lxml.ElementInclude

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 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

77 -class FatalIncludeError(etree.LxmlSyntaxError):

78 pass

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

93 -def default_loader(href, parse, encoding=None):

94 file = open(href) 95 if parse == "xml": 96 data = etree.parse(file).getroot() 97 else: 98 data = file.read() 99 if encoding: 100 data = data.decode(encoding) 101 file.close() 102 return data

103 104 ## 105 # Default loader used by lxml.etree - handles custom resolvers properly 106 # 107

108 -def _lxml_default_loader(href, parse, encoding=None, parser=None):

109 if parse == "xml": 110 data = etree.parse(href, parser).getroot() 111 else: 112 if "://" in href: 113 f = urlopen(href) 114 else: 115 f = open(href) 116 data = f.read() 117 f.close() 118 if encoding: 119 data = data.decode(encoding) 120 return data

121 122 ## 123 # Wrapper for ET compatibility - drops the parser 124

125 -def _wrap_et_loader(loader):

126 def load(href, parse, encoding=None, parser=None): 127 return loader(href, parse, encoding)

128 return load 129 130 131 ## 132 # Expand XInclude directives. 133 # 134 # @param elem Root element. 135 # @param loader Optional resource loader. If omitted, it defaults 136 # to {@link default_loader}. If given, it should be a callable 137 # that implements the same interface as <b>default_loader</b>. 138 # @throws FatalIncludeError If the function fails to include a given 139 # resource, or if the tree contains malformed XInclude elements. 140 # @throws IOError If the function fails to load a given resource. 141 # @returns the node or its replacement if it was an XInclude node 142

143 -def include(elem, loader=None, base_url=None):

144 if base_url is None: 145 if hasattr(elem, 'getroot'): 146 tree = elem 147 elem = elem.getroot() 148 else: 149 tree = elem.getroottree() 150 if hasattr(tree, 'docinfo'): 151 base_url = tree.docinfo.URL 152 elif hasattr(elem, 'getroot'): 153 elem = elem.getroot() 154 _include(elem, loader, base_url=base_url)

155

156 -def _include(elem, loader=None, _parent_hrefs=None, base_url=None):

157 if loader is not None: 158 load_include = _wrap_et_loader(loader) 159 else: 160 load_include = _lxml_default_loader 161 162 if _parent_hrefs is None: 163 _parent_hrefs = set() 164 165 parser = elem.getroottree().parser 166 167 include_elements = list( 168 elem.getiterator('{http://www.w3.org/2001/XInclude}*')) 169 170 for e in include_elements: 171 if e.tag == XINCLUDE_INCLUDE: 172 # process xinclude directive 173 href = urljoin(base_url, e.get("href")) 174 parse = e.get("parse", "xml") 175 parent = e.getparent() 176 if parse == "xml": 177 if href in _parent_hrefs: 178 raise FatalIncludeError( 179 "recursive include of %r detected" % href 180 ) 181 _parent_hrefs.add(href) 182 node = load_include(href, parse, parser=parser) 183 if node is None: 184 raise FatalIncludeError( 185 "cannot load %r as %r" % (href, parse) 186 ) 187 node = _include(node, loader, _parent_hrefs) 188 if e.tail: 189 node.tail = (node.tail or "") + e.tail 190 if parent is None: 191 return node # replaced the root node! 192 parent.replace(e, node) 193 elif parse == "text": 194 text = load_include(href, parse, encoding=e.get("encoding")) 195 if text is None: 196 raise FatalIncludeError( 197 "cannot load %r as %r" % (href, parse) 198 ) 199 predecessor = e.getprevious() 200 if predecessor is not None: 201 predecessor.tail = (predecessor.tail or "") + text 202 elif parent is None: 203 return text # replaced the root node! 204 else: 205 parent.text = (parent.text or "") + text + (e.tail or "") 206 parent.remove(e) 207 else: 208 raise FatalIncludeError( 209 "unknown parse type in xi:include tag (%r)" % parse 210 ) 211 elif e.tag == XINCLUDE_FALLBACK: 212 parent = e.getparent() 213 if parent is not None and parent.tag != XINCLUDE_INCLUDE: 214 raise FatalIncludeError( 215 "xi:fallback tag must be child of xi:include (%r)" % e.tag 216 ) 217 else: 218 raise FatalIncludeError( 219 "Invalid element found in XInclude namespace (%r)" % e.tag 220 ) 221 return elem

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