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"""Define type and structure for query language.""" |
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from enum import Enum, unique |
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from typing import Any, Callable, List, NamedTuple, Optional, Tuple, Type, Union |
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__all__ = [ |
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'Path', |
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"Evaluator", |
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"operator_factory", |
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"OperatoryArity", |
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"OperatorDefinition", |
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"ItemAST", |
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"NETWORKX_OPERATORS_REGISTERY", |
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"register_operator", |
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] |
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NETWORKX_OPERATORS_REGISTERY = {} |
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"""Internal registry of operators.""" |
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Path = Union[Tuple, str] |
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"""Node attribut path definition.""" |
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Evaluator = Callable[[Any], bool] |
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"""Predicate function.""" |
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def operator_factory(op_function: Callable, *args: Any) -> Evaluator: |
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"""Add context parameter to operator function. |
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Arguments: |
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op_function (Callable): any function with context evaluation has first parameter |
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*args (Any): a list of parameter to enclose |
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Returns: |
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(Evaluator): evaluator function with single argument |
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""" |
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return lambda context: op_function(context, *args) |
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@unique |
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class OperatoryArity(Enum): |
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"""Define operator arity constant.""" |
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UNARY = 1 |
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BINARY = 2 |
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TERNARY = 3 |
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NARY = 42 |
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@property |
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def arity(self) -> int: |
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"""Returns awaiting arity of associated function.""" |
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return self.value if self != OperatoryArity.NARY else 1 |
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def is_compliant(self, parameters) -> Tuple[bool, int]: |
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"""Check if parameters cardinality is compliant with operator arity. |
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Returns: |
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(Tuple[bool, int]): (compliant, delta_paramaters) |
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compliant is true if this is compliante |
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delta_paramaters: |
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- 0 if compliante, |
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- < 0 if some parameters is missing, |
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- > 0 if too much parameters is given |
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""" |
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# context parameter is ommited here |
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count = len(parameters) |
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if self.value == OperatoryArity.NARY.value: |
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match = count > 0 |
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return (match, 0 if match else -1) |
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match = (count + 1) == self.arity |
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delta = (count + 1) - self.arity |
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return (match, 0 if match else delta) |
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class OperatorDefinition(NamedTuple): |
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"""Operator definition. |
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Attributes: |
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name (str): operator shortname |
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function (Callable): first argument must be a context to evaluate |
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arity (OperatoryArity): arity of operator function |
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combinator (Optional[bool]): Flag which indicate if this operator is a combination of other operator |
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profile (Optional[List[Type]]): optional function profile |
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alias (Optional[str]): optional alias name for this operator |
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""" |
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name: str |
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function: Callable |
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arity: OperatoryArity |
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combinator: Optional[bool] = False |
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profile: Optional[List[Type]] = None |
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alias: Optional[str] = None |
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def __str__(self): |
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return self.name |
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class ItemAST(NamedTuple): |
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"""Define our AST.""" |
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op: OperatorDefinition |
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args: List[Any] |
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def check_arity(self) -> Tuple[bool, int]: |
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"""Check arity of this item against operator definition. |
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Utilities short cut to OperatorDefinition#OperatoryArity#is_compliant. |
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Returns: |
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(Tuple[bool, int]): (match, delta_parameters_count) |
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""" |
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return self.op.arity.is_compliant(self.args) |
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def check_profile(self) -> bool: # pragma: no cover |
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# TODO Fix: did not work with generic... |
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if self.op.profile: |
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if not self.op.combinator: |
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# terminal operator |
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for i in range(1, self.op.arity.value): # we omit first parameters (not in args) |
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if not isinstance(self.args[i - 1], self.op.profile[i]): |
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return False |
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else: |
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for arg in self.args: |
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if not isinstance(arg, self.op.profile[1]): |
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return False |
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return True |
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class ParserException(RuntimeError): |
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"""Define a parser exception with stack of expression.""" |
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def __init__(self, message, stack): |
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super(RuntimeError, self).__init__(message) |
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self.stack = stack |
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def register_operator( |
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name: str, |
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arity: OperatoryArity, |
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combinator: Optional[bool] = False, |
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profile: Optional[List[Any]] = None, |
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alias: Optional[str] = None, |
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): |
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"""Register an operator.""" |
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global NETWORKX_OPERATORS_REGISTERY |
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def decorate_function(f): |
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_definition = OperatorDefinition( |
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name=name, function=f, arity=arity, combinator=combinator, profile=profile, alias=alias |
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) |
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NETWORKX_OPERATORS_REGISTERY[_definition.name] = _definition |
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if alias: |
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NETWORKX_OPERATORS_REGISTERY[alias] = _definition |
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return f |
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return decorate_function |
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