AG-36228 Optimized performance of parsing uBlock filter parameters

Merge in ADGUARD-FILTERS/tsurlfilter from fix/AG-36228 to master

Squashed commit of the following:

commit 23c9ac9
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Fri Oct 18 13:49:12 2024 +0300

    Revert "fix names"

    This reverts commit ec3e324.

commit ec3e324
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Fri Oct 18 13:48:00 2024 +0300

    fix names

commit 11898ac
Author: Kurbanali Ruslan <r.kurbanali@adguard.com>
Date:   Thu Oct 17 14:08:46 2024 +0500

    added changelog

commit dfb2481
Author: Kurbanali Ruslan <r.kurbanali@adguard.com>
Date:   Thu Oct 17 13:42:54 2024 +0500

    added test cases

commit ef598e0
Author: Kurbanali Ruslan <r.kurbanali@adguard.com>
Date:   Thu Oct 17 13:42:48 2024 +0500

    fixed slow code

commit d041197
Author: Kurbanali Ruslan <r.kurbanali@adguard.com>
Date:   Thu Oct 17 13:42:29 2024 +0500

    added params to string utils

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
 
+## Unreleased
+
+### Fixed
+
+- Optimized performance of parsing uBlock filter parameters [AdguardBrowserExtension#2962].
+
+[AdguardBrowserExtension#2962]: https://github.com/AdguardTeam/AdguardBrowserExtension/issues/2962
+
 ## [2.1.2] - 2024-09-19
 
 ### Fixed

packages/agtree/src/parser/misc/ubo-parameter-list.ts

@@ -1,7 +1,7 @@
 /* eslint-disable no-param-reassign */
 import { StringUtils } from '../../utils/string';
 import { type ParameterList } from '../common';
-import { COMMA } from '../../utils/constants';
+import { COMMA, ESCAPE_CHARACTER } from '../../utils/constants';
 import { defaultParserOptions } from '../options';
 import { ValueParser } from './value';
 import { AdblockSyntaxError } from '../../errors/adblock-syntax-error';
@@ -61,13 +61,6 @@ export class UboParameterListParser extends ParameterListParser {
                     const nextSeparatorIndex = StringUtils.skipWS(raw, possibleClosingQuoteIndex + 1);
 
                     if (nextSeparatorIndex === length) {
-                        if (requireQuotes) {
-                            throw new AdblockSyntaxError(
-                                'Expected separator, got end of string',
-                                baseOffset + nextSeparatorIndex,
-                                baseOffset + length,
-                            );
-                        }
                         // If the separator is not found, the param end is the end of the string
                         paramEnd = StringUtils.skipWSBack(raw, length - 1) + 1;
                         offset = length;
@@ -83,13 +76,51 @@ export class UboParameterListParser extends ParameterListParser {
                                 baseOffset + length,
                             );
                         }
-                        // Param end should be the last separator before the quote
-                        offset = StringUtils.findNextUnescapedCharacterBackwards(
+
+                        /**
+                         * At that point found `possibleClosingQuoteIndex` is wrong
+                         * | is `offset`
+                         * ~ is `possibleClosingQuoteIndex`
+                         * ^ is `nextSeparatorIndex`
+                         *
+                         * Example 1: "abc, ').cba='1'"
+                         *                  |      ~^
+                         * Example 2: "abc, ').cba, '1'"
+                         *                  |       ~^
+                         * Example 3: "abc, ').cba='1', cba"
+                         *                  |      ~^
+                         *
+                         * Search for separator before `possibleClosingQuoteIndex`
+                         */
+
+                        const separatorIndexBeforeQuote = StringUtils.findNextUnescapedCharacterBackwards(
                             raw,
                             separator,
                             possibleClosingQuoteIndex,
-                        ) + 1;
-                        paramEnd = StringUtils.skipWSBack(raw, offset - 2) + 1;
+                            ESCAPE_CHARACTER,
+                            offset + 1,
+                        );
+                        if (separatorIndexBeforeQuote !== -1) {
+                            // Found separator before (Example 2)
+                            paramEnd = StringUtils.skipWSBack(raw, separatorIndexBeforeQuote - 1) + 1;
+                            offset = separatorIndexBeforeQuote + 1;
+                        } else {
+                            // Didn't found separator before, search after
+                            const separatorIndexAfterQuote = StringUtils.findNextUnescapedCharacter(
+                                raw,
+                                separator,
+                                possibleClosingQuoteIndex,
+                            );
+                            if (separatorIndexAfterQuote !== -1) {
+                                // We found separator after (Example 3)
+                                paramEnd = StringUtils.skipWSBack(raw, separatorIndexAfterQuote - 1) + 1;
+                                offset = separatorIndexAfterQuote + 1;
+                            } else {
+                                // If the separator is not found, the param end is the end of the string (Example 1)
+                                paramEnd = StringUtils.skipWSBack(raw, length - 1) + 1;
+                                offset = length;
+                            }
+                        }
                     }
                 } else {
                     if (requireQuotes) {

packages/agtree/src/utils/string.ts

@@ -35,15 +35,17 @@ export class StringUtils {
      * @param searchedCharacter - Searched character
      * @param start - Start index
      * @param escapeCharacter - Escape character, \ by default
+     * @param end - End index (excluded)
      * @returns Index or -1 if the character not found
      */
     public static findNextUnescapedCharacter(
         pattern: string,
         searchedCharacter: string,
         start = 0,
         escapeCharacter: string = ESCAPE_CHARACTER,
+        end = pattern.length,
     ): number {
-        for (let i = start; i < pattern.length; i += 1) {
+        for (let i = start; i < end; i += 1) {
             // The searched character cannot be preceded by an escape
             if (pattern[i] === searchedCharacter && pattern[i - 1] !== escapeCharacter) {
                 return i;
@@ -59,15 +61,17 @@ export class StringUtils {
      * @param searchedCharacter - Searched character
      * @param start - Start index
      * @param escapeCharacter - Escape character, \ by default
+     * @param end - End index (Included)
      * @returns Index or -1 if the character not found
      */
     public static findNextUnescapedCharacterBackwards(
         pattern: string,
         searchedCharacter: string,
         start = pattern.length - 1,
         escapeCharacter: string = ESCAPE_CHARACTER,
+        end = 0,
     ): number {
-        for (let i = start; i >= 0; i -= 1) {
+        for (let i = start; i >= end; i -= 1) {
             // The searched character cannot be preceded by an escape
             if (pattern[i] === searchedCharacter && pattern[i - 1] !== escapeCharacter) {
                 return i;