1 files changed, 89 insertions, 0 deletions
diff --git a/MLEB/Translate/src/MessageValidator/Validators/EscapeCharacterValidator.php b/MLEB/Translate/src/MessageValidator/Validators/EscapeCharacterValidator.php
new file mode 100644
index 00000000..05d79827
--- /dev/null
+++ b/MLEB/Translate/src/MessageValidator/Validators/EscapeCharacterValidator.php
@@ -0,0 +1,89 @@
+<?php
+declare( strict_types = 1 );
+
+namespace MediaWiki\Extensions\Translate\MessageValidator\Validators;
+
+use MediaWiki\Extensions\Translate\Validation\MessageValidator;
+use MediaWiki\Extensions\Translate\Validation\ValidationIssue;
+use MediaWiki\Extensions\Translate\Validation\ValidationIssues;
+use TMessage;
+
+/**
+ * Ensures that only the specified escape characters are present.
+ * @license GPL-2.0-or-later
+ * @since 2020.01
+ */
+class EscapeCharacterValidator implements MessageValidator {
+	/** @var string[] */
+	protected $allowedCharacters;
+
+	/** @var string */
+	protected $regex;
+
+	/** List of valid escape characters recognized. */
+	private const VALID_CHARS = [ '\t', '\n', '\\\'', '\"', '\f', '\r', '\a', '\b', '\\\\' ];
+
+	public function __construct( array $params ) {
+		$this->allowedCharacters = $params['values'] ?? [];
+
+		if ( $this->allowedCharacters === [] || !is_array( $this->allowedCharacters ) ) {
+			throw new \InvalidArgumentException(
+				'No values provided for EscapeCharacter validator.'
+			);
+		}
+
+		$this->regex = $this->buildRegex( $this->allowedCharacters );
+	}
+
+	public function getIssues( TMessage $message, string $targetLanguage ): ValidationIssues {
+		$issues = new ValidationIssues();
+		$translation = $message->translation();
+		preg_match_all( "/$this->regex/U", $translation, $transVars );
+
+		// Check for missing variables in the translation
+		$params = $transVars[0];
+		if ( count( $params ) ) {
+			$messageParams = [
+				[ 'PARAMS', $params ],
+				[ 'COUNT', count( $params ) ],
+				[ 'PARAMS', $this->allowedCharacters ],
+				[ 'COUNT', count( $this->allowedCharacters ) ]
+			];
+
+			$issue =
+				new ValidationIssue(
+					'escape', 'invalid', 'translate-checks-escape', $messageParams
+				);
+			$issues->add( $issue );
+		}
+
+		return $issues;
+	}
+
+	private function buildRegex( array $allowedCharacters ): string {
+		$regex = '\\\\[^';
+		$prefix = '';
+		foreach ( $allowedCharacters as $character ) {
+			if ( !in_array( $character, self::VALID_CHARS ) ) {
+				throw new \InvalidArgumentException(
+					"Invalid escape character encountered: $character during configuration." .
+					'Valid escape characters include: ' . implode( ', ', self::VALID_CHARS )
+				);
+			}
+
+			if ( $character !== '\\' ) {
+				$character = stripslashes( $character );
+				// negative look ahead, to avoid "\\ " being treated as an accidental escape
+				$prefix = '(?<!\\\\)';
+			}
+
+			// This is done because in the regex we need slashes for some characters such as
+			// \", \', but not for others such as \n, \t etc
+			$normalizedChar = addslashes( $character );
+			$regex .= $normalizedChar;
+		}
+		$regex .= ']';
+
+		return $prefix . $regex;
+	}
+}