.snap.md

@@ -1,4 +1,4 @@
-Passed: 270/1103
+Passed: 277/1111
 
 # All Passed:
 * babel-plugin-transform-numeric-separator
@@ -772,6 +772,9 @@ Passed: 270/1103
 * loose/ignoreToPrimitiveHint/input.js
 * loose/mutableTemplateObject/input.js
 
+# babel-plugin-transform-duplicate-keys (7/8)
+* combination/dupes/input.js
+
 # babel-plugin-transform-typescript (66/158)
 * class/abstract-class-decorated/input.ts
 * class/abstract-class-decorated-method/input.ts

tasks/transform_conformance/src/lib.rs

@@ -78,6 +78,7 @@ const CASES: &[&str] = &[
     "babel-plugin-transform-sticky-regex",
     "babel-plugin-transform-unicode-regex",
     "babel-plugin-transform-template-literals",
+    "babel-plugin-transform-duplicate-keys",
     // ES3
     "babel-plugin-transform-property-literals",
     // TypeScript

tasks/transform_conformance/src/test_case.rs

@@ -111,6 +111,7 @@ pub trait TestCase {
             sticky_regex: options.get_plugin("transform-sticky-regex").is_some(),
             template_literals: options.get_plugin("transform-template-literals").is_some(),
             property_literals: options.get_plugin("transform-property-literals").is_some(),
+            duplicate_keys: options.get_plugin("transform-duplicate-keys").is_some(),
         }
     }