/**
* Mark an object or commit to start graph traversal from.
*
* <p>Callers are encouraged to use {@link RevWalk#parseAny(AnyObjectId)} instead of {@link
* RevWalk#lookupAny(AnyObjectId, int)}, as this method requires the object to be parsed before it
* can be added as a root for the traversal.
*
* <p>The method will automatically parse an unparsed object, but error handling may be more
* difficult for the application to explain why a RevObject is not actually valid. The object pool
* of this walker would also be 'poisoned' by the invalid RevObject.
*
* <p>This method will automatically call {@link RevWalk#markStart(RevCommit)} if passed RevCommit
* instance, or a RevTag that directly (or indirectly) references a RevCommit.
*
* @param o the object to start traversing from. The object passed must be from this same revision
* walker.
* @throws MissingObjectException the object supplied is not available from the object database.
* This usually indicates the supplied object is invalid, but the reference was constructed
* during an earlier invocation to {@link RevWalk#lookupAny(AnyObjectId, int)}.
* @throws IncorrectObjectTypeException the object was not parsed yet and it was discovered during
* parsing that it is not actually the type of the instance passed in. This usually indicates
* the caller used the wrong type in a {@link RevWalk#lookupAny(AnyObjectId, int)} call.
* @throws IOException a pack file or loose object could not be read.
*/
public void markStart(RevObject o)
throws MissingObjectException, IncorrectObjectTypeException, IOException {
while (o instanceof RevTag) {
addObject(o);
o = ((RevTag) o).getObject();
parseHeaders(o);
}
if (o instanceof RevCommit) super.markStart((RevCommit) o);
else addObject(o);
}
