/edk2/AppPkg/Applications/Python/Python-2.7.2/Lib/xml/etree/ElementPath.py

#

# 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:

            for e in elem:

                yield e

    return select



def prepare_self(next, token):

    def select(context, result):

        for elem in result:

            yield elem

    return select



def prepare_descendant(next, token):

    token = next()

    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:

        token = next()

        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 = int(predicate[0]) - 1

        else:

            if predicate[0] != "last":

                raise SyntaxError("unsupported function")

            if signature == "-()-":

                try:

                    index = int(predicate[2]) - 1

                except ValueError:

                    raise SyntaxError("unsupported expression")

            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

    if path[-1:] == "/":

        path = path + "*" # implicit all (FIXME: keep this?)

    try:

        selector = _cache[path]

    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

        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 first matching object.



def find(elem, path, namespaces=None):

    try:

        return iterfind(elem, path, namespaces).next()

    except StopIteration:

        return 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 = iterfind(elem, path, namespaces).next()

        return elem.text or ""

    except StopIteration:

        return default