from typing import Callable, Any, Tuple, List, Dict, Type, NamedTuple
from torch.utils._pytree import PyTree, TreeSpec, LeafSpec
from collections import namedtuple
FlattenFuncSpec = Callable[[PyTree, TreeSpec], List]
SUPPORTED_NODES: Dict[Type[Any], Any] = {}
def register_pytree_flatten_spec(typ: Any, flatten_fn_spec: FlattenFuncSpec) -> None:
SUPPORTED_NODES[typ] = flatten_fn_spec
def tree_flatten_spec(pytree: PyTree, spec: TreeSpec) -> List[Any]:
if isinstance(spec, LeafSpec):
return [pytree]
if spec.type not in SUPPORTED_NODES:
raise RuntimeError(
f"{type(pytree)} does not have a flatten_fn_spec associated with it. Please register one with"
"torch.fx._pytree.register_pytree_flatten_spec. If you have serialized your model, make"
"sure that any custom pytrees have been registered before loading it.")
flatten_fn_spec = SUPPORTED_NODES[spec.type]
child_pytrees = flatten_fn_spec(pytree, spec)
result = []
for child, child_spec in zip(child_pytrees, spec.children_specs):
flat = tree_flatten_spec(child, child_spec)
result += flat
return result
def _dict_flatten_spec(d: Dict[Any, Any], spec: TreeSpec) -> List[Any]:
return [d[k] for k in spec.context]
def _list_flatten_spec(d: List[Any], spec: TreeSpec) -> List[Any]:
return [d[i] for i in range(len(spec.children_specs))]
def _tuple_flatten_spec(d: Tuple[Any], spec: TreeSpec) -> List[Any]:
return [d[i] for i in range(len(spec.children_specs))]
def _namedtuple_flatten_spec(d: NamedTuple, spec: TreeSpec) -> List[Any]:
return [d[i] for i in range(len(spec.children_specs))]
register_pytree_flatten_spec(dict, _dict_flatten_spec)
register_pytree_flatten_spec(list, _list_flatten_spec)
register_pytree_flatten_spec(tuple, _tuple_flatten_spec)
register_pytree_flatten_spec(namedtuple, _tuple_flatten_spec)