Issues

• should getParent() return 0 or -1 when no parent was specified? 0 would be consistent with VobCoorder, but -1 would be more logical since then getCS(key) could be different from getCS(0, key).

  RESOLVED: 0. getCS(key) should be equivalent to getCS(0, key) to avoid horrible confusion.

Changes

Currently, VobMatcher has the methods

int add(int cs, Object key); 

int addSub(int into, int cs, Object key);

int getCS(Object key);

Object getKey(int cs);

The proposed changes are as follows:

• Name change: addSub --> add:

  int add(int into, int cs, Object key);
  

• add getCS with parent:

  /** Return the index of cs that was added into parent with key.
   */
  int getCS(int parent, Object key);
  

• add getParent and isAncestor:

  int getParent(int cs);
  
  /** Whether calling getParent(cs) recursively
   * (at least one time!) would eventually
   * return parent.
   */
  boolean isAncestor(int cs, int parent);
  

• Document that getCS returns -1 when no such cs exists.

Taken together, these changes make VobMatcher into a fully queriable implementation of a tree data structure with hash keys at each level of the tree.