Move to a solver that takess generic strategies.

src/solver/solver.rs

@@ -0,0 +1,44 @@
+use crate::board::Board;
+use crate::strategy::{NakedSingle, Strategy, StrategyFn};
+use crate::validator;
+
+fn try_strategies(strategies: &[StrategyFn], sudoku_board: &Board) -> Option<Box<dyn Strategy>> {
+    for strategy in strategies {
+        if let Some(strat) = strategy(&sudoku_board) {
+            return Some(strat);
+        }
+    }
+    None
+}
+
+pub fn solve_board(mut sudoku_board: Board) -> Result<Board, Board> {
+    if let validator::BoardState::Broken(ind) = validator::validate_board(&sudoku_board) {
+        println!("{}", sudoku_board.to_url());
+        panic!(
+            "Error invalid number at row {} col {}",
+            (ind / 9) + 1,
+            (ind % 9) + 1
+        );
+    }
+
+    let strategies: [StrategyFn; 1] = [NakedSingle::find_instance];
+
+    while let Some(ns) = try_strategies(&strategies, &sudoku_board) {
+        sudoku_board = ns.apply(sudoku_board);
+
+        if let validator::BoardState::Broken(ind) = validator::validate_board(&sudoku_board) {
+            println!("{}", sudoku_board.to_url());
+            panic!(
+                "Error invalid number at row {} col {}",
+                (ind / 9) + 1,
+                (ind % 9) + 1
+            );
+        }
+    }
+
+    match validator::validate_board(&sudoku_board) {
+        validator::BoardState::Finished => Ok(sudoku_board),
+        validator::BoardState::InProgress => Err(sudoku_board),
+        _ => unreachable!(),
+    }
+}