def _unfold(self, op: Operator, n: int) -> Optional[Operator]:
"""Unroll all possible operators from the grammar `g` starting from non-terminal `op` after `n` derivations.
Parameters
----------
op : Operator
starting rule (e.g., `g.start`)
n : int
number of derivations
Returns
-------
Optional[Operator]
"""
if isinstance(op, BasePipeline):
steps = op.steps_list()
new_maybe_steps: List[Optional[Operator]] = [
self._unfold(sop, n) for sop in op.steps_list()
]
if None not in new_maybe_steps:
new_steps: List[Operator] = cast(List[Operator],
new_maybe_steps)
step_map = {steps[i]: new_steps[i] for i in range(len(steps))}
new_edges = [(step_map[s], step_map[d]) for s, d in op.edges()]
return make_pipeline_graph(new_steps, new_edges, True)
else:
return None
if isinstance(op, OperatorChoice):
steps = [
s for s in (self._unfold(sop, n) for sop in op.steps_list())
if s
]
return make_choice(*steps) if steps else None
if isinstance(op, NonTerminal):
return self._unfold(self._variables[op.name()], n -
1) if n > 0 else None
if isinstance(op, IndividualOp):
return op
assert False, f"Unknown operator {op}"
def _sample(self, op: Operator, n: int) -> Optional[Operator]:
"""
Sample the grammar `g` starting from `g.start`, that is, choose one element at random for each possible choices.
Parameters
----------
op : Operator
starting rule (e.g., `g.start`)
n : int
number of derivations
Returns
-------
Optional[Operator]
"""
if isinstance(op, BasePipeline):
steps = op.steps_list()
new_maybe_steps: List[Optional[Operator]] = [
self._sample(sop, n) for sop in op.steps_list()
]
if None not in new_maybe_steps:
new_steps: List[Operator] = cast(List[Operator],
new_maybe_steps)
step_map = {steps[i]: new_steps[i] for i in range(len(steps))}
new_edges = [(step_map[s], step_map[d]) for s, d in op.edges()]
return make_pipeline_graph(new_steps, new_edges, True)
else:
return None
if isinstance(op, OperatorChoice):
return self._sample(random.choice(op.steps_list()), n)
if isinstance(op, NonTerminal):
return self._sample(getattr(self, op.name()), n -
1) if n > 0 else None
if isinstance(op, IndividualOp):
return op
assert False, f"Unknown operator {op}"