diff options
Diffstat (limited to 'bs4/builder/_lxml.py')
| -rw-r--r-- | bs4/builder/_lxml.py | 44 |
1 files changed, 38 insertions, 6 deletions
diff --git a/bs4/builder/_lxml.py b/bs4/builder/_lxml.py index 4a0f7de..7debf56 100644 --- a/bs4/builder/_lxml.py +++ b/bs4/builder/_lxml.py @@ -32,6 +32,10 @@ from bs4.dammit import EncodingDetector LXML = 'lxml' +def _invert(d): + "Invert a dictionary." + return dict((v,k) for k, v in d.items()) + class LXMLTreeBuilderForXML(TreeBuilder): DEFAULT_PARSER_CLASS = etree.XMLParser @@ -48,8 +52,30 @@ class LXMLTreeBuilderForXML(TreeBuilder): # This namespace mapping is specified in the XML Namespace # standard. - DEFAULT_NSMAPS = {'http://www.w3.org/XML/1998/namespace' : "xml"} + DEFAULT_NSMAPS = dict(xml='http://www.w3.org/XML/1998/namespace') + + DEFAULT_NSMAPS_INVERTED = _invert(DEFAULT_NSMAPS) + + def initialize_soup(self, soup): + """Let the BeautifulSoup object know about the standard namespace + mapping. + """ + super(LXMLTreeBuilderForXML, self).initialize_soup(soup) + self._register_namespaces(self.DEFAULT_NSMAPS) + + def _register_namespaces(self, mapping): + """Let the BeautifulSoup object know about namespaces encountered + while parsing the document. + This might be useful later on when creating CSS selectors. + """ + for key, value in mapping.items(): + if key not in self.soup._namespaces: + # Let the BeautifulSoup object know about a new namespace. + # If there are multiple namespaces defined with the same + # prefix, the first one in the document takes precedence. + self.soup._namespaces[key] = value + def default_parser(self, encoding): # This can either return a parser object or a class, which # will be instantiated with default arguments. @@ -75,8 +101,8 @@ class LXMLTreeBuilderForXML(TreeBuilder): if empty_element_tags is not None: self.empty_element_tags = set(empty_element_tags) self.soup = None - self.nsmaps = [self.DEFAULT_NSMAPS] - + self.nsmaps = [self.DEFAULT_NSMAPS_INVERTED] + def _getNsTag(self, tag): # Split the namespace URL out of a fully-qualified lxml tag # name. Copied from lxml's src/lxml/sax.py. @@ -144,7 +170,7 @@ class LXMLTreeBuilderForXML(TreeBuilder): raise ParserRejectedMarkup(str(e)) def close(self): - self.nsmaps = [self.DEFAULT_NSMAPS] + self.nsmaps = [self.DEFAULT_NSMAPS_INVERTED] def start(self, name, attrs, nsmap={}): # Make sure attrs is a mutable dict--lxml may send an immutable dictproxy. @@ -158,8 +184,14 @@ class LXMLTreeBuilderForXML(TreeBuilder): self.nsmaps.append(None) elif len(nsmap) > 0: # A new namespace mapping has come into play. - inverted_nsmap = dict((value, key) for key, value in nsmap.items()) - self.nsmaps.append(inverted_nsmap) + + # First, Let the BeautifulSoup object know about it. + self._register_namespaces(nsmap) + + # Then, add it to our running list of inverted namespace + # mappings. + self.nsmaps.append(_invert(nsmap)) + # Also treat the namespace mapping as a set of attributes on the # tag, so we can recreate it later. attrs = attrs.copy() |