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 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

71 -class FatalIncludeError(etree.LxmlSyntaxError):

72 pass

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

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

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

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

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

121 -def _wrap_et_loader(loader):

122 def load(href, parse, encoding=None, parser=None): 123 return loader(href, parse, encoding)

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 # @param base_url The base URL of the original file, to resolve 135 # relative include file references. 136 # @throws FatalIncludeError If the function fails to include a given 137 # resource, or if the tree contains malformed XInclude elements. 138 # @throws IOError If the function fails to load a given resource. 139 # @returns the node or its replacement if it was an XInclude node 140

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

142 if base_url is None: 143 if hasattr(elem, 'getroot'): 144 tree = elem 145 elem = elem.getroot() 146 else: 147 tree = elem.getroottree() 148 if hasattr(tree, 'docinfo'): 149 base_url = tree.docinfo.URL 150 elif hasattr(elem, 'getroot'): 151 elem = elem.getroot() 152 _include(elem, loader, base_url=base_url)

153

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

155 if loader is not None: 156 load_include = _wrap_et_loader(loader) 157 else: 158 load_include = _lxml_default_loader 159 160 if _parent_hrefs is None: 161 _parent_hrefs = set() 162 163 parser = elem.getroottree().parser 164 165 include_elements = list( 166 elem.iter(XINCLUDE_ITER_TAG)) 167 168 for e in include_elements: 169 if e.tag == XINCLUDE_INCLUDE: 170 # process xinclude directive 171 href = urljoin(base_url, e.get("href")) 172 parse = e.get("parse", "xml") 173 parent = e.getparent() 174 if parse == "xml": 175 if href in _parent_hrefs: 176 raise FatalIncludeError( 177 "recursive include of %r detected" % href 178 ) 179 _parent_hrefs.add(href) 180 node = load_include(href, parse, parser=parser) 181 if node is None: 182 raise FatalIncludeError( 183 "cannot load %r as %r" % (href, parse) 184 ) 185 node = _include(node, loader, _parent_hrefs) 186 if e.tail: 187 node.tail = (node.tail or "") + e.tail 188 if parent is None: 189 return node # replaced the root node! 190 parent.replace(e, node) 191 elif parse == "text": 192 text = load_include(href, parse, encoding=e.get("encoding")) 193 if text is None: 194 raise FatalIncludeError( 195 "cannot load %r as %r" % (href, parse) 196 ) 197 predecessor = e.getprevious() 198 if predecessor is not None: 199 predecessor.tail = (predecessor.tail or "") + text 200 elif parent is None: 201 return text # replaced the root node! 202 else: 203 parent.text = (parent.text or "") + text + (e.tail or "") 204 parent.remove(e) 205 else: 206 raise FatalIncludeError( 207 "unknown parse type in xi:include tag (%r)" % parse 208 ) 209 elif e.tag == XINCLUDE_FALLBACK: 210 parent = e.getparent() 211 if parent is not None and parent.tag != XINCLUDE_INCLUDE: 212 raise FatalIncludeError( 213 "xi:fallback tag must be child of xi:include (%r)" % e.tag 214 ) 215 else: 216 raise FatalIncludeError( 217 "Invalid element found in XInclude namespace (%r)" % e.tag 218 ) 219 return elem

220