child

The child filter returns the primary child of the current position. Thus,

  x=child

will set the variable x to the primary child of the current position (if the current position is a terminal position, then the assignment will not match and x will not be modified). Recall that if variations is not set in the CQL header, then the primary child of the current position is the same as the child, as any position has at most one child.

If the child filter is followed by a numeric filter enclosed in parentheses, then the the child with index i is returned, where i is the value of that numeric filter:

  x=child(1)

If no such child exists, the filter will not match. Thus child without an argument is the same as child(0).

Getting the number of children

The following computes the number of childen in a position:

  countmoves ――