lxml.ElementInclude

Package lxml :: Module ElementInclude |
[frames] | no frames]

# 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  While lxml.etree has full support for XInclude (see
     48  `etree.ElementTree.xinclude()`), this module provides a simpler, pure
     49  Python, ElementTree compatible implementation that supports a simple
     50  form of custom URL resolvers.
     51  """
     52
     53  import copy, etree
     54  from urlparse import urljoin
     55  from urllib2 import urlopen
     56
     57  try:
     58      set
     59  except NameError:
     60      from sets import Set as set
     61
     62  XINCLUDE = "{http://www.w3.org/2001/XInclude}"
     63
     64  XINCLUDE_INCLUDE = XINCLUDE + "include"
     65  XINCLUDE_FALLBACK = XINCLUDE + "fallback"
     66
     67  ##
     68  # Fatal include error.
     69
     70 -class FatalIncludeError(etree.LxmlSyntaxError):
     71      pass
     72
     73  ##
     74  # ET compatible default loader.
     75  # This loader reads an included resource from disk.
     76  #
     77  # @param href Resource reference.
     78  # @param parse Parse mode.  Either "xml" or "text".
     79  # @param encoding Optional text encoding.
     80  # @return The expanded resource.  If the parse mode is "xml", this
     81  #    is an ElementTree instance.  If the parse mode is "text", this
     82  #    is a Unicode string.  If the loader fails, it can return None
     83  #    or raise an IOError exception.
     84  # @throws IOError If the loader fails to load the resource.
     85
     86 -def default_loader(href, parse, encoding=None):
     87      file = open(href)
     88      if parse == "xml":
     89          data = etree.parse(file).getroot()
     90      else:
     91          data = file.read()
     92          if encoding:
     93              data = data.decode(encoding)
     94      file.close()
     95      return data
     96
     97  ##
     98  # Default loader used by lxml.etree - handles custom resolvers properly
     99  #
    100
    101 -def _lxml_default_loader(href, parse, encoding=None, parser=None):
    102      if parse == "xml":
    103          data = etree.parse(href, parser).getroot()
    104      else:
    105          if "://" in href:
    106              f = urlopen(href)
    107          else:
    108              f = open(href)
    109          data = f.read()
    110          f.close()
    111          if encoding:
    112              data = data.decode(encoding)
    113      return data
    114
    115  ##
    116  # Wrapper for ET compatibility - drops the parser
    117
    118 -def _wrap_et_loader(loader):
    119      def load(href, parse, encoding=None, parser=None):
    120          return loader(href, parse, encoding)
    121      return load
    122
    123
    124  ##
    125  # Expand XInclude directives.
    126  #
    127  # @param elem Root element.
    128  # @param loader Optional resource loader.  If omitted, it defaults
    129  #     to {@link default_loader}.  If given, it should be a callable
    130  #     that implements the same interface as <b>default_loader</b>.
    131  # @throws FatalIncludeError If the function fails to include a given
    132  #     resource, or if the tree contains malformed XInclude elements.
    133  # @throws IOError If the function fails to load a given resource.
    134  # @returns the node or its replacement if it was an XInclude node
    135
    136 -def include(elem, loader=None, base_url=None):
    137      if base_url is None:
    138          if hasattr(elem, 'getroot'):
    139              tree = elem
    140              elem = elem.getroot()
    141          else:
    142              tree = elem.getroottree()
    143          if hasattr(tree, 'docinfo'):
    144              base_url = tree.docinfo.URL
    145      elif hasattr(elem, 'getroot'):
    146          elem = elem.getroot()
    147      _include(elem, loader, base_url=base_url)
    148
    149 -def _include(elem, loader=None, _parent_hrefs=None, base_url=None):
    150      if loader is not None:
    151          load_include = _wrap_et_loader(loader)
    152      else:
    153          load_include = _lxml_default_loader
    154
    155      if _parent_hrefs is None:
    156          _parent_hrefs = set()
    157
    158      parser = elem.getroottree().parser
    159
    160      include_elements = list(
    161          elem.getiterator('{http://www.w3.org/2001/XInclude}*'))
    162
    163      for e in include_elements:
    164          if e.tag == XINCLUDE_INCLUDE:
    165              # process xinclude directive
    166              href = urljoin(base_url, e.get("href"))
    167              parse = e.get("parse", "xml")
    168              parent = e.getparent()
    169              if parse == "xml":
    170                  if href in _parent_hrefs:
    171                      raise FatalIncludeError(
    172                          "recursive include of %r detected" % href
    173                          )
    174                  _parent_hrefs.add(href)
    175                  node = load_include(href, parse, parser=parser)
    176                  if node is None:
    177                      raise FatalIncludeError(
    178                          "cannot load %r as %r" % (href, parse)
    179                          )
    180                  node = _include(node, loader, _parent_hrefs)
    181                  if e.tail:
    182                      node.tail = (node.tail or "") + e.tail
    183                  if parent is None:
    184                      return node # replaced the root node!
    185                  parent.replace(e, node)
    186              elif parse == "text":
    187                  text = load_include(href, parse, encoding=e.get("encoding"))
    188                  if text is None:
    189                      raise FatalIncludeError(
    190                          "cannot load %r as %r" % (href, parse)
    191                          )
    192                  predecessor = e.getprevious()
    193                  if predecessor is not None:
    194                      predecessor.tail = (predecessor.tail or "") + text
    195                  elif parent is None:
    196                      return text # replaced the root node!
    197                  else:
    198                      parent.text = (parent.text or "") + text + (e.tail or "")
    199                  parent.remove(e)
    200              else:
    201                  raise FatalIncludeError(
    202                      "unknown parse type in xi:include tag (%r)" % parse
    203                  )
    204          elif e.tag == XINCLUDE_FALLBACK:
    205              parent = e.getparent()
    206              if parent is not None and parent.tag != XINCLUDE_INCLUDE:
    207                  raise FatalIncludeError(
    208                      "xi:fallback tag must be child of xi:include (%r)" % e.tag
    209                      )
    210          else:
    211              raise FatalIncludeError(
    212                  "Invalid element found in XInclude namespace (%r)" % e.tag
    213                  )
    214      return elem
    215