zeroinstall/injector/model.py

   1 """In-memory representation of interfaces and other data structures.
   2
   3 The objects in this module are used to build a representation of an XML interface
   4 file in memory.
   5
   6 @see: L{reader} constructs these data-structures
   7 @see: U{http://0install.net/interface-spec.html} description of the domain model
   8
   9 @var defaults: Default values for the 'default' attribute for <environment> bindings of
  10 well-known variables.
  11 """
  12
  13 # Copyright (C) 2009, Thomas Leonard
  14 # See the README file for details, or visit http://0install.net.
  15
  16 from zeroinstall import _
  17 import os, re, locale
  18 from logging import info, debug, warn
  19 from zeroinstall import SafeException, version
  20 from zeroinstall.injector.namespaces import XMLNS_IFACE
  21 from zeroinstall.injector import qdom
  22
  23 # Element names for bindings in feed files
  24 binding_names = frozenset(['environment', 'overlay', 'executable-in-path', 'executable-in-var'])
  25
  26 network_offline = 'off-line'
  27 network_minimal = 'minimal'
  28 network_full = 'full'
  29 network_levels = (network_offline, network_minimal, network_full)
  30
  31 stability_levels = {}   # Name -> Stability
  32
  33 defaults = {
  34         'PATH': '/bin:/usr/bin',
  35         'XDG_CONFIG_DIRS': '/etc/xdg',
  36         'XDG_DATA_DIRS': '/usr/local/share:/usr/share',
  37 }
  38
  39 class InvalidInterface(SafeException):
  40         """Raised when parsing an invalid feed."""
  41         feed_url = None
  42
  43         def __init__(self, message, ex = None):
  44                 if ex:
  45                         try:
  46                                 message += "\n\n(exact error: %s)" % ex
  47                         except:
  48                                 # Some Python messages have type str but contain UTF-8 sequences.
  49                                 # (e.g. IOException). Adding these to a Unicode 'message' (e.g.
  50                                 # after gettext translation) will cause an error.
  51                                 import codecs
  52                                 decoder = codecs.lookup('utf-8')
  53                                 decex = decoder.decode(str(ex), errors = 'replace')[0]
  54                                 message += "\n\n(exact error: %s)" % decex
  55
  56                 SafeException.__init__(self, message)
  57
  58         def __unicode__(self):
  59                 if hasattr(SafeException, '__unicode__'):
  60                         # Python >= 2.6
  61                         if self.feed_url:
  62                                 return _('%s [%s]') % (SafeException.__unicode__(self), self.feed_url)
  63                         return SafeException.__unicode__(self)
  64                 else:
  65                         return unicode(SafeException.__str__(self))
  66
  67 def _split_arch(arch):
  68         """Split an arch into an (os, machine) tuple. Either or both parts may be None."""
  69         if not arch:
  70                 return None, None
  71         elif '-' not in arch:
  72                 raise SafeException(_("Malformed arch '%s'") % arch)
  73         else:
  74                 osys, machine = arch.split('-', 1)
  75                 if osys == '*': osys = None
  76                 if machine == '*': machine = None
  77                 return osys, machine
  78
  79 def _join_arch(osys, machine):
  80         if osys == machine == None: return None
  81         return "%s-%s" % (osys or '*', machine or '*')
  82
  83 def _best_language_match(options):
  84         (language, encoding) = locale.getlocale()
  85
  86         if language:
  87                 # xml:lang uses '-', while LANG uses '_'
  88                 language = language.replace('_', '-')
  89         else:
  90                 language = 'en-US'
  91
  92         return (options.get(language, None) or                  # Exact match (language+region)
  93                 options.get(language.split('-', 1)[0], None) or # Matching language
  94                 options.get('en', None))                        # English
  95
  96 class Stability(object):
  97         """A stability rating. Each implementation has an upstream stability rating and,
  98         optionally, a user-set rating."""
  99         __slots__ = ['level', 'name', 'description']
 100         def __init__(self, level, name, description):
 101                 self.level = level
 102                 self.name = name
 103                 self.description = description
 104                 assert name not in stability_levels
 105                 stability_levels[name] = self
 106
 107         def __cmp__(self, other):
 108                 return cmp(self.level, other.level)
 109
 110         def __str__(self):
 111                 return self.name
 112
 113         def __repr__(self):
 114                 return _("<Stability: %s>") % self.description
 115
 116 def process_binding(e):
 117         """Internal"""
 118         if e.name == 'environment':
 119                 mode = {
 120                         None: EnvironmentBinding.PREPEND,
 121                         'prepend': EnvironmentBinding.PREPEND,
 122                         'append': EnvironmentBinding.APPEND,
 123                         'replace': EnvironmentBinding.REPLACE,
 124                 }[e.getAttribute('mode')]
 125
 126                 binding = EnvironmentBinding(e.getAttribute('name'),
 127                                              insert = e.getAttribute('insert'),
 128                                              default = e.getAttribute('default'),
 129                                              value = e.getAttribute('value'),
 130                                              mode = mode,
 131                                              separator = e.getAttribute('separator'))
 132                 if not binding.name: raise InvalidInterface(_("Missing 'name' in binding"))
 133                 if binding.insert is None and binding.value is None:
 134                         raise InvalidInterface(_("Missing 'insert' or 'value' in binding"))
 135                 if binding.insert is not None and binding.value is not None:
 136                         raise InvalidInterface(_("Binding contains both 'insert' and 'value'"))
 137                 return binding
 138         elif e.name == 'executable-in-path':
 139                 return ExecutableBinding(e, in_path = True)
 140         elif e.name == 'executable-in-var':
 141                 return ExecutableBinding(e, in_path = False)
 142         elif e.name == 'overlay':
 143                 return OverlayBinding(e.getAttribute('src'), e.getAttribute('mount-point'))
 144         else:
 145                 raise Exception(_("Unknown binding type '%s'") % e.name)
 146
 147 def process_depends(item, local_feed_dir):
 148         """Internal"""
 149         # Note: also called from selections
 150         attrs = item.attrs
 151         dep_iface = item.getAttribute('interface')
 152         if not dep_iface:
 153                 raise InvalidInterface(_("Missing 'interface' on <%s>") % item.name)
 154         if dep_iface.startswith('./'):
 155                 if local_feed_dir:
 156                         dep_iface = os.path.abspath(os.path.join(local_feed_dir, dep_iface))
 157                         # (updates the element too, in case we write it out again)
 158                         attrs['interface'] = dep_iface
 159                 else:
 160                         raise InvalidInterface(_('Relative interface URI "%s" in non-local feed') % dep_iface)
 161         dependency = InterfaceDependency(dep_iface, element = item)
 162
 163         for e in item.childNodes:
 164                 if e.uri != XMLNS_IFACE: continue
 165                 if e.name in binding_names:
 166                         dependency.bindings.append(process_binding(e))
 167                 elif e.name == 'version':
 168                         dependency.restrictions.append(
 169                                 VersionRangeRestriction(not_before = parse_version(e.getAttribute('not-before')),
 170                                                         before = parse_version(e.getAttribute('before'))))
 171         return dependency
 172
 173 def N_(message): return message
 174
 175 insecure = Stability(0, N_('insecure'), _('This is a security risk'))
 176 buggy = Stability(5, N_('buggy'), _('Known to have serious bugs'))
 177 developer = Stability(10, N_('developer'), _('Work-in-progress - bugs likely'))
 178 testing = Stability(20, N_('testing'), _('Stability unknown - please test!'))
 179 stable = Stability(30, N_('stable'), _('Tested - no serious problems found'))
 180 packaged = Stability(35, N_('packaged'), _('Supplied by the local package manager'))
 181 preferred = Stability(40, N_('preferred'), _('Best of all - must be set manually'))
 182
 183 del N_
 184
 185 class Restriction(object):
 186         """A Restriction limits the allowed implementations of an Interface."""
 187         __slots__ = []
 188
 189         def meets_restriction(self, impl):
 190                 """Called by the L{solver.Solver} to check whether a particular implementation is acceptable.
 191                 @return: False if this implementation is not a possibility
 192                 @rtype: bool
 193                 """
 194                 raise NotImplementedError(_("Abstract"))
 195
 196 class VersionRestriction(Restriction):
 197         """Only select implementations with a particular version number.
 198         @since: 0.40"""
 199
 200         def __init__(self, version):
 201                 """@param version: the required version number
 202                 @see: L{parse_version}; use this to pre-process the version number
 203                 """
 204                 self.version = version
 205
 206         def meets_restriction(self, impl):
 207                 return impl.version == self.version
 208
 209         def __str__(self):
 210                 return _("(restriction: version = %s)") % format_version(self.version)
 211
 212 class VersionRangeRestriction(Restriction):
 213         """Only versions within the given range are acceptable"""
 214         __slots__ = ['before', 'not_before']
 215
 216         def __init__(self, before, not_before):
 217                 """@param before: chosen versions must be earlier than this
 218                 @param not_before: versions must be at least this high
 219                 @see: L{parse_version}; use this to pre-process the versions
 220                 """
 221                 self.before = before
 222                 self.not_before = not_before
 223
 224         def meets_restriction(self, impl):
 225                 if self.not_before and impl.version < self.not_before:
 226                         return False
 227                 if self.before and impl.version >= self.before:
 228                         return False
 229                 return True
 230
 231         def __str__(self):
 232                 if self.not_before is not None or self.before is not None:
 233                         range = ''
 234                         if self.not_before is not None:
 235                                 range += format_version(self.not_before) + ' <= '
 236                         range += 'version'
 237                         if self.before is not None:
 238                                 range += ' < ' + format_version(self.before)
 239                 else:
 240                         range = 'none'
 241                 return _("(restriction: %s)") % range
 242
 243 class Binding(object):
 244         """Information about how the choice of a Dependency is made known
 245         to the application being run."""
 246
 247         @property
 248         def command(self):
 249                 """"Returns the name of the specific command needed by this binding, if any.
 250                 @since: 1.2"""
 251                 return None
 252
 253 class EnvironmentBinding(Binding):
 254         """Indicate the chosen implementation using an environment variable."""
 255         __slots__ = ['name', 'insert', 'default', 'mode', 'value']
 256
 257         PREPEND = 'prepend'
 258         APPEND = 'append'
 259         REPLACE = 'replace'
 260
 261         def __init__(self, name, insert, default = None, mode = PREPEND, value=None, separator=None):
 262                 """
 263                 mode argument added in version 0.28
 264                 value argument added in version 0.52
 265                 """
 266                 self.name = name
 267                 self.insert = insert
 268                 self.default = default
 269                 self.mode = mode
 270                 self.value = value
 271                 if separator is None:
 272                         self.separator = os.pathsep
 273                 else:
 274                         self.separator = separator
 275
 276
 277         def __str__(self):
 278                 return _("<environ %(name)s %(mode)s %(insert)s %(value)s>") % {'name': self.name,'mode': self.mode, 'insert': self.insert, 'value': self.value}
 279
 280         __repr__ = __str__
 281
 282         def get_value(self, path, old_value):
 283                 """Calculate the new value of the environment variable after applying this binding.
 284                 @param path: the path to the selected implementation
 285                 @param old_value: the current value of the environment variable
 286                 @return: the new value for the environment variable"""
 287
 288                 if self.insert is not None:
 289                         extra = os.path.join(path, self.insert)
 290                 else:
 291                         assert self.value is not None
 292                         extra = self.value
 293
 294                 if self.mode == EnvironmentBinding.REPLACE:
 295                         return extra
 296
 297                 if old_value is None:
 298                         old_value = self.default or defaults.get(self.name, None)
 299                 if old_value is None:
 300                         return extra
 301                 if self.mode == EnvironmentBinding.PREPEND:
 302                         return extra + self.separator + old_value
 303                 else:
 304                         return old_value + self.separator + extra
 305
 306         def _toxml(self, doc, prefixes):
 307                 """Create a DOM element for this binding.
 308                 @param doc: document to use to create the element
 309                 @return: the new element
 310                 """
 311                 env_elem = doc.createElementNS(XMLNS_IFACE, 'environment')
 312                 env_elem.setAttributeNS(None, 'name', self.name)
 313                 if self.mode is not None:
 314                         env_elem.setAttributeNS(None, 'mode', self.mode)
 315                 if self.insert is not None:
 316                         env_elem.setAttributeNS(None, 'insert', self.insert)
 317                 else:
 318                         env_elem.setAttributeNS(None, 'value', self.value)
 319                 if self.default:
 320                         env_elem.setAttributeNS(None, 'default', self.default)
 321                 if self.separator:
 322                         env_elem.setAttributeNS(None, 'separator', self.separator)
 323                 return env_elem
 324
 325 class ExecutableBinding(Binding):
 326         """Make the chosen command available in $PATH.
 327         @ivar in_path: True to add the named command to $PATH, False to store in named variable
 328         @type in_path: bool
 329         """
 330         __slots__ = ['qdom']
 331
 332         def __init__(self, qdom, in_path):
 333                 self.qdom = qdom
 334                 self.in_path = in_path
 335
 336         def __str__(self):
 337                 return str(self.qdom)
 338
 339         __repr__ = __str__
 340
 341         def _toxml(self, doc, prefixes):
 342                 return self.qdom.toDOM(doc, prefixes)
 343
 344         @property
 345         def name(self):
 346                 return self.qdom.getAttribute('name')
 347
 348         @property
 349         def command(self):
 350                 return self.qdom.getAttribute("command") or 'run'
 351
 352 class OverlayBinding(Binding):
 353         """Make the chosen implementation available by overlaying it onto another part of the file-system.
 354         This is to support legacy programs which use hard-coded paths."""
 355         __slots__ = ['src', 'mount_point']
 356
 357         def __init__(self, src, mount_point):
 358                 self.src = src
 359                 self.mount_point = mount_point
 360
 361         def __str__(self):
 362                 return _("<overlay %(src)s on %(mount_point)s>") % {'src': self.src or '.', 'mount_point': self.mount_point or '/'}
 363
 364         __repr__ = __str__
 365
 366         def _toxml(self, doc):
 367                 """Create a DOM element for this binding.
 368                 @param doc: document to use to create the element
 369                 @return: the new element
 370                 """
 371                 env_elem = doc.createElementNS(XMLNS_IFACE, 'overlay')
 372                 if self.src is not None:
 373                         env_elem.setAttributeNS(None, 'src', self.src)
 374                 if self.mount_point is not None:
 375                         env_elem.setAttributeNS(None, 'mount-point', self.mount_point)
 376                 return env_elem
 377
 378 class Feed(object):
 379         """An interface's feeds are other interfaces whose implementations can also be
 380         used as implementations of this interface."""
 381         __slots__ = ['uri', 'os', 'machine', 'user_override', 'langs']
 382         def __init__(self, uri, arch, user_override, langs = None):
 383                 self.uri = uri
 384                 # This indicates whether the feed comes from the user's overrides
 385                 # file. If true, writer.py will write it when saving.
 386                 self.user_override = user_override
 387                 self.os, self.machine = _split_arch(arch)
 388                 self.langs = langs
 389
 390         def __str__(self):
 391                 return "<Feed from %s>" % self.uri
 392         __repr__ = __str__
 393
 394         arch = property(lambda self: _join_arch(self.os, self.machine))
 395
 396 class Dependency(object):
 397         """A Dependency indicates that an Implementation requires some additional
 398         code to function. This is an abstract base class.
 399         @ivar qdom: the XML element for this Dependency (since 0launch 0.51)
 400         @type qdom: L{qdom.Element}
 401         @ivar metadata: any extra attributes from the XML element
 402         @type metadata: {str: str}
 403         """
 404         __slots__ = ['qdom']
 405
 406         Essential = "essential"
 407         Recommended = "recommended"
 408
 409         def __init__(self, element):
 410                 assert isinstance(element, qdom.Element), type(element) # Use InterfaceDependency instead!
 411                 self.qdom = element
 412
 413         @property
 414         def metadata(self):
 415                 return self.qdom.attrs
 416
 417         @property
 418         def importance(self):
 419                 return self.qdom.getAttribute("importance") or Dependency.Essential
 420
 421         def get_required_commands(self):
 422                 """Return a list of command names needed by this dependency"""
 423                 return []
 424
 425 class InterfaceDependency(Dependency):
 426         """A Dependency on a Zero Install interface.
 427         @ivar interface: the interface required by this dependency
 428         @type interface: str
 429         @ivar restrictions: a list of constraints on acceptable implementations
 430         @type restrictions: [L{Restriction}]
 431         @ivar bindings: how to make the choice of implementation known
 432         @type bindings: [L{Binding}]
 433         @since: 0.28
 434         """
 435         __slots__ = ['interface', 'restrictions', 'bindings']
 436
 437         def __init__(self, interface, restrictions = None, element = None):
 438                 Dependency.__init__(self, element)
 439                 assert isinstance(interface, (str, unicode))
 440                 assert interface
 441                 self.interface = interface
 442                 if restrictions is None:
 443                         self.restrictions = []
 444                 else:
 445                         self.restrictions = restrictions
 446                 self.bindings = []
 447
 448         def __str__(self):
 449                 return _("<Dependency on %(interface)s; bindings: %(bindings)s%(restrictions)s>") % {'interface': self.interface, 'bindings': self.bindings, 'restrictions': self.restrictions}
 450
 451         def get_required_commands(self):
 452                 """Return a list of command names needed by this dependency"""
 453                 if self.qdom.name == 'runner':
 454                         commands = [self.qdom.getAttribute('command') or 'run']
 455                 else:
 456                         commands = []
 457                 for b in self.bindings:
 458                         c = b.command
 459                         if c is not None:
 460                                 commands.append(c)
 461                 return commands
 462
 463         @property
 464         def command(self):
 465                 if self.qdom.name == 'runner':
 466                         return self.qdom.getAttribute('command') or 'run'
 467                 return None
 468
 469 class RetrievalMethod(object):
 470         """A RetrievalMethod provides a way to fetch an implementation."""
 471         __slots__ = []
 472
 473 class DownloadSource(RetrievalMethod):
 474         """A DownloadSource provides a way to fetch an implementation."""
 475         __slots__ = ['implementation', 'url', 'size', 'extract', 'start_offset', 'type']
 476
 477         def __init__(self, implementation, url, size, extract, start_offset = 0, type = None):
 478                 self.implementation = implementation
 479                 self.url = url
 480                 self.size = size
 481                 self.extract = extract
 482                 self.start_offset = start_offset
 483                 self.type = type                # MIME type - see unpack.py
 484
 485 class Recipe(RetrievalMethod):
 486         """Get an implementation by following a series of steps.
 487         @ivar size: the combined download sizes from all the steps
 488         @type size: int
 489         @ivar steps: the sequence of steps which must be performed
 490         @type steps: [L{RetrievalMethod}]"""
 491         __slots__ = ['steps']
 492
 493         def __init__(self):
 494                 self.steps = []
 495
 496         size = property(lambda self: sum([x.size for x in self.steps]))
 497
 498 class DistributionSource(RetrievalMethod):
 499         """A package that is installed using the distribution's tools (including PackageKit).
 500         @ivar install: a function to call to install this package
 501         @type install: (L{handler.Handler}) -> L{tasks.Blocker}
 502         @ivar package_id: the package name, in a form recognised by the distribution's tools
 503         @type package_id: str
 504         @ivar size: the download size in bytes
 505         @type size: int
 506         @ivar needs_confirmation: whether the user should be asked to confirm before calling install()
 507         @type needs_confirmation: bool"""
 508
 509         __slots__ = ['package_id', 'size', 'install', 'needs_confirmation']
 510
 511         def __init__(self, package_id, size, install, needs_confirmation = True):
 512                 RetrievalMethod.__init__(self)
 513                 self.package_id = package_id
 514                 self.size = size
 515                 self.install = install
 516                 self.needs_confirmation = needs_confirmation
 517
 518 class Command(object):
 519         """A Command is a way of running an Implementation as a program."""
 520
 521         __slots__ = ['qdom', '_depends', '_local_dir', '_runner', '_bindings']
 522
 523         def __init__(self, qdom, local_dir):
 524                 """@param qdom: the <command> element
 525                 @param local_dir: the directory containing the feed (for relative dependencies), or None if not local
 526                 """
 527                 assert qdom.name == 'command', 'not <command>: %s' % qdom
 528                 self.qdom = qdom
 529                 self._local_dir = local_dir
 530                 self._depends = None
 531                 self._bindings = None
 532
 533         path = property(lambda self: self.qdom.attrs.get("path", None))
 534
 535         def _toxml(self, doc, prefixes):
 536                 return self.qdom.toDOM(doc, prefixes)
 537
 538         @property
 539         def requires(self):
 540                 if self._depends is None:
 541                         self._runner = None
 542                         depends = []
 543                         for child in self.qdom.childNodes:
 544                                 if child.name == 'requires':
 545                                         dep = process_depends(child, self._local_dir)
 546                                         depends.append(dep)
 547                                 elif child.name == 'runner':
 548                                         if self._runner:
 549                                                 raise InvalidInterface(_("Multiple <runner>s in <command>!"))
 550                                         dep = process_depends(child, self._local_dir)
 551                                         depends.append(dep)
 552                                         self._runner = dep
 553                         self._depends = depends
 554                 return self._depends
 555
 556         def get_runner(self):
 557                 self.requires           # (sets _runner)
 558                 return self._runner
 559
 560         def __str__(self):
 561                 return str(self.qdom)
 562
 563         @property
 564         def bindings(self):
 565                 """@since: 1.3"""
 566                 if self._bindings is None:
 567                         bindings = []
 568                         for e in self.qdom.childNodes:
 569                                 if e.uri != XMLNS_IFACE: continue
 570                                 if e.name in binding_names:
 571                                         bindings.append(process_binding(e))
 572                         self._bindings = bindings
 573                 return self._bindings
 574
 575 class Implementation(object):
 576         """An Implementation is a package which implements an Interface.
 577         @ivar download_sources: list of methods of getting this implementation
 578         @type download_sources: [L{RetrievalMethod}]
 579         @ivar feed: the feed owning this implementation (since 0.32)
 580         @type feed: [L{ZeroInstallFeed}]
 581         @ivar bindings: how to tell this component where it itself is located (since 0.31)
 582         @type bindings: [Binding]
 583         @ivar upstream_stability: the stability reported by the packager
 584         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged]
 585         @ivar user_stability: the stability as set by the user
 586         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged | preferred]
 587         @ivar langs: natural languages supported by this package
 588         @type langs: str
 589         @ivar requires: interfaces this package depends on
 590         @type requires: [L{Dependency}]
 591         @ivar commands: ways to execute as a program
 592         @type commands: {str: Command}
 593         @ivar metadata: extra metadata from the feed
 594         @type metadata: {"[URI ]localName": str}
 595         @ivar id: a unique identifier for this Implementation
 596         @ivar version: a parsed version number
 597         @ivar released: release date
 598         @ivar local_path: the directory containing this local implementation, or None if it isn't local (id isn't a path)
 599         @type local_path: str | None
 600         @ivar requires_root_install: whether the user will need admin rights to use this
 601         @type requires_root_install: bool
 602         """
 603
 604         # Note: user_stability shouldn't really be here
 605
 606         __slots__ = ['upstream_stability', 'user_stability', 'langs',
 607                      'requires', 'metadata', 'download_sources', 'commands',
 608                      'id', 'feed', 'version', 'released', 'bindings', 'machine']
 609
 610         def __init__(self, feed, id):
 611                 assert id
 612                 self.feed = feed
 613                 self.id = id
 614                 self.user_stability = None
 615                 self.upstream_stability = None
 616                 self.metadata = {}      # [URI + " "] + localName -> value
 617                 self.requires = []
 618                 self.version = None
 619                 self.released = None
 620                 self.download_sources = []
 621                 self.langs = ""
 622                 self.machine = None
 623                 self.bindings = []
 624                 self.commands = {}
 625
 626         def get_stability(self):
 627                 return self.user_stability or self.upstream_stability or testing
 628
 629         def __str__(self):
 630                 return self.id
 631
 632         def __repr__(self):
 633                 return "v%s (%s)" % (self.get_version(), self.id)
 634
 635         def __cmp__(self, other):
 636                 """Newer versions come first"""
 637                 d = cmp(other.version, self.version)
 638                 if d: return d
 639                 # If the version number is the same, just give a stable sort order, and
 640                 # ensure that two different implementations don't compare equal.
 641                 d = cmp(other.feed.url, self.feed.url)
 642                 if d: return d
 643                 return cmp(other.id, self.id)
 644
 645         def get_version(self):
 646                 """Return the version as a string.
 647                 @see: L{format_version}
 648                 """
 649                 return format_version(self.version)
 650
 651         arch = property(lambda self: _join_arch(self.os, self.machine))
 652
 653         os = None
 654         local_path = None
 655         digests = None
 656         requires_root_install = False
 657
 658         def _get_main(self):
 659                 """"@deprecated: use commands["run"] instead"""
 660                 main = self.commands.get("run", None)
 661                 if main is not None:
 662                         return main.path
 663                 return None
 664         def _set_main(self, path):
 665                 """"@deprecated: use commands["run"] instead"""
 666                 if path is None:
 667                         if "run" in self.commands:
 668                                 del self.commands["run"]
 669                 else:
 670                         self.commands["run"] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': path, 'name': 'run'}), None)
 671         main = property(_get_main, _set_main)
 672
 673         def is_available(self, stores):
 674                 """Is this Implementation available locally?
 675                 (a local implementation, an installed distribution package, or a cached ZeroInstallImplementation)
 676                 @rtype: bool
 677                 @since: 0.53
 678                 """
 679                 raise NotImplementedError("abstract")
 680
 681 class DistributionImplementation(Implementation):
 682         """An implementation provided by the distribution. Information such as the version
 683         comes from the package manager.
 684         @since: 0.28"""
 685         __slots__ = ['distro', 'installed']
 686
 687         def __init__(self, feed, id, distro):
 688                 assert id.startswith('package:')
 689                 Implementation.__init__(self, feed, id)
 690                 self.distro = distro
 691                 self.installed = False
 692
 693         @property
 694         def requires_root_install(self):
 695                 return not self.installed
 696
 697         def is_available(self, stores):
 698                 return self.installed
 699
 700 class ZeroInstallImplementation(Implementation):
 701         """An implementation where all the information comes from Zero Install.
 702         @ivar digests: a list of "algorith=value" strings (since 0.45)
 703         @type digests: [str]
 704         @since: 0.28"""
 705         __slots__ = ['os', 'size', 'digests', 'local_path']
 706
 707         def __init__(self, feed, id, local_path):
 708                 """id can be a local path (string starting with /) or a manifest hash (eg "sha1=XXX")"""
 709                 assert not id.startswith('package:'), id
 710                 Implementation.__init__(self, feed, id)
 711                 self.size = None
 712                 self.os = None
 713                 self.digests = []
 714                 self.local_path = local_path
 715
 716         # Deprecated
 717         dependencies = property(lambda self: dict([(x.interface, x) for x in self.requires
 718                                                    if isinstance(x, InterfaceDependency)]))
 719
 720         def add_download_source(self, url, size, extract, start_offset = 0, type = None):
 721                 """Add a download source."""
 722                 self.download_sources.append(DownloadSource(self, url, size, extract, start_offset, type))
 723
 724         def set_arch(self, arch):
 725                 self.os, self.machine = _split_arch(arch)
 726         arch = property(lambda self: _join_arch(self.os, self.machine), set_arch)
 727
 728         def is_available(self, stores):
 729                 if self.local_path is not None:
 730                         return os.path.exists(self.local_path)
 731                 if self.digests:
 732                         path = stores.lookup_maybe(self.digests)
 733                         return path is not None
 734                 return False    # (0compile creates fake entries with no digests)
 735
 736 class Interface(object):
 737         """An Interface represents some contract of behaviour.
 738         @ivar uri: the URI for this interface.
 739         @ivar stability_policy: user's configured policy.
 740         Implementations at this level or higher are preferred.
 741         Lower levels are used only if there is no other choice.
 742         """
 743         __slots__ = ['uri', 'stability_policy', 'extra_feeds']
 744
 745         implementations = property(lambda self: self._main_feed.implementations)
 746         name = property(lambda self: self._main_feed.name)
 747         description = property(lambda self: self._main_feed.description)
 748         summary = property(lambda self: self._main_feed.summary)
 749         last_modified = property(lambda self: self._main_feed.last_modified)
 750         feeds = property(lambda self: self.extra_feeds + self._main_feed.feeds)
 751         metadata = property(lambda self: self._main_feed.metadata)
 752
 753         last_checked = property(lambda self: self._main_feed.last_checked)
 754
 755         def __init__(self, uri):
 756                 assert uri
 757                 if uri.startswith('http:') or uri.startswith('https:') or os.path.isabs(uri):
 758                         self.uri = uri
 759                 else:
 760                         raise SafeException(_("Interface name '%s' doesn't start "
 761                                             "with 'http:' or 'https:'") % uri)
 762                 self.reset()
 763
 764         def _get_feed_for(self):
 765                 retval = {}
 766                 for key in self._main_feed.feed_for:
 767                         retval[key] = True
 768                 return retval
 769         feed_for = property(_get_feed_for)      # Deprecated (used by 0publish)
 770
 771         def reset(self):
 772                 self.extra_feeds = []
 773                 self.stability_policy = None
 774
 775         def get_name(self):
 776                 from zeroinstall.injector.iface_cache import iface_cache
 777                 feed = iface_cache.get_feed(self.uri)
 778                 if feed:
 779                         return feed.get_name()
 780                 return '(' + os.path.basename(self.uri) + ')'
 781
 782         def __repr__(self):
 783                 return _("<Interface %s>") % self.uri
 784
 785         def set_stability_policy(self, new):
 786                 assert new is None or isinstance(new, Stability)
 787                 self.stability_policy = new
 788
 789         def get_feed(self, url):
 790                 #import warnings
 791                 #warnings.warn("use iface_cache.get_feed instead", DeprecationWarning, 2)
 792                 for x in self.extra_feeds:
 793                         if x.uri == url:
 794                                 return x
 795                 #return self._main_feed.get_feed(url)
 796                 return None
 797
 798         def get_metadata(self, uri, name):
 799                 return self._main_feed.get_metadata(uri, name)
 800
 801         @property
 802         def _main_feed(self):
 803                 #import warnings
 804                 #warnings.warn("use the feed instead", DeprecationWarning, 3)
 805                 from zeroinstall.injector import policy
 806                 iface_cache = policy.get_deprecated_singleton_config().iface_cache
 807                 feed = iface_cache.get_feed(self.uri)
 808                 if feed is None:
 809                         return _dummy_feed
 810                 return feed
 811
 812 def _merge_attrs(attrs, item):
 813         """Add each attribute of item to a copy of attrs and return the copy.
 814         @type attrs: {str: str}
 815         @type item: L{qdom.Element}
 816         @rtype: {str: str}
 817         """
 818         new = attrs.copy()
 819         for a in item.attrs:
 820                 new[str(a)] = item.attrs[a]
 821         return new
 822
 823 def _get_long(elem, attr_name):
 824         val = elem.getAttribute(attr_name)
 825         if val is not None:
 826                 try:
 827                         val = int(val)
 828                 except ValueError:
 829                         raise SafeException(_("Invalid value for integer attribute '%(attribute_name)s': %(value)s") % {'attribute_name': attr_name, 'value': val})
 830         return val
 831
 832 class ZeroInstallFeed(object):
 833         """A feed lists available implementations of an interface.
 834         @ivar url: the URL for this feed
 835         @ivar implementations: Implementations in this feed, indexed by ID
 836         @type implementations: {str: L{Implementation}}
 837         @ivar name: human-friendly name
 838         @ivar summaries: short textual description (in various languages, since 0.49)
 839         @type summaries: {str: str}
 840         @ivar descriptions: long textual description (in various languages, since 0.49)
 841         @type descriptions: {str: str}
 842         @ivar last_modified: timestamp on signature
 843         @ivar last_checked: time feed was last successfully downloaded and updated
 844         @ivar feeds: list of <feed> elements in this feed
 845         @type feeds: [L{Feed}]
 846         @ivar feed_for: interfaces for which this could be a feed
 847         @type feed_for: set(str)
 848         @ivar metadata: extra elements we didn't understand
 849         """
 850         # _main is deprecated
 851         __slots__ = ['url', 'implementations', 'name', 'descriptions', 'first_description', 'summaries', 'first_summary', '_package_implementations',
 852                      'last_checked', 'last_modified', 'feeds', 'feed_for', 'metadata']
 853
 854         def __init__(self, feed_element, local_path = None, distro = None):
 855                 """Create a feed object from a DOM.
 856                 @param feed_element: the root element of a feed file
 857                 @type feed_element: L{qdom.Element}
 858                 @param local_path: the pathname of this local feed, or None for remote feeds"""
 859                 self.implementations = {}
 860                 self.name = None
 861                 self.summaries = {}     # { lang: str }
 862                 self.first_summary = None
 863                 self.descriptions = {}  # { lang: str }
 864                 self.first_description = None
 865                 self.last_modified = None
 866                 self.feeds = []
 867                 self.feed_for = set()
 868                 self.metadata = []
 869                 self.last_checked = None
 870                 self._package_implementations = []
 871
 872                 if distro is not None:
 873                         import warnings
 874                         warnings.warn("distro argument is now ignored", DeprecationWarning, 2)
 875
 876                 if feed_element is None:
 877                         return                  # XXX subclass?
 878
 879                 assert feed_element.name in ('interface', 'feed'), "Root element should be <interface>, not %s" % feed_element
 880                 assert feed_element.uri == XMLNS_IFACE, "Wrong namespace on root element: %s" % feed_element.uri
 881
 882                 main = feed_element.getAttribute('main')
 883                 #if main: warn("Setting 'main' on the root element is deprecated. Put it on a <group> instead")
 884
 885                 if local_path:
 886                         self.url = local_path
 887                         local_dir = os.path.dirname(local_path)
 888                 else:
 889                         self.url = feed_element.getAttribute('uri')
 890                         if not self.url:
 891                                 raise InvalidInterface(_("<interface> uri attribute missing"))
 892                         local_dir = None        # Can't have relative paths
 893
 894                 min_injector_version = feed_element.getAttribute('min-injector-version')
 895                 if min_injector_version:
 896                         if parse_version(min_injector_version) > parse_version(version):
 897                                 raise InvalidInterface(_("This feed requires version %(min_version)s or later of "
 898                                                         "Zero Install, but I am only version %(version)s. "
 899                                                         "You can get a newer version from http://0install.net") %
 900                                                         {'min_version': min_injector_version, 'version': version})
 901
 902                 for x in feed_element.childNodes:
 903                         if x.uri != XMLNS_IFACE:
 904                                 self.metadata.append(x)
 905                                 continue
 906                         if x.name == 'name':
 907                                 self.name = x.content
 908                         elif x.name == 'description':
 909                                 if self.first_description == None:
 910                                         self.first_description = x.content
 911                                 self.descriptions[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 912                         elif x.name == 'summary':
 913                                 if self.first_summary == None:
 914                                         self.first_summary = x.content
 915                                 self.summaries[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 916                         elif x.name == 'feed-for':
 917                                 feed_iface = x.getAttribute('interface')
 918                                 if not feed_iface:
 919                                         raise InvalidInterface(_('Missing "interface" attribute in <feed-for>'))
 920                                 self.feed_for.add(feed_iface)
 921                                 # Bug report from a Debian/stable user that --feed gets the wrong value.
 922                                 # Can't reproduce (even in a Debian/stable chroot), but add some logging here
 923                                 # in case it happens again.
 924                                 debug(_("Is feed-for %s"), feed_iface)
 925                         elif x.name == 'feed':
 926                                 feed_src = x.getAttribute('src')
 927                                 if not feed_src:
 928                                         raise InvalidInterface(_('Missing "src" attribute in <feed>'))
 929                                 if feed_src.startswith('http:') or feed_src.startswith('https:') or local_path:
 930                                         langs = x.getAttribute('langs')
 931                                         if langs: langs = langs.replace('_', '-')
 932                                         self.feeds.append(Feed(feed_src, x.getAttribute('arch'), False, langs = langs))
 933                                 else:
 934                                         raise InvalidInterface(_("Invalid feed URL '%s'") % feed_src)
 935                         else:
 936                                 self.metadata.append(x)
 937
 938                 if not self.name:
 939                         raise InvalidInterface(_("Missing <name> in feed"))
 940                 if not self.summary:
 941                         raise InvalidInterface(_("Missing <summary> in feed"))
 942
 943                 def process_group(group, group_attrs, base_depends, base_bindings, base_commands):
 944                         for item in group.childNodes:
 945                                 if item.uri != XMLNS_IFACE: continue
 946
 947                                 if item.name not in ('group', 'implementation', 'package-implementation'):
 948                                         continue
 949
 950                                 # We've found a group or implementation. Scan for dependencies,
 951                                 # bindings and commands. Doing this here means that:
 952                                 # - We can share the code for groups and implementations here.
 953                                 # - The order doesn't matter, because these get processed first.
 954                                 # A side-effect is that the document root cannot contain
 955                                 # these.
 956
 957                                 depends = base_depends[:]
 958                                 bindings = base_bindings[:]
 959                                 commands = base_commands.copy()
 960
 961                                 for attr, command in [('main', 'run'),
 962                                                       ('self-test', 'test')]:
 963                                         value = item.attrs.get(attr, None)
 964                                         if value is not None:
 965                                                 commands[command] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': command, 'path': value}), None)
 966
 967                                 for child in item.childNodes:
 968                                         if child.uri != XMLNS_IFACE: continue
 969                                         if child.name == 'requires':
 970                                                 dep = process_depends(child, local_dir)
 971                                                 depends.append(dep)
 972                                         elif child.name == 'command':
 973                                                 command_name = child.attrs.get('name', None)
 974                                                 if not command_name:
 975                                                         raise InvalidInterface('Missing name for <command>')
 976                                                 commands[command_name] = Command(child, local_dir)
 977                                         elif child.name in binding_names:
 978                                                 bindings.append(process_binding(child))
 979
 980                                 compile_command = item.attrs.get('http://zero-install.sourceforge.net/2006/namespaces/0compile command')
 981                                 if compile_command is not None:
 982                                         commands['compile'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': 'compile', 'shell-command': compile_command}), None)
 983
 984                                 item_attrs = _merge_attrs(group_attrs, item)
 985
 986                                 if item.name == 'group':
 987                                         process_group(item, item_attrs, depends, bindings, commands)
 988                                 elif item.name == 'implementation':
 989                                         process_impl(item, item_attrs, depends, bindings, commands)
 990                                 elif item.name == 'package-implementation':
 991                                         if depends:
 992                                                 warn("A <package-implementation> with dependencies in %s!", self.url)
 993                                         self._package_implementations.append((item, item_attrs))
 994                                 else:
 995                                         assert 0
 996
 997                 def process_impl(item, item_attrs, depends, bindings, commands):
 998                         id = item.getAttribute('id')
 999                         if id is None:
1000                                 raise InvalidInterface(_("Missing 'id' attribute on %s") % item)
1001                         local_path = item_attrs.get('local-path')
1002                         if local_dir and local_path:
1003                                 abs_local_path = os.path.abspath(os.path.join(local_dir, local_path))
1004                                 impl = ZeroInstallImplementation(self, id, abs_local_path)
1005                         elif local_dir and (id.startswith('/') or id.startswith('.')):
1006                                 # For old feeds
1007                                 id = os.path.abspath(os.path.join(local_dir, id))
1008                                 impl = ZeroInstallImplementation(self, id, id)
1009                         else:
1010                                 impl = ZeroInstallImplementation(self, id, None)
1011                                 if '=' in id:
1012                                         # In older feeds, the ID was the (single) digest
1013                                         impl.digests.append(id)
1014                         if id in self.implementations:
1015                                 warn(_("Duplicate ID '%(id)s' in feed '%(feed)s'"), {'id': id, 'feed': self})
1016                         self.implementations[id] = impl
1017
1018                         impl.metadata = item_attrs
1019                         try:
1020                                 version_mod = item_attrs.get('version-modifier', None)
1021                                 if version_mod:
1022                                         item_attrs['version'] += version_mod
1023                                         del item_attrs['version-modifier']
1024                                 version = item_attrs['version']
1025                         except KeyError:
1026                                 raise InvalidInterface(_("Missing version attribute"))
1027                         impl.version = parse_version(version)
1028
1029                         impl.commands = commands
1030
1031                         impl.released = item_attrs.get('released', None)
1032                         impl.langs = item_attrs.get('langs', '').replace('_', '-')
1033
1034                         size = item.getAttribute('size')
1035                         if size:
1036                                 impl.size = int(size)
1037                         impl.arch = item_attrs.get('arch', None)
1038                         try:
1039                                 stability = stability_levels[str(item_attrs['stability'])]
1040                         except KeyError:
1041                                 stab = str(item_attrs['stability'])
1042                                 if stab != stab.lower():
1043                                         raise InvalidInterface(_('Stability "%s" invalid - use lower case!') % item_attrs.stability)
1044                                 raise InvalidInterface(_('Stability "%s" invalid') % item_attrs['stability'])
1045                         if stability >= preferred:
1046                                 raise InvalidInterface(_("Upstream can't set stability to preferred!"))
1047                         impl.upstream_stability = stability
1048
1049                         impl.bindings = bindings
1050                         impl.requires = depends
1051
1052                         for elem in item.childNodes:
1053                                 if elem.uri != XMLNS_IFACE: continue
1054                                 if elem.name == 'archive':
1055                                         url = elem.getAttribute('href')
1056                                         if not url:
1057                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1058                                         size = elem.getAttribute('size')
1059                                         if not size:
1060                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1061                                         impl.add_download_source(url = url, size = int(size),
1062                                                         extract = elem.getAttribute('extract'),
1063                                                         start_offset = _get_long(elem, 'start-offset'),
1064                                                         type = elem.getAttribute('type'))
1065                                 elif elem.name == 'manifest-digest':
1066                                         for aname, avalue in elem.attrs.iteritems():
1067                                                 if ' ' not in aname:
1068                                                         impl.digests.append('%s=%s' % (aname, avalue))
1069                                 elif elem.name == 'recipe':
1070                                         recipe = Recipe()
1071                                         for recipe_step in elem.childNodes:
1072                                                 if recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'archive':
1073                                                         url = recipe_step.getAttribute('href')
1074                                                         if not url:
1075                                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1076                                                         size = recipe_step.getAttribute('size')
1077                                                         if not size:
1078                                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1079                                                         recipe.steps.append(DownloadSource(None, url = url, size = int(size),
1080                                                                         extract = recipe_step.getAttribute('extract'),
1081                                                                         start_offset = _get_long(recipe_step, 'start-offset'),
1082                                                                         type = recipe_step.getAttribute('type')))
1083                                                 else:
1084                                                         info(_("Unknown step '%s' in recipe; skipping recipe"), recipe_step.name)
1085                                                         break
1086                                         else:
1087                                                 impl.download_sources.append(recipe)
1088
1089                 root_attrs = {'stability': 'testing'}
1090                 root_commands = {}
1091                 if main:
1092                         info("Note: @main on document element is deprecated in %s", self)
1093                         root_commands['run'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': main, 'name': 'run'}), None)
1094                 process_group(feed_element, root_attrs, [], [], root_commands)
1095
1096         def get_distro_feed(self):
1097                 """Does this feed contain any <pacakge-implementation> elements?
1098                 i.e. is it worth asking the package manager for more information?
1099                 @return: the URL of the virtual feed, or None
1100                 @since: 0.49"""
1101                 if self._package_implementations:
1102                         return "distribution:" + self.url
1103                 return None
1104
1105         def get_package_impls(self, distro):
1106                 """Find the best <pacakge-implementation> element(s) for the given distribution.
1107                 @param distro: the distribution to use to rate them
1108                 @type distro: L{distro.Distribution}
1109                 @return: a list of tuples for the best ranked elements
1110                 @rtype: [str]
1111                 @since: 0.49"""
1112                 best_score = 0
1113                 best_impls = []
1114
1115                 for item, item_attrs in self._package_implementations:
1116                         distro_names = item_attrs.get('distributions', '')
1117                         for distro_name in distro_names.split(' '):
1118                                 score = distro.get_score(distro_name)
1119                                 if score > best_score:
1120                                         best_score = score
1121                                         best_impls = []
1122                                 if score == best_score:
1123                                         best_impls.append((item, item_attrs))
1124                 return best_impls
1125
1126         def get_name(self):
1127                 return self.name or '(' + os.path.basename(self.url) + ')'
1128
1129         def __repr__(self):
1130                 return _("<Feed %s>") % self.url
1131
1132         def set_stability_policy(self, new):
1133                 assert new is None or isinstance(new, Stability)
1134                 self.stability_policy = new
1135
1136         def get_feed(self, url):
1137                 for x in self.feeds:
1138                         if x.uri == url:
1139                                 return x
1140                 return None
1141
1142         def add_metadata(self, elem):
1143                 self.metadata.append(elem)
1144
1145         def get_metadata(self, uri, name):
1146                 """Return a list of interface metadata elements with this name and namespace URI."""
1147                 return [m for m in self.metadata if m.name == name and m.uri == uri]
1148
1149         @property
1150         def summary(self):
1151                 return _best_language_match(self.summaries) or self.first_summary
1152
1153         @property
1154         def description(self):
1155                 return _best_language_match(self.descriptions) or self.first_description
1156
1157 class DummyFeed(object):
1158         """Temporary class used during API transition."""
1159         last_modified = None
1160         name = '-'
1161         last_checked = property(lambda self: None)
1162         implementations = property(lambda self: {})
1163         feeds = property(lambda self: [])
1164         summary = property(lambda self: '-')
1165         description = property(lambda self: '')
1166         def get_name(self): return self.name
1167         def get_feed(self, url): return None
1168         def get_metadata(self, uri, name): return []
1169 _dummy_feed = DummyFeed()
1170
1171 def unescape(uri):
1172         """Convert each %20 to a space, etc.
1173         @rtype: str"""
1174         uri = uri.replace('#', '/')
1175         if '%' not in uri: return uri
1176         return re.sub('%[0-9a-fA-F][0-9a-fA-F]',
1177                 lambda match: chr(int(match.group(0)[1:], 16)),
1178                 uri).decode('utf-8')
1179
1180 def escape(uri):
1181         """Convert each space to %20, etc
1182         @rtype: str"""
1183         return re.sub('[^-_.a-zA-Z0-9]',
1184                 lambda match: '%%%02x' % ord(match.group(0)),
1185                 uri.encode('utf-8'))
1186
1187 def _pretty_escape(uri):
1188         """Convert each space to %20, etc
1189         : is preserved and / becomes #. This makes for nicer strings,
1190         and may replace L{escape} everywhere in future.
1191         @rtype: str"""
1192         if os.name == "posix":
1193                 # Only preserve : on Posix systems
1194                 preserveRegex = '[^-_.a-zA-Z0-9:/]'
1195         else:
1196                 # Other OSes may not allow the : character in file names
1197                 preserveRegex = '[^-_.a-zA-Z0-9/]'
1198         return re.sub(preserveRegex,
1199                 lambda match: '%%%02x' % ord(match.group(0)),
1200                 uri.encode('utf-8')).replace('/', '#')
1201
1202 def canonical_iface_uri(uri):
1203         """If uri is a relative path, convert to an absolute one.
1204         A "file:///foo" URI is converted to "/foo".
1205         An "alias:prog" URI expands to the URI in the 0alias script
1206         Otherwise, return it unmodified.
1207         @rtype: str
1208         @raise SafeException: if uri isn't valid
1209         """
1210         if uri.startswith('http://') or uri.startswith('https://'):
1211                 if uri.count("/") < 3:
1212                         raise SafeException(_("Missing / after hostname in URI '%s'") % uri)
1213                 return uri
1214         elif uri.startswith('file:///'):
1215                 return uri[7:]
1216         elif uri.startswith('alias:'):
1217                 from zeroinstall import alias, support
1218                 alias_prog = uri[6:]
1219                 if not os.path.isabs(alias_prog):
1220                         full_path = support.find_in_path(alias_prog)
1221                         if not full_path:
1222                                 raise alias.NotAnAliasScript("Not found in $PATH: " + alias_prog)
1223                 else:
1224                         full_path = alias_prog
1225                 return alias.parse_script(full_path).uri
1226         else:
1227                 iface_uri = os.path.realpath(uri)
1228                 if os.path.isfile(iface_uri):
1229                         return iface_uri
1230         raise SafeException(_("Bad interface name '%(uri)s'.\n"
1231                         "(doesn't start with 'http:', and "
1232                         "doesn't exist as a local file '%(interface_uri)s' either)") %
1233                         {'uri': uri, 'interface_uri': iface_uri})
1234
1235 _version_mod_to_value = {
1236         'pre': -2,
1237         'rc': -1,
1238         '': 0,
1239         'post': 1,
1240 }
1241
1242 # Reverse mapping
1243 _version_value_to_mod = {}
1244 for x in _version_mod_to_value: _version_value_to_mod[_version_mod_to_value[x]] = x
1245 del x
1246
1247 _version_re = re.compile('-([a-z]*)')
1248
1249 def parse_version(version_string):
1250         """Convert a version string to an internal representation.
1251         The parsed format can be compared quickly using the standard Python functions.
1252          - Version := DottedList ("-" Mod DottedList?)*
1253          - DottedList := (Integer ("." Integer)*)
1254         @rtype: tuple (opaque)
1255         @raise SafeException: if the string isn't a valid version
1256         @since: 0.24 (moved from L{reader}, from where it is still available):"""
1257         if version_string is None: return None
1258         parts = _version_re.split(version_string)
1259         if parts[-1] == '':
1260                 del parts[-1]   # Ends with a modifier
1261         else:
1262                 parts.append('')
1263         if not parts:
1264                 raise SafeException(_("Empty version string!"))
1265         l = len(parts)
1266         try:
1267                 for x in range(0, l, 2):
1268                         part = parts[x]
1269                         if part:
1270                                 parts[x] = map(int, parts[x].split('.'))
1271                         else:
1272                                 parts[x] = []   # (because ''.split('.') == [''], not [])
1273                 for x in range(1, l, 2):
1274                         parts[x] = _version_mod_to_value[parts[x]]
1275                 return parts
1276         except ValueError as ex:
1277                 raise SafeException(_("Invalid version format in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1278         except KeyError as ex:
1279                 raise SafeException(_("Invalid version modifier in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1280
1281 def format_version(version):
1282         """Format a parsed version for display. Undoes the effect of L{parse_version}.
1283         @see: L{Implementation.get_version}
1284         @rtype: str
1285         @since: 0.24"""
1286         version = version[:]
1287         l = len(version)
1288         for x in range(0, l, 2):
1289                 version[x] = '.'.join(map(str, version[x]))
1290         for x in range(1, l, 2):
1291                 version[x] = '-' + _version_value_to_mod[version[x]]
1292         if version[-1] == '-': del version[-1]
1293         return ''.join(version)
1294