eth2.0-specs/tests/core/pyspec/eth2spec/debug/decode.py

from typing import Any
from eth2spec.utils.ssz.ssz_impl import hash_tree_root
from eth2spec.utils.ssz.ssz_typing import (
    uint, Container, List, boolean,
    Vector, ByteVector, ByteList, Union, View
)


def decode(data: Any, typ):
    if issubclass(typ, (uint, boolean)):
        return typ(data)
    elif issubclass(typ, (List, Vector)):
        return typ(decode(element, typ.element_cls()) for element in data)
    elif issubclass(typ, ByteVector):
        return typ(bytes.fromhex(data[2:]))
    elif issubclass(typ, ByteList):
        return typ(bytes.fromhex(data[2:]))
    elif issubclass(typ, Container):
        temp = {}
        for field_name, field_type in typ.fields().items():
            temp[field_name] = decode(data[field_name], field_type)
            if field_name + "_hash_tree_root" in data:
                assert (data[field_name + "_hash_tree_root"][2:] ==
                        hash_tree_root(temp[field_name]).hex())
        ret = typ(**temp)
        if "hash_tree_root" in data:
            assert (data["hash_tree_root"][2:] ==
                    hash_tree_root(ret).hex())
        return ret
    elif issubclass(typ, Union):
        selector = int(data["selector"])
        options = typ.options()
        value_typ = options[selector]
        value: View
        if value_typ is None:  # handle the "nil" type case
            assert data["value"] is None
            value = None
        else:
            value = decode(data["value"], value_typ)
        return typ(selector=selector, value=value)
    else:
        raise Exception(f"Type not recognized: data={data}, typ={typ}")