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#
# ElementTree
# $Id$
#
# 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
#
# Copyright (c) 2003-2007 by Fredrik Lundh. All rights reserved.
#
# fredrik@pythonware.com
# http://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.
# --------------------------------------------------------------------
##
# 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.compile(
"("
"'[^']*'|\"[^\"]*\"|"
"::|"
"//?|"
"\.\.|"
"\(\)|"
"[/.*:\[\]\(\)@=])|"
"((?:\{[^}]+\})?[^/:\[\]\(\)@=\s]+)|"
"\s+"
).findall
def prepare_tag(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:
for e in elem:
yield e
return select
def prepare_dot(next, token):
def select(context, result):
for elem in result:
yield elem
return select
def prepare_iter(next, token):
token = next()
if token[0] == "*":
tag = "*"
elif not token[0]:
tag = token[1]
else:
raise SyntaxError
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_dot_dot(next, token):
def select(context, result):
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
for elem in result:
if elem in parent_map:
yield parent_map[elem]
return select
def prepare_predicate(next, token):
# this one should probably be refactored...
token = next()
if token[0] == "@":
# attribute
token = next()
if token[0]:
raise SyntaxError("invalid attribute predicate")
key = token[1]
token = next()
if token[0] == "]":
def select(context, result):
for elem in result:
if elem.get(key) is not None:
yield elem
elif token[0] == "=":
value = next()[0]
if value[:1] == "'" or value[:1] == '"':
value = value[1:-1]
else:
raise SyntaxError("invalid comparision target")
token = next()
def select(context, result):
for elem in result:
if elem.get(key) == value:
yield elem
if token[0] != "]":
raise SyntaxError("invalid attribute predicate")
elif not token[0]:
tag = token[1]
token = next()
if token[0] != "]":
raise SyntaxError("invalid node predicate")
def select(context, result):
for elem in result:
if elem.find(tag) is not None:
yield elem
else:
raise SyntaxError("invalid predicate")
return select
ops = {
"": prepare_tag,
"*": prepare_star,
".": prepare_dot,
"..": prepare_dot_dot,
"//": prepare_iter,
"[": prepare_predicate,
}
_cache = {}
class _SelectorContext:
parent_map = None
def __init__(self, root):
self.root = root
# --------------------------------------------------------------------
##
# Find first matching object.
def find(elem, path):
try:
return findall(elem, path).next()
except StopIteration:
return None
##
# Find all matching objects.
def findall(elem, path):
# compile selector pattern
try:
selector = _cache[path]
except KeyError:
if len(_cache) > 100:
_cache.clear()
if path[:1] == "/":
raise SyntaxError("cannot use absolute path on element")
stream = iter(xpath_tokenizer(path))
next = stream.next; token = next()
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[path] = selector
# execute selector pattern
result = [elem]
context = _SelectorContext(elem)
for select in selector:
result = select(context, result)
return result
##
# Find text for first matching object.
def findtext(elem, path, default=None):
try:
elem = findall(elem, path).next()
return elem.text
except StopIteration:
return default
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