/
serializers.py
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/
serializers.py
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# Add x/html serialization to `Elementree`
# Taken from ElementTree 1.3 preview with slight modifications
#
# Copyright (c) 1999-2007 by Fredrik Lundh. All rights reserved.
#
# fredrik@pythonware.com
# https://www.pythonware.com/
#
# --------------------------------------------------------------------
# The ElementTree toolkit is
#
# Copyright (c) 1999-2007 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.
# --------------------------------------------------------------------
from xml.etree.ElementTree import ProcessingInstruction
from xml.etree.ElementTree import Comment, ElementTree, QName
import re
__all__ = ['to_html_string', 'to_xhtml_string']
HTML_EMPTY = ("area", "base", "basefont", "br", "col", "frame", "hr",
"img", "input", "isindex", "link", "meta", "param")
RE_AMP = re.compile(r'&(?!(?:\#[0-9]+|\#x[0-9a-f]+|[0-9a-z]+);)', re.I)
try:
HTML_EMPTY = set(HTML_EMPTY)
except NameError: # pragma: no cover
pass
def _raise_serialization_error(text): # pragma: no cover
raise TypeError(
"cannot serialize {!r} (type {})".format(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:
# Only replace & when not part of an entity
text = RE_AMP.sub('&', text)
if "<" in text:
text = text.replace("<", "<")
if ">" in text:
text = text.replace(">", ">")
return text
except (TypeError, AttributeError): # pragma: no cover
_raise_serialization_error(text)
def _escape_attrib(text):
# escape attribute value
try:
if "&" in text:
# Only replace & when not part of an entity
text = RE_AMP.sub('&', text)
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): # pragma: no cover
_raise_serialization_error(text)
def _escape_attrib_html(text):
# escape attribute value
try:
if "&" in text:
# Only replace & when not part of an entity
text = RE_AMP.sub('&', text)
if "<" in text:
text = text.replace("<", "<")
if ">" in text:
text = text.replace(">", ">")
if "\"" in text:
text = text.replace("\"", """)
return text
except (TypeError, AttributeError): # pragma: no cover
_raise_serialization_error(text)
def _serialize_html(write, elem, format):
tag = elem.tag
text = elem.text
if tag is Comment:
write("<!--%s-->" % _escape_cdata(text))
elif tag is ProcessingInstruction:
write("<?%s?>" % _escape_cdata(text))
elif tag is None:
if text:
write(_escape_cdata(text))
for e in elem:
_serialize_html(write, e, format)
else:
namespace_uri = None
if isinstance(tag, QName):
# `QNAME` objects store their data as a string: `{uri}tag`
if tag.text[:1] == "{":
namespace_uri, tag = tag.text[1:].split("}", 1)
else:
raise ValueError('QName objects must define a tag.')
write("<" + tag)
items = elem.items()
if items:
items = sorted(items) # lexical order
for k, v in items:
if isinstance(k, QName):
# Assume a text only `QName`
k = k.text
if isinstance(v, QName):
# Assume a text only `QName`
v = v.text
else:
v = _escape_attrib_html(v)
if k == v and format == 'html':
# handle boolean attributes
write(" %s" % v)
else:
write(' {}="{}"'.format(k, v))
if namespace_uri:
write(' xmlns="%s"' % (_escape_attrib(namespace_uri)))
if format == "xhtml" and tag.lower() in HTML_EMPTY:
write(" />")
else:
write(">")
if text:
if tag.lower() in ["script", "style"]:
write(text)
else:
write(_escape_cdata(text))
for e in elem:
_serialize_html(write, e, format)
if tag.lower() not in HTML_EMPTY:
write("</" + tag + ">")
if elem.tail:
write(_escape_cdata(elem.tail))
def _write_html(root, format="html"):
assert root is not None
data = []
write = data.append
_serialize_html(write, root, format)
return "".join(data)
# --------------------------------------------------------------------
# public functions
def to_html_string(element):
return _write_html(ElementTree(element).getroot(), format="html")
def to_xhtml_string(element):
return _write_html(ElementTree(element).getroot(), format="xhtml")