Lib/xml/etree/ElementPath.py - platform/external/python/cpython3 - Gitiles

 #
 # ElementTree
 # $Id: ElementPath.py 3375 2008-02-13 08:05:08Z fredrik $
 #
 # limited xpath support for element trees
 #
 # history:
 # 2003-05-23 fl   created
 # 2003-05-28 fl   added support for // etc
 # 2003-08-27 fl   fixed parsing of periods in element names
 # 2007-09-10 fl   new selection engine
 # 2007-09-12 fl   fixed parent selector
 # 2007-09-13 fl   added iterfind; changed findall to return a list
 # 2007-11-30 fl   added namespaces support
 # 2009-10-30 fl   added child element value filter
 #
 # Copyright (c) 2003-2009 by Fredrik Lundh.  All rights reserved.
 #
 # fredrik@pythonware.com
 # http://www.pythonware.com
 #
 # --------------------------------------------------------------------
 # The ElementTree toolkit is
 #
 # Copyright (c) 1999-2009 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.
 # --------------------------------------------------------------------

 # Licensed to PSF under a Contributor Agreement.
 # See http://www.python.org/psf/license for licensing details.

 ##
 # Implementation module for XPath support.  There's usually no reason
 # to import this module directly; the <b>ElementTree</b> does this for
 # you, if needed.
 ##

 import re

 xpath_tokenizer_re = re.compile(
     "("
     "'[^']*'|\"[^\"]*\"|"
     "::|"
     "//?|"
     "\.\.|"
     "\(\)|"
     "[/.*:\[\]\(\)@=])|"
     "((?:\{[^}]+\})?[^/\[\]\(\)@=\s]+)|"
     "\s+"
     )

 def xpath_tokenizer(pattern, namespaces=None):
     for token in xpath_tokenizer_re.findall(pattern):
         tag = token[1]
         if tag and tag[0] != "{" and ":" in tag:
             try:
                 prefix, uri = tag.split(":", 1)
                 if not namespaces:
                     raise KeyError
                 yield token[0], "{%s}%s" % (namespaces[prefix], uri)
             except KeyError:
                 raise SyntaxError("prefix %r not found in prefix map" % prefix)
         else:
             yield token

 def get_parent_map(context):
     parent_map = context.parent_map
     if parent_map is None:
         context.parent_map = parent_map = {}
         for p in context.root.iter():
             for e in p:
                 parent_map[e] = p
     return parent_map

 def prepare_child(next, token):
     tag = token[1]
     def select(context, result):
         for elem in result:
             for e in elem:
                 if e.tag == tag:
                     yield e
     return select

 def prepare_star(next, token):
     def select(context, result):
         for elem in result:
             yield from elem
     return select

 def prepare_self(next, token):
     def select(context, result):
         yield from result
     return select

 def prepare_descendant(next, token):
     try:
         token = next()
     except StopIteration:
         return
     if token[0] == "*":
         tag = "*"
     elif not token[0]:
         tag = token[1]
     else:
         raise SyntaxError("invalid descendant")
     def select(context, result):
         for elem in result:
             for e in elem.iter(tag):
                 if e is not elem:
                     yield e
     return select

 def prepare_parent(next, token):
     def select(context, result):
         # FIXME: raise error if .. is applied at toplevel?
         parent_map = get_parent_map(context)
         result_map = {}
         for elem in result:
             if elem in parent_map:
                 parent = parent_map[elem]
                 if parent not in result_map:
                     result_map[parent] = None
                     yield parent
     return select

 def prepare_predicate(next, token):
     # FIXME: replace with real parser!!! refs:
     # http://effbot.org/zone/simple-iterator-parser.htm
     # http://javascript.crockford.com/tdop/tdop.html
     signature = []
     predicate = []
     while 1:
         try:
             token = next()
         except StopIteration:
             return
         if token[0] == "]":
             break
         if token[0] and token[0][:1] in "'\"":
             token = "'", token[0][1:-1]
         signature.append(token[0] or "-")
         predicate.append(token[1])
     signature = "".join(signature)
     # use signature to determine predicate type
     if signature == "@-":
         # [@attribute] predicate
         key = predicate[1]
         def select(context, result):
             for elem in result:
                 if elem.get(key) is not None:
                     yield elem
         return select
     if signature == "@-='":
         # [@attribute='value']
         key = predicate[1]
         value = predicate[-1]
         def select(context, result):
             for elem in result:
                 if elem.get(key) == value:
                     yield elem
         return select
     if signature == "-" and not re.match("\-?\d+$", predicate[0]):
         # [tag]
         tag = predicate[0]
         def select(context, result):
             for elem in result:
                 if elem.find(tag) is not None:
                     yield elem
         return select
     if signature == "-='" and not re.match("\-?\d+$", predicate[0]):
         # [tag='value']
         tag = predicate[0]
         value = predicate[-1]
         def select(context, result):
             for elem in result:
                 for e in elem.findall(tag):
                     if "".join(e.itertext()) == value:
                         yield elem
                         break
         return select
     if signature == "-" or signature == "-()" or signature == "-()-":
         # [index] or [last()] or [last()-index]
         if signature == "-":
             # [index]
             index = int(predicate[0]) - 1
             if index < 0:
                 raise SyntaxError("XPath position >= 1 expected")
         else:
             if predicate[0] != "last":
                 raise SyntaxError("unsupported function")
             if signature == "-()-":
                 try:
                     index = int(predicate[2]) - 1
                 except ValueError:
                     raise SyntaxError("unsupported expression")
                 if index > -2:
                     raise SyntaxError("XPath offset from last() must be negative")
             else:
                 index = -1
         def select(context, result):
             parent_map = get_parent_map(context)
             for elem in result:
                 try:
                     parent = parent_map[elem]
                     # FIXME: what if the selector is "*" ?
                     elems = list(parent.findall(elem.tag))
                     if elems[index] is elem:
                         yield elem
                 except (IndexError, KeyError):
                     pass
         return select
     raise SyntaxError("invalid predicate")

 ops = {
     "": prepare_child,
     "*": prepare_star,
     ".": prepare_self,
     "..": prepare_parent,
     "//": prepare_descendant,
     "[": prepare_predicate,
     }

 _cache = {}

 class _SelectorContext:
     parent_map = None
     def __init__(self, root):
         self.root = root

 # --------------------------------------------------------------------

 ##
 # Generate all matching objects.

 def iterfind(elem, path, namespaces=None):
     # compile selector pattern
     cache_key = (path, None if namespaces is None
                             else tuple(sorted(namespaces.items())))
     if path[-1:] == "/":
         path = path + "*" # implicit all (FIXME: keep this?)
     try:
         selector = _cache[cache_key]
     except KeyError:
         if len(_cache) > 100:
             _cache.clear()
         if path[:1] == "/":
             raise SyntaxError("cannot use absolute path on element")
         next = iter(xpath_tokenizer(path, namespaces)).__next__
         try:
             token = next()
         except StopIteration:
             return
         selector = []
         while 1:
             try:
                 selector.append(ops[token[0]](next, token))
             except StopIteration:
                 raise SyntaxError("invalid path")
             try:
                 token = next()
                 if token[0] == "/":
                     token = next()
             except StopIteration:
                 break
         _cache[cache_key] = selector
     # execute selector pattern
     result = [elem]
     context = _SelectorContext(elem)
     for select in selector:
         result = select(context, result)
     return result

 ##
 # Find first matching object.

 def find(elem, path, namespaces=None):
     return next(iterfind(elem, path, namespaces), None)

 ##
 # Find all matching objects.

 def findall(elem, path, namespaces=None):
     return list(iterfind(elem, path, namespaces))

 ##
 # Find text for first matching object.

 def findtext(elem, path, default=None, namespaces=None):
     try:
         elem = next(iterfind(elem, path, namespaces))
         return elem.text or ""
     except StopIteration:
         return default
	#
	# ElementTree
	# $Id: ElementPath.py 3375 2008-02-13 08:05:08Z fredrik $
	#
	# limited xpath support for element trees
	#
	# history:
	# 2003-05-23 fl created
	# 2003-05-28 fl added support for // etc
	# 2003-08-27 fl fixed parsing of periods in element names
	# 2007-09-10 fl new selection engine
	# 2007-09-12 fl fixed parent selector
	# 2007-09-13 fl added iterfind; changed findall to return a list
	# 2007-11-30 fl added namespaces support
	# 2009-10-30 fl added child element value filter
	#
	# Copyright (c) 2003-2009 by Fredrik Lundh. All rights reserved.
	#
	# fredrik@pythonware.com
	# http://www.pythonware.com
	#
	# --------------------------------------------------------------------
	# The ElementTree toolkit is
	#
	# Copyright (c) 1999-2009 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.
	# --------------------------------------------------------------------

	# Licensed to PSF under a Contributor Agreement.
	# See http://www.python.org/psf/license for licensing details.

	##
	# Implementation module for XPath support. There's usually no reason
	# to import this module directly; the <b>ElementTree</b> does this for
	# you, if needed.
	##

	import re

	xpath_tokenizer_re = re.compile(
	"("
	"'[^']'\|\"[^\"]\"\|"
	"::\|"
	"//?\|"
	"\.\.\|"
	"\(\)\|"
	"[/.*:\[\]\(\)@=])\|"
	"((?:\{[^}]+\})?[^/\[\]\(\)@=\s]+)\|"
	"\s+"
	)

	def xpath_tokenizer(pattern, namespaces=None):
	for token in xpath_tokenizer_re.findall(pattern):
	tag = token[1]
	if tag and tag[0] != "{" and ":" in tag:
	try:
	prefix, uri = tag.split(":", 1)
	if not namespaces:
	raise KeyError
	yield token[0], "{%s}%s" % (namespaces[prefix], uri)
	except KeyError:
	raise SyntaxError("prefix %r not found in prefix map" % prefix)
	else:
	yield token

	def get_parent_map(context):
	parent_map = context.parent_map
	if parent_map is None:
	context.parent_map = parent_map = {}
	for p in context.root.iter():
	for e in p:
	parent_map[e] = p
	return parent_map

	def prepare_child(next, token):
	tag = token[1]
	def select(context, result):
	for elem in result:
	for e in elem:
	if e.tag == tag:
	yield e
	return select

	def prepare_star(next, token):
	def select(context, result):
	for elem in result:
	yield from elem
	return select

	def prepare_self(next, token):
	def select(context, result):
	yield from result
	return select

	def prepare_descendant(next, token):
	try:
	token = next()
	except StopIteration:
	return
	if token[0] == "*":
	tag = "*"
	elif not token[0]:
	tag = token[1]
	else:
	raise SyntaxError("invalid descendant")
	def select(context, result):
	for elem in result:
	for e in elem.iter(tag):
	if e is not elem:
	yield e
	return select

	def prepare_parent(next, token):
	def select(context, result):
	# FIXME: raise error if .. is applied at toplevel?
	parent_map = get_parent_map(context)
	result_map = {}
	for elem in result:
	if elem in parent_map:
	parent = parent_map[elem]
	if parent not in result_map:
	result_map[parent] = None
	yield parent
	return select

	def prepare_predicate(next, token):
	# FIXME: replace with real parser!!! refs:
	# http://effbot.org/zone/simple-iterator-parser.htm
	# http://javascript.crockford.com/tdop/tdop.html
	signature = []
	predicate = []
	while 1:
	try:
	token = next()
	except StopIteration:
	return
	if token[0] == "]":
	break
	if token[0] and token[0][:1] in "'\"":
	token = "'", token[0][1:-1]
	signature.append(token[0] or "-")
	predicate.append(token[1])
	signature = "".join(signature)
	# use signature to determine predicate type
	if signature == "@-":
	# [@attribute] predicate
	key = predicate[1]
	def select(context, result):
	for elem in result:
	if elem.get(key) is not None:
	yield elem
	return select
	if signature == "@-='":
	# [@attribute='value']
	key = predicate[1]
	value = predicate[-1]
	def select(context, result):
	for elem in result:
	if elem.get(key) == value:
	yield elem
	return select
	if signature == "-" and not re.match("\-?\d+$", predicate[0]):
	# [tag]
	tag = predicate[0]
	def select(context, result):
	for elem in result:
	if elem.find(tag) is not None:
	yield elem
	return select
	if signature == "-='" and not re.match("\-?\d+$", predicate[0]):
	# [tag='value']
	tag = predicate[0]
	value = predicate[-1]
	def select(context, result):
	for elem in result:
	for e in elem.findall(tag):
	if "".join(e.itertext()) == value:
	yield elem
	break
	return select
	if signature == "-" or signature == "-()" or signature == "-()-":
	# [index] or [last()] or [last()-index]
	if signature == "-":
	# [index]
	index = int(predicate[0]) - 1
	if index < 0:
	raise SyntaxError("XPath position >= 1 expected")
	else:
	if predicate[0] != "last":
	raise SyntaxError("unsupported function")
	if signature == "-()-":
	try:
	index = int(predicate[2]) - 1
	except ValueError:
	raise SyntaxError("unsupported expression")
	if index > -2:
	raise SyntaxError("XPath offset from last() must be negative")
	else:
	index = -1
	def select(context, result):
	parent_map = get_parent_map(context)
	for elem in result:
	try:
	parent = parent_map[elem]
	# FIXME: what if the selector is "*" ?
	elems = list(parent.findall(elem.tag))
	if elems[index] is elem:
	yield elem
	except (IndexError, KeyError):
	pass
	return select
	raise SyntaxError("invalid predicate")

	ops = {
	"": prepare_child,
	"*": prepare_star,
	".": prepare_self,
	"..": prepare_parent,
	"//": prepare_descendant,
	"[": prepare_predicate,
	}

	_cache = {}

	class _SelectorContext:
	parent_map = None
	def __init__(self, root):
	self.root = root

	# --------------------------------------------------------------------

	##
	# Generate all matching objects.

	def iterfind(elem, path, namespaces=None):
	# compile selector pattern
	cache_key = (path, None if namespaces is None
	else tuple(sorted(namespaces.items())))
	if path[-1:] == "/":
	path = path + "*" # implicit all (FIXME: keep this?)
	try:
	selector = _cache[cache_key]
	except KeyError:
	if len(_cache) > 100:
	_cache.clear()
	if path[:1] == "/":
	raise SyntaxError("cannot use absolute path on element")
	next = iter(xpath_tokenizer(path, namespaces)).__next__
	try:
	token = next()
	except StopIteration:
	return
	selector = []
	while 1:
	try:
	selector.append(ops[token[0]](next, token))
	except StopIteration:
	raise SyntaxError("invalid path")
	try:
	token = next()
	if token[0] == "/":
	token = next()
	except StopIteration:
	break
	_cache[cache_key] = selector
	# execute selector pattern
	result = [elem]
	context = _SelectorContext(elem)
	for select in selector:
	result = select(context, result)
	return result

	##
	# Find first matching object.

	def find(elem, path, namespaces=None):
	return next(iterfind(elem, path, namespaces), None)

	##
	# Find all matching objects.

	def findall(elem, path, namespaces=None):
	return list(iterfind(elem, path, namespaces))

	##
	# Find text for first matching object.

	def findtext(elem, path, default=None, namespaces=None):
	try:
	elem = next(iterfind(elem, path, namespaces))
	return elem.text or ""
	except StopIteration:
	return default