perf(transformer/jsx): no string comparisons generating pragma expression

crates/oxc_transformer/src/jsx/jsx_impl.rs

@@ -312,9 +312,20 @@ fn get_import_source(jsx_runtime_importer: &str, react_importer_len: u32) -> Ato
     Atom::from(&jsx_runtime_importer[..react_importer_len as usize])
 }
 
-/// Pragma used in classic mode
-struct Pragma<'a> {
-    ident_parts: Vec<Atom<'a>>,
+/// Pragma used in classic mode.
+///
+/// `Double` is first as it's most common.
+enum Pragma<'a> {
+    /// `React.createElement`
+    Double(Atom<'a>, Atom<'a>),
+    /// `createElement`
+    Single(Atom<'a>),
+    /// `foo.bar.qux`
+    Multiple(Vec<Atom<'a>>),
+    /// `this`, `this.foo`, `this.foo.bar.qux`
+    This(Vec<Atom<'a>>),
+    /// `import.meta`, `import.meta.foo`, `import.meta.foo.bar.qux`
+    ImportMeta(Vec<Atom<'a>>),
 }
 
 impl<'a> Pragma<'a> {
@@ -329,43 +340,64 @@ impl<'a> Pragma<'a> {
     ) -> Self {
         if let Some(pragma) = pragma {
             if pragma.is_empty() {
-                return Self::invalid(default_property_name, ctx);
+                ctx.error(diagnostics::invalid_pragma());
+            } else {
+                return Self::parse_impl(pragma, ast);
             }
-
-            let ident_parts = pragma.split('.').map(|item| ast.atom(item)).collect::<Vec<_>>();
-            Self { ident_parts }
-        } else {
-            Self::default(default_property_name)
         }
-    }
 
-    fn invalid(default_property_name: &'static str, ctx: &TransformCtx<'a>) -> Self {
-        ctx.error(diagnostics::invalid_pragma());
-        Self::default(default_property_name)
+        Self::Double(Atom::from("React"), Atom::from(default_property_name))
     }
 
-    fn default(default_property_name: &'static str) -> Self {
-        Self { ident_parts: vec![Atom::from("React"), Atom::from(default_property_name)] }
+    fn parse_impl(pragma: &str, ast: AstBuilder<'a>) -> Self {
+        let strs_to_atoms = |parts: &[&str]| parts.iter().map(|part| ast.atom(part)).collect();
+
+        let parts = pragma.split('.').collect::<Vec<_>>();
+        match &parts[..] {
+            [] => unreachable!(),
+            ["this", rest @ ..] => Self::This(strs_to_atoms(rest)),
+            ["import", "meta", rest @ ..] => Self::ImportMeta(strs_to_atoms(rest)),
+            [first, second] => Self::Double(ast.atom(first), ast.atom(second)),
+            [only] => Self::Single(ast.atom(only)),
+            parts => Self::Multiple(strs_to_atoms(parts)),
+        }
     }
 
     fn create_expression(&self, ctx: &mut TraverseCtx<'a>) -> Expression<'a> {
-        let (mut expr, parts) = match &self.ident_parts[..] {
-            [] => unreachable!(),
-            [atom, rest @ ..] if atom == "this" => (ctx.ast.expression_this(SPAN), rest),
-            [first, second, rest @ ..] if first == "import" && second == "meta" => (
-                ctx.ast.expression_meta_property(
-                    SPAN,
-                    ctx.ast.identifier_name(SPAN, first),
-                    ctx.ast.identifier_name(SPAN, second),
-                ),
-                rest,
-            ),
-            [first, rest @ ..] => {
+        let (object, parts) = match self {
+            Self::Double(first, second) => {
                 let object = get_read_identifier_reference(SPAN, first.clone(), ctx);
-                let expr = Expression::Identifier(ctx.alloc(object));
-                (expr, rest)
+                return Expression::from(ctx.ast.member_expression_static(
+                    SPAN,
+                    object,
+                    ctx.ast.identifier_name(SPAN, second.clone()),
+                    false,
+                ));
+            }
+            Self::Single(single) => {
+                return get_read_identifier_reference(SPAN, single.clone(), ctx);
+            }
+            Self::Multiple(parts) => {
+                let mut parts = parts.iter();
+                let first = parts.next().unwrap().clone();
+                let object = get_read_identifier_reference(SPAN, first, ctx);
+                (object, parts)
+            }
+            Self::This(parts) => {
+                let object = ctx.ast.expression_this(SPAN);
+                (object, parts.iter())
+            }
+            Self::ImportMeta(parts) => {
+                let object = ctx.ast.expression_meta_property(
+                    SPAN,
+                    ctx.ast.identifier_name(SPAN, Atom::from("import")),
+                    ctx.ast.identifier_name(SPAN, Atom::from("meta")),
+                );
+                (object, parts.iter())
             }
         };
+
+        let mut expr = object;
         for item in parts {
             let name = ctx.ast.identifier_name(SPAN, item.clone());
             expr = ctx.ast.member_expression_static(SPAN, expr, name, false).into();
@@ -1049,10 +1081,11 @@ fn get_read_identifier_reference<'a>(
     span: Span,
     name: Atom<'a>,
     ctx: &mut TraverseCtx<'a>,
-) -> IdentifierReference<'a> {
+) -> Expression<'a> {
     let reference_id =
         ctx.create_reference_in_current_scope(name.to_compact_str(), ReferenceFlags::Read);
-    ctx.ast.identifier_reference_with_reference_id(span, name, reference_id)
+    let ident = ctx.ast.alloc_identifier_reference_with_reference_id(span, name, reference_id);
+    Expression::Identifier(ident)
 }
 
 fn create_static_member_expression<'a>(
@@ -1076,6 +1109,7 @@ mod test {
     use oxc_allocator::Allocator;
     use oxc_ast::ast::Expression;
     use oxc_semantic::{ScopeTree, SymbolTable};
+    use oxc_syntax::{node::NodeId, scope::ScopeFlags};
     use oxc_traverse::ReusableTraverseCtx;
 
     use crate::{TransformCtx, TransformOptions};
@@ -1085,18 +1119,91 @@ mod test {
     macro_rules! setup {
         ($traverse_ctx:ident, $transform_ctx:ident) => {
             let allocator = Allocator::default();
-            let traverse_ctx =
-                ReusableTraverseCtx::new(ScopeTree::default(), SymbolTable::default(), &allocator);
+
+            let mut scopes = ScopeTree::default();
+            scopes.add_scope(None, NodeId::DUMMY, ScopeFlags::Top);
+
+            let traverse_ctx = ReusableTraverseCtx::new(scopes, SymbolTable::default(), &allocator);
             // SAFETY: Macro user only gets a `&mut TraverseCtx`, which cannot be abused
             let mut traverse_ctx = unsafe { traverse_ctx.unwrap() };
             let $traverse_ctx = &mut traverse_ctx;
+
             let $transform_ctx =
                 TransformCtx::new(Path::new("test.jsx"), &TransformOptions::default());
         };
     }
 
     #[test]
-    fn this_expr_pragma() {
+    fn default_pragma() {
+        setup!(traverse_ctx, transform_ctx);
+
+        let pragma = None;
+        let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
+        let expr = pragma.create_expression(traverse_ctx);
+
+        let Expression::StaticMemberExpression(member) = &expr else { panic!() };
+        let Expression::Identifier(object) = &member.object else { panic!() };
+        assert_eq!(object.name, "React");
+        assert_eq!(member.property.name, "createElement");
+    }
+
+    #[test]
+    fn single_part_pragma() {
+        setup!(traverse_ctx, transform_ctx);
+
+        let pragma = Some("single");
+        let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
+        let expr = pragma.create_expression(traverse_ctx);
+
+        let Expression::Identifier(ident) = &expr else { panic!() };
+        assert_eq!(ident.name, "single");
+    }
+
+    #[test]
+    fn two_part_pragma() {
+        setup!(traverse_ctx, transform_ctx);
+
+        let pragma = Some("first.second");
+        let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
+        let expr = pragma.create_expression(traverse_ctx);
+
+        let Expression::StaticMemberExpression(member) = &expr else { panic!() };
+        let Expression::Identifier(object) = &member.object else { panic!() };
+        assert_eq!(object.name, "first");
+        assert_eq!(member.property.name, "second");
+    }
+
+    #[test]
+    fn multi_part_pragma() {
+        setup!(traverse_ctx, transform_ctx);
+
+        let pragma = Some("first.second.third");
+        let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
+        let expr = pragma.create_expression(traverse_ctx);
+
+        let Expression::StaticMemberExpression(outer_member) = &expr else { panic!() };
+        let Expression::StaticMemberExpression(inner_member) = &outer_member.object else {
+            panic!()
+        };
+        let Expression::Identifier(object) = &inner_member.object else { panic!() };
+        assert_eq!(object.name, "first");
+        assert_eq!(inner_member.property.name, "second");
+        assert_eq!(outer_member.property.name, "third");
+    }
+
+    #[test]
+    fn this_pragma() {
+        setup!(traverse_ctx, transform_ctx);
+
+        let pragma = Some("this");
+        let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
+        let expr = pragma.create_expression(traverse_ctx);
+
+        assert!(matches!(&expr, Expression::ThisExpression(_)));
+    }
+
+    #[test]
+    fn this_prop_pragma() {
         setup!(traverse_ctx, transform_ctx);
 
         let pragma = Some("this.a.b");
@@ -1116,6 +1223,19 @@ mod test {
     fn import_meta_pragma() {
         setup!(traverse_ctx, transform_ctx);
 
+        let pragma = Some("import.meta");
+        let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
+        let expr = pragma.create_expression(traverse_ctx);
+
+        let Expression::MetaProperty(meta_prop) = &expr else { panic!() };
+        assert_eq!(&meta_prop.meta.name, "import");
+        assert_eq!(&meta_prop.property.name, "meta");
+    }
+
+    #[test]
+    fn import_meta_prop_pragma() {
+        setup!(traverse_ctx, transform_ctx);
+
         let pragma = Some("import.meta.prop");
         let pragma = Pragma::parse(pragma, "createElement", traverse_ctx.ast, &transform_ctx);
         let expr = pragma.create_expression(traverse_ctx);