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feat(next-swc): Implement CJS optimizer (vercel#49972)
### What? Implement a CJS optimizer for next-swc ### Why? x-ref: https://vercel.slack.com/archives/C02HY34AKME/p1684341093462309 Assuming most CJS files are transpiled from ESM, we can mimic tree-shaking using an AST transform. ### How? Closes WEB-1072 Fixes vercel#48469 fix NEXT-1156 --------- Co-authored-by: Shu Ding <g@shud.in>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,279 @@ | ||
| use rustc_hash::{FxHashMap, FxHashSet}; | ||
| use serde::Deserialize; | ||
| use turbopack_binding::swc::core::{ | ||
| common::{util::take::Take, SyntaxContext, DUMMY_SP}, | ||
| ecma::{ | ||
| ast::{ | ||
| CallExpr, Callee, Decl, Expr, Id, Ident, Lit, MemberExpr, MemberProp, Module, | ||
| ModuleItem, Pat, Script, Stmt, VarDecl, VarDeclKind, VarDeclarator, | ||
| }, | ||
| atoms::{Atom, JsWord}, | ||
| utils::{prepend_stmts, private_ident, ExprFactory, IdentRenamer}, | ||
| visit::{ | ||
| as_folder, noop_visit_mut_type, noop_visit_type, Fold, Visit, VisitMut, VisitMutWith, | ||
| VisitWith, | ||
| }, | ||
| }, | ||
| }; | ||
|
|
||
| pub fn cjs_optimizer(config: Config, unresolved_ctxt: SyntaxContext) -> impl Fold + VisitMut { | ||
| as_folder(CjsOptimizer { | ||
| data: State::default(), | ||
| packages: config.packages, | ||
| unresolved_ctxt, | ||
| }) | ||
| } | ||
|
|
||
| #[derive(Clone, Debug, Deserialize)] | ||
| pub struct Config { | ||
| pub packages: FxHashMap<String, PackageConfig>, | ||
| } | ||
|
|
||
| #[derive(Clone, Debug, Deserialize)] | ||
| #[serde(rename_all = "camelCase")] | ||
| pub struct PackageConfig { | ||
| pub transforms: FxHashMap<JsWord, JsWord>, | ||
| } | ||
|
|
||
| struct CjsOptimizer { | ||
| data: State, | ||
| packages: FxHashMap<String, PackageConfig>, | ||
| unresolved_ctxt: SyntaxContext, | ||
| } | ||
|
|
||
| #[derive(Debug, Default)] | ||
| struct State { | ||
| /// List of `require` calls **which should be replaced**. | ||
| /// | ||
| /// `(identifier): (module_record)` | ||
| imports: FxHashMap<Id, ImportRecord>, | ||
|
|
||
| /// `(module_specifier, property): (identifier)` | ||
| replaced: FxHashMap<(Atom, JsWord), Id>, | ||
|
|
||
| extra_stmts: Vec<Stmt>, | ||
|
|
||
| rename_map: FxHashMap<Id, Id>, | ||
|
|
||
| /// Ignored identifiers for `obj` of [MemberExpr]. | ||
| ignored: FxHashSet<Id>, | ||
|
|
||
| is_prepass: bool, | ||
| } | ||
|
|
||
| #[derive(Debug)] | ||
| struct ImportRecord { | ||
| module_specifier: Atom, | ||
| } | ||
|
|
||
| impl CjsOptimizer { | ||
| fn should_rewrite(&self, module_specifier: &str) -> Option<&FxHashMap<JsWord, JsWord>> { | ||
| self.packages.get(module_specifier).map(|v| &v.transforms) | ||
| } | ||
| } | ||
|
|
||
| impl VisitMut for CjsOptimizer { | ||
| noop_visit_mut_type!(); | ||
|
|
||
| fn visit_mut_module_items(&mut self, stmts: &mut Vec<ModuleItem>) { | ||
| self.data.is_prepass = true; | ||
| stmts.visit_mut_children_with(self); | ||
| self.data.is_prepass = false; | ||
| stmts.visit_mut_children_with(self); | ||
| } | ||
|
|
||
| fn visit_mut_expr(&mut self, e: &mut Expr) { | ||
| e.visit_mut_children_with(self); | ||
|
|
||
| if let Expr::Member(n) = e { | ||
| if let MemberProp::Ident(prop) = &n.prop { | ||
| if let Expr::Ident(obj) = &*n.obj { | ||
| let key = obj.to_id(); | ||
| if self.data.ignored.contains(&key) { | ||
| return; | ||
| } | ||
|
|
||
| if let Some(record) = self.data.imports.get(&key) { | ||
| let mut replaced = false; | ||
|
|
||
| let new_id = self | ||
| .data | ||
| .replaced | ||
| .entry((record.module_specifier.clone(), prop.sym.clone())) | ||
| .or_insert_with(|| private_ident!(prop.sym.clone()).to_id()) | ||
| .clone(); | ||
|
|
||
| if let Some(map) = self.should_rewrite(&record.module_specifier) { | ||
| if let Some(renamed) = map.get(&prop.sym) { | ||
| replaced = true; | ||
| if !self.data.is_prepass { | ||
| // Transform as `require('foo').bar` | ||
| let var = VarDeclarator { | ||
| span: DUMMY_SP, | ||
| name: Pat::Ident(new_id.clone().into()), | ||
| init: Some(Box::new(Expr::Member(MemberExpr { | ||
| span: DUMMY_SP, | ||
| obj: Box::new(Expr::Call(CallExpr { | ||
| span: DUMMY_SP, | ||
| callee: Ident::new( | ||
| "require".into(), | ||
| DUMMY_SP.with_ctxt(self.unresolved_ctxt), | ||
| ) | ||
| .as_callee(), | ||
| args: vec![Expr::Lit(Lit::Str( | ||
| renamed.clone().into(), | ||
| )) | ||
| .as_arg()], | ||
| type_args: None, | ||
| })), | ||
| prop: MemberProp::Ident(Ident::new( | ||
| prop.sym.clone(), | ||
| DUMMY_SP.with_ctxt(self.unresolved_ctxt), | ||
| )), | ||
| }))), | ||
| definite: false, | ||
| }; | ||
|
|
||
| self.data.extra_stmts.push(Stmt::Decl(Decl::Var(Box::new( | ||
| VarDecl { | ||
| span: DUMMY_SP, | ||
| kind: VarDeclKind::Const, | ||
| declare: false, | ||
| decls: vec![var], | ||
| }, | ||
| )))); | ||
|
|
||
| *e = Expr::Ident(new_id.into()); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| if !replaced { | ||
| self.data.ignored.insert(key); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn visit_mut_module(&mut self, n: &mut Module) { | ||
| n.visit_children_with(&mut Analyzer { | ||
| data: &mut self.data, | ||
| in_member_or_var: false, | ||
| }); | ||
|
|
||
| n.visit_mut_children_with(self); | ||
|
|
||
| prepend_stmts( | ||
| &mut n.body, | ||
| self.data.extra_stmts.drain(..).map(ModuleItem::Stmt), | ||
| ); | ||
|
|
||
| n.visit_mut_children_with(&mut IdentRenamer::new(&self.data.rename_map)); | ||
| } | ||
|
|
||
| fn visit_mut_script(&mut self, n: &mut Script) { | ||
| n.visit_children_with(&mut Analyzer { | ||
| data: &mut self.data, | ||
| in_member_or_var: false, | ||
| }); | ||
|
|
||
| n.visit_mut_children_with(self); | ||
|
|
||
| prepend_stmts(&mut n.body, self.data.extra_stmts.drain(..)); | ||
|
|
||
| n.visit_mut_children_with(&mut IdentRenamer::new(&self.data.rename_map)); | ||
| } | ||
|
|
||
| fn visit_mut_stmt(&mut self, n: &mut Stmt) { | ||
| n.visit_mut_children_with(self); | ||
|
|
||
| if let Stmt::Decl(Decl::Var(v)) = n { | ||
| if v.decls.is_empty() { | ||
| n.take(); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn visit_mut_var_declarator(&mut self, n: &mut VarDeclarator) { | ||
| n.visit_mut_children_with(self); | ||
|
|
||
| // Find `require('foo')` | ||
| if let Some(Expr::Call(CallExpr { | ||
| callee: Callee::Expr(callee), | ||
| args, | ||
| .. | ||
| })) = n.init.as_deref() | ||
| { | ||
| if let Expr::Ident(ident) = &**callee { | ||
| if ident.span.ctxt == self.unresolved_ctxt && ident.sym == *"require" { | ||
| if let Some(arg) = args.get(0) { | ||
| if let Expr::Lit(Lit::Str(v)) = &*arg.expr { | ||
| // TODO: Config | ||
|
|
||
| if let Pat::Ident(name) = &n.name { | ||
| if let Some(..) = self.should_rewrite(&v.value) { | ||
| let key = name.to_id(); | ||
|
|
||
| if !self.data.is_prepass { | ||
| if !self.data.ignored.contains(&key) { | ||
| // Drop variable declarator. | ||
| n.name.take(); | ||
| } | ||
| } else { | ||
| self.data.imports.insert( | ||
| key, | ||
| ImportRecord { | ||
| module_specifier: v.value.clone().into(), | ||
| }, | ||
| ); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn visit_mut_var_declarators(&mut self, n: &mut Vec<VarDeclarator>) { | ||
| n.visit_mut_children_with(self); | ||
|
|
||
| // We make `name` invalid if we should drop it. | ||
| n.retain(|v| !v.name.is_invalid()); | ||
| } | ||
| } | ||
|
|
||
| struct Analyzer<'a> { | ||
| in_member_or_var: bool, | ||
| data: &'a mut State, | ||
| } | ||
|
|
||
| impl Visit for Analyzer<'_> { | ||
| noop_visit_type!(); | ||
|
|
||
| fn visit_var_declarator(&mut self, n: &VarDeclarator) { | ||
| self.in_member_or_var = true; | ||
| n.visit_children_with(self); | ||
| self.in_member_or_var = false; | ||
| } | ||
|
|
||
| fn visit_member_expr(&mut self, e: &MemberExpr) { | ||
| self.in_member_or_var = true; | ||
| e.visit_children_with(self); | ||
| self.in_member_or_var = false; | ||
|
|
||
| if let (Expr::Ident(obj), MemberProp::Computed(..)) = (&*e.obj, &e.prop) { | ||
| self.data.ignored.insert(obj.to_id()); | ||
| } | ||
| } | ||
|
|
||
| fn visit_ident(&mut self, i: &Ident) { | ||
| i.visit_children_with(self); | ||
| if !self.in_member_or_var { | ||
| self.data.ignored.insert(i.to_id()); | ||
| } | ||
| } | ||
| } |
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