# --------------------------------------------------------------------------------------
# Copyright (c) 2013-2021, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
# --------------------------------------------------------------------------------------
from .catom import DefaultValue, DelAttr, Member, SetAttr, Validate
from .typing_utils import extract_types
class Value(Member):
"""A member class which supports value initialization.
A plain `Value` provides support for default values and factories,
but does not perform any type checking or validation. It serves as
a useful base class for scalar members and can be used for cases
where type checking is not needed (like private attributes).
"""
__slots__ = ()
def __init__(self, default=None, *, factory=None):
"""Initialize a Value.
Parameters
----------
default : object, optional
The default value for the member. If this is provided, it
should be an immutable value. The value will will not be
copied between owner instances.
factory : callable, optional
A callable object which is called with zero arguments and
returns a default value for the member. This will override
any value given by `default`.
"""
if factory is not None:
self.set_default_value_mode(DefaultValue.CallObject, factory)
else:
self.set_default_value_mode(DefaultValue.Static, default)
class ReadOnly(Value):
"""A value which can be assigned once and is then read-only."""
__slots__ = ()
def __init__(self, kind=None, *, default=None, factory=None):
super(ReadOnly, self).__init__(default, factory=factory)
self.set_setattr_mode(SetAttr.ReadOnly, None)
self.set_delattr_mode(DelAttr.ReadOnly, None)
if kind:
self.set_validate_mode(Validate.Instance, extract_types(kind))
class Constant(Value):
"""A value which cannot be changed from its default."""
__slots__ = ()
def __init__(self, default=None, *, factory=None, kind=None):
super(Constant, self).__init__(default, factory=factory)
self.set_setattr_mode(SetAttr.Constant, None)
self.set_delattr_mode(DelAttr.Constant, None)
if kind:
self.set_validate_mode(Validate.Instance, extract_types(kind))
class Callable(Value):
"""A value which is callable."""
__slots__ = ()
def __init__(self, default=None, *, factory=None):
super(Callable, self).__init__(default, factory=factory)
self.set_validate_mode(Validate.Callable, None)
class Bool(Value):
"""A value of type `bool`."""
__slots__ = ()
def __init__(self, default=False, *, factory=None):
super(Bool, self).__init__(default, factory=factory)
self.set_validate_mode(Validate.Bool, None)
class Int(Value):
"""A value of type `int`.
By default, ints are strictly typed. Pass strict=False to the
constructor to enable int casting for longs and floats.
"""
__slots__ = ()
def __init__(self, default=0, *, factory=None, strict=True):
super(Int, self).__init__(default, factory=factory)
if strict:
self.set_validate_mode(Validate.Int, None)
else:
self.set_validate_mode(Validate.IntPromote, None)
class FloatRange(Value):
"""A float value clipped to a range.
By default, ints and longs will be promoted to floats. Pass
strict=True to the constructor to enable strict float checking.
"""
__slots__ = ()
def __init__(self, low=None, high=None, value=None, *, strict=False):
if low is not None and high is not None and low > high:
low, high = high, low
default = 0.0
if value is not None:
default = value
elif low is not None:
default = low
elif high is not None:
default = high
super(FloatRange, self).__init__(default)
if strict:
self.set_validate_mode(Validate.FloatRange, (low, high))
else:
self.set_validate_mode(Validate.FloatRangePromote, (low, high))
class Range(Value):
"""An integer value clipped to a range."""
__slots__ = ()
def __init__(self, low=None, high=None, value=None):
if low is not None and high is not None and low > high:
low, high = high, low
default = 0
if value is not None:
default = value
elif low is not None:
default = low
elif high is not None:
default = high
super(Range, self).__init__(default)
self.set_validate_mode(Validate.Range, (low, high))
class Float(Value):
"""A value of type `float`.
By default, ints and longs will be promoted to floats. Pass
strict=True to the constructor to enable strict float checking.
"""
__slots__ = ()
def __init__(self, default=0.0, *, factory=None, strict=False):
super(Float, self).__init__(default, factory=factory)
if strict:
self.set_validate_mode(Validate.Float, None)
else:
self.set_validate_mode(Validate.FloatPromote, None)
class Bytes(Value):
"""A value of type `bytes`.
By default, strings will NOT be promoted to bytes. Pass strict=False to the
constructor to enable loose byte checking.
"""
__slots__ = ()
def __init__(self, default=b"", *, factory=None, strict=True):
super(Bytes, self).__init__(default, factory=factory)
if strict:
self.set_validate_mode(Validate.Bytes, None)
else:
self.set_validate_mode(Validate.BytesPromote, None)
class Str(Value):
"""A value of type `str`.
By default, bytes will NOT be promoted to strings. Pass strict=False to the
constructor to enable loose string checking.
"""
def __init__(self, default="", *, factory=None, strict=True):
super(Str, self).__init__(default, factory=factory)
if strict:
self.set_validate_mode(Validate.Str, None)
else:
self.set_validate_mode(Validate.StrPromote, None)
