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  import etree as ET 
 37   
 38  try: 
 39      from functools import partial 
 40  except ImportError: 
 41      # fake it for pre-2.5 releases 
 42 -    def partial(func, tag): 
 43          return lambda *args, **kwargs: func(tag, *args, **kwargs) 
 44   
 45   
 46 -class ElementMaker(object): 
 47      """Element generator factory. 
 48   
 49      Unlike the ordinary Element factory, the E factory allows you to pass in 
 50      more than just a tag and some optional attributes; you can also pass in 
 51      text and other elements.  The text is added as either text or tail 
 52      attributes, and elements are inserted at the right spot.  Some small 
 53      examples:: 
 54   
 55          >>> from lxml import etree as ET 
 56          >>> from lxml.builder import E 
 57   
 58          >>> ET.tostring(E("tag")) 
 59          '<tag/>' 
 60          >>> ET.tostring(E("tag", "text")) 
 61          '<tag>text</tag>' 
 62          >>> ET.tostring(E("tag", "text", key="value")) 
 63          '<tag key="value">text</tag>' 
 64          >>> ET.tostring(E("tag", E("subtag", "text"), "tail")) 
 65          '<tag><subtag>text</subtag>tail</tag>' 
 66   
 67      For simple tags, the factory also allows you to write ``E.tag(...)`` instead 
 68      of ``E('tag', ...)``:: 
 69   
 70          >>> ET.tostring(E.tag()) 
 71          '<tag/>' 
 72          >>> ET.tostring(E.tag("text")) 
 73          '<tag>text</tag>' 
 74          >>> ET.tostring(E.tag(E.subtag("text"), "tail")) 
 75          '<tag><subtag>text</subtag>tail</tag>' 
 76   
 77      Here's a somewhat larger example; this shows how to generate HTML 
 78      documents, using a mix of prepared factory functions for inline elements, 
 79      nested ``E.tag`` calls, and embedded XHTML fragments:: 
 80   
 81          # some common inline elements 
 82          A = E.a 
 83          I = E.i 
 84          B = E.b 
 85   
 86          def CLASS(v): 
 87              # helper function, 'class' is a reserved word 
 88              return {'class': v} 
 89   
 90          page = ( 
 91              E.html( 
 92                  E.head( 
 93                      E.title("This is a sample document") 
 94                  ), 
 95                  E.body( 
 96                      E.h1("Hello!", CLASS("title")), 
 97                      E.p("This is a paragraph with ", B("bold"), " text in it!"), 
 98                      E.p("This is another paragraph, with a ", 
 99                          A("link", href="http://www.python.org"), "."), 
100                      E.p("Here are some reservered characters: <spam&egg>."), 
101                      ET.XML("<p>And finally, here is an embedded XHTML fragment.</p>"), 
102                  ) 
103              ) 
104          ) 
105   
106          print ET.tostring(page) 
107   
108      Here's a prettyprinted version of the output from the above script:: 
109   
110          <html> 
111            <head> 
112              <title>This is a sample document</title> 
113            </head> 
114            <body> 
115              <h1 class="title">Hello!</h1> 
116              <p>This is a paragraph with <b>bold</b> text in it!</p> 
117              <p>This is another paragraph, with <a href="http://www.python.org">link</a>.</p> 
118              <p>Here are some reservered characters: &lt;spam&amp;egg&gt;.</p> 
119              <p>And finally, here is an embedded XHTML fragment.</p> 
120            </body> 
121          </html> 
122      """ 
123   
124 -    def __init__(self, typemap=None, 
125                   namespace=None, nsmap=None, makeelement=None): 
126          if namespace is not None: 
127              self._namespace = '{' + namespace + '}' 
128          else: 
129              self._namespace = None 
130   
131          if nsmap: 
132              self._nsmap = dict(nsmap) 
133          else: 
134              self._nsmap = None 
135   
136          if makeelement is not None: 
137              assert callable(makeelement) 
138              self._makeelement = makeelement 
139          else: 
140              self._makeelement = ET.Element 
141   
142          # initialize type map for this element factory 
143   
144          if typemap: 
145              typemap = typemap.copy() 
146          else: 
147              typemap = {} 
148           
149          def add_text(elem, item): 
150              if len(elem): 
151                  elem[-1].tail = (elem[-1].tail or "") + item 
152              else: 
153                  elem.text = (elem.text or "") + item 
154          if str not in typemap: 
155              typemap[str] = add_text 
156          if unicode not in typemap: 
157              typemap[unicode] = add_text 
158   
159          def add_dict(elem, item): 
160              attrib = elem.attrib 
161              for k, v in item.items(): 
162                  if isinstance(v, basestring): 
163                      attrib[k] = v 
164                  else: 
165                      attrib[k] = typemap[type(v)](None, v) 
166          if dict not in typemap: 
167              typemap[dict] = add_dict 
168   
169          self._typemap = typemap 
170   
171 -    def __call__(self, tag, *children, **attrib): 
172          get = self._typemap.get 
173   
174          if self._namespace is not None and tag[0] != '{': 
175              tag = self._namespace + tag 
176          elem = self._makeelement(tag, nsmap=self._nsmap) 
177          if attrib: 
178              get(dict)(elem, attrib) 
179   
180          for item in children: 
181              if callable(item): 
182                  item = item() 
183              t = get(type(item)) 
184              if t is None: 
185                  if ET.iselement(item): 
186                      elem.append(item) 
187                      continue 
188                  raise TypeError("bad argument type: %r" % item) 
189              else: 
190                  v = t(elem, item) 
191                  if v: 
192                      get(type(v))(elem, v) 
193   
194          return elem 
195   
196 -    def __getattr__(self, tag): 
197          return partial(self, tag) 
198   
199  # create factory object 
200  E = ElementMaker() 
201