Integrated my history into data
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Karthik Pullela
@@ -0,0 +1,318 @@
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# -*- test-case-name: yadis.test.test_etxrd -*-
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"""
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ElementTree interface to an XRD document.
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"""
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__all__ = [
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'nsTag',
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'mkXRDTag',
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'isXRDS',
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'parseXRDS',
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'getCanonicalID',
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'getYadisXRD',
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'getPriorityStrict',
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'getPriority',
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'prioSort',
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'iterServices',
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'expandService',
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'expandServices',
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]
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import sys
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import random
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import functools
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from datetime import datetime
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from time import strptime
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from openid.oidutil import importElementTree, importSafeElementTree
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ElementTree = importElementTree()
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SafeElementTree = importSafeElementTree()
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from openid.yadis import xri
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class XRDSError(Exception):
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"""An error with the XRDS document."""
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# The exception that triggered this exception
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reason = None
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class XRDSFraud(XRDSError):
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"""Raised when there's an assertion in the XRDS that it does not have
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the authority to make.
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"""
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def parseXRDS(text):
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"""Parse the given text as an XRDS document.
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@return: ElementTree containing an XRDS document
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@raises XRDSError: When there is a parse error or the document does
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not contain an XRDS.
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"""
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try:
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# lxml prefers to parse bytestrings, and occasionally chokes on a
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# combination of text strings and declared XML encodings -- see
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# https://github.com/necaris/python3-openid/issues/19
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# To avoid this, we ensure that the 'text' we're parsing is actually
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# a bytestring
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bytestring = text.encode('utf8') if isinstance(text, str) else text
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element = SafeElementTree.XML(bytestring)
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except (SystemExit, MemoryError, AssertionError, ImportError):
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raise
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except Exception as why:
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exc = XRDSError('Error parsing document as XML')
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exc.reason = why
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raise exc
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else:
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tree = ElementTree.ElementTree(element)
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if not isXRDS(tree):
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raise XRDSError('Not an XRDS document')
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return tree
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XRD_NS_2_0 = 'xri://$xrd*($v*2.0)'
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XRDS_NS = 'xri://$xrds'
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def nsTag(ns, t):
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return '{%s}%s' % (ns, t)
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def mkXRDTag(t):
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"""basestring -> basestring
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Create a tag name in the XRD 2.0 XML namespace suitable for using
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with ElementTree
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"""
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return nsTag(XRD_NS_2_0, t)
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def mkXRDSTag(t):
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"""basestring -> basestring
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Create a tag name in the XRDS XML namespace suitable for using
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with ElementTree
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"""
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return nsTag(XRDS_NS, t)
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# Tags that are used in Yadis documents
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root_tag = mkXRDSTag('XRDS')
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service_tag = mkXRDTag('Service')
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xrd_tag = mkXRDTag('XRD')
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type_tag = mkXRDTag('Type')
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uri_tag = mkXRDTag('URI')
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expires_tag = mkXRDTag('Expires')
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# Other XRD tags
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canonicalID_tag = mkXRDTag('CanonicalID')
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def isXRDS(xrd_tree):
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"""Is this document an XRDS document?"""
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root = xrd_tree.getroot()
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return root.tag == root_tag
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def getYadisXRD(xrd_tree):
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"""Return the XRD element that should contain the Yadis services"""
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xrd = None
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# for the side-effect of assigning the last one in the list to the
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# xrd variable
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for xrd in xrd_tree.findall(xrd_tag):
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pass
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# There were no elements found, or else xrd would be set to the
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# last one
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if xrd is None:
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raise XRDSError('No XRD present in tree')
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return xrd
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def getXRDExpiration(xrd_element, default=None):
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"""Return the expiration date of this XRD element, or None if no
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expiration was specified.
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@type xrd_element: ElementTree node
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@param default: The value to use as the expiration if no
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expiration was specified in the XRD.
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@rtype: datetime.datetime
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@raises ValueError: If the xrd:Expires element is present, but its
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contents are not formatted according to the specification.
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"""
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expires_element = xrd_element.find(expires_tag)
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if expires_element is None:
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return default
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else:
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expires_string = expires_element.text
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# Will raise ValueError if the string is not the expected format
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expires_time = strptime(expires_string, "%Y-%m-%dT%H:%M:%SZ")
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return datetime(*expires_time[0:6])
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def getCanonicalID(iname, xrd_tree):
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"""Return the CanonicalID from this XRDS document.
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@param iname: the XRI being resolved.
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@type iname: unicode
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@param xrd_tree: The XRDS output from the resolver.
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@type xrd_tree: ElementTree
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@returns: The XRI CanonicalID or None.
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@returntype: unicode or None
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"""
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xrd_list = xrd_tree.findall(xrd_tag)
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xrd_list.reverse()
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try:
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canonicalID = xri.XRI(xrd_list[0].findall(canonicalID_tag)[0].text)
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except IndexError:
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return None
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childID = canonicalID.lower()
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for xrd in xrd_list[1:]:
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parent_sought = childID.rsplit("!", 1)[0]
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parent = xri.XRI(xrd.findtext(canonicalID_tag))
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if parent_sought != parent.lower():
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raise XRDSFraud("%r can not come from %s" % (childID, parent))
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childID = parent_sought
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root = xri.rootAuthority(iname)
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if not xri.providerIsAuthoritative(root, childID):
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raise XRDSFraud("%r can not come from root %r" % (childID, root))
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return canonicalID
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@functools.total_ordering
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class _Max(object):
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"""
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Value that compares greater than any other value.
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Should only be used as a singleton. Implemented for use as a
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priority value for when a priority is not specified.
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"""
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def __lt__(self, other):
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return isinstance(other, self.__class__)
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def __eq__(self, other):
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return isinstance(other, self.__class__)
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Max = _Max()
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def getPriorityStrict(element):
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"""Get the priority of this element.
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Raises ValueError if the value of the priority is invalid. If no
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priority is specified, it returns a value that compares greater
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than any other value.
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"""
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prio_str = element.get('priority')
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if prio_str is not None:
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prio_val = int(prio_str)
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if prio_val >= 0:
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return prio_val
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else:
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raise ValueError('Priority values must be non-negative integers')
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# Any errors in parsing the priority fall through to here
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return Max
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def getPriority(element):
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"""Get the priority of this element
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Returns Max if no priority is specified or the priority value is invalid.
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"""
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try:
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return getPriorityStrict(element)
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except ValueError:
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return Max
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def prioSort(elements):
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"""Sort a list of elements that have priority attributes"""
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# Randomize the services before sorting so that equal priority
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# elements are load-balanced.
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random.shuffle(elements)
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sorted_elems = sorted(elements, key=getPriority)
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return sorted_elems
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def iterServices(xrd_tree):
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"""Return an iterable over the Service elements in the Yadis XRD
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sorted by priority"""
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xrd = getYadisXRD(xrd_tree)
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return prioSort(xrd.findall(service_tag))
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def sortedURIs(service_element):
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"""Given a Service element, return a list of the contents of all
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URI tags in priority order."""
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return [
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uri_element.text
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for uri_element in prioSort(service_element.findall(uri_tag))
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]
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def getTypeURIs(service_element):
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"""Given a Service element, return a list of the contents of all
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Type tags"""
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return [
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type_element.text for type_element in service_element.findall(type_tag)
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]
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def expandService(service_element):
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"""Take a service element and expand it into an iterator of:
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([type_uri], uri, service_element)
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"""
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uris = sortedURIs(service_element)
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if not uris:
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uris = [None]
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expanded = []
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for uri in uris:
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type_uris = getTypeURIs(service_element)
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expanded.append((type_uris, uri, service_element))
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return expanded
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def expandServices(service_elements):
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"""Take a sorted iterator of service elements and expand it into a
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sorted iterator of:
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([type_uri], uri, service_element)
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There may be more than one item in the resulting list for each
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service element if there is more than one URI or type for a
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service, but each triple will be unique.
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If there is no URI or Type for a Service element, it will not
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appear in the result.
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"""
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expanded = []
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for service_element in service_elements:
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expanded.extend(expandService(service_element))
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return expanded
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