368 lines
12 KiB
Python
368 lines
12 KiB
Python
"""\
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A library of useful helper classes to the SAX classes, for the
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convenience of application and driver writers.
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"""
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import os, urllib.parse, urllib.request
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import io
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import codecs
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from . import handler
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from . import xmlreader
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def __dict_replace(s, d):
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"""Replace substrings of a string using a dictionary."""
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for key, value in d.items():
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s = s.replace(key, value)
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return s
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def escape(data, entities={}):
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"""Escape &, <, and > in a string of data.
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You can escape other strings of data by passing a dictionary as
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the optional entities parameter. The keys and values must all be
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strings; each key will be replaced with its corresponding value.
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"""
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# must do ampersand first
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data = data.replace("&", "&")
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data = data.replace(">", ">")
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data = data.replace("<", "<")
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if entities:
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data = __dict_replace(data, entities)
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return data
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def unescape(data, entities={}):
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"""Unescape &, <, and > in a string of data.
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You can unescape other strings of data by passing a dictionary as
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the optional entities parameter. The keys and values must all be
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strings; each key will be replaced with its corresponding value.
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"""
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data = data.replace("<", "<")
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data = data.replace(">", ">")
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if entities:
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data = __dict_replace(data, entities)
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# must do ampersand last
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return data.replace("&", "&")
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def quoteattr(data, entities={}):
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"""Escape and quote an attribute value.
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Escape &, <, and > in a string of data, then quote it for use as
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an attribute value. The \" character will be escaped as well, if
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necessary.
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You can escape other strings of data by passing a dictionary as
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the optional entities parameter. The keys and values must all be
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strings; each key will be replaced with its corresponding value.
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"""
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entities = entities.copy()
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entities.update({'\n': ' ', '\r': ' ', '\t':'	'})
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data = escape(data, entities)
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if '"' in data:
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if "'" in data:
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data = '"%s"' % data.replace('"', """)
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else:
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data = "'%s'" % data
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else:
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data = '"%s"' % data
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return data
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def _gettextwriter(out, encoding):
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if out is None:
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import sys
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return sys.stdout
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if isinstance(out, io.TextIOBase):
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# use a text writer as is
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return out
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if isinstance(out, (codecs.StreamWriter, codecs.StreamReaderWriter)):
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# use a codecs stream writer as is
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return out
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# wrap a binary writer with TextIOWrapper
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if isinstance(out, io.RawIOBase):
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# Keep the original file open when the TextIOWrapper is
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# destroyed
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class _wrapper:
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__class__ = out.__class__
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def __getattr__(self, name):
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return getattr(out, name)
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buffer = _wrapper()
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buffer.close = lambda: None
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else:
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# This is to handle passed objects that aren't in the
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# IOBase hierarchy, but just have a write method
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buffer = io.BufferedIOBase()
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buffer.writable = lambda: True
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buffer.write = out.write
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try:
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# TextIOWrapper uses this methods to determine
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# if BOM (for UTF-16, etc) should be added
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buffer.seekable = out.seekable
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buffer.tell = out.tell
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except AttributeError:
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pass
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return io.TextIOWrapper(buffer, encoding=encoding,
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errors='xmlcharrefreplace',
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newline='\n',
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write_through=True)
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class XMLGenerator(handler.ContentHandler):
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def __init__(self, out=None, encoding="iso-8859-1", short_empty_elements=False):
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handler.ContentHandler.__init__(self)
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out = _gettextwriter(out, encoding)
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self._write = out.write
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self._flush = out.flush
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self._ns_contexts = [{}] # contains uri -> prefix dicts
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self._current_context = self._ns_contexts[-1]
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self._undeclared_ns_maps = []
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self._encoding = encoding
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self._short_empty_elements = short_empty_elements
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self._pending_start_element = False
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def _qname(self, name):
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"""Builds a qualified name from a (ns_url, localname) pair"""
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if name[0]:
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# Per http://www.w3.org/XML/1998/namespace, The 'xml' prefix is
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# bound by definition to http://www.w3.org/XML/1998/namespace. It
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# does not need to be declared and will not usually be found in
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# self._current_context.
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if 'http://www.w3.org/XML/1998/namespace' == name[0]:
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return 'xml:' + name[1]
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# The name is in a non-empty namespace
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prefix = self._current_context[name[0]]
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if prefix:
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# If it is not the default namespace, prepend the prefix
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return prefix + ":" + name[1]
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# Return the unqualified name
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return name[1]
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def _finish_pending_start_element(self,endElement=False):
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if self._pending_start_element:
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self._write('>')
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self._pending_start_element = False
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# ContentHandler methods
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def startDocument(self):
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self._write('<?xml version="1.0" encoding="%s"?>\n' %
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self._encoding)
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def endDocument(self):
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self._flush()
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def startPrefixMapping(self, prefix, uri):
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self._ns_contexts.append(self._current_context.copy())
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self._current_context[uri] = prefix
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self._undeclared_ns_maps.append((prefix, uri))
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def endPrefixMapping(self, prefix):
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self._current_context = self._ns_contexts[-1]
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del self._ns_contexts[-1]
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def startElement(self, name, attrs):
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self._finish_pending_start_element()
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self._write('<' + name)
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for (name, value) in attrs.items():
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self._write(' %s=%s' % (name, quoteattr(value)))
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if self._short_empty_elements:
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self._pending_start_element = True
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else:
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self._write(">")
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def endElement(self, name):
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if self._pending_start_element:
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self._write('/>')
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self._pending_start_element = False
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else:
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self._write('</%s>' % name)
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def startElementNS(self, name, qname, attrs):
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self._finish_pending_start_element()
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self._write('<' + self._qname(name))
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for prefix, uri in self._undeclared_ns_maps:
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if prefix:
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self._write(' xmlns:%s="%s"' % (prefix, uri))
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else:
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self._write(' xmlns="%s"' % uri)
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self._undeclared_ns_maps = []
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for (name, value) in attrs.items():
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self._write(' %s=%s' % (self._qname(name), quoteattr(value)))
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if self._short_empty_elements:
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self._pending_start_element = True
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else:
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self._write(">")
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def endElementNS(self, name, qname):
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if self._pending_start_element:
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self._write('/>')
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self._pending_start_element = False
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else:
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self._write('</%s>' % self._qname(name))
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def characters(self, content):
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if content:
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self._finish_pending_start_element()
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if not isinstance(content, str):
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content = str(content, self._encoding)
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self._write(escape(content))
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def ignorableWhitespace(self, content):
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if content:
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self._finish_pending_start_element()
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if not isinstance(content, str):
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content = str(content, self._encoding)
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self._write(content)
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def processingInstruction(self, target, data):
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self._finish_pending_start_element()
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self._write('<?%s %s?>' % (target, data))
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class XMLFilterBase(xmlreader.XMLReader):
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"""This class is designed to sit between an XMLReader and the
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client application's event handlers. By default, it does nothing
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but pass requests up to the reader and events on to the handlers
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unmodified, but subclasses can override specific methods to modify
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the event stream or the configuration requests as they pass
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through."""
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def __init__(self, parent = None):
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xmlreader.XMLReader.__init__(self)
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self._parent = parent
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# ErrorHandler methods
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def error(self, exception):
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self._err_handler.error(exception)
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def fatalError(self, exception):
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self._err_handler.fatalError(exception)
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def warning(self, exception):
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self._err_handler.warning(exception)
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# ContentHandler methods
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def setDocumentLocator(self, locator):
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self._cont_handler.setDocumentLocator(locator)
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def startDocument(self):
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self._cont_handler.startDocument()
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def endDocument(self):
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self._cont_handler.endDocument()
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def startPrefixMapping(self, prefix, uri):
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self._cont_handler.startPrefixMapping(prefix, uri)
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def endPrefixMapping(self, prefix):
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self._cont_handler.endPrefixMapping(prefix)
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def startElement(self, name, attrs):
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self._cont_handler.startElement(name, attrs)
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def endElement(self, name):
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self._cont_handler.endElement(name)
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def startElementNS(self, name, qname, attrs):
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self._cont_handler.startElementNS(name, qname, attrs)
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def endElementNS(self, name, qname):
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self._cont_handler.endElementNS(name, qname)
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def characters(self, content):
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self._cont_handler.characters(content)
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def ignorableWhitespace(self, chars):
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self._cont_handler.ignorableWhitespace(chars)
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def processingInstruction(self, target, data):
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self._cont_handler.processingInstruction(target, data)
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def skippedEntity(self, name):
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self._cont_handler.skippedEntity(name)
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# DTDHandler methods
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def notationDecl(self, name, publicId, systemId):
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self._dtd_handler.notationDecl(name, publicId, systemId)
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def unparsedEntityDecl(self, name, publicId, systemId, ndata):
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self._dtd_handler.unparsedEntityDecl(name, publicId, systemId, ndata)
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# EntityResolver methods
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def resolveEntity(self, publicId, systemId):
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return self._ent_handler.resolveEntity(publicId, systemId)
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# XMLReader methods
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def parse(self, source):
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self._parent.setContentHandler(self)
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self._parent.setErrorHandler(self)
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self._parent.setEntityResolver(self)
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self._parent.setDTDHandler(self)
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self._parent.parse(source)
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def setLocale(self, locale):
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self._parent.setLocale(locale)
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def getFeature(self, name):
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return self._parent.getFeature(name)
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def setFeature(self, name, state):
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self._parent.setFeature(name, state)
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def getProperty(self, name):
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return self._parent.getProperty(name)
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def setProperty(self, name, value):
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self._parent.setProperty(name, value)
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# XMLFilter methods
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def getParent(self):
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return self._parent
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def setParent(self, parent):
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self._parent = parent
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# --- Utility functions
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def prepare_input_source(source, base=""):
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"""This function takes an InputSource and an optional base URL and
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returns a fully resolved InputSource object ready for reading."""
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if isinstance(source, str):
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source = xmlreader.InputSource(source)
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elif hasattr(source, "read"):
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f = source
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source = xmlreader.InputSource()
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if isinstance(f.read(0), str):
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source.setCharacterStream(f)
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else:
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source.setByteStream(f)
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if hasattr(f, "name") and isinstance(f.name, str):
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source.setSystemId(f.name)
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if source.getCharacterStream() is None and source.getByteStream() is None:
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sysid = source.getSystemId()
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basehead = os.path.dirname(os.path.normpath(base))
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sysidfilename = os.path.join(basehead, sysid)
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if os.path.isfile(sysidfilename):
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source.setSystemId(sysidfilename)
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f = open(sysidfilename, "rb")
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else:
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source.setSystemId(urllib.parse.urljoin(base, sysid))
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f = urllib.request.urlopen(source.getSystemId())
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source.setByteStream(f)
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return source
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