use unique in x+x->x regexp optimisation

alib2algo/src/regexp/simplify/RegExpOptimizeUnboundedPart.cxx

@@ -234,17 +234,12 @@ bool RegExpOptimize::A4( UnboundedRegExpAlternation * const & node ) const {
 	 *
 	 * As we always sort in optimization, we can use the first version, but A4 must be __always__ called __after__ A2
 	 */
-	bool optimized = false;
-	if(node->getChildren ( ).size() != 0) for( auto it = std::next( node->getChildren ( ).begin( ) ); it != node->getChildren ( ).end( ); ) {
-		if ( ** it == ** std::prev( it ) ) {
-			it = node->getChildren ( ).erase( it );
-			optimized = true;
-		} else
-			it ++;
-	}
-	return optimized;
+	auto cmp = [ ]( const std::smart_ptr < UnboundedRegExpElement > & a, const std::smart_ptr < UnboundedRegExpElement > & b ) -> bool { return *a == *b; };
+	size_t size = node->getChildren ( ).size ( );
+	std::unique ( node->getChildren ( ).begin ( ), node->getChildren ( ).end ( ), cmp);
+	return size != node->getChildren ( ).size ( );
 }
 /**