💡📝H. G. Muller wrote on Tue, Jul 21, 2020 12:55 PM UTC:
If the info on the first move on the sequence was always available, e.g. as firstmoves, firstorigin etc., and we would use the checkbox to suppress autoexecution of the move, it might be acceptably efficient to do the legality checking on all moves. That would certainly simplify the code a lot:
Post-Move:
set legal false;
set task 0; // specifies what subroutine genmoves should do with the generated moves
gosub genmoves firstmoved firstorigin; // compare all moves of the piece to thismove
if not legal:
die "Illegal move";
endif;
eval join "MOVE: " thismove; // make the move and its specified side effects
if unload:
drop unload dropsqr; // dropsquare and unload set by genmove for castlings
endif;
if locustsqr:
capture locustsqr; // locustsqr set by genmoves for castlings and e.p. captures
endif;
setflag firstdest; // moved piece is flagged as non-virgin
The need to store / restore has disappeared. The subroutine genmoves compares the moves of the moved piece in the pre-move position stringwise with thismove, and detects the cases where we are dealing with castling and regular e.p. capture. The implied side effects of these are then flagged by setting unload, dropsqr and locustsqr (which otherwise remain at false). Non-implied side effects are explicitly specified by the move, and thus already executed when we make thismove. So only these implied side effects have to be made afterwards (if the move proved pseudo-legal).
The subroutine genmoves would handle testing and setting of the e.p. info by itself; global variables ep and epsqrs would be involved in that.
Because the code is color-independent, it would probably be best to put it in a subroutine, and have both Post-Move sections just call that subroutine. Since it is also not dependent on the specifics of the variant, it could even be put in an include file. If the routine genmoves would be 'table-driven', it would also be variant-independent, and could also go into that include file. The data to drive it could then be supplied by variant-specific functions for each piece that would return an array describing the moves they could make. It would be the definitions of these funcions that would be generated by the Play-Test Applet, and would have to be copy-pasted to the corresponding preset. (To the Pre-Game section?)
I suppose the info about the first move of the sequence could be extracted 'by hand', by repeated explode, fist on a semicolon, then on a space to separate piece ID from move (already providing moved), and finally the move part on hyphen to get origin and dest.
If the info on the first move on the sequence was always available, e.g. as firstmoves, firstorigin etc., and we would use the checkbox to suppress autoexecution of the move, it might be acceptably efficient to do the legality checking on all moves. That would certainly simplify the code a lot:
Post-Move:
The need to store / restore has disappeared. The subroutine genmoves compares the moves of the moved piece in the pre-move position stringwise with thismove, and detects the cases where we are dealing with castling and regular e.p. capture. The implied side effects of these are then flagged by setting unload, dropsqr and locustsqr (which otherwise remain at false). Non-implied side effects are explicitly specified by the move, and thus already executed when we make thismove. So only these implied side effects have to be made afterwards (if the move proved pseudo-legal).
The subroutine genmoves would handle testing and setting of the e.p. info by itself; global variables ep and epsqrs would be involved in that.
Because the code is color-independent, it would probably be best to put it in a subroutine, and have both Post-Move sections just call that subroutine. Since it is also not dependent on the specifics of the variant, it could even be put in an include file. If the routine genmoves would be 'table-driven', it would also be variant-independent, and could also go into that include file. The data to drive it could then be supplied by variant-specific functions for each piece that would return an array describing the moves they could make. It would be the definitions of these funcions that would be generated by the Play-Test Applet, and would have to be copy-pasted to the corresponding preset. (To the Pre-Game section?)
I suppose the info about the first move of the sequence could be extracted 'by hand', by repeated explode, fist on a semicolon, then on a space to separate piece ID from move (already providing moved), and finally the move part on hyphen to get origin and dest.