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90 lines
3.3 KiB
Python
90 lines
3.3 KiB
Python
# ast_utils.py
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#
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# Copyright 2021 James Westman <james@jwestman.net>
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#
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# This file is free software; you can redistribute it and/or modify it
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# under the terms of the GNU Lesser General Public License as
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# published by the Free Software Foundation; either version 3 of the
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# License, or (at your option) any later version.
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#
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# This file is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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# SPDX-License-Identifier: LGPL-3.0-or-later
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from .errors import *
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class Validator:
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def __init__(self, func, token_name=None, end_token_name=None):
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self.func = func
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self.token_name = token_name
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self.end_token_name = end_token_name
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def __get__(self, instance, owner):
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if instance is None:
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return self
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key = "_validation_result_" + self.func.__name__
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if key + "_err" in instance.__dict__:
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# If the validator has failed before, raise a generic Exception.
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# We want anything that depends on this validation result to
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# fail, but not report the exception twice.
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raise AlreadyCaughtError()
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if key not in instance.__dict__:
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try:
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instance.__dict__[key] = self.func(instance)
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except CompileError as e:
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# Mark the validator as already failed so we don't print the
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# same message again
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instance.__dict__[key + "_err"] = True
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# This mess of code sets the error's start and end positions
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# from the tokens passed to the decorator, if they have not
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# already been set
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if self.token_name is not None and e.start is None:
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group = instance.group.tokens.get(self.token_name)
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if self.end_token_name is not None and group is None:
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group = instance.group.tokens[self.end_token_name]
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e.start = group.start
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if (self.token_name is not None or self.end_token_name is not None) and e.end is None:
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e.end = instance.group.tokens[self.end_token_name or self.token_name].end
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# Re-raise the exception
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raise e
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# Return the validation result (which other validators, or the code
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# generation phase, might depend on)
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return instance.__dict__[key]
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def validate(*args, **kwargs):
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""" Decorator for functions that validate an AST node. Exceptions raised
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during validation are marked with range information from the tokens. Also
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creates a cached property out of the function. """
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def decorator(func):
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return Validator(func, *args, **kwargs)
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return decorator
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class Docs:
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def __init__(self, func, token_name=None):
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self.func = func
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self.token_name = token_name
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def docs(*args, **kwargs):
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""" Decorator for functions that return documentation for tokens. """
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def decorator(func):
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return Docs(func, *args, **kwargs)
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return decorator
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