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ElementTree.py
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"""Lightweight XML support for Python. XML is an inherently hierarchical data format, and the most natural way to represent it is with a tree. This module has two classes for this purpose: 1. ElementTree represents the whole XML document as a tree and 2. Element represents a single node in this tree. Interactions with the whole document (reading and writing to/from files) are usually done on the ElementTree level. Interactions with a single XML element and its sub-elements are done on the Element level. Element is a flexible container object designed to store hierarchical data structures in memory. It can be described as a cross between a list and a dictionary. Each Element has a number of properties associated with it: 'tag' - a string containing the element's name. 'attributes' - a Python dictionary storing the element's attributes. 'text' - a string containing the element's text content. 'tail' - an optional string containing text after the element's end tag. And a number of child elements stored in a Python sequence. To create an element instance, use the Element constructor, or the SubElement factory function. You can also use the ElementTree class to wrap an element structure and convert it to and from XML. """ #--------------------------------------------------------------------- # Licensed to PSF under a Contributor Agreement. # See http://www.python.org/psf/license for licensing details. # # ElementTree # Copyright (c) 1999-2008 by Fredrik Lundh. All rights reserved. # # fredrik@pythonware.com # http://www.pythonware.com # -------------------------------------------------------------------- # The ElementTree toolkit is # # Copyright (c) 1999-2008 by Fredrik Lundh # # By obtaining, using, and/or copying this software and/or its # associated documentation, you agree that you have read, understood, # and will comply with the following terms and conditions: # # Permission to use, copy, modify, and distribute this software and # its associated documentation for any purpose and without fee is # hereby granted, provided that the above copyright notice appears in # all copies, and that both that copyright notice and this permission # notice appear in supporting documentation, and that the name of # Secret Labs AB or the author not be used in advertising or publicity # pertaining to distribution of the software without specific, written # prior permission. # # SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD # TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANT- # ABILITY AND FITNESS. IN NO EVENT SHALL SECRET LABS AB OR THE AUTHOR # BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY # DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, # WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS # ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE # OF THIS SOFTWARE. # -------------------------------------------------------------------- __all__ = [ # public symbols "Comment", "dump", "Element", "ElementTree", "fromstring", "fromstringlist", "iselement", "iterparse", "parse", "ParseError", "PI", "ProcessingInstruction", "QName", "SubElement", "tostring", "tostringlist", "TreeBuilder", "VERSION", "XML", "XMLID", "XMLParser", "register_namespace", ] VERSION = "1.3.0" import sys import re import warnings import io import contextlib from . import ElementPath class ParseError(SyntaxError): """An error when parsing an XML document. In addition to its exception value, a ParseError contains two extra attributes: 'code' - the specific exception code 'position' - the line and column of the error """ pass # -------------------------------------------------------------------- def iselement(element): """Return True if *element* appears to be an Element.""" return hasattr(element, 'tag') class Element: """An XML element. This class is the reference implementation of the Element interface. An element's length is its number of subelements. That means if you want to check if an element is truly empty, you should check BOTH its length AND its text attribute. The element tag, attribute names, and attribute values can be either bytes or strings. *tag* is the element name. *attrib* is an optional dictionary containing element attributes. *extra* are additional element attributes given as keyword arguments. Example form: <tag attrib>text<child/>...</tag>tail """ tag = None """The element's name.""" attrib = None """Dictionary of the element's attributes.""" text = None """ Text before first subelement. This is either a string or the value None. Note that if there is no text, this attribute may be either None or the empty string, depending on the parser. """ tail = None """ Text after this element's end tag, but before the next sibling element's start tag. This is either a string or the value None. Note that if there was no text, this attribute may be either None or an empty string, depending on the parser. """ def __init__(self, tag, attrib={}, **extra): if not isinstance(attrib, dict): raise TypeError("attrib must be dict, not %s" % ( attrib.__class__.__name__,)) attrib = attrib.copy() attrib.update(extra) self.tag = tag self.attrib = attrib self._children = [] def __repr__(self): return "<%s %r at %#x>" % (self.__class__.__name__, self.tag, id(self)) def makeelement(self, tag, attrib): """Create a new element with the same type. *tag* is a string containing the element name. *attrib* is a dictionary containing the element attributes. Do not call this method, use the SubElement factory function instead. """ return self.__class__(tag, attrib) def copy(self): """Return copy of current element. This creates a shallow copy. Subelements will be shared with the original tree. """ elem = self.makeelement(self.tag, self.attrib) elem.text = self.text elem.tail = self.tail elem[:] = self return elem def __len__(self): return len(self._children) def __bool__(self): warnings.warn( "The behavior of this method will change in future versions. " "Use specific 'len(elem)' or 'elem is not None' test instead.", FutureWarning, stacklevel=2 ) return len(self._children) != 0 # emulate old behaviour, for now def __getitem__(self, index): return self._children[index] def __setitem__(self, index, element): # if isinstance(index, slice): # for elt in element: # assert iselement(elt) # else: # assert iselement(element) self._children[index] = element def __delitem__(self, index): del self._children[index] def append(self, subelement): """Add *subelement* to the end of this element. The new element will appear in document order after the last existing subelement (or directly after the text, if it's the first subelement), but before the end tag for this element. """ self._assert_is_element(subelement) self._children.append(subelement) def extend(self, elements): """Append subelements from a sequence. *elements* is a sequence with zero or more elements. """ for element in elements: self._assert_is_element(element) self._children.extend(elements) def insert(self, index, subelement): """Insert *subelement* at position *index*.""" self._assert_is_element(subelement) self._children.insert(index, subelement) def _assert_is_element(self, e): # Need to refer to the actual Python implementation, not the # shadowing C implementation. if not isinstance(e, _Element_Py): raise TypeError('expected an Element, not %s' % type(e).__name__) def remove(self, subelement): """Remove matching subelement. Unlike the find methods, this method compares elements based on identity, NOT ON tag value or contents. To remove subelements by other means, the easiest way is to use a list comprehension to select what elements to keep, and then use slice assignment to update the parent element. ValueError is raised if a matching element could not be found. """ # assert iselement(element) self._children.remove(subelement) def getchildren(self): """(Deprecated) Return all subelements. Elements are returned in document order. """ warnings.warn( "This method will be removed in future versions. " "Use 'list(elem)' or iteration over elem instead.", DeprecationWarning, stacklevel=2 ) return self._children def find(self, path, namespaces=None): """Find first matching element by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return the first matching element, or None if no element was found. """ return ElementPath.find(self, path, namespaces) def findtext(self, path, default=None, namespaces=None): """Find text for first matching element by tag name or path. *path* is a string having either an element tag or an XPath, *default* is the value to return if the element was not found, *namespaces* is an optional mapping from namespace prefix to full name. Return text content of first matching element, or default value if none was found. Note that if an element is found having no text content, the empty string is returned. """ return ElementPath.findtext(self, path, default, namespaces) def findall(self, path, namespaces=None): """Find all matching subelements by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Returns list containing all matching elements in document order. """ return ElementPath.findall(self, path, namespaces) def iterfind(self, path, namespaces=None): """Find all matching subelements by tag name or path. *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return an iterable yielding all matching elements in document order. """ return ElementPath.iterfind(self, path, namespaces) def clear(self): """Reset element. This function removes all subelements, clears all attributes, and sets the text and tail attributes to None. """ self.attrib.clear() self._children = [] self.text = self.tail = None def get(self, key, default=None): """Get element attribute. Equivalent to attrib.get, but some implementations may handle this a bit more efficiently. *key* is what attribute to look for, and *default* is what to return if the attribute was not found. Returns a string containing the attribute value, or the default if attribute was not found. """ return self.attrib.get(key, default) def set(self, key, value): """Set element attribute. Equivalent to attrib[key] = value, but some implementations may handle this a bit more efficiently. *key* is what attribute to set, and *value* is the attribute value to set it to. """ self.attrib[key] = value def keys(self): """Get list of attribute names. Names are returned in an arbitrary order, just like an ordinary Python dict. Equivalent to attrib.keys() """ return self.attrib.keys() def items(self): """Get element attributes as a sequence. The attributes are returned in arbitrary order. Equivalent to attrib.items(). Return a list of (name, value) tuples. """ return self.attrib.items() def iter(self, tag=None): """Create tree iterator. The iterator loops over the element and all subelements in document order, returning all elements with a matching tag. If the tree structure is modified during iteration, new or removed elements may or may not be included. To get a stable set, use the list() function on the iterator, and loop over the resulting list. *tag* is what tags to look for (default is to return all elements) Return an iterator containing all the matching elements. """ if tag == "*": tag = None if tag is None or self.tag == tag: yield self for e in self._children: yield from e.iter(tag) # compatibility def getiterator(self, tag=None): # Change for a DeprecationWarning in 1.4 warnings.warn( "This method will be removed in future versions. " "Use 'elem.iter()' or 'list(elem.iter())' instead.", PendingDeprecationWarning, stacklevel=2 ) return list(self.iter(tag)) def itertext(self): """Create text iterator. The iterator loops over the element and all subelements in document order, returning all inner text. """ tag = self.tag if not isinstance(tag, str) and tag is not None: return t = self.text if t: yield t for e in self: yield from e.itertext() t = e.tail if t: yield t def SubElement(parent, tag, attrib={}, **extra): """Subelement factory which creates an element instance, and appends it to an existing parent. The element tag, attribute names, and attribute values can be either bytes or Unicode strings. *parent* is the parent element, *tag* is the subelements name, *attrib* is an optional directory containing element attributes, *extra* are additional attributes given as keyword arguments. """ attrib = attrib.copy() attrib.update(extra) element = parent.makeelement(tag, attrib) parent.append(element) return element def Comment(text=None): """Comment element factory. This function creates a special element which the standard serializer serializes as an XML comment. *text* is a string containing the comment string. """ element = Element(Comment) element.text = text return element def ProcessingInstruction(target, text=None): """Processing Instruction element factory. This function creates a special element which the standard serializer serializes as an XML comment. *target* is a string containing the processing instruction, *text* is a string containing the processing instruction contents, if any. """ element = Element(ProcessingInstruction) element.text = target if text: element.text = element.text + " " + text return element PI = ProcessingInstruction class QName: """Qualified name wrapper. This class can be used to wrap a QName attribute value in order to get proper namespace handing on output. *text_or_uri* is a string containing the QName value either in the form {uri}local, or if the tag argument is given, the URI part of a QName. *tag* is an optional argument which if given, will make the first argument (text_or_uri) be interpreted as a URI, and this argument (tag) be interpreted as a local name. """ def __init__(self, text_or_uri, tag=None): if tag: text_or_uri = "{%s}%s" % (text_or_uri, tag) self.text = text_or_uri def __str__(self): return self.text def __repr__(self): return '<%s %r>' % (self.__class__.__name__, self.text) def __hash__(self): return hash(self.text) def __le__(self, other): if isinstance(other, QName): return self.text <= other.text return self.text <= other def __lt__(self, other): if isinstance(other, QName): return self.text < other.text return self.text < other def __ge__(self, other): if isinstance(other, QName): return self.text >= other.text return self.text >= other def __gt__(self, other): if isinstance(other, QName): return self.text > other.text return self.text > other def __eq__(self, other): if isinstance(other, QName): return self.text == other.text return self.text == other # -------------------------------------------------------------------- class ElementTree: """An XML element hierarchy. This class also provides support for serialization to and from standard XML. *element* is an optional root element node, *file* is an optional file handle or file name of an XML file whose contents will be used to initialize the tree with. """ def __init__(self, element=None, file=None): # assert element is None or iselement(element) self._root = element # first node if file: self.parse(file) def getroot(self): """Return root element of this tree.""" return self._root def _setroot(self, element): """Replace root element of this tree. This will discard the current contents of the tree and replace it with the given element. Use with care! """ # assert iselement(element) self._root = element def parse(self, source, parser=None): """Load external XML document into element tree. *source* is a file name or file object, *parser* is an optional parser instance that defaults to XMLParser. ParseError is raised if the parser fails to parse the document. Returns the root element of the given source document. """ close_source = False if not hasattr(source, "read"): source = open(source, "rb") close_source = True try: if parser is None: # If no parser was specified, create a default XMLParser parser = XMLParser() if hasattr(parser, '_parse_whole'): # The default XMLParser, when it comes from an accelerator, # can define an internal _parse_whole API for efficiency. # It can be used to parse the whole source without feeding # it with chunks. self._root = parser._parse_whole(source) return self._root while True: data = source.read(65536) if not data: break parser.feed(data) self._root = parser.close() return self._root finally: if close_source: source.close() def iter(self, tag=None): """Create and return tree iterator for the root element. The iterator loops over all elements in this tree, in document order. *tag* is a string with the tag name to iterate over (default is to return all elements). """ # assert self._root is not None return self._root.iter(tag) # compatibility def getiterator(self, tag=None): # Change for a DeprecationWarning in 1.4 warnings.warn( "This method will be removed in future versions. " "Use 'tree.iter()' or 'list(tree.iter())' instead.", PendingDeprecationWarning, stacklevel=2 ) return list(self.iter(tag)) def find(self, path, namespaces=None): """Find first matching element by tag name or path. Same as getroot().find(path), which is Element.find() *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return the first matching element, or None if no element was found. """ # assert self._root is not None if path[:1] == "/": path = "." + path warnings.warn( "This search is broken in 1.3 and earlier, and will be " "fixed in a future version. If you rely on the current " "behaviour, change it to %r" % path, FutureWarning, stacklevel=2 ) return self._root.find(path, namespaces) def findtext(self, path, default=None, namespaces=None): """Find first matching element by tag name or path. Same as getroot().findtext(path), which is Element.findtext() *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return the first matching element, or None if no element was found. """ # assert self._root is not None if path[:1] == "/": path = "." + path warnings.warn( "This search is broken in 1.3 and earlier, and will be " "fixed in a future version. If you rely on the current " "behaviour, change it to %r" % path, FutureWarning, stacklevel=2 ) return self._root.findtext(path, default, namespaces) def findall(self, path, namespaces=None): """Find all matching subelements by tag name or path. Same as getroot().findall(path), which is Element.findall(). *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return list containing all matching elements in document order. """ # assert self._root is not None if path[:1] == "/": path = "." + path warnings.warn( "This search is broken in 1.3 and earlier, and will be " "fixed in a future version. If you rely on the current " "behaviour, change it to %r" % path, FutureWarning, stacklevel=2 ) return self._root.findall(path, namespaces) def iterfind(self, path, namespaces=None): """Find all matching subelements by tag name or path. Same as getroot().iterfind(path), which is element.iterfind() *path* is a string having either an element tag or an XPath, *namespaces* is an optional mapping from namespace prefix to full name. Return an iterable yielding all matching elements in document order. """ # assert self._root is not None if path[:1] == "/": path = "." + path warnings.warn( "This search is broken in 1.3 and earlier, and will be " "fixed in a future version. If you rely on the current " "behaviour, change it to %r" % path, FutureWarning, stacklevel=2 ) return self._root.iterfind(path, namespaces) def write(self, file_or_filename, encoding=None, xml_declaration=None, default_namespace=None, method=None, *, short_empty_elements=True): """Write element tree to a file as XML. Arguments: *file_or_filename* -- file name or a file object opened for writing *encoding* -- the output encoding (default: US-ASCII) *xml_declaration* -- bool indicating if an XML declaration should be added to the output. If None, an XML declaration is added if encoding IS NOT either of: US-ASCII, UTF-8, or Unicode *default_namespace* -- sets the default XML namespace (for "xmlns") *method* -- either "xml" (default), "html, "text", or "c14n" *short_empty_elements* -- controls the formatting of elements that contain no content. If True (default) they are emitted as a single self-closed tag, otherwise they are emitted as a pair of start/end tags """ if not method: method = "xml" elif method not in _serialize: raise ValueError("unknown method %r" % method) if not encoding: if method == "c14n": encoding = "utf-8" else: encoding = "us-ascii" enc_lower = encoding.lower() with _get_writer(file_or_filename, enc_lower) as write: if method == "xml" and (xml_declaration or (xml_declaration is None and enc_lower not in ("utf-8", "us-ascii", "unicode"))): declared_encoding = encoding if enc_lower == "unicode": # Retrieve the default encoding for the xml declaration import locale declared_encoding = locale.getpreferredencoding() write("<?xml version='1.0' encoding='%s'?>\n" % ( declared_encoding,)) if method == "text": _serialize_text(write, self._root) else: qnames, namespaces = _namespaces(self._root, default_namespace) serialize = _serialize[method] serialize(write, self._root, qnames, namespaces, short_empty_elements=short_empty_elements) def write_c14n(self, file): # lxml.etree compatibility. use output method instead return self.write(file, method="c14n") # -------------------------------------------------------------------- # serialization support @contextlib.contextmanager def _get_writer(file_or_filename, encoding): # returns text write method and release all resources after using try: write = file_or_filename.write except AttributeError: # file_or_filename is a file name if encoding == "unicode": file = open(file_or_filename, "w") else: file = open(file_or_filename, "w", encoding=encoding, errors="xmlcharrefreplace") with file: yield file.write else: # file_or_filename is a file-like object # encoding determines if it is a text or binary writer if encoding == "unicode": # use a text writer as is yield write else: # wrap a binary writer with TextIOWrapper with contextlib.ExitStack() as stack: if isinstance(file_or_filename, io.BufferedIOBase): file = file_or_filename elif isinstance(file_or_filename, io.RawIOBase): file = io.BufferedWriter(file_or_filename) # Keep the original file open when the BufferedWriter is # destroyed stack.callback(file.detach) else: # This is to handle passed objects that aren't in the # IOBase hierarchy, but just have a write method file = io.BufferedIOBase() file.writable = lambda: True file.write = write try: # TextIOWrapper uses this methods to determine # if BOM (for UTF-16, etc) should be added file.seekable = file_or_filename.seekable file.tell = file_or_filename.tell except AttributeError: pass file = io.TextIOWrapper(file, encoding=encoding, errors="xmlcharrefreplace", newline="\n") # Keep the original file open when the TextIOWrapper is # destroyed stack.callback(file.detach) yield file.write def _namespaces(elem, default_namespace=None): # identify namespaces used in this tree # maps qnames to *encoded* prefix:local names qnames = {None: None} # maps uri:s to prefixes namespaces = {} if default_namespace: namespaces[default_namespace] = "" def add_qname(qname): # calculate serialized qname representation try: if qname[:1] == "{": uri, tag = qname[1:].rsplit("}", 1) prefix = namespaces.get(uri) if prefix is None: prefix = _namespace_map.get(uri) if prefix is None: prefix = "ns%d" % len(namespaces) if prefix != "xml": namespaces[uri] = prefix if prefix: qnames[qname] = "%s:%s" % (prefix, tag) else: qnames[qname] = tag # default element else: if default_namespace: # FIXME: can this be handled in XML 1.0? raise ValueError( "cannot use non-qualified names with " "default_namespace option" ) qnames[qname] = qname except TypeError: _raise_serialization_error(qname) # populate qname and namespaces table for elem in elem.iter(): tag = elem.tag if isinstance(tag, QName): if tag.text not in qnames: add_qname(tag.text) elif isinstance(tag, str): if tag not in qnames: add_qname(tag) elif tag is not None and tag is not Comment and tag is not PI: _raise_serialization_error(tag) for key, value in elem.items(): if isinstance(key, QName): key = key.text if key not in qnames: add_qname(key) if isinstance(value, QName) and value.text not in qnames: add_qname(value.text) text = elem.text if isinstance(text, QName) and text.text not in qnames: add_qname(text.text) return qnames, namespaces def _serialize_xml(write, elem, qnames, namespaces, short_empty_elements, **kwargs): tag = elem.tag text = elem.text if tag is Comment: write("<!--%s-->" % text) elif tag is ProcessingInstruction: write("<?%s?>" % text) else: tag = qnames[tag] if tag is None: if text: write(_escape_cdata(text)) for e in elem: _serialize_xml(write, e, qnames, None, short_empty_elements=short_empty_elements) else: write("<" + tag) items = list(elem.items()) if items or namespaces: if namespaces: for v, k in sorted(namespaces.items(), key=lambda x: x[1]): # sort on prefix if k: k = ":" + k write(" xmlns%s=\"%s\"" % ( k, _escape_attrib(v) )) for k, v in sorted(items): # lexical order if isinstance(k, QName): k = k.text if isinstance(v, QName): v = qnames[v.text] else: v = _escape_attrib(v) write(" %s=\"%s\"" % (qnames[k], v)) if text or len(elem) or not short_empty_elements: write(">") if text: write(_escape_cdata(text)) for e in elem: _serialize_xml(write, e, qnames, None, short_empty_elements=short_empty_elements) write("</" + tag + ">") else: write(" />") if elem.tail: write(_escape_cdata(elem.tail)) HTML_EMPTY = ("area", "base", "basefont", "br", "col", "frame", "hr", "img", "input", "isindex", "link", "meta", "param") try: HTML_EMPTY = set(HTML_EMPTY) except NameError: pass def _serialize_html(write, elem, qnames, namespaces, **kwargs): tag = elem.tag text = elem.text if tag is Comment: write("<!--%s-->" % _escape_cdata(text)) elif tag is ProcessingInstruction: write("<?%s?>" % _escape_cdata(text)) else: tag = qnames[tag] if tag is None: if text: write(_escape_cdata(text)) for e in elem: _serialize_html(write, e, qnames, None) else: write("<" + tag) items = list(elem.items()) if items or namespaces: if namespaces: for v, k in sorted(namespaces.items(), key=lambda x: x[1]): # sort on prefix if k: k = ":" + k write(" xmlns%s=\"%s\"" % ( k, _escape_attrib(v) )) for k, v in sorted(items): # lexical order if isinstance(k, QName): k = k.text if isinstance(v, QName): v = qnames[v.text] else: v = _escape_attrib_html(v) # FIXME: handle boolean attributes write(" %s=\"%s\"" % (qnames[k], v)) write(">") ltag = tag.lower() if text: if ltag == "script" or ltag == "style": write(text) else: write(_escape_cdata(text)) for e in elem: _serialize_html(write, e, qnames, None) if ltag not in HTML_EMPTY: write("</" + tag + ">") if elem.tail: write(_escape_cdata(elem.tail)) def _serialize_text(write, elem): for part in elem.itertext(): write(part) if elem.tail: write(elem.tail) _serialize = { "xml": _serialize_xml, "html": _serialize_html, "text": _serialize_text, # this optional method is imported at the end of the module # "c14n": _serialize_c14n, } def register_namespace(prefix, uri): """Register a namespace prefix. The registry is global, and any existing mapping for either the given prefix or the namespace URI will be removed. *prefix* is the namespace prefix, *uri* is a namespace uri. Tags and attributes in this namespace will be serialized with prefix if possible. ValueError is raised if prefix is reserved or is invalid. """ if re.match("ns\d+$", prefix): raise ValueError("Prefix format reserved for internal use") for k, v in list(_namespace_map.items()): if k == uri or v == prefix: del _namespace_map[k] _namespace_map[uri] = prefix _namespace_map = { # "well-known" namespace prefixes "http://www.w3.org/XML/1998/namespace": "xml", "http://www.w3.org/1999/xhtml": "html", "http://www.w3.org/1999/02/22-rdf-syntax-ns#": "rdf", "http://schemas.xmlsoap.org/wsdl/": "wsdl", # xml schema "http://www.w3.org/2001/XMLSchema": "xs", "http://www.w3.org/2001/XMLSchema-instance": "xsi", # dublin core "http://purl.org/dc/elements/1.1/": "dc", } # For tests and troubleshooting register_namespace._namespace_map = _namespace_map def _raise_serialization_error(text): raise TypeError( "cannot serialize %r (type %s)" % (text, type(text).__name__) ) def _escape_cdata(text): # escape character data try: # it's worth avoiding do-nothing calls for strings that are # shorter than 500 character, or so. assume that's, by far, # the most common case in most applications. if "&" in text: text = text.replace("&", "&") if "<" in text: text = text.replace("<", "<") if ">" in text: text = text.replace(">", ">") return text except (TypeError, AttributeError): _raise_serialization_error(text) def _escape_attrib(text): # escape attribute value try: if "&" in text: text = text.replace("&", "&") if "<" in text: text = text.replace("<", "<") if ">" in text: text = text.replace(">", ">") if "\"" in text: text = text.replace("\"", """) # The following business with carriage returns is to satisfy # Section 2.11 of the XML specification, stating that # CR or CR LN should be replaced with just LN # http://www.w3.org/TR/REC-xml/#sec-line-ends if "\r\n" in text: text = text.replace("\r\n", "\n") if "\r" in text: text = text.replace("\r", "\n") #The following four lines are issue 17582 if "\n" in text: text = text.replace("\n", " ") if "\t" in text: text = text.replace("\t", "	") return text except (TypeError, AttributeError): _raise_serialization_error(text) def _escape_attrib_html(text): # escape attribute value try: if "&" in text: text = text.replace("&", "&") if ">" in text: text = text.replace(">", ">") if "\"" in text: text = text.replace("\"", """) return text except (TypeError, AttributeError): _raise_serialization_error(text) # -------------------------------------------------------------------- def tostring(element, encoding=None, method=None, *, short_empty_elements=True): """Generate string representation of XML element. All subelements are included. If encoding is "unicode", a string is returned. Otherwise a bytestring is returned. *element* is an Element instance, *encoding* is an optional output encoding defaulting to US-ASCII, *method* is an optional output which can be one of "xml" (default), "html", "text" or "c14n". Returns an (optionally) encoded string containing the XML data. """ stream = io.StringIO() if encoding == 'unicode' else io.BytesIO() ElementTree(element).write(stream, encoding, method=method, short_empty_elements=short_empty_elements) return stream.getvalue() class _ListDataStream(io.BufferedIOBase): """An auxiliary stream accumulating into a list reference.""" def __init__(self, lst): self.lst = lst def writable(self): return True def seekable(self): return True def write(self, b): self.lst.append(b) def tell(self): return len(self.lst) def tostringlist(element, encoding=None, method=None, *, short_empty_elements=True): lst = [] stream = _ListDataStream(lst) ElementTree(element).write(stream, encoding, method=method, short_empty_elements=short_empty_elements) return lst def dump(elem): """Write element tree or element structure to sys.stdout. This function should be used for debugging only. *elem* is either an ElementTree, or a single Element. The exact output format is implementation dependent. In this version, it's written as an ordinary XML file. """ # debugging if not isinstance(elem, ElementTree): elem = ElementTree(elem) elem.write(sys.stdout, encoding="unicode") tail = elem.getroot().tail if not tail or tail[-1] != "\n": sys.stdout.write("\n") # -------------------------------------------------------------------- # parsing def parse(source, parser=None): """Parse XML document into element tree. *source* is a filename or file object containing XML data, *parser* is an optional parser instance defaulting to XMLParser. Return an ElementTree instance. """ tree = ElementTree() tree.parse(source, parser) return tree def iterparse(source, events=None, parser=None): """Incrementally parse XML document into ElementTree. This class also reports what's going on to the user based on the *events* it is initialized with. The supported events are the strings "start", "end", "start-ns" and "end-ns" (the "ns" events are used to get detailed namespace information). If *events* is omitted, only "end" events are reported. *source* is a filename or file object containing XML data, *events* is a list of events to report back, *parser* is an optional parser instance. Returns an iterator providing (event, elem) pairs. """ close_source = False if not hasattr(source, "read"): source = open(source, "rb") close_source = True try: return _IterParseIterator(source, events, parser, close_source) except: if close_source: source.close() raise class XMLPullParser: def __init__(self, events=None, *, _parser=None): # The _parser argument is for internal use only and must not be relied # upon in user code. It will be removed in a future release. # See http://bugs.python.org/issue17741 for more details. # _elementtree.c expects a list, not a deque self._events_queue = [] self._index = 0 self._parser = _parser or XMLParser(target=TreeBuilder()) # wire up the parser for event reporting if events is None: events = ("end",) self._parser._setevents(self._events_queue, events) def feed(self, data): """Feed encoded data to parser.""" if self._parser is None: raise ValueError("feed() called after end of stream") if data: try: self._parser.feed(data) except SyntaxError as exc: self._events_queue.append(exc) def _close_and_return_root(self): # iterparse needs this to set its root attribute properly :( root = self._parser.close() self._parser = None return root def close(self): """Finish feeding data to parser. Unlike XMLParser, does not return the root element. Use read_events() to consume elements from XMLPullParser. """ self._close_and_return_root() def read_events(self): """Return an iterator over currently available (event, elem) pairs. Events are consumed from the internal event queue as they are retrieved from the iterator. """ events = self._events_queue while True: index = self._index try: event = events[self._index] # Avoid retaining references to past events events[self._index] = None except IndexError: break index += 1 # Compact the list in a O(1) amortized fashion # As noted above, _elementree.c needs a list, not a deque if index * 2 >= len(events): events[:index] = [] self._index = 0 else: self._index = index if isinstance(event, Exception): raise event else: yield event class _IterParseIterator: def __init__(self, source, events, parser, close_source=False): # Use the internal, undocumented _parser argument for now; When the # parser argument of iterparse is removed, this can be killed. self._parser = XMLPullParser(events=events, _parser=parser) self._file = source self._close_file = close_source self.root = self._root = None def __next__(self): try: while 1: for event in self._parser.read_events(): return event if self._parser._parser is None: break # load event buffer data = self._file.read(16 * 1024) if data: self._parser.feed(data) else: self._root = self._parser._close_and_return_root() self.root = self._root except: if self._close_file: self._file.close() raise if self._close_file: self._file.close() raise StopIteration def __iter__(self): return self def XML(text, parser=None): """Parse XML document from string constant. This function can be used to embed "XML Literals" in Python code. *text* is a string containing XML data, *parser* is an optional parser instance, defaulting to the standard XMLParser. Returns an Element instance. """ if not parser: parser = XMLParser(target=TreeBuilder()) parser.feed(text) return parser.close() def XMLID(text, parser=None): """Parse XML document from string constant for its IDs. *text* is a string containing XML data, *parser* is an optional parser instance, defaulting to the standard XMLParser. Returns an (Element, dict) tuple, in which the dict maps element id:s to elements. """ if not parser: parser = XMLParser(target=TreeBuilder()) parser.feed(text) tree = parser.close() ids = {} for elem in tree.iter(): id = elem.get("id") if id: ids[id] = elem return tree, ids # Parse XML document from string constant. Alias for XML(). fromstring = XML def fromstringlist(sequence, parser=None): """Parse XML document from sequence of string fragments. *sequence* is a list of other sequence, *parser* is an optional parser instance, defaulting to the standard XMLParser. Returns an Element instance. """ if not parser: parser = XMLParser(target=TreeBuilder()) for text in sequence: parser.feed(text) return parser.close() # -------------------------------------------------------------------- class TreeBuilder: """Generic element structure builder. This builder converts a sequence of start, data, and end method calls to a well-formed element structure. You can use this class to build an element structure using a custom XML parser, or a parser for some other XML-like format. *element_factory* is an optional element factory which is called to create new Element instances, as necessary. """ def __init__(self, element_factory=None): self._data = [] # data collector self._elem = [] # element stack self._last = None # last element self._tail = None # true if we're after an end tag if element_factory is None: element_factory = Element self._factory = element_factory def close(self): """Flush builder buffers and return toplevel document Element.""" assert len(self._elem) == 0, "missing end tags" assert self._last is not None, "missing toplevel element" return self._last def _flush(self): if self._data: if self._last is not None: text = "".join(self._data) if self._tail: assert self._last.tail is None, "internal error (tail)" self._last.tail = text else: assert self._last.text is None, "internal error (text)" self._last.text = text self._data = [] def data(self, data): """Add text to current element.""" self._data.append(data) def start(self, tag, attrs): """Open new element and return it. *tag* is the element name, *attrs* is a dict containing element attributes. """ self._flush() self._last = elem = self._factory(tag, attrs) if self._elem: self._elem[-1].append(elem) self._elem.append(elem) self._tail = 0 return elem def end(self, tag): """Close and return current Element. *tag* is the element name. """ self._flush() self._last = self._elem.pop() assert self._last.tag == tag,\ "end tag mismatch (expected %s, got %s)" % ( self._last.tag, tag) self._tail = 1 return self._last # also see ElementTree and TreeBuilder class XMLParser: """Element structure builder for XML source data based on the expat parser. *html* are predefined HTML entities (deprecated and not supported), *target* is an optional target object which defaults to an instance of the standard TreeBuilder class, *encoding* is an optional encoding string which if given, overrides the encoding specified in the XML file: http://www.iana.org/assignments/character-sets """ def __init__(self, html=0, target=None, encoding=None): try: from xml.parsers import expat except ImportError: try: import pyexpat as expat except ImportError: raise ImportError( "No module named expat; use SimpleXMLTreeBuilder instead" ) parser = expat.ParserCreate(encoding, "}") if target is None: target = TreeBuilder() # underscored names are provided for compatibility only self.parser = self._parser = parser self.target = self._target = target self._error = expat.error self._names = {} # name memo cache # main callbacks parser.DefaultHandlerExpand = self._default if hasattr(target, 'start'): parser.StartElementHandler = self._start if hasattr(target, 'end'): parser.EndElementHandler = self._end if hasattr(target, 'data'): parser.CharacterDataHandler = target.data # miscellaneous callbacks if hasattr(target, 'comment'): parser.CommentHandler = target.comment if hasattr(target, 'pi'): parser.ProcessingInstructionHandler = target.pi # Configure pyexpat: buffering, new-style attribute handling. parser.buffer_text = 1 parser.ordered_attributes = 1 parser.specified_attributes = 1 self._doctype = None self.entity = {} try: self.version = "Expat %d.%d.%d" % expat.version_info except AttributeError: pass # unknown def _setevents(self, events_queue, events_to_report): # Internal API for XMLPullParser # events_to_report: a list of events to report during parsing (same as # the *events* of XMLPullParser's constructor. # events_queue: a list of actual parsing events that will be populated # by the underlying parser. # parser = self._parser append = events_queue.append for event_name in events_to_report: if event_name == "start": parser.ordered_attributes = 1 parser.specified_attributes = 1 def handler(tag, attrib_in, event=event_name, append=append, start=self._start): append((event, start(tag, attrib_in))) parser.StartElementHandler = handler elif event_name == "end": def handler(tag, event=event_name, append=append, end=self._end): append((event, end(tag))) parser.EndElementHandler = handler elif event_name == "start-ns": def handler(prefix, uri, event=event_name, append=append): append((event, (prefix or "", uri or ""))) parser.StartNamespaceDeclHandler = handler elif event_name == "end-ns": def handler(prefix, event=event_name, append=append): append((event, None)) parser.EndNamespaceDeclHandler = handler else: raise ValueError("unknown event %r" % event_name) def _raiseerror(self, value): err = ParseError(value) err.code = value.code err.position = value.lineno, value.offset raise err def _fixname(self, key): # expand qname, and convert name string to ascii, if possible try: name = self._names[key] except KeyError: name = key if "}" in name: name = "{" + name self._names[key] = name return name def _start(self, tag, attr_list): # Handler for expat's StartElementHandler. Since ordered_attributes # is set, the attributes are reported as a list of alternating # attribute name,value. fixname = self._fixname tag = fixname(tag) attrib = {} if attr_list: for i in range(0, len(attr_list), 2): attrib[fixname(attr_list[i])] = attr_list[i+1] return self.target.start(tag, attrib) def _end(self, tag): return self.target.end(self._fixname(tag)) def _default(self, text): prefix = text[:1] if prefix == "&": # deal with undefined entities try: data_handler = self.target.data except AttributeError: return try: data_handler(self.entity[text[1:-1]]) except KeyError: from xml.parsers import expat err = expat.error( "undefined entity %s: line %d, column %d" % (text, self.parser.ErrorLineNumber, self.parser.ErrorColumnNumber) ) err.code = 11 # XML_ERROR_UNDEFINED_ENTITY err.lineno = self.parser.ErrorLineNumber err.offset = self.parser.ErrorColumnNumber raise err elif prefix == "<" and text[:9] == "<!DOCTYPE": self._doctype = [] # inside a doctype declaration elif self._doctype is not None: # parse doctype contents if prefix == ">": self._doctype = None return text = text.strip() if not text: return self._doctype.append(text) n = len(self._doctype) if n > 2: type = self._doctype[1] if type == "PUBLIC" and n == 4: name, type, pubid, system = self._doctype if pubid: pubid = pubid[1:-1] elif type == "SYSTEM" and n == 3: name, type, system = self._doctype pubid = None else: return if hasattr(self.target, "doctype"): self.target.doctype(name, pubid, system[1:-1]) elif self.doctype != self._XMLParser__doctype: # warn about deprecated call self._XMLParser__doctype(name, pubid, system[1:-1]) self.doctype(name, pubid, system[1:-1]) self._doctype = None def doctype(self, name, pubid, system): """(Deprecated) Handle doctype declaration *name* is the Doctype name, *pubid* is the public identifier, and *system* is the system identifier. """ warnings.warn( "This method of XMLParser is deprecated. Define doctype() " "method on the TreeBuilder target.", DeprecationWarning, ) # sentinel, if doctype is redefined in a subclass __doctype = doctype def feed(self, data): """Feed encoded data to parser.""" try: self.parser.Parse(data, 0) except self._error as v: self._raiseerror(v) def close(self): """Finish feeding data to parser and return element structure.""" try: self.parser.Parse("", 1) # end of data except self._error as v: self._raiseerror(v) try: close_handler = self.target.close except AttributeError: pass else: return close_handler() finally: # get rid of circular references del self.parser, self._parser del self.target, self._target # Import the C accelerators try: # Element is going to be shadowed by the C implementation. We need to keep # the Python version of it accessible for some "creative" by external code # (see tests) _Element_Py = Element # Element, SubElement, ParseError, TreeBuilder, XMLParser from _elementtree import * except ImportError: pass