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"""Shim module exporting the same ElementTree API for lxml and
xml.etree backends.
When lxml is installed, it is automatically preferred over the built-in
xml.etree module.
On Python 2.7, the cElementTree module is preferred over the pure-python
ElementTree module.
Besides exporting a unified interface, this also defines extra functions
or subclasses built-in ElementTree classes to add features that are
only availble in lxml, like OrderedDict for attributes, pretty_print and
iterwalk.
"""
from fontTools.misc.textTools import tostr
XML_DECLARATION = """<?xml version='1.0' encoding='%s'?>"""
__all__ = [
# public symbols
"Comment",
"dump",
"Element",
"ElementTree",
"fromstring",
"fromstringlist",
"iselement",
"iterparse",
"parse",
"ParseError",
"PI",
"ProcessingInstruction",
"QName",
"SubElement",
"tostring",
"tostringlist",
"TreeBuilder",
"XML",
"XMLParser",
"register_namespace",
]
try:
from lxml.etree import *
_have_lxml = True
except ImportError:
try:
from xml.etree.cElementTree import *
# the cElementTree version of XML function doesn't support
# the optional 'parser' keyword argument
from xml.etree.ElementTree import XML
except ImportError: # pragma: no cover
from xml.etree.ElementTree import *
_have_lxml = False
import sys
# dict is always ordered in python >= 3.6 and on pypy
PY36 = sys.version_info >= (3, 6)
try:
import __pypy__
except ImportError:
__pypy__ = None
_dict_is_ordered = bool(PY36 or __pypy__)
del PY36, __pypy__
if _dict_is_ordered:
_Attrib = dict
else:
from collections import OrderedDict as _Attrib
if isinstance(Element, type):
_Element = Element
else:
# in py27, cElementTree.Element cannot be subclassed, so
# we need to import the pure-python class
from xml.etree.ElementTree import Element as _Element
class Element(_Element):
"""Element subclass that keeps the order of attributes."""
def __init__(self, tag, attrib=_Attrib(), **extra):
super(Element, self).__init__(tag)
self.attrib = _Attrib()
if attrib:
self.attrib.update(attrib)
if extra:
self.attrib.update(extra)
def SubElement(parent, tag, attrib=_Attrib(), **extra):
"""Must override SubElement as well otherwise _elementtree.SubElement
fails if 'parent' is a subclass of Element object.
"""
element = parent.__class__(tag, attrib, **extra)
parent.append(element)
return element
def _iterwalk(element, events, tag):
include = tag is None or element.tag == tag
if include and "start" in events:
yield ("start", element)
for e in element:
for item in _iterwalk(e, events, tag):
yield item
if include:
yield ("end", element)
def iterwalk(element_or_tree, events=("end",), tag=None):
"""A tree walker that generates events from an existing tree as
if it was parsing XML data with iterparse().
Drop-in replacement for lxml.etree.iterwalk.
"""
if iselement(element_or_tree):
element = element_or_tree
else:
element = element_or_tree.getroot()
if tag == "*":
tag = None
for item in _iterwalk(element, events, tag):
yield item
_ElementTree = ElementTree
class ElementTree(_ElementTree):
"""ElementTree subclass that adds 'pretty_print' and 'doctype'
arguments to the 'write' method.
Currently these are only supported for the default XML serialization
'method', and not also for "html" or "text", for these are delegated
to the base class.
"""
def write(
self,
file_or_filename,
encoding=None,
xml_declaration=False,
method=None,
doctype=None,
pretty_print=False,
):
if method and method != "xml":
# delegate to super-class
super(ElementTree, self).write(
file_or_filename,
encoding=encoding,
xml_declaration=xml_declaration,
method=method,
)
return
if encoding is not None and encoding.lower() == "unicode":
if xml_declaration:
raise ValueError(
"Serialisation to unicode must not request an XML declaration"
)
write_declaration = False
encoding = "unicode"
elif xml_declaration is None:
# by default, write an XML declaration only for non-standard encodings
write_declaration = encoding is not None and encoding.upper() not in (
"ASCII",
"UTF-8",
"UTF8",
"US-ASCII",
)
else:
write_declaration = xml_declaration
if encoding is None:
encoding = "ASCII"
if pretty_print:
# NOTE this will modify the tree in-place
_indent(self._root)
with _get_writer(file_or_filename, encoding) as write:
if write_declaration:
write(XML_DECLARATION % encoding.upper())
if pretty_print:
write("\n")
if doctype:
write(_tounicode(doctype))
if pretty_print:
write("\n")
qnames, namespaces = _namespaces(self._root)
_serialize_xml(write, self._root, qnames, namespaces)
import io
def tostring(
element,
encoding=None,
xml_declaration=None,
method=None,
doctype=None,
pretty_print=False,
):
"""Custom 'tostring' function that uses our ElementTree subclass, with
pretty_print support.
"""
stream = io.StringIO() if encoding == "unicode" else io.BytesIO()
ElementTree(element).write(
stream,
encoding=encoding,
xml_declaration=xml_declaration,
method=method,
doctype=doctype,
pretty_print=pretty_print,
)
return stream.getvalue()
# serialization support
import re
# Valid XML strings can include any Unicode character, excluding control
# characters, the surrogate blocks, FFFE, and FFFF:
# Char ::= #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
# Here we reversed the pattern to match only the invalid characters.
# For the 'narrow' python builds supporting only UCS-2, which represent
# characters beyond BMP as UTF-16 surrogate pairs, we need to pass through
# the surrogate block. I haven't found a more elegant solution...
UCS2 = sys.maxunicode < 0x10FFFF
if UCS2:
_invalid_xml_string = re.compile(
"[\u0000-\u0008\u000B-\u000C\u000E-\u001F\uFFFE-\uFFFF]"
)
else:
_invalid_xml_string = re.compile(
"[\u0000-\u0008\u000B-\u000C\u000E-\u001F\uD800-\uDFFF\uFFFE-\uFFFF]"
)
def _tounicode(s):
"""Test if a string is valid user input and decode it to unicode string
using ASCII encoding if it's a bytes string.
Reject all bytes/unicode input that contains non-XML characters.
Reject all bytes input that contains non-ASCII characters.
"""
try:
s = tostr(s, encoding="ascii", errors="strict")
except UnicodeDecodeError:
raise ValueError(
"Bytes strings can only contain ASCII characters. "
"Use unicode strings for non-ASCII characters."
)
except AttributeError:
_raise_serialization_error(s)
if s and _invalid_xml_string.search(s):
raise ValueError(
"All strings must be XML compatible: Unicode or ASCII, "
"no NULL bytes or control characters"
)
return s
import contextlib
@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
f = open(
file_or_filename,
"w",
encoding="utf-8" if encoding == "unicode" else encoding,
errors="xmlcharrefreplace",
)
with f:
yield f.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
detach_buffer = False
if isinstance(file_or_filename, io.BufferedIOBase):
buf = file_or_filename
elif isinstance(file_or_filename, io.RawIOBase):
buf = io.BufferedWriter(file_or_filename)
detach_buffer = True
else:
# This is to handle passed objects that aren't in the
# IOBase hierarchy, but just have a write method
buf = io.BufferedIOBase()
buf.writable = lambda: True
buf.write = write
try:
# TextIOWrapper uses this methods to determine
# if BOM (for UTF-16, etc) should be added
buf.seekable = file_or_filename.seekable
buf.tell = file_or_filename.tell
except AttributeError:
pass
wrapper = io.TextIOWrapper(
buf,
encoding=encoding,
errors="xmlcharrefreplace",
newline="\n",
)
try:
yield wrapper.write
finally:
# Keep the original file open when the TextIOWrapper and
# the BufferedWriter are destroyed
wrapper.detach()
if detach_buffer:
buf.detach()
from xml.etree.ElementTree import _namespace_map
def _namespaces(elem):
# identify namespaces used in this tree
# maps qnames to *encoded* prefix:local names
qnames = {None: None}
# maps uri:s to prefixes
namespaces = {}
def add_qname(qname):
# calculate serialized qname representation
try:
qname = _tounicode(qname)
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)
else:
prefix = _tounicode(prefix)
if prefix != "xml":
namespaces[uri] = prefix
if prefix:
qnames[qname] = "%s:%s" % (prefix, tag)
else:
qnames[qname] = tag # default element
else:
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, **kwargs):
tag = elem.tag
text = elem.text
if tag is Comment:
write("<!--%s-->" % _tounicode(text))
elif tag is ProcessingInstruction:
write("<?%s?>" % _tounicode(text))
else:
tag = qnames[_tounicode(tag) if tag is not None else None]
if tag is None:
if text:
write(_escape_cdata(text))
for e in elem:
_serialize_xml(write, e, qnames, None)
else:
write("<" + tag)
if namespaces:
for uri, prefix in sorted(
namespaces.items(), key=lambda x: x[1]
): # sort on prefix
if prefix:
prefix = ":" + prefix
write(' xmlns%s="%s"' % (prefix, _escape_attrib(uri)))
attrs = elem.attrib
if attrs:
# try to keep existing attrib order
if len(attrs) <= 1 or type(attrs) is _Attrib:
items = attrs.items()
else:
# if plain dict, use lexical order
items = sorted(attrs.items())
for k, v in items:
if isinstance(k, QName):
k = _tounicode(k.text)
else:
k = _tounicode(k)
if isinstance(v, QName):
v = qnames[_tounicode(v.text)]
else:
v = _escape_attrib(v)
write(' %s="%s"' % (qnames[k], v))
if text is not None or len(elem):
write(">")
if text:
write(_escape_cdata(text))
for e in elem:
_serialize_xml(write, e, qnames, None)
write("</" + tag + ">")
else:
write("/>")
if elem.tail:
write(_escape_cdata(elem.tail))
def _raise_serialization_error(text):
raise TypeError("cannot serialize %r (type %s)" % (text, type(text).__name__))
def _escape_cdata(text):
# escape character data
try:
text = _tounicode(text)
# it's worth avoiding do-nothing calls for short strings
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:
text = _tounicode(text)
if "&" in text:
text = text.replace("&", "&")
if "<" in text:
text = text.replace("<", "<")
if ">" in text:
text = text.replace(">", ">")
if '"' in text:
text = text.replace('"', """)
if "\n" in text:
text = text.replace("\n", " ")
return text
except (TypeError, AttributeError):
_raise_serialization_error(text)
def _indent(elem, level=0):
# From http://effbot.org/zone/element-lib.htm#prettyprint
i = "\n" + level * " "
if len(elem):
if not elem.text or not elem.text.strip():
elem.text = i + " "
if not elem.tail or not elem.tail.strip():
elem.tail = i
for elem in elem:
_indent(elem, level + 1)
if not elem.tail or not elem.tail.strip():
elem.tail = i
else:
if level and (not elem.tail or not elem.tail.strip()):
elem.tail = i
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