Package lxml :: Module builder
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Source Code for Module lxml.builder

  1  # 
  2  # Element generator factory by Fredrik Lundh. 
  3  # 
  4  # Source: 
  5  #    http://online.effbot.org/2006_11_01_archive.htm#et-builder 
  6  #    http://effbot.python-hosting.com/file/stuff/sandbox/elementlib/builder.py 
  7  # 
  8  # -------------------------------------------------------------------- 
  9  # The ElementTree toolkit is 
 10  # 
 11  # Copyright (c) 1999-2004 by Fredrik Lundh 
 12  # 
 13  # By obtaining, using, and/or copying this software and/or its 
 14  # associated documentation, you agree that you have read, understood, 
 15  # and will comply with the following terms and conditions: 
 16  # 
 17  # Permission to use, copy, modify, and distribute this software and 
 18  # its associated documentation for any purpose and without fee is 
 19  # hereby granted, provided that the above copyright notice appears in 
 20  # all copies, and that both that copyright notice and this permission 
 21  # notice appear in supporting documentation, and that the name of 
 22  # Secret Labs AB or the author not be used in advertising or publicity 
 23  # pertaining to distribution of the software without specific, written 
 24  # prior permission. 
 25  # 
 26  # SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD 
 27  # TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT- 
 28  # ABILITY AND FITNESS.  IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR 
 29  # BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY 
 30  # DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, 
 31  # WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 
 32  # ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE 
 33  # OF THIS SOFTWARE. 
 34  # -------------------------------------------------------------------- 
 35   
 36  """ 
 37  The ``E`` Element factory for generating XML documents. 
 38  """ 
 39   
 40  import lxml.etree as ET 
 41   
 42  try: 
 43      from functools import partial 
 44  except ImportError: 
 45      # fake it for pre-2.5 releases 
46 - def partial(func, tag):
47 return lambda *args, **kwargs: func(tag, *args, **kwargs)
48 49 try: 50 callable 51 except NameError: 52 # Python 3
53 - def callable(f):
54 return hasattr(f, '__call__')
55 56 try: 57 basestring 58 except NameError: 59 basestring = str 60 61 try: 62 unicode 63 except NameError: 64 unicode = str 65 66
67 -class ElementMaker(object):
68 """Element generator factory. 69 70 Unlike the ordinary Element factory, the E factory allows you to pass in 71 more than just a tag and some optional attributes; you can also pass in 72 text and other elements. The text is added as either text or tail 73 attributes, and elements are inserted at the right spot. Some small 74 examples:: 75 76 >>> from lxml import etree as ET 77 >>> from lxml.builder import E 78 79 >>> ET.tostring(E("tag")) 80 '<tag/>' 81 >>> ET.tostring(E("tag", "text")) 82 '<tag>text</tag>' 83 >>> ET.tostring(E("tag", "text", key="value")) 84 '<tag key="value">text</tag>' 85 >>> ET.tostring(E("tag", E("subtag", "text"), "tail")) 86 '<tag><subtag>text</subtag>tail</tag>' 87 88 For simple tags, the factory also allows you to write ``E.tag(...)`` instead 89 of ``E('tag', ...)``:: 90 91 >>> ET.tostring(E.tag()) 92 '<tag/>' 93 >>> ET.tostring(E.tag("text")) 94 '<tag>text</tag>' 95 >>> ET.tostring(E.tag(E.subtag("text"), "tail")) 96 '<tag><subtag>text</subtag>tail</tag>' 97 98 Here's a somewhat larger example; this shows how to generate HTML 99 documents, using a mix of prepared factory functions for inline elements, 100 nested ``E.tag`` calls, and embedded XHTML fragments:: 101 102 # some common inline elements 103 A = E.a 104 I = E.i 105 B = E.b 106 107 def CLASS(v): 108 # helper function, 'class' is a reserved word 109 return {'class': v} 110 111 page = ( 112 E.html( 113 E.head( 114 E.title("This is a sample document") 115 ), 116 E.body( 117 E.h1("Hello!", CLASS("title")), 118 E.p("This is a paragraph with ", B("bold"), " text in it!"), 119 E.p("This is another paragraph, with a ", 120 A("link", href="http://www.python.org"), "."), 121 E.p("Here are some reservered characters: <spam&egg>."), 122 ET.XML("<p>And finally, here is an embedded XHTML fragment.</p>"), 123 ) 124 ) 125 ) 126 127 print ET.tostring(page) 128 129 Here's a prettyprinted version of the output from the above script:: 130 131 <html> 132 <head> 133 <title>This is a sample document</title> 134 </head> 135 <body> 136 <h1 class="title">Hello!</h1> 137 <p>This is a paragraph with <b>bold</b> text in it!</p> 138 <p>This is another paragraph, with <a href="http://www.python.org">link</a>.</p> 139 <p>Here are some reservered characters: &lt;spam&amp;egg&gt;.</p> 140 <p>And finally, here is an embedded XHTML fragment.</p> 141 </body> 142 </html> 143 144 For namespace support, you can pass a namespace map (``nsmap``) 145 and/or a specific target ``namespace`` to the ElementMaker class:: 146 147 >>> E = ElementMaker(namespace="http://my.ns/") 148 >>> print(ET.tostring( E.test )) 149 <test xmlns="http://my.ns/"/> 150 151 >>> E = ElementMaker(namespace="http://my.ns/", nsmap={'p':'http://my.ns/'}) 152 >>> print(ET.tostring( E.test )) 153 <p:test xmlns:p="http://my.ns/"/> 154 """ 155
156 - def __init__(self, typemap=None, 157 namespace=None, nsmap=None, makeelement=None):
158 if namespace is not None: 159 self._namespace = '{' + namespace + '}' 160 else: 161 self._namespace = None 162 163 if nsmap: 164 self._nsmap = dict(nsmap) 165 else: 166 self._nsmap = None 167 168 if makeelement is not None: 169 assert callable(makeelement) 170 self._makeelement = makeelement 171 else: 172 self._makeelement = ET.Element 173 174 # initialize type map for this element factory 175 176 if typemap: 177 typemap = typemap.copy() 178 else: 179 typemap = {} 180 181 def add_text(elem, item): 182 try: 183 elem[-1].tail = (elem[-1].tail or "") + item 184 except IndexError: 185 elem.text = (elem.text or "") + item
186 187 def add_cdata(elem, cdata): 188 if elem.text: 189 raise ValueError("Can't add a CDATA section. Element already has some text: %r" % elem.text) 190 elem.text = cdata
191 192 if str not in typemap: 193 typemap[str] = add_text 194 if unicode not in typemap: 195 typemap[unicode] = add_text 196 if ET.CDATA not in typemap: 197 typemap[ET.CDATA] = add_cdata 198 199 def add_dict(elem, item): 200 attrib = elem.attrib 201 for k, v in item.items(): 202 if isinstance(v, basestring): 203 attrib[k] = v 204 else: 205 attrib[k] = typemap[type(v)](None, v) 206 if dict not in typemap: 207 typemap[dict] = add_dict 208 209 self._typemap = typemap 210
211 - def __call__(self, tag, *children, **attrib):
212 get = self._typemap.get 213 214 if self._namespace is not None and tag[0] != '{': 215 tag = self._namespace + tag 216 elem = self._makeelement(tag, nsmap=self._nsmap) 217 if attrib: 218 get(dict)(elem, attrib) 219 220 for item in children: 221 if callable(item): 222 item = item() 223 t = get(type(item)) 224 if t is None: 225 if ET.iselement(item): 226 elem.append(item) 227 continue 228 for basetype in type(item).__mro__: 229 # See if the typemap knows of any of this type's bases. 230 t = get(basetype) 231 if t is not None: 232 break 233 else: 234 raise TypeError("bad argument type: %s(%r)" % 235 (type(item).__name__, item)) 236 v = t(elem, item) 237 if v: 238 get(type(v))(elem, v) 239 240 return elem
241
242 - def __getattr__(self, tag):
243 return partial(self, tag)
244 245 # create factory object 246 E = ElementMaker() 247