from node import nullid, bin, hex

def readroots(repo):

    """Read phase roots from disk"""

    roots = [set() for i in allphases]

    roots[0].add(nullid)

    try:

        f = repo.sopener('phaseroots')

        try:

            for line in f:

                phase, nh = line.strip().split()

                roots[int(phase)].add(bin(nh))

        finally:

            f.close()

    except IOError:

        pass # default value are enough

    return roots

def writeroots(repo):

    """Write phase roots from disk"""

    f = repo.sopener('phaseroots', 'w', atomictemp=True)

    try:

        for phase, roots in enumerate(repo._phaseroots):

            for h in roots:

                f.write('%i %s\n' % (phase, hex(h)))

    finally:

        f.close()