dvc/parsing/context.py
from abc import ABC, abstractmethod
from collections import defaultdict
from collections.abc import Mapping, MutableMapping, MutableSequence, Sequence
from contextlib import contextmanager
from copy import deepcopy
from dataclasses import dataclass, field, replace
from typing import Any, Optional, Union
from funcy import identity, lfilter, nullcontext, select
from dvc.exceptions import DvcException
from dvc.log import logger
from dvc.parsing.interpolate import (
get_expression,
get_matches,
is_exact_string,
normalize_key,
recurse,
str_interpolate,
validate_value,
)
logger = logger.getChild(__name__)
SeqOrMap = Union[Sequence, Mapping]
DictStr = dict[str, Any]
class ContextError(DvcException):
pass
class ReservedKeyError(ContextError):
def __init__(self, keys, path=None):
from dvc.utils.humanize import join
self.keys = keys
self.path = path
n = "key" + ("s" if len(keys) > 1 else "")
msg = f"attempted to modify reserved {n} {join(keys)}"
if path:
msg += f" in '{path}'"
super().__init__(msg)
class MergeError(ContextError):
def __init__(self, key, new, into):
self.key = key
to_node = into[key]
if not isinstance(to_node, Node) or not isinstance(new, Node):
super().__init__(f"cannot merge '{key}' as it already exists in {into}")
return
assert isinstance(to_node, Node)
assert isinstance(new, Node)
preexisting = to_node.meta.source
new_src = new.meta.source
path = new.meta.path()
super().__init__(
f"cannot redefine '{path}' from '{new_src}'"
f" as it already exists in '{preexisting}'"
)
class ParamsLoadError(ContextError):
pass
class KeyNotInContext(ContextError, KeyError):
def __init__(self, key: str) -> None:
self.key: str = key
super().__init__(f"Could not find '{key}'")
def __str__(self):
return self.msg
class VarsAlreadyLoaded(ContextError):
pass
def _merge(into, update, overwrite):
for key, val in update.items():
if isinstance(into.get(key), Mapping) and isinstance(val, Mapping):
_merge(into[key], val, overwrite)
else:
if key in into and not overwrite:
raise MergeError(key, val, into)
into[key] = val
assert isinstance(into[key], Node)
def recurse_not_a_node(data: dict):
def func(item):
assert not isinstance(item, Node)
return recurse(func)(data)
@dataclass
class Meta:
source: Optional[str] = None
dpaths: list[str] = field(default_factory=list)
local: bool = True
@staticmethod
def update_path(meta: "Meta", path: Union[str, int]):
dpaths = meta.dpaths[:] + [str(path)]
return replace(meta, dpaths=dpaths)
def __str__(self):
string = self.source or "<local>"
string += ":" + self.path()
return string
def path(self):
return ".".join(self.dpaths)
def _default_meta() -> Meta:
return Meta()
class Node:
meta: Meta
def get_sources(self):
raise NotImplementedError
@property
@abstractmethod
def value(self):
pass
@dataclass
class Value(Node):
_value: Any
meta: Meta = field(compare=False, default_factory=_default_meta, repr=False)
def __repr__(self):
return repr(self._value)
def __str__(self) -> str:
return str(self._value)
def get_sources(self):
return {self.meta.source: self.meta.path()}
@property
def value(self):
return self._value
PRIMITIVES = (int, float, str, bytes, bool)
class Container(Node, ABC):
meta: Meta
data: Union[list, dict]
_key_transform = staticmethod(identity)
def __init__(self, meta=None) -> None:
self.meta = meta or _default_meta()
def _convert(self, key, value):
meta = Meta.update_path(self.meta, key)
return self._convert_with_meta(value, meta)
@staticmethod
def _convert_with_meta(value, meta: Optional[Meta] = None):
if value is None or isinstance(value, PRIMITIVES):
assert meta
return Value(value, meta=meta)
if isinstance(value, Node):
return value
if isinstance(value, (list, dict)):
assert meta
container = CtxDict if isinstance(value, dict) else CtxList
return container(value, meta=meta)
msg = f"Unsupported value of type '{type(value).__name__}' in '{meta}'"
raise TypeError(msg)
def __repr__(self):
return repr(self.data)
def __getitem__(self, key):
return self.data[key]
def __setitem__(self, key, value):
self.data[key] = self._convert(key, value)
def __delitem__(self, key):
del self.data[key]
def __len__(self):
return len(self.data)
def __iter__(self):
return iter(self.data)
def __eq__(self, o):
container = type(self)
if isinstance(o, container):
return o.data == self.data
return container(o) == self
def select(self, key: str):
index, *rems = key.split(sep=".", maxsplit=1)
index = index.strip()
index = self._key_transform(index)
try:
d = self[index]
except LookupError as exc:
raise ValueError(f"Could not find '{index}' in {self.data}") from exc
if not rems:
return d
rem = rems[0]
if not isinstance(d, Container):
raise ValueError( # noqa: TRY004
f"{index} is a primitive value, cannot get '{rem}'"
)
return d.select(rem)
def get_sources(self):
return {}
class CtxList(Container, MutableSequence):
_key_transform = staticmethod(int)
def __init__(self, values: Sequence, meta: Optional[Meta] = None):
super().__init__(meta=meta)
self.data: list = []
self.extend(values)
def insert(self, index: int, value):
self.data.insert(index, self._convert(index, value))
def get_sources(self):
return {self.meta.source: self.meta.path()}
@property
def value(self):
return [node.value for node in self]
def __deepcopy__(self, _):
# optimization: we don't support overriding a list
new = CtxList([])
new.data = self.data[:] # Short-circuiting __setitem__
return new
class CtxDict(Container, MutableMapping):
def __init__(
self,
mapping: Optional[Mapping] = None,
meta: Optional[Meta] = None,
**kwargs,
):
super().__init__(meta=meta)
self.data: dict = {}
if mapping:
self.update(mapping)
self.update(kwargs)
def __setitem__(self, key, value):
if not isinstance(key, str):
# limitation for the interpolation
# ignore other kinds of keys
return
return super().__setitem__(key, value)
def merge_update(self, other, overwrite=False):
_merge(self, other, overwrite=overwrite)
@property
def value(self):
return {key: node.value for key, node in self.items()}
def __deepcopy__(self, _):
new = CtxDict()
for k, v in self.items():
new.data[k] = (
deepcopy(v) if isinstance(v, Container) else v
) # short-circuiting __setitem__
return new
class Context(CtxDict):
def __init__(self, *args, **kwargs):
"""
Top level mutable dict, with some helpers to create context and track
"""
super().__init__(*args, **kwargs)
self._track = False
self._tracked_data: dict[str, dict] = defaultdict(dict)
self.imports = {}
self._reserved_keys = {}
@contextmanager
def track(self):
self._track = True
yield self._tracked_data
self._track = False
self._tracked_data = defaultdict(dict)
def _track_data(self, node):
if not self._track or not isinstance(node, Node):
return
assert isinstance(node, Node)
if node.meta and node.meta.local:
return
for source, keys in node.get_sources().items():
if not source:
continue
params_file = self._tracked_data[source]
keys = [keys] if isinstance(keys, str) else keys
params_file.update(dict.fromkeys(keys, node.value))
def select(self, key: str, unwrap: bool = False):
"""Select the item using key, similar to `__getitem__`
but can track the usage of the data on interpolation
as well and can get from nested data structure by using
"." separated key (eg: "key1.key2.key3")
Args:
key: key to select value from
unwrap: Convert CtxList/CtxDict/Value items to it's original data
Defaults to False. Note that the default is different from
`resolve`.
"""
normalized = normalize_key(key)
try:
node = super().select(normalized)
except ValueError as exc:
raise KeyNotInContext(key) from exc
assert isinstance(node, Node)
self._track_data(node)
return node.value if unwrap else node
@classmethod
def load_from(
cls, fs, path: str, select_keys: Optional[list[str]] = None
) -> "Context":
from dvc.utils.serialize import load_path
if not fs.exists(path):
raise ParamsLoadError(f"'{path}' does not exist")
if fs.isdir(path):
raise ParamsLoadError(f"'{path}' is a directory")
data = load_path(path, fs)
if not isinstance(data, Mapping):
typ = type(data).__name__
raise ParamsLoadError(
f"expected a dictionary, got '{typ}' in file '{path}'"
)
if select_keys:
try:
data = {key: data[key] for key in select_keys}
except KeyError as exc:
key, *_ = exc.args
raise ParamsLoadError(f"could not find '{key}' in '{path}'") from exc
meta = Meta(source=path, local=False)
ctx = cls(data, meta=meta)
ctx.imports[path] = select_keys
return ctx
def merge_update(self, other: "Context", overwrite=False):
matches = select(lambda key: key in other, self._reserved_keys.keys())
if matches:
raise ReservedKeyError(matches)
return super().merge_update(other, overwrite=overwrite)
def merge_from(self, fs, item: str, wdir: str, overwrite=False):
path, _, keys_str = item.partition(":")
path = fs.normpath(fs.join(wdir, path))
select_keys = lfilter(bool, keys_str.split(",")) if keys_str else None
if path in self.imports:
if not select_keys and self.imports[path] is None:
return # allow specifying complete filepath multiple times
self.check_loaded(path, item, select_keys)
ctx = Context.load_from(fs, path, select_keys)
try:
self.merge_update(ctx, overwrite=overwrite)
except ReservedKeyError as exc:
raise ReservedKeyError(exc.keys, item) from exc
cp = ctx.imports[path]
if path not in self.imports:
self.imports[path] = cp
elif cp:
self.imports[path].extend(cp)
def check_loaded(self, path, item, keys):
imported = self.imports[path]
if not keys and isinstance(imported, list):
raise VarsAlreadyLoaded(
f"cannot load '{item}' as it's partially loaded already"
)
if keys and imported is None:
raise VarsAlreadyLoaded(
f"cannot partially load '{item}' as it's already loaded."
)
if isinstance(imported, list) and set(keys) & set(imported):
raise VarsAlreadyLoaded(
f"cannot load '{item}' as it's partially loaded already"
)
def load_from_vars(
self,
fs,
vars_: list,
wdir: str,
stage_name: Optional[str] = None,
default: Optional[str] = None,
):
if default:
to_import = fs.join(wdir, default)
if fs.exists(to_import):
self.merge_from(fs, default, wdir)
else:
msg = "%s does not exist, it won't be used in parametrization"
logger.trace(msg, to_import)
stage_name = stage_name or ""
for index, item in enumerate(vars_):
assert isinstance(item, (str, dict))
if isinstance(item, str):
self.merge_from(fs, item, wdir)
else:
joiner = "." if stage_name else ""
meta = Meta(source=f"{stage_name}{joiner}vars[{index}]")
self.merge_update(Context(item, meta=meta))
def __deepcopy__(self, _):
new = Context(super().__deepcopy__(_))
new.meta = deepcopy(self.meta)
new.imports = deepcopy(self.imports)
new._reserved_keys = deepcopy(self._reserved_keys)
return new
@classmethod
def clone(cls, ctx: "Context") -> "Context":
"""Clones given context."""
return deepcopy(ctx)
@contextmanager
def reserved(self, *keys: str):
"""Allow reserving some keys so that they cannot be overwritten.
Ideally, we should delegate this to a separate container
and support proper namespacing so that we could support `env` features.
But for now, just `item` and `key`, this should do.
"""
# using dict to make the error messages ordered
new = dict.fromkeys([key for key in keys if key not in self._reserved_keys])
self._reserved_keys.update(new)
try:
yield
finally:
for key in new:
self._reserved_keys.pop(key)
@contextmanager
def set_temporarily(self, to_set: DictStr, reserve: bool = False):
cm = self.reserved(*to_set) if reserve else nullcontext()
non_existing = frozenset(to_set.keys() - self.keys())
prev = {key: self[key] for key in to_set if key not in non_existing}
temp = CtxDict(to_set)
self.update(temp)
try:
with cm:
yield
finally:
self.update(prev)
for key in non_existing:
self.data.pop(key, None)
def resolve(
self,
src,
unwrap=True,
skip_interpolation_checks=False,
key=None,
config=None,
) -> Any:
"""Recursively resolves interpolation and returns resolved data.
Args:
src: Data (str/list/dict etc.) to resolve
unwrap: Unwrap CtxDict/CtxList/Value to it's original data if
inside `src`. Defaults to True.
skip_interpolation_checks: Skip interpolation checks for error
The callee is responsible to check for errors in advance.
>>> c = Context({"three": 3})
>>> c.resolve({"lst": [1, 2, "${three}"]})
{'lst': [1, 2, 3]}
"""
func = recurse(self.resolve_str)
return func(src, unwrap, skip_interpolation_checks, key, config)
def resolve_str(
self,
src: str,
unwrap=True,
skip_interpolation_checks=False,
key=None,
config=None,
) -> str:
"""Resolves interpolated string to it's original value,
or in case of multiple interpolations, a combined string.
>>> c = Context({"enabled": True})
>>> c.resolve_str("${enabled}")
True
>>> c.resolve_str("enabled? ${enabled}")
'enabled? true'
"""
matches = get_matches(src)
if is_exact_string(src, matches):
# replace "${enabled}", if `enabled` is a boolean, with it's actual
# value rather than it's string counterparts.
expr = get_expression(matches[0], skip_checks=skip_interpolation_checks)
value = self.select(expr, unwrap=unwrap)
validate_value(value, key)
return value
# but not "${num} days"
return str_interpolate(
src,
matches,
self,
skip_checks=skip_interpolation_checks,
key=key,
config=config,
)
if __name__ == "__main__":
import doctest
doctest.testmod()