state.py

from abc import abstractmethod
from typing import Optional


class State:

    @abstractmethod
    def set(self, key: bytes, value: bytes):
        raise NotImplementedError

    @abstractmethod
    def get(self, key: bytes, isCommitted: bool=True) -> Optional[bytes]:
        # If `isCommitted` is True then get value corresponding to the
        # committed state else get the latest value
        raise NotImplementedError

    @abstractmethod
    def get_for_root_hash(self, root_hash, key: bytes) -> Optional[bytes]:
        '''
        Gets a value corresponded to the key for a given root_hash
        :param root_hash: a hash of the root get the value for
        :param key: a key in the trie corresponded to the root
        :return: a value (in bytes) or None
        '''
        raise NotImplementedError

    @abstractmethod
    def remove(self, key: bytes):
        raise NotImplementedError

    @abstractmethod
    def commit(self, rootHash=None, rootNode=None):
        raise NotImplementedError

    @abstractmethod
    def revertToHead(self, headHash=None):
        # Revert to the given head
        raise NotImplementedError

    @abstractmethod
    def close(self):
        raise NotImplementedError

    @property
    @abstractmethod
    def head(self):
        # The current head of the state, if the state is a merkle tree then
        # head is the root
        raise NotImplementedError

    @property
    @abstractmethod
    def committedHead(self):
        # The committed head of the state, if the state is a merkle tree then
        # head is the root
        raise NotImplementedError

    @property
    @abstractmethod
    def headHash(self):
        """
        The hash of the current head of the state, if the state is a merkle
        tree then hash of the root
        :return:
        """
        raise NotImplementedError

    @property
    @abstractmethod
    def committedHeadHash(self):
        raise NotImplementedError

    @property
    @abstractmethod
    def closed(self):
        raise NotImplementedError

    @property
    @abstractmethod
    def isEmpty(self):
        raise NotImplementedError