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Diffstat (limited to 'slixmpp/xmlstream/tostring.py')
| -rw-r--r-- | slixmpp/xmlstream/tostring.py | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/slixmpp/xmlstream/tostring.py b/slixmpp/xmlstream/tostring.py new file mode 100644 index 00000000..6726bf1e --- /dev/null +++ b/slixmpp/xmlstream/tostring.py @@ -0,0 +1,183 @@ +# -*- coding: utf-8 -*- +""" + slixmpp.xmlstream.tostring + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + + This module converts XML objects into Unicode strings and + intelligently includes namespaces only when necessary to + keep the output readable. + + Part of Slixmpp: The Slick XMPP Library + + :copyright: (c) 2011 Nathanael C. Fritz + :license: MIT, see LICENSE for more details +""" + +XML_NS = 'http://www.w3.org/XML/1998/namespace' + + +def tostring(xml=None, xmlns='', stream=None, outbuffer='', + top_level=False, open_only=False, namespaces=None): + """Serialize an XML object to a Unicode string. + + If an outer xmlns is provided using ``xmlns``, then the current element's + namespace will not be included if it matches the outer namespace. An + exception is made for elements that have an attached stream, and appear + at the stream root. + + :param XML xml: The XML object to serialize. + :param string xmlns: Optional namespace of an element wrapping the XML + object. + :param stream: The XML stream that generated the XML object. + :param string outbuffer: Optional buffer for storing serializations + during recursive calls. + :param bool top_level: Indicates that the element is the outermost + element. + :param set namespaces: Track which namespaces are in active use so + that new ones can be declared when needed. + + :type xml: :py:class:`~xml.etree.ElementTree.Element` + :type stream: :class:`~slixmpp.xmlstream.xmlstream.XMLStream` + + :rtype: Unicode string + """ + # Add previous results to the start of the output. + output = [outbuffer] + + # Extract the element's tag name. + tag_name = xml.tag.split('}', 1)[-1] + + # Extract the element's namespace if it is defined. + if '}' in xml.tag: + tag_xmlns = xml.tag.split('}', 1)[0][1:] + else: + tag_xmlns = '' + + default_ns = '' + stream_ns = '' + use_cdata = False + + if stream: + default_ns = stream.default_ns + stream_ns = stream.stream_ns + use_cdata = stream.use_cdata + + # Output the tag name and derived namespace of the element. + namespace = '' + if tag_xmlns: + if top_level and tag_xmlns not in [default_ns, xmlns, stream_ns] \ + or not top_level and tag_xmlns != xmlns: + namespace = ' xmlns="%s"' % tag_xmlns + if stream and tag_xmlns in stream.namespace_map: + mapped_namespace = stream.namespace_map[tag_xmlns] + if mapped_namespace: + tag_name = "%s:%s" % (mapped_namespace, tag_name) + output.append("<%s" % tag_name) + output.append(namespace) + + # Output escaped attribute values. + new_namespaces = set() + for attrib, value in xml.attrib.items(): + value = escape(value, use_cdata) + if '}' not in attrib: + output.append(' %s="%s"' % (attrib, value)) + else: + attrib_ns = attrib.split('}')[0][1:] + attrib = attrib.split('}')[1] + if attrib_ns == XML_NS: + output.append(' xml:%s="%s"' % (attrib, value)) + elif stream and attrib_ns in stream.namespace_map: + mapped_ns = stream.namespace_map[attrib_ns] + if mapped_ns: + if namespaces is None: + namespaces = set() + if attrib_ns not in namespaces: + namespaces.add(attrib_ns) + new_namespaces.add(attrib_ns) + output.append(' xmlns:%s="%s"' % ( + mapped_ns, attrib_ns)) + output.append(' %s:%s="%s"' % ( + mapped_ns, attrib, value)) + + if open_only: + # Only output the opening tag, regardless of content. + output.append(">") + return ''.join(output) + + if len(xml) or xml.text: + # If there are additional child elements to serialize. + output.append(">") + if xml.text: + output.append(escape(xml.text, use_cdata)) + if len(xml): + for child in xml: + output.append(tostring(child, tag_xmlns, stream, + namespaces=namespaces)) + output.append("</%s>" % tag_name) + elif xml.text: + # If we only have text content. + output.append(">%s</%s>" % (escape(xml.text, use_cdata), tag_name)) + else: + # Empty element. + output.append(" />") + if xml.tail: + # If there is additional text after the element. + output.append(escape(xml.tail, use_cdata)) + for ns in new_namespaces: + # Remove namespaces introduced in this context. This is necessary + # because the namespaces object continues to be shared with other + # contexts. + namespaces.remove(ns) + return ''.join(output) + + +def escape(text, use_cdata=False): + """Convert special characters in XML to escape sequences. + + :param string text: The XML text to convert. + :rtype: Unicode string + """ + escapes = {'&': '&', + '<': '<', + '>': '>', + "'": ''', + '"': '"'} + + if not use_cdata: + text = list(text) + for i, c in enumerate(text): + text[i] = escapes.get(c, c) + return ''.join(text) + else: + escape_needed = False + for c in text: + if c in escapes: + escape_needed = True + break + if escape_needed: + escaped = map(lambda x : "<![CDATA[%s]]>" % x, text.split("]]>")) + return "<![CDATA[]]]><![CDATA[]>]]>".join(escaped) + return text + + +def _get_highlight(): + try: + from pygments import highlight + from pygments.lexers import get_lexer_by_name + from pygments.formatters import Terminal256Formatter + + LEXER = get_lexer_by_name('xml') + FORMATTER = Terminal256Formatter() + + class Highlighter: + __slots__ = ['string'] + def __init__(self, string): + self.string = string + def __str__(self): + return highlight(str(self.string), LEXER, FORMATTER).strip() + + return Highlighter + except ImportError: + return lambda x: x + +highlight = _get_highlight() |