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  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  from lxml import etree 
 54  try: 
 55      from urlparse import urljoin 
 56      from urllib2 import urlopen 
 57  except ImportError: 
 58      # Python 3 
 59      from urllib.parse import urljoin 
 60      from urllib.request import urlopen 
 61   
 62  XINCLUDE = "{http://www.w3.org/2001/XInclude}" 
 63   
 64  XINCLUDE_INCLUDE = XINCLUDE + "include" 
 65  XINCLUDE_FALLBACK = XINCLUDE + "fallback" 
 66  XINCLUDE_ITER_TAG = XINCLUDE + "*" 
 67   
 68  ## 
 69  # Fatal include error. 
 70   
 73   
 74  ## 
 75  # ET compatible default loader. 
 76  # This loader reads an included resource from disk. 
 77  # 
 78  # @param href Resource reference. 
 79  # @param parse Parse mode.  Either "xml" or "text". 
 80  # @param encoding Optional text encoding. 
 81  # @return The expanded resource.  If the parse mode is "xml", this 
 82  #    is an ElementTree instance.  If the parse mode is "text", this 
 83  #    is a Unicode string.  If the loader fails, it can return None 
 84  #    or raise an IOError exception. 
 85  # @throws IOError If the loader fails to load the resource. 
 86   
 88      file = open(href, 'rb') 
 89      if parse == "xml": 
 90          data = etree.parse(file).getroot() 
 91      else: 
 92          data = file.read() 
 93          if not encoding: 
 94              encoding = 'utf-8' 
 95          data = data.decode(encoding) 
 96      file.close() 
 97      return data 
 98   
 99  ## 
100  # Default loader used by lxml.etree - handles custom resolvers properly 
101  #  
102   
104      if parse == "xml": 
105          data = etree.parse(href, parser).getroot() 
106      else: 
107          if "://" in href: 
108              f = urlopen(href) 
109          else: 
110              f = open(href, 'rb') 
111          data = f.read() 
112          f.close() 
113          if not encoding: 
114              encoding = 'utf-8' 
115          data = data.decode(encoding) 
116      return data 
117   
118  ## 
119  # Wrapper for ET compatibility - drops the parser 
120   
124      return load 
125   
126   
127  ## 
128  # Expand XInclude directives. 
129  # 
130  # @param elem Root element. 
131  # @param loader Optional resource loader.  If omitted, it defaults 
132  #     to {@link default_loader}.  If given, it should be a callable 
133  #     that implements the same interface as <b>default_loader</b>. 
134  # @throws FatalIncludeError If the function fails to include a given 
135  #     resource, or if the tree contains malformed XInclude elements. 
136  # @throws IOError If the function fails to load a given resource. 
137  # @returns the node or its replacement if it was an XInclude node 
138   
140      if base_url is None: 
141          if hasattr(elem, 'getroot'): 
142              tree = elem 
143              elem = elem.getroot() 
144          else: 
145              tree = elem.getroottree() 
146          if hasattr(tree, 'docinfo'): 
147              base_url = tree.docinfo.URL 
148      elif hasattr(elem, 'getroot'): 
149          elem = elem.getroot() 
150      _include(elem, loader, base_url=base_url) 
151   
153      if loader is not None: 
154          load_include = _wrap_et_loader(loader) 
155      else: 
156          load_include = _lxml_default_loader 
157   
158      if _parent_hrefs is None: 
159          _parent_hrefs = set() 
160   
161      parser = elem.getroottree().parser 
162   
163      include_elements = list( 
164          elem.iter(XINCLUDE_ITER_TAG)) 
165   
166      for e in include_elements: 
167          if e.tag == XINCLUDE_INCLUDE: 
168              # process xinclude directive 
169              href = urljoin(base_url, e.get("href")) 
170              parse = e.get("parse", "xml") 
171              parent = e.getparent() 
172              if parse == "xml": 
173                  if href in _parent_hrefs: 
174                      raise FatalIncludeError( 
175                          "recursive include of %r detected" % href 
176                          ) 
177                  _parent_hrefs.add(href) 
178                  node = load_include(href, parse, parser=parser) 
179                  if node is None: 
180                      raise FatalIncludeError( 
181                          "cannot load %r as %r" % (href, parse) 
182                          ) 
183                  node = _include(node, loader, _parent_hrefs) 
184                  if e.tail: 
185                      node.tail = (node.tail or "") + e.tail 
186                  if parent is None: 
187                      return node # replaced the root node! 
188                  parent.replace(e, node) 
189              elif parse == "text": 
190                  text = load_include(href, parse, encoding=e.get("encoding")) 
191                  if text is None: 
192                      raise FatalIncludeError( 
193                          "cannot load %r as %r" % (href, parse) 
194                          ) 
195                  predecessor = e.getprevious() 
196                  if predecessor is not None: 
197                      predecessor.tail = (predecessor.tail or "") + text 
198                  elif parent is None: 
199                      return text # replaced the root node! 
200                  else: 
201                      parent.text = (parent.text or "") + text + (e.tail or "") 
202                  parent.remove(e) 
203              else: 
204                  raise FatalIncludeError( 
205                      "unknown parse type in xi:include tag (%r)" % parse 
206                  ) 
207          elif e.tag == XINCLUDE_FALLBACK: 
208              parent = e.getparent() 
209              if parent is not None and parent.tag != XINCLUDE_INCLUDE: 
210                  raise FatalIncludeError( 
211                      "xi:fallback tag must be child of xi:include (%r)" % e.tag 
212                      ) 
213          else: 
214              raise FatalIncludeError( 
215                  "Invalid element found in XInclude namespace (%r)" % e.tag 
216                  ) 
217      return elem 
218   
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