performs one undo step . concode_field_sep int currentVersionIndex concode_elem_sep int savePosition concode_elem_sep List<Delta<String>> deltas concode_elem_sep String currentVersion concode_field_sep void doSave concode_elem_sep boolean canUndo concode_elem_sep boolean isDirty concode_elem_sep List<String> split concode_elem_sep void setModelFromString concode_elem_sep void insertNewVersion concode_elem_sep void fireStackChanged concode_elem_sep void redo concode_elem_sep String join concode_elem_sep boolean canRedo concode_elem_sep int debugGetSize
void function ( ) { CCSMPre . isTrue ( canUndo ( ) , "srini_string" ) ; currentVersion = join ( deltas . get ( currentVersionIndex -- ) . backwardPatch ( split ( currentVersion ) ) ) ; setModelFromString ( currentVersion ) ; fireStackChanged ( ) ; }