#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2024, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
#
# The full license is in the file LICENSE.txt, distributed with this software.
#-----------------------------------------------------------------------------
""" Provide base classes for the Bokeh property system.
.. note::
These classes form part of the very low-level machinery that implements
the Bokeh model and property system. It is unlikely that any of these
classes or their methods will be applicable to any standard usage or to
anyone who is not directly developing on Bokeh's own infrastructure.
"""
#-----------------------------------------------------------------------------
# Boilerplate
#-----------------------------------------------------------------------------
from __future__ import annotations
import logging # isort:skip
log = logging.getLogger(__name__)
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
# Standard library imports
from copy import copy
from typing import (
TYPE_CHECKING,
Any,
Callable,
ClassVar,
TypeVar,
Union,
)
# Bokeh imports
from ...util.dependencies import uses_pandas
from ...util.strings import nice_join
from ..has_props import HasProps
from ._sphinx import property_link, register_type_link, type_link
from .descriptor_factory import PropertyDescriptorFactory
from .descriptors import PropertyDescriptor
from .singletons import (
Intrinsic,
IntrinsicType,
Undefined,
UndefinedType,
)
if TYPE_CHECKING:
from typing_extensions import TypeAlias
from ...document.events import DocumentPatchedEvent
#-----------------------------------------------------------------------------
# Globals and constants
#-----------------------------------------------------------------------------
__all__ = (
'ContainerProperty',
'PrimitiveProperty',
'Property',
'validation_on',
)
#-----------------------------------------------------------------------------
# General API
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Dev API
#-----------------------------------------------------------------------------
T = TypeVar("T")
TypeOrInst: TypeAlias = Union[type[T], T]
Init: TypeAlias = Union[T, UndefinedType, IntrinsicType]
[docs]
class Property(PropertyDescriptorFactory[T]):
""" Base class for Bokeh property instances, which can be added to Bokeh
Models.
Args:
default (obj, optional) :
A default value for attributes created from this property to have.
help (str or None, optional) :
A documentation string for this property. It will be automatically
used by the :ref:`bokeh.sphinxext.bokeh_prop` extension when
generating Spinx documentation. (default: None)
"""
# This class attribute is controlled by external helper API for validation
_should_validate: ClassVar[bool] = True
_readonly: ClassVar[bool] = False
_serialized: ClassVar[bool] = True
_self_serialized: bool
alternatives: list[tuple[Property[Any], Callable[[Any], T]]]
assertions: list[tuple[Callable[[HasProps, T], bool], str | Callable[[HasProps, str, T], None]]]
[docs]
def __init__(self, *, default: Init[T] = Intrinsic, help: str | None = None) -> None:
default = default if default is not Intrinsic else Undefined
if self._serialized:
self._self_serialized = not (self.readonly and default is Undefined)
else:
self._self_serialized = False
self._default = default
self._help = help
self.__doc__ = help
self.alternatives = []
self.assertions = []
@property
def default(self) -> Init[T]:
return self._default
@property
def help(self) -> str | None:
return self._help
[docs]
def __str__(self) -> str:
return self.__class__.__name__
[docs]
def __repr__(self) -> str:
return str(self)
[docs]
def __call__(self, *, default: Init[T] = Intrinsic, help: str | None = None) -> Property[T]:
""" Clone this property and allow to override ``default`` and ``help``. """
default = self._default if default is Intrinsic else default
help = self._help if help is None else help
prop = self.__class__(default=default, help=help)
prop.alternatives = list(self.alternatives)
prop.assertions = list(self.assertions)
return prop
[docs]
def __eq__(self, other: object) -> bool:
if isinstance(other, self.__class__):
return (
self._default == other._default and
self._help == other._help and
self.alternatives == other.alternatives and
self.assertions == other.assertions
)
else:
return False
[docs]
def make_descriptors(self, name: str) -> list[PropertyDescriptor[T]]:
""" Return a list of ``PropertyDescriptor`` instances to install
on a class, in order to delegate attribute access to this property.
Args:
name (str) : the name of the property these descriptors are for
Returns:
list[PropertyDescriptor]
The descriptors returned are collected by the ``MetaHasProps``
metaclass and added to ``HasProps`` subclasses during class creation.
"""
return [ PropertyDescriptor(name, self) ]
def _may_have_unstable_default(self) -> bool:
""" False if we have a default that is immutable, and will be the
same every time (some defaults are generated on demand by a function
to be called).
"""
return callable(self._default)
@classmethod
def _copy_default(cls, default: Callable[[], T] | T, *, no_eval: bool = False) -> T:
""" Return a copy of the default, or a new value if the default
is specified by a function.
"""
if not callable(default):
return copy(default)
else:
if no_eval:
return default
return default()
def _raw_default(self, *, no_eval: bool = False) -> T:
""" Return the untransformed default value.
The raw_default() needs to be validated and transformed by
prepare_value() before use, and may also be replaced later by
subclass overrides or by themes.
"""
return self._copy_default(self._default, no_eval=no_eval)
[docs]
def themed_default(self, cls: type[HasProps], name: str, theme_overrides: dict[str, Any] | None, *, no_eval: bool = False) -> T:
""" The default, transformed by prepare_value() and the theme overrides.
"""
overrides = theme_overrides
if overrides is None or name not in overrides:
overrides = cls._overridden_defaults()
if name in overrides:
default = self._copy_default(overrides[name], no_eval=no_eval)
else:
default = self._raw_default(no_eval=no_eval)
return self.prepare_value(cls, name, default)
@property
def serialized(self) -> bool:
""" Whether the property should be serialized when serializing an object.
This would be False for a "virtual" or "convenience" property that duplicates
information already available in other properties, for example.
"""
return self._self_serialized
@property
def readonly(self) -> bool:
""" Whether this property is read-only.
Read-only properties may only be modified by the client (i.e., by BokehJS
in the browser).
"""
return self._readonly
[docs]
def matches(self, new: T, old: T) -> bool:
""" Whether two parameters match values.
If either ``new`` or ``old`` is a NumPy array or Pandas Series or Index,
then the result of ``np.array_equal`` will determine if the values match.
Otherwise, the result of standard Python equality will be returned.
Returns:
True, if new and old match, False otherwise
"""
import numpy as np
if isinstance(new, np.ndarray) or isinstance(old, np.ndarray):
return np.array_equal(new, old)
if uses_pandas(new) or uses_pandas(old):
import pandas as pd
if isinstance(new, pd.Series) or isinstance(old, pd.Series):
return np.array_equal(new, old)
if isinstance(new, pd.Index) or isinstance(old, pd.Index):
return np.array_equal(new, old)
try:
# this handles the special but common case where there is a dict with array
# or series as values (e.g. the .data property of a ColumnDataSource)
if isinstance(new, dict) and isinstance(old, dict):
if set(new.keys()) != set(old.keys()):
return False
return all(self.matches(new[k], old[k]) for k in new)
# FYI Numpy can erroneously raise a warning about elementwise
# comparison here when a timedelta is compared to another scalar.
# https://github.com/numpy/numpy/issues/10095
return new == old
# if the comparison fails for some reason, just punt and return no-match
except ValueError:
return False
[docs]
def validate(self, value: Any, detail: bool = True) -> None:
""" Determine whether we can set this property from this value.
Validation happens before transform()
Args:
value (obj) : the value to validate against this property type
detail (bool, options) : whether to construct detailed exceptions
Generating detailed type validation error messages can be
expensive. When doing type checks internally that will not
escape exceptions to users, these messages can be skipped
by setting this value to False (default: True)
Returns:
None
Raises:
ValueError if the value is not valid for this property type
"""
pass
[docs]
def is_valid(self, value: Any) -> bool:
""" Whether the value passes validation
Args:
value (obj) : the value to validate against this property type
Returns:
True if valid, False otherwise
"""
try:
if validation_on():
self.validate(value, False)
except ValueError:
return False
else:
return True
[docs]
def wrap(self, value: T) -> T:
""" Some property types need to wrap their values in special containers, etc.
"""
return value
def _hinted_value(self, value: Any, hint: DocumentPatchedEvent | None) -> Any:
return value
def prepare_value(self, owner: HasProps | type[HasProps], name: str, value: Any, *, hint: DocumentPatchedEvent | None = None) -> T:
if value is Intrinsic:
value = self._raw_default()
if value is Undefined:
return value
error = None
try:
if validation_on():
hinted_value = self._hinted_value(value, hint)
self.validate(hinted_value)
except ValueError as e:
for tp, converter in self.alternatives:
if tp.is_valid(value):
value = converter(value)
break
else:
error = e
if error is None:
value = self.transform(value)
else:
obj_repr = owner if isinstance(owner, HasProps) else owner.__name__
raise ValueError(f"failed to validate {obj_repr}.{name}: {error}")
if isinstance(owner, HasProps):
obj = owner
for fn, msg_or_fn in self.assertions:
if isinstance(fn, bool):
result = fn
else:
result = fn(obj, value)
assert isinstance(result, bool)
if not result:
if isinstance(msg_or_fn, str):
raise ValueError(msg_or_fn)
else:
msg_or_fn(obj, name, value)
return self.wrap(value)
@property
def has_ref(self) -> bool:
return False
[docs]
def accepts(self, tp: TypeOrInst[Property[Any]], converter: Callable[[Any], T]) -> Property[T]:
""" Declare that other types may be converted to this property type.
Args:
tp (Property) :
A type that may be converted automatically to this property
type.
converter (callable) :
A function accepting ``value`` to perform conversion of the
value to this property type.
Returns:
self
"""
tp = ParameterizedProperty._validate_type_param(tp)
self.alternatives.append((tp, converter))
return self
[docs]
def asserts(self, fn: Callable[[HasProps, T], bool], msg_or_fn: str | Callable[[HasProps, str, T], None]) -> Property[T]:
""" Assert that prepared values satisfy given conditions.
Assertions are intended in enforce conditions beyond simple value
type validation. For instance, this method can be use to assert that
the columns of a ``ColumnDataSource`` all collectively have the same
length at all times.
Args:
fn (callable) :
A function accepting ``(obj, value)`` that returns True if the value
passes the assertion, or False otherwise.
msg_or_fn (str or callable) :
A message to print in case the assertion fails, or a function
accepting ``(obj, name, value)`` to call in in case the assertion
fails.
Returns:
self
"""
self.assertions.append((fn, msg_or_fn))
return self
def replace(self, old: type[Property[Any]], new: Property[Any]) -> Property[Any]:
if self.__class__ == old:
return new
else:
return self
class ParameterizedProperty(Property[T]):
""" A base class for Properties that have type parameters, e.g. ``List(String)``.
"""
_type_params: list[Property[Any]]
def __init__(self, *type_params: TypeOrInst[Property[T]], default: Init[T] = Intrinsic, help: str | None = None) -> None:
_type_params = [ self._validate_type_param(param) for param in type_params ]
default = default if default is not Intrinsic else _type_params[0]._raw_default()
self._type_params = _type_params
super().__init__(default=default, help=help)
def __str__(self) -> str:
class_name = self.__class__.__name__
item_types = ", ".join(str(x) for x in self.type_params)
return f"{class_name}({item_types})"
def __call__(self, *, default: Init[T] = Intrinsic, help: str | None = None) -> ParameterizedProperty[T]:
""" Clone this property and allow to override ``default`` and ``help``. """
default = self._default if default is Intrinsic else default
help = self._help if help is None else help
prop = self.__class__(*self.type_params, default=default, help=help)
prop.alternatives = list(self.alternatives)
prop.assertions = list(self.assertions)
return prop
def __eq__(self, other: object) -> bool:
if isinstance(other, self.__class__):
return super().__eq__(other) and self.type_params == other.type_params
else:
return False
@staticmethod
def _validate_type_param(type_param: TypeOrInst[Property[Any]], *, help_allowed: bool = False) -> Property[Any]:
if isinstance(type_param, type):
if issubclass(type_param, Property):
return type_param()
else:
type_param = type_param.__name__
elif isinstance(type_param, Property):
if type_param._help is not None and not help_allowed:
raise ValueError("setting 'help' on type parameters doesn't make sense")
return type_param
raise ValueError(f"expected a Property as type parameter, got {type_param}")
@property
def type_params(self) -> list[Property[Any]]:
return self._type_params
@property
def has_ref(self) -> bool:
return any(type_param.has_ref for type_param in self.type_params)
def _may_have_unstable_default(self) -> bool:
return super()._may_have_unstable_default() or \
any(type_param._may_have_unstable_default() for type_param in self.type_params)
def replace(self, old: type[Property[Any]], new: Property[Any]) -> Property[Any]:
if self.__class__ == old:
return new
else:
params = [ type_param.replace(old, new) for type_param in self.type_params ]
return self.__class__(*params)
class SingleParameterizedProperty(ParameterizedProperty[T]):
""" A parameterized property with a single type parameter. """
@property
def type_param(self) -> Property[T]:
return self._type_params[0]
def __init__(self, type_param: TypeOrInst[Property[Any]], *, default: Init[T] = Intrinsic, help: str | None = None):
super().__init__(type_param, default=default, help=help)
def validate(self, value: Any, detail: bool = True) -> None:
super().validate(value, detail=detail)
self.type_param.validate(value, detail=detail)
def transform(self, value: T) -> T:
return self.type_param.transform(value)
def wrap(self, value: T) -> T:
return self.type_param.wrap(value)
[docs]
class PrimitiveProperty(Property[T]):
""" A base class for simple property types.
Subclasses should define a class attribute ``_underlying_type`` that is
a tuple of acceptable type values for the property.
Example:
A trivial version of a ``Float`` property might look like:
.. code-block:: python
class Float(PrimitiveProperty):
_underlying_type = (numbers.Real,)
"""
_underlying_type: ClassVar[tuple[type[Any], ...]]
[docs]
def validate(self, value: Any, detail: bool = True) -> None:
super().validate(value, detail)
if isinstance(value, self._underlying_type):
return
if not detail:
raise ValueError("")
expected_type = nice_join([ cls.__name__ for cls in self._underlying_type ])
msg = f"expected a value of type {expected_type}, got {value} of type {type(value).__name__}"
raise ValueError(msg)
[docs]
class ContainerProperty(ParameterizedProperty[T]):
""" A base class for Container-like type properties.
"""
def _may_have_unstable_default(self) -> bool:
# all containers are mutable, so the default can be modified
return self._default is not Undefined
[docs]
def validation_on() -> bool:
""" Check if property validation is currently active
Returns:
bool
"""
return Property._should_validate
#-----------------------------------------------------------------------------
# Private API
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
@register_type_link(SingleParameterizedProperty)
def _sphinx_type(obj: SingleParameterizedProperty[Any]):
return f"{property_link(obj)}({type_link(obj.type_param)})"
