path: root/Lib/mhlib.py

# MH interface -- purely object-oriented (well, almost)
#
# Executive summary:
#
# import mhlib
#
# mh = mhlib.MH()         # use default mailbox directory and profile
# mh = mhlib.MH(mailbox)  # override mailbox location (default from profile)
# mh = mhlib.MH(mailbox, profile) # override mailbox and profile
#
# mh.error(format, ...)   # print error message -- can be overridden
# s = mh.getprofile(key)  # profile entry (None if not set)
# path = mh.getpath()     # mailbox pathname
# name = mh.getcontext()  # name of current folder
# mh.setcontext(name)     # set name of current folder
#
# list = mh.listfolders() # names of top-level folders
# list = mh.listallfolders() # names of all folders, including subfolders
# list = mh.listsubfolders(name) # direct subfolders of given folder
# list = mh.listallsubfolders(name) # all subfolders of given folder
#
# mh.makefolder(name)     # create new folder
# mh.deletefolder(name)   # delete folder -- must have no subfolders
#
# f = mh.openfolder(name) # new open folder object
#
# f.error(format, ...)    # same as mh.error(format, ...)
# path = f.getfullname()  # folder's full pathname
# path = f.getsequencesfilename() # full pathname of folder's sequences file
# path = f.getmessagefilename(n)  # full pathname of message n in folder
#
# list = f.listmessages() # list of messages in folder (as numbers)
# n = f.getcurrent()      # get current message
# f.setcurrent(n)         # set current message
# list = f.parsesequence(seq)     # parse msgs syntax into list of messages
# n = f.getlast()         # get last message (0 if no messagse)
# f.setlast(n)            # set last message (internal use only)
#
# dict = f.getsequences() # dictionary of sequences in folder {name: list}
# f.putsequences(dict)    # write sequences back to folder
#
# f.removemessages(list)  # remove messages in list from folder
# f.refilemessages(list, tofolder) # move messages in list to other folder
# f.movemessage(n, tofolder, ton)  # move one message to a given destination
# f.copymessage(n, tofolder, ton)  # copy one message to a given destination
#
# m = f.openmessage(n)    # new open message object (costs a file descriptor)
# m is a derived class of mimetools.Message(rfc822.Message), with:
# s = m.getheadertext()   # text of message's headers
# s = m.getheadertext(pred) # text of message's headers, filtered by pred
# s = m.getbodytext()     # text of message's body, decoded
# s = m.getbodytext(0)    # text of message's body, not decoded
#
# XXX To do, functionality:
# - annotate messages
# - create, send messages
#
# XXX To do, organization:
# - move IntSet to separate file
# - move most Message functionality to module mimetools


# Customizable defaults

MH_PROFILE = '~/.mh_profile'
PATH = '~/Mail'
MH_SEQUENCES = '.mh_sequences'
FOLDER_PROTECT = 0700


# Imported modules

import os
import sys
from stat import ST_NLINK
import regex
import string
import mimetools
import multifile
import shutil
from bisect import bisect


# Exported constants

Error = 'mhlib.Error'


# Class representing a particular collection of folders.
# Optional constructor arguments are the pathname for the directory
# containing the collection, and the MH profile to use.
# If either is omitted or empty a default is used; the default
# directory is taken from the MH profile if it is specified there.

class MH:

    # Constructor
    def __init__(self, path = None, profile = None):
	if not profile: profile = MH_PROFILE
	self.profile = os.path.expanduser(profile)
	if not path: path = self.getprofile('Path')
	if not path: path = PATH
	if not os.path.isabs(path) and path[0] != '~':
	    path = os.path.join('~', path)
	path = os.path.expanduser(path)
	if not os.path.isdir(path): raise Error, 'MH() path not found'
	self.path = path

    # String representation
    def __repr__(self):
	return 'MH(%s, %s)' % (`self.path`, `self.profile`)

    # Routine to print an error.  May be overridden by a derived class
    def error(self, msg, *args):
	sys.stderr.write('MH error: %s\n' % (msg % args))

    # Return a profile entry, None if not found
    def getprofile(self, key):
	return pickline(self.profile, key)

    # Return the path (the name of the collection's directory)
    def getpath(self):
	return self.path

    # Return the name of the current folder
    def getcontext(self):
	context = pickline(os.path.join(self.getpath(), 'context'),
		  'Current-Folder')
	if not context: context = 'inbox'
	return context

    # Set the name of the current folder
    def setcontext(self, context):
	fn = os.path.join(self.getpath(), 'context')
	f = open(fn, "w")
	f.write("Current-Folder: %s\n" % context)
	f.close()

    # Return the names of the top-level folders
    def listfolders(self):
	folders = []
	path = self.getpath()
	for name in os.listdir(path):
	    fullname = os.path.join(path, name)
	    if os.path.isdir(fullname):
		folders.append(name)
	folders.sort()
	return folders

    # Return the names of the subfolders in a given folder
    # (prefixed with the given folder name)
    def listsubfolders(self, name):
	fullname = os.path.join(self.path, name)
	# Get the link count so we can avoid listing folders
	# that have no subfolders.
	st = os.stat(fullname)
	nlinks = st[ST_NLINK]
	if nlinks <= 2:
	    return []
	subfolders = []
	subnames = os.listdir(fullname)
	for subname in subnames:
	    fullsubname = os.path.join(fullname, subname)
	    if os.path.isdir(fullsubname):
		name_subname = os.path.join(name, subname)
		subfolders.append(name_subname)
		# Stop looking for subfolders when
		# we've seen them all
		nlinks = nlinks - 1
		if nlinks <= 2:
		    break
	subfolders.sort()
	return subfolders

    # Return the names of all folders, including subfolders, recursively
    def listallfolders(self):
	return self.listallsubfolders('')

    # Return the names of subfolders in a given folder, recursively
    def listallsubfolders(self, name):
	fullname = os.path.join(self.path, name)
	# Get the link count so we can avoid listing folders
	# that have no subfolders.
	st = os.stat(fullname)
	nlinks = st[ST_NLINK]
	if nlinks <= 2:
	    return []
	subfolders = []
	subnames = os.listdir(fullname)
	for subname in subnames:
	    if subname[0] == ',' or isnumeric(subname): continue
	    fullsubname = os.path.join(fullname, subname)
	    if os.path.isdir(fullsubname):
		name_subname = os.path.join(name, subname)
		subfolders.append(name_subname)
		if not os.path.islink(fullsubname):
		    subsubfolders = self.listallsubfolders(
			      name_subname)
		    subfolders = subfolders + subsubfolders
		# Stop looking for subfolders when
		# we've seen them all
		nlinks = nlinks - 1
		if nlinks <= 2:
		    break
	subfolders.sort()
	return subfolders

    # Return a new Folder object for the named folder
    def openfolder(self, name):
	return Folder(self, name)

    # Create a new folder.  This raises os.error if the folder
    # cannot be created
    def makefolder(self, name):
	protect = pickline(self.profile, 'Folder-Protect')
	if protect and isnumeric(protect):
	    mode = string.atoi(protect, 8)
	else:
	    mode = FOLDER_PROTECT
	os.mkdir(os.path.join(self.getpath(), name), mode)

    # Delete a folder.  This removes files in the folder but not
    # subdirectories.  If deleting the folder itself fails it
    # raises os.error
    def deletefolder(self, name):
	fullname = os.path.join(self.getpath(), name)
	for subname in os.listdir(fullname):
	    fullsubname = os.path.join(fullname, subname)
	    try:
		os.unlink(fullsubname)
	    except os.error:
		self.error('%s not deleted, continuing...' %
			  fullsubname)
	os.rmdir(fullname)


# Class representing a particular folder

numericprog = regex.compile('^[1-9][0-9]*$')
def isnumeric(str):
    return numericprog.match(str) >= 0

class Folder:

    # Constructor
    def __init__(self, mh, name):
	self.mh = mh
	self.name = name
	if not os.path.isdir(self.getfullname()):
	    raise Error, 'no folder %s' % name

    # String representation
    def __repr__(self):
	return 'Folder(%s, %s)' % (`self.mh`, `self.name`)

    # Error message handler
    def error(self, *args):
	apply(self.mh.error, args)

    # Return the full pathname of the folder
    def getfullname(self):
	return os.path.join(self.mh.path, self.name)

    # Return the full pathname of the folder's sequences file
    def getsequencesfilename(self):
	return os.path.join(self.getfullname(), MH_SEQUENCES)

    # Return the full pathname of a message in the folder
    def getmessagefilename(self, n):
	return os.path.join(self.getfullname(), str(n))

    # Return list of direct subfolders
    def listsubfolders(self):
	return self.mh.listsubfolders(self.name)

    # Return list of all subfolders
    def listallsubfolders(self):
	return self.mh.listallsubfolders(self.name)

    # Return the list of messages currently present in the folder.
    # As a side effect, set self.last to the last message (or 0)
    def listmessages(self):
	messages = []
	match = numericprog.match
	append = messages.append
	for name in os.listdir(self.getfullname()):
	    if match(name) >= 0:
		append(name)
	messages = map(string.atoi, messages)
	messages.sort()
	if messages:
	    self.last = messages[-1]
	else:
	    self.last = 0
	return messages

    # Return the set of sequences for the folder
    def getsequences(self):
	sequences = {}
	fullname = self.getsequencesfilename()
	try:
	    f = open(fullname, 'r')
	except IOError:
	    return sequences
	while 1:
	    line = f.readline()
	    if not line: break
	    fields = string.splitfields(line, ':')
	    if len(fields) <> 2:
		self.error('bad sequence in %s: %s' %
			  (fullname, string.strip(line)))
	    key = string.strip(fields[0])
	    value = IntSet(string.strip(fields[1]), ' ').tolist()
	    sequences[key] = value
	return sequences

    # Write the set of sequences back to the folder
    def putsequences(self, sequences):
	fullname = self.getsequencesfilename()
	f = None
	for key in sequences.keys():
	    s = IntSet('', ' ')
	    s.fromlist(sequences[key])
	    if not f: f = open(fullname, 'w')
	    f.write('%s: %s\n' % (key, s.tostring()))
	if not f:
	    try:
		os.unlink(fullname)
	    except os.error:
		pass
	else:
	    f.close()

    # Return the current message.  Raise KeyError when there is none
    def getcurrent(self):
	seqs = self.getsequences()
	try:
	    return max(seqs['cur'])
	except (ValueError, KeyError):
	    raise Error, "no cur message"

    # Set the current message
    def setcurrent(self, n):
	updateline(self.getsequencesfilename(), 'cur', str(n), 0)

    # Parse an MH sequence specification into a message list.
    # Attempt to mimic mh-sequence(5) as close as possible.
    # Also attempt to mimic observed behavior regarding which
    # conditions cause which error messages
    def parsesequence(self, seq):
	# XXX Still not complete (see mh-format(5)).
	# Missing are:
	# - 'prev', 'next' as count
	# - Sequence-Negation option
	all = self.listmessages()
	# Observed behavior: test for empty folder is done first
	if not all:
	    raise Error, "no messages in %s" % self.name
	# Common case first: all is frequently the default
	if seq == 'all':
	    return all
	# Test for X:Y before X-Y because 'seq:-n' matches both
	i = string.find(seq, ':')
	if i >= 0:
	    head, dir, tail = seq[:i], '', seq[i+1:]
	    if tail[:1] in '-+':
		dir, tail = tail[:1], tail[1:]
	    if not isnumeric(tail):
		raise Error, "bad message list %s" % seq
	    try:
		count = string.atoi(tail)
	    except (ValueError, OverflowError):
		# Can't use sys.maxint because of i+count below
		count = len(all)
	    try:
		anchor = self._parseindex(head, all)
	    except Error, msg:
		seqs = self.getsequences()
		if not seqs.has_key(head):
		    if not msg:
			msg = "bad message list %s" % seq
		    raise Error, msg, sys.exc_info()[2]
		msgs = seqs[head]
		if not msgs:
		    raise Error, "sequence %s empty" % head
		if dir == '-':
		    return msgs[-count:]
		else:
		    return msgs[:count]
	    else:
		if not dir:
		    if head in ('prev', 'last'):
			dir = '-'
		if dir == '-':
		    i = bisect(all, anchor)
		    return all[max(0, i-count):i]
		else:
		    i = bisect(all, anchor-1)
		    return all[i:i+count]
	# Test for X-Y next
	i = string.find(seq, '-')
	if i >= 0:
	    begin = self._parseindex(seq[:i], all)
	    end = self._parseindex(seq[i+1:], all)
	    i = bisect(all, begin-1)
	    j = bisect(all, end)
	    r = all[i:j]
	    if not r:
		raise Error, "bad message list %s" % seq
	    return r
	# Neither X:Y nor X-Y; must be a number or a (pseudo-)sequence
	try:
	    n = self._parseindex(seq, all)
	except Error, msg:
	    seqs = self.getsequences()
	    if not seqs.has_key(seq):
		if not msg:
		    msg = "bad message list %s" % seq
		raise Error, msg
	    return seqs[seq]
	else:
	    if n not in all:
		if isnumeric(seq):
		    raise Error, "message %d doesn't exist" % n
		else:
		    raise Error, "no %s message" % seq
	    else:
		return [n]

    # Internal: parse a message number (or cur, first, etc.)
    def _parseindex(self, seq, all):
	if isnumeric(seq):
	    try:
		return string.atoi(seq)
	    except (OverflowError, ValueError):
		return sys.maxint
	if seq in ('cur', '.'):
	    return self.getcurrent()
	if seq == 'first':
	    return all[0]
	if seq == 'last':
	    return all[-1]
	if seq == 'next':
	    n = self.getcurrent()
	    i = bisect(all, n)
	    try:
		return all[i]
	    except IndexError:
		raise Error, "no next message"
	if seq == 'prev':
	    n = self.getcurrent()
	    i = bisect(all, n-1)
	    if i == 0:
		raise Error, "no prev message"
	    try:
		return all[i-1]
	    except IndexError:
		raise Error, "no prev message"
	raise Error, None

    # Open a message -- returns a Message object
    def openmessage(self, n):
	return Message(self, n)

    # Remove one or more messages -- may raise os.error
    def removemessages(self, list):
	errors = []
	deleted = []
	for n in list:
	    path = self.getmessagefilename(n)
	    commapath = self.getmessagefilename(',' + str(n))
	    try:
		os.unlink(commapath)
	    except os.error:
		pass
	    try:
		os.rename(path, commapath)
	    except os.error, msg:
		errors.append(msg)
	    else:
		deleted.append(n)
	if deleted:
	    self.removefromallsequences(deleted)
	if errors:
	    if len(errors) == 1:
		raise os.error, errors[0]
	    else:
		raise os.error, ('multiple errors:', errors)

    # Refile one or more messages -- may raise os.error.
    # 'tofolder' is an open folder object
    def refilemessages(self, list, tofolder, keepsequences=0):
	errors = []
	refiled = {}
	for n in list:
	    ton = tofolder.getlast() + 1
	    path = self.getmessagefilename(n)
	    topath = tofolder.getmessagefilename(ton)
	    try:
		os.rename(path, topath)
	    except os.error:
		# Try copying
		try:
		    shutil.copy2(path, topath)
		    os.unlink(path)
		except (IOError, os.error), msg:
		    errors.append(msg)
		    try:
			os.unlink(topath)
		    except os.error:
			pass
		    continue
	    tofolder.setlast(ton)
	    refiled[n] = ton
	if refiled:
	    if keepsequences:
		tofolder._copysequences(self, refiled.items())
	    self.removefromallsequences(refiled.keys())
	if errors:
	    if len(errors) == 1:
		raise os.error, errors[0]
	    else:
		raise os.error, ('multiple errors:', errors)

    # Helper for refilemessages() to copy sequences
    def _copysequences(self, fromfolder, refileditems):
	fromsequences = fromfolder.getsequences()
	tosequences = self.getsequences()
	changed = 0
	for name, seq in fromsequences.items():
	    try:
		toseq = tosequences[name]
		new = 0
	    except:
		toseq = []
		new = 1
	    for fromn, ton in refileditems:
		if fromn in seq:
		    toseq.append(ton)
		    changed = 1
	    if new and toseq:
		tosequences[name] = toseq
	if changed:
	    self.putsequences(tosequences)

    # Move one message over a specific destination message,
    # which may or may not already exist.
    def movemessage(self, n, tofolder, ton):
	path = self.getmessagefilename(n)
	# Open it to check that it exists
	f = open(path)
	f.close()
	del f
	topath = tofolder.getmessagefilename(ton)
	backuptopath = tofolder.getmessagefilename(',%d' % ton)
	try:
	    os.rename(topath, backuptopath)
	except os.error:
	    pass
	try:
	    os.rename(path, topath)
	except os.error:
	    # Try copying
	    ok = 0
	    try:
		tofolder.setlast(None)
		shutil.copy2(path, topath)
		ok = 1
	    finally:
		if not ok:
		    try:
			os.unlink(topath)
		    except os.error:
			pass
	    os.unlink(path)
	self.removefromallsequences([n])

    # Copy one message over a specific destination message,
    # which may or may not already exist.
    def copymessage(self, n, tofolder, ton):
	path = self.getmessagefilename(n)
	# Open it to check that it exists
	f = open(path)
	f.close()
	del f
	topath = tofolder.getmessagefilename(ton)
	backuptopath = tofolder.getmessagefilename(',%d' % ton)
	try:
	    os.rename(topath, backuptopath)
	except os.error:
	    pass
	ok = 0
	try:
	    tofolder.setlast(None)
	    shutil.copy2(path, topath)
	    ok = 1
	finally:
	    if not ok:
		try:
		    os.unlink(topath)
		except os.error:
		    pass

    # Create a message, with text from the open file txt.
    def createmessage(self, n, txt):
	path = self.getmessagefilename(n)
	backuppath = self.getmessagefilename(',%d' % n)
	try:
	    os.rename(path, backuppath)
	except os.error:
	    pass
	ok = 0
	BUFSIZE = 16*1024
	try:
	    f = open(path, "w")
	    while 1:
		buf = txt.read(BUFSIZE)
		if not buf:
		    break
		f.write(buf)
	    f.close()
	    ok = 1
	finally:
	    if not ok:
		try:
		    os.unlink(path)
		except os.error:
		    pass

    # Remove one or more messages from all sequeuces (including last)
    # -- but not from 'cur'!!!
    def removefromallsequences(self, list):
	if hasattr(self, 'last') and self.last in list:
	    del self.last
	sequences = self.getsequences()
	changed = 0
	for name, seq in sequences.items():
	    if name == 'cur':
		continue
	    for n in list:
		if n in seq:
		    seq.remove(n)
		    changed = 1
		    if not seq:
			del sequences[name]
	if changed:
	    self.putsequences(sequences)

    # Return the last message number
    def getlast(self):
	if not hasattr(self, 'last'):
	    messages = self.listmessages()
	return self.last

    # Set the last message number
    def setlast(self, last):
	if last is None:
	    if hasattr(self, 'last'):
		del self.last
	else:
	    self.last = last

class Message(mimetools.Message):

    # Constructor
    def __init__(self, f, n, fp = None):
	self.folder = f
	self.number = n
	if not fp:
	    path = f.getmessagefilename(n)
	    fp = open(path, 'r')
	mimetools.Message.__init__(self, fp)

    # String representation
    def __repr__(self):
	return 'Message(%s, %s)' % (repr(self.folder), self.number)

    # Return the message's header text as a string.  If an
    # argument is specified, it is used as a filter predicate to
    # decide which headers to return (its argument is the header
    # name converted to lower case).
    def getheadertext(self, pred = None):
	if not pred:
	    return string.joinfields(self.headers, '')
	headers = []
	hit = 0
	for line in self.headers:
	    if line[0] not in string.whitespace:
		i = string.find(line, ':')
		if i > 0:
		    hit = pred(string.lower(line[:i]))
	    if hit: headers.append(line)
	return string.joinfields(headers, '')

    # Return the message's body text as string.  This undoes a
    # Content-Transfer-Encoding, but does not interpret other MIME
    # features (e.g. multipart messages).  To suppress to
    # decoding, pass a 0 as argument
    def getbodytext(self, decode = 1):
	self.fp.seek(self.startofbody)
	encoding = self.getencoding()
	if not decode or encoding in ('7bit', '8bit', 'binary'):
	    return self.fp.read()
	from StringIO import StringIO
	output = StringIO()
	mimetools.decode(self.fp, output, encoding)
	return output.getvalue()

    # Only for multipart messages: return the message's body as a
    # list of SubMessage objects.  Each submessage object behaves
    # (almost) as a Message object.
    def getbodyparts(self):
	if self.getmaintype() != 'multipart':
	    raise Error, 'Content-Type is not multipart/*'
	bdry = self.getparam('boundary')
	if not bdry:
	    raise Error, 'multipart/* without boundary param'
	self.fp.seek(self.startofbody)
	mf = multifile.MultiFile(self.fp)
	mf.push(bdry)
	parts = []
	while mf.next():
	    n = str(self.number) + '.' + `1 + len(parts)`
	    part = SubMessage(self.folder, n, mf)
	    parts.append(part)
	mf.pop()
	return parts

    # Return body, either a string or a list of messages
    def getbody(self):
	if self.getmaintype() == 'multipart':
	    return self.getbodyparts()
	else:
	    return self.getbodytext()


class SubMessage(Message):

    # Constructor
    def __init__(self, f, n, fp):
	Message.__init__(self, f, n, fp)
	if self.getmaintype() == 'multipart':
	    self.body = Message.getbodyparts(self)
	else:
	    self.body = Message.getbodytext(self)
	    # XXX If this is big, should remember file pointers

    # String representation
    def __repr__(self):
	f, n, fp = self.folder, self.number, self.fp
	return 'SubMessage(%s, %s, %s)' % (f, n, fp)

    def getbodytext(self):
	if type(self.body) == type(''):
	    return self.body

    def getbodyparts(self):
	if type(self.body) == type([]):
	    return self.body

    def getbody(self):
	return self.body


# Class implementing sets of integers.
#
# This is an efficient representation for sets consisting of several
# continuous ranges, e.g. 1-100,200-400,402-1000 is represented
# internally as a list of three pairs: [(1,100), (200,400),
# (402,1000)].  The internal representation is always kept normalized.
#
# The constructor has up to three arguments:
# - the string used to initialize the set (default ''),
# - the separator between ranges (default ',')
# - the separator between begin and end of a range (default '-')
# The separators may be regular expressions and should be different.
#
# The tostring() function yields a string that can be passed to another
# IntSet constructor; __repr__() is a valid IntSet constructor itself.
#
# XXX The default begin/end separator means that negative numbers are
#     not supported very well.
#
# XXX There are currently no operations to remove set elements.

class IntSet:

    def __init__(self, data = None, sep = ',', rng = '-'):
	self.pairs = []
	self.sep = sep
	self.rng = rng
	if data: self.fromstring(data)

    def reset(self):
	self.pairs = []

    def __cmp__(self, other):
	return cmp(self.pairs, other.pairs)

    def __hash__(self):
	return hash(self.pairs)

    def __repr__(self):
	return 'IntSet(%s, %s, %s)' % (`self.tostring()`,
		  `self.sep`, `self.rng`)

    def normalize(self):
	self.pairs.sort()
	i = 1
	while i < len(self.pairs):
	    alo, ahi = self.pairs[i-1]
	    blo, bhi = self.pairs[i]
	    if ahi >= blo-1:
		self.pairs[i-1:i+1] = [(alo, max(ahi, bhi))]
	    else:
		i = i+1

    def tostring(self):
	s = ''
	for lo, hi in self.pairs:
	    if lo == hi: t = `lo`
	    else: t = `lo` + self.rng + `hi`
	    if s: s = s + (self.sep + t)
	    else: s = t
	return s

    def tolist(self):
	l = []
	for lo, hi in self.pairs:
	    m = range(lo, hi+1)
	    l = l + m
	return l

    def fromlist(self, list):
	for i in list:
	    self.append(i)

    def clone(self):
	new = IntSet()
	new.pairs = self.pairs[:]
	return new

    def min(self):
	return self.pairs[0][0]

    def max(self):
	return self.pairs[-1][-1]

    def contains(self, x):
	for lo, hi in self.pairs:
	    if lo <= x <= hi: return 1
	return 0

    def append(self, x):
	for i in range(len(self.pairs)):
	    lo, hi = self.pairs[i]
	    if x < lo: # Need to insert before
		if x+1 == lo:
		    self.pairs[i] = (x, hi)
		else:
		    self.pairs.insert(i, (x, x))
		if i > 0 and x-1 == self.pairs[i-1][1]:
		    # Merge with previous
		    self.pairs[i-1:i+1] = [
			    (self.pairs[i-1][0],
			     self.pairs[i][1])
			  ]
		return
	    if x <= hi: # Already in set
		return
	i = len(self.pairs) - 1
	if i >= 0:
	    lo, hi = self.pairs[i]
	    if x-1 == hi:
		self.pairs[i] = lo, x
		return
	self.pairs.append((x, x))

    def addpair(self, xlo, xhi):
	if xlo > xhi: return
	self.pairs.append((xlo, xhi))
	self.normalize()

    def fromstring(self, data):
	import string, regsub
	new = []
	for part in regsub.split(data, self.sep):
	    list = []
	    for subp in regsub.split(part, self.rng):
		s = string.strip(subp)
		list.append(string.atoi(s))
	    if len(list) == 1:
		new.append((list[0], list[0]))
	    elif len(list) == 2 and list[0] <= list[1]:
		new.append((list[0], list[1]))
	    else:
		raise ValueError, 'bad data passed to IntSet'
	self.pairs = self.pairs + new
	self.normalize()


# Subroutines to read/write entries in .mh_profile and .mh_sequences

def pickline(file, key, casefold = 1):
    try:
	f = open(file, 'r')
    except IOError:
	return None
    pat = key + ':'
    if casefold:
	prog = regex.compile(pat, regex.casefold)
    else:
	prog = regex.compile(pat)
    while 1:
	line = f.readline()
	if not line: break
	if prog.match(line) >= 0:
	    text = line[len(key)+1:]
	    while 1:
		line = f.readline()
		if not line or line[0] not in string.whitespace:
		    break
		text = text + line
	    return string.strip(text)
    return None

def updateline(file, key, value, casefold = 1):
    try:
	f = open(file, 'r')
	lines = f.readlines()
	f.close()
    except IOError:
	lines = []
    pat = key + ':\(.*\)\n'
    if casefold:
	prog = regex.compile(pat, regex.casefold)
    else:
	prog = regex.compile(pat)
    if value is None:
	newline = None
    else:
	newline = '%s: %s\n' % (key, value)
    for i in range(len(lines)):
	line = lines[i]
	if prog.match(line) == len(line):
	    if newline is None:
		del lines[i]
	    else:
		lines[i] = newline
	    break
    else:
	if newline is not None:
	    lines.append(newline)
    tempfile = file + "~"
    f = open(tempfile, 'w')
    for line in lines:
	f.write(line)
    f.close()
    os.rename(tempfile, file)


# Test program

def test():
    global mh, f
    os.system('rm -rf $HOME/Mail/@test')
    mh = MH()
    def do(s): print s; print eval(s)
    do('mh.listfolders()')
    do('mh.listallfolders()')
    testfolders = ['@test', '@test/test1', '@test/test2',
		   '@test/test1/test11', '@test/test1/test12',
		   '@test/test1/test11/test111']
    for t in testfolders: do('mh.makefolder(%s)' % `t`)
    do('mh.listsubfolders(\'@test\')')
    do('mh.listallsubfolders(\'@test\')')
    f = mh.openfolder('@test')
    do('f.listsubfolders()')
    do('f.listallsubfolders()')
    do('f.getsequences()')
    seqs = f.getsequences()
    seqs['foo'] = IntSet('1-10 12-20', ' ').tolist()
    print seqs
    f.putsequences(seqs)
    do('f.getsequences()')
    testfolders.reverse()
    for t in testfolders: do('mh.deletefolder(%s)' % `t`)
    do('mh.getcontext()')
    context = mh.getcontext()
    f = mh.openfolder(context)
    do('f.getcurrent()')
    for seq in ['first', 'last', 'cur', '.', 'prev', 'next',
		'first:3', 'last:3', 'cur:3', 'cur:-3',
		'prev:3', 'next:3',
		'1:3', '1:-3', '100:3', '100:-3', '10000:3', '10000:-3',
		'all']:
	try:
	    do('f.parsesequence(%s)' % `seq`)
	except Error, msg:
	    print "Error:", msg
	stuff = os.popen("pick %s 2>/dev/null" % `seq`).read()
	list = map(string.atoi, string.split(stuff))
	print list, "<-- pick"
    do('f.listmessages()')


if __name__ == '__main__':
    test()