# Copyright 2022 The GPflow Contributors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
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# http://www.apache.org/licenses/LICENSE-2.0
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"""
Code for specifying and evaluating boolean expressions.
"""
from abc import ABC, abstractmethod
from dataclasses import dataclass
from enum import Enum
from typing import Any, Callable, Mapping, Tuple, cast
from .argument_ref import ArgumentRef
from .error_contexts import ErrorContext, ObjectValueContext, ParallelContext, StackContext
[docs]class ParsedBoolSpec(ABC):
""" A boolean expression. """
[docs] @abstractmethod
def get(self, arg_map: Mapping[str, Any], context: ErrorContext) -> Tuple[bool, ErrorContext]:
""" Evaluate this boolean value. """
def _paren_repr(spec: ParsedBoolSpec) -> str:
"""
Return the `repr` of `spec`, wrapping it in parenthesis if it is a non-trivial expression.
"""
result = repr(spec)
if isinstance(spec, ParsedArgumentRefBoolSpec) and spec.bool_test == BoolTest.BOOL:
return result
return f"({result})"
[docs]@dataclass(frozen=True)
class ParsedOrBoolSpec(ParsedBoolSpec):
""" An "or" expression. """
left: ParsedBoolSpec
right: ParsedBoolSpec
[docs] def get(self, arg_map: Mapping[str, Any], context: ErrorContext) -> Tuple[bool, ErrorContext]:
left_value, left_context = self.left.get(arg_map, context)
right_value, right_context = self.right.get(arg_map, context)
return (left_value or right_value), ParallelContext((left_context, right_context))
def __repr__(self) -> str:
return f"{_paren_repr(self.left)} or {_paren_repr(self.right)}"
[docs]@dataclass(frozen=True)
class ParsedAndBoolSpec(ParsedBoolSpec):
""" An "and" expression. """
left: ParsedBoolSpec
right: ParsedBoolSpec
[docs] def get(self, arg_map: Mapping[str, Any], context: ErrorContext) -> Tuple[bool, ErrorContext]:
left_value, left_context = self.left.get(arg_map, context)
right_value, right_context = self.right.get(arg_map, context)
return (left_value and right_value), ParallelContext((left_context, right_context))
def __repr__(self) -> str:
return f"{_paren_repr(self.left)} and {_paren_repr(self.right)}"
[docs]@dataclass(frozen=True)
class ParsedNotBoolSpec(ParsedBoolSpec):
""" A "not" expression. """
right: ParsedBoolSpec
[docs] def get(self, arg_map: Mapping[str, Any], context: ErrorContext) -> Tuple[bool, ErrorContext]:
right_value, right_context = self.right.get(arg_map, context)
return (not right_value), right_context
def __repr__(self) -> str:
return f"not {_paren_repr(self.right)}"
[docs]class BoolTest(Enum):
"""
Strategies for converting a value to ``bool``.
"""
BOOL = (bool, lambda arg: arg)
IS_NONE = ((lambda x: x is None), lambda arg: f"{arg} is None")
IS_NOT_NONE = ((lambda x: x is not None), lambda arg: f"{arg} is not None")
@property
def to_bool(self) -> Callable[[Any], bool]:
return cast(Callable[[Any], bool], self.value[0])
@property
def repr(self) -> Callable[[str], str]:
return cast(Callable[[str], str], self.value[1])
[docs]@dataclass(frozen=True)
class ParsedArgumentRefBoolSpec(ParsedBoolSpec):
""" A reference to an input argument. """
argument_ref: ArgumentRef
bool_test: BoolTest
[docs] def get(self, arg_map: Mapping[str, Any], context: ErrorContext) -> Tuple[bool, ErrorContext]:
((arg_value, relative_context),) = self.argument_ref.get(arg_map, context)
bool_value = self.bool_test.to_bool(arg_value)
return bool_value, StackContext(relative_context, ObjectValueContext(arg_value))
def __repr__(self) -> str:
return self.bool_test.repr(repr(self.argument_ref))