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import copy
from abc import ABC, abstractmethod # pylint: disable=[no-name-in-module]
from typing import Any, List, Literal, Optional, Tuple, Union
from knot_resolver.utils.modeling.base_schema import BaseSchema, map_object
from knot_resolver.utils.modeling.json_pointer import json_ptr_resolve
class PatchError(Exception):
pass
class Op(BaseSchema, ABC):
@abstractmethod
def eval(self, fakeroot: Any) -> Any:
"""
modifies the given fakeroot, returns a new one
"""
def _resolve_ptr(self, fakeroot: Any, ptr: str) -> Tuple[Any, Any, Union[str, int, None]]:
# Lookup tree part based on the given JSON pointer
parent, obj, token = json_ptr_resolve(fakeroot["root"], ptr)
# the lookup was on pure data, wrap the results in QueryTree
if parent is None:
parent = fakeroot
token = "root"
assert token is not None
return parent, obj, token
class AddOp(Op):
op: Literal["add"]
path: str
value: Any
def eval(self, fakeroot: Any) -> Any:
parent, _obj, token = self._resolve_ptr(fakeroot, self.path)
if isinstance(parent, dict):
parent[token] = self.value
elif isinstance(parent, list):
if token == "-":
parent.append(self.value)
else:
assert isinstance(token, int)
parent.insert(token, self.value)
else:
assert False, "never happens"
return fakeroot
class RemoveOp(Op):
op: Literal["remove"]
path: str
def eval(self, fakeroot: Any) -> Any:
parent, _obj, token = self._resolve_ptr(fakeroot, self.path)
del parent[token]
return fakeroot
class ReplaceOp(Op):
op: Literal["replace"]
path: str
value: str
def eval(self, fakeroot: Any) -> Any:
parent, obj, token = self._resolve_ptr(fakeroot, self.path)
if obj is None:
raise PatchError("the value you are trying to replace is null")
parent[token] = self.value
return fakeroot
class MoveOp(Op):
op: Literal["move"]
source: str
path: str
def _source(self, source):
if "from" not in source:
raise ValueError("missing property 'from' in 'move' JSON patch operation")
return str(source["from"])
def eval(self, fakeroot: Any) -> Any:
if self.path.startswith(self.source):
raise PatchError("can't move value into itself")
_parent, obj, _token = self._resolve_ptr(fakeroot, self.source)
newobj = copy.deepcopy(obj)
fakeroot = RemoveOp({"op": "remove", "path": self.source}).eval(fakeroot)
fakeroot = AddOp({"path": self.path, "value": newobj, "op": "add"}).eval(fakeroot)
return fakeroot
class CopyOp(Op):
op: Literal["copy"]
source: str
path: str
def _source(self, source):
if "from" not in source:
raise ValueError("missing property 'from' in 'copy' JSON patch operation")
return str(source["from"])
def eval(self, fakeroot: Any) -> Any:
_parent, obj, _token = self._resolve_ptr(fakeroot, self.source)
newobj = copy.deepcopy(obj)
fakeroot = AddOp({"path": self.path, "value": newobj, "op": "add"}).eval(fakeroot)
return fakeroot
class TestOp(Op):
op: Literal["test"]
path: str
value: Any
def eval(self, fakeroot: Any) -> Any:
_parent, obj, _token = self._resolve_ptr(fakeroot, self.path)
if obj != self.value:
raise PatchError("test failed")
return fakeroot
def query(
original: Any, method: Literal["get", "delete", "put", "patch"], ptr: str, payload: Any
) -> Tuple[Any, Optional[Any]]:
########################################
# Prepare data we will be working on
# First of all, we consider the original data to be immutable. So we need to make a copy
# in order to freely mutate them
dataroot = copy.deepcopy(original)
# To simplify referencing the root, create a fake root node
fakeroot = {"root": dataroot}
#########################################
# Handle the actual requested operation
# get = return what the path selector picks
if method == "get":
parent, obj, token = json_ptr_resolve(fakeroot, f"/root{ptr}")
return fakeroot["root"], obj
elif method == "delete":
fakeroot = RemoveOp({"op": "remove", "path": ptr}).eval(fakeroot)
return fakeroot["root"], None
elif method == "put":
parent, obj, token = json_ptr_resolve(fakeroot, f"/root{ptr}")
assert parent is not None # we know this due to the fakeroot
if isinstance(parent, list) and token == "-":
parent.append(payload)
else:
parent[token] = payload
return fakeroot["root"], None
elif method == "patch":
tp = List[Union[AddOp, RemoveOp, MoveOp, CopyOp, TestOp, ReplaceOp]]
transaction: tp = map_object(tp, payload)
for i, op in enumerate(transaction):
try:
fakeroot = op.eval(fakeroot)
except PatchError as e:
raise ValueError(f"json patch transaction failed on step {i}") from e
return fakeroot["root"], None
else:
assert False, "invalid operation, never happens"
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