Package lxml :: Module ElementInclude

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# Source Code for Module lxml.ElementInclude

      1  #
      2  # ElementTree
      3  # $Id: ElementInclude.py 1862 2004-06-18 07:31:02Z Fredrik $
      4  #
      5  # limited xinclude support for element trees
      6  #
      7  # history:
      8  # 2003-08-15 fl   created
      9  # 2003-11-14 fl   fixed default loader
     10  #
     11  # Copyright (c) 2003-2004 by Fredrik Lundh.  All rights reserved.
     12  #
     13  # fredrik@pythonware.com
     14  # http://www.pythonware.com
     15  #
     16  # --------------------------------------------------------------------
     17  # The ElementTree toolkit is
     18  #
     19  # Copyright (c) 1999-2004 by Fredrik Lundh
     20  #
     21  # By obtaining, using, and/or copying this software and/or its
     22  # associated documentation, you agree that you have read, understood,
     23  # and will comply with the following terms and conditions:
     24  #
     25  # Permission to use, copy, modify, and distribute this software and
     26  # its associated documentation for any purpose and without fee is
     27  # hereby granted, provided that the above copyright notice appears in
     28  # all copies, and that both that copyright notice and this permission
     29  # notice appear in supporting documentation, and that the name of
     30  # Secret Labs AB or the author not be used in advertising or publicity
     31  # pertaining to distribution of the software without specific, written
     32  # prior permission.
     33  #
     34  # SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
     35  # TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
     36  # ABILITY AND FITNESS.  IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
     37  # BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
     38  # DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
     39  # WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
     40  # ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
     41  # OF THIS SOFTWARE.
     42  # --------------------------------------------------------------------
     43
     44  ##
     45  # Limited XInclude support for the ElementTree package.
     46  ##
     47
     48  import copy, etree
     49  from urlparse import urljoin
     50  from urllib2 import urlopen
     51
     52  try:
     53      set
     54  except NameError:
     55      from sets import Set as set
     56
     57  XINCLUDE = "{http://www.w3.org/2001/XInclude}"
     58
     59  XINCLUDE_INCLUDE = XINCLUDE + "include"
     60  XINCLUDE_FALLBACK = XINCLUDE + "fallback"
     61
     62  ##
     63  # Fatal include error.
     64
     65 -class FatalIncludeError(etree.LxmlSyntaxError):
     66      pass
     67
     68  ##
     69  # ET compatible default loader.
     70  # This loader reads an included resource from disk.
     71  #
     72  # @param href Resource reference.
     73  # @param parse Parse mode.  Either "xml" or "text".
     74  # @param encoding Optional text encoding.
     75  # @return The expanded resource.  If the parse mode is "xml", this
     76  #    is an ElementTree instance.  If the parse mode is "text", this
     77  #    is a Unicode string.  If the loader fails, it can return None
     78  #    or raise an IOError exception.
     79  # @throws IOError If the loader fails to load the resource.
     80
     81 -def default_loader(href, parse, encoding=None):
     82      file = open(href)
     83      if parse == "xml":
     84          data = etree.parse(file).getroot()
     85      else:
     86          data = file.read()
     87          if encoding:
     88              data = data.decode(encoding)
     89      file.close()
     90      return data
     91
     92  ##
     93  # Default loader used by lxml.etree - handles custom resolvers properly
     94  #
     95
     96 -def _lxml_default_loader(href, parse, encoding=None, parser=None):
     97      if parse == "xml":
     98          data = etree.parse(href, parser).getroot()
     99      else:
    100          if "://" in href:
    101              f = urlopen(href)
    102          else:
    103              f = open(href)
    104          data = f.read()
    105          f.close()
    106          if encoding:
    107              data = data.decode(encoding)
    108      return data
    109
    110  ##
    111  # Wrapper for ET compatibility - drops the parser
    112
    113 -def _wrap_et_loader(loader):
    114      def load(href, parse, encoding=None, parser=None):
    115          return loader(href, parse, encoding)
    116      return load
    117
    118
    119  ##
    120  # Expand XInclude directives.
    121  #
    122  # @param elem Root element.
    123  # @param loader Optional resource loader.  If omitted, it defaults
    124  #     to {@link default_loader}.  If given, it should be a callable
    125  #     that implements the same interface as <b>default_loader</b>.
    126  # @throws FatalIncludeError If the function fails to include a given
    127  #     resource, or if the tree contains malformed XInclude elements.
    128  # @throws IOError If the function fails to load a given resource.
    129  # @returns the node or its replacement if it was an XInclude node
    130
    131 -def include(elem, loader=None, base_url=None):
    132      if base_url is None:
    133          if hasattr(elem, 'getroot'):
    134              tree = elem
    135              elem = elem.getroot()
    136          else:
    137              tree = elem.getroottree()
    138          if hasattr(tree, 'docinfo'):
    139              base_url = tree.docinfo.URL
    140      elif hasattr(elem, 'getroot'):
    141          elem = elem.getroot()
    142      _include(elem, loader, base_url=base_url)
    143
    144 -def _include(elem, loader=None, _parent_hrefs=None, base_url=None):
    145      if loader is not None:
    146          load_include = _wrap_et_loader(loader)
    147      else:
    148          load_include = _lxml_default_loader
    149
    150      if _parent_hrefs is None:
    151          _parent_hrefs = set()
    152
    153      parser = elem.getroottree().parser
    154
    155      include_elements = list(
    156          elem.getiterator('{http://www.w3.org/2001/XInclude}*'))
    157
    158      for e in include_elements:
    159          if e.tag == XINCLUDE_INCLUDE:
    160              # process xinclude directive
    161              href = urljoin(base_url, e.get("href"))
    162              parse = e.get("parse", "xml")
    163              parent = e.getparent()
    164              if parse == "xml":
    165                  if href in _parent_hrefs:
    166                      raise FatalIncludeError(
    167                          "recursive include of %r detected" % href
    168                          )
    169                  _parent_hrefs.add(href)
    170                  node = load_include(href, parse, parser=parser)
    171                  if node is None:
    172                      raise FatalIncludeError(
    173                          "cannot load %r as %r" % (href, parse)
    174                          )
    175                  node = _include(node, loader, _parent_hrefs)
    176                  if e.tail:
    177                      node.tail = (node.tail or "") + e.tail
    178                  if parent is None:
    179                      return node # replaced the root node!
    180                  parent.replace(e, node)
    181              elif parse == "text":
    182                  text = load_include(href, parse, encoding=e.get("encoding"))
    183                  if text is None:
    184                      raise FatalIncludeError(
    185                          "cannot load %r as %r" % (href, parse)
    186                          )
    187                  predecessor = e.getprevious()
    188                  if predecessor is not None:
    189                      predecessor.tail = (predecessor.tail or "") + text
    190                  elif parent is None:
    191                      return text # replaced the root node!
    192                  else:
    193                      parent.text = (parent.text or "") + text + (e.tail or "")
    194                  parent.remove(e)
    195              else:
    196                  raise FatalIncludeError(
    197                      "unknown parse type in xi:include tag (%r)" % parse
    198                  )
    199          elif e.tag == XINCLUDE_FALLBACK:
    200              parent = e.getparent()
    201              if parent is not None and parent.tag != XINCLUDE_INCLUDE:
    202                  raise FatalIncludeError(
    203                      "xi:fallback tag must be child of xi:include (%r)" % e.tag
    204                      )
    205          else:
    206              raise FatalIncludeError(
    207                  "Invalid element found in XInclude namespace (%r)" % e.tag
    208                  )
    209      return elem
    210