# -*- coding: utf-8 -*-
#
# Copyright (C) 2006-2009 Edgewall Software
# All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://genshi.edgewall.org/wiki/License.
#
# This software consists of voluntary contributions made by many
# individuals. For the exact contribution history, see the revision
# history and logs, available at http://genshi.edgewall.org/log/.
"""Basic support for evaluating XPath expressions against streams.
>>> from genshi.input import XML
>>> doc = XML('''
...
... -
... Foo
...
... -
... Bar
...
... -
... Baz
...
... -
... Waz
...
...
... ''')
>>> print(doc.select('items/item[@status="closed" and '
... '(@resolution="invalid" or not(@resolution))]/summary/text()'))
BarBaz
Because the XPath engine operates on markup streams (as opposed to tree
structures), it only implements a subset of the full XPath 1.0 language.
"""
from collections import deque
try:
reduce # builtin in Python < 3
except NameError:
from functools import reduce
from math import ceil, floor
import operator
import re
from itertools import chain
from genshi.core import Stream, Attrs, Namespace, QName
from genshi.core import START, END, TEXT, START_NS, END_NS, COMMENT, PI, \
START_CDATA, END_CDATA
__all__ = ['Path', 'PathSyntaxError']
__docformat__ = 'restructuredtext en'
class Axis(object):
"""Defines constants for the various supported XPath axes."""
ATTRIBUTE = 'attribute'
CHILD = 'child'
DESCENDANT = 'descendant'
DESCENDANT_OR_SELF = 'descendant-or-self'
SELF = 'self'
@classmethod
def forname(cls, name):
"""Return the axis constant for the given name, or `None` if no such
axis was defined.
"""
return getattr(cls, name.upper().replace('-', '_'), None)
ATTRIBUTE = Axis.ATTRIBUTE
CHILD = Axis.CHILD
DESCENDANT = Axis.DESCENDANT
DESCENDANT_OR_SELF = Axis.DESCENDANT_OR_SELF
SELF = Axis.SELF
class GenericStrategy(object):
@classmethod
def supports(cls, path):
return True
def __init__(self, path):
self.path = path
def test(self, ignore_context):
p = self.path
if ignore_context:
if p[0][0] is ATTRIBUTE:
steps = [_DOTSLASHSLASH] + p
else:
steps = [(DESCENDANT_OR_SELF, p[0][1], p[0][2])] + p[1:]
elif p[0][0] is CHILD or p[0][0] is ATTRIBUTE \
or p[0][0] is DESCENDANT:
steps = [_DOTSLASH] + p
else:
steps = p
# for node it contains all positions of xpath expression
# where its child should start checking for matches
# with list of corresponding context counters
# there can be many of them, because position that is from
# descendant-like axis can be achieved from different nodes
# for example should match both //a//b[1]
# and //a//b[2]
# positions always form increasing sequence (invariant)
stack = [[(0, [[]])]]
def _test(event, namespaces, variables, updateonly=False):
kind, data, pos = event[:3]
retval = None
# Manage the stack that tells us "where we are" in the stream
if kind is END:
if stack:
stack.pop()
return None
if kind is START_NS or kind is END_NS \
or kind is START_CDATA or kind is END_CDATA:
# should we make namespaces work?
return None
pos_queue = deque([(pos, cou, []) for pos, cou in stack[-1]])
next_pos = []
# length of real part of path - we omit attribute axis
real_len = len(steps) - ((steps[-1][0] == ATTRIBUTE) or 1 and 0)
last_checked = -1
# places where we have to check for match, are these
# provided by parent
while pos_queue:
x, pcou, mcou = pos_queue.popleft()
axis, nodetest, predicates = steps[x]
# we need to push descendant-like positions from parent
# further
if (axis is DESCENDANT or axis is DESCENDANT_OR_SELF) and pcou:
if next_pos and next_pos[-1][0] == x:
next_pos[-1][1].extend(pcou)
else:
next_pos.append((x, pcou))
# nodetest first
if not nodetest(kind, data, pos, namespaces, variables):
continue
# counters packs that were already bad
missed = set()
counters_len = len(pcou) + len(mcou)
# number of counters - we have to create one
# for every context position based predicate
cnum = 0
# tells if we have match with position x
matched = True
if predicates:
for predicate in predicates:
pretval = predicate(kind, data, pos,
namespaces,
variables)
if type(pretval) is float: # FIXME <- need to check
# this for other types that
# can be coerced to float
# each counter pack needs to be checked
for i, cou in enumerate(chain(pcou, mcou)):
# it was bad before
if i in missed:
continue
if len(cou) < cnum + 1:
cou.append(0)
cou[cnum] += 1
# it is bad now
if cou[cnum] != int(pretval):
missed.add(i)
# none of counters pack was good
if len(missed) == counters_len:
pretval = False
cnum += 1
if not pretval:
matched = False
break
if not matched:
continue
# counter for next position with current node as context node
child_counter = []
if x + 1 == real_len:
# we reached end of expression, because x + 1
# is equal to the length of expression
matched = True
axis, nodetest, predicates = steps[-1]
if axis is ATTRIBUTE:
matched = nodetest(kind, data, pos, namespaces,
variables)
if matched:
retval = matched
else:
next_axis = steps[x + 1][0]
# if next axis allows matching self we have
# to add next position to our queue
if next_axis is DESCENDANT_OR_SELF or next_axis is SELF:
if not pos_queue or pos_queue[0][0] > x + 1:
pos_queue.appendleft((x + 1, [], [child_counter]))
else:
pos_queue[0][2].append(child_counter)
# if axis is not self we have to add it to child's list
if next_axis is not SELF:
next_pos.append((x + 1, [child_counter]))
if kind is START:
stack.append(next_pos)
return retval
return _test
class SimplePathStrategy(object):
"""Strategy for path with only local names, attributes and text nodes."""
@classmethod
def supports(cls, path):
if path[0][0] is ATTRIBUTE:
return False
allowed_tests = (LocalNameTest, CommentNodeTest, TextNodeTest)
for _, nodetest, predicates in path:
if predicates:
return False
if not isinstance(nodetest, allowed_tests):
return False
return True
def __init__(self, path):
# fragments is list of tuples (fragment, pi, attr, self_beginning)
# fragment is list of nodetests for fragment of path with only
# child:: axes between
# pi is KMP partial match table for this fragment
# attr is attribute nodetest if fragment ends with @ and None otherwise
# self_beginning is True if axis for first fragment element
# was self (first fragment) or descendant-or-self (farther fragment)
self.fragments = []
self_beginning = False
fragment = []
def nodes_equal(node1, node2):
"""Tests if two node tests are equal"""
if type(node1) is not type(node2):
return False
if type(node1) == LocalNameTest:
return node1.name == node2.name
return True
def calculate_pi(f):
"""KMP prefix calculation for table"""
# the indexes in prefix table are shifted by one
# in comparision with common implementations
# pi[i] = NORMAL_PI[i + 1]
if len(f) == 0:
return []
pi = [0]
s = 0
for i in range(1, len(f)):
while s > 0 and not nodes_equal(f[s], f[i]):
s = pi[s-1]
if nodes_equal(f[s], f[i]):
s += 1
pi.append(s)
return pi
for axis in path:
if axis[0] is SELF:
if len(fragment) != 0:
# if element is not first in fragment it has to be
# the same as previous one
# for example child::a/self::b is always wrong
if axis[1] != fragment[-1][1]:
self.fragments = None
return
else:
self_beginning = True
fragment.append(axis[1])
elif axis[0] is CHILD:
fragment.append(axis[1])
elif axis[0] is ATTRIBUTE:
pi = calculate_pi(fragment)
self.fragments.append((fragment, pi, axis[1], self_beginning))
# attribute has always to be at the end, so we can jump out
return
else:
pi = calculate_pi(fragment)
self.fragments.append((fragment, pi, None, self_beginning))
fragment = [axis[1]]
if axis[0] is DESCENDANT:
self_beginning = False
else: # DESCENDANT_OR_SELF
self_beginning = True
pi = calculate_pi(fragment)
self.fragments.append((fragment, pi, None, self_beginning))
def test(self, ignore_context):
# stack of triples (fid, p, ic)
# fid is index of current fragment
# p is position in this fragment
# ic is if we ignore context in this fragment
stack = []
stack_push = stack.append
stack_pop = stack.pop
frags = self.fragments
frags_len = len(frags)
def _test(event, namespaces, variables, updateonly=False):
# expression found impossible during init
if frags is None:
return None
kind, data, pos = event[:3]
# skip events we don't care about
if kind is END:
if stack:
stack_pop()
return None
if kind is START_NS or kind is END_NS \
or kind is START_CDATA or kind is END_CDATA:
return None
if not stack:
# root node, nothing on stack, special case
fid = 0
# skip empty fragments (there can be actually only one)
while not frags[fid][0]:
fid += 1
p = 0
# empty fragment means descendant node at beginning
ic = ignore_context or (fid > 0)
# expression can match first node, if first axis is self::,
# descendant-or-self:: or if ignore_context is True and
# axis is not descendant::
if not frags[fid][3] and (not ignore_context or fid > 0):
# axis is not self-beggining, we have to skip this node
stack_push((fid, p, ic))
return None
else:
# take position of parent
fid, p, ic = stack[-1]
if fid is not None and not ic:
# fragment not ignoring context - we can't jump back
frag, pi, attrib, _ = frags[fid]
frag_len = len(frag)
if p == frag_len:
# that probably means empty first fragment
pass
elif frag[p](kind, data, pos, namespaces, variables):
# match, so we can go further
p += 1
else:
# not matched, so there will be no match in subtree
fid, p = None, None
if p == frag_len and fid + 1 != frags_len:
# we made it to end of fragment, we can go to following
fid += 1
p = 0
ic = True
if fid is None:
# there was no match in fragment not ignoring context
if kind is START:
stack_push((fid, p, ic))
return None
if ic:
# we are in fragment ignoring context
while True:
frag, pi, attrib, _ = frags[fid]
frag_len = len(frag)
# KMP new "character"
while p > 0 and (p >= frag_len or not \
frag[p](kind, data, pos, namespaces, variables)):
p = pi[p-1]
if frag[p](kind, data, pos, namespaces, variables):
p += 1
if p == frag_len:
# end of fragment reached
if fid + 1 == frags_len:
# that was last fragment
break
else:
fid += 1
p = 0
ic = True
if not frags[fid][3]:
# next fragment not self-beginning
break
else:
break
if kind is START:
# we have to put new position on stack, for children
if not ic and fid + 1 == frags_len and p == frag_len:
# it is end of the only, not context ignoring fragment
# so there will be no matches in subtree
stack_push((None, None, ic))
else:
stack_push((fid, p, ic))
# have we reached the end of the last fragment?
if fid + 1 == frags_len and p == frag_len:
if attrib: # attribute ended path, return value
return attrib(kind, data, pos, namespaces, variables)
return True
return None
return _test
class SingleStepStrategy(object):
@classmethod
def supports(cls, path):
return len(path) == 1
def __init__(self, path):
self.path = path
def test(self, ignore_context):
steps = self.path
if steps[0][0] is ATTRIBUTE:
steps = [_DOTSLASH] + steps
select_attr = steps[-1][0] is ATTRIBUTE and steps[-1][1] or None
# for every position in expression stores counters' list
# it is used for position based predicates
counters = []
depth = [0]
def _test(event, namespaces, variables, updateonly=False):
kind, data, pos = event[:3]
# Manage the stack that tells us "where we are" in the stream
if kind is END:
if not ignore_context:
depth[0] -= 1
return None
elif kind is START_NS or kind is END_NS \
or kind is START_CDATA or kind is END_CDATA:
# should we make namespaces work?
return None
if not ignore_context:
outside = (steps[0][0] is SELF and depth[0] != 0) \
or (steps[0][0] is CHILD and depth[0] != 1) \
or (steps[0][0] is DESCENDANT and depth[0] < 1)
if kind is START:
depth[0] += 1
if outside:
return None
axis, nodetest, predicates = steps[0]
if not nodetest(kind, data, pos, namespaces, variables):
return None
if predicates:
cnum = 0
for predicate in predicates:
pretval = predicate(kind, data, pos, namespaces, variables)
if type(pretval) is float: # FIXME <- need to check this
# for other types that can be
# coerced to float
if len(counters) < cnum + 1:
counters.append(0)
counters[cnum] += 1
if counters[cnum] != int(pretval):
pretval = False
cnum += 1
if not pretval:
return None
if select_attr:
return select_attr(kind, data, pos, namespaces, variables)
return True
return _test
class Path(object):
"""Implements basic XPath support on streams.
Instances of this class represent a "compiled" XPath expression, and
provide methods for testing the path against a stream, as well as
extracting a substream matching that path.
"""
STRATEGIES = (SingleStepStrategy, SimplePathStrategy, GenericStrategy)
def __init__(self, text, filename=None, lineno=-1):
"""Create the path object from a string.
:param text: the path expression
:param filename: the name of the file in which the path expression was
found (used in error messages)
:param lineno: the line on which the expression was found
"""
self.source = text
self.paths = PathParser(text, filename, lineno).parse()
self.strategies = []
for path in self.paths:
for strategy_class in self.STRATEGIES:
if strategy_class.supports(path):
self.strategies.append(strategy_class(path))
break
else:
raise NotImplemented('No strategy found for path')
def __repr__(self):
paths = []
for path in self.paths:
steps = []
for axis, nodetest, predicates in path:
steps.append('%s::%s' % (axis, nodetest))
for predicate in predicates:
steps[-1] += '[%s]' % predicate
paths.append('/'.join(steps))
return '<%s "%s">' % (type(self).__name__, '|'.join(paths))
def select(self, stream, namespaces=None, variables=None):
"""Returns a substream of the given stream that matches the path.
If there are no matches, this method returns an empty stream.
>>> from genshi.input import XML
>>> xml = XML('Text')
>>> print(Path('.//child').select(xml))
Text
>>> print(Path('.//child/text()').select(xml))
Text
:param stream: the stream to select from
:param namespaces: (optional) a mapping of namespace prefixes to URIs
:param variables: (optional) a mapping of variable names to values
:return: the substream matching the path, or an empty stream
:rtype: `Stream`
"""
if namespaces is None:
namespaces = {}
if variables is None:
variables = {}
stream = iter(stream)
def _generate(stream=stream, ns=namespaces, vs=variables):
next = stream.next
test = self.test()
for event in stream:
result = test(event, ns, vs)
if result is True:
yield event
if event[0] is START:
depth = 1
while depth > 0:
subevent = next()
if subevent[0] is START:
depth += 1
elif subevent[0] is END:
depth -= 1
yield subevent
test(subevent, ns, vs, updateonly=True)
elif result:
yield result
return Stream(_generate(),
serializer=getattr(stream, 'serializer', None))
def test(self, ignore_context=False):
"""Returns a function that can be used to track whether the path matches
a specific stream event.
The function returned expects the positional arguments ``event``,
``namespaces`` and ``variables``. The first is a stream event, while the
latter two are a mapping of namespace prefixes to URIs, and a mapping
of variable names to values, respectively. In addition, the function
accepts an ``updateonly`` keyword argument that default to ``False``. If
it is set to ``True``, the function only updates its internal state,
but does not perform any tests or return a result.
If the path matches the event, the function returns the match (for
example, a `START` or `TEXT` event.) Otherwise, it returns ``None``.
>>> from genshi.input import XML
>>> xml = XML('')
>>> test = Path('child').test()
>>> namespaces, variables = {}, {}
>>> for event in xml:
... if test(event, namespaces, variables):
... print('%s %r' % (event[0], event[1]))
START (QName('child'), Attrs([(QName('id'), u'2')]))
:param ignore_context: if `True`, the path is interpreted like a pattern
in XSLT, meaning for example that it will match
at any depth
:return: a function that can be used to test individual events in a
stream against the path
:rtype: ``function``
"""
tests = [s.test(ignore_context) for s in self.strategies]
if len(tests) == 1:
return tests[0]
def _multi(event, namespaces, variables, updateonly=False):
retval = None
for test in tests:
val = test(event, namespaces, variables, updateonly=updateonly)
if retval is None:
retval = val
return retval
return _multi
class PathSyntaxError(Exception):
"""Exception raised when an XPath expression is syntactically incorrect."""
def __init__(self, message, filename=None, lineno=-1, offset=-1):
if filename:
message = '%s (%s, line %d)' % (message, filename, lineno)
Exception.__init__(self, message)
self.filename = filename
self.lineno = lineno
self.offset = offset
class PathParser(object):
"""Tokenizes and parses an XPath expression."""
_QUOTES = (("'", "'"), ('"', '"'))
_TOKENS = ('::', ':', '..', '.', '//', '/', '[', ']', '()', '(', ')', '@',
'=', '!=', '!', '|', ',', '>=', '>', '<=', '<', '$')
_tokenize = re.compile('("[^"]*")|(\'[^\']*\')|((?:\d+)?\.\d+)|(%s)|([^%s\s]+)|\s+' % (
'|'.join([re.escape(t) for t in _TOKENS]),
''.join([re.escape(t[0]) for t in _TOKENS]))).findall
def __init__(self, text, filename=None, lineno=-1):
self.filename = filename
self.lineno = lineno
self.tokens = [t for t in [dqstr or sqstr or number or token or name
for dqstr, sqstr, number, token, name in
self._tokenize(text)] if t]
self.pos = 0
# Tokenizer
@property
def at_end(self):
return self.pos == len(self.tokens) - 1
@property
def cur_token(self):
return self.tokens[self.pos]
def next_token(self):
self.pos += 1
return self.tokens[self.pos]
def peek_token(self):
if not self.at_end:
return self.tokens[self.pos + 1]
return None
# Recursive descent parser
def parse(self):
"""Parses the XPath expression and returns a list of location path
tests.
For union expressions (such as `*|text()`), this function returns one
test for each operand in the union. For patch expressions that don't
use the union operator, the function always returns a list of size 1.
Each path test in turn is a sequence of tests that correspond to the
location steps, each tuples of the form `(axis, testfunc, predicates)`
"""
paths = [self._location_path()]
while self.cur_token == '|':
self.next_token()
paths.append(self._location_path())
if not self.at_end:
raise PathSyntaxError('Unexpected token %r after end of expression'
% self.cur_token, self.filename, self.lineno)
return paths
def _location_path(self):
steps = []
while True:
if self.cur_token.startswith('/'):
if not steps:
if self.cur_token == '//':
# hack to make //* match every node - also root
self.next_token()
axis, nodetest, predicates = self._location_step()
steps.append((DESCENDANT_OR_SELF, nodetest,
predicates))
if self.at_end or not self.cur_token.startswith('/'):
break
continue
else:
raise PathSyntaxError('Absolute location paths not '
'supported', self.filename,
self.lineno)
elif self.cur_token == '//':
steps.append((DESCENDANT_OR_SELF, NodeTest(), []))
self.next_token()
axis, nodetest, predicates = self._location_step()
if not axis:
axis = CHILD
steps.append((axis, nodetest, predicates))
if self.at_end or not self.cur_token.startswith('/'):
break
return steps
def _location_step(self):
if self.cur_token == '@':
axis = ATTRIBUTE
self.next_token()
elif self.cur_token == '.':
axis = SELF
elif self.cur_token == '..':
raise PathSyntaxError('Unsupported axis "parent"', self.filename,
self.lineno)
elif self.peek_token() == '::':
axis = Axis.forname(self.cur_token)
if axis is None:
raise PathSyntaxError('Unsupport axis "%s"' % axis,
self.filename, self.lineno)
self.next_token()
self.next_token()
else:
axis = None
nodetest = self._node_test(axis or CHILD)
predicates = []
while self.cur_token == '[':
predicates.append(self._predicate())
return axis, nodetest, predicates
def _node_test(self, axis=None):
test = prefix = None
next_token = self.peek_token()
if next_token in ('(', '()'): # Node type test
test = self._node_type()
elif next_token == ':': # Namespace prefix
prefix = self.cur_token
self.next_token()
localname = self.next_token()
if localname == '*':
test = QualifiedPrincipalTypeTest(axis, prefix)
else:
test = QualifiedNameTest(axis, prefix, localname)
else: # Name test
if self.cur_token == '*':
test = PrincipalTypeTest(axis)
elif self.cur_token == '.':
test = NodeTest()
else:
test = LocalNameTest(axis, self.cur_token)
if not self.at_end:
self.next_token()
return test
def _node_type(self):
name = self.cur_token
self.next_token()
args = []
if self.cur_token != '()':
# The processing-instruction() function optionally accepts the
# name of the PI as argument, which must be a literal string
self.next_token() # (
if self.cur_token != ')':
string = self.cur_token
if (string[0], string[-1]) in self._QUOTES:
string = string[1:-1]
args.append(string)
cls = _nodetest_map.get(name)
if not cls:
raise PathSyntaxError('%s() not allowed here' % name, self.filename,
self.lineno)
return cls(*args)
def _predicate(self):
assert self.cur_token == '['
self.next_token()
expr = self._or_expr()
if self.cur_token != ']':
raise PathSyntaxError('Expected "]" to close predicate, '
'but found "%s"' % self.cur_token,
self.filename, self.lineno)
if not self.at_end:
self.next_token()
return expr
def _or_expr(self):
expr = self._and_expr()
while self.cur_token == 'or':
self.next_token()
expr = OrOperator(expr, self._and_expr())
return expr
def _and_expr(self):
expr = self._equality_expr()
while self.cur_token == 'and':
self.next_token()
expr = AndOperator(expr, self._equality_expr())
return expr
def _equality_expr(self):
expr = self._relational_expr()
while self.cur_token in ('=', '!='):
op = _operator_map[self.cur_token]
self.next_token()
expr = op(expr, self._relational_expr())
return expr
def _relational_expr(self):
expr = self._sub_expr()
while self.cur_token in ('>', '>=', '<', '>='):
op = _operator_map[self.cur_token]
self.next_token()
expr = op(expr, self._sub_expr())
return expr
def _sub_expr(self):
token = self.cur_token
if token != '(':
return self._primary_expr()
self.next_token()
expr = self._or_expr()
if self.cur_token != ')':
raise PathSyntaxError('Expected ")" to close sub-expression, '
'but found "%s"' % self.cur_token,
self.filename, self.lineno)
self.next_token()
return expr
def _primary_expr(self):
token = self.cur_token
if len(token) > 1 and (token[0], token[-1]) in self._QUOTES:
self.next_token()
return StringLiteral(token[1:-1])
elif token[0].isdigit() or token[0] == '.':
self.next_token()
return NumberLiteral(as_float(token))
elif token == '$':
token = self.next_token()
self.next_token()
return VariableReference(token)
elif not self.at_end and self.peek_token().startswith('('):
return self._function_call()
else:
axis = None
if token == '@':
axis = ATTRIBUTE
self.next_token()
return self._node_test(axis)
def _function_call(self):
name = self.cur_token
if self.next_token() == '()':
args = []
else:
assert self.cur_token == '('
self.next_token()
args = [self._or_expr()]
while self.cur_token == ',':
self.next_token()
args.append(self._or_expr())
if not self.cur_token == ')':
raise PathSyntaxError('Expected ")" to close function argument '
'list, but found "%s"' % self.cur_token,
self.filename, self.lineno)
self.next_token()
cls = _function_map.get(name)
if not cls:
raise PathSyntaxError('Unsupported function "%s"' % name,
self.filename, self.lineno)
return cls(*args)
# Type coercion
def as_scalar(value):
"""Convert value to a scalar. If a single element Attrs() object is passed
the value of the single attribute will be returned."""
if isinstance(value, Attrs):
assert len(value) == 1
return value[0][1]
else:
return value
def as_float(value):
# FIXME - if value is a bool it will be coerced to 0.0 and consequently
# compared as a float. This is probably not ideal.
return float(as_scalar(value))
def as_long(value):
return long(as_scalar(value))
def as_string(value):
value = as_scalar(value)
if value is False:
return ''
return unicode(value)
def as_bool(value):
return bool(as_scalar(value))
# Node tests
class PrincipalTypeTest(object):
"""Node test that matches any event with the given principal type."""
__slots__ = ['principal_type']
def __init__(self, principal_type):
self.principal_type = principal_type
def __call__(self, kind, data, pos, namespaces, variables):
if kind is START:
if self.principal_type is ATTRIBUTE:
return data[1] or None
else:
return True
def __repr__(self):
return '*'
class QualifiedPrincipalTypeTest(object):
"""Node test that matches any event with the given principal type in a
specific namespace."""
__slots__ = ['principal_type', 'prefix']
def __init__(self, principal_type, prefix):
self.principal_type = principal_type
self.prefix = prefix
def __call__(self, kind, data, pos, namespaces, variables):
namespace = Namespace(namespaces.get(self.prefix))
if kind is START:
if self.principal_type is ATTRIBUTE and data[1]:
return Attrs([(name, value) for name, value in data[1]
if name in namespace]) or None
else:
return data[0] in namespace
def __repr__(self):
return '%s:*' % self.prefix
class LocalNameTest(object):
"""Node test that matches any event with the given principal type and
local name.
"""
__slots__ = ['principal_type', 'name']
def __init__(self, principal_type, name):
self.principal_type = principal_type
self.name = name
def __call__(self, kind, data, pos, namespaces, variables):
if kind is START:
if self.principal_type is ATTRIBUTE and self.name in data[1]:
return Attrs([(self.name, data[1].get(self.name))])
else:
return data[0].localname == self.name
def __repr__(self):
return self.name
class QualifiedNameTest(object):
"""Node test that matches any event with the given principal type and
qualified name.
"""
__slots__ = ['principal_type', 'prefix', 'name']
def __init__(self, principal_type, prefix, name):
self.principal_type = principal_type
self.prefix = prefix
self.name = name
def __call__(self, kind, data, pos, namespaces, variables):
qname = QName('%s}%s' % (namespaces.get(self.prefix), self.name))
if kind is START:
if self.principal_type is ATTRIBUTE and qname in data[1]:
return Attrs([(self.name, data[1].get(self.name))])
else:
return data[0] == qname
def __repr__(self):
return '%s:%s' % (self.prefix, self.name)
class CommentNodeTest(object):
"""Node test that matches any comment events."""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
return kind is COMMENT
def __repr__(self):
return 'comment()'
class NodeTest(object):
"""Node test that matches any node."""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
if kind is START:
return True
return kind, data, pos
def __repr__(self):
return 'node()'
class ProcessingInstructionNodeTest(object):
"""Node test that matches any processing instruction event."""
__slots__ = ['target']
def __init__(self, target=None):
self.target = target
def __call__(self, kind, data, pos, namespaces, variables):
return kind is PI and (not self.target or data[0] == self.target)
def __repr__(self):
arg = ''
if self.target:
arg = '"' + self.target + '"'
return 'processing-instruction(%s)' % arg
class TextNodeTest(object):
"""Node test that matches any text event."""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
return kind is TEXT
def __repr__(self):
return 'text()'
_nodetest_map = {'comment': CommentNodeTest, 'node': NodeTest,
'processing-instruction': ProcessingInstructionNodeTest,
'text': TextNodeTest}
# Functions
class Function(object):
"""Base class for function nodes in XPath expressions."""
class BooleanFunction(Function):
"""The `boolean` function, which converts its argument to a boolean
value.
"""
__slots__ = ['expr']
_return_type = bool
def __init__(self, expr):
self.expr = expr
def __call__(self, kind, data, pos, namespaces, variables):
val = self.expr(kind, data, pos, namespaces, variables)
return as_bool(val)
def __repr__(self):
return 'boolean(%r)' % self.expr
class CeilingFunction(Function):
"""The `ceiling` function, which returns the nearest lower integer number
for the given number.
"""
__slots__ = ['number']
def __init__(self, number):
self.number = number
def __call__(self, kind, data, pos, namespaces, variables):
number = self.number(kind, data, pos, namespaces, variables)
return ceil(as_float(number))
def __repr__(self):
return 'ceiling(%r)' % self.number
class ConcatFunction(Function):
"""The `concat` function, which concatenates (joins) the variable number of
strings it gets as arguments.
"""
__slots__ = ['exprs']
def __init__(self, *exprs):
self.exprs = exprs
def __call__(self, kind, data, pos, namespaces, variables):
strings = []
for item in [expr(kind, data, pos, namespaces, variables)
for expr in self.exprs]:
strings.append(as_string(item))
return ''.join(strings)
def __repr__(self):
return 'concat(%s)' % ', '.join([repr(expr) for expr in self.exprs])
class ContainsFunction(Function):
"""The `contains` function, which returns whether a string contains a given
substring.
"""
__slots__ = ['string1', 'string2']
def __init__(self, string1, string2):
self.string1 = string1
self.string2 = string2
def __call__(self, kind, data, pos, namespaces, variables):
string1 = self.string1(kind, data, pos, namespaces, variables)
string2 = self.string2(kind, data, pos, namespaces, variables)
return as_string(string2) in as_string(string1)
def __repr__(self):
return 'contains(%r, %r)' % (self.string1, self.string2)
class MatchesFunction(Function):
"""The `matches` function, which returns whether a string matches a regular
expression.
"""
__slots__ = ['string1', 'string2']
flag_mapping = {'s': re.S, 'm': re.M, 'i': re.I, 'x': re.X}
def __init__(self, string1, string2, flags=''):
self.string1 = string1
self.string2 = string2
self.flags = self._map_flags(flags)
def __call__(self, kind, data, pos, namespaces, variables):
string1 = as_string(self.string1(kind, data, pos, namespaces, variables))
string2 = as_string(self.string2(kind, data, pos, namespaces, variables))
return re.search(string2, string1, self.flags)
def _map_flags(self, flags):
return reduce(operator.or_,
[self.flag_map[flag] for flag in flags], re.U)
def __repr__(self):
return 'contains(%r, %r)' % (self.string1, self.string2)
class FalseFunction(Function):
"""The `false` function, which always returns the boolean `false` value."""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
return False
def __repr__(self):
return 'false()'
class FloorFunction(Function):
"""The `ceiling` function, which returns the nearest higher integer number
for the given number.
"""
__slots__ = ['number']
def __init__(self, number):
self.number = number
def __call__(self, kind, data, pos, namespaces, variables):
number = self.number(kind, data, pos, namespaces, variables)
return floor(as_float(number))
def __repr__(self):
return 'floor(%r)' % self.number
class LocalNameFunction(Function):
"""The `local-name` function, which returns the local name of the current
element.
"""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
if kind is START:
return data[0].localname
def __repr__(self):
return 'local-name()'
class NameFunction(Function):
"""The `name` function, which returns the qualified name of the current
element.
"""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
if kind is START:
return data[0]
def __repr__(self):
return 'name()'
class NamespaceUriFunction(Function):
"""The `namespace-uri` function, which returns the namespace URI of the
current element.
"""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
if kind is START:
return data[0].namespace
def __repr__(self):
return 'namespace-uri()'
class NotFunction(Function):
"""The `not` function, which returns the negated boolean value of its
argument.
"""
__slots__ = ['expr']
def __init__(self, expr):
self.expr = expr
def __call__(self, kind, data, pos, namespaces, variables):
return not as_bool(self.expr(kind, data, pos, namespaces, variables))
def __repr__(self):
return 'not(%s)' % self.expr
class NormalizeSpaceFunction(Function):
"""The `normalize-space` function, which removes leading and trailing
whitespace in the given string, and replaces multiple adjacent whitespace
characters inside the string with a single space.
"""
__slots__ = ['expr']
_normalize = re.compile(r'\s{2,}').sub
def __init__(self, expr):
self.expr = expr
def __call__(self, kind, data, pos, namespaces, variables):
string = self.expr(kind, data, pos, namespaces, variables)
return self._normalize(' ', as_string(string).strip())
def __repr__(self):
return 'normalize-space(%s)' % repr(self.expr)
class NumberFunction(Function):
"""The `number` function that converts its argument to a number."""
__slots__ = ['expr']
def __init__(self, expr):
self.expr = expr
def __call__(self, kind, data, pos, namespaces, variables):
val = self.expr(kind, data, pos, namespaces, variables)
return as_float(val)
def __repr__(self):
return 'number(%r)' % self.expr
class RoundFunction(Function):
"""The `round` function, which returns the nearest integer number for the
given number.
"""
__slots__ = ['number']
def __init__(self, number):
self.number = number
def __call__(self, kind, data, pos, namespaces, variables):
number = self.number(kind, data, pos, namespaces, variables)
return round(as_float(number))
def __repr__(self):
return 'round(%r)' % self.number
class StartsWithFunction(Function):
"""The `starts-with` function that returns whether one string starts with
a given substring.
"""
__slots__ = ['string1', 'string2']
def __init__(self, string1, string2):
self.string1 = string1
self.string2 = string2
def __call__(self, kind, data, pos, namespaces, variables):
string1 = self.string1(kind, data, pos, namespaces, variables)
string2 = self.string2(kind, data, pos, namespaces, variables)
return as_string(string1).startswith(as_string(string2))
def __repr__(self):
return 'starts-with(%r, %r)' % (self.string1, self.string2)
class StringLengthFunction(Function):
"""The `string-length` function that returns the length of the given
string.
"""
__slots__ = ['expr']
def __init__(self, expr):
self.expr = expr
def __call__(self, kind, data, pos, namespaces, variables):
string = self.expr(kind, data, pos, namespaces, variables)
return len(as_string(string))
def __repr__(self):
return 'string-length(%r)' % self.expr
class SubstringFunction(Function):
"""The `substring` function that returns the part of a string that starts
at the given offset, and optionally limited to the given length.
"""
__slots__ = ['string', 'start', 'length']
def __init__(self, string, start, length=None):
self.string = string
self.start = start
self.length = length
def __call__(self, kind, data, pos, namespaces, variables):
string = self.string(kind, data, pos, namespaces, variables)
start = self.start(kind, data, pos, namespaces, variables)
length = 0
if self.length is not None:
length = self.length(kind, data, pos, namespaces, variables)
return string[as_long(start):len(as_string(string)) - as_long(length)]
def __repr__(self):
if self.length is not None:
return 'substring(%r, %r, %r)' % (self.string, self.start,
self.length)
else:
return 'substring(%r, %r)' % (self.string, self.start)
class SubstringAfterFunction(Function):
"""The `substring-after` function that returns the part of a string that
is found after the given substring.
"""
__slots__ = ['string1', 'string2']
def __init__(self, string1, string2):
self.string1 = string1
self.string2 = string2
def __call__(self, kind, data, pos, namespaces, variables):
string1 = as_string(self.string1(kind, data, pos, namespaces, variables))
string2 = as_string(self.string2(kind, data, pos, namespaces, variables))
index = string1.find(string2)
if index >= 0:
return string1[index + len(string2):]
return ''
def __repr__(self):
return 'substring-after(%r, %r)' % (self.string1, self.string2)
class SubstringBeforeFunction(Function):
"""The `substring-before` function that returns the part of a string that
is found before the given substring.
"""
__slots__ = ['string1', 'string2']
def __init__(self, string1, string2):
self.string1 = string1
self.string2 = string2
def __call__(self, kind, data, pos, namespaces, variables):
string1 = as_string(self.string1(kind, data, pos, namespaces, variables))
string2 = as_string(self.string2(kind, data, pos, namespaces, variables))
index = string1.find(string2)
if index >= 0:
return string1[:index]
return ''
def __repr__(self):
return 'substring-after(%r, %r)' % (self.string1, self.string2)
class TranslateFunction(Function):
"""The `translate` function that translates a set of characters in a
string to target set of characters.
"""
__slots__ = ['string', 'fromchars', 'tochars']
def __init__(self, string, fromchars, tochars):
self.string = string
self.fromchars = fromchars
self.tochars = tochars
def __call__(self, kind, data, pos, namespaces, variables):
string = as_string(self.string(kind, data, pos, namespaces, variables))
fromchars = as_string(self.fromchars(kind, data, pos, namespaces, variables))
tochars = as_string(self.tochars(kind, data, pos, namespaces, variables))
table = dict(zip([ord(c) for c in fromchars],
[ord(c) for c in tochars]))
return string.translate(table)
def __repr__(self):
return 'translate(%r, %r, %r)' % (self.string, self.fromchars,
self.tochars)
class TrueFunction(Function):
"""The `true` function, which always returns the boolean `true` value."""
__slots__ = []
def __call__(self, kind, data, pos, namespaces, variables):
return True
def __repr__(self):
return 'true()'
_function_map = {'boolean': BooleanFunction, 'ceiling': CeilingFunction,
'concat': ConcatFunction, 'contains': ContainsFunction,
'matches': MatchesFunction, 'false': FalseFunction, 'floor':
FloorFunction, 'local-name': LocalNameFunction, 'name':
NameFunction, 'namespace-uri': NamespaceUriFunction,
'normalize-space': NormalizeSpaceFunction, 'not': NotFunction,
'number': NumberFunction, 'round': RoundFunction,
'starts-with': StartsWithFunction, 'string-length':
StringLengthFunction, 'substring': SubstringFunction,
'substring-after': SubstringAfterFunction, 'substring-before':
SubstringBeforeFunction, 'translate': TranslateFunction,
'true': TrueFunction}
# Literals & Variables
class Literal(object):
"""Abstract base class for literal nodes."""
class StringLiteral(Literal):
"""A string literal node."""
__slots__ = ['text']
def __init__(self, text):
self.text = text
def __call__(self, kind, data, pos, namespaces, variables):
return self.text
def __repr__(self):
return '"%s"' % self.text
class NumberLiteral(Literal):
"""A number literal node."""
__slots__ = ['number']
def __init__(self, number):
self.number = number
def __call__(self, kind, data, pos, namespaces, variables):
return self.number
def __repr__(self):
return str(self.number)
class VariableReference(Literal):
"""A variable reference node."""
__slots__ = ['name']
def __init__(self, name):
self.name = name
def __call__(self, kind, data, pos, namespaces, variables):
return variables.get(self.name)
def __repr__(self):
return str(self.name)
# Operators
class AndOperator(object):
"""The boolean operator `and`."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = as_bool(self.lval(kind, data, pos, namespaces, variables))
if not lval:
return False
rval = self.rval(kind, data, pos, namespaces, variables)
return as_bool(rval)
def __repr__(self):
return '%s and %s' % (self.lval, self.rval)
class EqualsOperator(object):
"""The equality operator `=`."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = as_scalar(self.lval(kind, data, pos, namespaces, variables))
rval = as_scalar(self.rval(kind, data, pos, namespaces, variables))
return lval == rval
def __repr__(self):
return '%s=%s' % (self.lval, self.rval)
class NotEqualsOperator(object):
"""The equality operator `!=`."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = as_scalar(self.lval(kind, data, pos, namespaces, variables))
rval = as_scalar(self.rval(kind, data, pos, namespaces, variables))
return lval != rval
def __repr__(self):
return '%s!=%s' % (self.lval, self.rval)
class OrOperator(object):
"""The boolean operator `or`."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = as_bool(self.lval(kind, data, pos, namespaces, variables))
if lval:
return True
rval = self.rval(kind, data, pos, namespaces, variables)
return as_bool(rval)
def __repr__(self):
return '%s or %s' % (self.lval, self.rval)
class GreaterThanOperator(object):
"""The relational operator `>` (greater than)."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = self.lval(kind, data, pos, namespaces, variables)
rval = self.rval(kind, data, pos, namespaces, variables)
return as_float(lval) > as_float(rval)
def __repr__(self):
return '%s>%s' % (self.lval, self.rval)
class GreaterThanOrEqualOperator(object):
"""The relational operator `>=` (greater than or equal)."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = self.lval(kind, data, pos, namespaces, variables)
rval = self.rval(kind, data, pos, namespaces, variables)
return as_float(lval) >= as_float(rval)
def __repr__(self):
return '%s>=%s' % (self.lval, self.rval)
class LessThanOperator(object):
"""The relational operator `<` (less than)."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = self.lval(kind, data, pos, namespaces, variables)
rval = self.rval(kind, data, pos, namespaces, variables)
return as_float(lval) < as_float(rval)
def __repr__(self):
return '%s<%s' % (self.lval, self.rval)
class LessThanOrEqualOperator(object):
"""The relational operator `<=` (less than or equal)."""
__slots__ = ['lval', 'rval']
def __init__(self, lval, rval):
self.lval = lval
self.rval = rval
def __call__(self, kind, data, pos, namespaces, variables):
lval = self.lval(kind, data, pos, namespaces, variables)
rval = self.rval(kind, data, pos, namespaces, variables)
return as_float(lval) <= as_float(rval)
def __repr__(self):
return '%s<=%s' % (self.lval, self.rval)
_operator_map = {'=': EqualsOperator, '!=': NotEqualsOperator,
'>': GreaterThanOperator, '>=': GreaterThanOrEqualOperator,
'<': LessThanOperator, '>=': LessThanOrEqualOperator}
_DOTSLASHSLASH = (DESCENDANT_OR_SELF, PrincipalTypeTest(None), ())
_DOTSLASH = (SELF, PrincipalTypeTest(None), ())