better iter order

card_game/src/lib.rs

@@ -6,10 +6,10 @@ struct ReadmeDoctests;
 use core::ops::RangeBounds;
 
 // TODO: pub struct ValidInstruction<I>(I);
-pub trait Game {
+pub trait Game: Clone + core::fmt::Debug {
-	type Stats;
+	type Stats: Clone + core::fmt::Debug;
-	type Config;
+	type Config: Clone + core::fmt::Debug;
-	type Instruction;
+	type Instruction: Clone + core::fmt::Debug;
 	fn possible_instructions(&self) -> impl Iterator<Item = Self::Instruction> + use<Self>;
 	fn is_instruction_valid(&self, config: &Self::Config, instruction: Self::Instruction) -> bool;
 	fn process_instruction(
@@ -321,32 +321,33 @@ impl<S> SessionStats<S> {
 	}
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
-pub struct Session<G: Game>
+pub struct Session<G: Game> {
-where
-	G::Config: Clone,
-	G::Instruction: Clone,
-{
 	stats: SessionStats<G::Stats>,
 	config: G::Config,
 	state: SessionState<G>,
 }
-#[derive(Clone, Eq, Hash, PartialEq)]
+#[derive(Clone, Debug)]
-pub struct SessionState<G: Game>
+pub struct StateSnapshot<G: Game> {
-where
-	G::Instruction: Clone,
-{
-	seed: G,
 	state: G,
-	history: Vec<G::Instruction>,
+	instruction: G::Instruction,
 }
-impl<G: Game + Clone> SessionState<G>
+impl<G: Game> StateSnapshot<G> {
-where
+	pub const fn state(&self) -> &G {
-	G::Instruction: Clone,
+		&self.state
-{
+	}
+	pub const fn instruction(&self) -> &G::Instruction {
+		&self.instruction
+	}
+}
+#[derive(Clone, Debug)]
+pub struct SessionState<G: Game> {
+	state: G,
+	history: Vec<StateSnapshot<G>>,
+}
+impl<G: Game + Clone> SessionState<G> {
 	fn new(state: G) -> Self {
 		Self {
-			seed: state.clone(),
 			state,
 			history: Vec::new(),
 		}
@@ -381,7 +382,7 @@ where
 	pub const fn config(&self) -> &G::Config {
 		&self.config
 	}
-	pub fn history(&self) -> &[G::Instruction] {
+	pub fn history(&self) -> &[StateSnapshot<G>] {
 		&self.state.history
 	}
 	pub fn undo(&mut self) {
@@ -401,9 +402,10 @@ where
 	pub fn is_win(&self) -> bool {
 		self.state.is_win()
 	}
-	pub fn is_winnable(&self) -> Option<Vec<G::Instruction>> {
+	pub fn is_winnable(&self) -> Option<Vec<StateSnapshot<G>>> {
 		let mut state_moves = std::collections::HashMap::new();
 		let mut state = self.clone();
+		let mut i: u64 = 0;
 		while !state.is_win() {
 			// Continue existing iterator if it exists
 			let it = state_moves
@@ -423,14 +425,39 @@ where
 				state.undo();
 			}
 		}
+
+		// history includes cycles
+		let mut state_index: std::collections::HashMap<_, _> = state
+			.history()
+			.iter()
+			.enumerate()
+			.map(|(i, snapshot)| (snapshot.state().clone(), i))
+			.collect();
+
+		// find the longest range where the start and end are the same state
+		while let Some(longest_range) = state
+			.history()
+			.iter()
+			.enumerate()
+			.filter_map(|(index, snapshot)| {
+				let &last_index = state_index.get(snapshot.state())?;
+				let longness = last_index - index;
+				(longness != 0).then_some(index..last_index)
+			})
+			.max_by_key(|range| range.len())
+		{
+			state.state.history.drain(longest_range);
+			for (i, snapshot) in state.history().iter().enumerate() {
+				state_index.insert(snapshot.state().clone(), i);
+			}
+		}
+
 		Some(state.state.history)
 	}
 }
 impl<G: Game> Game for SessionState<G>
 where
-	G: Clone,
 	G::Stats: Default,
-	G::Instruction: Clone,
 {
 	type Stats = SessionStats<G::Stats>;
 	type Config = G::Config;
@@ -456,19 +483,16 @@ where
 	) {
 		match instruction {
 			SessionInstruction::Undo => {
-				// replay the entire history of the game except one move
+				if let Some(snapshot) = self.history.pop() {
-				self.history.pop();
+					self.state = snapshot.state;
-				let mut inner_stats = G::Stats::default();
+					stats.increment_undos();
-				let mut state = self.seed.clone();
-				for instruction in &self.history {
-					state.process_instruction(&mut inner_stats, config, instruction.clone());
 				}
-				self.state = state;
-				stats.inner_stats = inner_stats;
-				stats.increment_undos();
 			}
 			SessionInstruction::InnerInstruction(instruction) => {
-				self.history.push(instruction.clone());
+				self.history.push(StateSnapshot {
+					state: self.state.clone(),
+					instruction: instruction.clone(),
+				});
 				self.state
 					.process_instruction(&mut stats.inner_stats, config, instruction);
 			}

klondike-cli/src/test.rs

@@ -3,31 +3,13 @@ use klondike::Klondike;
 #[test]
 fn test_is_winnable() {
 	// is winnable
-	let is_winnable = Session::new_default(Klondike::with_seed(123)).is_winnable();
+	let is_winnable = Session::new_default(Klondike::with_seed(124)).is_winnable();
-	println!("is_winnable = {is_winnable:?}");
+	if let Some(win_moves) = is_winnable {
-}
+		// for (i, ins) in win_moves.into_iter().enumerate() {
-#[test]
+		// 	println!("{i} = {:?}", ins.instruction());
-fn test_klondike() {
+		// }
-	// create game session
+		println!("Game is winnable with {} moves", win_moves.len());
-	let game = Klondike::with_seed(123);
+	} else {
-	let mut session = Session::new_default(game);
+		println!("Game is not winnable");
-
-	// is winnable
-	let is_winnable = session.is_winnable();
-	println!("is_winnable = {is_winnable:?}");
-
-	// play game
-	while let Some(instruction) = session.possible_instructions().next() {
-		session.process_instruction(instruction);
 	}
-
-	// did win
-	let is_win = session.is_win();
-
-	// print session history
-	for (i, instruction) in session.history().iter().enumerate() {
-		println!("move {i} = {instruction:?}");
-	}
-
-	println!("is_win = {is_win}");
 }

klondike/src/lib.rs

@@ -533,6 +533,10 @@ impl Iterator for KlondikeIter {
 		instruction
 	}
 }
+#[test]
+fn test_klondike_iter() {
+	assert_eq!(KlondikeIter::new().count(), 721);
+}
 
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 pub struct Klondike {
@@ -625,18 +629,19 @@ impl Klondike {
 			KlondikeInstruction::RotateStock => 4,
 		}
 	}
+	pub fn iter(&self) -> impl Iterator<Item = KlondikeInstruction> + use<> {
+		let state = self.state.clone();
+		KlondikeIter::new().filter(move |&instruction| state.is_instruction_valid(instruction))
+	}
 	/// A single move that usually makes progress towards a winning game
 	pub fn get_auto_move(&self) -> Option<KlondikeInstruction> {
-		self.possible_instructions()
+		self.iter()
 			.filter(|ins| !ins.is_useless())
 			.min_by_key(|ins| self.instruction_priority(ins))
 	}
 	/// A list of possible moves with useless moves filtered out and sorted by a simple priority function
 	pub fn get_sorted_moves(&self) -> Vec<KlondikeInstruction> {
-		let mut useful_moves: Vec<_> = self
+		let mut useful_moves: Vec<_> = self.iter().filter(|ins| !ins.is_useless()).collect();
-			.possible_instructions()
-			.filter(|ins| !ins.is_useless())
-			.collect();
 		useful_moves.sort_by_key(|ins| self.instruction_priority(ins));
 		useful_moves
 	}
@@ -647,8 +652,7 @@ impl Game for Klondike {
 	type Config = KlondikeConfig;
 	type Instruction = KlondikeInstruction;
 	fn possible_instructions(&self) -> impl Iterator<Item = Self::Instruction> + use<> {
-		let state = self.state.clone();
+		self.get_sorted_moves().into_iter()
-		KlondikeIter::new().filter(move |&instruction| state.is_instruction_valid(instruction))
 	}
 	fn is_instruction_valid(&self, _config: &Self::Config, instruction: Self::Instruction) -> bool {
 		self.state.is_instruction_valid(instruction)