From ef5418a917ffecdb6109e198f26bcd27c89c19a0 Mon Sep 17 00:00:00 2001
From: overlookmotel <557937+overlookmotel@users.noreply.github.com>
Date: Wed, 31 Jul 2024 03:32:54 +0000
Subject: [PATCH] refactor(parser): convert `Lexer::read_left_angle` to a
 single match (#4573)

`Lexer::read_left_angle` was a series of disparate `next_ascii_byte_eq` and `peek_byte` calls. Convert it to a single match on `peek_byte`. This I think will remove a couple of bounds checks.
---
 crates/oxc_parser/src/lexer/punctuation.rs | 31 +++++++++++-----------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/crates/oxc_parser/src/lexer/punctuation.rs b/crates/oxc_parser/src/lexer/punctuation.rs
index f49364c80..cc392e9a2 100644
--- a/crates/oxc_parser/src/lexer/punctuation.rs
+++ b/crates/oxc_parser/src/lexer/punctuation.rs
@@ -16,22 +16,23 @@ impl<'a> Lexer<'a> {
 
     /// returns None for `SingleLineHTMLOpenComment` `<!--` in script mode
     pub(super) fn read_left_angle(&mut self) -> Option<Kind> {
-        if self.next_ascii_byte_eq(b'<') {
-            if self.next_ascii_byte_eq(b'=') {
-                Some(Kind::ShiftLeftEq)
-            } else {
-                Some(Kind::ShiftLeft)
+        match self.peek_byte() {
+            Some(b'<') => {
+                self.consume_char();
+                if self.next_ascii_byte_eq(b'=') {
+                    Some(Kind::ShiftLeftEq)
+                } else {
+                    Some(Kind::ShiftLeft)
+                }
             }
-        } else if self.next_ascii_byte_eq(b'=') {
-            Some(Kind::LtEq)
-        } else if self.peek_byte() == Some(b'!')
-            // SingleLineHTMLOpenComment `<!--` in script mode
-            && self.source_type.is_script()
-            && self.remaining().starts_with("!--")
-        {
-            None
-        } else {
-            Some(Kind::LAngle)
+            Some(b'=') => {
+                self.consume_char();
+                Some(Kind::LtEq)
+            }
+            Some(b'!') if self.source_type.is_script() && self.remaining().starts_with("!--") => {
+                None
+            }
+            _ => Some(Kind::LAngle),
         }
     }