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# -*- coding: UTF-8 -*-
# Copyright 2014 Red Hat, Inc.
# Part of clufter project
# Licensed under GPLv2+ (a copy included | http://gnu.org/licenses/gpl-2.0.txt)
"""XML helpers"""
__author__ = "Jan Pokorný <jpokorny @at@ Red Hat .dot. com>"
from copy import deepcopy
from lxml import etree
from .error import ClufterPlainError
from .utils import selfaware
NAMESPACES = {
'clufter': 'http://people.redhat.com/jpokorny/ns/clufter',
'rng': 'http://relaxng.org/ns/structure/1.0',
'xsl': 'http://www.w3.org/1999/XSL/Transform',
}
xslt_identity = '''\
<xsl:template match="{0}@*|{0}node()"
xmlns:xsl="''' + NAMESPACES['xsl'] + '''">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>'''
class UtilsXmlError(ClufterPlainError):
pass
def squote(s):
"""Simple quote"""
return "'" + s + "'"
def namespaced(ns, ident):
"""Return `ident` in Clark's notation denoting `ns` namespace"""
ret = "{{{0}}}{1}".format(NAMESPACES.get(ns, ns), ident)
return ret
def nselem(ns, tag, **kwargs):
return etree.Element(namespaced(ns, tag), **kwargs)
rng_get_start = etree.ETXPath("/{0}/{1}"
.format(namespaced('rng', 'grammar'),
namespaced('rng', 'start')))
xml_get_root_pi = etree.XPath("/*/processing-instruction()")
xmltag_get_localname = lambda tag: etree.QName(tag).localname
xmltag_get_namespace = lambda tag: etree.QName(tag).namespace
RNG_ELEMENT = ("/{0}//{1}".format(namespaced('rng', 'grammar'),
namespaced('rng', 'element'))
.replace('{', '{{').replace('}', '}}')
+ "[@name = '{0}']")
class ElementJuggler(object):
"""Element juggling, possibly utilizing own temporary holder
This can be handy e.g. to automatically strip unused namespaces
for `tostring` method, without a need to copy/reparse, followed
by returning the element back.
"""
_aside_tree = etree.ElementTree(etree.Element('ROOT'))
def __init__(self, tree=_aside_tree):
self._root = tree.getroot()
def grab(self, elem):
parent = elem.getparent()
assert parent is not self._root
parent_index = parent.index(elem)
self._root.append(elem)
return parent, parent_index
@staticmethod
def rebind(elem, parent_pos):
parent, parent_index = parent_pos
parent.insert(parent_index, elem)
return elem
def drop(self, elem):
parent = elem.getparent()
if parent is not self._root:
raise ValueError
parent.remove(elem)
element_juggler = ElementJuggler()
@selfaware
def rng_pivot(me, et, tag):
"""Given Relax NG grammar etree as `et`, change start tag (in situ!)
Use copy.deepcopy or so to (somewhat) preserve the original.
Returns the live reference to the target element, i.e.,
at_start = rng_pivot(et, tag)
is equivalent to
rng_pivot(et, tag)
at_start = rng_get_start(et)[0]
"""
start = rng_get_start(et)
localname = xmltag_get_localname(tag)
if len(start) != 1:
raise UtilsXmlError("Cannot change start if grammar's `start' is"
" not contained exactly once ({0} times)"
.format(len(start)))
target = etree.ETXPath(RNG_ELEMENT.format(tag))(et)
if len(target) != 1:
raise UtilsXmlError("Cannot change start if the start element `{0}'"
" is not contained exactly once ({1} times)"
.format(localname, len(target)))
start, target = start[0], target[0]
parent_start, parent_target = start.getparent(), target.getparent()
index_target = parent_target.index(target)
label = me.__name__ + '_' + localname
# target's content place directly under /grammar wrapped with new define...
new_define = nselem('rng', 'define', name=label)
new_define.append(target)
parent_start.append(new_define)
# ... while the original occurrence substituted in-situ with the reference
new_ref = nselem('rng', 'ref', name=label)
parent_target.insert(index_target, new_ref)
# ... and finally /grammar/start pointed anew to refer to the new label
start_ref = nselem('rng', 'ref', name=label)
start.clear()
start.append(start_ref)
return target
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