class-pool.

        TYPES: i_rstrucinfo TYPE STANDARD TABLE OF rstrucinfo.
        TYPES: i_rfieldlist TYPE STANDARD TABLE OF rfieldlist.

        TYPES: i_rstrucinfo TYPE STANDARD TABLE OF rstrucinfo.
        TYPES: i_rfieldlist TYPE STANDARD TABLE OF rfieldlist.

        TYPES: i_rstrucinfo TYPE STANDARD TABLE OF rstrucinfo.
        TYPES: i_rfieldlist TYPE STANDARD TABLE OF rfieldlist.

        TYPES: i_rstrucinfo TYPE STANDARD TABLE OF rstrucinfo.
        TYPES: i_rfieldlist TYPE STANDARD TABLE OF rfieldlist.

class ZCL_CI_DIFFERENCE_ENGINE definition
  public
  create public .
public section.
  data CHANGEDFIELDS type FIELDNAME_TAB .
  data FIELDS type FIELDNAME_TAB .
  methods CONSTRUCTOR
    importing
      value(PROGNAME) type PROGNAME
      !REF_STRUCTURE type STRUKNAME .
  methods GET_CHANGED_FIELDS
    importing
      !STRING_1 type STRING
      !STRING_2 type STRING
    returning
      value(CHANGED_FIELDS) type FIELDNAME_TAB .

protected section.

private section.
  data I_RSTRUCINFO type I_RSTRUCINFO .
  data I_RFIELDLIST type I_RFIELDLIST .
  data PROGNAME type PROGNAME .
  data TEMP_PROGNAME type PROGNAME .
endclass. "ZCL_CI_DIFFERENCE_ENGINE definition

class ZCL_CI_DIFFERENCE_ENGINE implementation.

METHOD constructor .
  DATA: l_rstrucinfo TYPE rstrucinfo.
  DATA: l_rfieldlist TYPE rfieldlist.
  DATA: num_comps TYPE n.
  DATA: code TYPE TABLE OF char72.
  DATA: code_line TYPE char72.
  DATA: prog(8), msg(120), lin(3), wrd(10), off(3).
  APPEND:
  'PROGRAM SUBPOOL.'                                        TO code,
  'types:'                                                  TO code,
  'begin of line_type,'                                     TO code.
*get components of the named structure
  CALL FUNCTION 'GET_COMPONENT_LIST'
       EXPORTING
            program    = progname
            fieldname  = ref_structure
       TABLES
            components = i_rstrucinfo.
  LOOP AT i_rstrucinfo INTO l_rstrucinfo.
    CLEAR code_line.
    CASE l_rstrucinfo-type.
      WHEN 'C'.
        CONCATENATE l_rstrucinfo-compname '(' l_rstrucinfo-leng'),'
          INTO code_line.
        APPEND code_line TO code.
      WHEN 'D'.
        CONCATENATE l_rstrucinfo-compname 'type dats,'
          INTO code_line SEPARATED BY space.
        APPEND code_line TO code.
      WHEN 'I'.
        CONCATENATE l_rstrucinfo-compname 'type i,'
        INTO code_line SEPARATED BY space.
        APPEND code_line TO code.
      WHEN 'N'.
        CONCATENATE l_rstrucinfo-compname '(' l_rstrucinfo-leng')'
        INTO code_line.
      CONCATENATE code_line 'type n,' INTO code_line SEPARATED BY space.
        APPEND code_line TO code.
      WHEN 'P'.
        CONCATENATE l_rstrucinfo-compname '(' l_rstrucinfo-leng')'
        INTO code_line.
        CONCATENATE code_line 'type p decimals'
                 l_rstrucinfo-decs ','
        INTO code_line SEPARATED BY space.
        APPEND code_line TO code.
      WHEN 'T'.
        CONCATENATE l_rstrucinfo-compname 'type t,'
        INTO code_line SEPARATED BY space.
        APPEND code_line TO code.
    ENDCASE.
  ENDLOOP.
  APPEND:
  'end of line_type.'                                     TO code,
  'data:'                                                 TO code,
  'string_1 type string,'                                 TO code,
  'string_2 type string,'                                 TO code,
  'line1 type line_type,'                                 TO code,
  'line2 type line_type.'                                 TO code,
  'data: changed_fields type FIELDNAME_TAB.'              TO code,
  'data: fieldnames     type FIELDNAME_TAB.'              TO code,
  'data: begin of fieldstruc,'                            TO code,
  'fieldname type fieldname,'                             TO code,
  'end of fieldstruc.'                                    TO code,
  'data: fieldname type fieldname.'                       TO code,
  'field-symbols: '                                       TO code,
  '<comp1> type any, '                                    TO code,
  '<comp2> type any. '                                    TO code,
  'form set_fieldnames'                                   TO code,
  'using fieldname type fieldname.'                       TO code,
  'append fieldname to fieldnames.'                       TO code,
  'endform. '                                             TO code,
  'form difference  '                                     TO code,
  'tables changed_fields structure fieldstruc  '          TO code,
  'using string_1 type string                  '          TO code,
  '      string_2 type string.                 '          TO code,
  'line1 = string_1.           '                          TO code,
  'line2 = string_2.           '                          TO code,
  'loop at fieldnames into fieldname.'                    TO code,
  'assign component sy-tabix of '                         TO code,
  'structure line1 to <comp1>.  '                         TO code,
  'assign component sy-tabix of '                         TO code,
  'structure line2 to <comp2>.  '                         TO code,
  'if <comp1> ne <comp2>.'                                TO code,
  'append fieldname to changed_fields.'                   TO code,
  'endif.'                                                TO code,
  'endloop.'                                              TO code,
  'endform.'                                              TO code.
  GENERATE SUBROUTINE POOL code NAME prog
  MESSAGE msg
  LINE lin
  WORD wrd
  OFFSET off.
  IF sy-subrc <> 0.
    WRITE: / 'Error during generation in line', lin,
           / msg,
           / 'Word:', wrd, 'at offset', off.
  ELSE.
    me->temp_progname = prog.
    LOOP AT i_rstrucinfo INTO l_rstrucinfo.
      PERFORM set_fieldnames IN PROGRAM (prog)
      USING  l_rstrucinfo-compname.
      append l_rstrucinfo-compname to me->fields.
    ENDLOOP.
  ENDIF.
ENDMETHOD.

METHOD get_changed_fields.
  CLEAR me->changedfields.
  PERFORM difference IN PROGRAM (temp_progname)
  TABLES changed_fields
  USING string_1 string_2.
  me->changedfields = changed_fields.
ENDMETHOD.
endclass. "ZCL_CI_DIFFERENCE_ENGINE implementation