Tree type report in ABAP

REPORT ZRJNTRIAL_TREE LINE-COUNT 65
LINE-SIZE 80
NO STANDARD PAGE
HEADING.
*********************************************************************
DATA: BEGIN OF ITEMS OCCURS 100,
ID(10),
PARENT_ID(10),
TEXT(20),
SYMBOL,
END OF ITEMS,
TABIX_STACK LIKE SY-TABIX OCCURS 10 WITH HEADER LINE,
ITEMS_SHOW LIKE ITEMS OCCURS 100 WITH HEADER LINE.
INCLUDE .
* append sample items (mixed order)
PERFORM APPEND_ITEM USING:
'1' '' 'Food',
'2' '' 'Drinks',
'12' '9' 'Jack Daniels',
'17' '11' 'Bosch',
'3' '' 'Tools',
'4' '1' 'Meat',
'16' '11' 'Metabo',
'5' '1' 'Chocolate',
'6' '2' 'Alcoholic',
'8' '4' 'Pork',
'10' '5' 'Milka',
'11' '3' 'Drills',
'13' '9' 'Jim Beam',
'7' '4' 'Beef',
'14' '2' 'Non-alcoholic',
'35' '31' 'Teran',
'9' '6' 'Whiskey',
'15' '14' 'Coca-cola',
'18' '6' 'Wine',
'28' '18' 'Croatia',
'33' '28' 'Slavonia',
'34' '28' 'Istria',
'29' '18' 'Hungary',
'30' '29' 'Tokaj',
'19' '33' 'Enjingi',
'20' '33' 'Zdjelarevic',
'22' '19' 'Riesling',
'23' '19' 'Chardonnay',
'24' '20' 'Riesling',
'32' '31' 'Malvazija',
'25' '20' 'Merlot',
'31' '34' 'Tomasevic'.

* show initial list (items with level 0 - parentless items)
LOOP AT ITEMS WHERE PARENT_ID = ''.
MOVE-CORRESPONDING ITEMS TO ITEMS_SHOW.
ITEMS_SHOW-SYMBOL = '+'.
APPEND ITEMS_SHOW.
ENDLOOP.
PERFORM PRINT_TREE TABLES ITEMS_SHOW.

* at line-selection - when the node is opened/closed or item double-clk
AT LINE-SELECTION.
READ TABLE ITEMS WITH KEY PARENT_ID = ITEMS_SHOW-ID. "see 'hide'
IF SY-SUBRC = 0. "item has children - expand or collapse
SY-LSIND = 0.
PERFORM EXPAND_COLLAPSE USING ITEMS_SHOW-ID.
PERFORM PRINT_TREE TABLES ITEMS_SHOW.
ELSE. "item has NO children - perform some action
READ TABLE ITEMS WITH KEY ID = ITEMS_SHOW-ID.
WRITE: 'Action performed on item "' NO-GAP, ITEMS-TEXT NO-GAP,
'", id.', ITEMS-ID.
ENDIF.

* form print_tree
FORM PRINT_TREE TABLES ITEMS STRUCTURE ITEMS.
DATA: V_TABIX LIKE SY-TABIX,
START_TABIX LIKE SY-TABIX,
V_LEVEL LIKE SY-TFILL,
V_OFFSET TYPE I,
V_ID LIKE ITEMS-ID,
V_PARENT_ID LIKE ITEMS-PARENT_ID,
V_PARENT_ID_FOR_VLINE LIKE ITEMS-PARENT_ID,
V_PREV_LEVEL TYPE I,
V_ITEMS_COUNT LIKE SY-TFILL,
V_VLINES_STRING(200).
CHECK NOT ITEMS[] IS INITIAL.
SORT ITEMS BY PARENT_ID ID.
READ TABLE ITEMS INDEX 1.
V_PARENT_ID = ITEMS-PARENT_ID.
START_TABIX = 1.
REFRESH TABIX_STACK.
DO.
LOOP AT ITEMS FROM START_TABIX.
V_TABIX = START_TABIX = SY-TABIX."remember current index
V_ID = ITEMS-ID.
V_PARENT_ID_FOR_VLINE = ITEMS-PARENT_ID.
* decrease level and exit loop if parent not the same as previous
IF ITEMS-PARENT_ID NE V_PARENT_ID.
PERFORM READ_FROM_STACK CHANGING START_TABIX. "level = NoOfRecs
READ TABLE ITEMS INDEX START_TABIX.
V_PARENT_ID = ITEMS-PARENT_ID.
ADD 1 TO START_TABIX. "next loop starts from parent index + 1
* clear vline
IF V_LEVEL > 1.
V_OFFSET = 2 + ( V_LEVEL - 2 ) * 3.
IF V_LEVEL = 1. V_OFFSET = 1. ENDIF.
V_VLINES_STRING+V_OFFSET = ' '.
ENDIF.
EXIT.
ENDIF.
V_PARENT_ID = ITEMS-PARENT_ID.
* write item
FORMAT COLOR OFF.
DESCRIBE TABLE TABIX_STACK LINES V_LEVEL."level is no of
StackRecs
WRITE: / V_VLINES_STRING.
V_OFFSET = V_LEVEL * 3.
IF V_LEVEL NE 0.
IF V_PREV_LEVEL < V_LEVEL.
WRITE: AT V_OFFSET '|', / ''.
WRITE: / V_VLINES_STRING.
ENDIF.
V_OFFSET = V_LEVEL * 3.
WRITE AT V_OFFSET '|--'.
ENDIF.
V_OFFSET = V_OFFSET + 3.
CASE ITEMS-SYMBOL.
WHEN '+'.
WRITE AT V_OFFSET SYM_PLUS_FOLDER AS SYMBOL
COLOR 4 INTENSIFIED HOTSPOT.
WHEN '-'.
WRITE AT V_OFFSET SYM_MINUS_FOLDER AS SYMBOL
COLOR 4 INTENSIFIED HOTSPOT.
WHEN OTHERS. FORMAT COLOR 5.
ENDCASE.
WRITE: ITEMS-TEXT.
V_PREV_LEVEL = V_LEVEL.
HIDE: ITEMS-ID.
ADD 1 TO V_ITEMS_COUNT.
READ TABLE ITEMS WITH KEY PARENT_ID = ITEMS-ID.
* increase level and exit loop if item has children
IF SY-SUBRC = 0.
START_TABIX = SY-TABIX.
APPEND V_TABIX TO TABIX_STACK. "level is no of recs in stack
V_PARENT_ID = ITEMS-PARENT_ID.
* set vline
V_TABIX = V_TABIX + 1.
READ TABLE ITEMS INDEX V_TABIX.
V_OFFSET = 2 + ( V_LEVEL - 1 ) * 3.
IF V_LEVEL > 0.
IF ITEMS-PARENT_ID = V_PARENT_ID_FOR_VLINE AND SY-SUBRC = 0.
V_VLINES_STRING+V_OFFSET = '|'.
ELSE.
V_VLINES_STRING+V_OFFSET = ' '.
ENDIF.
ENDIF.
EXIT.
ENDIF.
* at last - decrease level
AT LAST.
* clear vline
IF V_LEVEL > 1.
V_OFFSET = 2 + ( V_LEVEL - 2 ) * 3.
IF V_LEVEL = 1. V_OFFSET = 1. ENDIF.
V_VLINES_STRING+V_OFFSET = ' '.
ENDIF.
" next loop starts from parent index, not parent index + 1
" because of different parents level will decrease anyway
PERFORM READ_FROM_STACK CHANGING START_TABIX.
APPEND START_TABIX TO TABIX_STACK. "must return index to stack
ENDAT.
ENDLOOP.
DESCRIBE TABLE ITEMS.
IF START_TABIX > SY-TFILL OR V_ITEMS_COUNT >= SY-TFILL.
EXIT.
ENDIF.
ENDDO.
ENDFORM.

* form expand_collapse
FORM EXPAND_COLLAPSE USING VALUE(V_ID).
DATA: V_NO_MORE_ORPHANS,
ITEMS_TEMP LIKE ITEMS OCCURS 100 WITH HEADER LINE.
DELETE ITEMS_SHOW WHERE PARENT_ID = V_ID. "try to collapse
IF SY-SUBRC = 0. "succesfull first collapse
DO. "cascade collapse - delete 'orphans' that are left
REFRESH ITEMS_TEMP.
MOVE ITEMS_SHOW[] TO ITEMS_TEMP[].
SORT ITEMS_TEMP BY ID.
V_NO_MORE_ORPHANS = 'X'.
LOOP AT ITEMS_SHOW WHERE PARENT_ID NE ''.
READ TABLE ITEMS_TEMP WITH KEY ID = ITEMS_SHOW-PARENT_ID
BINARY SEARCH TRANSPORTING NO FIELDS.
IF SY-SUBRC NE 0. "no parent - it's an orphan
CLEAR V_NO_MORE_ORPHANS.
DELETE ITEMS_SHOW.
ENDIF.
ENDLOOP.
IF V_NO_MORE_ORPHANS = 'X'. EXIT. ENDIF.
ENDDO.
ITEMS_SHOW-SYMBOL = '+'.
MODIFY ITEMS_SHOW TRANSPORTING SYMBOL WHERE ID = V_ID.
ELSE. "unsuccessfull collapse - expand
ITEMS_SHOW-SYMBOL = '-'.
MODIFY ITEMS_SHOW TRANSPORTING SYMBOL WHERE ID = V_ID.
LOOP AT ITEMS WHERE PARENT_ID = V_ID. "show children
APPEND ITEMS TO ITEMS_SHOW.
ENDLOOP.
LOOP AT ITEMS_SHOW WHERE PARENT_ID = V_ID. "check grandchildren
READ TABLE ITEMS WITH KEY PARENT_ID = ITEMS_SHOW-ID.
IF SY-SUBRC = 0.
ITEMS_SHOW-SYMBOL = '+'.
ELSE.
ITEMS_SHOW-SYMBOL = ''.
ENDIF.
MODIFY ITEMS_SHOW.
ENDLOOP.
ENDIF.
ENDFORM.

* form append_item
FORM APPEND_ITEM USING VALUE(ID) VALUE(PARENT_ID) VALUE(TEXT).
ITEMS-ID = ID.
ITEMS-PARENT_ID = PARENT_ID.
ITEMS-TEXT = TEXT.
APPEND ITEMS.
ENDFORM.

* form read_from_stack
FORM READ_FROM_STACK CHANGING TABIX LIKE SY-TABIX.
DESCRIBE TABLE TABIX_STACK.
CHECK SY-TFILL NE 0.
READ TABLE TABIX_STACK INDEX SY-TFILL.
TABIX = TABIX_STACK.
DELETE TABIX_STACK INDEX SY-TFILL.
END FORM.