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"""
XPath selectors based on lxml
"""
from lxml import etree
from scrapy.utils.misc import extract_regex
from scrapy.utils.trackref import object_ref
from scrapy.utils.python import unicode_to_str, flatten
from scrapy.utils.decorator import deprecated
from scrapy.http import HtmlResponse, XmlResponse
from .lxmldocument import LxmlDocument
from .csstranslator import ScrapyHTMLTranslator, ScrapyGenericTranslator
__all__ = ['Selector', 'SelectorList']
class SafeXMLParser(etree.XMLParser):
def __init__(self, *args, **kwargs):
kwargs.setdefault('resolve_entities', False)
super(SafeXMLParser, self).__init__(*args, **kwargs)
_ctgroup = {
'html': {'_parser': etree.HTMLParser,
'_csstranslator': ScrapyHTMLTranslator(),
'_tostring_method': 'html'},
'xml': {'_parser': SafeXMLParser,
'_csstranslator': ScrapyGenericTranslator(),
'_tostring_method': 'xml'},
}
def _st(response, st):
if st is None:
return 'xml' if isinstance(response, XmlResponse) else 'html'
elif st in ('xml', 'html'):
return st
else:
raise ValueError('Invalid type: %s' % st)
def _response_from_text(text, st):
rt = XmlResponse if st == 'xml' else HtmlResponse
return rt(url='about:blank', encoding='utf-8',
body=unicode_to_str(text, 'utf-8'))
class Selector(object_ref):
__slots__ = ['response', 'text', 'namespaces', 'type', '_expr', '_root',
'__weakref__', '_parser', '_csstranslator', '_tostring_method']
_default_type = None
_default_namespaces = {
"re": "http://exslt.org/regular-expressions",
# supported in libxslt:
# set:difference
# set:has-same-node
# set:intersection
# set:leading
# set:trailing
"set": "http://exslt.org/sets"
}
_lxml_smart_strings = False
def __init__(self, response=None, text=None, type=None, namespaces=None,
_root=None, _expr=None):
self.type = st = _st(response, type or self._default_type)
self._parser = _ctgroup[st]['_parser']
self._csstranslator = _ctgroup[st]['_csstranslator']
self._tostring_method = _ctgroup[st]['_tostring_method']
if text is not None:
response = _response_from_text(text, st)
if response is not None:
_root = LxmlDocument(response, self._parser)
self.response = response
self.namespaces = dict(self._default_namespaces)
if namespaces is not None:
self.namespaces.update(namespaces)
self._root = _root
self._expr = _expr
def xpath(self, query):
try:
xpathev = self._root.xpath
except AttributeError:
return SelectorList([])
try:
result = xpathev(query, namespaces=self.namespaces,
smart_strings=self._lxml_smart_strings)
except etree.XPathError:
raise ValueError("Invalid XPath: %s" % query)
if type(result) is not list:
result = [result]
result = [self.__class__(_root=x, _expr=query,
namespaces=self.namespaces,
type=self.type)
for x in result]
return SelectorList(result)
def css(self, query):
return self.xpath(self._css2xpath(query))
def _css2xpath(self, query):
return self._csstranslator.css_to_xpath(query)
def re(self, regex):
return extract_regex(regex, self.extract())
def extract(self):
try:
return etree.tostring(self._root,
method=self._tostring_method,
encoding=unicode,
with_tail=False)
except (AttributeError, TypeError):
if self._root is True:
return u'1'
elif self._root is False:
return u'0'
else:
return unicode(self._root)
def register_namespace(self, prefix, uri):
if self.namespaces is None:
self.namespaces = {}
self.namespaces[prefix] = uri
def remove_namespaces(self):
for el in self._root.iter('*'):
if el.tag.startswith('{'):
el.tag = el.tag.split('}', 1)[1]
# loop on element attributes also
for an in el.attrib.keys():
if an.startswith('{'):
el.attrib[an.split('}', 1)[1]] = el.attrib.pop(an)
def __nonzero__(self):
return bool(self.extract())
def __str__(self):
data = repr(self.extract()[:40])
return "<%s xpath=%r data=%s>" % (type(self).__name__, self._expr, data)
__repr__ = __str__
# Deprecated api
@deprecated(use_instead='.xpath()')
def select(self, xpath):
return self.xpath(xpath)
@deprecated(use_instead='.extract()')
def extract_unquoted(self):
return self.extract()
class SelectorList(list):
def __getslice__(self, i, j):
return self.__class__(list.__getslice__(self, i, j))
def xpath(self, xpath):
return self.__class__(flatten([x.xpath(xpath) for x in self]))
def css(self, xpath):
return self.__class__(flatten([x.css(xpath) for x in self]))
def re(self, regex):
return flatten([x.re(regex) for x in self])
def extract(self):
return [x.extract() for x in self]
@deprecated(use_instead='.extract()')
def extract_unquoted(self):
return [x.extract_unquoted() for x in self]
@deprecated(use_instead='.xpath()')
def x(self, xpath):
return self.select(xpath)
@deprecated(use_instead='.xpath()')
def select(self, xpath):
return self.xpath(xpath)
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