From 4b5322693f7a807c200e9047c601ca8284201bf6 Mon Sep 17 00:00:00 2001
From: Cameron McHenry <camchenry@users.noreply.github.com>
Date: Sat, 21 Sep 2024 17:02:17 -0400
Subject: [PATCH] Remove character class checker

---
 .../src/rules/eslint/no_regex_spaces.rs       | 36 ++++++++-----------
 1 file changed, 15 insertions(+), 21 deletions(-)

diff --git a/crates/oxc_linter/src/rules/eslint/no_regex_spaces.rs b/crates/oxc_linter/src/rules/eslint/no_regex_spaces.rs
index e817f7c3c3c5a..b5b32548478ba 100644
--- a/crates/oxc_linter/src/rules/eslint/no_regex_spaces.rs
+++ b/crates/oxc_linter/src/rules/eslint/no_regex_spaces.rs
@@ -1,3 +1,5 @@
+use aho_corasick::AhoCorasick;
+use lazy_static::lazy_static;
 use oxc_allocator::{Allocator, Vec};
 use oxc_ast::{
     ast::{Argument, CallExpression, NewExpression, RegExpLiteral},
@@ -45,6 +47,11 @@ declare_oxc_lint!(
     pending // TODO: This is somewhat autofixable, but the fixer does not exist yet.
 );
 
+lazy_static! {
+    static ref DOUBLE_SPACE: AhoCorasick =
+        AhoCorasick::new(["  "]).expect("no-regex-spaces: Unable to build AhoCorasick");
+}
+
 impl Rule for NoRegexSpaces {
     fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
         match node.kind() {
@@ -75,7 +82,7 @@ impl NoRegexSpaces {
     fn find_literal_to_report(literal: &RegExpLiteral, ctx: &LintContext) -> Option<Span> {
         let pattern_text = literal.regex.pattern.source_text(ctx.source_text());
         let pattern_text = pattern_text.as_ref();
-        if Self::has_exempted_char_class(pattern_text) {
+        if !Self::has_double_space(pattern_text) {
             return None;
         }
 
@@ -93,8 +100,8 @@ impl NoRegexSpaces {
         let Some(Argument::StringLiteral(pattern)) = args.first() else {
             return None;
         };
-        if Self::has_exempted_char_class(&pattern.value) {
-            return None; // skip spaces inside char class, e.g. RegExp('[  ]')
+        if !Self::has_double_space(&pattern.value) {
+            return None;
         }
 
         let alloc = Allocator::default();
@@ -121,7 +128,7 @@ impl NoRegexSpaces {
                 in_quantifier = false;
                 return;
             }
-            if ch.value != b' ' as u32 {
+            if ch.value != u32::from(b' ') {
                 return;
             }
             if let Some(ref mut space_span) = last_space_span {
@@ -154,23 +161,10 @@ impl NoRegexSpaces {
         expr.callee.is_specific_id("RegExp") && expr.arguments.len() > 0
     }
 
-    /// Whether the input has a character class but no consecutive spaces
-    /// outside the character class.
-    fn has_exempted_char_class(input: &str) -> bool {
-        let mut inside_class = false;
-
-        for (i, c) in input.chars().enumerate() {
-            match c {
-                '[' => inside_class = true,
-                ']' => inside_class = false,
-                ' ' if input.chars().nth(i + 1) == Some(' ') && !inside_class => {
-                    return false;
-                }
-                _ => {}
-            }
-        }
-
-        true
+    // For skipping if there aren't any consecutive spaces in the source, to avoid reporting cases
+    // where the space is explicitly escaped, like: `RegExp(' \ ')``.
+    fn has_double_space(input: &str) -> bool {
+        DOUBLE_SPACE.is_match(input)
     }
 }