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# -*- coding: utf-8 -*-
#
# python-json-pointer - An implementation of the JSON Pointer syntax
# https://github.com/stefankoegl/python-json-pointer
#
# Copyright (c) 2011 Stefan Kögl <stefan@skoegl.net>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# 3. The name of the author may not be used to endorse or promote products
# derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
""" Identify specific nodes in a JSON document according to
http://tools.ietf.org/html/draft-pbryan-zyp-json-pointer-00 """
# Will be parsed by setup.py to determine package metadata
__author__ = 'Stefan Kögl <stefan@skoegl.net>'
__version__ = '0.1'
__website__ = 'https://github.com/stefankoegl/python-json-pointer'
__license__ = 'Modified BSD License'
import urllib
class JsonPointerException(Exception):
pass
_nothing = object()
def resolve_pointer(doc, pointer, default=_nothing):
"""
Resolves pointer against doc and returns the referenced object
>>> obj = {"foo": {"anArray": [ {"prop": 44}], "another prop": {"baz": "A string" }}}
>>> resolve_pointer(obj, '/') == obj
True
>>> resolve_pointer(obj, '/foo') == obj['foo']
True
>>> resolve_pointer(obj, '/foo/another%20prop') == obj['foo']['another prop']
True
>>> resolve_pointer(obj, '/foo/another%20prop/baz') == obj['foo']['another prop']['baz']
True
>>> resolve_pointer(obj, '/foo/anArray/0') == obj['foo']['anArray'][0]
True
>>> resolve_pointer(obj, '/some/path', None) == None
True
"""
pointer = JsonPointer(pointer)
return pointer.resolve(doc, default)
class JsonPointer(object):
""" A JSON Pointer that can reference parts of an JSON document """
def __init__(self, pointer):
parts = pointer.split('/')
if parts.pop(0) != '':
raise JsonPointerException('location must starts with /')
self.parts = map(urllib.unquote, parts)
def resolve(self, doc, default=_nothing):
"""Resolves the pointer against doc and returns the referenced object"""
for part in self.parts:
try:
doc = self.walk(doc, part)
except JsonPointerException:
if default is _nothing:
raise
else:
return default
return doc
def walk(self, doc, part):
""" Walks one step in doc and returns the referenced part """
if not part:
return doc
# Its not clear if a location "1" should be considered as 1 or "1"
# We prefer the integer-variant if possible
part_variants = self._try_parse(part) + [part]
for variant in part_variants:
try:
return doc[variant]
except:
continue
raise JsonPointerException("'%s' not found in %s" % (part, doc))
@staticmethod
def _try_parse(val, cls=int):
try:
return [cls(val)]
except:
return []
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