# MIT License
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# Copyright The SCons Foundation
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"""Variable type for true/false Variables.
Usage example::
opts = Variables()
opts.Add(BoolVariable('embedded', 'build for an embedded system', False))
...
if env['embedded']:
...
"""
from typing import Tuple, Callable
import SCons.Errors
__all__ = ['BoolVariable',]
TRUE_STRINGS = ('y', 'yes', 'true', 't', '1', 'on' , 'all')
FALSE_STRINGS = ('n', 'no', 'false', 'f', '0', 'off', 'none')
[docs]def _text2bool(val: str) -> bool:
"""Convert boolean-like string to boolean.
If *val* looks like it expresses a bool-like value, based on
the :const:`TRUE_STRINGS` and :const:`FALSE_STRINGS` tuples,
return the appropriate value.
This is usable as a converter function for SCons Variables.
Raises:
ValueError: if *val* cannot be converted to boolean.
"""
lval = val.lower()
if lval in TRUE_STRINGS:
return True
if lval in FALSE_STRINGS:
return False
raise ValueError("Invalid value for boolean option: %s" % val)
[docs]def _validator(key, val, env) -> None:
"""Validate that the value of *key* in *env* is a boolean.
Parmaeter *val* is not used in the check.
Usable as a validator function for SCons Variables.
Raises:
KeyError: if *key* is not set in *env*
UserError: if the value of *key* is not ``True`` or ``False``.
"""
if not env[key] in (True, False):
raise SCons.Errors.UserError(
'Invalid value for boolean option %s: %s' % (key, env[key])
)
[docs]def BoolVariable(key, help, default) -> Tuple[str, str, str, Callable, Callable]:
"""Return a tuple describing a boolean SCons Variable.
The input parameters describe a boolean option. Returns a tuple
including the correct converter and validator.
The *help* text will have ``(yes|no)`` automatically appended to show the
valid values. The result is usable as input to :meth:`Add`.
"""
help = '%s (yes|no)' % help
return (key, help, default, _validator, _text2bool)
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