246 lines
8 KiB
Python
246 lines
8 KiB
Python
#
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# Element generator factory by Fredrik Lundh.
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#
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# Source:
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# http://online.effbot.org/2006_11_01_archive.htm#et-builder
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# http://effbot.python-hosting.com/file/stuff/sandbox/elementlib/builder.py
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#
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# --------------------------------------------------------------------
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# The ElementTree toolkit is
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#
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# Copyright (c) 1999-2004 by Fredrik Lundh
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#
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# By obtaining, using, and/or copying this software and/or its
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# associated documentation, you agree that you have read, understood,
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# and will comply with the following terms and conditions:
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#
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# Permission to use, copy, modify, and distribute this software and
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# its associated documentation for any purpose and without fee is
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# hereby granted, provided that the above copyright notice appears in
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# all copies, and that both that copyright notice and this permission
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# notice appear in supporting documentation, and that the name of
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# Secret Labs AB or the author not be used in advertising or publicity
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# pertaining to distribution of the software without specific, written
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# prior permission.
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#
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# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
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# TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT-
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# ABILITY AND FITNESS. IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR
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# BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
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# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
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# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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# OF THIS SOFTWARE.
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# --------------------------------------------------------------------
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"""
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The ``E`` Element factory for generating XML documents.
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"""
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import lxml.etree as ET
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try:
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from functools import partial
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except ImportError:
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# fake it for pre-2.5 releases
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def partial(func, tag):
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return lambda *args, **kwargs: func(tag, *args, **kwargs)
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try:
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callable
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except NameError:
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# Python 3
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def callable(f):
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return hasattr(f, '__call__')
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try:
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basestring
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except NameError:
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basestring = str
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try:
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unicode
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except NameError:
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unicode = str
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class ElementMaker(object):
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"""Element generator factory.
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Unlike the ordinary Element factory, the E factory allows you to pass in
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more than just a tag and some optional attributes; you can also pass in
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text and other elements. The text is added as either text or tail
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attributes, and elements are inserted at the right spot. Some small
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examples::
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>>> from lxml import etree as ET
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>>> from lxml.builder import E
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>>> ET.tostring(E("tag"))
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'<tag/>'
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>>> ET.tostring(E("tag", "text"))
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'<tag>text</tag>'
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>>> ET.tostring(E("tag", "text", key="value"))
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'<tag key="value">text</tag>'
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>>> ET.tostring(E("tag", E("subtag", "text"), "tail"))
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'<tag><subtag>text</subtag>tail</tag>'
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For simple tags, the factory also allows you to write ``E.tag(...)`` instead
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of ``E('tag', ...)``::
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>>> ET.tostring(E.tag())
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'<tag/>'
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>>> ET.tostring(E.tag("text"))
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'<tag>text</tag>'
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>>> ET.tostring(E.tag(E.subtag("text"), "tail"))
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'<tag><subtag>text</subtag>tail</tag>'
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Here's a somewhat larger example; this shows how to generate HTML
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documents, using a mix of prepared factory functions for inline elements,
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nested ``E.tag`` calls, and embedded XHTML fragments::
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# some common inline elements
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A = E.a
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I = E.i
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B = E.b
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def CLASS(v):
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# helper function, 'class' is a reserved word
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return {'class': v}
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page = (
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E.html(
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E.head(
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E.title("This is a sample document")
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),
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E.body(
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E.h1("Hello!", CLASS("title")),
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E.p("This is a paragraph with ", B("bold"), " text in it!"),
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E.p("This is another paragraph, with a ",
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A("link", href="http://www.python.org"), "."),
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E.p("Here are some reservered characters: <spam&egg>."),
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ET.XML("<p>And finally, here is an embedded XHTML fragment.</p>"),
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)
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)
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)
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print ET.tostring(page)
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Here's a prettyprinted version of the output from the above script::
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<html>
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<head>
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<title>This is a sample document</title>
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</head>
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<body>
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<h1 class="title">Hello!</h1>
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<p>This is a paragraph with <b>bold</b> text in it!</p>
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<p>This is another paragraph, with <a href="http://www.python.org">link</a>.</p>
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<p>Here are some reservered characters: <spam&egg>.</p>
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<p>And finally, here is an embedded XHTML fragment.</p>
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</body>
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</html>
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For namespace support, you can pass a namespace map (``nsmap``)
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and/or a specific target ``namespace`` to the ElementMaker class::
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>>> E = ElementMaker(namespace="http://my.ns/")
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>>> print(ET.tostring( E.test ))
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<test xmlns="http://my.ns/"/>
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>>> E = ElementMaker(namespace="http://my.ns/", nsmap={'p':'http://my.ns/'})
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>>> print(ET.tostring( E.test ))
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<p:test xmlns:p="http://my.ns/"/>
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"""
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def __init__(self, typemap=None,
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namespace=None, nsmap=None, makeelement=None):
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if namespace is not None:
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self._namespace = '{' + namespace + '}'
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else:
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self._namespace = None
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if nsmap:
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self._nsmap = dict(nsmap)
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else:
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self._nsmap = None
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if makeelement is not None:
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assert callable(makeelement)
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self._makeelement = makeelement
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else:
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self._makeelement = ET.Element
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# initialize type map for this element factory
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if typemap:
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typemap = typemap.copy()
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else:
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typemap = {}
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def add_text(elem, item):
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try:
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elem[-1].tail = (elem[-1].tail or "") + item
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except IndexError:
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elem.text = (elem.text or "") + item
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def add_cdata(elem, cdata):
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if elem.text:
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raise ValueError("Can't add a CDATA section. Element already has some text: %r" % elem.text)
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elem.text = cdata
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if str not in typemap:
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typemap[str] = add_text
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if unicode not in typemap:
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typemap[unicode] = add_text
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if ET.CDATA not in typemap:
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typemap[ET.CDATA] = add_cdata
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def add_dict(elem, item):
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attrib = elem.attrib
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for k, v in item.items():
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if isinstance(v, basestring):
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attrib[k] = v
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else:
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attrib[k] = typemap[type(v)](None, v)
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if dict not in typemap:
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typemap[dict] = add_dict
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self._typemap = typemap
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def __call__(self, tag, *children, **attrib):
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get = self._typemap.get
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if self._namespace is not None and tag[0] != '{':
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tag = self._namespace + tag
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elem = self._makeelement(tag, nsmap=self._nsmap)
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if attrib:
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get(dict)(elem, attrib)
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for item in children:
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if callable(item):
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item = item()
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t = get(type(item))
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if t is None:
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if ET.iselement(item):
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elem.append(item)
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continue
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for basetype in type(item).__mro__:
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# See if the typemap knows of any of this type's bases.
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t = get(basetype)
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if t is not None:
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break
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else:
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raise TypeError("bad argument type: %s(%r)" %
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(type(item).__name__, item))
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v = t(elem, item)
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if v:
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get(type(v))(elem, v)
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return elem
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def __getattr__(self, tag):
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return partial(self, tag)
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# create factory object
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E = ElementMaker()
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