sidetomovefilter is a numeric filter that returns the numeric value of the side to move. Use
whiteto represent white to move; use
blackto represent black to move:
(In fact, the value of
1 and the value of
sidetomove filter is often used in the body of the echo filter to check that two positions have the same (or different) sides to move.
x is some position, then the side to move of
x:sidetomove. Thus, to check whether the side to move of
x is the same as the side to
move of the current position, use:
sidetomove == x:sidetomove
sidetomovefilter is used in castleecho.cql, chameleon.cql, enpassantecho.cql, flipverticalecho.cql, movedblackpieceecho.cql, underpromotionecho.cql, wcct7.cql.