question: @ SuppressWarnings ( "fallthrough" ) public static Automaton toAutomaton ( Term wildcardquery ) { List < Automaton > automata = new ArrayList < > ( ) ; String wildcardText = wildcardquery . text ( ) ; for ( int i = 0 ; i < wildcardText . length ( ) ; ) { final int c = wildcardText . codePointAt ( i ) ; int length = Character . charCount ( c ) ; switch ( c ) { case WILDCARD_STRING : automata . add ( Automata . makeAnyString ( ) ) ; break ; case WILDCARD_CHAR : automata . add ( Automata . makeAnyChar ( ) ) ; break ; case WILDCARD_ESCAPE : if ( i + length < wildcardText . length ( ) ) { final int nextChar = wildcardText . codePointAt ( i + length ) ; length += Character . charCount ( nextChar ) ; automata . add ( Automata . makeChar ( nextChar ) ) ; break ; } default : automata . add ( Automata . makeChar ( c ) ) ; } i += length ; } return Operations . concatenate ( automata ) ; }
target:  Convert Lucene wildcard syntax into an automaton.