/**
* Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes
* visited by an expression in a source tree.
*
* <p>
*
* <p>The default implementation of this method assumes that an expression does no navigation
* other than the navigation done by evaluating its subexpressions, and that the subexpressions
* are evaluated in the same context as the containing expression. The method must be overridden
* for any expression where these assumptions do not hold. For example, implementations exist for
* AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for
* the doc(), document(), and collection() functions because they create a new navigation root.
* Implementations also exist for PathExpression and FilterExpression because they have
* subexpressions that are evaluated in a different context from the calling expression.
*
* @param pathMap the PathMap to which the expression should be added
* @param pathMapNodeSet the PathMapNodeSet to which the paths embodied in this expression should
* be added
* @return the pathMapNodeSet representing the points in the source document that are both
* reachable by this expression, and that represent possible results of this expression. For
* an expression that does navigation, it represents the end of the arc in the path map that
* describes the navigation route. For other expressions, it is the same as the input
* pathMapNode.
*/
public PathMap.PathMapNodeSet addToPathMap(
PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet) {
PathMap.PathMapNodeSet varPath = sequence.addToPathMap(pathMap, pathMapNodeSet);
pathMap.registerPathForVariable(this, varPath);
return action.addToPathMap(pathMap, pathMapNodeSet);
}