question: String renameFile ( String inputFilename ) { for ( Pattern searchExp : regexMappings . keySet ( ) ) { Matcher matcher = searchExp . matcher ( inputFilename ) ; if ( matcher . find ( ) ) { String renamed = matcher . replaceFirst ( regexMappings . get ( searchExp ) ) ; return FILE_SEP_CHAR_MATCHER . trimLeadingFrom ( renamed ) ; } } throw new MoeProblem ( "Cannot find a rename mapping that covers file %s. " + "Every file needs an applicable renaming rule." , inputFilename ) ; }
target:  Returns the filename according to the rules in mappings.