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, sys
  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 __lt__(self, other):
 111                 if isinstance(other, Stability):
 112                         return self.level < other.level
 113                 else:
 114                         return NotImplemented
 115
 116         def __eq__(self, other):
 117                 if isinstance(other, Stability):
 118                         return self.level == other.level
 119                 else:
 120                         return NotImplemented
 121
 122         def __str__(self):
 123                 return self.name
 124
 125         def __repr__(self):
 126                 return _("<Stability: %s>") % self.description
 127
 128 def process_binding(e):
 129         """Internal"""
 130         if e.name == 'environment':
 131                 mode = {
 132                         None: EnvironmentBinding.PREPEND,
 133                         'prepend': EnvironmentBinding.PREPEND,
 134                         'append': EnvironmentBinding.APPEND,
 135                         'replace': EnvironmentBinding.REPLACE,
 136                 }[e.getAttribute('mode')]
 137
 138                 binding = EnvironmentBinding(e.getAttribute('name'),
 139                                              insert = e.getAttribute('insert'),
 140                                              default = e.getAttribute('default'),
 141                                              value = e.getAttribute('value'),
 142                                              mode = mode,
 143                                              separator = e.getAttribute('separator'))
 144                 if not binding.name: raise InvalidInterface(_("Missing 'name' in binding"))
 145                 if binding.insert is None and binding.value is None:
 146                         raise InvalidInterface(_("Missing 'insert' or 'value' in binding"))
 147                 if binding.insert is not None and binding.value is not None:
 148                         raise InvalidInterface(_("Binding contains both 'insert' and 'value'"))
 149                 return binding
 150         elif e.name == 'executable-in-path':
 151                 return ExecutableBinding(e, in_path = True)
 152         elif e.name == 'executable-in-var':
 153                 return ExecutableBinding(e, in_path = False)
 154         elif e.name == 'overlay':
 155                 return OverlayBinding(e.getAttribute('src'), e.getAttribute('mount-point'))
 156         else:
 157                 raise Exception(_("Unknown binding type '%s'") % e.name)
 158
 159 def process_depends(item, local_feed_dir):
 160         """Internal"""
 161         # Note: also called from selections
 162         attrs = item.attrs
 163         dep_iface = item.getAttribute('interface')
 164         if not dep_iface:
 165                 raise InvalidInterface(_("Missing 'interface' on <%s>") % item.name)
 166         if dep_iface.startswith('.'):
 167                 if local_feed_dir:
 168                         dep_iface = os.path.abspath(os.path.join(local_feed_dir, dep_iface))
 169                         # (updates the element too, in case we write it out again)
 170                         attrs['interface'] = dep_iface
 171                 else:
 172                         raise InvalidInterface(_('Relative interface URI "%s" in non-local feed') % dep_iface)
 173         dependency = InterfaceDependency(dep_iface, element = item)
 174
 175         for e in item.childNodes:
 176                 if e.uri != XMLNS_IFACE: continue
 177                 if e.name in binding_names:
 178                         dependency.bindings.append(process_binding(e))
 179                 elif e.name == 'version':
 180                         dependency.restrictions.append(
 181                                 VersionRangeRestriction(not_before = parse_version(e.getAttribute('not-before')),
 182                                                         before = parse_version(e.getAttribute('before'))))
 183         return dependency
 184
 185 def N_(message): return message
 186
 187 insecure = Stability(0, N_('insecure'), _('This is a security risk'))
 188 buggy = Stability(5, N_('buggy'), _('Known to have serious bugs'))
 189 developer = Stability(10, N_('developer'), _('Work-in-progress - bugs likely'))
 190 testing = Stability(20, N_('testing'), _('Stability unknown - please test!'))
 191 stable = Stability(30, N_('stable'), _('Tested - no serious problems found'))
 192 packaged = Stability(35, N_('packaged'), _('Supplied by the local package manager'))
 193 preferred = Stability(40, N_('preferred'), _('Best of all - must be set manually'))
 194
 195 del N_
 196
 197 class Restriction(object):
 198         """A Restriction limits the allowed implementations of an Interface."""
 199         __slots__ = []
 200
 201         def meets_restriction(self, impl):
 202                 """Called by the L{solver.Solver} to check whether a particular implementation is acceptable.
 203                 @return: False if this implementation is not a possibility
 204                 @rtype: bool
 205                 """
 206                 raise NotImplementedError(_("Abstract"))
 207
 208 class VersionRestriction(Restriction):
 209         """Only select implementations with a particular version number.
 210         @since: 0.40"""
 211
 212         def __init__(self, version):
 213                 """@param version: the required version number
 214                 @see: L{parse_version}; use this to pre-process the version number
 215                 """
 216                 self.version = version
 217
 218         def meets_restriction(self, impl):
 219                 return impl.version == self.version
 220
 221         def __str__(self):
 222                 return _("(restriction: version = %s)") % format_version(self.version)
 223
 224 class VersionRangeRestriction(Restriction):
 225         """Only versions within the given range are acceptable"""
 226         __slots__ = ['before', 'not_before']
 227
 228         def __init__(self, before, not_before):
 229                 """@param before: chosen versions must be earlier than this
 230                 @param not_before: versions must be at least this high
 231                 @see: L{parse_version}; use this to pre-process the versions
 232                 """
 233                 self.before = before
 234                 self.not_before = not_before
 235
 236         def meets_restriction(self, impl):
 237                 if self.not_before and impl.version < self.not_before:
 238                         return False
 239                 if self.before and impl.version >= self.before:
 240                         return False
 241                 return True
 242
 243         def __str__(self):
 244                 if self.not_before is not None or self.before is not None:
 245                         range = ''
 246                         if self.not_before is not None:
 247                                 range += format_version(self.not_before) + ' <= '
 248                         range += 'version'
 249                         if self.before is not None:
 250                                 range += ' < ' + format_version(self.before)
 251                 else:
 252                         range = 'none'
 253                 return _("(restriction: %s)") % range
 254
 255 class Binding(object):
 256         """Information about how the choice of a Dependency is made known
 257         to the application being run."""
 258
 259         @property
 260         def command(self):
 261                 """"Returns the name of the specific command needed by this binding, if any.
 262                 @since: 1.2"""
 263                 return None
 264
 265 class EnvironmentBinding(Binding):
 266         """Indicate the chosen implementation using an environment variable."""
 267         __slots__ = ['name', 'insert', 'default', 'mode', 'value']
 268
 269         PREPEND = 'prepend'
 270         APPEND = 'append'
 271         REPLACE = 'replace'
 272
 273         def __init__(self, name, insert, default = None, mode = PREPEND, value=None, separator=None):
 274                 """
 275                 mode argument added in version 0.28
 276                 value argument added in version 0.52
 277                 """
 278                 self.name = name
 279                 self.insert = insert
 280                 self.default = default
 281                 self.mode = mode
 282                 self.value = value
 283                 if separator is None:
 284                         self.separator = os.pathsep
 285                 else:
 286                         self.separator = separator
 287
 288
 289         def __str__(self):
 290                 return _("<environ %(name)s %(mode)s %(insert)s %(value)s>") % \
 291                         {'name': self.name, 'mode': self.mode, 'insert': self.insert, 'value': self.value}
 292
 293         __repr__ = __str__
 294
 295         def get_value(self, path, old_value):
 296                 """Calculate the new value of the environment variable after applying this binding.
 297                 @param path: the path to the selected implementation
 298                 @param old_value: the current value of the environment variable
 299                 @return: the new value for the environment variable"""
 300
 301                 if self.insert is not None:
 302                         extra = os.path.join(path, self.insert)
 303                 else:
 304                         assert self.value is not None
 305                         extra = self.value
 306
 307                 if self.mode == EnvironmentBinding.REPLACE:
 308                         return extra
 309
 310                 if old_value is None:
 311                         old_value = self.default or defaults.get(self.name, None)
 312                 if old_value is None:
 313                         return extra
 314                 if self.mode == EnvironmentBinding.PREPEND:
 315                         return extra + self.separator + old_value
 316                 else:
 317                         return old_value + self.separator + extra
 318
 319         def _toxml(self, doc, prefixes):
 320                 """Create a DOM element for this binding.
 321                 @param doc: document to use to create the element
 322                 @return: the new element
 323                 """
 324                 env_elem = doc.createElementNS(XMLNS_IFACE, 'environment')
 325                 env_elem.setAttributeNS(None, 'name', self.name)
 326                 if self.mode is not None:
 327                         env_elem.setAttributeNS(None, 'mode', self.mode)
 328                 if self.insert is not None:
 329                         env_elem.setAttributeNS(None, 'insert', self.insert)
 330                 else:
 331                         env_elem.setAttributeNS(None, 'value', self.value)
 332                 if self.default:
 333                         env_elem.setAttributeNS(None, 'default', self.default)
 334                 if self.separator:
 335                         env_elem.setAttributeNS(None, 'separator', self.separator)
 336                 return env_elem
 337
 338 class ExecutableBinding(Binding):
 339         """Make the chosen command available in $PATH.
 340         @ivar in_path: True to add the named command to $PATH, False to store in named variable
 341         @type in_path: bool
 342         """
 343         __slots__ = ['qdom']
 344
 345         def __init__(self, qdom, in_path):
 346                 self.qdom = qdom
 347                 self.in_path = in_path
 348
 349         def __str__(self):
 350                 return str(self.qdom)
 351
 352         __repr__ = __str__
 353
 354         def _toxml(self, doc, prefixes):
 355                 return self.qdom.toDOM(doc, prefixes)
 356
 357         @property
 358         def name(self):
 359                 return self.qdom.getAttribute('name')
 360
 361         @property
 362         def command(self):
 363                 return self.qdom.getAttribute("command") or 'run'
 364
 365 class OverlayBinding(Binding):
 366         """Make the chosen implementation available by overlaying it onto another part of the file-system.
 367         This is to support legacy programs which use hard-coded paths."""
 368         __slots__ = ['src', 'mount_point']
 369
 370         def __init__(self, src, mount_point):
 371                 self.src = src
 372                 self.mount_point = mount_point
 373
 374         def __str__(self):
 375                 return _("<overlay %(src)s on %(mount_point)s>") % {'src': self.src or '.', 'mount_point': self.mount_point or '/'}
 376
 377         __repr__ = __str__
 378
 379         def _toxml(self, doc, prefixes):
 380                 """Create a DOM element for this binding.
 381                 @param doc: document to use to create the element
 382                 @return: the new element
 383                 """
 384                 env_elem = doc.createElementNS(XMLNS_IFACE, 'overlay')
 385                 if self.src is not None:
 386                         env_elem.setAttributeNS(None, 'src', self.src)
 387                 if self.mount_point is not None:
 388                         env_elem.setAttributeNS(None, 'mount-point', self.mount_point)
 389                 return env_elem
 390
 391 class Feed(object):
 392         """An interface's feeds are other interfaces whose implementations can also be
 393         used as implementations of this interface."""
 394         __slots__ = ['uri', 'os', 'machine', 'user_override', 'langs', 'site_package']
 395         def __init__(self, uri, arch, user_override, langs = None, site_package = False):
 396                 self.uri = uri
 397                 # This indicates whether the feed comes from the user's overrides
 398                 # file. If true, writer.py will write it when saving.
 399                 self.user_override = user_override
 400                 self.os, self.machine = _split_arch(arch)
 401                 self.langs = langs
 402                 self.site_package = site_package
 403
 404         def __str__(self):
 405                 return "<Feed from %s>" % self.uri
 406         __repr__ = __str__
 407
 408         arch = property(lambda self: _join_arch(self.os, self.machine))
 409
 410 class Dependency(object):
 411         """A Dependency indicates that an Implementation requires some additional
 412         code to function. This is an abstract base class.
 413         @ivar qdom: the XML element for this Dependency (since 0launch 0.51)
 414         @type qdom: L{qdom.Element}
 415         @ivar metadata: any extra attributes from the XML element
 416         @type metadata: {str: str}
 417         """
 418         __slots__ = ['qdom']
 419
 420         Essential = "essential"
 421         Recommended = "recommended"
 422
 423         def __init__(self, element):
 424                 assert isinstance(element, qdom.Element), type(element) # Use InterfaceDependency instead!
 425                 self.qdom = element
 426
 427         @property
 428         def metadata(self):
 429                 return self.qdom.attrs
 430
 431         @property
 432         def importance(self):
 433                 return self.qdom.getAttribute("importance") or Dependency.Essential
 434
 435         def get_required_commands(self):
 436                 """Return a list of command names needed by this dependency"""
 437                 return []
 438
 439 class InterfaceDependency(Dependency):
 440         """A Dependency on a Zero Install interface.
 441         @ivar interface: the interface required by this dependency
 442         @type interface: str
 443         @ivar restrictions: a list of constraints on acceptable implementations
 444         @type restrictions: [L{Restriction}]
 445         @ivar bindings: how to make the choice of implementation known
 446         @type bindings: [L{Binding}]
 447         @since: 0.28
 448         """
 449         __slots__ = ['interface', 'restrictions', 'bindings']
 450
 451         def __init__(self, interface, restrictions = None, element = None):
 452                 Dependency.__init__(self, element)
 453                 assert isinstance(interface, (str, unicode))
 454                 assert interface
 455                 self.interface = interface
 456                 if restrictions is None:
 457                         self.restrictions = []
 458                 else:
 459                         self.restrictions = restrictions
 460                 self.bindings = []
 461
 462         def __str__(self):
 463                 return _("<Dependency on %(interface)s; bindings: %(bindings)s%(restrictions)s>") % {'interface': self.interface, 'bindings': self.bindings, 'restrictions': self.restrictions}
 464
 465         def get_required_commands(self):
 466                 """Return a list of command names needed by this dependency"""
 467                 if self.qdom.name == 'runner':
 468                         commands = [self.qdom.getAttribute('command') or 'run']
 469                 else:
 470                         commands = []
 471                 for b in self.bindings:
 472                         c = b.command
 473                         if c is not None:
 474                                 commands.append(c)
 475                 return commands
 476
 477         @property
 478         def command(self):
 479                 if self.qdom.name == 'runner':
 480                         return self.qdom.getAttribute('command') or 'run'
 481                 return None
 482
 483 class RetrievalMethod(object):
 484         """A RetrievalMethod provides a way to fetch an implementation."""
 485         __slots__ = []
 486
 487 class DownloadSource(RetrievalMethod):
 488         """A DownloadSource provides a way to fetch an implementation."""
 489         __slots__ = ['implementation', 'url', 'size', 'extract', 'start_offset', 'type']
 490
 491         def __init__(self, implementation, url, size, extract, start_offset = 0, type = None):
 492                 self.implementation = implementation
 493                 self.url = url
 494                 self.size = size
 495                 self.extract = extract
 496                 self.start_offset = start_offset
 497                 self.type = type                # MIME type - see unpack.py
 498
 499 class RenameStep(RetrievalMethod):
 500         """A Rename provides a way to rename / move a file within an implementation."""
 501         __slots__ = ['source', 'dest']
 502
 503         def __init__(self, source, dest):
 504                 self.source = source
 505                 self.dest = dest
 506
 507 class Recipe(RetrievalMethod):
 508         """Get an implementation by following a series of steps.
 509         @ivar size: the combined download sizes from all the steps
 510         @type size: int
 511         @ivar steps: the sequence of steps which must be performed
 512         @type steps: [L{RetrievalMethod}]"""
 513         __slots__ = ['steps']
 514
 515         def __init__(self):
 516                 self.steps = []
 517
 518         size = property(lambda self: sum([x.size for x in self.steps if isinstance(x, DownloadSource)]))
 519
 520 class DistributionSource(RetrievalMethod):
 521         """A package that is installed using the distribution's tools (including PackageKit).
 522         @ivar install: a function to call to install this package
 523         @type install: (L{handler.Handler}) -> L{tasks.Blocker}
 524         @ivar package_id: the package name, in a form recognised by the distribution's tools
 525         @type package_id: str
 526         @ivar size: the download size in bytes
 527         @type size: int
 528         @ivar needs_confirmation: whether the user should be asked to confirm before calling install()
 529         @type needs_confirmation: bool"""
 530
 531         __slots__ = ['package_id', 'size', 'install', 'needs_confirmation']
 532
 533         def __init__(self, package_id, size, install, needs_confirmation = True):
 534                 RetrievalMethod.__init__(self)
 535                 self.package_id = package_id
 536                 self.size = size
 537                 self.install = install
 538                 self.needs_confirmation = needs_confirmation
 539
 540 class Command(object):
 541         """A Command is a way of running an Implementation as a program."""
 542
 543         __slots__ = ['qdom', '_depends', '_local_dir', '_runner', '_bindings']
 544
 545         def __init__(self, qdom, local_dir):
 546                 """@param qdom: the <command> element
 547                 @param local_dir: the directory containing the feed (for relative dependencies), or None if not local
 548                 """
 549                 assert qdom.name == 'command', 'not <command>: %s' % qdom
 550                 self.qdom = qdom
 551                 self._local_dir = local_dir
 552                 self._depends = None
 553                 self._bindings = None
 554
 555         path = property(lambda self: self.qdom.attrs.get("path", None))
 556
 557         def _toxml(self, doc, prefixes):
 558                 return self.qdom.toDOM(doc, prefixes)
 559
 560         @property
 561         def requires(self):
 562                 if self._depends is None:
 563                         self._runner = None
 564                         depends = []
 565                         for child in self.qdom.childNodes:
 566                                 if child.name == 'requires':
 567                                         dep = process_depends(child, self._local_dir)
 568                                         depends.append(dep)
 569                                 elif child.name == 'runner':
 570                                         if self._runner:
 571                                                 raise InvalidInterface(_("Multiple <runner>s in <command>!"))
 572                                         dep = process_depends(child, self._local_dir)
 573                                         depends.append(dep)
 574                                         self._runner = dep
 575                         self._depends = depends
 576                 return self._depends
 577
 578         def get_runner(self):
 579                 self.requires           # (sets _runner)
 580                 return self._runner
 581
 582         def __str__(self):
 583                 return str(self.qdom)
 584
 585         @property
 586         def bindings(self):
 587                 """@since: 1.3"""
 588                 if self._bindings is None:
 589                         bindings = []
 590                         for e in self.qdom.childNodes:
 591                                 if e.uri != XMLNS_IFACE: continue
 592                                 if e.name in binding_names:
 593                                         bindings.append(process_binding(e))
 594                         self._bindings = bindings
 595                 return self._bindings
 596
 597 class Implementation(object):
 598         """An Implementation is a package which implements an Interface.
 599         @ivar download_sources: list of methods of getting this implementation
 600         @type download_sources: [L{RetrievalMethod}]
 601         @ivar feed: the feed owning this implementation (since 0.32)
 602         @type feed: [L{ZeroInstallFeed}]
 603         @ivar bindings: how to tell this component where it itself is located (since 0.31)
 604         @type bindings: [Binding]
 605         @ivar upstream_stability: the stability reported by the packager
 606         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged]
 607         @ivar user_stability: the stability as set by the user
 608         @type upstream_stability: [insecure | buggy | developer | testing | stable | packaged | preferred]
 609         @ivar langs: natural languages supported by this package
 610         @type langs: str
 611         @ivar requires: interfaces this package depends on
 612         @type requires: [L{Dependency}]
 613         @ivar commands: ways to execute as a program
 614         @type commands: {str: Command}
 615         @ivar metadata: extra metadata from the feed
 616         @type metadata: {"[URI ]localName": str}
 617         @ivar id: a unique identifier for this Implementation
 618         @ivar version: a parsed version number
 619         @ivar released: release date
 620         @ivar local_path: the directory containing this local implementation, or None if it isn't local (id isn't a path)
 621         @type local_path: str | None
 622         @ivar requires_root_install: whether the user will need admin rights to use this
 623         @type requires_root_install: bool
 624         """
 625
 626         # Note: user_stability shouldn't really be here
 627
 628         __slots__ = ['upstream_stability', 'user_stability', 'langs',
 629                      'requires', 'metadata', 'download_sources', 'commands',
 630                      'id', 'feed', 'version', 'released', 'bindings', 'machine']
 631
 632         def __init__(self, feed, id):
 633                 assert id
 634                 self.feed = feed
 635                 self.id = id
 636                 self.user_stability = None
 637                 self.upstream_stability = None
 638                 self.metadata = {}      # [URI + " "] + localName -> value
 639                 self.requires = []
 640                 self.version = None
 641                 self.released = None
 642                 self.download_sources = []
 643                 self.langs = ""
 644                 self.machine = None
 645                 self.bindings = []
 646                 self.commands = {}
 647
 648         def get_stability(self):
 649                 return self.user_stability or self.upstream_stability or testing
 650
 651         def __str__(self):
 652                 return self.id
 653
 654         def __repr__(self):
 655                 return "v%s (%s)" % (self.get_version(), self.id)
 656
 657         def __cmp__(self, other):
 658                 """Newer versions come first"""
 659                 d = cmp(other.version, self.version)
 660                 if d: return d
 661                 # If the version number is the same, just give a stable sort order, and
 662                 # ensure that two different implementations don't compare equal.
 663                 d = cmp(other.feed.url, self.feed.url)
 664                 if d: return d
 665                 return cmp(other.id, self.id)
 666
 667         def __hash__(self):
 668                 return self.id.__hash__()
 669
 670         def __eq__(self, other):
 671                 return self is other
 672
 673         def __le__(self, other):
 674                 if isinstance(other, Implementation):
 675                         if other.version < self.version: return True
 676                         elif other.version > self.version: return False
 677
 678                         if other.feed.url < self.feed.url: return True
 679                         elif other.feed.url > self.feed.url: return False
 680
 681                         return other.id <= self.id
 682                 else:
 683                         return NotImplemented
 684
 685         def get_version(self):
 686                 """Return the version as a string.
 687                 @see: L{format_version}
 688                 """
 689                 return format_version(self.version)
 690
 691         arch = property(lambda self: _join_arch(self.os, self.machine))
 692
 693         os = None
 694         local_path = None
 695         digests = None
 696         requires_root_install = False
 697
 698         def _get_main(self):
 699                 """"@deprecated: use commands["run"] instead"""
 700                 main = self.commands.get("run", None)
 701                 if main is not None:
 702                         return main.path
 703                 return None
 704         def _set_main(self, path):
 705                 """"@deprecated: use commands["run"] instead"""
 706                 if path is None:
 707                         if "run" in self.commands:
 708                                 del self.commands["run"]
 709                 else:
 710                         self.commands["run"] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': path, 'name': 'run'}), None)
 711         main = property(_get_main, _set_main)
 712
 713         def is_available(self, stores):
 714                 """Is this Implementation available locally?
 715                 (a local implementation, an installed distribution package, or a cached ZeroInstallImplementation)
 716                 @rtype: bool
 717                 @since: 0.53
 718                 """
 719                 raise NotImplementedError("abstract")
 720
 721 class DistributionImplementation(Implementation):
 722         """An implementation provided by the distribution. Information such as the version
 723         comes from the package manager.
 724         @ivar package_implementation: the <package-implementation> element that generated this impl (since 1.7)
 725         @type package_implementation: L{qdom.Element}
 726         @since: 0.28"""
 727         __slots__ = ['distro', 'installed', 'package_implementation']
 728
 729         def __init__(self, feed, id, distro, package_implementation = None):
 730                 assert id.startswith('package:')
 731                 Implementation.__init__(self, feed, id)
 732                 self.distro = distro
 733                 self.installed = False
 734                 self.package_implementation = package_implementation
 735
 736                 if package_implementation:
 737                         for child in package_implementation.childNodes:
 738                                 if child.uri != XMLNS_IFACE: continue
 739                                 if child.name == 'command':
 740                                         command_name = child.attrs.get('name', None)
 741                                         if not command_name:
 742                                                 raise InvalidInterface('Missing name for <command>')
 743                                         self.commands[command_name] = Command(child, local_dir = None)
 744
 745         @property
 746         def requires_root_install(self):
 747                 return not self.installed
 748
 749         def is_available(self, stores):
 750                 return self.installed
 751
 752 class ZeroInstallImplementation(Implementation):
 753         """An implementation where all the information comes from Zero Install.
 754         @ivar digests: a list of "algorith=value" strings (since 0.45)
 755         @type digests: [str]
 756         @since: 0.28"""
 757         __slots__ = ['os', 'size', 'digests', 'local_path']
 758
 759         def __init__(self, feed, id, local_path):
 760                 """id can be a local path (string starting with /) or a manifest hash (eg "sha1=XXX")"""
 761                 assert not id.startswith('package:'), id
 762                 Implementation.__init__(self, feed, id)
 763                 self.size = None
 764                 self.os = None
 765                 self.digests = []
 766                 self.local_path = local_path
 767
 768         # Deprecated
 769         dependencies = property(lambda self: dict([(x.interface, x) for x in self.requires
 770                                                    if isinstance(x, InterfaceDependency)]))
 771
 772         def add_download_source(self, url, size, extract, start_offset = 0, type = None):
 773                 """Add a download source."""
 774                 self.download_sources.append(DownloadSource(self, url, size, extract, start_offset, type))
 775
 776         def set_arch(self, arch):
 777                 self.os, self.machine = _split_arch(arch)
 778         arch = property(lambda self: _join_arch(self.os, self.machine), set_arch)
 779
 780         def is_available(self, stores):
 781                 if self.local_path is not None:
 782                         return os.path.exists(self.local_path)
 783                 if self.digests:
 784                         path = stores.lookup_maybe(self.digests)
 785                         return path is not None
 786                 return False    # (0compile creates fake entries with no digests)
 787
 788 class Interface(object):
 789         """An Interface represents some contract of behaviour.
 790         @ivar uri: the URI for this interface.
 791         @ivar stability_policy: user's configured policy.
 792         Implementations at this level or higher are preferred.
 793         Lower levels are used only if there is no other choice.
 794         """
 795         __slots__ = ['uri', 'stability_policy', 'extra_feeds']
 796
 797         implementations = property(lambda self: self._main_feed.implementations)
 798         name = property(lambda self: self._main_feed.name)
 799         description = property(lambda self: self._main_feed.description)
 800         summary = property(lambda self: self._main_feed.summary)
 801         last_modified = property(lambda self: self._main_feed.last_modified)
 802         feeds = property(lambda self: self.extra_feeds + self._main_feed.feeds)
 803         metadata = property(lambda self: self._main_feed.metadata)
 804
 805         last_checked = property(lambda self: self._main_feed.last_checked)
 806
 807         def __init__(self, uri):
 808                 assert uri
 809                 if uri.startswith('http:') or uri.startswith('https:') or os.path.isabs(uri):
 810                         self.uri = uri
 811                 else:
 812                         raise SafeException(_("Interface name '%s' doesn't start "
 813                                             "with 'http:' or 'https:'") % uri)
 814                 self.reset()
 815
 816         def _get_feed_for(self):
 817                 retval = {}
 818                 for key in self._main_feed.feed_for:
 819                         retval[key] = True
 820                 return retval
 821         feed_for = property(_get_feed_for)      # Deprecated (used by 0publish)
 822
 823         def reset(self):
 824                 self.extra_feeds = []
 825                 self.stability_policy = None
 826
 827         def get_name(self):
 828                 from zeroinstall.injector.iface_cache import iface_cache
 829                 feed = iface_cache.get_feed(self.uri)
 830                 if feed:
 831                         return feed.get_name()
 832                 return '(' + os.path.basename(self.uri) + ')'
 833
 834         def __repr__(self):
 835                 return _("<Interface %s>") % self.uri
 836
 837         def set_stability_policy(self, new):
 838                 assert new is None or isinstance(new, Stability)
 839                 self.stability_policy = new
 840
 841         def get_feed(self, url):
 842                 #import warnings
 843                 #warnings.warn("use iface_cache.get_feed instead", DeprecationWarning, 2)
 844                 for x in self.extra_feeds:
 845                         if x.uri == url:
 846                                 return x
 847                 #return self._main_feed.get_feed(url)
 848                 return None
 849
 850         def get_metadata(self, uri, name):
 851                 return self._main_feed.get_metadata(uri, name)
 852
 853         @property
 854         def _main_feed(self):
 855                 #import warnings
 856                 #warnings.warn("use the feed instead", DeprecationWarning, 3)
 857                 from zeroinstall.injector import policy
 858                 iface_cache = policy.get_deprecated_singleton_config().iface_cache
 859                 feed = iface_cache.get_feed(self.uri)
 860                 if feed is None:
 861                         return _dummy_feed
 862                 return feed
 863
 864 def _merge_attrs(attrs, item):
 865         """Add each attribute of item to a copy of attrs and return the copy.
 866         @type attrs: {str: str}
 867         @type item: L{qdom.Element}
 868         @rtype: {str: str}
 869         """
 870         new = attrs.copy()
 871         for a in item.attrs:
 872                 new[str(a)] = item.attrs[a]
 873         return new
 874
 875 def _get_long(elem, attr_name):
 876         val = elem.getAttribute(attr_name)
 877         if val is not None:
 878                 try:
 879                         val = int(val)
 880                 except ValueError:
 881                         raise SafeException(_("Invalid value for integer attribute '%(attribute_name)s': %(value)s") % {'attribute_name': attr_name, 'value': val})
 882         return val
 883
 884 class ZeroInstallFeed(object):
 885         """A feed lists available implementations of an interface.
 886         @ivar url: the URL for this feed
 887         @ivar implementations: Implementations in this feed, indexed by ID
 888         @type implementations: {str: L{Implementation}}
 889         @ivar name: human-friendly name
 890         @ivar summaries: short textual description (in various languages, since 0.49)
 891         @type summaries: {str: str}
 892         @ivar descriptions: long textual description (in various languages, since 0.49)
 893         @type descriptions: {str: str}
 894         @ivar last_modified: timestamp on signature
 895         @ivar last_checked: time feed was last successfully downloaded and updated
 896         @ivar local_path: the path of this local feed, or None if remote (since 1.7)
 897         @type local_path: str | None
 898         @ivar feeds: list of <feed> elements in this feed
 899         @type feeds: [L{Feed}]
 900         @ivar feed_for: interfaces for which this could be a feed
 901         @type feed_for: set(str)
 902         @ivar metadata: extra elements we didn't understand
 903         """
 904         # _main is deprecated
 905         __slots__ = ['url', 'implementations', 'name', 'descriptions', 'first_description', 'summaries', 'first_summary', '_package_implementations',
 906                      'last_checked', 'last_modified', 'feeds', 'feed_for', 'metadata', 'local_path']
 907
 908         def __init__(self, feed_element, local_path = None, distro = None):
 909                 """Create a feed object from a DOM.
 910                 @param feed_element: the root element of a feed file
 911                 @type feed_element: L{qdom.Element}
 912                 @param local_path: the pathname of this local feed, or None for remote feeds"""
 913                 self.local_path = local_path
 914                 self.implementations = {}
 915                 self.name = None
 916                 self.summaries = {}     # { lang: str }
 917                 self.first_summary = None
 918                 self.descriptions = {}  # { lang: str }
 919                 self.first_description = None
 920                 self.last_modified = None
 921                 self.feeds = []
 922                 self.feed_for = set()
 923                 self.metadata = []
 924                 self.last_checked = None
 925                 self._package_implementations = []
 926
 927                 if distro is not None:
 928                         import warnings
 929                         warnings.warn("distro argument is now ignored", DeprecationWarning, 2)
 930
 931                 if feed_element is None:
 932                         return                  # XXX subclass?
 933
 934                 assert feed_element.name in ('interface', 'feed'), "Root element should be <interface>, not %s" % feed_element
 935                 assert feed_element.uri == XMLNS_IFACE, "Wrong namespace on root element: %s" % feed_element.uri
 936
 937                 main = feed_element.getAttribute('main')
 938                 #if main: warn("Setting 'main' on the root element is deprecated. Put it on a <group> instead")
 939
 940                 if local_path:
 941                         self.url = local_path
 942                         local_dir = os.path.dirname(local_path)
 943                 else:
 944                         assert local_path is None
 945                         self.url = feed_element.getAttribute('uri')
 946                         if not self.url:
 947                                 raise InvalidInterface(_("<interface> uri attribute missing"))
 948                         local_dir = None        # Can't have relative paths
 949
 950                 min_injector_version = feed_element.getAttribute('min-injector-version')
 951                 if min_injector_version:
 952                         if parse_version(min_injector_version) > parse_version(version):
 953                                 raise InvalidInterface(_("This feed requires version %(min_version)s or later of "
 954                                                         "Zero Install, but I am only version %(version)s. "
 955                                                         "You can get a newer version from http://0install.net") %
 956                                                         {'min_version': min_injector_version, 'version': version})
 957
 958                 for x in feed_element.childNodes:
 959                         if x.uri != XMLNS_IFACE:
 960                                 self.metadata.append(x)
 961                                 continue
 962                         if x.name == 'name':
 963                                 self.name = x.content
 964                         elif x.name == 'description':
 965                                 if self.first_description == None:
 966                                         self.first_description = x.content
 967                                 self.descriptions[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 968                         elif x.name == 'summary':
 969                                 if self.first_summary == None:
 970                                         self.first_summary = x.content
 971                                 self.summaries[x.attrs.get("http://www.w3.org/XML/1998/namespace lang", 'en')] = x.content
 972                         elif x.name == 'feed-for':
 973                                 feed_iface = x.getAttribute('interface')
 974                                 if not feed_iface:
 975                                         raise InvalidInterface(_('Missing "interface" attribute in <feed-for>'))
 976                                 self.feed_for.add(feed_iface)
 977                                 # Bug report from a Debian/stable user that --feed gets the wrong value.
 978                                 # Can't reproduce (even in a Debian/stable chroot), but add some logging here
 979                                 # in case it happens again.
 980                                 debug(_("Is feed-for %s"), feed_iface)
 981                         elif x.name == 'feed':
 982                                 feed_src = x.getAttribute('src')
 983                                 if not feed_src:
 984                                         raise InvalidInterface(_('Missing "src" attribute in <feed>'))
 985                                 if feed_src.startswith('http:') or feed_src.startswith('https:') or local_path:
 986                                         langs = x.getAttribute('langs')
 987                                         if langs: langs = langs.replace('_', '-')
 988                                         self.feeds.append(Feed(feed_src, x.getAttribute('arch'), False, langs = langs))
 989                                 else:
 990                                         raise InvalidInterface(_("Invalid feed URL '%s'") % feed_src)
 991                         else:
 992                                 self.metadata.append(x)
 993
 994                 if not self.name:
 995                         raise InvalidInterface(_("Missing <name> in feed"))
 996                 if not self.summary:
 997                         raise InvalidInterface(_("Missing <summary> in feed"))
 998
 999                 def process_group(group, group_attrs, base_depends, base_bindings, base_commands):
1000                         for item in group.childNodes:
1001                                 if item.uri != XMLNS_IFACE: continue
1002
1003                                 if item.name not in ('group', 'implementation', 'package-implementation'):
1004                                         continue
1005
1006                                 # We've found a group or implementation. Scan for dependencies,
1007                                 # bindings and commands. Doing this here means that:
1008                                 # - We can share the code for groups and implementations here.
1009                                 # - The order doesn't matter, because these get processed first.
1010                                 # A side-effect is that the document root cannot contain
1011                                 # these.
1012
1013                                 depends = base_depends[:]
1014                                 bindings = base_bindings[:]
1015                                 commands = base_commands.copy()
1016
1017                                 for attr, command in [('main', 'run'),
1018                                                       ('self-test', 'test')]:
1019                                         value = item.attrs.get(attr, None)
1020                                         if value is not None:
1021                                                 commands[command] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': command, 'path': value}), None)
1022
1023                                 for child in item.childNodes:
1024                                         if child.uri != XMLNS_IFACE: continue
1025                                         if child.name == 'requires':
1026                                                 dep = process_depends(child, local_dir)
1027                                                 depends.append(dep)
1028                                         elif child.name == 'command':
1029                                                 command_name = child.attrs.get('name', None)
1030                                                 if not command_name:
1031                                                         raise InvalidInterface('Missing name for <command>')
1032                                                 commands[command_name] = Command(child, local_dir)
1033                                         elif child.name in binding_names:
1034                                                 bindings.append(process_binding(child))
1035
1036                                 compile_command = item.attrs.get('http://zero-install.sourceforge.net/2006/namespaces/0compile command')
1037                                 if compile_command is not None:
1038                                         commands['compile'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'name': 'compile', 'shell-command': compile_command}), None)
1039
1040                                 item_attrs = _merge_attrs(group_attrs, item)
1041
1042                                 if item.name == 'group':
1043                                         process_group(item, item_attrs, depends, bindings, commands)
1044                                 elif item.name == 'implementation':
1045                                         process_impl(item, item_attrs, depends, bindings, commands)
1046                                 elif item.name == 'package-implementation':
1047                                         if depends:
1048                                                 warn("A <package-implementation> with dependencies in %s!", self.url)
1049                                         self._package_implementations.append((item, item_attrs))
1050                                 else:
1051                                         assert 0
1052
1053                 def process_impl(item, item_attrs, depends, bindings, commands):
1054                         id = item.getAttribute('id')
1055                         if id is None:
1056                                 raise InvalidInterface(_("Missing 'id' attribute on %s") % item)
1057                         local_path = item_attrs.get('local-path')
1058                         if local_dir and local_path:
1059                                 abs_local_path = os.path.abspath(os.path.join(local_dir, local_path))
1060                                 impl = ZeroInstallImplementation(self, id, abs_local_path)
1061                         elif local_dir and (id.startswith('/') or id.startswith('.')):
1062                                 # For old feeds
1063                                 id = os.path.abspath(os.path.join(local_dir, id))
1064                                 impl = ZeroInstallImplementation(self, id, id)
1065                         else:
1066                                 impl = ZeroInstallImplementation(self, id, None)
1067                                 if '=' in id:
1068                                         # In older feeds, the ID was the (single) digest
1069                                         impl.digests.append(id)
1070                         if id in self.implementations:
1071                                 warn(_("Duplicate ID '%(id)s' in feed '%(feed)s'"), {'id': id, 'feed': self})
1072                         self.implementations[id] = impl
1073
1074                         impl.metadata = item_attrs
1075                         try:
1076                                 version_mod = item_attrs.get('version-modifier', None)
1077                                 if version_mod:
1078                                         item_attrs['version'] += version_mod
1079                                         del item_attrs['version-modifier']
1080                                 version = item_attrs['version']
1081                         except KeyError:
1082                                 raise InvalidInterface(_("Missing version attribute"))
1083                         impl.version = parse_version(version)
1084
1085                         impl.commands = commands
1086
1087                         impl.released = item_attrs.get('released', None)
1088                         impl.langs = item_attrs.get('langs', '').replace('_', '-')
1089
1090                         size = item.getAttribute('size')
1091                         if size:
1092                                 impl.size = int(size)
1093                         impl.arch = item_attrs.get('arch', None)
1094                         try:
1095                                 stability = stability_levels[str(item_attrs['stability'])]
1096                         except KeyError:
1097                                 stab = str(item_attrs['stability'])
1098                                 if stab != stab.lower():
1099                                         raise InvalidInterface(_('Stability "%s" invalid - use lower case!') % item_attrs.stability)
1100                                 raise InvalidInterface(_('Stability "%s" invalid') % item_attrs['stability'])
1101                         if stability >= preferred:
1102                                 raise InvalidInterface(_("Upstream can't set stability to preferred!"))
1103                         impl.upstream_stability = stability
1104
1105                         impl.bindings = bindings
1106                         impl.requires = depends
1107
1108                         for elem in item.childNodes:
1109                                 if elem.uri != XMLNS_IFACE: continue
1110                                 if elem.name == 'archive':
1111                                         url = elem.getAttribute('href')
1112                                         if not url:
1113                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1114                                         size = elem.getAttribute('size')
1115                                         if not size:
1116                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1117                                         impl.add_download_source(url = url, size = int(size),
1118                                                         extract = elem.getAttribute('extract'),
1119                                                         start_offset = _get_long(elem, 'start-offset'),
1120                                                         type = elem.getAttribute('type'))
1121                                 elif elem.name == 'manifest-digest':
1122                                         for aname, avalue in elem.attrs.items():
1123                                                 if ' ' not in aname:
1124                                                         impl.digests.append('%s=%s' % (aname, avalue))
1125                                 elif elem.name == 'recipe':
1126                                         recipe = Recipe()
1127                                         for recipe_step in elem.childNodes:
1128                                                 if recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'archive':
1129                                                         url = recipe_step.getAttribute('href')
1130                                                         if not url:
1131                                                                 raise InvalidInterface(_("Missing href attribute on <archive>"))
1132                                                         size = recipe_step.getAttribute('size')
1133                                                         if not size:
1134                                                                 raise InvalidInterface(_("Missing size attribute on <archive>"))
1135                                                         recipe.steps.append(DownloadSource(None, url = url, size = int(size),
1136                                                                         extract = recipe_step.getAttribute('extract'),
1137                                                                         start_offset = _get_long(recipe_step, 'start-offset'),
1138                                                                         type = recipe_step.getAttribute('type')))
1139                                                 elif recipe_step.uri == XMLNS_IFACE and recipe_step.name == 'rename':
1140                                                         source = recipe_step.getAttribute('source')
1141                                                         if not source:
1142                                                                 raise InvalidInterface(_("Missing source attribute on <rename>"))
1143                                                         dest = recipe_step.getAttribute('dest')
1144                                                         if not dest:
1145                                                                 raise InvalidInterface(_("Missing dest attribute on <rename>"))
1146                                                         recipe.steps.append(RenameStep(source=source, dest=dest))
1147                                                 else:
1148                                                         info(_("Unknown step '%s' in recipe; skipping recipe"), recipe_step.name)
1149                                                         break
1150                                         else:
1151                                                 impl.download_sources.append(recipe)
1152
1153                 root_attrs = {'stability': 'testing'}
1154                 root_commands = {}
1155                 if main:
1156                         info("Note: @main on document element is deprecated in %s", self)
1157                         root_commands['run'] = Command(qdom.Element(XMLNS_IFACE, 'command', {'path': main, 'name': 'run'}), None)
1158                 process_group(feed_element, root_attrs, [], [], root_commands)
1159
1160         def get_distro_feed(self):
1161                 """Does this feed contain any <pacakge-implementation> elements?
1162                 i.e. is it worth asking the package manager for more information?
1163                 @return: the URL of the virtual feed, or None
1164                 @since: 0.49"""
1165                 if self._package_implementations:
1166                         return "distribution:" + self.url
1167                 return None
1168
1169         def get_package_impls(self, distro):
1170                 """Find the best <pacakge-implementation> element(s) for the given distribution.
1171                 @param distro: the distribution to use to rate them
1172                 @type distro: L{distro.Distribution}
1173                 @return: a list of tuples for the best ranked elements
1174                 @rtype: [str]
1175                 @since: 0.49"""
1176                 best_score = 0
1177                 best_impls = []
1178
1179                 for item, item_attrs in self._package_implementations:
1180                         distro_names = item_attrs.get('distributions', '')
1181                         added_this = False
1182                         for distro_name in distro_names.split(' '):
1183                                 score = distro.get_score(distro_name) if distro_name else 0.5
1184                                 if score > best_score:
1185                                         best_score = score
1186                                         best_impls = []
1187                                 if score == best_score and not added_this:
1188                                         best_impls.append((item, item_attrs))
1189                                         added_this = True
1190                 return best_impls
1191
1192         def get_name(self):
1193                 return self.name or '(' + os.path.basename(self.url) + ')'
1194
1195         def __repr__(self):
1196                 return _("<Feed %s>") % self.url
1197
1198         def set_stability_policy(self, new):
1199                 assert new is None or isinstance(new, Stability)
1200                 self.stability_policy = new
1201
1202         def get_feed(self, url):
1203                 for x in self.feeds:
1204                         if x.uri == url:
1205                                 return x
1206                 return None
1207
1208         def add_metadata(self, elem):
1209                 self.metadata.append(elem)
1210
1211         def get_metadata(self, uri, name):
1212                 """Return a list of interface metadata elements with this name and namespace URI."""
1213                 return [m for m in self.metadata if m.name == name and m.uri == uri]
1214
1215         @property
1216         def summary(self):
1217                 return _best_language_match(self.summaries) or self.first_summary
1218
1219         @property
1220         def description(self):
1221                 return _best_language_match(self.descriptions) or self.first_description
1222
1223         def get_replaced_by(self):
1224                 """Return the URI of the interface that replaced the one with the URI of this feed's URL.
1225                 This is the value of the feed's <replaced-by interface'...'/> element.
1226                 @return: the new URI, or None if it hasn't been replaced
1227                 @since: 1.7"""
1228                 for child in self.metadata:
1229                         if child.uri == XMLNS_IFACE and child.name == 'replaced-by':
1230                                 new_uri = child.getAttribute('interface')
1231                                 if new_uri and (new_uri.startswith('http:') or new_uri.startswith('https:') or self.local_path):
1232                                         return new_uri
1233                 return None
1234
1235 class DummyFeed(object):
1236         """Temporary class used during API transition."""
1237         last_modified = None
1238         name = '-'
1239         last_checked = property(lambda self: None)
1240         implementations = property(lambda self: {})
1241         feeds = property(lambda self: [])
1242         summary = property(lambda self: '-')
1243         description = property(lambda self: '')
1244         def get_name(self): return self.name
1245         def get_feed(self, url): return None
1246         def get_metadata(self, uri, name): return []
1247 _dummy_feed = DummyFeed()
1248
1249 if sys.version_info[0] > 2:
1250         # Python 3
1251         from functools import total_ordering
1252         Stability = total_ordering(Stability)
1253         Implementation = total_ordering(Implementation)
1254
1255         unicode = str
1256         basestring = str
1257         intern = sys.intern
1258
1259         # These could be replaced by urllib.parse.quote, except that
1260         # it uses upper-case escapes and we use lower-case ones...
1261         def unescape(uri):
1262                 """Convert each %20 to a space, etc.
1263                 @rtype: str"""
1264                 uri = uri.replace('#', '/')
1265                 if '%' not in uri: return uri
1266                 return re.sub(b'%[0-9a-fA-F][0-9a-fA-F]',
1267                         lambda match: bytes([int(match.group(0)[1:], 16)]),
1268                         uri.encode('ascii')).decode('utf-8')
1269
1270         def escape(uri):
1271                 """Convert each space to %20, etc
1272                 @rtype: str"""
1273                 return re.sub(b'[^-_.a-zA-Z0-9]',
1274                         lambda match: ('%%%02x' % ord(match.group(0))).encode('ascii'),
1275                         uri.encode('utf-8')).decode('ascii')
1276
1277         def _pretty_escape(uri):
1278                 """Convert each space to %20, etc
1279                 : is preserved and / becomes #. This makes for nicer strings,
1280                 and may replace L{escape} everywhere in future.
1281                 @rtype: str"""
1282                 if os.name == "posix":
1283                         # Only preserve : on Posix systems
1284                         preserveRegex = b'[^-_.a-zA-Z0-9:/]'
1285                 else:
1286                         # Other OSes may not allow the : character in file names
1287                         preserveRegex = b'[^-_.a-zA-Z0-9/]'
1288                 return re.sub(preserveRegex,
1289                         lambda match: ('%%%02x' % ord(match.group(0))).encode('ascii'),
1290                         uri.encode('utf-8')).decode('ascii').replace('/', '#')
1291 else:
1292         # Python 2
1293         unicode = unicode               # (otherwise it can't be imported)
1294         basestring = basestring
1295         intern = intern
1296
1297         def unescape(uri):
1298                 """Convert each %20 to a space, etc.
1299                 @rtype: str"""
1300                 uri = uri.replace('#', '/')
1301                 if '%' not in uri: return uri
1302                 return re.sub('%[0-9a-fA-F][0-9a-fA-F]',
1303                         lambda match: chr(int(match.group(0)[1:], 16)),
1304                         uri).decode('utf-8')
1305
1306         def escape(uri):
1307                 """Convert each space to %20, etc
1308                 @rtype: str"""
1309                 return re.sub('[^-_.a-zA-Z0-9]',
1310                         lambda match: '%%%02x' % ord(match.group(0)),
1311                         uri.encode('utf-8'))
1312
1313         def _pretty_escape(uri):
1314                 """Convert each space to %20, etc
1315                 : is preserved and / becomes #. This makes for nicer strings,
1316                 and may replace L{escape} everywhere in future.
1317                 @rtype: str"""
1318                 if os.name == "posix":
1319                         # Only preserve : on Posix systems
1320                         preserveRegex = '[^-_.a-zA-Z0-9:/]'
1321                 else:
1322                         # Other OSes may not allow the : character in file names
1323                         preserveRegex = '[^-_.a-zA-Z0-9/]'
1324                 return re.sub(preserveRegex,
1325                         lambda match: '%%%02x' % ord(match.group(0)),
1326                         uri.encode('utf-8')).replace('/', '#')
1327
1328 def canonical_iface_uri(uri):
1329         """If uri is a relative path, convert to an absolute one.
1330         A "file:///foo" URI is converted to "/foo".
1331         An "alias:prog" URI expands to the URI in the 0alias script
1332         Otherwise, return it unmodified.
1333         @rtype: str
1334         @raise SafeException: if uri isn't valid
1335         """
1336         if uri.startswith('http://') or uri.startswith('https://'):
1337                 if uri.count("/") < 3:
1338                         raise SafeException(_("Missing / after hostname in URI '%s'") % uri)
1339                 return uri
1340         elif uri.startswith('file:///'):
1341                 path = uri[7:]
1342         elif uri.startswith('file:'):
1343                 if uri[5] == '/':
1344                         raise SafeException(_('Use file:///path for absolute paths, not {uri}').format(uri = uri))
1345                 path = os.path.abspath(uri[5:])
1346         elif uri.startswith('alias:'):
1347                 from zeroinstall import alias, support
1348                 alias_prog = uri[6:]
1349                 if not os.path.isabs(alias_prog):
1350                         full_path = support.find_in_path(alias_prog)
1351                         if not full_path:
1352                                 raise alias.NotAnAliasScript("Not found in $PATH: " + alias_prog)
1353                 else:
1354                         full_path = alias_prog
1355                 return alias.parse_script(full_path).uri
1356         else:
1357                 path = os.path.realpath(uri)
1358
1359         if os.path.isfile(path):
1360                 return path
1361         raise SafeException(_("Bad interface name '%(uri)s'.\n"
1362                         "(doesn't start with 'http:', and "
1363                         "doesn't exist as a local file '%(interface_uri)s' either)") %
1364                         {'uri': uri, 'interface_uri': path})
1365
1366 _version_mod_to_value = {
1367         'pre': -2,
1368         'rc': -1,
1369         '': 0,
1370         'post': 1,
1371 }
1372
1373 # Reverse mapping
1374 _version_value_to_mod = {}
1375 for x in _version_mod_to_value: _version_value_to_mod[_version_mod_to_value[x]] = x
1376 del x
1377
1378 _version_re = re.compile('-([a-z]*)')
1379
1380 def parse_version(version_string):
1381         """Convert a version string to an internal representation.
1382         The parsed format can be compared quickly using the standard Python functions.
1383          - Version := DottedList ("-" Mod DottedList?)*
1384          - DottedList := (Integer ("." Integer)*)
1385         @rtype: tuple (opaque)
1386         @raise SafeException: if the string isn't a valid version
1387         @since: 0.24 (moved from L{reader}, from where it is still available):"""
1388         if version_string is None: return None
1389         parts = _version_re.split(version_string)
1390         if parts[-1] == '':
1391                 del parts[-1]   # Ends with a modifier
1392         else:
1393                 parts.append('')
1394         if not parts:
1395                 raise SafeException(_("Empty version string!"))
1396         l = len(parts)
1397         try:
1398                 for x in range(0, l, 2):
1399                         part = parts[x]
1400                         if part:
1401                                 parts[x] = list(map(int, parts[x].split('.')))
1402                         else:
1403                                 parts[x] = []   # (because ''.split('.') == [''], not [])
1404                 for x in range(1, l, 2):
1405                         parts[x] = _version_mod_to_value[parts[x]]
1406                 return parts
1407         except ValueError as ex:
1408                 raise SafeException(_("Invalid version format in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1409         except KeyError as ex:
1410                 raise SafeException(_("Invalid version modifier in '%(version_string)s': %(exception)s") % {'version_string': version_string, 'exception': ex})
1411
1412 def format_version(version):
1413         """Format a parsed version for display. Undoes the effect of L{parse_version}.
1414         @see: L{Implementation.get_version}
1415         @rtype: str
1416         @since: 0.24"""
1417         version = version[:]
1418         l = len(version)
1419         for x in range(0, l, 2):
1420                 version[x] = '.'.join(map(str, version[x]))
1421         for x in range(1, l, 2):
1422                 version[x] = '-' + _version_value_to_mod[version[x]]
1423         if version[-1] == '-': del version[-1]
1424         return ''.join(version)
1425