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# -*- coding: utf-8 -*-
#
# python-json-patch - An implementation of the JSON Patch format
# https://github.com/stefankoegl/python-json-patch
#
# Copyright (c) 2011 Stefan Kögl <[email protected]>
# 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.
#
""" Apply JSON-Patches (RFC 6902) """
from __future__ import unicode_literals
import collections
import copy
import functools
import json
import sys
from jsonpointer import JsonPointer, JsonPointerException
_ST_ADD = 0
_ST_REMOVE = 1
try:
from collections.abc import MutableMapping, MutableSequence
except ImportError:
from collections import MutableMapping, MutableSequence
str = unicode
# Will be parsed by setup.py to determine package metadata
__author__ = 'Stefan Kögl <[email protected]>'
__version__ = '1.22'
__website__ = 'https://github.com/stefankoegl/python-json-patch'
__license__ = 'Modified BSD License'
# pylint: disable=E0611,W0404
if sys.version_info >= (3, 0):
basestring = (bytes, str) # pylint: disable=C0103,W0622
class JsonPatchException(Exception):
"""Base Json Patch exception"""
class InvalidJsonPatch(JsonPatchException):
""" Raised if an invalid JSON Patch is created """
class JsonPatchConflict(JsonPatchException):
"""Raised if patch could not be applied due to conflict situation such as:
- attempt to add object key then it already exists;
- attempt to operate with nonexistence object key;
- attempt to insert value to array at position beyond of it size;
- etc.
"""
class JsonPatchTestFailed(JsonPatchException, AssertionError):
""" A Test operation failed """
def multidict(ordered_pairs):
"""Convert duplicate keys values to lists."""
# read all values into lists
mdict = collections.defaultdict(list)
for key, value in ordered_pairs:
mdict[key].append(value)
return dict(
# unpack lists that have only 1 item
(key, values[0] if len(values) == 1 else values)
for key, values in mdict.items()
)
# The "object_pairs_hook" parameter is used to handle duplicate keys when
# loading a JSON object.
_jsonloads = functools.partial(json.loads, object_pairs_hook=multidict)
def apply_patch(doc, patch, in_place=False):
"""Apply list of patches to specified json document.
:param doc: Document object.
:type doc: dict
:param patch: JSON patch as list of dicts or raw JSON-encoded string.
:type patch: list or str
:param in_place: While :const:`True` patch will modify target document.
By default patch will be applied to document copy.
:type in_place: bool
:return: Patched document object.
:rtype: dict
>>> doc = {'foo': 'bar'}
>>> patch = [{'op': 'add', 'path': '/baz', 'value': 'qux'}]
>>> other = apply_patch(doc, patch)
>>> doc is not other
True
>>> other == {'foo': 'bar', 'baz': 'qux'}
True
>>> patch = [{'op': 'add', 'path': '/baz', 'value': 'qux'}]
>>> apply_patch(doc, patch, in_place=True) == {'foo': 'bar', 'baz': 'qux'}
True
>>> doc == other
True
"""
if isinstance(patch, basestring):
patch = JsonPatch.from_string(patch)
else:
patch = JsonPatch(patch)
return patch.apply(doc, in_place)
def make_patch(src, dst):
"""Generates patch by comparing of two document objects. Actually is
a proxy to :meth:`JsonPatch.from_diff` method.
:param src: Data source document object.
:type src: dict
:param dst: Data source document object.
:type dst: dict
>>> src = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}
>>> dst = {'baz': 'qux', 'numbers': [1, 4, 7]}
>>> patch = make_patch(src, dst)
>>> new = patch.apply(src)
>>> new == dst
True
"""
return JsonPatch.from_diff(src, dst)
class JsonPatch(object):
"""A JSON Patch is a list of Patch Operations.
>>> patch = JsonPatch([
... {'op': 'add', 'path': '/foo', 'value': 'bar'},
... {'op': 'add', 'path': '/baz', 'value': [1, 2, 3]},
... {'op': 'remove', 'path': '/baz/1'},
... {'op': 'test', 'path': '/baz', 'value': [1, 3]},
... {'op': 'replace', 'path': '/baz/0', 'value': 42},
... {'op': 'remove', 'path': '/baz/1'},
... ])
>>> doc = {}
>>> result = patch.apply(doc)
>>> expected = {'foo': 'bar', 'baz': [42]}
>>> result == expected
True
JsonPatch object is iterable, so you could easily access to each patch
statement in loop:
>>> lpatch = list(patch)
>>> expected = {'op': 'add', 'path': '/foo', 'value': 'bar'}
>>> lpatch[0] == expected
True
>>> lpatch == patch.patch
True
Also JsonPatch could be converted directly to :class:`bool` if it contains
any operation statements:
>>> bool(patch)
True
>>> bool(JsonPatch([]))
False
This behavior is very handy with :func:`make_patch` to write more readable
code:
>>> old = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}
>>> new = {'baz': 'qux', 'numbers': [1, 4, 7]}
>>> patch = make_patch(old, new)
>>> if patch:
... # document have changed, do something useful
... patch.apply(old) #doctest: +ELLIPSIS
{...}
"""
def __init__(self, patch):
self.patch = patch
self.operations = {
'remove': RemoveOperation,
'add': AddOperation,
'replace': ReplaceOperation,
'move': MoveOperation,
'test': TestOperation,
'copy': CopyOperation,
}
def __str__(self):
"""str(self) -> self.to_string()"""
return self.to_string()
def __bool__(self):
return bool(self.patch)
__nonzero__ = __bool__
def __iter__(self):
return iter(self.patch)
def __hash__(self):
return hash(tuple(self._ops))
def __eq__(self, other):
if not isinstance(other, JsonPatch):
return False
return self._ops == other._ops
def __ne__(self, other):
return not(self == other)
@classmethod
def from_string(cls, patch_str):
"""Creates JsonPatch instance from string source.
:param patch_str: JSON patch as raw string.
:type patch_str: str
:return: :class:`JsonPatch` instance.
"""
patch = _jsonloads(patch_str)
return cls(patch)
@classmethod
def from_diff(cls, src, dst, optimization=True):
"""Creates JsonPatch instance based on comparing of two document
objects. Json patch would be created for `src` argument against `dst`
one.
:param src: Data source document object.
:type src: dict
:param dst: Data source document object.
:type dst: dict
:return: :class:`JsonPatch` instance.
>>> src = {'foo': 'bar', 'numbers': [1, 3, 4, 8]}
>>> dst = {'baz': 'qux', 'numbers': [1, 4, 7]}
>>> patch = JsonPatch.from_diff(src, dst)
>>> new = patch.apply(src)
>>> new == dst
True
"""
builder = DiffBuilder()
builder._compare_values('', None, src, dst)
ops = list(builder.execute())
return cls(ops)
def to_string(self):
"""Returns patch set as JSON string."""
return json.dumps(self.patch)
@property
def _ops(self):
return tuple(map(self._get_operation, self.patch))
def apply(self, obj, in_place=False):
"""Applies the patch to given object.
:param obj: Document object.
:type obj: dict
:param in_place: Tweaks way how patch would be applied - directly to
specified `obj` or to his copy.
:type in_place: bool
:return: Modified `obj`.
"""
if not in_place:
obj = copy.deepcopy(obj)
for operation in self._ops:
obj = operation.apply(obj)
return obj
def _get_operation(self, operation):
if 'op' not in operation:
raise InvalidJsonPatch("Operation does not contain 'op' member")
op = operation['op']
if not isinstance(op, basestring):
raise InvalidJsonPatch("Operation must be a string")
if op not in self.operations:
raise InvalidJsonPatch("Unknown operation {0!r}".format(op))
cls = self.operations[op]
return cls(operation)
class PatchOperation(object):
"""A single operation inside a JSON Patch."""
def __init__(self, operation):
if isinstance(operation['path'], JsonPointer):
self.location = operation['path'].path
self.pointer = operation['path']
else:
self.location = operation['path']
self.pointer = JsonPointer(self.location)
self.operation = operation
def apply(self, obj):
"""Abstract method that applies patch operation to specified object."""
raise NotImplementedError('should implement patch operation.')
def __hash__(self):
return hash(frozenset(self.operation.items()))
def __eq__(self, other):
if not isinstance(other, PatchOperation):
return False
return self.operation == other.operation
def __ne__(self, other):
return not(self == other)
@property
def path(self):
return '/'.join(self.pointer.parts[:-1])
@property
def key(self):
try:
return int(self.pointer.parts[-1])
except ValueError:
return self.pointer.parts[-1]
@key.setter
def key(self, value):
self.pointer.parts[-1] = str(value)
self.location = self.pointer.path
self.operation['path'] = self.location
class RemoveOperation(PatchOperation):
"""Removes an object property or an array element."""
def apply(self, obj):
subobj, part = self.pointer.to_last(obj)
try:
del subobj[part]
except (KeyError, IndexError) as ex:
msg = "can't remove non-existent object '{0}'".format(part)
raise JsonPatchConflict(msg)
return obj
def _on_undo_remove(self, path, key):
if self.path == path:
if self.key >= key:
self.key += 1
else:
key -= 1
return key
def _on_undo_add(self, path, key):
if self.path == path:
if self.key > key:
self.key -= 1
else:
key -= 1
return key
class AddOperation(PatchOperation):
"""Adds an object property or an array element."""
def apply(self, obj):
try:
value = self.operation["value"]
except KeyError as ex:
raise InvalidJsonPatch(
"The operation does not contain a 'value' member")
subobj, part = self.pointer.to_last(obj)
if isinstance(subobj, MutableSequence):
if part == '-':
subobj.append(value) # pylint: disable=E1103
elif part > len(subobj) or part < 0:
raise JsonPatchConflict("can't insert outside of list")
else:
subobj.insert(part, value) # pylint: disable=E1103
elif isinstance(subobj, MutableMapping):
if part is None:
obj = value # we're replacing the root
else:
subobj[part] = value
else:
if part is None:
raise TypeError("invalid document type {0}".format(type(subobj)))
else:
raise JsonPatchConflict("unable to fully resolve json pointer {0}, part {1}".format(self.location, part))
return obj
def _on_undo_remove(self, path, key):
if self.path == path:
if self.key > key:
self.key += 1
else:
key += 1
return key
def _on_undo_add(self, path, key):
if self.path == path:
if self.key > key:
self.key -= 1
else:
key += 1
return key
class ReplaceOperation(PatchOperation):
"""Replaces an object property or an array element by new value."""
def apply(self, obj):
try:
value = self.operation["value"]
except KeyError as ex:
raise InvalidJsonPatch(
"The operation does not contain a 'value' member")
subobj, part = self.pointer.to_last(obj)
if part is None:
return value
if isinstance(subobj, MutableSequence):
if part > len(subobj) or part < 0:
raise JsonPatchConflict("can't replace outside of list")
elif isinstance(subobj, MutableMapping):
if part not in subobj:
msg = "can't replace non-existent object '{0}'".format(part)
raise JsonPatchConflict(msg)
else:
if part is None:
raise TypeError("invalid document type {0}".format(type(subobj)))
else:
raise JsonPatchConflict("unable to fully resolve json pointer {0}, part {1}".format(self.location, part))
subobj[part] = value
return obj
def _on_undo_remove(self, path, key):
return key
def _on_undo_add(self, path, key):
return key
class MoveOperation(PatchOperation):
"""Moves an object property or an array element to new location."""
def apply(self, obj):
try:
if isinstance(self.operation['from'], JsonPointer):
from_ptr = self.operation['from']
else:
from_ptr = JsonPointer(self.operation['from'])
except KeyError as ex:
raise InvalidJsonPatch(
"The operation does not contain a 'from' member")
subobj, part = from_ptr.to_last(obj)
try:
value = subobj[part]
except (KeyError, IndexError) as ex:
raise JsonPatchConflict(str(ex))
# If source and target are equal, this is a no-op
if self.pointer == from_ptr:
return obj
if isinstance(subobj, MutableMapping) and \
self.pointer.contains(from_ptr):
raise JsonPatchConflict('Cannot move values into its own children')
obj = RemoveOperation({
'op': 'remove',
'path': self.operation['from']
}).apply(obj)
obj = AddOperation({
'op': 'add',
'path': self.location,
'value': value
}).apply(obj)
return obj
@property
def from_path(self):
from_ptr = JsonPointer(self.operation['from'])
return '/'.join(from_ptr.parts[:-1])
@property
def from_key(self):
from_ptr = JsonPointer(self.operation['from'])
try:
return int(from_ptr.parts[-1])
except TypeError:
return from_ptr.parts[-1]
@from_key.setter
def from_key(self, value):
from_ptr = JsonPointer(self.operation['from'])
from_ptr.parts[-1] = str(value)
self.operation['from'] = from_ptr.path
def _on_undo_remove(self, path, key):
if self.from_path == path:
if self.from_key >= key:
self.from_key += 1
else:
key -= 1
if self.path == path:
if self.key > key:
self.key += 1
else:
key += 1
return key
def _on_undo_add(self, path, key):
if self.from_path == path:
if self.from_key > key:
self.from_key -= 1
else:
key -= 1
if self.path == path:
if self.key > key:
self.key -= 1
else:
key += 1
return key
class TestOperation(PatchOperation):
"""Test value by specified location."""
def apply(self, obj):
try:
subobj, part = self.pointer.to_last(obj)
if part is None:
val = subobj
else:
val = self.pointer.walk(subobj, part)
except JsonPointerException as ex:
raise JsonPatchTestFailed(str(ex))
try:
value = self.operation['value']
except KeyError as ex:
raise InvalidJsonPatch(
"The operation does not contain a 'value' member")
if val != value:
msg = '{0} ({1}) is not equal to tested value {2} ({3})'
raise JsonPatchTestFailed(msg.format(val, type(val),
value, type(value)))
return obj
class CopyOperation(PatchOperation):
""" Copies an object property or an array element to a new location """
def apply(self, obj):
try:
from_ptr = JsonPointer(self.operation['from'])
except KeyError as ex:
raise InvalidJsonPatch(
"The operation does not contain a 'from' member")
subobj, part = from_ptr.to_last(obj)
try:
value = copy.deepcopy(subobj[part])
except (KeyError, IndexError) as ex:
raise JsonPatchConflict(str(ex))
obj = AddOperation({
'op': 'add',
'path': self.location,
'value': value
}).apply(obj)
return obj
class DiffBuilder(object):
def __init__(self):
self.index_storage = [{}, {}]
self.index_storage2 = [[], []]
self.__root = root = []
root[:] = [root, root, None]
def store_index(self, value, index, st):
try:
storage = self.index_storage[st]
stored = storage.get(value)
if stored is None:
storage[value] = [index]
else:
storage[value].append(index)
except TypeError:
self.index_storage2[st].append((value, index))
def take_index(self, value, st):
try:
stored = self.index_storage[st].get(value)
if stored:
return stored.pop()
except TypeError:
storage = self.index_storage2[st]
for i in range(len(storage)-1, -1, -1):
if storage[i][0] == value:
return storage.pop(i)[1]
def insert(self, op):
root = self.__root
last = root[0]
last[1] = root[0] = [last, root, op]
return root[0]
def remove(self, index):
link_prev, link_next, _ = index
link_prev[1] = link_next
link_next[0] = link_prev
index[:] = []
def iter_from(self, start):
root = self.__root
curr = start[1]
while curr is not root:
yield curr[2]
curr = curr[1]
def __iter__(self):
root = self.__root
curr = root[1]
while curr is not root:
yield curr[2]
curr = curr[1]
def execute(self):
root = self.__root
curr = root[1]
while curr is not root:
if curr[1] is not root:
op_first, op_second = curr[2], curr[1][2]
if op_first.location == op_second.location and \
type(op_first) == RemoveOperation and \
type(op_second) == AddOperation:
yield ReplaceOperation({
'op': 'replace',
'path': op_second.location,
'value': op_second.operation['value'],
}).operation
curr = curr[1][1]
continue
yield curr[2].operation
curr = curr[1]
def _item_added(self, path, key, item):
index = self.take_index(item, _ST_REMOVE)
if index is not None:
op = index[2]
if type(op.key) == int:
for v in self.iter_from(index):
op.key = v._on_undo_remove(op.path, op.key)
self.remove(index)
if op.location != _path_join(path, key):
new_op = MoveOperation({
'op': 'move',
'from': op.location,
'path': _path_join(path, key),
})
self.insert(new_op)
else:
new_op = AddOperation({
'op': 'add',
'path': _path_join(path, key),
'value': item,
})
new_index = self.insert(new_op)
self.store_index(item, new_index, _ST_ADD)
def _item_removed(self, path, key, item):
new_op = RemoveOperation({
'op': 'remove',
'path': _path_join(path, key),
})
index = self.take_index(item, _ST_ADD)
new_index = self.insert(new_op)
if index is not None:
op = index[2]
if type(op.key) == int:
for v in self.iter_from(index):
op.key = v._on_undo_add(op.path, op.key)
self.remove(index)
if new_op.location != op.location:
new_op = MoveOperation({
'op': 'move',
'from': new_op.location,
'path': op.location,
})
new_index[2] = new_op
else:
self.remove(new_index)
else:
self.store_index(item, new_index, _ST_REMOVE)
def _item_replaced(self, path, key, item):
self.insert(ReplaceOperation({
'op': 'replace',
'path': _path_join(path, key),
'value': item,
}))
def _compare_dicts(self, path, src, dst):
src_keys = set(src.keys())
dst_keys = set(dst.keys())
added_keys = dst_keys - src_keys
removed_keys = src_keys - dst_keys
for key in removed_keys:
self._item_removed(path, str(key), src[key])
for key in added_keys:
self._item_added(path, str(key), dst[key])
for key in src_keys & dst_keys:
self._compare_values(path, key, src[key], dst[key])
def _compare_lists(self, path, src, dst):
len_src, len_dst = len(src), len(dst)
max_len = max(len_src, len_dst)
min_len = min(len_src, len_dst)
for key in range(max_len):
if key < min_len:
old, new = src[key], dst[key]
if old == new:
continue
elif isinstance(old, MutableMapping) and \
isinstance(new, MutableMapping):
self._compare_dicts(_path_join(path, key), old, new)
elif isinstance(old, MutableSequence) and \
isinstance(new, MutableSequence):
self._compare_lists(_path_join(path, key), old, new)
else:
self._item_removed(path, key, old)
self._item_added(path, key, new)
elif len_src > len_dst:
self._item_removed(path, len_dst, src[key])
else:
self._item_added(path, key, dst[key])
def _compare_values(self, path, key, src, dst):
if src == dst:
return
elif isinstance(src, MutableMapping) and \
isinstance(dst, MutableMapping):
self._compare_dicts(_path_join(path, key), src, dst)
elif isinstance(src, MutableSequence) and \
isinstance(dst, MutableSequence):
self._compare_lists(_path_join(path, key), src, dst)
else:
self._item_replaced(path, key, dst)
def _path_join(path, key):
if key is None:
return path
return path + '/' + str(key).replace('~', '~0').replace('/', '~1')
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