libs/elementtree/ElementInclude.py

   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
  49 import ElementTree
  50
  51 XINCLUDE = "{http://www.w3.org/2001/XInclude}"
  52
  53 XINCLUDE_INCLUDE = XINCLUDE + "include"
  54 XINCLUDE_FALLBACK = XINCLUDE + "fallback"
  55
  56 ##
  57 # Fatal include error.
  58
  59 class FatalIncludeError(SyntaxError):
  60     pass
  61
  62 ##
  63 # Default loader.  This loader reads an included resource from disk.
  64 #
  65 # @param href Resource reference.
  66 # @param parse Parse mode.  Either "xml" or "text".
  67 # @param encoding Optional text encoding.
  68 # @return The expanded resource.  If the parse mode is "xml", this
  69 #    is an ElementTree instance.  If the parse mode is "text", this
  70 #    is a Unicode string.  If the loader fails, it can return None
  71 #    or raise an IOError exception.
  72 # @throws IOError If the loader fails to load the resource.
  73
  74 def default_loader(href, parse, encoding=None):
  75     file = open(href)
  76     if parse == "xml":
  77         data = ElementTree.parse(file).getroot()
  78     else:
  79         data = file.read()
  80         if encoding:
  81             data = data.decode(encoding)
  82     file.close()
  83     return data
  84
  85 ##
  86 # Expand XInclude directives.
  87 #
  88 # @param elem Root element.
  89 # @param loader Optional resource loader.  If omitted, it defaults
  90 #     to {@link default_loader}.  If given, it should be a callable
  91 #     that implements the same interface as <b>default_loader</b>.
  92 # @throws FatalIncludeError If the function fails to include a given
  93 #     resource, or if the tree contains malformed XInclude elements.
  94 # @throws IOError If the function fails to load a given resource.
  95
  96 def include(elem, loader=None):
  97     if loader is None:
  98         loader = default_loader
  99     # look for xinclude elements
 100     i = 0
 101     while i < len(elem):
 102         e = elem[i]
 103         if e.tag == XINCLUDE_INCLUDE:
 104             # process xinclude directive
 105             href = e.get("href")
 106             parse = e.get("parse", "xml")
 107             if parse == "xml":
 108                 node = loader(href, parse)
 109                 if node is None:
 110                     raise FatalIncludeError(
 111                         "cannot load %r as %r" % (href, parse)
 112                         )
 113                 node = copy.copy(node)
 114                 if e.tail:
 115                     node.tail = (node.tail or "") + e.tail
 116                 elem[i] = node
 117             elif parse == "text":
 118                 text = loader(href, parse, e.get("encoding"))
 119                 if text is None:
 120                     raise FatalIncludeError(
 121                         "cannot load %r as %r" % (href, parse)
 122                         )
 123                 if i:
 124                     node = elem[i-1]
 125                     node.tail = (node.tail or "") + text
 126                 else:
 127                     elem.text = (elem.text or "") + text + (e.tail or "")
 128                 del elem[i]
 129                 continue
 130             else:
 131                 raise FatalIncludeError(
 132                     "unknown parse type in xi:include tag (%r)" % parse
 133                 )
 134         elif e.tag == XINCLUDE_FALLBACK:
 135             raise FatalIncludeError(
 136                 "xi:fallback tag must be child of xi:include (%r)" % e.tag
 137                 )
 138         else:
 139             include(e, loader)
 140         i = i + 1
 141