Internal tweaks

src/agents/util/partials.rs

@@ -8,14 +8,21 @@ use crate::{board::Board, util::Symb};
 /// - coords are the coordinate of this slot's partial
 /// - char_idx is the index of this slot in its partial
 /// - f32 is the influence of this slot
-pub fn free_slots_by_influence(board: &Board) -> Vec<(usize, f32)> {
+pub fn free_slots_by_influence(board: &Board) -> Option<Vec<(usize, f32)>> {
 	// Fill all empty slots with fives and compute starting value
-	let filled = Board::from_board(board.get_board().map(|x| match x {
-		None => Symb::from_char('5'),
-		_ => x,
-	}));
+	let filled = {
+		// This should always result in an evaluatable expression,
+		// since parenthesis do not exist.
+		// (the only way to divide by zero is by doing something like /(5-2+3) )
+		let f = Board::from_board(board.get_board().map(|x| match x {
+			None => Symb::from_char('5'),
+			_ => x,
+		}));
 
-	let base = filled.evaluate().unwrap();
+		f
+	};
+
+	let base = filled.evaluate()?;
 
 	// Test each slot:
 	// Increase its value by 1, and record its effect on the
@@ -36,13 +43,17 @@ pub fn free_slots_by_influence(board: &Board) -> Vec<(usize, f32)> {
 		.collect();
 
 	// Sort by most to least influence
-	slots.sort_by(|a, b| b.1.abs().partial_cmp(&a.1.abs()).unwrap());
-	slots
+	slots.sort_by(|a, b| {
+		b.1.abs()
+			.partial_cmp(&a.1.abs())
+			.unwrap_or(std::cmp::Ordering::Equal)
+	});
+	Some(slots)
 }
 
 /// Find the maximum possible value of the given board
 #[allow(dead_code)]
-pub fn maximize_value(board: &Board) -> Board {
+pub fn maximize_value(board: &Board) -> Option<Board> {
 	let n_free = board.get_board().iter().filter(|x| x.is_none()).count();
 
 	// Assume we have 10 or fewer available slots
@@ -58,7 +69,7 @@ pub fn maximize_value(board: &Board) -> Board {
 		.filter(|x| !board.contains(*x))
 		.collect::<Vec<_>>();
 
-	let slots = free_slots_by_influence(&board);
+	let slots = free_slots_by_influence(&board)?;
 
 	let all_symbols = {
 		// We need this many from the bottom, and this many from the top.
@@ -125,5 +136,5 @@ pub fn maximize_value(board: &Board) -> Board {
 		}
 	}
 
-	best_board.unwrap()
+	best_board
 }