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use std::collections::HashMap; #[test] fn state_change() { use std::rc::Rc; use std::cell::RefCell; struct States; impl States { fn a() -> &'static str { "a" } fn b() -> &'static str { "b" } fn c() -> &'static str { "c" } } struct Log { log: String } impl Log { fn append(&mut self, string: &str) { self.log = self.log.clone() + string; } } let log = Rc::new(RefCell::new(Log { log: String::new() })); let mut state = Stator::new(States::a()); state.add_handler(States::a(), States::b(), |from: &String| { println!("a -> b"); log.borrow_mut().append("1"); }); state.add_handler(Stator::any_state(), States::b(), |from: &String| { println!("? -> b"); log.borrow_mut().append("2"); }); state.add_handler(States::a(), Stator::any_state(), |from: &String| { println!("a -> ?"); log.borrow_mut().append("3"); }); state.add_handler(Stator::any_state(), States::a(), |from: &String| { println!("? -> a"); log.borrow_mut().append("4"); }); state.enter(States::b()); assert!(log.borrow_mut().log == "123", "Unexpected log sequence"); state.enter(States::c()); assert!(log.borrow_mut().log == "123", "Unexpected log sequence"); state.enter(States::b()); assert!(log.borrow_mut().log == "1232", "Unexpected log sequence"); state.enter(States::a()); assert!(log.borrow_mut().log == "12324", "Unexpected log sequence"); } #[derive(Hash, Eq, PartialEq)] struct StatorHashKey { from: String, to: String } pub struct Stator<'a> { current_state: String, state_handlers: HashMap<StatorHashKey, Vec<Box<FnMut(&String) + 'a>>> } impl<'a> Stator<'a> { pub fn any_state() -> &'static str { "_Stator_Internal__Any_State_" } pub fn new(state: &str) -> Stator<'a> { Stator { current_state: state.to_string(), state_handlers: HashMap::new() } } pub fn add_handler<F: FnMut(&String) + 'a>(&mut self, from: &str, to: &str, f: F) { let key = StatorHashKey { from: from.to_string(), to: to.to_string() }; if self.state_handlers.contains_key(&key) { self.state_handlers.get_mut(&key).unwrap().push(Box::new(f)); }else { self.state_handlers.insert(key, vec![Box::new(f)]); } } pub fn enter(&mut self, state: &str) { { let key = StatorHashKey { from: self.current_state.clone(), to: state.to_string() }; if self.state_handlers.contains_key(&key) { let handlers = self.state_handlers.get_mut(&key).unwrap(); for handler in handlers { (*handler)(&self.current_state); } } } { let key = StatorHashKey { from: Stator::any_state().to_string(), to: state.to_string() }; if self.state_handlers.contains_key(&key) { let handlers = self.state_handlers.get_mut(&key).unwrap(); for handler in handlers { (*handler)(&self.current_state); } } } { let key = StatorHashKey { from: self.current_state.clone(), to: Stator::any_state().to_string() }; if self.state_handlers.contains_key(&key) { let handlers = self.state_handlers.get_mut(&key).unwrap(); for handler in handlers { (*handler)(&self.current_state); } } } { let key = StatorHashKey { from: Stator::any_state().to_string(), to: Stator::any_state().to_string() }; if self.state_handlers.contains_key(&key) { let handlers = self.state_handlers.get_mut(&key).unwrap(); for handler in handlers { (*handler)(&self.current_state); } } } self.current_state = state.to_string(); } }