Current File : //lib/python3/dist-packages/twisted/words/xish/domish.py
# -*- test-case-name: twisted.words.test.test_domish -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
DOM-like XML processing support.
This module provides support for parsing XML into DOM-like object structures
and serializing such structures to an XML string representation, optimized
for use in streaming XML applications.
"""
from typing import cast
from zope.interface import Attribute, Interface, implementer
from twisted.web import sux
def _splitPrefix(name):
"""Internal method for splitting a prefixed Element name into its
respective parts"""
ntok = name.split(":", 1)
if len(ntok) == 2:
return ntok
else:
return (None, ntok[0])
# Global map of prefixes that always get injected
# into the serializers prefix map (note, that doesn't
# mean they're always _USED_)
G_PREFIXES = {"http://www.w3.org/XML/1998/namespace": "xml"}
class _ListSerializer:
"""Internal class which serializes an Element tree into a buffer"""
def __init__(self, prefixes=None, prefixesInScope=None):
self.writelist = []
self.prefixes = {}
if prefixes:
self.prefixes.update(prefixes)
self.prefixes.update(G_PREFIXES)
self.prefixStack = [G_PREFIXES.values()] + (prefixesInScope or [])
self.prefixCounter = 0
def getValue(self):
return "".join(self.writelist)
def getPrefix(self, uri):
if uri not in self.prefixes:
self.prefixes[uri] = "xn%d" % (self.prefixCounter)
self.prefixCounter = self.prefixCounter + 1
return self.prefixes[uri]
def prefixInScope(self, prefix):
stack = self.prefixStack
for i in range(-1, (len(self.prefixStack) + 1) * -1, -1):
if prefix in stack[i]:
return True
return False
def serialize(self, elem, closeElement=1, defaultUri=""):
# Optimization shortcuts
write = self.writelist.append
# Shortcut, check to see if elem is actually a chunk o' serialized XML
if isinstance(elem, SerializedXML):
write(elem)
return
# Shortcut, check to see if elem is actually a string (aka Cdata)
if isinstance(elem, str):
write(escapeToXml(elem))
return
# Further optimizations
name = elem.name
uri = elem.uri
defaultUri, currentDefaultUri = elem.defaultUri, defaultUri
for p, u in elem.localPrefixes.items():
self.prefixes[u] = p
self.prefixStack.append(list(elem.localPrefixes.keys()))
# Inherit the default namespace
if defaultUri is None:
defaultUri = currentDefaultUri
if uri is None:
uri = defaultUri
prefix = None
if uri != defaultUri or uri in self.prefixes:
prefix = self.getPrefix(uri)
inScope = self.prefixInScope(prefix)
# Create the starttag
if not prefix:
write("<%s" % (name))
else:
write(f"<{prefix}:{name}")
if not inScope:
write(f" xmlns:{prefix}='{uri}'")
self.prefixStack[-1].append(prefix)
inScope = True
if defaultUri != currentDefaultUri and (
uri != defaultUri or not prefix or not inScope
):
write(" xmlns='%s'" % (defaultUri))
for p, u in elem.localPrefixes.items():
write(f" xmlns:{p}='{u}'")
# Serialize attributes
for k, v in elem.attributes.items():
# If the attribute name is a tuple, it's a qualified attribute
if isinstance(k, tuple):
attr_uri, attr_name = k
attr_prefix = self.getPrefix(attr_uri)
if not self.prefixInScope(attr_prefix):
write(f" xmlns:{attr_prefix}='{attr_uri}'")
self.prefixStack[-1].append(attr_prefix)
write(f" {attr_prefix}:{attr_name}='{escapeToXml(v, 1)}'")
else:
write(f" {k}='{escapeToXml(v, 1)}'")
# Shortcut out if this is only going to return
# the element (i.e. no children)
if closeElement == 0:
write(">")
return
# Serialize children
if len(elem.children) > 0:
write(">")
for c in elem.children:
self.serialize(c, defaultUri=defaultUri)
# Add closing tag
if not prefix:
write("</%s>" % (name))
else:
write(f"</{prefix}:{name}>")
else:
write("/>")
self.prefixStack.pop()
SerializerClass = _ListSerializer
def escapeToXml(text, isattrib=0):
"""Escape text to proper XML form, per section 2.3 in the XML specification.
@type text: C{str}
@param text: Text to escape
@type isattrib: C{bool}
@param isattrib: Triggers escaping of characters necessary for use as
attribute values
"""
text = text.replace("&", "&")
text = text.replace("<", "<")
text = text.replace(">", ">")
if isattrib == 1:
text = text.replace("'", "'")
text = text.replace('"', """)
return text
def unescapeFromXml(text):
text = text.replace("<", "<")
text = text.replace(">", ">")
text = text.replace("'", "'")
text = text.replace(""", '"')
text = text.replace("&", "&")
return text
def generateOnlyInterface(list, int):
"""Filters items in a list by class"""
for n in list:
if int.providedBy(n):
yield n
def generateElementsQNamed(list, name, uri):
"""Filters Element items in a list with matching name and URI."""
for n in list:
if IElement.providedBy(n) and n.name == name and n.uri == uri:
yield n
def generateElementsNamed(list, name):
"""Filters Element items in a list with matching name, regardless of URI."""
for n in list:
if IElement.providedBy(n) and n.name == name:
yield n
class SerializedXML(str):
"""Marker class for pre-serialized XML in the DOM."""
pass
class Namespace:
"""Convenience object for tracking namespace declarations."""
def __init__(self, uri):
self._uri = uri
def __getattr__(self, n):
return (self._uri, n)
def __getitem__(self, n):
return (self._uri, n)
class IElement(Interface):
"""
Interface to XML element nodes.
See L{Element} for a detailed example of its general use.
Warning: this Interface is not yet complete!
"""
uri = Attribute(""" Element's namespace URI """)
name = Attribute(""" Element's local name """)
defaultUri = Attribute(""" Default namespace URI of child elements """)
attributes = Attribute(""" Dictionary of element attributes """)
children = Attribute(""" List of child nodes """)
parent = Attribute(""" Reference to element's parent element """)
localPrefixes = Attribute(""" Dictionary of local prefixes """)
def toXml(prefixes=None, closeElement=1, defaultUri="", prefixesInScope=None):
"""Serializes object to a (partial) XML document
@param prefixes: dictionary that maps namespace URIs to suggested
prefix names.
@type prefixes: L{dict}
@param closeElement: flag that determines whether to include the
closing tag of the element in the serialized string. A value of
C{0} only generates the element's start tag. A value of C{1} yields
a complete serialization.
@type closeElement: L{int}
@param defaultUri: Initial default namespace URI. This is most useful
for partial rendering, where the logical parent element (of which
the starttag was already serialized) declares a default namespace
that should be inherited.
@type defaultUri: L{str}
@param prefixesInScope: list of prefixes that are assumed to be
declared by ancestors.
@type prefixesInScope: L{list}
@return: (partial) serialized XML
@rtype: L{str}
"""
def addElement(name, defaultUri=None, content=None):
"""
Create an element and add as child.
The new element is added to this element as a child, and will have
this element as its parent.
@param name: element name. This can be either a L{str} object that
contains the local name, or a tuple of (uri, local_name) for a
fully qualified name. In the former case, the namespace URI is
inherited from this element.
@type name: L{str} or L{tuple} of (L{str}, L{str})
@param defaultUri: default namespace URI for child elements. If
L{None}, this is inherited from this element.
@type defaultUri: L{str}
@param content: text contained by the new element.
@type content: L{str}
@return: the created element
@rtype: object providing L{IElement}
"""
def addChild(node):
"""
Adds a node as child of this element.
The C{node} will be added to the list of childs of this element, and
will have this element set as its parent when C{node} provides
L{IElement}. If C{node} is a L{str} and the current last child is
character data (L{str}), the text from C{node} is appended to the
existing last child.
@param node: the child node.
@type node: L{str} or object implementing L{IElement}
"""
def addContent(text):
"""
Adds character data to this element.
If the current last child of this element is a string, the text will
be appended to that string. Otherwise, the text will be added as a new
child.
@param text: The character data to be added to this element.
@type text: L{str}
"""
@implementer(IElement)
class Element:
"""Represents an XML element node.
An Element contains a series of attributes (name/value pairs), content
(character data), and other child Element objects. When building a document
with markup (such as HTML or XML), use this object as the starting point.
Element objects fully support XML Namespaces. The fully qualified name of
the XML Element it represents is stored in the C{uri} and C{name}
attributes, where C{uri} holds the namespace URI. There is also a default
namespace, for child elements. This is stored in the C{defaultUri}
attribute. Note that C{''} means the empty namespace.
Serialization of Elements through C{toXml()} will use these attributes
for generating proper serialized XML. When both C{uri} and C{defaultUri}
are not None in the Element and all of its descendents, serialization
proceeds as expected:
>>> from twisted.words.xish import domish
>>> root = domish.Element(('myns', 'root'))
>>> root.addElement('child', content='test')
<twisted.words.xish.domish.Element object at 0x83002ac>
>>> root.toXml()
u"<root xmlns='myns'><child>test</child></root>"
For partial serialization, needed for streaming XML, a special value for
namespace URIs can be used: L{None}.
Using L{None} as the value for C{uri} means: this element is in whatever
namespace inherited by the closest logical ancestor when the complete XML
document has been serialized. The serialized start tag will have a
non-prefixed name, and no xmlns declaration will be generated.
Similarly, L{None} for C{defaultUri} means: the default namespace for my
child elements is inherited from the logical ancestors of this element,
when the complete XML document has been serialized.
To illustrate, an example from a Jabber stream. Assume the start tag of the
root element of the stream has already been serialized, along with several
complete child elements, and sent off, looking like this::
<stream:stream xmlns:stream='http://etherx.jabber.org/streams'
xmlns='jabber:client' to='example.com'>
...
Now suppose we want to send a complete element represented by an
object C{message} created like:
>>> message = domish.Element((None, 'message'))
>>> message['to'] = 'user@example.com'
>>> message.addElement('body', content='Hi!')
<twisted.words.xish.domish.Element object at 0x8276e8c>
>>> message.toXml()
u"<message to='user@example.com'><body>Hi!</body></message>"
As, you can see, this XML snippet has no xmlns declaration. When sent
off, it inherits the C{jabber:client} namespace from the root element.
Note that this renders the same as using C{''} instead of L{None}:
>>> presence = domish.Element(('', 'presence'))
>>> presence.toXml()
u"<presence/>"
However, if this object has a parent defined, the difference becomes
clear:
>>> child = message.addElement(('http://example.com/', 'envelope'))
>>> child.addChild(presence)
<twisted.words.xish.domish.Element object at 0x8276fac>
>>> message.toXml()
u"<message to='user@example.com'><body>Hi!</body><envelope xmlns='http://example.com/'><presence xmlns=''/></envelope></message>"
As, you can see, the <presence/> element is now in the empty namespace, not
in the default namespace of the parent or the streams'.
@type uri: L{str} or None
@ivar uri: URI of this Element's name
@type name: L{str}
@ivar name: Name of this Element
@type defaultUri: L{str} or None
@ivar defaultUri: URI this Element exists within
@type children: L{list}
@ivar children: List of child Elements and content
@type parent: L{Element}
@ivar parent: Reference to the parent Element, if any.
@type attributes: L{dict}
@ivar attributes: Dictionary of attributes associated with this Element.
@type localPrefixes: L{dict}
@ivar localPrefixes: Dictionary of namespace declarations on this
element. The key is the prefix to bind the
namespace uri to.
"""
_idCounter = 0
def __init__(self, qname, defaultUri=None, attribs=None, localPrefixes=None):
"""
@param qname: Tuple of (uri, name)
@param defaultUri: The default URI of the element; defaults to the URI
specified in C{qname}
@param attribs: Dictionary of attributes
@param localPrefixes: Dictionary of namespace declarations on this
element. The key is the prefix to bind the
namespace uri to.
"""
self.localPrefixes = localPrefixes or {}
self.uri, self.name = qname
if defaultUri is None and self.uri not in self.localPrefixes.values():
self.defaultUri = self.uri
else:
self.defaultUri = defaultUri
self.attributes = attribs or {}
self.children = []
self.parent = None
def __getattr__(self, key):
# Check child list for first Element with a name matching the key
for n in self.children:
if IElement.providedBy(n) and n.name == key:
return n
# Tweak the behaviour so that it's more friendly about not
# finding elements -- we need to document this somewhere :)
if key.startswith("_"):
raise AttributeError(key)
else:
return None
def __getitem__(self, key):
return self.attributes[self._dqa(key)]
def __delitem__(self, key):
del self.attributes[self._dqa(key)]
def __setitem__(self, key, value):
self.attributes[self._dqa(key)] = value
def __unicode__(self):
"""
Retrieve the first CData (content) node
"""
for n in self.children:
if isinstance(n, str):
return n
return ""
def __bytes__(self):
"""
Retrieve the first character data node as UTF-8 bytes.
"""
return str(self).encode("utf-8")
__str__ = __unicode__
def _dqa(self, attr):
"""Dequalify an attribute key as needed"""
if isinstance(attr, tuple) and not attr[0]:
return attr[1]
else:
return attr
def getAttribute(self, attribname, default=None):
"""Retrieve the value of attribname, if it exists"""
return self.attributes.get(attribname, default)
def hasAttribute(self, attrib):
"""Determine if the specified attribute exists"""
return self._dqa(attrib) in self.attributes
def compareAttribute(self, attrib, value):
"""Safely compare the value of an attribute against a provided value.
L{None}-safe.
"""
return self.attributes.get(self._dqa(attrib), None) == value
def swapAttributeValues(self, left, right):
"""Swap the values of two attribute."""
d = self.attributes
l = d[left]
d[left] = d[right]
d[right] = l
def addChild(self, node):
"""Add a child to this Element."""
if IElement.providedBy(node):
node.parent = self
self.children.append(node)
return node
def addContent(self, text: str) -> str:
"""Add some text data to this Element."""
if not isinstance(text, str):
raise TypeError(f"Expected str not {text!r} ({type(text).__name__})")
c = self.children
if len(c) > 0 and isinstance(c[-1], str):
c[-1] = c[-1] + text
else:
c.append(text)
return cast(str, c[-1])
def addElement(self, name, defaultUri=None, content=None):
if isinstance(name, tuple):
if defaultUri is None:
defaultUri = name[0]
child = Element(name, defaultUri)
else:
if defaultUri is None:
defaultUri = self.defaultUri
child = Element((defaultUri, name), defaultUri)
self.addChild(child)
if content:
child.addContent(content)
return child
def addRawXml(self, rawxmlstring):
"""Add a pre-serialized chunk o' XML as a child of this Element."""
self.children.append(SerializedXML(rawxmlstring))
def addUniqueId(self):
"""Add a unique (across a given Python session) id attribute to this
Element.
"""
self.attributes["id"] = "H_%d" % Element._idCounter
Element._idCounter = Element._idCounter + 1
def elements(self, uri=None, name=None):
"""
Iterate across all children of this Element that are Elements.
Returns a generator over the child elements. If both the C{uri} and
C{name} parameters are set, the returned generator will only yield
on elements matching the qualified name.
@param uri: Optional element URI.
@type uri: L{str}
@param name: Optional element name.
@type name: L{str}
@return: Iterator that yields objects implementing L{IElement}.
"""
if name is None:
return generateOnlyInterface(self.children, IElement)
else:
return generateElementsQNamed(self.children, name, uri)
def toXml(self, prefixes=None, closeElement=1, defaultUri="", prefixesInScope=None):
"""Serialize this Element and all children to a string."""
s = SerializerClass(prefixes=prefixes, prefixesInScope=prefixesInScope)
s.serialize(self, closeElement=closeElement, defaultUri=defaultUri)
return s.getValue()
def firstChildElement(self):
for c in self.children:
if IElement.providedBy(c):
return c
return None
class ParserError(Exception):
"""Exception thrown when a parsing error occurs"""
pass
def elementStream():
"""Preferred method to construct an ElementStream
Uses Expat-based stream if available, and falls back to Sux if necessary.
"""
try:
es = ExpatElementStream()
return es
except ImportError:
if SuxElementStream is None:
raise Exception("No parsers available :(")
es = SuxElementStream()
return es
class SuxElementStream(sux.XMLParser):
def __init__(self):
self.connectionMade()
self.DocumentStartEvent = None
self.ElementEvent = None
self.DocumentEndEvent = None
self.currElem = None
self.rootElem = None
self.documentStarted = False
self.defaultNsStack = []
self.prefixStack = []
def parse(self, buffer):
try:
self.dataReceived(buffer)
except sux.ParseError as e:
raise ParserError(str(e))
def findUri(self, prefix):
# Walk prefix stack backwards, looking for the uri
# matching the specified prefix
stack = self.prefixStack
for i in range(-1, (len(self.prefixStack) + 1) * -1, -1):
if prefix in stack[i]:
return stack[i][prefix]
return None
def gotTagStart(self, name, attributes):
defaultUri = None
localPrefixes = {}
attribs = {}
uri = None
# Pass 1 - Identify namespace decls
for k, v in list(attributes.items()):
if k.startswith("xmlns"):
x, p = _splitPrefix(k)
if x is None: # I.e. default declaration
defaultUri = v
else:
localPrefixes[p] = v
del attributes[k]
# Push namespace decls onto prefix stack
self.prefixStack.append(localPrefixes)
# Determine default namespace for this element; if there
# is one
if defaultUri is None:
if len(self.defaultNsStack) > 0:
defaultUri = self.defaultNsStack[-1]
else:
defaultUri = ""
# Fix up name
prefix, name = _splitPrefix(name)
if prefix is None: # This element is in the default namespace
uri = defaultUri
else:
# Find the URI for the prefix
uri = self.findUri(prefix)
# Pass 2 - Fix up and escape attributes
for k, v in attributes.items():
p, n = _splitPrefix(k)
if p is None:
attribs[n] = v
else:
attribs[(self.findUri(p)), n] = unescapeFromXml(v)
# Construct the actual Element object
e = Element((uri, name), defaultUri, attribs, localPrefixes)
# Save current default namespace
self.defaultNsStack.append(defaultUri)
# Document already started
if self.documentStarted:
# Starting a new packet
if self.currElem is None:
self.currElem = e
# Adding to existing element
else:
self.currElem = self.currElem.addChild(e)
# New document
else:
self.rootElem = e
self.documentStarted = True
self.DocumentStartEvent(e)
def gotText(self, data):
if self.currElem is not None:
if isinstance(data, bytes):
data = data.decode("ascii")
self.currElem.addContent(data)
def gotCData(self, data):
if self.currElem is not None:
if isinstance(data, bytes):
data = data.decode("ascii")
self.currElem.addContent(data)
def gotComment(self, data):
# Ignore comments for the moment
pass
entities = {
"amp": "&",
"lt": "<",
"gt": ">",
"apos": "'",
"quot": '"',
}
def gotEntityReference(self, entityRef):
# If this is an entity we know about, add it as content
# to the current element
if entityRef in SuxElementStream.entities:
data = SuxElementStream.entities[entityRef]
if isinstance(data, bytes):
data = data.decode("ascii")
self.currElem.addContent(data)
def gotTagEnd(self, name):
# Ensure the document hasn't already ended
if self.rootElem is None:
# XXX: Write more legible explanation
raise ParserError("Element closed after end of document.")
# Fix up name
prefix, name = _splitPrefix(name)
if prefix is None:
uri = self.defaultNsStack[-1]
else:
uri = self.findUri(prefix)
# End of document
if self.currElem is None:
# Ensure element name and uri matches
if self.rootElem.name != name or self.rootElem.uri != uri:
raise ParserError("Mismatched root elements")
self.DocumentEndEvent()
self.rootElem = None
# Other elements
else:
# Ensure the tag being closed matches the name of the current
# element
if self.currElem.name != name or self.currElem.uri != uri:
# XXX: Write more legible explanation
raise ParserError("Malformed element close")
# Pop prefix and default NS stack
self.prefixStack.pop()
self.defaultNsStack.pop()
# Check for parent null parent of current elem;
# that's the top of the stack
if self.currElem.parent is None:
self.currElem.parent = self.rootElem
self.ElementEvent(self.currElem)
self.currElem = None
# Anything else is just some element wrapping up
else:
self.currElem = self.currElem.parent
class ExpatElementStream:
def __init__(self):
import pyexpat
self.DocumentStartEvent = None
self.ElementEvent = None
self.DocumentEndEvent = None
self.error = pyexpat.error
self.parser = pyexpat.ParserCreate("UTF-8", " ")
self.parser.StartElementHandler = self._onStartElement
self.parser.EndElementHandler = self._onEndElement
self.parser.CharacterDataHandler = self._onCdata
self.parser.StartNamespaceDeclHandler = self._onStartNamespace
self.parser.EndNamespaceDeclHandler = self._onEndNamespace
self.currElem = None
self.defaultNsStack = [""]
self.documentStarted = 0
self.localPrefixes = {}
def parse(self, buffer):
try:
self.parser.Parse(buffer)
except self.error as e:
raise ParserError(str(e))
def _onStartElement(self, name, attrs):
# Generate a qname tuple from the provided name. See
# http://docs.python.org/library/pyexpat.html#xml.parsers.expat.ParserCreate
# for an explanation of the formatting of name.
qname = name.rsplit(" ", 1)
if len(qname) == 1:
qname = ("", name)
# Process attributes
newAttrs = {}
toDelete = []
for k, v in attrs.items():
if " " in k:
aqname = k.rsplit(" ", 1)
newAttrs[(aqname[0], aqname[1])] = v
toDelete.append(k)
attrs.update(newAttrs)
for k in toDelete:
del attrs[k]
# Construct the new element
e = Element(qname, self.defaultNsStack[-1], attrs, self.localPrefixes)
self.localPrefixes = {}
# Document already started
if self.documentStarted == 1:
if self.currElem != None:
self.currElem.children.append(e)
e.parent = self.currElem
self.currElem = e
# New document
else:
self.documentStarted = 1
self.DocumentStartEvent(e)
def _onEndElement(self, _):
# Check for null current elem; end of doc
if self.currElem is None:
self.DocumentEndEvent()
# Check for parent that is None; that's
# the top of the stack
elif self.currElem.parent is None:
self.ElementEvent(self.currElem)
self.currElem = None
# Anything else is just some element in the current
# packet wrapping up
else:
self.currElem = self.currElem.parent
def _onCdata(self, data):
if self.currElem != None:
self.currElem.addContent(data)
def _onStartNamespace(self, prefix, uri):
# If this is the default namespace, put
# it on the stack
if prefix is None:
self.defaultNsStack.append(uri)
else:
self.localPrefixes[prefix] = uri
def _onEndNamespace(self, prefix):
# Remove last element on the stack
if prefix is None:
self.defaultNsStack.pop()
## class FileParser(ElementStream):
## def __init__(self):
## ElementStream.__init__(self)
## self.DocumentStartEvent = self.docStart
## self.ElementEvent = self.elem
## self.DocumentEndEvent = self.docEnd
## self.done = 0
## def docStart(self, elem):
## self.document = elem
## def elem(self, elem):
## self.document.addChild(elem)
## def docEnd(self):
## self.done = 1
## def parse(self, filename):
## with open(filename) as f:
## for l in f.readlines():
## self.parser.Parse(l)
## assert self.done == 1
## return self.document
## def parseFile(filename):
## return FileParser().parse(filename)
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