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 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   
 50 -class ElementMaker(object): 
 51      """Element generator factory. 
 52   
 53      Unlike the ordinary Element factory, the E factory allows you to pass in 
 54      more than just a tag and some optional attributes; you can also pass in 
 55      text and other elements.  The text is added as either text or tail 
 56      attributes, and elements are inserted at the right spot.  Some small 
 57      examples:: 
 58   
 59          >>> from lxml import etree as ET 
 60          >>> from lxml.builder import E 
 61   
 62          >>> ET.tostring(E("tag")) 
 63          '<tag/>' 
 64          >>> ET.tostring(E("tag", "text")) 
 65          '<tag>text</tag>' 
 66          >>> ET.tostring(E("tag", "text", key="value")) 
 67          '<tag key="value">text</tag>' 
 68          >>> ET.tostring(E("tag", E("subtag", "text"), "tail")) 
 69          '<tag><subtag>text</subtag>tail</tag>' 
 70   
 71      For simple tags, the factory also allows you to write ``E.tag(...)`` instead 
 72      of ``E('tag', ...)``:: 
 73   
 74          >>> ET.tostring(E.tag()) 
 75          '<tag/>' 
 76          >>> ET.tostring(E.tag("text")) 
 77          '<tag>text</tag>' 
 78          >>> ET.tostring(E.tag(E.subtag("text"), "tail")) 
 79          '<tag><subtag>text</subtag>tail</tag>' 
 80   
 81      Here's a somewhat larger example; this shows how to generate HTML 
 82      documents, using a mix of prepared factory functions for inline elements, 
 83      nested ``E.tag`` calls, and embedded XHTML fragments:: 
 84   
 85          # some common inline elements 
 86          A = E.a 
 87          I = E.i 
 88          B = E.b 
 89   
 90          def CLASS(v): 
 91              # helper function, 'class' is a reserved word 
 92              return {'class': v} 
 93   
 94          page = ( 
 95              E.html( 
 96                  E.head( 
 97                      E.title("This is a sample document") 
 98                  ), 
 99                  E.body( 
100                      E.h1("Hello!", CLASS("title")), 
101                      E.p("This is a paragraph with ", B("bold"), " text in it!"), 
102                      E.p("This is another paragraph, with a ", 
103                          A("link", href="http://www.python.org"), "."), 
104                      E.p("Here are some reservered characters: <spam&egg>."), 
105                      ET.XML("<p>And finally, here is an embedded XHTML fragment.</p>"), 
106                  ) 
107              ) 
108          ) 
109   
110          print ET.tostring(page) 
111   
112      Here's a prettyprinted version of the output from the above script:: 
113   
114          <html> 
115            <head> 
116              <title>This is a sample document</title> 
117            </head> 
118            <body> 
119              <h1 class="title">Hello!</h1> 
120              <p>This is a paragraph with <b>bold</b> text in it!</p> 
121              <p>This is another paragraph, with <a href="http://www.python.org">link</a>.</p> 
122              <p>Here are some reservered characters: &lt;spam&amp;egg&gt;.</p> 
123              <p>And finally, here is an embedded XHTML fragment.</p> 
124            </body> 
125          </html> 
126      """ 
127   
128 -    def __init__(self, typemap=None, 
129                   namespace=None, nsmap=None, makeelement=None): 
130          if namespace is not None: 
131              self._namespace = '{' + namespace + '}' 
132          else: 
133              self._namespace = None 
134   
135          if nsmap: 
136              self._nsmap = dict(nsmap) 
137          else: 
138              self._nsmap = None 
139   
140          if makeelement is not None: 
141              assert callable(makeelement) 
142              self._makeelement = makeelement 
143          else: 
144              self._makeelement = ET.Element 
145   
146          # initialize type map for this element factory 
147   
148          if typemap: 
149              typemap = typemap.copy() 
150          else: 
151              typemap = {} 
152           
153          def add_text(elem, item): 
154              if len(elem): 
155                  elem[-1].tail = (elem[-1].tail or "") + item 
156              else: 
157                  elem.text = (elem.text or "") + item 
158          if str not in typemap: 
159              typemap[str] = add_text 
160          if unicode not in typemap: 
161              typemap[unicode] = add_text 
162   
163          def add_dict(elem, item): 
164              attrib = elem.attrib 
165              for k, v in item.items(): 
166                  if isinstance(v, basestring): 
167                      attrib[k] = v 
168                  else: 
169                      attrib[k] = typemap[type(v)](None, v) 
170          if dict not in typemap: 
171              typemap[dict] = add_dict 
172   
173          self._typemap = typemap 
174   
175 -    def __call__(self, tag, *children, **attrib): 
176          get = self._typemap.get 
177   
178          if self._namespace is not None and tag[0] != '{': 
179              tag = self._namespace + tag 
180          elem = self._makeelement(tag, nsmap=self._nsmap) 
181          if attrib: 
182              get(dict)(elem, attrib) 
183   
184          for item in children: 
185              if callable(item): 
186                  item = item() 
187              t = get(type(item)) 
188              if t is None: 
189                  if ET.iselement(item): 
190                      elem.append(item) 
191                      continue 
192                  raise TypeError("bad argument type: %r" % item) 
193              else: 
194                  v = t(elem, item) 
195                  if v: 
196                      get(type(v))(elem, v) 
197   
198          return elem 
199   
200 -    def __getattr__(self, tag): 
201          return partial(self, tag) 
202   
203  # create factory object 
204  E = ElementMaker() 
205