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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  import copy 
 55  try: 
 56      from urlparse import urljoin 
 57      from urllib2 import urlopen 
 58  except ImportError: 
 59      # Python 3 
 60      from urllib.parse import urljoin 
 61      from urllib.request import urlopen 
 62   
 63  try: 
 64      set 
 65  except NameError: 
 66      # Python 2.3 
 67      from sets import Set as set 
 68   
 69  XINCLUDE = "{http://www.w3.org/2001/XInclude}" 
 70   
 71  XINCLUDE_INCLUDE = XINCLUDE + "include" 
 72  XINCLUDE_FALLBACK = XINCLUDE + "fallback" 
 73   
 74  ## 
 75  # Fatal include error. 
 76   
 79   
 80  ## 
 81  # ET compatible default loader. 
 82  # This loader reads an included resource from disk. 
 83  # 
 84  # @param href Resource reference. 
 85  # @param parse Parse mode.  Either "xml" or "text". 
 86  # @param encoding Optional text encoding. 
 87  # @return The expanded resource.  If the parse mode is "xml", this 
 88  #    is an ElementTree instance.  If the parse mode is "text", this 
 89  #    is a Unicode string.  If the loader fails, it can return None 
 90  #    or raise an IOError exception. 
 91  # @throws IOError If the loader fails to load the resource. 
 92   
 94      file = open(href, 'rb') 
 95      if parse == "xml": 
 96          data = etree.parse(file).getroot() 
 97      else: 
 98          data = file.read() 
 99          if not encoding: 
100              encoding = 'utf-8' 
101          data = data.decode(encoding) 
102      file.close() 
103      return data 
104   
105  ## 
106  # Default loader used by lxml.etree - handles custom resolvers properly 
107  #  
108   
110      if parse == "xml": 
111          data = etree.parse(href, parser).getroot() 
112      else: 
113          if "://" in href: 
114              f = urlopen(href) 
115          else: 
116              f = open(href, 'rb') 
117          data = f.read() 
118          f.close() 
119          if not encoding: 
120              encoding = 'utf-8' 
121          data = data.decode(encoding) 
122      return data 
123   
124  ## 
125  # Wrapper for ET compatibility - drops the parser 
126   
130      return load 
131   
132   
133  ## 
134  # Expand XInclude directives. 
135  # 
136  # @param elem Root element. 
137  # @param loader Optional resource loader.  If omitted, it defaults 
138  #     to {@link default_loader}.  If given, it should be a callable 
139  #     that implements the same interface as <b>default_loader</b>. 
140  # @throws FatalIncludeError If the function fails to include a given 
141  #     resource, or if the tree contains malformed XInclude elements. 
142  # @throws IOError If the function fails to load a given resource. 
143  # @returns the node or its replacement if it was an XInclude node 
144   
146      if base_url is None: 
147          if hasattr(elem, 'getroot'): 
148              tree = elem 
149              elem = elem.getroot() 
150          else: 
151              tree = elem.getroottree() 
152          if hasattr(tree, 'docinfo'): 
153              base_url = tree.docinfo.URL 
154      elif hasattr(elem, 'getroot'): 
155          elem = elem.getroot() 
156      _include(elem, loader, base_url=base_url) 
157   
159      if loader is not None: 
160          load_include = _wrap_et_loader(loader) 
161      else: 
162          load_include = _lxml_default_loader 
163   
164      if _parent_hrefs is None: 
165          _parent_hrefs = set() 
166   
167      parser = elem.getroottree().parser 
168   
169      include_elements = list( 
170          elem.iter('{http://www.w3.org/2001/XInclude}*')) 
171   
172      for e in include_elements: 
173          if e.tag == XINCLUDE_INCLUDE: 
174              # process xinclude directive 
175              href = urljoin(base_url, e.get("href")) 
176              parse = e.get("parse", "xml") 
177              parent = e.getparent() 
178              if parse == "xml": 
179                  if href in _parent_hrefs: 
180                      raise FatalIncludeError( 
181                          "recursive include of %r detected" % href 
182                          ) 
183                  _parent_hrefs.add(href) 
184                  node = load_include(href, parse, parser=parser) 
185                  if node is None: 
186                      raise FatalIncludeError( 
187                          "cannot load %r as %r" % (href, parse) 
188                          ) 
189                  node = _include(node, loader, _parent_hrefs) 
190                  if e.tail: 
191                      node.tail = (node.tail or "") + e.tail 
192                  if parent is None: 
193                      return node # replaced the root node! 
194                  parent.replace(e, node) 
195              elif parse == "text": 
196                  text = load_include(href, parse, encoding=e.get("encoding")) 
197                  if text is None: 
198                      raise FatalIncludeError( 
199                          "cannot load %r as %r" % (href, parse) 
200                          ) 
201                  predecessor = e.getprevious() 
202                  if predecessor is not None: 
203                      predecessor.tail = (predecessor.tail or "") + text 
204                  elif parent is None: 
205                      return text # replaced the root node! 
206                  else: 
207                      parent.text = (parent.text or "") + text + (e.tail or "") 
208                  parent.remove(e) 
209              else: 
210                  raise FatalIncludeError( 
211                      "unknown parse type in xi:include tag (%r)" % parse 
212                  ) 
213          elif e.tag == XINCLUDE_FALLBACK: 
214              parent = e.getparent() 
215              if parent is not None and parent.tag != XINCLUDE_INCLUDE: 
216                  raise FatalIncludeError( 
217                      "xi:fallback tag must be child of xi:include (%r)" % e.tag 
218                      ) 
219          else: 
220              raise FatalIncludeError( 
221                  "Invalid element found in XInclude namespace (%r)" % e.tag 
222                  ) 
223      return elem 
224   
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