fix RegExpUtils.isRegexPattern(). AG-35542

Squashed commit of the following: commit b79063f Author: Slava Leleka <[email protected]> Date: Thu Sep 19 18:05:48 2024 +0300 add more tests commit b1cddad Author: Slava Leleka <[email protected]> Date: Thu Sep 19 18:02:24 2024 +0300 fix RegExpUtils.isRegexPattern() if a regexp contains a slash inside the pattern
AdguardTeam · Sep 19, 2024 · 13862c2 · 13862c2
1 parent aa68ebb
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diff --git a/packages/agtree/CHANGELOG.md b/packages/agtree/CHANGELOG.md
@@ -8,6 +8,14 @@ The format is based on [Keep a Changelog][keepachangelog], and this project adhe
 [keepachangelog]: https://keepachangelog.com/en/1.0.0/
 [semver]: https://semver.org/spec/v2.0.0.html
 
+## [2.1.2] - 2024-09-19
+
+### Fixed
+
+- `RegExpUtils.isRegexPattern()` if a regexp contains a slash inside the pattern.
+
+[2.1.2]: https://github.com/AdguardTeam/tsurlfilter/releases/tag/agtree-v2.1.2
+
 ## [2.1.1] - 2024-09-19
 
 ### Fixed

diff --git a/packages/agtree/package.json b/packages/agtree/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@adguard/agtree",
-    "version": "2.1.1",
+    "version": "2.1.2",
     "description": "Tool set for working with adblock filter lists",
     "keywords": [
         "adblock",

diff --git a/packages/agtree/src/utils/regexp.ts b/packages/agtree/src/utils/regexp.ts
@@ -21,7 +21,6 @@ import {
     REGEX_MARKER,
     SLASH,
 } from './constants';
-import { StringUtils } from './string';
 
 // Special RegExp constants
 export const REGEX_START = CARET; // '^'
@@ -70,22 +69,23 @@ export const SPECIAL_REGEX_SYMBOLS = new Set([
  */
 export class RegExpUtils {
     /**
-     * Checks whether a string is a RegExp pattern.
+     * Checks whether a string possibly is a RegExp pattern.
      * Flags are not supported.
      *
+     * Note: it does not perform a full validation of the pattern,
+     * it just checks if the string starts and ends with a slash.
+     *
      * @param pattern - Pattern to check
      * @returns `true` if the string is a RegExp pattern, `false` otherwise
      */
     public static isRegexPattern(pattern: string): boolean {
         const trimmedPattern = pattern.trim();
 
         // Avoid false positives
-        if (trimmedPattern.length > REGEX_MARKER.length * 2 && trimmedPattern.startsWith(REGEX_MARKER)) {
-            const last = StringUtils.findNextUnescapedCharacter(trimmedPattern, REGEX_MARKER, REGEX_MARKER.length);
-            return last === trimmedPattern.length - 1;
-        }
-
-        return false;
+        return trimmedPattern.length > REGEX_MARKER.length * 2
+            && trimmedPattern.startsWith(REGEX_MARKER)
+            && trimmedPattern.endsWith(REGEX_MARKER)
+            && trimmedPattern[REGEX_MARKER.length - 2] !== ESCAPE_CHARACTER;
     }
 
     /**

diff --git a/packages/agtree/test/utils/regexp.test.ts b/packages/agtree/test/utils/regexp.test.ts
@@ -47,6 +47,18 @@ describe('RegExpUtils', () => {
                 actual: '/^regex$/',
                 expected: true,
             },
+            {
+                actual: '/ex[[ampl[[e.com///.*/banner/',
+                expected: true,
+            },
+            {
+                actual: String.raw`/^htt[[[ps?:\/\/.*(example1|example2)\.(com|org)\//`,
+                expected: true,
+            },
+            {
+                actual: String.raw`/\.example\.com/.*[a-zA-Z0-9]({4}/`,
+                expected: true,
+            },
         ])('isRegexPattern should return \'$expected\' for \'$actual\'', ({ actual, expected }) => {
             expect(RegExpUtils.isRegexPattern(actual)).toBe(expected);
         });