PostgreSQL: compatibility with PCRE word boundary (#8141)

Allow the use of regex `\b` for word boundary (and `\B` for the opposite) even when using PostgreSQL.
Follow up of:
* https://github.com/FreshRSS/FreshRSS/pull/6706

For instance, `intitle:/\bnew\B/` will find *newest* but not *new* nor *renewal*.

Useful in particular to minimise the differences between PHP and database in:
* https://github.com/FreshRSS/FreshRSS/pull/7959

app/Models/EntryDAOPGSQL.php

@@ -43,6 +43,12 @@ class FreshRSS_EntryDAOPGSQL extends FreshRSS_EntryDAOSQLite {
 	protected static function sqlRegex(string $expression, string $regex, array &$values): string {
 		$matches = static::regexToSql($regex);
 		if (isset($matches['pattern'])) {
+			$replacements = [	// Convert some of the PCRE regex syntax to PostgreSQL
+				'\\b' => '\\y', // matches only at the beginning or end of a word (was: backspace)
+				'\\B' => '\\Y', // matches only at a point that is not the beginning or end of a word (was: backslash)
+			];
+			$matches['pattern'] = str_replace(array_keys($replacements), array_values($replacements), $matches['pattern']);
+
 			$matchType = $matches['matchType'] ?? '';
 			if (str_contains($matchType, 'm')) {
 				// newline-sensitive matching

docs/en/users/10_filter.md

@@ -155,6 +155,8 @@ As opposed to normal searches, special XML characters `<&">` are not escaped in
 	* [For MariaDB](https://mariadb.com/kb/en/pcre/);
 	* [For MySQL](https://dev.mysql.com/doc/refman/9.0/en/regexp.html#function_regexp-like).
 
+> ℹ️ Even with PostgreSQL, you are welcome to use `\b` for word boundary (and `\B` for the opposite), as there is an automatic translation to `\y` and `\Y`.
+
 ## By sorting by date
 
 You can change the sort order by clicking the toggle button available in the header.

docs/fr/users/03_Main_view.md

@@ -313,3 +313,5 @@ Contrairement aux recherches normales, les caractères spéciaux XML `<&">` ne s
 	* [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).
+
+> ℹ️ Même avec PostgreSQL, vous pouvez utiliser `\b` pour les limites de mots (et `\B` pour l’inverse), car une traduction automatique est effectuée vers `\y` et `\Y`.

tests/app/Models/SearchTest.php

@@ -751,6 +751,11 @@ final class SearchTest extends \PHPUnit\Framework\TestCase {
 				'(e.content ~ ? )',
 				['^ab\\M']
 			],
+			[
+				'intitle:/\\b\\d+/',
+				'(e.title ~ ? )',
+				['\\y\\d+']
+			],
 			[
 				'author:/^ab$/',
 				"(REPLACE(e.author, ';', '\n') ~ ? )",
@@ -819,6 +824,11 @@ final class SearchTest extends \PHPUnit\Framework\TestCase {
 				"(e.title REGEXP ? )",
 				['(?-i)(?m)^ab$']
 			],
+			[
+				'intitle:/\\b\\d+/',
+				"(e.title REGEXP ? )",
+				['(?-i)\\b\\d+']
+			],
 			[
 				'intext:/^ab$/m',
 				'(UNCOMPRESS(e.content_bin) REGEXP ?) )',