[XBoard-devel] Parsing "++" and "+-+"

[h.g. muller]

How important is it to retain the possibility to parse "++" 
(White/BlackWins) and "+-+" (GameIsDrawn)?

I have a terrible problem there: Normally a "+" suffix on a move indicates 
check, but in Shogi it indicates a promotion. To reliably reognize 
promotions in Shogi I thus had to add the "+" suffix to the rules for 
moves. But the consequence of this is that the first "+" after a move is 
always eaten away, which is usually OK, as check indicators were ignored 
anyway. But when a mve is followed by "++" or "+-+", the rules for that no 
longer get to see the first "+", so they see just "+" or "-+". I could add 
a rule that parses the latter to GamesDrawn, but the solitary "+" is a 
problem. The current state is that the parsing of these symbols is broken.

The only way I see to get it back is very cumbersome: let the parser, in 
the rule for each move, set a global flag if it pased a "+" with the move, 
and make rules "+" and "-+" that return new symbols. Then make a wrapper 
for yylex(), which, on encountering these symbols, checks if the "+" flag 
was set, and if so, turns them into White/BlackWins or GameIsDrawn before 
returning them (and if not, just igore them). And before returning anything 
that is not some kind of move, clears the "+" flag. Is this really worth 
it? I thought that the compliant way to incicate checkmate is # or 1-0 or 0-1.

Of course the up-side of a wrapper around yylex() is that we could also 
make rules and smbols for "(" and ")", and let the wrapper take care of 
nesting to arbitrary depth.