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local events = require "util.events";
local fsm_methods = {};
local fsm_mt = { __index = fsm_methods };
local function is_fsm(o)
local mt = getmetatable(o);
return mt == fsm_mt;
end
local function notify_transition(fire_event, transition_event)
local ret;
ret = fire_event("transition", transition_event);
if ret ~= nil then return ret; end
if transition_event.from ~= transition_event.to then
ret = fire_event("leave/"..transition_event.from, transition_event);
if ret ~= nil then return ret; end
end
ret = fire_event("transition/"..transition_event.name, transition_event);
if ret ~= nil then return ret; end
end
local function notify_transitioned(fire_event, transition_event)
if transition_event.to ~= transition_event.from then
fire_event("enter/"..transition_event.to, transition_event);
end
if transition_event.name then
fire_event("transitioned/"..transition_event.name, transition_event);
end
fire_event("transitioned", transition_event);
end
local function do_transition(name)
return function (self, attr)
local new_state = self.fsm.states[self.state][name] or self.fsm.states["*"][name];
if not new_state then
return error(("Invalid state transition: %s cannot %s"):format(self.state, name));
end
local transition_event = {
instance = self;
name = name;
to = new_state;
to_attr = attr;
from = self.state;
from_attr = self.state_attr;
};
local fire_event = self.fsm.events.fire_event;
local ret = notify_transition(fire_event, transition_event);
if ret ~= nil then return nil, ret; end
self.state = new_state;
self.state_attr = attr;
notify_transitioned(fire_event, transition_event);
return true;
end;
end
local function new(desc)
local self = setmetatable({
default_state = desc.default_state;
events = events.new();
}, fsm_mt);
-- states[state_name][transition_name] = new_state_name
local states = { ["*"] = {} };
if desc.default_state then
states[desc.default_state] = {};
end
self.states = states;
local instance_methods = {};
self._instance_mt = { __index = instance_methods };
for _, transition in ipairs(desc.transitions or {}) do
local from_states = transition.from;
if type(from_states) ~= "table" then
from_states = { from_states };
end
for _, from in ipairs(from_states) do
if not states[from] then
states[from] = {};
end
if not states[transition.to] then
states[transition.to] = {};
end
if states[from][transition.name] then
return error(("Duplicate transition in FSM specification: %s from %s"):format(transition.name, from));
end
states[from][transition.name] = transition.to;
end
-- Add public method to trigger this transition
instance_methods[transition.name] = do_transition(transition.name);
end
if desc.state_handlers then
for state_name, handler in pairs(desc.state_handlers) do
self.events.add_handler("enter/"..state_name, handler);
end
end
if desc.transition_handlers then
for transition_name, handler in pairs(desc.transition_handlers) do
self.events.add_handler("transition/"..transition_name, handler);
end
end
if desc.handlers then
self.events.add_handlers(desc.handlers);
end
return self;
end
function fsm_methods:init(state_name, state_attr)
local initial_state = assert(state_name or self.default_state, "no initial state specified");
if not self.states[initial_state] then
return error("Invalid initial state: "..initial_state);
end
local instance = setmetatable({
fsm = self;
state = initial_state;
state_attr = state_attr;
}, self._instance_mt);
if initial_state ~= self.default_state then
local fire_event = self.events.fire_event;
notify_transitioned(fire_event, {
instance = instance;
to = initial_state;
to_attr = state_attr;
from = self.default_state;
});
end
return instance;
end
function fsm_methods:is_instance(o)
local mt = getmetatable(o);
return mt == self._instance_mt;
end
return {
new = new;
is_fsm = is_fsm;
};
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