ABAP Keyword Documentation → ABAP − Reference → ABAP Syntax → ABAP Statements → Operators and Expressions → Examples of Expression-Oriented Programming
Minesweeper
Expression-oriented implementation of a Minesweeper game.
Other versions:
7.31 | 7.40 | 7.54
Source Code
PROGRAM demo_minesweeper_740.
CLASS game DEFINITION.
PUBLIC SECTION.
METHODS:
constructor,
display.
PRIVATE SECTION.
TYPES:
BEGIN OF t_cell,
bomb TYPE abap_bool, " cell contains bomb y/n
bombs TYPE i, " # of neighboring bombs
state TYPE char1, " [h]idden, [v]isible, [f]lagged
END OF t_cell,
t_cells TYPE STANDARD TABLE OF t_cell WITH EMPTY KEY,
t_field TYPE STANDARD TABLE OF t_cells WITH EMPTY KEY.
DATA:
field TYPE t_field,
n TYPE i, " dimension of field
bombs TYPE i, " # of existing bombs
hidden TYPE i, " # of hidden cells
flags TYPE i, " # of flagged cells
moves TYPE i, " # of moves
over TYPE char1, " game over: [w]in, [d]ead
header TYPE string. " HTML header string
METHODS:
at_click FOR EVENT sapevent OF cl_abap_browser IMPORTING action,
detect IMPORTING VALUE(x) TYPE i VALUE(y) TYPE i.
ENDCLASS.
CLASS game IMPLEMENTATION.
METHOD constructor.
DATA(wh) = `width:13px;height:18px`.
header = replace(
occ = 0 sub = `@` with = `background-color:` val =
`<html><head><style type="text/css">` &&
`.bx{text-decoration:none;cursor:hand;` &&
wh && `} a{` && wh && `}` &&
`.hid{@#404080} .flg{@red} .bmb{@black}` &&
`.b0{@#e0e0e0} .b1{@lightblue} .b2{@lightgreen} .b3{@orange}` &&
`</style>` &&
`<script>function setloc(e){window.location=e;}</script>` &&
`</head><body scroll="no"><table border="0">` ) ##NO_TEXT.
DATA(size) = 10.
DATA(level) = 3.
cl_demo_input=>add_field( CHANGING field = size ).
cl_demo_input=>request( CHANGING field = level ).
" size: 2..32
n = nmax( val1 = 2 val2 = nmin( val1 = size val2 = 32 ) ).
" level: 1..5
level = nmax( val1 = 1 val2 = nmin( val1 = level val2 = 5 ) ).
DATA(threshold) = 100 - level * 10.
" place hidden bombs randomly
field = VALUE #(
LET r = cl_abap_random_int=>create( seed = CONV i( sy-uzeit )
min = 0
max = 99 ) IN
FOR i = 1 UNTIL i > n
( VALUE #( FOR j = 1 UNTIL j > n
( state = 'h'
bomb = COND #( WHEN r->get_next( ) > threshold
THEN 'X' ) ) ) ) ).
" compute neighboring-bombs count for each cell, and overall count
LOOP AT field ASSIGNING FIELD-SYMBOL(<cells>).
DATA(y) = sy-tabix.
LOOP AT <cells> ASSIGNING FIELD-SYMBOL(<cell>).
IF <cell>-bomb = 'X'.
bombs = bombs + 1.
ELSE.
DATA(x) = sy-tabix.
<cell>-bombs = REDUCE i(
INIT b = 0
FOR i = nmax( val1 = 1 val2 = y - 1 )
WHILE i <= nmin( val1 = y + 1 val2 = n )
FOR j = nmax( val1 = 1 val2 = x - 1 )
WHILE j <= nmin( val1 = x + 1 val2 = n )
LET <f> = field[ i ][ j ] IN
NEXT b = COND #( WHEN <f>-bomb = 'X' THEN b + 1 ELSE b ) ).
ENDIF.
ENDLOOP.
ENDLOOP.
hidden = n * n.
SET HANDLER at_click.
ENDMETHOD.
METHOD display.
cl_abap_browser=>show_html(
title = CONV cl_abap_browser=>title( sy-title )
size = COND #( WHEN n < 20 THEN cl_abap_browser=>small
ELSE cl_abap_browser=>medium )
format = cl_abap_browser=>portrait
context_menu = ' '
html_string =
REDUCE string(
INIT h = header
FOR y = 1 UNTIL y > n
NEXT h = h && |<tr{ COND #( WHEN over <> '' THEN
` onclick="setloc('sapevent:ovr');"` ) }>| &&
REDUCE string(
INIT k = ``
FOR x = 1 UNTIL x > n
LET c = field[ y ][ x ]
" CSS style (hid,flg,b0,...,b3) of cell
style = COND string(
WHEN over <> '' AND
c-bomb = 'X' " bomb
THEN `bmb`
WHEN c-state = 'f' " flagged
THEN `flg`
WHEN c-state = 'v' " visible
THEN |b{ nmin( val1 = c-bombs val2 = 3 ) }|
WHEN over <> '' " empty
THEN `b0`
ELSE `hid` ) " hidden
pos = |x{ x WIDTH = 2 ALIGN = RIGHT PAD = '0' }| &
|y{ y WIDTH = 2 ALIGN = RIGHT PAD = '0' }|
IN
NEXT k = |{ k }<td class={ style }| &&
COND #( WHEN c-state = 'v'
THEN |><a>{ c-bombs }</a>| " bombs value
ELSE " HTML events on cell (left: try; right: flag)
| oncontextmenu="setloc('sapevent:flg{ pos }');| &
|return false;"><a href="sapevent:try{ pos }">| &
|<div class="bx"></div></a>| )
&& `</td>` )
&& `</tr>` )
&& `</table>
`
&& COND #(
WHEN over = 'd' THEN `*** Bomb - Game over ***`
WHEN over = 'w' THEN |Finished in { moves } moves!| )
&& `</body></html>` ).
ENDMETHOD.
METHOD at_click.
IF over <> ''. " game is over, final click
cl_abap_browser=>close_browser( ).
LEAVE PROGRAM.
ENDIF.
moves = moves + 1.
DATA(x) = CONV i( action+4(2) ).
DATA(y) = CONV i( action+7(2) ).
ASSIGN field[ y ][ x ] TO FIELD-SYMBOL(<cell>).
IF action(3) = 'try'.
IF <cell>-bomb = 'X'.
over = 'd'. " hit bomb -> game over
ELSE.
detect( x = x y = y ).
ENDIF.
ELSE. " action(3) = 'flg'
IF <cell>-state = 'h'.
<cell>-state = 'f'. flags = flags + 1. hidden = hidden - 1.
ELSE.
<cell>-state = 'h'. flags = flags - 1. hidden = hidden + 1.
ENDIF.
ENDIF.
IF hidden = 0 AND flags = bombs .
over = 'w'. " all cells opened, all bombs found -> win
ENDIF.
display( ).
ENDMETHOD.
METHOD detect.
CHECK x >= 1 AND x <= n AND y >= 1 AND y <= n.
ASSIGN field[ y ][ x ] TO FIELD-SYMBOL(<cell>).
CASE <cell>-state.
WHEN 'v'. RETURN.
WHEN 'h'. hidden = hidden - 1.
WHEN 'f'. flags = flags - 1.
ENDCASE.
<cell>-state = 'v'.
CHECK <cell>-bombs = 0.
DATA(u) = y - 1.
DATA(d) = y + 1.
DATA(l) = x - 1.
DATA(r) = x + 1.
detect( y = u x = l ).
detect( y = u x = x ).
detect( y = u x = r ).
detect( y = y x = l ).
detect( y = y x = r ).
detect( y = d x = l ).
detect( y = d x = x ).
detect( y = d x = r ).
ENDMETHOD.
ENDCLASS.
START-OF-SELECTION.
NEW game( )->display( ).
Description
This example uses the implementation of a Minesweeper game to demonstrate expression-oriented ABAP programming (as introduced in Release 7.40). As a comparison, the program DEMO_MINESWEEPER_700 shows the same function implemented without expressions, mainly using language elements from Release 7.00 only.
To play the game, use the left and right mouse buttons to enter or select fields.