class ServerNode:
"""A state and transition in the server's history
Attributes:
pos -- the State Object representing this node in state-space
operation -- server.Operation away from this node
"""
def __init__(self, old_node=None):
if old_node is not None:
self.pos = State(old_node.pos)
else:
self.pos = State()
self.operation = None
def append_state_axis(self, client_id):
self.pos.append_state_axis(client_id)
def find_source_of(self, change, remote_id):
"""Finds the node in this list which was the souce of the given change
Params:
change -- a Change object to compare against
remote_id -- the remote that the state is relative to
Returns:
The ServerNode which that change came from
"""
cur_node = self
while (cur_node.pos.get_axis_state(remote_id) != change.src_client_state
or (cur_node.get_rel_server_state(remote_id)
!= change.src_rel_server_state)):
if cur_node.operation is None:
raise "The change did not come from after this node"
cur_node = cur_node.operation.end
return cur_node
def to_csv_cell(self):
return str(self.pos.get_birth_state())
def transform_to_tip(
self,
source_operation,
remote_id):
"""Transforms the operation from this node to the tip, then uses it to
make a new tip
Params:
source_operation -- an operation whose source is this node
remote_id -- the id Number of the remote that caused the change
Returns:
The operation pointing to the new tip of this list
"""
cur_node = self
transformed_op = source_operation
while cur_node.operation is not None:
transformed_op = transformed_op.transform(
end_node=None,
over=cur_node.operation)
cur_node = cur_node.operation.end
# cur_node is now the tip
transformed_op.end = ServerNode(cur_node)
transformed_op.end.pos.increment_state(remote_id)
cur_node.operation = transformed_op
return transformed_op
def make_ack(self, remote_id):
"""Make an Ack object for the remote that made this node"""
return Ack(
client_state=self.pos.get_axis_state(remote_id),
rel_server_state=self.get_rel_server_state(remote_id))
def make_change(self, remote_id):
"""Make a Change object which is consumable by the given remote object
Call on the source of the operation in question.
"""
return Change(
src_client_state=self.pos.get_axis_state(remote_id),
src_rel_server_state=self.get_rel_server_state(remote_id),
op=self.operation.op,
tree_index=self.operation.tree_index,
dest_tree_index=self.operation.dest_tree_index,
linear_index=self.operation.linear_index,
val=self.operation.val,
precedence=self.operation.prec,
index_list=self.operation.index_list)
def get_rel_server_state(self, remote_id):
return self.pos.get_relative_state(remote_id)
