refactor(es/utils): Refine some APIs

crates/swc_bundler/src/bundler/chunk/cjs.rs

@@ -3,7 +3,7 @@ use std::{collections::HashMap, sync::atomic::Ordering};
 use anyhow::Error;
 use swc_common::{collections::AHashMap, Span, SyntaxContext, DUMMY_SP};
 use swc_ecma_ast::*;
-use swc_ecma_utils::{quote_ident, undefined, ExprFactory};
+use swc_ecma_utils::{quote_ident, ExprFactory};
 use swc_ecma_visit::{noop_visit_mut_type, VisitMut, VisitMutWith};
 
 use crate::{
@@ -168,7 +168,7 @@ fn wrap_module(
                 )
                 .make_member(Ident::new("bind".into(), DUMMY_SP))
                 .as_callee(),
-                args: vec![undefined(DUMMY_SP).as_arg(), module_fn.as_arg()],
+                args: vec![Expr::undefined(DUMMY_SP).as_arg(), module_fn.as_arg()],
                 type_args: None,
             }))),
             definite: false,

crates/swc_ecma_ast/src/expr.rs

@@ -18,8 +18,8 @@ use crate::{
         TsAsExpr, TsConstAssertion, TsInstantiation, TsNonNullExpr, TsSatisfiesExpr, TsTypeAnn,
         TsTypeAssertion, TsTypeParamDecl, TsTypeParamInstantiation,
     },
-    ArrayPat, BindingIdent, ComputedPropName, Id, ImportPhase, Invalid, KeyValueProp, ObjectPat,
-    PropName, Str,
+    ArrayPat, BindingIdent, ComputedPropName, Id, ImportPhase, Invalid, KeyValueProp, Number,
+    ObjectPat, PropName, Str,
 };
 
 #[ast_node(no_clone)]
@@ -171,6 +171,22 @@ bridge_from!(Box<Expr>, Box<JSXElement>, JSXElement);
 // assert_eq_size!(Expr, [u8; 80]);
 
 impl Expr {
+    /// Creates `void 0`.
+    #[inline]
+    pub fn undefined(span: Span) -> Box<Expr> {
+        UnaryExpr {
+            span,
+            op: op!("void"),
+            arg: Lit::Num(Number {
+                span,
+                value: 0.0,
+                raw: None,
+            })
+            .into(),
+        }
+        .into()
+    }
+
     pub fn leftmost(&self) -> Option<&Ident> {
         match self {
             Expr::Ident(i) => Some(i),

crates/swc_ecma_ast/src/ident.rs

@@ -7,7 +7,7 @@ use phf::phf_set;
 use scoped_tls::scoped_thread_local;
 use swc_atoms::{js_word, Atom};
 use swc_common::{
-    ast_node, util::take::Take, BytePos, EqIgnoreSpan, Span, Spanned, SyntaxContext, DUMMY_SP,
+    ast_node, util::take::Take, BytePos, EqIgnoreSpan, Mark, Span, Spanned, SyntaxContext, DUMMY_SP,
 };
 
 use crate::{typescript::TsTypeAnn, Expr};
@@ -307,6 +307,19 @@ impl Ident {
         Err(buf)
     }
 
+    /// Create a new identifier with the given prefix.
+    pub fn with_prefix(&self, prefix: &str) -> Ident {
+        Ident::new(format!("{}{}", prefix, self.sym).into(), self.span)
+    }
+
+    /// Create a private identifier that is unique in the file, but with the
+    /// same symbol.
+    pub fn into_private(self) -> Ident {
+        let span = self.span.apply_mark(Mark::new());
+
+        Self::new(self.sym, span)
+    }
+
     #[inline]
     pub fn is_dummy(&self) -> bool {
         self.sym == js_word!("") && self.span.is_dummy()
@@ -446,7 +459,7 @@ static RESERVED_IN_ES3: phf::Set<&str> = phf_set!(
     "volatile",
 );
 
-pub trait IdentExt: AsRef<str> {
+pub trait EsReserved: AsRef<str> {
     fn is_reserved(&self) -> bool {
         RESERVED.contains(self.as_ref())
     }
@@ -474,7 +487,7 @@ pub trait IdentExt: AsRef<str> {
     }
 }
 
-impl IdentExt for Atom {}
-impl IdentExt for Ident {}
-impl IdentExt for &'_ str {}
-impl IdentExt for String {}
+impl EsReserved for Atom {}
+impl EsReserved for Ident {}
+impl EsReserved for &'_ str {}
+impl EsReserved for String {}

crates/swc_ecma_ast/src/lib.rs

@@ -21,7 +21,7 @@ pub use self::{
     decl::{ClassDecl, Decl, FnDecl, UsingDecl, VarDecl, VarDeclKind, VarDeclarator},
     expr::*,
     function::{Function, Param, ParamOrTsParamProp},
-    ident::{BindingIdent, Id, Ident, IdentExt, PrivateName},
+    ident::{BindingIdent, EsReserved, Id, Ident, PrivateName},
     jsx::{
         JSXAttr, JSXAttrName, JSXAttrOrSpread, JSXAttrValue, JSXClosingElement, JSXClosingFragment,
         JSXElement, JSXElementChild, JSXElementName, JSXEmptyExpr, JSXExpr, JSXExprContainer,

crates/swc_ecma_compat_es2015/src/block_scoping/mod.rs

@@ -13,7 +13,7 @@ use swc_ecma_ast::*;
 use swc_ecma_transforms_base::helper;
 use swc_ecma_utils::{
     find_pat_ids, function::FnEnvHoister, prepend_stmt, private_ident, quote_ident, quote_str,
-    undefined, ExprFactory, StmtLike,
+    ExprFactory, StmtLike,
 };
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, visit_mut_obj_and_computed, Fold, Visit,
@@ -596,7 +596,7 @@ impl VisitMut for BlockScoping {
             if self.var_decl_kind == VarDeclKind::Var {
                 var.init = None
             } else {
-                var.init = Some(undefined(var.span()))
+                var.init = Some(Expr::undefined(var.span()))
             }
         }
     }
@@ -819,7 +819,7 @@ impl VisitMut for FlowHelper<'_> {
                                 Box::new(Expr::Unary(UnaryExpr {
                                     span: DUMMY_SP,
                                     op: op!("void"),
-                                    arg: undefined(DUMMY_SP),
+                                    arg: Expr::undefined(DUMMY_SP),
                                 }))
                             }),
                         })))],
@@ -869,7 +869,7 @@ struct MutationHandler<'a> {
 impl MutationHandler<'_> {
     fn make_reassignment(&self, orig: Option<Box<Expr>>) -> Expr {
         if self.map.is_empty() {
-            return *orig.unwrap_or_else(|| undefined(DUMMY_SP));
+            return *orig.unwrap_or_else(|| Expr::undefined(DUMMY_SP));
         }
 
         let mut exprs = Vec::with_capacity(self.map.len() + 1);
@@ -885,7 +885,7 @@ impl MutationHandler<'_> {
                 ))),
             })));
         }
-        exprs.push(orig.unwrap_or_else(|| undefined(DUMMY_SP)));
+        exprs.push(orig.unwrap_or_else(|| Expr::undefined(DUMMY_SP)));
 
         Expr::Seq(SeqExpr {
             span: DUMMY_SP,

crates/swc_ecma_compat_es2015/src/classes/mod.rs

@@ -12,7 +12,7 @@ use swc_ecma_transforms_macros::fast_path;
 use swc_ecma_utils::{
     alias_if_required, contains_this_expr, default_constructor, is_valid_ident,
     is_valid_prop_ident, prepend_stmt, private_ident, prop_name_to_expr, quote_expr, quote_ident,
-    quote_str, replace_ident, ExprFactory, IdentExt, ModuleItemLike, StmtLike,
+    quote_str, replace_ident, ExprFactory, ModuleItemLike, StmtLike,
 };
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Fold, Visit, VisitMut, VisitMutWith, VisitWith,
@@ -264,7 +264,7 @@ where
         } = d
         {
             if let Expr::Class(c @ ClassExpr { ident: None, .. }) = &mut **init {
-                c.ident = Some(i.id.clone().private())
+                c.ident = Some(i.id.clone().into_private())
             }
         }
 
@@ -275,7 +275,7 @@ where
     fn visit_mut_assign_pat_prop(&mut self, n: &mut AssignPatProp) {
         if let Some(value) = &mut n.value {
             if let Expr::Class(c @ ClassExpr { ident: None, .. }) = &mut **value {
-                c.ident = Some((*n.key).clone().private());
+                c.ident = Some((*n.key).clone().into_private());
             }
         }
 
@@ -290,7 +290,7 @@ where
             Expr::Class(c @ ClassExpr { ident: None, .. }),
         ) = (&*n.left, &mut *n.right)
         {
-            c.ident = Some(id.clone().private())
+            c.ident = Some(id.clone().into_private())
         }
 
         n.visit_mut_children_with(self);
@@ -305,7 +305,7 @@ where
         if let Expr::Class(c @ ClassExpr { ident: None, .. }) = &mut *n.value {
             match &n.key {
                 PropName::Ident(ident) => {
-                    c.ident = Some(ident.clone().private());
+                    c.ident = Some(ident.clone().into_private());
                 }
                 PropName::Str(Str { value, span, .. }) => {
                     if is_valid_prop_ident(value) {
@@ -336,7 +336,7 @@ where
         {
             if let Expr::Class(c @ ClassExpr { ident: None, .. }) = &mut **right {
                 if let AssignTarget::Simple(SimpleAssignTarget::Ident(ident)) = left {
-                    c.ident = Some((**ident).clone().private())
+                    c.ident = Some((**ident).clone().into_private())
                 }
             }
         }

crates/swc_ecma_compat_es2015/src/destructuring.rs

@@ -8,7 +8,7 @@ use swc_ecma_transforms_base::{helper, helper_expr, perf::Check};
 use swc_ecma_transforms_macros::fast_path;
 use swc_ecma_utils::{
     alias_ident_for, alias_if_required, has_rest_pat, is_literal, member_expr, private_ident,
-    prop_name_to_expr, quote_ident, undefined, ExprFactory, StmtLike,
+    prop_name_to_expr, quote_ident, ExprFactory, StmtLike,
 };
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Fold, Visit, VisitMut, VisitMutWith, VisitWith,
@@ -682,7 +682,7 @@ impl VisitMut for AssignFolder {
                                                 debug_assert_eq!(e.spread, None);
                                                 e.expr
                                             })
-                                            .unwrap_or_else(|| undefined(p.span()));
+                                            .unwrap_or_else(|| Expr::undefined(p.span()));
 
                                         let p = p.take();
                                         let mut expr = if let Pat::Assign(pat) = p {
@@ -1002,7 +1002,7 @@ impl VisitMut for AssignFolder {
         if var_decl.kind == VarDeclKind::Const {
             var_decl.decls.iter_mut().for_each(|v| {
                 if v.init.is_none() {
-                    v.init = Some(undefined(DUMMY_SP));
+                    v.init = Some(Expr::undefined(DUMMY_SP));
                 }
             })
         }

crates/swc_ecma_compat_es2015/src/generator.rs

@@ -14,8 +14,7 @@ use swc_common::{
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::helper;
 use swc_ecma_utils::{
-    function::FnEnvHoister, private_ident, prop_name_to_expr_value, quote_ident, undefined,
-    ExprFactory,
+    function::FnEnvHoister, private_ident, prop_name_to_expr_value, quote_ident, ExprFactory,
 };
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Fold, Visit, VisitMut, VisitMutWith, VisitWith,
@@ -812,7 +811,7 @@ impl VisitMut for Generator {
                     &mut args,
                     Some(ExprOrSpread {
                         spread: None,
-                        expr: undefined(DUMMY_SP),
+                        expr: Expr::undefined(DUMMY_SP),
                     }),
                     None,
                 ))
@@ -3463,7 +3462,7 @@ impl Generator {
                 if is_new_call {
                     callee
                 } else {
-                    undefined(DUMMY_SP)
+                    Expr::undefined(DUMMY_SP)
                 },
             ),
 
@@ -3481,7 +3480,7 @@ impl Generator {
 
             _ => {
                 if !is_new_call {
-                    (callee, undefined(DUMMY_SP))
+                    (callee, Expr::undefined(DUMMY_SP))
                 } else {
                     let this_arg = self.create_temp_variable();
                     let target = callee.make_assign_to(op!("="), this_arg.clone().into());

crates/swc_ecma_compat_es2015/src/new_target.rs

@@ -3,7 +3,7 @@ use std::{borrow::Cow, mem};
 use swc_common::{pass::CompilerPass, DUMMY_SP};
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::perf::{should_work, Check};
-use swc_ecma_utils::{private_ident, quote_ident, undefined, ExprFactory};
+use swc_ecma_utils::{private_ident, quote_ident, ExprFactory};
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Fold, Visit, VisitMut, VisitMutWith,
 };
@@ -68,7 +68,7 @@ impl VisitMut for NewTarget {
             };
             match &self.ctx {
                 Ctx::Constructor => *e = this_ctor(*span),
-                Ctx::Method => *e = *undefined(DUMMY_SP),
+                Ctx::Method => *e = *Expr::undefined(DUMMY_SP),
                 Ctx::Function(i) => {
                     *e = Expr::Cond(CondExpr {
                         span: *span,
@@ -81,7 +81,7 @@ impl VisitMut for NewTarget {
                         })),
                         cons: Box::new(this_ctor(DUMMY_SP)),
                         // void 0
-                        alt: undefined(DUMMY_SP),
+                        alt: Expr::undefined(DUMMY_SP),
                     })
                 }
             }

crates/swc_ecma_compat_es2015/src/object_super.rs

@@ -5,7 +5,6 @@ use swc_ecma_ast::*;
 use swc_ecma_transforms_base::helper;
 use swc_ecma_utils::{
     alias_ident_for, is_rest_arguments, prepend_stmt, private_ident, quote_ident, ExprFactory,
-    IdentExt,
 };
 use swc_ecma_visit::{as_folder, noop_visit_mut_type, Fold, VisitMut, VisitMutWith};
 use swc_trace_macro::swc_trace;
@@ -397,7 +396,7 @@ impl SuperReplacer {
                     self.get_proto(),
                     super_token,
                     if computed {
-                        let ref_ident = alias_ident_for(&rhs, "_ref").private();
+                        let ref_ident = alias_ident_for(&rhs, "_ref").into_private();
                         self.vars.push(ref_ident.clone());
                         *prop = Expr::Assign(AssignExpr {
                             span: DUMMY_SP,
@@ -427,7 +426,7 @@ impl SuperReplacer {
                             .as_arg(),
                         )
                     } else {
-                        let update_ident = alias_ident_for(&rhs, "_super").private();
+                        let update_ident = alias_ident_for(&rhs, "_super").into_private();
                         self.vars.push(update_ident.clone());
                         Expr::Seq(SeqExpr {
                             span: DUMMY_SP,

crates/swc_ecma_compat_es2015/src/parameters.rs

@@ -8,7 +8,7 @@ use swc_ecma_ast::*;
 // use swc_ecma_transforms_macros::parallel;
 use swc_ecma_utils::{
     function::{init_this, FnEnvHoister},
-    member_expr, prepend_stmt, prepend_stmts, private_ident, quote_ident, undefined, ExprFactory,
+    member_expr, prepend_stmt, prepend_stmts, private_ident, quote_ident, ExprFactory,
 };
 use swc_ecma_visit::{as_folder, noop_visit_mut_type, Fold, VisitMut, VisitMutWith};
 use swc_trace_macro::swc_trace;
@@ -148,7 +148,7 @@ impl Params {
                                     right: Box::new(Expr::Bin(BinExpr {
                                         left: make_arg_nth(i).into(),
                                         op: op!("!=="),
-                                        right: undefined(DUMMY_SP),
+                                        right: Expr::undefined(DUMMY_SP),
                                         span: DUMMY_SP,
                                     })),
                                     span,
@@ -170,7 +170,7 @@ impl Params {
                                 span: DUMMY_SP,
                                 left: Box::new(Expr::Ident(ident.id.clone())),
                                 op: op!("==="),
-                                right: undefined(DUMMY_SP),
+                                right: Expr::undefined(DUMMY_SP),
                             })),
                             cons: Box::new(Stmt::Expr(ExprStmt {
                                 span,
@@ -203,7 +203,7 @@ impl Params {
                                             span: DUMMY_SP,
                                             left: Box::new(Expr::Ident(binding.clone())),
                                             op: op!("==="),
-                                            right: undefined(DUMMY_SP),
+                                            right: Expr::undefined(DUMMY_SP),
                                         })),
                                         cons: right,
                                         alt: Box::new(Expr::Ident(binding)),
@@ -786,7 +786,7 @@ fn check_arg_len_or_undef(n: usize) -> Expr {
     Expr::Cond(CondExpr {
         test: Box::new(check_arg_len(n)),
         cons: make_arg_nth(n).into(),
-        alt: undefined(DUMMY_SP),
+        alt: Expr::undefined(DUMMY_SP),
         span: DUMMY_SP,
     })
 }

crates/swc_ecma_compat_es2015/src/spread.rs

@@ -6,7 +6,7 @@ use swc_ecma_ast::*;
 use swc_ecma_transforms_base::{ext::ExprRefExt, helper, perf::Check};
 use swc_ecma_transforms_macros::fast_path;
 use swc_ecma_utils::{
-    alias_ident_for, member_expr, prepend_stmt, quote_ident, undefined, ExprFactory, StmtLike,
+    alias_ident_for, member_expr, prepend_stmt, quote_ident, ExprFactory, StmtLike,
 };
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Fold, Visit, VisitMut, VisitMutWith, VisitWith,
@@ -95,7 +95,7 @@ impl VisitMut for Spread {
                         (Box::new(Expr::Ident(obj.as_ident().unwrap().clone())), None)
                     }
 
-                    Expr::Ident(Ident { span, .. }) => (undefined(*span), None),
+                    Expr::Ident(Ident { span, .. }) => (Expr::undefined(*span), None),
 
                     Expr::Member(MemberExpr { span, obj, prop }) => {
                         let ident = alias_ident_for(obj, "_instance");