sirosen/SALVE

from salve.action.base import Action


class ActionList(Action):
    """
    An ActionList, often referred to internally as an "AL", is one of
    the basic Action types.

    It is used to provide a sequential list of other actions to execute.
    """
    def __init__(self, act_lst, file_context):
        """
        ActionList constructor.

        Args:
            @act_list
            A list of Action objects. No checking is performed, the
            class assumes that what it is handed is in fact a list of
            Action objects.

            @file_context
            The FileContext.
        """
        Action.__init__(self, file_context)
        self.actions = act_lst

    def __iter__(self):
        """
        Iterating over an AL iterates over its sub-actions.
        """
        for act in self.actions:
            yield act

    def __str__(self):
        return ("ActionList([" +
                ",".join(str(a) for a in self.actions) +
                "],context=" + repr(self.file_context) + ")")

    def append(self, act):
        """
        Append a new Action to the AL.

        Args:
            @act
            The action to append.
        """
        assert isinstance(act, Action)
        self.actions.append(act)

    def prepend(self, act):
        """
        Prepend a new Action to the AL.

        Args:
            @act
            The action to prepend.
        """
        assert isinstance(act, Action)
        self.actions.insert(0, act)

    def execute(self, filesys):
        """
        Execute the AL. Consists of a walk over the AL executing each
        of its sub-actions.

        Args:
            @filesys
            The filesystem on which the action should be executed. Used to
            transition actions between operation on the real and virtualized
            filesystem.
        """
        for act in self:
            act(filesys)