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[modified] minor semantics of state machines, added machinery to allow them to be nested more easily, added notes
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@ -12,6 +12,10 @@
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on draw, the current state's draw callback is called
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TODO: consider coroutine friendliness
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TODO: consider refactoring the callback signatures to allow using objects with methods
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like update(dt)/draw() directly
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current pattern means they need to be wrapped (as in :as_state())
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]]
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local path = (...):gsub("state_machine", "")
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@ -41,12 +45,27 @@ end
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--make an internal call
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function state_machine:_call(name, ...)
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local state = self:_get_state()
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if state and type(state[name]) == "function" then
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return state[name](self, state, ...)
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if state then
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if type(state[name]) == "function" then
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return state[name](self, state, ...)
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elseif type(state) == "function" then
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return state(self, name, ...)
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end
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end
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return nil
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end
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--make an internal call and transition if the return value is a valid state
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--return the value if it isn't a valid state
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function state_machine:_call_and_transition(name, ...)
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local r = self:_call(name, ...)
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if self:has_state(r) then
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self:set_state(r, r == self.current_state)
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return nil
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end
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return r
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end
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-------------------------------------------------------------------------------
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--various checks
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@ -63,7 +82,7 @@ end
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--add a state
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function state_machine:add_state(name, data)
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if self.has_state(name) then
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if self:has_state(name) then
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error("error: added duplicate state "..name)
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else
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self.states[name] = data
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@ -77,7 +96,7 @@ end
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--remove a state
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function state_machine:remove_state(name)
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if not self.has_state(name) then
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if not self:has_state(name) then
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error("error: removed missed state "..name)
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else
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if self:in_state(name) then
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@ -99,13 +118,13 @@ function state_machine:replace_state(name, data, do_transitions)
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end
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self.states[name] = data
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if do_transitions and current then
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self:_call("enter")
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self:_call_and_transition("enter")
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end
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return self
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end
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--ensure a state doesn't exist
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--ensure a state doesn't exist; transition out of it if we're currently in it
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function state_machine:clear_state(name)
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return self:replace_state(name, nil, true)
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end
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@ -113,23 +132,52 @@ end
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-------------------------------------------------------------------------------
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--transitions and updates
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--set the current state
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--if the enter callback of the target state returns a valid state name, then
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-- it is transitioned to in turn, and so on until the machine is at rest
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function state_machine:set_state(state, reset)
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if self.current_state ~= state or reset then
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self:_call("exit")
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self.current_state = state
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self:_call("enter")
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self:_call_and_transition("enter")
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end
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return self
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end
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--perform an update
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--pass in an optional delta time which is passed as an arg to the state functions
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--if the state update returns a string, and we have that state
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-- then we change state (reset if it's the current state)
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-- and return nil
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--otherwise, the result is returned
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function state_machine:update(dt)
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return self:_call("update", dt)
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return self:_call_and_transition("update", dt)
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end
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--draw the current state
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function state_machine:draw()
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self:_call("draw")
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end
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return state_machine
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--wrap a state machine in a table suitable for use directly as a state in another state_machine
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--upon entry, this machine will be forced into enter_state
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--the parent will be accessible under m.parent
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function state_machine:as_state(enter_state)
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if not self._as_state then
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self._as_state = {
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enter = function(m, s)
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self.parent = m
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self:set_state(enter_state)
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end,
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update = function(m, s, dt)
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return self:update(dt)
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end,
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draw = function(m, s)
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return self:draw()
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end,
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}
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end
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return self._as_state
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end
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return state_machine
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