Refactor Solver trait to streamline usage

src/solvers.rs

@@ -8,52 +8,53 @@ pub mod printing_department;
 pub mod trash_compactor;
 
 pub trait Solver {
-    fn get_puzzle_index(&self) -> u8;
-    fn get_puzzle_name(&self) -> &str;
-    fn get_input_filename(&self) -> &str;
-    fn get_part1(&self) -> u64;
-    fn get_part2(&self) -> u64;
-    fn process_data(&mut self, lines: io::Lines<io::BufReader<File>>);
+    const PUZZLE_INDEX: u8;
+    const PUZZLE_NAME: &'static str;
+    // TODO: Replace constant input filename by a conversion from the puzzle name in the runner.
+    const INPUT_FILENAME: &'static str;
+
+    fn puzzle_index(&self) -> u8 { Self::PUZZLE_INDEX }
+    fn puzzle_name(&self) -> &'static str { Self::PUZZLE_NAME }
+    fn input_filename(&self) -> &'static str { Self::INPUT_FILENAME }
+
+    fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64);
 }
 
-pub fn run(mut solver: Box<dyn Solver>) {
+pub fn run<S: Solver>(solver: S) {
     println!(
         "--- Day {}: {} ---",
-        solver.get_puzzle_index(),
-        solver.get_puzzle_name()
+        solver.puzzle_index(),
+        solver.puzzle_name()
     );
 
+    // TODO: Convert to constant and add "example" paths.
     // The "../../data" and "../../../data" paths are useful for running the binary from
     // "target/release/" directory with "data/" directory in package root or parent directory.
     let paths = vec!["./data", "../data", "../../data", "../../../data"];
 
-    match read_data_file(solver.get_input_filename(), &paths) {
-        Ok(lines) => {
-            solver.process_data(lines);
-            print_result(solver);
+    match read_data_file(solver.input_filename(), &paths) {
+        Ok(reader) => {
+            let result = solver.process_data(reader);
+            print_result(result);
         }
         Err(error) => eprintln!("{}", error),
     };
 }
 
-fn print_result(solver: Box<dyn Solver>) {
-    println!(
-        "Part 1: {:?}\nPart 2: {:?}\n",
-        solver.get_part1(),
-        solver.get_part2()
-    );
+fn print_result(result: (u64, u64)) {
+    println!("Part 1: {:?}\nPart 2: {:?}\n", result.0, result.1);
 }
 
 fn read_data_file<T>(
     filename: T,
     search_paths: &Vec<T>,
-) -> Result<io::Lines<io::BufReader<File>>, String>
+) -> Result<io::BufReader<File>, String>
 where
     T: AsRef<Path>,
 {
     for path in search_paths {
-        if let Ok(lines) = read_lines(path.as_ref().join(&filename)) {
-            return Ok(lines);
+        if let Ok(reader) = read_file(path.as_ref().join(&filename)) {
+            return Ok(reader);
         }
     }
 
@@ -69,10 +70,10 @@ where
 }
 
 // This code is taken from https://doc.rust-lang.org/stable/rust-by-example/std_misc/file/read_lines.html
-fn read_lines<T>(filename: T) -> io::Result<io::Lines<io::BufReader<File>>>
+fn read_file<T>(filename: T) -> io::Result<io::BufReader<File>>
 where
     T: AsRef<Path>,
 {
     let file = File::open(filename)?;
-    Ok(io::BufReader::new(file).lines())
+    Ok(io::BufReader::new(file))
 }