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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 (RFC 6901) """
- from __future__ import unicode_literals
- # Will be parsed by setup.py to determine package metadata
- __author__ = 'Stefan Kögl <stefan@skoegl.net>'
- __version__ = '2.1'
- __website__ = 'https://github.com/stefankoegl/python-json-pointer'
- __license__ = 'Modified BSD License'
- try:
- from itertools import izip
- str = unicode
- except ImportError: # Python 3
- izip = zip
- try:
- from collections.abc import Mapping, Sequence
- except ImportError: # Python 3
- from collections import Mapping, Sequence
- from itertools import tee
- import re
- import copy
- _nothing = object()
- def set_pointer(doc, pointer, value, inplace=True):
- """Resolves pointer against doc and sets the value of the target within doc.
- With inplace set to true, doc is modified as long as pointer is not the
- root.
- >>> obj = {'foo': {'anArray': [ {'prop': 44}], 'another prop': {'baz': 'A string' }}}
- >>> set_pointer(obj, '/foo/anArray/0/prop', 55) == \
- {'foo': {'another prop': {'baz': 'A string'}, 'anArray': [{'prop': 55}]}}
- True
- >>> set_pointer(obj, '/foo/yet another prop', 'added prop') == \
- {'foo': {'another prop': {'baz': 'A string'}, 'yet another prop': 'added prop', 'anArray': [{'prop': 55}]}}
- True
- >>> obj = {'foo': {}}
- >>> set_pointer(obj, '/foo/a%20b', 'x') == \
- {'foo': {'a%20b': 'x' }}
- True
- """
- pointer = JsonPointer(pointer)
- return pointer.set(doc, value, inplace)
- 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' }}, 'a%20b': 1, 'c d': 2}
- >>> resolve_pointer(obj, '') == obj
- True
- >>> resolve_pointer(obj, '/foo') == obj['foo']
- True
- >>> resolve_pointer(obj, '/foo/another prop') == obj['foo']['another prop']
- True
- >>> resolve_pointer(obj, '/foo/another prop/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
- >>> resolve_pointer(obj, '/a b', None) == None
- True
- >>> resolve_pointer(obj, '/a%20b') == 1
- True
- >>> resolve_pointer(obj, '/c d') == 2
- True
- >>> resolve_pointer(obj, '/c%20d', None) == None
- True
- """
- pointer = JsonPointer(pointer)
- return pointer.resolve(doc, default)
- def pairwise(iterable):
- """ Transforms a list to a list of tuples of adjacent items
- s -> (s0,s1), (s1,s2), (s2, s3), ...
- >>> list(pairwise([]))
- []
- >>> list(pairwise([1]))
- []
- >>> list(pairwise([1, 2, 3, 4]))
- [(1, 2), (2, 3), (3, 4)]
- """
- a, b = tee(iterable)
- for _ in b:
- break
- return izip(a, b)
- class JsonPointerException(Exception):
- pass
- class EndOfList(object):
- """Result of accessing element "-" of a list"""
- def __init__(self, list_):
- self.list_ = list_
- def __repr__(self):
- return '{cls}({lst})'.format(cls=self.__class__.__name__,
- lst=repr(self.list_))
- class JsonPointer(object):
- """A JSON Pointer that can reference parts of a JSON document"""
- # Array indices must not contain:
- # leading zeros, signs, spaces, decimals, etc
- _RE_ARRAY_INDEX = re.compile('0|[1-9][0-9]*$')
- _RE_INVALID_ESCAPE = re.compile('(~[^01]|~$)')
- def __init__(self, pointer):
- # validate escapes
- invalid_escape = self._RE_INVALID_ESCAPE.search(pointer)
- if invalid_escape:
- raise JsonPointerException('Found invalid escape {}'.format(
- invalid_escape.group()))
- parts = pointer.split('/')
- if parts.pop(0) != '':
- raise JsonPointerException('Location must start with /')
- parts = [unescape(part) for part in parts]
- self.parts = parts
- def to_last(self, doc):
- """Resolves ptr until the last step, returns (sub-doc, last-step)"""
- if not self.parts:
- return doc, None
- for part in self.parts[:-1]:
- doc = self.walk(doc, part)
- return doc, self.get_part(doc, self.parts[-1])
- 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
- get = resolve
- def set(self, doc, value, inplace=True):
- """Resolve the pointer against the doc and replace the target with value."""
- if len(self.parts) == 0:
- if inplace:
- raise JsonPointerException('Cannot set root in place')
- return value
- if not inplace:
- doc = copy.deepcopy(doc)
- (parent, part) = self.to_last(doc)
- parent[part] = value
- return doc
- def get_part(self, doc, part):
- """Returns the next step in the correct type"""
- if isinstance(doc, Mapping):
- return part
- elif isinstance(doc, Sequence):
- if part == '-':
- return part
- if not self._RE_ARRAY_INDEX.match(str(part)):
- raise JsonPointerException("'%s' is not a valid sequence index" % part)
- return int(part)
- elif hasattr(doc, '__getitem__'):
- # Allow indexing via ducktyping
- # if the target has defined __getitem__
- return part
- else:
- raise JsonPointerException("Document '%s' does not support indexing, "
- "must be mapping/sequence or support __getitem__" % type(doc))
- def walk(self, doc, part):
- """ Walks one step in doc and returns the referenced part """
- part = self.get_part(doc, part)
- assert hasattr(doc, '__getitem__'), "invalid document type %s" % (type(doc),)
- if isinstance(doc, Sequence):
- if part == '-':
- return EndOfList(doc)
- try:
- return doc[part]
- except IndexError:
- raise JsonPointerException("index '%s' is out of bounds" % (part, ))
- # Else the object is a mapping or supports __getitem__(so assume custom indexing)
- try:
- return doc[part]
- except KeyError:
- raise JsonPointerException("member '%s' not found in %s" % (part, doc))
- def contains(self, ptr):
- """ Returns True if self contains the given ptr """
- return self.parts[:len(ptr.parts)] == ptr.parts
- def __contains__(self, item):
- """ Returns True if self contains the given ptr """
- return self.contains(item)
- @property
- def path(self):
- """Returns the string representation of the pointer
- >>> ptr = JsonPointer('/~0/0/~1').path == '/~0/0/~1'
- """
- parts = [escape(part) for part in self.parts]
- return ''.join('/' + part for part in parts)
- def __eq__(self, other):
- """Compares a pointer to another object
- Pointers can be compared by comparing their strings (or splitted
- strings), because no two different parts can point to the same
- structure in an object (eg no different number representations)
- """
- if not isinstance(other, JsonPointer):
- return False
- return self.parts == other.parts
- def __hash__(self):
- return hash(tuple(self.parts))
- @classmethod
- def from_parts(cls, parts):
- """Constructs a JsonPointer from a list of (unescaped) paths
- >>> JsonPointer.from_parts(['a', '~', '/', 0]).path == '/a/~0/~1/0'
- True
- """
- parts = [escape(str(part)) for part in parts]
- ptr = cls(''.join('/' + part for part in parts))
- return ptr
- def escape(s):
- return s.replace('~', '~0').replace('/', '~1')
- def unescape(s):
- return s.replace('~1', '/').replace('~0', '~')
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