//
// This function is the recursive search of groups for this
// implementation of the Group. The search proceeds building up
// a vector of already seen groups. Only new groups are considered,
// thereby avoiding loops.
//
boolean isMemberRecurse(Principal member, Vector<Group> alreadySeen) {
Enumeration<? extends Principal> e = members();
while (e.hasMoreElements()) {
boolean mem = false;
Principal p = (Principal) e.nextElement();
// if the member is in this collection, return true
if (p.equals(member)) {
return true;
} else if (p instanceof GroupImpl) {
//
// if not recurse if the group has not been checked already.
// Can call method in this package only if the object is an
// instance of this class. Otherwise call the method defined
// in the interface. (This can lead to a loop if a mixture of
// implementations form a loop, but we live with this improbable
// case rather than clutter the interface by forcing the
// implementation of this method.)
//
GroupImpl g = (GroupImpl) p;
alreadySeen.addElement(this);
if (!alreadySeen.contains(g)) mem = g.isMemberRecurse(member, alreadySeen);
} else if (p instanceof Group) {
Group g = (Group) p;
if (!alreadySeen.contains(g)) mem = g.isMember(member);
}
if (mem) return mem;
}
return false;
}
/**
* adds the specified member to the group.
*
* @param user The principal to add to the group.
* @return true if the member was added - false if the member could not be added.
*/
public boolean addMember(Principal user) {
if (groupMembers.contains(user)) return false;
// do not allow groups to be added to itself.
if (group.equals(user.toString())) throw new IllegalArgumentException();
groupMembers.addElement(user);
return true;
}
/**
* returns true if the passed principal is a member of the group.
*
* @param member The principal whose membership must be checked for.
* @return true if the principal is a member of this group, false otherwise
*/
public boolean isMember(Principal member) {
//
// if the member is part of the group (common case), return true.
// if not, recursively search depth first in the group looking for the
// principal.
//
if (groupMembers.contains(member)) {
return true;
} else {
Vector<Group> alreadySeen = new Vector<>(10);
return isMemberRecurse(member, alreadySeen);
}
}
/** returns the enumeration of the members in the group. */
public Enumeration<? extends Principal> members() {
return groupMembers.elements();
}
/**
* removes the specified member from the group.
*
* @param user The principal to remove from the group.
* @param true if the principal was removed false if the principal was not a member
*/
public boolean removeMember(Principal user) {
return groupMembers.removeElement(user);
}