text: # -*- coding: utf-8 -*-
  """
      werkzeug.urls
      ~~~~~~~~~~~~~
  
      ``werkzeug.urls`` used to provide several wrapper functions for Python 2
      urlparse, whose main purpose were to work around the behavior of the Py2
      stdlib and its lack of unicode support. While this was already a somewhat
      inconvenient situation, it got even more complicated because Python 3's
      ``urllib.parse`` actually does handle unicode properly. In other words,
      this module would wrap two libraries with completely different behavior. So
      now this module contains a 2-and-3-compatible backport of Python 3's
      ``urllib.parse``, which is mostly API-compatible.
  
      :copyright: (c) 2014 by the Werkzeug Team, see AUTHORS for more details.
      :license: BSD, see LICENSE for more details.
  """
  from collections import namedtuple
  
  import codecs
  import os
  import re
  
  from werkzeug._compat import (
      PY2,
      fix_tuple_repr,
      implements_to_string,
      make_literal_wrapper,
      normalize_string_tuple,
      text_type,
      to_native,
      to_unicode,
      try_coerce_native,
  )
  from werkzeug._internal import _decode_idna, _encode_idna
  from werkzeug.datastructures import MultiDict, iter_multi_items
  
  # A regular expression for what a valid schema looks like
  _scheme_re = re.compile(r'^[a-zA-Z0-9+-.]+$')
  
  # Characters that are safe in any part of an URL.
  _always_safe = frozenset(bytearray(
      b"abcdefghijklmnopqrstuvwxyz"
      b"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
      b"0123456789"
      b"-._~"
  ))
  
  _hexdigits = '0123456789ABCDEFabcdef'
  _hextobyte = dict(
      ((a + b).encode(), int(a + b, 16))
      for a in _hexdigits for b in _hexdigits
  )
  _bytetohex = [
      ('%%%02X' % char).encode('ascii') for char in range(256)
  ]
  
  
  _URLTuple = fix_tuple_repr(namedtuple(
      '_URLTuple',
      ['scheme', 'netloc', 'path', 'query', 'fragment']
  ))
  
  
  class BaseURL(_URLTuple):
  
      '''Superclass of :py:class:`URL` and :py:class:`BytesURL`.'''
      __slots__ = ()
  
      def replace(self, **kwargs):
          """Return an URL with the same values, except for those parameters
          given new values by whichever keyword arguments are specified."""
          return self._replace(**kwargs)
  
      @property
      def host(self):
          """The host part of the URL if available, otherwise `None`.  The
          host is either the hostname or the IP address mentioned in the
          URL.  It will not contain the port.
          """
          return self._split_host()[0]
  
      @property
      def ascii_host(self):
          """Works exactly like :attr:`host` but will return a result that
          is restricted to ASCII.  If it finds a netloc that is not ASCII
          it will attempt to idna decode it.  This is useful for socket
          operations when the URL might include internationalized characters.
          """
          rv = self.host
          if rv is not None and isinstance(rv, text_type):
              try:
                  rv = _encode_idna(rv)
              except UnicodeError:
                  rv = rv.encode('ascii', 'ignore')
          return to_native(rv, 'ascii', 'ignore')
  
      @property
      def port(self):
          """The port in the URL as an integer if it was present, `None`
          otherwise.  This does not fill in default ports.
          """
          try:
              rv = int(to_native(self._split_host()[1]))
              if 0 <= rv <= 65535:
                  return rv
          except (ValueError, TypeError):
              pass
  
      @property
      def auth(self):
          """The authentication part in the URL if available, `None`
          otherwise.
          """
          return self._split_netloc()[0]
  
      @property
      def username(self):
          """The username if it was part of the URL, `None` otherwise.
          This undergoes URL decoding and will always be a unicode string.
          """
          rv = self._split_auth()[0]
          if rv is not None:
              return _url_unquote_legacy(rv)
  
      @property
      def raw_username(self):
          """The username if it was part of the URL, `None` otherwise.
          Unlike :attr:`username` this one is not being decoded.
          """
          return self._split_auth()[0]
  
      @property
      def password(self):
          """The password if it was part of the URL, `None` otherwise.
          This undergoes URL decoding and will always be a unicode string.
          """
          rv = self._split_auth()[1]
          if rv is not None:
              return _url_unquote_legacy(rv)
  
      @property
      def raw_password(self):
          """The password if it was part of the URL, `None` otherwise.
          Unlike :attr:`password` this one is not being decoded.
          """
          return self._split_auth()[1]
  
      def decode_query(self, *args, **kwargs):
          """Decodes the query part of the URL.  Ths is a shortcut for
          calling :func:`url_decode` on the query argument.  The arguments and
          keyword arguments are forwarded to :func:`url_decode` unchanged.
          """
          return url_decode(self.query, *args, **kwargs)
  
      def join(self, *args, **kwargs):
          """Joins this URL with another one.  This is just a convenience
          function for calling into :meth:`url_join` and then parsing the
          return value again.
          """
          return url_parse(url_join(self, *args, **kwargs))
  
      def to_url(self):
          """Returns a URL string or bytes depending on the type of the
          information stored.  This is just a convenience function
          for calling :meth:`url_unparse` for this URL.
          """
          return url_unparse(self)
  
      def decode_netloc(self):
          """Decodes the netloc part into a string."""
          rv = _decode_idna(self.host or '')
  
          if ':' in rv:
              rv = '[%s]' % rv
          port = self.port
          if port is not None:
              rv = '%s:%d' % (rv, port)
          auth = ':'.join(filter(None, [
              _url_unquote_legacy(self.raw_username or '', '/:%@'),
              _url_unquote_legacy(self.raw_password or '', '/:%@'),
          ]))
          if auth:
              rv = '%s@%s' % (auth, rv)
          return rv
  
      def to_uri_tuple(self):
          """Returns a :class:`BytesURL` tuple that holds a URI.  This will
          encode all the information in the URL properly to ASCII using the
          rules a web browser would follow.
  
          It's usually more interesting to directly call :meth:`iri_to_uri` which
          will return a string.
          """
          return url_parse(iri_to_uri(self).encode('ascii'))
  
      def to_iri_tuple(self):
          """Returns a :class:`URL` tuple that holds a IRI.  This will try
          to decode as much information as possible in the URL without
          losing information similar to how a web browser does it for the
          URL bar.
  
          It's usually more interesting to directly call :meth:`uri_to_iri` which
          will return a string.
          """
          return url_parse(uri_to_iri(self))
  
      def get_file_location(self, pathformat=None):
          """Returns a tuple with the location of the file in the form
          ``(server, location)``.  If the netloc is empty in the URL or
          points to localhost, it's represented as ``None``.
  
          The `pathformat` by default is autodetection but needs to be set
          when working with URLs of a specific system.  The supported values
          are ``'windows'`` when working with Windows or DOS paths and
          ``'posix'`` when working with posix paths.
  
          If the URL does not point to a local file, the server and location
          are both represented as ``None``.
  
          :param pathformat: The expected format of the path component.
                             Currently ``'windows'`` and ``'posix'`` are
                             supported.  Defaults to ``None`` which is
                             autodetect.
          """
          if self.scheme != 'file':
              return None, None
  
          path = url_unquote(self.path)
          host = self.netloc or None
  
          if pathformat is None:
              if os.name == 'nt':
                  pathformat = 'windows'
              else:
                  pathformat = 'posix'
  
          if pathformat == 'windows':
              if path[:1] == '/' and path[1:2].isalpha() and path[2:3] in '|:':
                  path = path[1:2] + ':' + path[3:]
              windows_share = path[:3] in ('\\' * 3, '/' * 3)
              import ntpath
              path = ntpath.normpath(path)
              # Windows shared drives are represented as ``\\host\\directory``.
              # That results in a URL like ``file://///host/directory``, and a
              # path like ``///host/directory``. We need to special-case this
              # because the path contains the hostname.
              if windows_share and host is None:
                  parts = path.lstrip('\\').split('\\', 1)
                  if len(parts) == 2:
                      host, path = parts
                  else:
                      host = parts[0]
                      path = ''
          elif pathformat == 'posix':
              import posixpath
              path = posixpath.normpath(path)
          else:
              raise TypeError('Invalid path format %s' % repr(pathformat))
  
          if host in ('127.0.0.1', '::1', 'localhost'):
              host = None
  
          return host, path
  
      def _split_netloc(self):
          if self._at in self.netloc:
              return self.netloc.split(self._at, 1)
          return None, self.netloc
  
      def _split_auth(self):
          auth = self._split_netloc()[0]
          if not auth:
              return None, None
          if self._colon not in auth:
              return auth, None
          return auth.split(self._colon, 1)
  
      def _split_host(self):
          rv = self._split_netloc()[1]
          if not rv:
              return None, None
  
          if not rv.startswith(self._lbracket):
              if self._colon in rv:
                  return rv.split(self._colon, 1)
              return rv, None
  
          idx = rv.find(self._rbracket)
          if idx < 0:
              return rv, None
  
          host = rv[1:idx]
          rest = rv[idx + 1:]
          if rest.startswith(self._colon):
              return host, rest[1:]
          return host, None
  
  
  @implements_to_string
  class URL(BaseURL):
  
      """Represents a parsed URL.  This behaves like a regular tuple but
      also has some extra attributes that give further insight into the
      URL.
      """
      __slots__ = ()
      _at = '@'
      _colon = ':'
      _lbracket = '['
      _rbracket = ']'
  
      def __str__(self):
          return self.to_url()
  
      def encode_netloc(self):
          """Encodes the netloc part to an ASCII safe URL as bytes."""
          rv = self.ascii_host or ''
          if ':' in rv:
              rv = '[%s]' % rv
          port = self.port
          if port is not None:
              rv = '%s:%d' % (rv, port)
          auth = ':'.join(filter(None, [
              url_quote(self.raw_username or '', 'utf-8', 'strict', '/:%'),
              url_quote(self.raw_password or '', 'utf-8', 'strict', '/:%'),
          ]))
          if auth:
              rv = '%s@%s' % (auth, rv)
          return to_native(rv)
  
      def encode(self, charset='utf-8', errors='replace'):
          """Encodes the URL to a tuple made out of bytes.  The charset is
          only being used for the path, query and fragment.
          """
          return BytesURL(
              self.scheme.encode('ascii'),
              self.encode_netloc(),
              self.path.encode(charset, errors),
              self.query.encode(charset, errors),
              self.fragment.encode(charset, errors)
          )
  
  
  class BytesURL(BaseURL):
  
      """Represents a parsed URL in bytes."""
      __slots__ = ()
      _at = b'@'
      _colon = b':'
      _lbracket = b'['
      _rbracket = b']'
  
      def __str__(self):
          return self.to_url().decode('utf-8', 'replace')
  
      def encode_netloc(self):
          """Returns the netloc unchanged as bytes."""
          return self.netloc
  
      def decode(self, charset='utf-8', errors='replace'):
          """Decodes the URL to a tuple made out of strings.  The charset is
          only being used for the path, query and fragment.
          """
          return URL(
              self.scheme.decode('ascii'),
              self.decode_netloc(),
              self.path.decode(charset, errors),
              self.query.decode(charset, errors),
              self.fragment.decode(charset, errors)
          )
  
  
  _unquote_maps = {
      frozenset(): _hextobyte,
  }
  
  
  def _unquote_to_bytes(string, unsafe=""):
      if isinstance(string, text_type):
          string = string.encode("utf-8")
  
      if isinstance(unsafe, text_type):
          unsafe = unsafe.encode("utf-8")
  
      unsafe = frozenset(bytearray(unsafe))
      groups = iter(string.split(b"%"))
      result = bytearray(next(groups, b""))
  
      try:
          hex_to_byte = _unquote_maps[unsafe]
      except KeyError:
          hex_to_byte = _unquote_maps[unsafe] = {
              h: b for h, b in _hextobyte.items() if b not in unsafe
          }
  
      for group in groups:
          code = group[:2]
  
          if code in hex_to_byte:
              result.append(hex_to_byte[code])
              result.extend(group[2:])
          else:
              result.append(37)  # %
              result.extend(group)
  
      return bytes(result)
  
  
  def _url_encode_impl(obj, charset, encode_keys, sort, key):
      iterable = iter_multi_items(obj)
      if sort:
          iterable = sorted(iterable, key=key)
      for key, value in iterable:
          if value is None:
              continue
          if not isinstance(key, bytes):
              key = text_type(key).encode(charset)
          if not isinstance(value, bytes):
              value = text_type(value).encode(charset)
          yield _fast_url_quote_plus(key) + '=' + _fast_url_quote_plus(value)
  
  
  def _url_unquote_legacy(value, unsafe=''):
      try:
          return url_unquote(value, charset='utf-8',
                             errors='strict', unsafe=unsafe)
      except UnicodeError:
          return url_unquote(value, charset='latin1', unsafe=unsafe)
  
  
  def url_parse(url, scheme=None, allow_fragments=True):
      """Parses a URL from a string into a :class:`URL` tuple.  If the URL
      is lacking a scheme it can be provided as second argument. Otherwise,
      it is ignored.  Optionally fragments can be stripped from the URL
      by setting `allow_fragments` to `False`.
  
      The inverse of this function is :func:`url_unparse`.
  
      :param url: the URL to parse.
      :param scheme: the default schema to use if the URL is schemaless.
      :param allow_fragments: if set to `False` a fragment will be removed
                              from the URL.
      """
      s = make_literal_wrapper(url)
      is_text_based = isinstance(url, text_type)
  
      if scheme is None:
          scheme = s('')
      netloc = query = fragment = s('')
      i = url.find(s(':'))
      if i > 0 and _scheme_re.match(to_native(url[:i], errors='replace')):
          # make sure "iri" is not actually a port number (in which case
          # "scheme" is really part of the path)
          rest = url[i + 1:]
          if not rest or any(c not in s('0123456789') for c in rest):
              # not a port number
              scheme, url = url[:i].lower(), rest
  
      if url[:2] == s('//'):
          delim = len(url)
          for c in s('/?#'):
              wdelim = url.find(c, 2)
              if wdelim >= 0:
                  delim = min(delim, wdelim)
          netloc, url = url[2:delim], url[delim:]
          if (s('[') in netloc and s(']') not in netloc) or \
             (s(']') in netloc and s('[') not in netloc):
              raise ValueError('Invalid IPv6 URL')
  
      if allow_fragments and s('#') in url:
          url, fragment = url.split(s('#'), 1)
      if s('?') in url:
          url, query = url.split(s('?'), 1)
  
      result_type = URL if is_text_based else BytesURL
      return result_type(scheme, netloc, url, query, fragment)
  
  
  def _make_fast_url_quote(charset='utf-8', errors='strict', safe='/:', unsafe=''):
      """Precompile the translation table for a URL encoding function.
  
      Unlike :func:`url_quote`, the generated function only takes the
      string to quote.
  
      :param charset: The charset to encode the result with.
      :param errors: How to handle encoding errors.
      :param safe: An optional sequence of safe characters to never encode.
      :param unsafe: An optional sequence of unsafe characters to always encode.
      """
      if isinstance(safe, text_type):
          safe = safe.encode(charset, errors)
  
      if isinstance(unsafe, text_type):
          unsafe = unsafe.encode(charset, errors)
  
      safe = (frozenset(bytearray(safe)) | _always_safe) - frozenset(bytearray(unsafe))
      table = [chr(c) if c in safe else '%%%02X' % c for c in range(256)]
  
      if not PY2:
          def quote(string):
              return "".join([table[c] for c in string])
      else:
          def quote(string):
              return "".join([table[c] for c in bytearray(string)])
  
      return quote
  
  
  _fast_url_quote = _make_fast_url_quote()
  _fast_quote_plus = _make_fast_url_quote(safe=' ', unsafe='+')
  
  
  def _fast_url_quote_plus(string):
      return _fast_quote_plus(string).replace(' ', '+')
  
  
  def url_quote(string, charset='utf-8', errors='strict', safe='/:', unsafe=''):
      """URL encode a single string with a given encoding.
  
      :param s: the string to quote.
      :param charset: the charset to be used.
      :param safe: an optional sequence of safe characters.
      :param unsafe: an optional sequence of unsafe characters.
  
      .. versionadded:: 0.9.2
         The `unsafe` parameter was added.
      """
      if not isinstance(string, (text_type, bytes, bytearray)):
          string = text_type(string)
      if isinstance(string, text_type):
          string = string.encode(charset, errors)
      if isinstance(safe, text_type):
          safe = safe.encode(charset, errors)
      if isinstance(unsafe, text_type):
          unsafe = unsafe.encode(charset, errors)
      safe = (frozenset(bytearray(safe)) | _always_safe) - frozenset(bytearray(unsafe))
      rv = bytearray()
      for char in bytearray(string):
          if char in safe:
              rv.append(char)
          else:
              rv.extend(_bytetohex[char])
      return to_native(bytes(rv))
  
  
  def url_quote_plus(string, charset='utf-8', errors='strict', safe=''):
      """URL encode a single string with the given encoding and convert
      whitespace to "+".
  
      :param s: The string to quote.
      :param charset: The charset to be used.
      :param safe: An optional sequence of safe characters.
      """
      return url_quote(string, charset, errors, safe + ' ', '+').replace(' ', '+')
  
  
  def url_unparse(components):
      """The reverse operation to :meth:`url_parse`.  This accepts arbitrary
      as well as :class:`URL` tuples and returns a URL as a string.
  
      :param components: the parsed URL as tuple which should be converted
                         into a URL string.
      """
      scheme, netloc, path, query, fragment = \
          normalize_string_tuple(components)
      s = make_literal_wrapper(scheme)
      url = s('')
  
      # We generally treat file:///x and file:/x the same which is also
      # what browsers seem to do.  This also allows us to ignore a schema
      # register for netloc utilization or having to differenciate between
      # empty and missing netloc.
      if netloc or (scheme and path.startswith(s('/'))):
          if path and path[:1] != s('/'):
              path = s('/') + path
          url = s('//') + (netloc or s('')) + path
      elif path:
          url += path
      if scheme:
          url = scheme + s(':') + url
      if query:
          url = url + s('?') + query
      if fragment:
          url = url + s('#') + fragment
      return url
  
  
  def url_unquote(string, charset='utf-8', errors='replace', unsafe=''):
      """URL decode a single string with a given encoding.  If the charset
      is set to `None` no unicode decoding is performed and raw bytes
      are returned.
  
      :param s: the string to unquote.
      :param charset: the charset of the query string.  If set to `None`
                      no unicode decoding will take place.
      :param errors: the error handling for the charset decoding.
      """
      rv = _unquote_to_bytes(string, unsafe)
      if charset is not None:
          rv = rv.decode(charset, errors)
      return rv
  
  
  def url_unquote_plus(s, charset='utf-8', errors='replace'):
      """URL decode a single string with the given `charset` and decode "+" to
      whitespace.
  
      Per default encoding errors are ignored.  If you want a different behavior
      you can set `errors` to ``'replace'`` or ``'strict'``.  In strict mode a
      :exc:`HTTPUnicodeError` is raised.
  
      :param s: The string to unquote.
      :param charset: the charset of the query string.  If set to `None`
                      no unicode decoding will take place.
      :param errors: The error handling for the `charset` decoding.
      """
      if isinstance(s, text_type):
          s = s.replace(u'+', u' ')
      else:
          s = s.replace(b'+', b' ')
      return url_unquote(s, charset, errors)
  
  
  def url_fix(s, charset='utf-8'):
      r"""Sometimes you get an URL by a user that just isn't a real URL because
      it contains unsafe characters like ' ' and so on. This function can fix
      some of the problems in a similar way browsers handle data entered by the
      user:
  
      >>> url_fix(u'http://de.wikipedia.org/wiki/Elf (Begriffskl\xe4rung)')
      'http://de.wikipedia.org/wiki/Elf%20(Begriffskl%C3%A4rung)'
  
      :param s: the string with the URL to fix.
      :param charset: The target charset for the URL if the url was given as
                      unicode string.
      """
      # First step is to switch to unicode processing and to convert
      # backslashes (which are invalid in URLs anyways) to slashes.  This is
      # consistent with what Chrome does.
      s = to_unicode(s, charset, 'replace').replace('\\', '/')
  
      # For the specific case that we look like a malformed windows URL
      # we want to fix this up manually:
      if s.startswith('file://') and s[7:8].isalpha() and s[8:10] in (':/', '|/'):
          s = 'file:///' + s[7:]
  
      url = url_parse(s)
      path = url_quote(url.path, charset, safe='/%+$!*\'(),')
      qs = url_quote_plus(url.query, charset, safe=':&%=+$!*\'(),')
      anchor = url_quote_plus(url.fragment, charset, safe=':&%=+$!*\'(),')
      return to_native(url_unparse((url.scheme, url.encode_netloc(),
                                    path, qs, anchor)))
  
  
  # not-unreserved characters remain quoted when unquoting to IRI
  _to_iri_unsafe = "".join([chr(c) for c in range(128) if c not in _always_safe])
  
  
  def _codec_error_url_quote(e):
      """Used in :func:`uri_to_iri` after unquoting to re-quote any
      invalid bytes.
      """
      out = _fast_url_quote(e.object[e.start:e.end])
  
      if PY2:
          out = out.decode("utf-8")
  
      return out, e.end
  
  
  codecs.register_error("werkzeug.url_quote", _codec_error_url_quote)
  
  
  def uri_to_iri(uri, charset="utf-8", errors="werkzeug.url_quote"):
      """Convert a URI to an IRI. All valid UTF-8 characters are unquoted,
      leaving all reserved and invalid characters quoted. If the URL has
      a domain, it is decoded from Punycode.
  
      >>> uri_to_iri("http://xn--n3h.net/p%C3%A5th?q=%C3%A8ry%DF")
      'http://\u2603.net/p\xe5th?q=\xe8ry%DF'
  
      :param uri: The URI to convert.
      :param charset: The encoding to encode unquoted bytes with.
      :param errors: Error handler to use during ``bytes.encode``. By
          default, invalid bytes are left quoted.
  
      .. versionchanged:: 0.15
          All reserved and invalid characters remain quoted. Previously,
          only some reserved characters were preserved, and invalid bytes
          were replaced instead of left quoted.
  
      .. versionadded:: 0.6
      """
      if isinstance(uri, tuple):
          uri = url_unparse(uri)
  
      uri = url_parse(to_unicode(uri, charset))
      path = url_unquote(uri.path, charset, errors, _to_iri_unsafe)
      query = url_unquote(uri.query, charset, errors, _to_iri_unsafe)
      fragment = url_unquote(uri.fragment, charset, errors, _to_iri_unsafe)
      return url_unparse((uri.scheme, uri.decode_netloc(), path, query, fragment))
  
  
  # reserved characters remain unquoted when quoting to URI
  _to_uri_safe = ":/?#[]@!$&'()*+,;=%"
  
  
  def iri_to_uri(iri, charset="utf-8", errors="strict", safe_conversion=False):
      """Convert an IRI to a URI. All non-ASCII and unsafe characters are
      quoted. If the URL has a domain, it is encoded to Punycode.
  
      >>> iri_to_uri('http://\u2603.net/p\xe5th?q=\xe8ry%DF')
      'http://xn--n3h.net/p%C3%A5th?q=%C3%A8ry%DF'
  
      :param iri: The IRI to convert.
      :param charset: The encoding of the IRI.
      :param errors: Error handler to use during ``bytes.encode``.
      :param safe_conversion: Return the URL unchanged if it only contains
          ASCII characters and no whitespace. See the explanation below.
  
      There is a general problem with IRI conversion with some protocols
      that are in violation of the URI specification. Consider the
      following two IRIs::
  
          magnet:?xt=uri:whatever
          itms-services://?action=download-manifest
  
      After parsing, we don't know if the scheme requires the ``//``,
      which is dropped if empty, but conveys different meanings in the
      final URL if it's present or not. In this case, you can use
      ``safe_conversion``, which will return the URL unchanged if it only
      contains ASCII characters and no whitespace. This can result in a
      URI with unquoted characters if it was not already quoted correctly,
      but preserves the URL's semantics. Werkzeug uses this for the
      ``Location`` header for redirects.
  
      .. versionchanged:: 0.15
          All reserved characters remain unquoted. Previously, only some
          reserved characters were left unquoted.
  
      .. versionchanged:: 0.9.6
         The ``safe_conversion`` parameter was added.
  
      .. versionadded:: 0.6
      """
      if isinstance(iri, tuple):
          iri = url_unparse(iri)
  
      if safe_conversion:
          # If we're not sure if it's safe to convert the URL, and it only
          # contains ASCII characters, return it unconverted.
          try:
              native_iri = to_native(iri)
              ascii_iri = native_iri.encode('ascii')
  
              # Only return if it doesn't have whitespace. (Why?)
              if len(ascii_iri.split()) == 1:
                  return native_iri
          except UnicodeError:
              pass
  
      iri = url_parse(to_unicode(iri, charset, errors))
      path = url_quote(iri.path, charset, errors, _to_uri_safe)
      query = url_quote(iri.query, charset, errors, _to_uri_safe)
      fragment = url_quote(iri.fragment, charset, errors, _to_uri_safe)
      return to_native(
          url_unparse((iri.scheme, iri.encode_netloc(), path, query, fragment))
      )
  
  
  def url_decode(s, charset='utf-8', decode_keys=False, include_empty=True,
                 errors='replace', separator='&', cls=None):
      """
      Parse a querystring and return it as :class:`MultiDict`.  There is a
      difference in key decoding on different Python versions.  On Python 3
      keys will always be fully decoded whereas on Python 2, keys will
      remain bytestrings if they fit into ASCII.  On 2.x keys can be forced
      to be unicode by setting `decode_keys` to `True`.
  
      If the charset is set to `None` no unicode decoding will happen and
      raw bytes will be returned.
  
      Per default a missing value for a key will default to an empty key.  If
      you don't want that behavior you can set `include_empty` to `False`.
  
      Per default encoding errors are ignored.  If you want a different behavior
      you can set `errors` to ``'replace'`` or ``'strict'``.  In strict mode a
      `HTTPUnicodeError` is raised.
  
      .. versionchanged:: 0.5
         In previous versions ";" and "&" could be used for url decoding.
         This changed in 0.5 where only "&" is supported.  If you want to
         use ";" instead a different `separator` can be provided.
  
         The `cls` parameter was added.
  
      :param s: a string with the query string to decode.
      :param charset: the charset of the query string.  If set to `None`
                      no unicode decoding will take place.
      :param decode_keys: Used on Python 2.x to control whether keys should
                          be forced to be unicode objects.  If set to `True`
                          then keys will be unicode in all cases. Otherwise,
                          they remain `str` if they fit into ASCII.
      :param include_empty: Set to `False` if you don't want empty values to
                            appear in the dict.
      :param errors: the decoding error behavior.
      :param separator: the pair separator to be used, defaults to ``&``
      :param cls: an optional dict class to use.  If this is not specified
                         or `None` the default :class:`MultiDict` is used.
      """
      if cls is None:
          cls = MultiDict
      if isinstance(s, text_type) and not isinstance(separator, text_type):
          separator = separator.decode(charset or 'ascii')
      elif isinstance(s, bytes) and not isinstance(separator, bytes):
          separator = separator.encode(charset or 'ascii')
      return cls(_url_decode_impl(s.split(separator), charset, decode_keys,
                                  include_empty, errors))
  
  
  def url_decode_stream(stream, charset='utf-8', decode_keys=False,
                        include_empty=True, errors='replace', separator='&',
                        cls=None, limit=None, return_iterator=False):
      """Works like :func:`url_decode` but decodes a stream.  The behavior
      of stream and limit follows functions like
      :func:`~werkzeug.wsgi.make_line_iter`.  The generator of pairs is
      directly fed to the `cls` so you can consume the data while it's
      parsed.
  
      .. versionadded:: 0.8
  
      :param stream: a stream with the encoded querystring
      :param charset: the charset of the query string.  If set to `None`
                      no unicode decoding will take place.
      :param decode_keys: Used on Python 2.x to control whether keys should
                          be forced to be unicode objects.  If set to `True`,
                          keys will be unicode in all cases. Otherwise, they
                          remain `str` if they fit into ASCII.
      :param include_empty: Set to `False` if you don't want empty values to
                            appear in the dict.
      :param errors: the decoding error behavior.
      :param separator: the pair separator to be used, defaults to ``&``
      :param cls: an optional dict class to use.  If this is not specified
                         or `None` the default :class:`MultiDict` is used.
      :param limit: the content length of the URL data.  Not necessary if
                    a limited stream is provided.
      :param return_iterator: if set to `True` the `cls` argument is ignored
                              and an iterator over all decoded pairs is
                              returned
      """
      from werkzeug.wsgi import make_chunk_iter
      if return_iterator:
          cls = lambda x: x
      elif cls is None:
          cls = MultiDict
      pair_iter = make_chunk_iter(stream, separator, limit)
      return cls(_url_decode_impl(pair_iter, charset, decode_keys,
                                  include_empty, errors))
  
  
  def _url_decode_impl(pair_iter, charset, decode_keys, include_empty, errors):
      for pair in pair_iter:
          if not pair:
              continue
          s = make_literal_wrapper(pair)
          equal = s('=')
          if equal in pair:
              key, value = pair.split(equal, 1)
          else:
              if not include_empty:
                  continue
              key = pair
              value = s('')
          key = url_unquote_plus(key, charset, errors)
          if charset is not None and PY2 and not decode_keys:
              key = try_coerce_native(key)
          yield key, url_unquote_plus(value, charset, errors)
  
  
  def url_encode(obj, charset='utf-8', encode_keys=False, sort=False, key=None,
                 separator=b'&'):
      """URL encode a dict/`MultiDict`.  If a value is `None` it will not appear
      in the result string.  Per default only values are encoded into the target
      charset strings.  If `encode_keys` is set to ``True`` unicode keys are
      supported too.
  
      If `sort` is set to `True` the items are sorted by `key` or the default
      sorting algorithm.
  
      .. versionadded:: 0.5
          `sort`, `key`, and `separator` were added.
  
      :param obj: the object to encode into a query string.
      :param charset: the charset of the query string.
      :param encode_keys: set to `True` if you have unicode keys. (Ignored on
                          Python 3.x)
      :param sort: set to `True` if you want parameters to be sorted by `key`.
      :param separator: the separator to be used for the pairs.
      :param key: an optional function to be used for sorting.  For more details
                  check out the :func:`sorted` documentation.
      """
      separator = to_native(separator, 'ascii')
      return separator.join(_url_encode_impl(obj, charset, encode_keys, sort, key))
  
  
  def url_encode_stream(obj, stream=None, charset='utf-8', encode_keys=False,
                        sort=False, key=None, separator=b'&'):
      """Like :meth:`url_encode` but writes the results to a stream
      object.  If the stream is `None` a generator over all encoded
      pairs is returned.
  
      .. versionadded:: 0.8
  
      :param obj: the object to encode into a query string.
      :param stream: a stream to write the encoded object into or `None` if
                     an iterator over the encoded pairs should be returned.  In
                     that case the separator argument is ignored.
      :param charset: the charset of the query string.
      :param encode_keys: set to `True` if you have unicode keys. (Ignored on
                          Python 3.x)
      :param sort: set to `True` if you want parameters to be sorted by `key`.
      :param separator: the separator to be used for the pairs.
      :param key: an optional function to be used for sorting.  For more details
                  check out the :func:`sorted` documentation.
      """
      separator = to_native(separator, 'ascii')
      gen = _url_encode_impl(obj, charset, encode_keys, sort, key)
      if stream is None:
          return gen
      for idx, chunk in enumerate(gen):
          if idx:
              stream.write(separator)
          stream.write(chunk)
  
  
  def url_join(base, url, allow_fragments=True):
      """Join a base URL and a possibly relative URL to form an absolute
      interpretation of the latter.
  
      :param base: the base URL for the join operation.
      :param url: the URL to join.
      :param allow_fragments: indicates whether fragments should be allowed.
      """
      if isinstance(base, tuple):
          base = url_unparse(base)
      if isinstance(url, tuple):
          url = url_unparse(url)
  
      base, url = normalize_string_tuple((base, url))
      s = make_literal_wrapper(base)
  
      if not base:
          return url
      if not url:
          return base
  
      bscheme, bnetloc, bpath, bquery, bfragment = \
          url_parse(base, allow_fragments=allow_fragments)
      scheme, netloc, path, query, fragment = \
          url_parse(url, bscheme, allow_fragments)
      if scheme != bscheme:
          return url
      if netloc:
          return url_unparse((scheme, netloc, path, query, fragment))
      netloc = bnetloc
  
      if path[:1] == s('/'):
          segments = path.split(s('/'))
      elif not path:
          segments = bpath.split(s('/'))
          if not query:
              query = bquery
      else:
          segments = bpath.split(s('/'))[:-1] + path.split(s('/'))
  
      # If the rightmost part is "./" we want to keep the slash but
      # remove the dot.
      if segments[-1] == s('.'):
          segments[-1] = s('')
  
      # Resolve ".." and "."
      segments = [segment for segment in segments if segment != s('.')]
      while 1:
          i = 1
          n = len(segments) - 1
          while i < n:
              if segments[i] == s('..') and \
                 segments[i - 1] not in (s(''), s('..')):
                  del segments[i - 1:i + 1]
                  break
              i += 1
          else:
              break
  
      # Remove trailing ".." if the URL is absolute
      unwanted_marker = [s(''), s('..')]
      while segments[:2] == unwanted_marker:
          del segments[1]
  
      path = s('/').join(segments)
      return url_unparse((scheme, netloc, path, query, fragment))
  
  
  class Href(object):
  
      """Implements a callable that constructs URLs with the given base. The
      function can be called with any number of positional and keyword
      arguments which than are used to assemble the URL.  Works with URLs
      and posix paths.
  
      Positional arguments are appended as individual segments to
      the path of the URL:
  
      >>> href = Href('/foo')
      >>> href('bar', 23)
      '/foo/bar/23'
      >>> href('foo', bar=23)
      '/foo/foo?bar=23'
  
      If any of the arguments (positional or keyword) evaluates to `None` it
      will be skipped.  If no keyword arguments are given the last argument
      can be a :class:`dict` or :class:`MultiDict` (or any other dict subclass),
      otherwise the keyword arguments are used for the query parameters, cutting
      off the first trailing underscore of the parameter name:
  
      >>> href(is_=42)
      '/foo?is=42'
      >>> href({'foo': 'bar'})
      '/foo?foo=bar'
  
      Combining of both methods is not allowed:
  
      >>> href({'foo': 'bar'}, bar=42)
      Traceback (most recent call last):
        ...
      TypeError: keyword arguments and query-dicts can't be combined
  
      Accessing attributes on the href object creates a new href object with
      the attribute name as prefix:
  
      >>> bar_href = href.bar
      >>> bar_href("blub")
      '/foo/bar/blub'
  
      If `sort` is set to `True` the items are sorted by `key` or the default
      sorting algorithm:
  
      >>> href = Href("/", sort=True)
      >>> href(a=1, b=2, c=3)
      '/?a=1&b=2&c=3'
  
      .. versionadded:: 0.5
          `sort` and `key` were added.
      """
  
      def __init__(self, base='./', charset='utf-8', sort=False, key=None):
          if not base:
              base = './'
          self.base = base
          self.charset = charset
          self.sort = sort
          self.key = key
  
      def __getattr__(self, name):
          if name[:2] == '__':
              raise AttributeError(name)
          base = self.base
          if base[-1:] != '/':
              base += '/'
          return Href(url_join(base, name), self.charset, self.sort, self.key)
  
      def __call__(self, *path, **query):
          if path and isinstance(path[-1], dict):
              if query:
                  raise TypeError('keyword arguments and query-dicts '
                                  'can\'t be combined')
              query, path = path[-1], path[:-1]
          elif query:
              query = dict([(k.endswith('_') and k[:-1] or k, v)
                            for k, v in query.items()])
          path = '/'.join([to_unicode(url_quote(x, self.charset), 'ascii')
                           for x in path if x is not None]).lstrip('/')
          rv = self.base
          if path:
              if not rv.endswith('/'):
                  rv += '/'
              rv = url_join(rv, './' + path)
          if query:
              rv += '?' + to_unicode(url_encode(query, self.charset, sort=self.sort,
                                                key=self.key), 'ascii')
          return to_native(rv)
  