perf(es/parser): Remove redundant is_ascii calls (#10334)

Author: bvanjoi

.changeset/twenty-experts-travel.md

@@ -0,0 +1,7 @@
+---
+swc_ecma_ast: patch
+swc_ecma_parser: patch
+swc_core: patch
+---
+
+perf(es/parser): remove redunant is_ascii

crates/swc_ecma_ast/src/ident.rs

@@ -261,9 +261,9 @@ impl Ident {
         (self.sym.clone(), self.ctxt)
     }
 
-    /// Returns true if `c` is a valid character for an identifier start.
     #[inline]
-    pub fn is_valid_start(c: char) -> bool {
+    pub fn is_valid_ascii_start(c: u8) -> bool {
+        debug_assert!(c.is_ascii());
         // This contains `$` (36) and `_` (95)
         const ASCII_START: Align64<[bool; 128]> = Align64([
             F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F,
@@ -272,18 +272,22 @@ impl Ident {
             T, T, T, T, F, F, F, F, T, F, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T,
             T, T, T, T, T, T, T, F, F, F, F, F,
         ]);
+        ASCII_START.0[c as usize]
+    }
 
+    /// Returns true if `c` is a valid character for an identifier start.
+    #[inline]
+    pub fn is_valid_start(c: char) -> bool {
         if c.is_ascii() {
-            return ASCII_START.0[c as usize];
+            Self::is_valid_ascii_start(c as u8)
+        } else {
+            unicode_id_start::is_id_start_unicode(c)
         }
-
-        unicode_id_start::is_id_start_unicode(c)
     }
 
-    /// Returns true if `c` is a valid character for an identifier part after
-    /// start.
     #[inline]
-    pub fn is_valid_continue(c: char) -> bool {
+    pub fn is_valid_ascii_continue(c: u8) -> bool {
+        debug_assert!(c.is_ascii());
         // This contains `$` (36)
         const ASCII_CONTINUE: Align64<[bool; 128]> = Align64([
             F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F, F,
@@ -292,12 +296,18 @@ impl Ident {
             T, T, T, T, F, F, F, F, T, F, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T, T,
             T, T, T, T, T, T, T, F, F, F, F, F,
         ]);
+        ASCII_CONTINUE.0[c as usize]
+    }
 
+    /// Returns true if `c` is a valid character for an identifier part after
+    /// start.
+    #[inline]
+    pub fn is_valid_continue(c: char) -> bool {
         if c.is_ascii() {
-            return ASCII_CONTINUE.0[c as usize];
+            Self::is_valid_ascii_continue(c as u8)
+        } else {
+            unicode_id_start::is_id_continue_unicode(c)
         }
-
-        unicode_id_start::is_id_continue_unicode(c)
     }
 
     /// Alternative for `toIdentifier` of babel.

crates/swc_ecma_parser/src/lexer/mod.rs

@@ -803,10 +803,10 @@ impl Lexer<'_> {
                         can_be_keyword = false;
                     }
 
-                    if Ident::is_valid_continue(c as _) {
+                    if Ident::is_valid_ascii_continue(c) {
                         l.bump();
                         continue;
-                    } else if first && Ident::is_valid_start(c as _) {
+                    } else if first && Ident::is_valid_ascii_start(c) {
                         l.bump();
                         first = false;
                         continue;
@@ -862,9 +862,7 @@ impl Lexer<'_> {
                     // ASCII but not a valid identifier
 
                     break;
-                }
-
-                if let Some(c) = l.input.cur() {
+                } else if let Some(c) = l.input.cur() {
                     if Ident::is_valid_continue(c) {
                         l.bump();
                         continue;