Refactoring Example

Original Code

(worms game)
op = &(!x ? (!y ? upleft : (y == bottom ? lowleft : left)) :
(x == last ? (!y ? upright : (y == bottom ? lowright : right)) :
(!y ? upper : (y == bottom ? lower : normal))))[w->orientation];
What is going one here?

More Readable Representation

(Formatted as cascading if-else)
op = &(
!x ? (
    !y ? 
        upleft
    : ( y == bottom ? 
        lowleft
    :
        left
    )
) : ( x == last ? (
    !y ? 
        upright
    : ( y == bottom ? 
        lowright
    :
        right
    )
) : (
    !y ?
        upper
    : ( y == bottom ?
        lower
    :
        normal
    )
)
))[w->orientation];

Re-implementation

struct options *locations[3][3] = {
        {upleft,  upper,  upright},
        {left,    normal, right},
        {lowleft, lower, lowright},
};
int xlocation, ylocation;

if (x == 0)
        xlocation = 0;
else if (x == last)
        xlocation = 2;
else
        xlocation = 1;
if (y == 0)
        ylocation = 0;
else if (y == bottom)
        ylocation = 2;
else
        ylocation = 1;
op = &(locations[ylocation][xlocation])[w];

Other Implementation

(Suggested by Guy Steele)
op =
  &(        !y ? (!x ?  upleft : x!=last ?  upper :  upright ) :
     y!=bottom ? (!x ?    left : x!=last ? normal :    right ) :
                 (!x ? lowleft : x!=last ?  lower : lowright )
   )[w->orientation];

Creative Commons License  Last change: Monday, March 22, 2004 10:11 am
 Unless otherwise expressly stated, all original material on this page created by Diomidis Spinellis is licensed under a Creative Commons Attribution-Share Alike 3.0 Greece License.