💡📝H. G. Muller wrote on Thu, Aug 6, 2020 12:10 PM UTC:
The feature that allows you to dump the rules of the diagram as GAME code for creating rule-enforcing presets now seems to be at a stage where it could start to be useful. The code in the include file now would handle most CVs satisfactorily. Support of all the moves that can be described in XBetza and handled by the Interactive Diagram should be no problem, except for the Imitator. It now also tests for checkmate and stalemate, the 50-move rule, and repetitions. It can handle all the promotion rules that the Applet can be configured for. (I.e. piece-type-dependent zone depth, deferral, and promotion to captured pieces only.) Shuffling of pieces to get a start position also works.
There are some minor issues; testing for repetitions does ignore the virginity flags. The GAME-code implementation has a flag for every board square, but for any given CV most of the flags would be irrelevant, because the piece on that square (if any) would not have any initial moves defined on it. It is a bit of a chore to figure out which flags are relevant. This seems mostly a cosmetic problem, though; in virtual every variant the only relevant flags would be for castling and e.p. capture, and repetition loops in which you have those rights in the first occurrence, and then destroy them in the loop are very rare, and usually deserve to be draws anyway. Who cares if they are 2-fold or 3-fold repeats? Having the server declare a draw is a violation of FIDE rules anyway; these only say that the players can claim a draw in those situations.
Other things I have not implemented yet:
Testing the highlighted moves for legality; currently all pseudo-legal moves are highlighted.
Recognizing passing through check as illegal.
King baring as a winning condition.
Creation of e.p. rights by oblique lame leaps (Betza n on a W or F).
Imitators.
Crooked and circular pieces (Betza z and q).
All of that can be added through updating the GAME code in the include file, and would not affect operation of this Applet.
The feature that allows you to dump the rules of the diagram as GAME code for creating rule-enforcing presets now seems to be at a stage where it could start to be useful. The code in the include file now would handle most CVs satisfactorily. Support of all the moves that can be described in XBetza and handled by the Interactive Diagram should be no problem, except for the Imitator. It now also tests for checkmate and stalemate, the 50-move rule, and repetitions. It can handle all the promotion rules that the Applet can be configured for. (I.e. piece-type-dependent zone depth, deferral, and promotion to captured pieces only.) Shuffling of pieces to get a start position also works.
There are some minor issues; testing for repetitions does ignore the virginity flags. The GAME-code implementation has a flag for every board square, but for any given CV most of the flags would be irrelevant, because the piece on that square (if any) would not have any initial moves defined on it. It is a bit of a chore to figure out which flags are relevant. This seems mostly a cosmetic problem, though; in virtual every variant the only relevant flags would be for castling and e.p. capture, and repetition loops in which you have those rights in the first occurrence, and then destroy them in the loop are very rare, and usually deserve to be draws anyway. Who cares if they are 2-fold or 3-fold repeats? Having the server declare a draw is a violation of FIDE rules anyway; these only say that the players can claim a draw in those situations.
Other things I have not implemented yet:
All of that can be added through updating the GAME code in the include file, and would not affect operation of this Applet.