From 1a552bd60eab4a4b940d3896376b599e155d7da0 Mon Sep 17 00:00:00 2001
From: Alexandre Alapetite <alexandre@alapetite.fr>
Date: Fri, 6 Sep 2024 09:35:58 +0200
Subject: Regex search (#6706)

* Regex search
fix https://github.com/FreshRSS/FreshRSS/issues/3549

* Fix PHPStan

* Fix escape

* Fix ungreedy

* Initial support for regex search in PostgreSQL and MySQL

* Improvements, support MySQL

* Fix multiline

* Add support for SQLite

* A few tests

* Added author: and inurl: support, documentation

* author example

* Remove \b for now

* Disable regex sanitization for now

* Fix getInurlRegex

* getNotInurlRegex

* Quotes for inurl:

* Fix test

* Fix quoted tags + regex for tags
https://github.com/FreshRSS/FreshRSS/issues/6761

* Fix wrong regex detection

* Add MariaDB

* Fix logic

* Increase requirements for MySQL and MariaDB
Check support for multiline mode in MySQL

* Remove sanitizeRegexes()

* Allow searching HTML code
Allow searching for instance `/<pre>/`
Fix https://github.com/FreshRSS/FreshRSS/issues/6775#issuecomment-2331769883

* Doc regex search HTML

* Fix Doctype
---
 CONTRIBUTING.md                         |   2 +-
 README.fr.md                            |   2 +-
 README.md                               |   4 +-
 app/Models/DatabaseDAO.php              |  27 ++++-
 app/Models/Entry.php                    |  66 ++++++++++
 app/Models/EntryDAO.php                 | 116 +++++++++++++++++-
 app/Models/EntryDAOPGSQL.php            |  26 ++++
 app/Models/EntryDAOSQLite.php           |  21 ++++
 app/Models/Search.php                   | 207 ++++++++++++++++++++++++++------
 docs/en/admins/02_Prerequisites.md      |   2 +-
 docs/en/admins/DatabaseConfig.md        |   2 +-
 docs/en/developers/06_Reporting_Bugs.md |   2 +-
 docs/en/users/10_filter.md              |  29 ++++-
 docs/fr/contributing.md                 |   2 +-
 docs/fr/developers/02_Github.md         |   2 +-
 docs/fr/users/01_Installation.md        |   2 +-
 docs/fr/users/03_Main_view.md           |  29 ++++-
 lib/Minz/ModelPdo.php                   |   8 ++
 tests/app/Models/SearchTest.php         | 174 ++++++++++++++++++++++++++-
 19 files changed, 670 insertions(+), 53 deletions(-)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 66b28bb7e..724ae35f7 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -21,7 +21,7 @@ If you have to create a new ticket, try to apply the following advice:
 - We also need some information:
 	- Your FreshRSS version (on about page or `constants.php` file)
 	- Your server configuration: type of hosting, PHP version
-	- Your storage system (SQLite, MySQL, MariaDB, PostgreSQL)
+	- Your storage system (SQLite, PostgreSQL, MariaDB, MySQL)
 	- If possible, the related logs (PHP logs and FreshRSS logs under `data/users/your_user/log.txt`)
 
 ## Fix a bug
diff --git a/README.fr.md b/README.fr.md
index ad592227e..89a7f8714 100644
--- a/README.fr.md
+++ b/README.fr.md
@@ -66,7 +66,7 @@ FreshRSS n’est fourni avec aucune garantie.
 	* Extensions requises : [cURL](https://www.php.net/curl), [DOM](https://www.php.net/dom), [JSON](https://www.php.net/json), [XML](https://www.php.net/xml), [session](https://www.php.net/session), [ctype](https://www.php.net/ctype)
 	* Extensions recommandées : [PDO_SQLite](https://www.php.net/pdo-sqlite) (pour l’export/import), [GMP](https://www.php.net/gmp) (pour accès API sur plateformes < 64 bits), [IDN](https://www.php.net/intl.idn) (pour les noms de domaines internationalisés), [mbstring](https://www.php.net/mbstring) (pour le texte Unicode), [iconv](https://www.php.net/iconv) (pour conversion d’encodages), [ZIP](https://www.php.net/zip) (pour import/export), [zlib](https://www.php.net/zlib) (pour les flux compressés)
 	* Extension pour base de données : [PDO_PGSQL](https://www.php.net/pdo-pgsql) ou [PDO_SQLite](https://www.php.net/pdo-sqlite) ou [PDO_MySQL](https://www.php.net/pdo-mysql)
-* PostgreSQL 10+ ou SQLite ou MySQL 5.5.3+ ou MariaDB 5.5+
+* PostgreSQL 10+ ou SQLite ou MariaDB 10.0.5+ ou MySQL 8.0+
 
 # [Installation](https://freshrss.github.io/FreshRSS/fr/users/01_Installation.html)
 
diff --git a/README.md b/README.md
index 38db3cfc3..188d43192 100644
--- a/README.md
+++ b/README.md
@@ -61,12 +61,12 @@ FreshRSS comes with absolutely no warranty.
 	* Works on mobile (except a few features)
 * Light server running Linux or Windows
 	* It even works on Raspberry Pi 1 with response time under a second (tested with 150 feeds, 22k articles)
-* A web server: Apache2.4+ (recommended), nginx, lighttpd (not tested on others)
+* A Web server: Apache2.4+ (recommended), nginx, lighttpd (not tested on others)
 * PHP 8.1+
 	* Required extensions: [cURL](https://www.php.net/curl), [DOM](https://www.php.net/dom), [JSON](https://www.php.net/json), [XML](https://www.php.net/xml), [session](https://www.php.net/session), [ctype](https://www.php.net/ctype)
 	* Recommended extensions: [PDO_SQLite](https://www.php.net/pdo-sqlite) (for export/import), [GMP](https://www.php.net/gmp) (for API access on 32-bit platforms), [IDN](https://www.php.net/intl.idn) (for Internationalized Domain Names), [mbstring](https://www.php.net/mbstring) (for Unicode strings), [iconv](https://www.php.net/iconv) (for charset conversion), [ZIP](https://www.php.net/zip) (for import/export), [zlib](https://www.php.net/zlib) (for compressed feeds)
 	* Extension for database: [PDO_PGSQL](https://www.php.net/pdo-pgsql) or [PDO_SQLite](https://www.php.net/pdo-sqlite) or [PDO_MySQL](https://www.php.net/pdo-mysql)
-* PostgreSQL 10+ or SQLite or MySQL 5.5.3+ or MariaDB 5.5+
+* PostgreSQL 10+ or SQLite or MariaDB 10.0.5+ or MySQL 8.0+
 
 # [Installation](https://freshrss.github.io/FreshRSS/en/admins/03_Installation.html)
 
diff --git a/app/Models/DatabaseDAO.php b/app/Models/DatabaseDAO.php
index 363225cdb..ba0ee3e79 100644
--- a/app/Models/DatabaseDAO.php
+++ b/app/Models/DatabaseDAO.php
@@ -185,6 +185,30 @@ class FreshRSS_DatabaseDAO extends Minz_ModelPdo {
 		return $list;
 	}
 
+	private static ?string $staticVersion = null;
+	/**
+	 * To override the database version. Useful for testing.
+	 */
+	public static function setStaticVersion(?string $version): void {
+		self::$staticVersion = $version;
+	}
+
+	public function version(): string {
+		if (self::$staticVersion !== null) {
+			return self::$staticVersion;
+		}
+		static $version = null;
+		if ($version === null) {
+			$version = $this->fetchValue('SELECT version()') ?? '';
+		}
+		return $version;
+	}
+
+	final public function isMariaDB(): bool {
+		// MariaDB includes its name in version, but not MySQL
+		return str_contains($this->version(), 'MariaDB');
+	}
+
 	public function size(bool $all = false): int {
 		$db = FreshRSS_Context::systemConf()->db;
 
@@ -237,8 +261,7 @@ SQL;
 			$isMariaDB = false;
 
 			if ($this->pdo->dbType() === 'mysql') {
-				$dbVersion = $this->fetchValue('SELECT version()') ?? '';
-				$isMariaDB = stripos($dbVersion, 'MariaDB') !== false;	// MariaDB includes its name in version, but not MySQL
+				$isMariaDB = $this->isMariaDB();
 				if (!$isMariaDB) {
 					// MySQL does not support `DROP INDEX IF EXISTS` yet https://dev.mysql.com/doc/refman/8.3/en/drop-index.html
 					// but MariaDB does https://mariadb.com/kb/en/drop-index/
diff --git a/app/Models/Entry.php b/app/Models/Entry.php
index 4b331419b..415bc0235 100644
--- a/app/Models/Entry.php
+++ b/app/Models/Entry.php
@@ -631,27 +631,60 @@ HTML;
 						$ok &= stripos(implode(';', $this->authors), $author) !== false;
 					}
 				}
+				if ($ok && $filter->getAuthorRegex()) {
+					foreach ($filter->getAuthorRegex() as $author) {
+						$ok &= preg_match($author, implode("\n", $this->authors)) === 1;
+					}
+				}
 				if ($ok && $filter->getNotAuthor()) {
 					foreach ($filter->getNotAuthor() as $author) {
 						$ok &= stripos(implode(';', $this->authors), $author) === false;
 					}
 				}
+				if ($ok && $filter->getNotAuthorRegex()) {
+					foreach ($filter->getNotAuthorRegex() as $author) {
+						$ok &= preg_match($author, implode("\n", $this->authors)) === 0;
+					}
+				}
 				if ($ok && $filter->getIntitle()) {
 					foreach ($filter->getIntitle() as $title) {
 						$ok &= stripos($this->title, $title) !== false;
 					}
 				}
+				if ($ok && $filter->getIntitleRegex()) {
+					foreach ($filter->getIntitleRegex() as $title) {
+						$ok &= preg_match($title, $this->title) === 1;
+					}
+				}
 				if ($ok && $filter->getNotIntitle()) {
 					foreach ($filter->getNotIntitle() as $title) {
 						$ok &= stripos($this->title, $title) === false;
 					}
 				}
+				if ($ok && $filter->getNotIntitleRegex()) {
+					foreach ($filter->getNotIntitleRegex() as $title) {
+						$ok &= preg_match($title, $this->title) === 0;
+					}
+				}
 				if ($ok && $filter->getTags()) {
 					foreach ($filter->getTags() as $tag2) {
 						$found = false;
 						foreach ($this->tags as $tag1) {
 							if (strcasecmp($tag1, $tag2) === 0) {
 								$found = true;
+								break;
+							}
+						}
+						$ok &= $found;
+					}
+				}
+				if ($ok && $filter->getTagsRegex()) {
+					foreach ($filter->getTagsRegex() as $tag2) {
+						$found = false;
+						foreach ($this->tags as $tag1) {
+							if (preg_match($tag2, $tag1) === 1) {
+								$found = true;
+								break;
 							}
 						}
 						$ok &= $found;
@@ -663,6 +696,19 @@ HTML;
 						foreach ($this->tags as $tag1) {
 							if (strcasecmp($tag1, $tag2) === 0) {
 								$found = true;
+								break;
+							}
+						}
+						$ok &= !$found;
+					}
+				}
+				if ($ok && $filter->getNotTagsRegex()) {
+					foreach ($filter->getNotTagsRegex() as $tag2) {
+						$found = false;
+						foreach ($this->tags as $tag1) {
+							if (preg_match($tag2, $tag1) === 1) {
+								$found = true;
+								break;
 							}
 						}
 						$ok &= !$found;
@@ -673,11 +719,21 @@ HTML;
 						$ok &= stripos($this->link, $url) !== false;
 					}
 				}
+				if ($ok && $filter->getInurlRegex()) {
+					foreach ($filter->getInurlRegex() as $url) {
+						$ok &= preg_match($url, $this->link) === 1;
+					}
+				}
 				if ($ok && $filter->getNotInurl()) {
 					foreach ($filter->getNotInurl() as $url) {
 						$ok &= stripos($this->link, $url) === false;
 					}
 				}
+				if ($ok && $filter->getNotInurlRegex()) {
+					foreach ($filter->getNotInurlRegex() as $url) {
+						$ok &= preg_match($url, $this->link) === 0;
+					}
+				}
 				if ($ok && $filter->getSearch()) {
 					foreach ($filter->getSearch() as $needle) {
 						$ok &= (stripos($this->title, $needle) !== false || stripos($this->content, $needle) !== false);
@@ -688,6 +744,16 @@ HTML;
 						$ok &= (stripos($this->title, $needle) === false && stripos($this->content, $needle) === false);
 					}
 				}
+				if ($ok && $filter->getSearchRegex()) {
+					foreach ($filter->getSearchRegex() as $needle) {
+						$ok &= (preg_match($needle, $this->title) === 1 || preg_match($needle, $this->content) === 1);
+					}
+				}
+				if ($ok && $filter->getNotSearchRegex()) {
+					foreach ($filter->getNotSearchRegex() as $needle) {
+						$ok &= (preg_match($needle, $this->title) === 0 && preg_match($needle, $this->content) === 0);
+					}
+				}
 				if ($ok) {
 					return true;
 				}
diff --git a/app/Models/EntryDAO.php b/app/Models/EntryDAO.php
index 175df15c3..6a00e2108 100644
--- a/app/Models/EntryDAO.php
+++ b/app/Models/EntryDAO.php
@@ -27,6 +27,55 @@ class FreshRSS_EntryDAO extends Minz_ModelPdo {
 		return str_replace('INSERT INTO ', 'INSERT IGNORE INTO ', $sql);
 	}
 
+	/** @return array{pattern?:string,matchType?:string} */
+	protected static function regexToSql(string $regex): array {
+		if (preg_match('#^/(?P<pattern>.*)/(?P<matchType>[im]*)$#', $regex, $matches)) {
+			return $matches;
+		}
+		return [];
+	}
+
+	/** @param array<int|string> $values */
+	protected static function sqlRegex(string $expression, string $regex, array &$values): string {
+		// The implementation of this function is solely for MySQL and MariaDB
+		static $databaseDAOMySQL = null;
+		if ($databaseDAOMySQL === null) {
+			$databaseDAOMySQL = new FreshRSS_DatabaseDAO();
+		}
+
+		$matches = static::regexToSql($regex);
+		if (isset($matches['pattern'])) {
+			$matchType = $matches['matchType'] ?? '';
+			if ($databaseDAOMySQL->isMariaDB()) {
+				if (str_contains($matchType, 'm')) {
+					// multiline mode
+					$matches['pattern'] = '(?m)' . $matches['pattern'];
+				}
+				if (str_contains($matchType, 'i')) {
+					// case-insensitive match
+					$matches['pattern'] = '(?i)' . $matches['pattern'];
+				} else {
+					$matches['pattern'] = '(?-i)' . $matches['pattern'];
+				}
+				$values[] = $matches['pattern'];
+				return "{$expression} REGEXP ?";
+			} else {	// MySQL
+				if (!str_contains($matchType, 'i')) {
+					// Case-sensitive matching
+					$matchType .= 'c';
+				}
+				$values[] = $matches['pattern'];
+				return "REGEXP_LIKE({$expression},?,'{$matchType}')";
+			}
+		}
+		return '';
+	}
+
+	/** Register any needed SQL function for the query, e.g. application-defined functions for SQLite */
+	protected function registerSqlFunctions(string $sql): void {
+		// Nothing to do for MySQL
+	}
+
 	private function updateToMediumBlob(): bool {
 		if ($this->pdo->dbType() !== 'mysql') {
 			return false;
@@ -910,24 +959,44 @@ SQL;
 					$values[] = "%{$author}%";
 				}
 			}
+			if ($filter->getAuthorRegex() !== null) {
+				foreach ($filter->getAuthorRegex() as $author) {
+					$sub_search .= 'AND ' . static::sqlRegex("REPLACE({$alias}author, ';', '\n')", $author, $values) . ' ';
+				}
+			}
 			if ($filter->getIntitle() !== null) {
 				foreach ($filter->getIntitle() as $title) {
 					$sub_search .= 'AND ' . $alias . 'title LIKE ? ';
 					$values[] = "%{$title}%";
 				}
 			}
+			if ($filter->getIntitleRegex() !== null) {
+				foreach ($filter->getIntitleRegex() as $title) {
+					$sub_search .= 'AND ' . static::sqlRegex($alias . 'title', $title, $values) . ' ';
+				}
+			}
 			if ($filter->getTags() !== null) {
 				foreach ($filter->getTags() as $tag) {
 					$sub_search .= 'AND ' . static::sqlConcat('TRIM(' . $alias . 'tags) ', " ' #'") . ' LIKE ? ';
 					$values[] = "%{$tag} #%";
 				}
 			}
+			if ($filter->getTagsRegex() !== null) {
+				foreach ($filter->getTagsRegex() as $tag) {
+					$sub_search .= 'AND ' . static::sqlRegex("REPLACE(REPLACE({$alias}tags, ' #', '#'), '#', '\n')", $tag, $values) . ' ';
+				}
+			}
 			if ($filter->getInurl() !== null) {
 				foreach ($filter->getInurl() as $url) {
 					$sub_search .= 'AND ' . $alias . 'link LIKE ? ';
 					$values[] = "%{$url}%";
 				}
 			}
+			if ($filter->getInurlRegex() !== null) {
+				foreach ($filter->getInurlRegex() as $url) {
+					$sub_search .= 'AND ' . static::sqlRegex($alias . 'link', $url, $values) . ' ';
+				}
+			}
 
 			if ($filter->getNotAuthor() !== null) {
 				foreach ($filter->getNotAuthor() as $author) {
@@ -935,29 +1004,49 @@ SQL;
 					$values[] = "%{$author}%";
 				}
 			}
+			if ($filter->getNotAuthorRegex() !== null) {
+				foreach ($filter->getNotAuthorRegex() as $author) {
+					$sub_search .= 'AND NOT ' . static::sqlRegex("REPLACE({$alias}author, ';', '\n')", $author, $values) . ' ';
+				}
+			}
 			if ($filter->getNotIntitle() !== null) {
 				foreach ($filter->getNotIntitle() as $title) {
 					$sub_search .= 'AND ' . $alias . 'title NOT LIKE ? ';
 					$values[] = "%{$title}%";
 				}
 			}
+			if ($filter->getNotIntitleRegex() !== null) {
+				foreach ($filter->getNotIntitleRegex() as $title) {
+					$sub_search .= 'AND NOT ' . static::sqlRegex($alias . 'title', $title, $values) . ' ';
+				}
+			}
 			if ($filter->getNotTags() !== null) {
 				foreach ($filter->getNotTags() as $tag) {
 					$sub_search .= 'AND ' . static::sqlConcat('TRIM(' . $alias . 'tags) ', " ' #'") . ' NOT LIKE ? ';
 					$values[] = "%{$tag} #%";
 				}
 			}
+			if ($filter->getNotTagsRegex() !== null) {
+				foreach ($filter->getNotTagsRegex() as $tag) {
+					$sub_search .= 'AND NOT ' . static::sqlRegex("REPLACE(REPLACE({$alias}tags, ' #', '#'), '#', '\n')", $tag, $values) . ' ';
+				}
+			}
 			if ($filter->getNotInurl() !== null) {
 				foreach ($filter->getNotInurl() as $url) {
 					$sub_search .= 'AND ' . $alias . 'link NOT LIKE ? ';
 					$values[] = "%{$url}%";
 				}
 			}
+			if ($filter->getNotInurlRegex() !== null) {
+				foreach ($filter->getNotInurlRegex() as $url) {
+					$sub_search .= 'AND NOT ' . static::sqlRegex($alias . 'link', $url, $values) . ' ';
+				}
+			}
 
 			if ($filter->getSearch() !== null) {
 				foreach ($filter->getSearch() as $search_value) {
 					if (static::isCompressed()) {	// MySQL-only
-						$sub_search .= 'AND CONCAT(' . $alias . 'title, UNCOMPRESS(' . $alias . 'content_bin)) LIKE ? ';
+						$sub_search .= "AND CONCAT({$alias}title, '\\n', UNCOMPRESS({$alias}content_bin)) LIKE ? ";
 						$values[] = "%{$search_value}%";
 					} else {
 						$sub_search .= 'AND (' . $alias . 'title LIKE ? OR ' . $alias . 'content LIKE ?) ';
@@ -966,10 +1055,21 @@ SQL;
 					}
 				}
 			}
+			if ($filter->getSearchRegex() !== null) {
+				foreach ($filter->getSearchRegex() as $search_value) {
+					if (static::isCompressed()) {	// MySQL-only
+						$sub_search .= 'AND (' . static::sqlRegex($alias . 'title', $search_value, $values) .
+							' OR ' . static::sqlRegex("UNCOMPRESS({$alias}content_bin)", $search_value, $values) . ') ';
+					} else {
+						$sub_search .= 'AND (' . static::sqlRegex($alias . 'title', $search_value, $values) .
+							' OR ' . static::sqlRegex($alias . 'content', $search_value, $values) . ') ';
+					}
+				}
+			}
 			if ($filter->getNotSearch() !== null) {
 				foreach ($filter->getNotSearch() as $search_value) {
 					if (static::isCompressed()) {	// MySQL-only
-						$sub_search .= 'AND CONCAT(' . $alias . 'title, UNCOMPRESS(' . $alias . 'content_bin)) NOT LIKE ? ';
+						$sub_search .= "AND CONCAT({$alias}title, '\\n', UNCOMPRESS({$alias}content_bin)) NOT LIKE ? ";
 						$values[] = "%{$search_value}%";
 					} else {
 						$sub_search .= 'AND ' . $alias . 'title NOT LIKE ? AND ' . $alias . 'content NOT LIKE ? ';
@@ -978,6 +1078,17 @@ SQL;
 					}
 				}
 			}
+			if ($filter->getNotSearchRegex() !== null) {
+				foreach ($filter->getNotSearchRegex() as $search_value) {
+					if (static::isCompressed()) {	// MySQL-only
+						$sub_search .= 'AND NOT ' . static::sqlRegex($alias . 'title', $search_value, $values) .
+							' ANT NOT ' . static::sqlRegex("UNCOMPRESS({$alias}content_bin)", $search_value, $values) . ' ';
+					} else {
+						$sub_search .= 'AND NOT ' . static::sqlRegex($alias . 'title', $search_value, $values) .
+							' AND NOT ' . static::sqlRegex($alias . 'content', $search_value, $values) . ' ';
+					}
+				}
+			}
 
 			if ($sub_search != '') {
 				if ($isOpen) {
@@ -1039,6 +1150,7 @@ SQL;
 			if ($filterSearch !== '') {
 				$search .= 'AND (' . $filterSearch . ') ';
 				$values = array_merge($values, $filterValues);
+				$this->registerSqlFunctions($search);
 			}
 		}
 		return [$values, $search];
diff --git a/app/Models/EntryDAOPGSQL.php b/app/Models/EntryDAOPGSQL.php
index 8adeffe9e..fe157308c 100644
--- a/app/Models/EntryDAOPGSQL.php
+++ b/app/Models/EntryDAOPGSQL.php
@@ -23,6 +23,32 @@ class FreshRSS_EntryDAOPGSQL extends FreshRSS_EntryDAOSQLite {
 		return rtrim($sql, ' ;') . ' ON CONFLICT DO NOTHING';
 	}
 
+	#[\Override]
+	protected static function sqlRegex(string $expression, string $regex, array &$values): string {
+		$matches = static::regexToSql($regex);
+		if (isset($matches['pattern'])) {
+			$matchType = $matches['matchType'] ?? '';
+			if (str_contains($matchType, 'm')) {
+				// newline-sensitive matching
+				$matches['pattern'] = '(?m)' . $matches['pattern'];
+			}
+			$values[] = $matches['pattern'];
+			if (str_contains($matchType, 'i')) {
+				// case-insensitive matching
+				return "{$expression} ~* ?";
+			} else {
+				// case-sensitive matching
+				return "{$expression} ~ ?";
+			}
+		}
+		return '';
+	}
+
+	#[\Override]
+	protected function registerSqlFunctions(string $sql): void {
+		// Nothing to do for PostgreSQL
+	}
+
 	/** @param array<string|int> $errorInfo */
 	#[\Override]
 	protected function autoUpdateDb(array $errorInfo): bool {
diff --git a/app/Models/EntryDAOSQLite.php b/app/Models/EntryDAOSQLite.php
index 9c2b37623..6d604f25a 100644
--- a/app/Models/EntryDAOSQLite.php
+++ b/app/Models/EntryDAOSQLite.php
@@ -28,6 +28,27 @@ class FreshRSS_EntryDAOSQLite extends FreshRSS_EntryDAO {
 		return str_replace('INSERT INTO ', 'INSERT OR IGNORE INTO ', $sql);
 	}
 
+	#[\Override]
+	protected static function sqlRegex(string $expression, string $regex, array &$values): string {
+		$values[] = $regex;
+		return "{$expression} REGEXP ?";
+	}
+
+	#[\Override]
+	protected function registerSqlFunctions(string $sql): void {
+		if (!str_contains($sql, ' REGEXP ')) {
+			return;
+		}
+		// https://php.net/pdo.sqlitecreatefunction
+		// https://www.sqlite.org/lang_expr.html#the_like_glob_regexp_match_and_extract_operators
+		$this->pdo->sqliteCreateFunction('regexp',
+			function (string $pattern, string $text): bool {
+				return preg_match($pattern, $text) === 1;
+			},
+			2
+		);
+	}
+
 	/** @param array<string|int> $errorInfo */
 	#[\Override]
 	protected function autoUpdateDb(array $errorInfo): bool {
diff --git a/app/Models/Search.php b/app/Models/Search.php
index 7eaf741c3..755cf6b59 100644
--- a/app/Models/Search.php
+++ b/app/Models/Search.php
@@ -27,6 +27,8 @@ class FreshRSS_Search {
 	private ?array $label_names = null;
 	/** @var array<string>|null */
 	private ?array $intitle = null;
+	/** @var array<string>|null */
+	private ?array $intitle_regex = null;
 	/** @var int|false|null */
 	private $min_date = null;
 	/** @var int|false|null */
@@ -38,11 +40,19 @@ class FreshRSS_Search {
 	/** @var array<string>|null */
 	private ?array $inurl = null;
 	/** @var array<string>|null */
+	private ?array $inurl_regex = null;
+	/** @var array<string>|null */
 	private ?array $author = null;
 	/** @var array<string>|null */
+	private ?array $author_regex = null;
+	/** @var array<string>|null */
 	private ?array $tags = null;
 	/** @var array<string>|null */
+	private ?array $tags_regex = null;
+	/** @var array<string>|null */
 	private ?array $search = null;
+	/** @var array<string>|null */
+	private ?array $search_regex = null;
 
 	/** @var array<string>|null */
 	private ?array $not_entry_ids = null;
@@ -54,6 +64,8 @@ class FreshRSS_Search {
 	private ?array $not_label_names = null;
 	/** @var array<string>|null */
 	private ?array $not_intitle = null;
+	/** @var array<string>|null */
+	private ?array $not_intitle_regex = null;
 	/** @var int|false|null */
 	private $not_min_date = null;
 	/** @var int|false|null */
@@ -65,11 +77,19 @@ class FreshRSS_Search {
 	/** @var array<string>|null */
 	private ?array $not_inurl = null;
 	/** @var array<string>|null */
+	private ?array $not_inurl_regex = null;
+	/** @var array<string>|null */
 	private ?array $not_author = null;
 	/** @var array<string>|null */
+	private ?array $not_author_regex = null;
+	/** @var array<string>|null */
 	private ?array $not_tags = null;
 	/** @var array<string>|null */
+	private ?array $not_tags_regex = null;
+	/** @var array<string>|null */
 	private ?array $not_search = null;
+	/** @var array<string>|null */
+	private ?array $not_search_regex = null;
 
 	public function __construct(string $input) {
 		$input = self::cleanSearch($input);
@@ -156,9 +176,17 @@ class FreshRSS_Search {
 		return $this->intitle;
 	}
 	/** @return array<string>|null */
+	public function getIntitleRegex(): ?array {
+		return $this->intitle_regex;
+	}
+	/** @return array<string>|null */
 	public function getNotIntitle(): ?array {
 		return $this->not_intitle;
 	}
+	/** @return array<string>|null */
+	public function getNotIntitleRegex(): ?array {
+		return $this->not_intitle_regex;
+	}
 
 	public function getMinDate(): ?int {
 		return $this->min_date ?: null;
@@ -199,36 +227,68 @@ class FreshRSS_Search {
 		return $this->inurl;
 	}
 	/** @return array<string>|null */
+	public function getInurlRegex(): ?array {
+		return $this->inurl_regex;
+	}
+	/** @return array<string>|null */
 	public function getNotInurl(): ?array {
 		return $this->not_inurl;
 	}
+	/** @return array<string>|null */
+	public function getNotInurlRegex(): ?array {
+		return $this->not_inurl_regex;
+	}
 
 	/** @return array<string>|null */
 	public function getAuthor(): ?array {
 		return $this->author;
 	}
 	/** @return array<string>|null */
+	public function getAuthorRegex(): ?array {
+		return $this->author_regex;
+	}
+	/** @return array<string>|null */
 	public function getNotAuthor(): ?array {
 		return $this->not_author;
 	}
+	/** @return array<string>|null */
+	public function getNotAuthorRegex(): ?array {
+		return $this->not_author_regex;
+	}
 
 	/** @return array<string>|null */
 	public function getTags(): ?array {
 		return $this->tags;
 	}
 	/** @return array<string>|null */
+	public function getTagsRegex(): ?array {
+		return $this->tags_regex;
+	}
+	/** @return array<string>|null */
 	public function getNotTags(): ?array {
 		return $this->not_tags;
 	}
+	/** @return array<string>|null */
+	public function getNotTagsRegex(): ?array {
+		return $this->not_tags_regex;
+	}
 
 	/** @return array<string>|null */
 	public function getSearch(): ?array {
 		return $this->search;
 	}
 	/** @return array<string>|null */
+	public function getSearchRegex(): ?array {
+		return $this->search_regex;
+	}
+	/** @return array<string>|null */
 	public function getNotSearch(): ?array {
 		return $this->not_search;
 	}
+	/** @return array<string>|null */
+	public function getNotSearchRegex(): ?array {
+		return $this->not_search_regex;
+	}
 
 	/**
 	 * @param array<string>|null $anArray
@@ -253,11 +313,19 @@ class FreshRSS_Search {
 		return $value;
 	}
 
+	/**
+	 * @param array<string> $strings
+	 * @return array<string>
+	 */
+	private static function htmlspecialchars_decodes(array $strings): array {
+		return array_map(static fn(string $s) => htmlspecialchars_decode($s, ENT_QUOTES), $strings);
+	}
+
 	/**
 	 * Parse the search string to find entry (article) IDs.
 	 */
 	private function parseEntryIds(string $input): string {
-		if (preg_match_all('/\be:(?P<search>[0-9,]*)/', $input, $matches)) {
+		if (preg_match_all('/\\be:(?P<search>[0-9,]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$ids_lists = $matches['search'];
 			$this->entry_ids = [];
@@ -273,7 +341,7 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotEntryIds(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]e:(?P<search>[0-9,]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]e:(?P<search>[0-9,]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$ids_lists = $matches['search'];
 			$this->not_entry_ids = [];
@@ -289,7 +357,7 @@ class FreshRSS_Search {
 	}
 
 	private function parseFeedIds(string $input): string {
-		if (preg_match_all('/\bf:(?P<search>[0-9,]*)/', $input, $matches)) {
+		if (preg_match_all('/\\bf:(?P<search>[0-9,]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$ids_lists = $matches['search'];
 			$this->feed_ids = [];
@@ -307,7 +375,7 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotFeedIds(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]f:(?P<search>[0-9,]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]f:(?P<search>[0-9,]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$ids_lists = $matches['search'];
 			$this->not_feed_ids = [];
@@ -328,7 +396,7 @@ class FreshRSS_Search {
 	 * Parse the search string to find tags (labels) IDs.
 	 */
 	private function parseLabelIds(string $input): string {
-		if (preg_match_all('/\b[lL]:(?P<search>[0-9,]+|[*])/', $input, $matches)) {
+		if (preg_match_all('/\\b[lL]:(?P<search>[0-9,]+|[*])/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$ids_lists = $matches['search'];
 			$this->label_ids = [];
@@ -350,7 +418,7 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotLabelIds(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-][lL]:(?P<search>[0-9,]+|[*])/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-][lL]:(?P<search>[0-9,]+|[*])/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$ids_lists = $matches['search'];
 			$this->not_label_ids = [];
@@ -376,11 +444,11 @@ class FreshRSS_Search {
 	 */
 	private function parseLabelNames(string $input): string {
 		$names_lists = [];
-		if (preg_match_all('/\blabels?:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('/\\blabels?:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$names_lists = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
-		if (preg_match_all('/\blabels?:(?P<search>[^\s"]*)/', $input, $matches)) {
+		if (preg_match_all('/\\blabels?:(?P<search>[^\s"]*)/', $input, $matches)) {
 			$names_lists = array_merge($names_lists, $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -402,11 +470,11 @@ class FreshRSS_Search {
 	 */
 	private function parseNotLabelNames(string $input): string {
 		$names_lists = [];
-		if (preg_match_all('/(?<=\s|^)[!-]labels?:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]labels?:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$names_lists = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
-		if (preg_match_all('/(?<=\s|^)[!-]labels?:(?P<search>[^\s"]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]labels?:(?P<search>[^\\s"]*)/', $input, $matches)) {
 			$names_lists = array_merge($names_lists, $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -428,11 +496,15 @@ class FreshRSS_Search {
 	 * The search is the first word following the keyword.
 	 */
 	private function parseIntitleSearch(string $input): string {
-		if (preg_match_all('/\bintitle:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('#\\bintitle:(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->intitle_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/\\bintitle:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->intitle = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
-		if (preg_match_all('/\bintitle:(?P<search>[^\s"]*)/', $input, $matches)) {
+		if (preg_match_all('/\\bintitle:(?P<search>[^\s"]*)/', $input, $matches)) {
 			$this->intitle = array_merge($this->intitle ?: [], $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -444,11 +516,15 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotIntitleSearch(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]intitle:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('#(?<=\\s|^)[!-]intitle:(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->not_intitle_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-]intitle:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->not_intitle = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
-		if (preg_match_all('/(?<=\s|^)[!-]intitle:(?P<search>[^\s"]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]intitle:(?P<search>[^\s"]*)/', $input, $matches)) {
 			$this->not_intitle = array_merge($this->not_intitle ?: [], $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -465,11 +541,15 @@ class FreshRSS_Search {
 	 * a delimiter. Supported delimiters are single quote (') and double quotes (").
 	 */
 	private function parseAuthorSearch(string $input): string {
-		if (preg_match_all('/\bauthor:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('#\\bauthor:(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->author_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/\\bauthor:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->author = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
-		if (preg_match_all('/\bauthor:(?P<search>[^\s"]*)/', $input, $matches)) {
+		if (preg_match_all('/\\bauthor:(?P<search>[^\s"]*)/', $input, $matches)) {
 			$this->author = array_merge($this->author ?: [], $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -481,11 +561,15 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotAuthorSearch(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]author:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('#(?<=\\s|^)[!-]author:(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->not_author_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-]author:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->not_author = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
-		if (preg_match_all('/(?<=\s|^)[!-]author:(?P<search>[^\s"]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]author:(?P<search>[^\s"]*)/', $input, $matches)) {
 			$this->not_author = array_merge($this->not_author ?: [], $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -501,19 +585,41 @@ class FreshRSS_Search {
 	 * The search is the first word following the keyword.
 	 */
 	private function parseInurlSearch(string $input): string {
-		if (preg_match_all('/\binurl:(?P<search>[^\s]*)/', $input, $matches)) {
+		if (preg_match_all('#\\binurl:(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->inurl_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/\\binurl:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->inurl = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
-			$this->inurl = self::removeEmptyValues($this->inurl);
+		}
+		if (preg_match_all('/\\binurl:(?P<search>[^\\s]*)/', $input, $matches)) {
+			$this->inurl = $matches['search'];
+			$input = str_replace($matches[0], '', $input);
+		}
+		$this->inurl = self::removeEmptyValues($this->inurl);
+		if (empty($this->inurl)) {
+			$this->inurl = null;
 		}
 		return $input;
 	}
 
 	private function parseNotInurlSearch(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]inurl:(?P<search>[^\s]*)/', $input, $matches)) {
+		if (preg_match_all('#(?<=\\s|^)[!-]inurl:(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->not_inurl_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-]inurl:(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->not_inurl = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
-			$this->not_inurl = self::removeEmptyValues($this->not_inurl);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-]inurl:(?P<search>[^\\s]*)/', $input, $matches)) {
+			$this->not_inurl = $matches['search'];
+			$input = str_replace($matches[0], '', $input);
+		}
+		$this->not_inurl = self::removeEmptyValues($this->not_inurl);
+		if (empty($this->not_inurl)) {
+			$this->not_inurl = null;
 		}
 		return $input;
 	}
@@ -523,7 +629,7 @@ class FreshRSS_Search {
 	 * The search is the first word following the keyword.
 	 */
 	private function parseDateSearch(string $input): string {
-		if (preg_match_all('/\bdate:(?P<search>[^\s]*)/', $input, $matches)) {
+		if (preg_match_all('/\\bdate:(?P<search>[^\\s]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$dates = self::removeEmptyValues($matches['search']);
 			if (!empty($dates[0])) {
@@ -534,7 +640,7 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotDateSearch(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]date:(?P<search>[^\s]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]date:(?P<search>[^\\s]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$dates = self::removeEmptyValues($matches['search']);
 			if (!empty($dates[0])) {
@@ -550,7 +656,7 @@ class FreshRSS_Search {
 	 * The search is the first word following the keyword.
 	 */
 	private function parsePubdateSearch(string $input): string {
-		if (preg_match_all('/\bpubdate:(?P<search>[^\s]*)/', $input, $matches)) {
+		if (preg_match_all('/\\bpubdate:(?P<search>[^\\s]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$dates = self::removeEmptyValues($matches['search']);
 			if (!empty($dates[0])) {
@@ -561,7 +667,7 @@ class FreshRSS_Search {
 	}
 
 	private function parseNotPubdateSearch(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]pubdate:(?P<search>[^\s]*)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-]pubdate:(?P<search>[^\\s]*)/', $input, $matches)) {
 			$input = str_replace($matches[0], '', $input);
 			$dates = self::removeEmptyValues($matches['search']);
 			if (!empty($dates[0])) {
@@ -577,20 +683,44 @@ class FreshRSS_Search {
 	 * The search is the first word following the #.
 	 */
 	private function parseTagsSearch(string $input): string {
-		if (preg_match_all('/#(?P<search>[^\s]+)/', $input, $matches)) {
+		if (preg_match_all('%#(?P<search>/.*?(?<!\\\\)/[im]*)%', $input, $matches)) {
+			$this->tags_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/#(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->tags = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
-			$this->tags = self::removeEmptyValues($this->tags);
+		}
+		if (preg_match_all('/#(?P<search>[^\\s]+)/', $input, $matches)) {
+			$this->tags = $matches['search'];
+			$input = str_replace($matches[0], '', $input);
+		}
+		$this->tags = self::removeEmptyValues($this->tags);
+		if (empty($this->tags)) {
+			$this->tags = null;
+		} else {
 			$this->tags = self::decodeSpaces($this->tags);
 		}
 		return $input;
 	}
 
 	private function parseNotTagsSearch(string $input): string {
-		if (preg_match_all('/(?<=\s|^)[!-]#(?P<search>[^\s]+)/', $input, $matches)) {
+		if (preg_match_all('%(?<=\\s|^)[!-]#(?P<search>/.*?(?<!\\\\)/[im]*)%', $input, $matches)) {
+			$this->not_tags_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-]#(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+			$this->not_tags = $matches['search'];
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-]#(?P<search>[^\\s]+)/', $input, $matches)) {
 			$this->not_tags = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
-			$this->not_tags = self::removeEmptyValues($this->not_tags);
+		}
+		$this->not_tags = self::removeEmptyValues($this->not_tags);
+		if (empty($this->not_tags)) {
+			$this->not_tags = null;
+		} else {
 			$this->not_tags = self::decodeSpaces($this->not_tags);
 		}
 		return $input;
@@ -599,13 +729,18 @@ class FreshRSS_Search {
 	/**
 	 * Parse the search string to find search values.
 	 * Every word is a distinct search value using a delimiter.
-	 * Supported delimiters are single quote (') and double quotes (").
+	 * Supported delimiters are single quote (') and double quotes (") and regex (/).
 	 */
 	private function parseQuotedSearch(string $input): string {
 		$input = self::cleanSearch($input);
 		if ($input === '') {
 			return '';
 		}
+		if (preg_match_all('#(?<=\\s|^)(?<![!-\\\\])(?P<search>/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->search_regex = self::htmlspecialchars_decodes($matches['search']);
+			//TODO: Replace all those str_replace with PREG_OFFSET_CAPTURE
+			$input = str_replace($matches[0], '', $input);
+		}
 		if (preg_match_all('/(?<![!-])(?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->search = $matches['search'];
 			//TODO: Replace all those str_replace with PREG_OFFSET_CAPTURE
@@ -636,7 +771,11 @@ class FreshRSS_Search {
 		if ($input === '') {
 			return '';
 		}
-		if (preg_match_all('/(?<=\s|^)[!-](?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
+		if (preg_match_all('#(?<=\\s|^)[!-](?P<search>(?<!\\\\)/.*?(?<!\\\\)/[im]*)#', $input, $matches)) {
+			$this->not_search_regex = self::htmlspecialchars_decodes($matches['search']);
+			$input = str_replace($matches[0], '', $input);
+		}
+		if (preg_match_all('/(?<=\\s|^)[!-](?P<delim>[\'"])(?P<search>.*)(?P=delim)/U', $input, $matches)) {
 			$this->not_search = $matches['search'];
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -644,7 +783,7 @@ class FreshRSS_Search {
 		if ($input === '') {
 			return '';
 		}
-		if (preg_match_all('/(?<=\s|^)[!-](?P<search>[^\s]+)/', $input, $matches)) {
+		if (preg_match_all('/(?<=\\s|^)[!-](?P<search>[^\\s]+)/', $input, $matches)) {
 			$this->not_search = array_merge(is_array($this->not_search) ? $this->not_search : [], $matches['search']);
 			$input = str_replace($matches[0], '', $input);
 		}
@@ -656,7 +795,7 @@ class FreshRSS_Search {
 	 * Remove all unnecessary spaces in the search
 	 */
 	private static function cleanSearch(string $input): string {
-		$input = preg_replace('/\s+/', ' ', $input);
+		$input = preg_replace('/\\s+/', ' ', $input);
 		if (!is_string($input)) {
 			return '';
 		}
diff --git a/docs/en/admins/02_Prerequisites.md b/docs/en/admins/02_Prerequisites.md
index c54a7fd56..d38093b7a 100644
--- a/docs/en/admins/02_Prerequisites.md
+++ b/docs/en/admins/02_Prerequisites.md
@@ -9,7 +9,7 @@ You need to verify that your server can run FreshRSS before installing it. If yo
 | Web server    | **Apache 2.4**          | nginx, lighttpd<br />minimal compatibility with Apache 2.2    |
 | PHP           | **PHP 8.1+**            | FreshRSS 1.21/1.22: PHP 7.2+; FreshRSS 1.23/1.24: PHP 7.4+    |
 | PHP modules   | Required: libxml, cURL, JSON, PDO_MySQL, PCRE and ctype.<br />Required (32-bit only): GMP <br />Recommended: Zlib, mbstring, iconv, ZipArchive<br />*For the whole modules list see [Dockerfile](https://github.com/FreshRSS/FreshRSS/blob/edge/Docker/Dockerfile-Alpine#L7-L9)* | |
-| Database      | **PostgreSQL 10+**      | SQLite, MySQL 5.5.3+, MariaDB 5.5+   |
+| Database      | **PostgreSQL 10+**     | SQLite, MariaDB 10.0.5+, MySQL 8.0+ |
 | Browser       | **Firefox**             | Chrome, Opera, Safari, or Edge       |
 
 ## Getting the appropriate version of FreshRSS
diff --git a/docs/en/admins/DatabaseConfig.md b/docs/en/admins/DatabaseConfig.md
index 575749a7f..bc9b6a175 100644
--- a/docs/en/admins/DatabaseConfig.md
+++ b/docs/en/admins/DatabaseConfig.md
@@ -1,6 +1,6 @@
 # Database configuration
 
-FreshRSS supports the databases SQLite (built-in), PostgreSQL, MySQL / MariaDB.
+FreshRSS supports the databases SQLite (built-in), PostgreSQL, MariaDB / MySQL.
 
 While the default installation should be fine for most cases, additional tuning can be made.
 
diff --git a/docs/en/developers/06_Reporting_Bugs.md b/docs/en/developers/06_Reporting_Bugs.md
index 690330118..0c5d255ff 100644
--- a/docs/en/developers/06_Reporting_Bugs.md
+++ b/docs/en/developers/06_Reporting_Bugs.md
@@ -64,7 +64,7 @@ Remember to give the following information if you know it:
 1. Which browser? Which version?
 2. Which server: Apache, Nginx? Which version?
 3. Which version of PHP?
-4. Which database: SQLite, MySQL, MariaDB, PostgreSQL? Which version?
+4. Which database: SQLite, PostgreSQL, MariaDB, MySQL? Which version?
 5. Which distribution runs on the server? And… which version?
 
 ## How to provide feed data
diff --git a/docs/en/users/10_filter.md b/docs/en/users/10_filter.md
index 519130c14..943537471 100644
--- a/docs/en/users/10_filter.md
+++ b/docs/en/users/10_filter.md
@@ -49,7 +49,7 @@ You can use the search field to further refine results:
 * by author: `author:name` or `author:'composed name'`
 * by title: `intitle:keyword` or `intitle:'composed keyword'`
 * by URL: `inurl:keyword` or `inurl:'composed keyword'`
-* by tag: `#tag` or `#tag+with+whitespace`
+* by tag: `#tag` or `#tag+with+whitespace` or or `#'tag with whitespace'`
 * by free-text: `keyword` or `'composed keyword'`
 * by date of discovery, using the [ISO 8601 time interval format](http://en.wikipedia.org/wiki/ISO_8601#Time_intervals): `date:<date-interval>`
 	* From a specific day, or month, or year:
@@ -105,6 +105,8 @@ can be used to combine several search criteria with a logical *or* instead: `aut
 You don’t have to do anything special to combine multiple negative operators. Writing `!intitle:'thing1' !intitle:'thing2'` implies AND, see above. For more pointers on how AND and OR interact with negation, see [this GitHub comment](https://github.com/FreshRSS/FreshRSS/issues/3236#issuecomment-891219460).
 Additional reading: [De Morgan’s laws](https://en.wikipedia.org/wiki/De_Morgan%27s_laws).
 
+> ℹ️ Searches are applied to the raw HTML content
+
 Finally, parentheses may be used to express more complex queries, with basic negation support:
 
 * `(author:Alice OR intitle:hello) (author:Bob OR intitle:world)`
@@ -115,6 +117,31 @@ Finally, parentheses may be used to express more complex queries, with basic neg
 
 > ℹ️ If you need to search for a parenthesis, it needs to be escaped like `\(` or `\)`
 
+### Regex
+
+Text searches (including `author:`, `intitle:`, `inurl:`, `#`) may use regular expressions, which must be enclosed in `/ /`.
+
+Regex searches are case-sensitive by default, but can be made case-insensitive with the `i` modifier like: `/Alice/i`
+
+Supports multiline mode with `m` modifier like: `/^Alice/m`
+
+> ℹ️ `author:` is working with one author per line, so the multiline mode may advantageously be used, like: `author:/^Alice Dupont$/im`
+>
+> ℹ️ `#` is likewise working with one tag per line, so the multiline mode may advantageously be used, like: `#/^Hello World$/im`
+
+Example to search entries, which title starts with the *Lol* word, with any number of *o*: `intitle:/^Lo+l/i`
+
+As opposed to normal searches, HTML special characters are not escaped in regex searches, to allow searching HTML code, like: `/Hello <span>world<\/span>/`
+
+⚠️ Advanced regex syntax details depend on the regex engine used:
+
+* FreshRSS filter actions such as auto-mark-as-read and auto-favourite use [PHP preg_match](https://php.net/function.preg-match).
+* Regex searches depend on which database you are using:
+	* For SQLite, [PHP preg_match](https://php.net/function.preg-match) is used;
+	* [For PostgreSQL](https://www.postgresql.org/docs/current/functions-matching.html#FUNCTIONS-POSIX-REGEXP);
+	* [For MariaDB](https://mariadb.com/kb/en/pcre/);
+	* [For MySQL](https://dev.mysql.com/doc/refman/9.0/en/regexp.html#function_regexp-like).
+
 ## By sorting by date
 
 You can change the sort order by clicking the toggle button available in the header.
diff --git a/docs/fr/contributing.md b/docs/fr/contributing.md
index c1742d62b..0ffbe806e 100644
--- a/docs/fr/contributing.md
+++ b/docs/fr/contributing.md
@@ -32,7 +32,7 @@ Nous avons aussi besoin de quelques informations :
 
 * Votre version de FreshRSS (sur la page A propos) ou le fichier `constants.php`)
 * Votre configuration de serveur : type d’hébergement, version PHP
-* Quelle base de données : SQLite, MySQL, MariaDB, PostgreSQL ? Quelle version ?
+* Quelle base de données : SQLite, PostgreSQL, MariaDB, MySQL ? Quelle version ?
 * Si possible, les logs associés (logs PHP et logs FreshRSS sous `data/users/your_user/log.txt`)
 
 ## Corriger un bogue
diff --git a/docs/fr/developers/02_Github.md b/docs/fr/developers/02_Github.md
index 0f1aaeb0d..190eed9f2 100644
--- a/docs/fr/developers/02_Github.md
+++ b/docs/fr/developers/02_Github.md
@@ -100,7 +100,7 @@ Pensez à donner les informations suivantes si vous les connaissez :
 1. Quel navigateur ? Quelle version ?
 2. Quel serveur : Apache, Nginx ? Quelle version ?
 3. Quelle version de PHP ?
-4. Quelle base de données : SQLite, MySQL, MariaDB, PostgreSQL ? Quelle version ?
+4. Quelle base de données : SQLite, PostgreSQL, MariaDB, MySQL ? Quelle version ?
 5. Quelle distribution sur le serveur ? Et… quelle version ?
 
 ## Système de branches
diff --git a/docs/fr/users/01_Installation.md b/docs/fr/users/01_Installation.md
index 390052ec5..ecee8702b 100644
--- a/docs/fr/users/01_Installation.md
+++ b/docs/fr/users/01_Installation.md
@@ -9,7 +9,7 @@ Il est toutefois de votre responsabilité de vérifier que votre hébergement pe
 | Serveur web      | **Apache 2.4+**                                                                                                | nginx, lighttpd                |
 | PHP              | **PHP 8.1+**                                                                                                   |                                |
 | Modules PHP      | Requis : libxml, cURL, JSON, PDO_MySQL, PCRE et ctype<br />Requis (32 bits seulement) : GMP<br />Recommandé : Zlib, mbstring et iconv, ZipArchive<br />*Pour une liste complète des modules nécessaires voir le [Dockerfile](https://github.com/FreshRSS/FreshRSS/blob/edge/Docker/Dockerfile-Alpine#L7-L9)* |                                |
-| Base de données  | **PostgreSQL 10+** | SQLite, MySQL 5.5.3+, MariaDB 5.5+ |
+| Base de données  | **PostgreSQL 10+** | SQLite, MariaDB 10.0.5+, MySQL 8.0+ |
 | Navigateur       | **Firefox**                                                                                                    | Chrome, Opera, Safari, or Edge   |
 
 ## Choisir la bonne version de FreshRSS
diff --git a/docs/fr/users/03_Main_view.md b/docs/fr/users/03_Main_view.md
index 788143171..2af7a86b5 100644
--- a/docs/fr/users/03_Main_view.md
+++ b/docs/fr/users/03_Main_view.md
@@ -208,7 +208,7 @@ Il est possible d’utiliser le champ de recherche pour raffiner les résultats
 * par auteur : `author:nom` ou `author:'nom composé'`
 * par titre : `intitle:mot` ou `intitle:'mot composé'`
 * par URL : `inurl:mot` ou `inurl:'mot composé'`
-* par tag : `#tag`
+* par tag : `#tag` ou `#'tag avec espace'`
 * par texte libre : `mot` ou `'mot composé'`
 * par date d’ajout, en utilisant le [format ISO 8601 d’intervalle entre deux dates](https://fr.wikipedia.org/wiki/ISO_8601#Intervalle_entre_deux_dates) : `date:<intervalle-de-dates>`
 	* D’un jour spécifique, ou mois, ou année :
@@ -264,6 +264,8 @@ encore plus précis, et il est autorisé d’avoir plusieurs instances de :
 Combiner plusieurs critères implique un *et* logique, mais le mot clef `OR`
 peut être utilisé pour combiner plusieurs critères avec un *ou* logique : `author:Dupont OR author:Dupond`
 
+> ℹ️ Les recherches sont effectuées sur le code HTML brut
+
 Enfin, les parenthèses peuvent être utilisées pour des expressions plus complexes, avec un support basique de la négation :
 
 * `(author:Alice OR intitle:bonjour) (author:Bob OR intitle:monde)`
@@ -273,3 +275,28 @@ Enfin, les parenthèses peuvent être utilisées pour des expressions plus compl
 * `!(S:1 OR S:2)`
 
 > ℹ️ Si vous devez chercher une parenthèse, elle doit être *échappée* comme suit : `\(` ou `\)`
+
+#### Regex
+
+Les recherches de texte (incluant `author:`, `intitle:`, `inurl:`, `#`) peuvent utiliser les expressions régulières qui doivent être exprimées comme `/ /`.
+
+Les recherches regex sont sensibles à la casse, mais peuvent être rendues insensibles à la casse avec l’option de recherche `i` comme : `/Alice/i`
+
+Le mode multilignes peut être activé avec l’option de recherche `m` comme : `/^Alice/m`
+
+> ℹ️ `author:` fonctionne avec un auteur par ligne, ce qui fait que le mode multilignes peut être avantageux, comme : `author:/^Alice Doe$/im`
+>
+> ℹ️ `#` fonctionne également avec un tag par line, ce qui fait que le mode multilignes peut être avantageux, comme : `#/^Hello World$/im`
+
+Exemple pour rechercher des articles dont le titre commence par le mot *Lol* avec un nombre indéterminé de *o*: `intitle:/^Lo+l/i`
+
+Contrairement aux recherches normales, les caractères spéciaux HTML ne sont pas encodés dans les recherches regex, afin de permettre de chercher du code HTML, comme : `/Bonjour <span>à tous<\/span>/`
+
+⚠️ Les détails de syntaxe regex avancée dépendent du moteur regex utilisé :
+
+* Les filtres d’action de FreshRSS comme marquer-automatiquement-comme-lu et mettre-automatiquement-en-favori utilisent [PHP preg_match](https://php.net/function.preg-match).
+* Les recherches regex dépendent de la base de données utilisée :
+	* Pour SQLite, [PHP preg_match](https://php.net/function.preg-match) est utilisé ;
+	* [Pour PostgreSQL](https://www.postgresql.org/docs/current/functions-matching.html#FUNCTIONS-POSIX-REGEXP) ;
+	* [Pour MariaDB](https://mariadb.com/kb/en/pcre/) ;
+	* [Pour MySQL](https://dev.mysql.com/doc/refman/9.0/en/regexp.html#function_regexp-like).
diff --git a/lib/Minz/ModelPdo.php b/lib/Minz/ModelPdo.php
index f27ae5dc7..7804b3302 100644
--- a/lib/Minz/ModelPdo.php
+++ b/lib/Minz/ModelPdo.php
@@ -16,6 +16,11 @@ class Minz_ModelPdo {
 	 */
 	public static bool $usesSharedPdo = true;
 
+	/**
+	 * If true, the connection to the database will be a dummy one. Useful for unit tests.
+	 */
+	public static bool $dummyConnection = false;
+
 	private static ?Minz_Pdo $sharedPdo = null;
 
 	private static string $sharedCurrentUser = '';
@@ -97,6 +102,9 @@ class Minz_ModelPdo {
 			$this->pdo = $currentPdo;
 			return;
 		}
+		if (self::$dummyConnection) {
+			return;
+		}
 		if ($currentUser == null) {
 			throw new Minz_PDOConnectionException('Current user must not be empty!', '', Minz_Exception::ERROR);
 		}
diff --git a/tests/app/Models/SearchTest.php b/tests/app/Models/SearchTest.php
index 27943cdb2..a25adc160 100644
--- a/tests/app/Models/SearchTest.php
+++ b/tests/app/Models/SearchTest.php
@@ -124,10 +124,10 @@ class SearchTest extends PHPUnit\Framework\TestCase {
 	public static function provideInurlSearch(): array {
 		return [
 			['inurl:word1', ['word1'], null],
-			['inurl: word1', [], ['word1']],
+			['inurl: word1', null, ['word1']],
 			['inurl:123', ['123'], null],
 			['inurl:word1 word2', ['word1'], ['word2']],
-			['inurl:"word1 word2"', ['"word1'], ['word2"']],
+			['inurl:"word1 word2"', ['word1 word2'], null],
 			['inurl:word1 word2 inurl:word3', ['word1', 'word3'], ['word2']],
 			["inurl:word1 'word2 word3' word4", ['word1'], ['word2 word3', 'word4']],
 			['inurl:word1+word2', ['word1+word2'], null],
@@ -196,7 +196,7 @@ class SearchTest extends PHPUnit\Framework\TestCase {
 			['# word1', null, ['#', 'word1']],
 			['#123', ['123'], null],
 			['#word1 word2', ['word1'], ['word2']],
-			['#"word1 word2"', ['"word1'], ['word2"'],],
+			['#"word1 word2"', ['word1 word2'], null],
 			['#word1 #word2', ['word1', 'word2'], null],
 			["#word1 'word2 word3' word4", ['word1'], ['word2 word3', 'word4']],
 			['#word1+word2', ['word1 word2'], null]
@@ -442,4 +442,172 @@ class SearchTest extends PHPUnit\Framework\TestCase {
 			],
 		];
 	}
+
+	/**
+	 * @dataProvider provideRegexPostreSQL
+	 * @param array<string> $values
+	 */
+	public function test__regex_postgresql(string $input, string $sql, array $values): void {
+		[$filterValues, $filterSearch] = FreshRSS_EntryDAOPGSQL::sqlBooleanSearch('e.', new FreshRSS_BooleanSearch($input));
+		self::assertEquals(trim($sql), trim($filterSearch));
+		self::assertEquals($values, $filterValues);
+	}
+
+	/** @return array<array<mixed>> */
+	public function provideRegexPostreSQL(): array {
+		return [
+			[
+				'intitle:/^ab$/',
+				'(e.title ~ ? )',
+				['^ab$']
+			],
+			[
+				'intitle:/^ab$/i',
+				'(e.title ~* ? )',
+				['^ab$']
+			],
+			[
+				'intitle:/^ab$/m',
+				'(e.title ~ ? )',
+				['(?m)^ab$']
+			],
+			[
+				'intitle:/^ab\\M/',
+				'(e.title ~ ? )',
+				['^ab\\M']
+			],
+			[
+				'author:/^ab$/',
+				"(REPLACE(e.author, ';', '\n') ~ ? )",
+				['^ab$']
+			],
+			[
+				'inurl:/^ab$/',
+				'(e.link ~ ? )',
+				['^ab$']
+			],
+			[
+				'/^ab$/',
+				'((e.title ~ ? OR e.content ~ ?) )',
+				['^ab$', '^ab$']
+			],
+			[
+				'!/^ab$/',
+				'(NOT e.title ~ ? AND NOT e.content ~ ? )',
+				['^ab$', '^ab$']
+			],
+			[	// Not a regex
+				'inurl:https://example.net/test/',
+				'(e.link LIKE ? )',
+				['%https://example.net/test/%']
+			],
+			[	// Not a regex
+				'https://example.net/test/',
+				'((e.title LIKE ? OR e.content LIKE ?) )',
+				['%https://example.net/test/%', '%https://example.net/test/%']
+			],
+		];
+	}
+
+	/**
+	 * @dataProvider provideRegexMariaDB
+	 * @param array<string> $values
+	 */
+	public function test__regex_mariadb(string $input, string $sql, array $values): void {
+		FreshRSS_DatabaseDAO::$dummyConnection = true;
+		FreshRSS_DatabaseDAO::setStaticVersion('11.4.3-MariaDB-ubu2404');
+		[$filterValues, $filterSearch] = FreshRSS_EntryDAO::sqlBooleanSearch('e.', new FreshRSS_BooleanSearch($input));
+		self::assertEquals(trim($sql), trim($filterSearch));
+		self::assertEquals($values, $filterValues);
+	}
+
+	/** @return array<array<mixed>> */
+	public function provideRegexMariaDB(): array {
+		return [
+			[
+				'intitle:/^ab$/',
+				"(e.title REGEXP ? )",
+				['(?-i)^ab$']
+			],
+			[
+				'intitle:/^ab$/i',
+				"(e.title REGEXP ? )",
+				['(?i)^ab$']
+			],
+			[
+				'intitle:/^ab$/m',
+				"(e.title REGEXP ? )",
+				['(?-i)(?m)^ab$']
+			],
+		];
+	}
+
+	/**
+	 * @dataProvider provideRegexMySQL
+	 * @param array<string> $values
+	 */
+	public function test__regex_mysql(string $input, string $sql, array $values): void {
+		FreshRSS_DatabaseDAO::$dummyConnection = true;
+		FreshRSS_DatabaseDAO::setStaticVersion('9.0.1');
+		[$filterValues, $filterSearch] = FreshRSS_EntryDAO::sqlBooleanSearch('e.', new FreshRSS_BooleanSearch($input));
+		self::assertEquals(trim($sql), trim($filterSearch));
+		self::assertEquals($values, $filterValues);
+	}
+
+	/** @return array<array<mixed>> */
+	public function provideRegexMySQL(): array {
+		return [
+			[
+				'intitle:/^ab$/',
+				"(REGEXP_LIKE(e.title,?,'c') )",
+				['^ab$']
+			],
+			[
+				'intitle:/^ab$/i',
+				"(REGEXP_LIKE(e.title,?,'i') )",
+				['^ab$']
+			],
+			[
+				'intitle:/^ab$/m',
+				"(REGEXP_LIKE(e.title,?,'mc') )",
+				['^ab$']
+			],
+		];
+	}
+
+	/**
+	 * @dataProvider provideRegexSQLite
+	 * @param array<string> $values
+	 */
+	public function test__regex_sqlite(string $input, string $sql, array $values): void {
+		[$filterValues, $filterSearch] = FreshRSS_EntryDAOSQLite::sqlBooleanSearch('e.', new FreshRSS_BooleanSearch($input));
+		self::assertEquals(trim($sql), trim($filterSearch));
+		self::assertEquals($values, $filterValues);
+	}
+
+	/** @return array<array<mixed>> */
+	public function provideRegexSQLite(): array {
+		return [
+			[
+				'intitle:/^ab$/',
+				"(e.title REGEXP ? )",
+				['/^ab$/']
+			],
+			[
+				'intitle:/^ab$/i',
+				"(e.title REGEXP ? )",
+				['/^ab$/i']
+			],
+			[
+				'intitle:/^ab$/m',
+				"(e.title REGEXP ? )",
+				['/^ab$/m']
+			],
+			[
+				'intitle:/^ab\\b/',
+				'(e.title REGEXP ? )',
+				['/^ab\\b/']
+			],
+		];
+	}
 }
-- 
cgit v1.2.3