Add Solver trait and move common functionality out of concrete solvers

src/main.rs

@@ -1,8 +1,10 @@
-mod solvers;
 mod common;
+mod solvers;
 
 fn main() {
     println!("### Advent of Code 2025 ###\n");
-    solvers::printing_department::PrintingDepartment::new().run();
+    solvers::run(Box::new(
-    solvers::cafeteria::Cafeteria::new().run();
+        solvers::printing_department::PrintingDepartment::new(),
+    ));
+    solvers::run(Box::new(solvers::cafeteria::Cafeteria::new()));
 }

src/solvers.rs

@@ -1,2 +1,77 @@
+use std::fs::File;
+use std::io;
+use std::io::BufRead;
+use std::path::Path;
+
 pub mod cafeteria;
 pub mod printing_department;
+
+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>>);
+}
+
+pub fn run(mut solver: Box<dyn Solver>) {
+    println!(
+        "--- Day {}: {} ---",
+        solver.get_puzzle_index(),
+        solver.get_puzzle_name()
+    );
+
+    // 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);
+        }
+        Err(error) => eprintln!("{}", error),
+    };
+}
+
+fn print_result(solver: Box<dyn Solver>) {
+    println!(
+        "Part 1: {:?}\nPart 2: {:?}\n",
+        solver.get_part1(),
+        solver.get_part2()
+    );
+}
+
+fn read_data_file<T>(
+    filename: T,
+    search_paths: &Vec<T>,
+) -> Result<io::Lines<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);
+        }
+    }
+
+    let message = search_paths
+        .iter()
+        .map(|path| path.as_ref().join(&filename).display().to_string())
+        .collect::<Vec<_>>()
+        .join("\n");
+    Err(format!(
+        "Cannot open puzzle input file, searched these paths:\n{}",
+        message
+    ))
+}
+
+// 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>>>
+where
+    T: AsRef<Path>,
+{
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}

src/solvers/cafeteria.rs

@@ -1,36 +1,30 @@
 use crate::common::interval::Interval;
+use crate::solvers::Solver;
 use std::collections::BTreeSet;
 use std::fs::File;
 use std::io;
-use std::io::BufRead;
-use std::path::Path;
 
 pub struct Cafeteria {
     part1: u64,
     part2: u64,
 }
 
-impl Cafeteria {
+impl Solver for Cafeteria {
-    pub fn new() -> Cafeteria {
+    fn get_puzzle_index(&self) -> u8 {
-        Cafeteria { part1: 0, part2: 0 }
+        5
     }
-
+    fn get_puzzle_name(&self) -> &str {
-    pub fn run(&mut self) {
+        "Cafeteria"
-        println!("--- Day 5: Cafeteria ---");
-
-        // 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("cafeteria.txt", &paths) {
-            Ok(lines) => {
-                self.process_data(lines);
-                self.print_result();
     }
-            Err(error) => eprintln!("{}", error),
+    fn get_input_filename(&self) -> &str {
-        };
+        "cafeteria.txt"
+    }
+    fn get_part1(&self) -> u64 {
+        self.part1
+    }
+    fn get_part2(&self) -> u64 {
+        self.part2
     }
-
     fn process_data(&mut self, mut lines: io::Lines<io::BufReader<File>>) {
         // Builds intervals collection.
         let mut intervals: BTreeSet<Interval> = BTreeSet::new();
@@ -83,41 +77,10 @@ impl Cafeteria {
 
         self.part2 = intervals.iter().map(|x| x.len()).sum();
     }
-
-    fn print_result(&self) {
-        println!("Part 1: {:?}\nPart 2: {:?}\n", self.part1, self.part2);
-    }
 }
 
-fn read_data_file<T>(
+impl Cafeteria {
-    filename: T,
+    pub fn new() -> Cafeteria {
-    search_paths: &Vec<T>,
+        Cafeteria { part1: 0, part2: 0 }
-) -> Result<io::Lines<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);
     }
 }
-
-    let message = search_paths
-        .iter()
-        .map(|path| path.as_ref().join(&filename).display().to_string())
-        .collect::<Vec<_>>()
-        .join("\n");
-    Err(format!(
-        "Cannot open puzzle input file, searched these paths:\n{}",
-        message
-    ))
-}
-
-// 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>>>
-where
-    T: AsRef<Path>,
-{
-    let file = File::open(filename)?;
-    Ok(io::BufReader::new(file).lines())
-}

src/solvers/printing_department.rs

@@ -1,35 +1,29 @@
+use crate::solvers::Solver;
 use grid::*;
 use std::fs::File;
 use std::io;
-use std::io::BufRead;
-use std::path::Path;
 
 pub struct PrintingDepartment {
     part1: u64,
     part2: u64,
 }
 
-impl PrintingDepartment {
+impl Solver for PrintingDepartment {
-    pub fn new() -> PrintingDepartment {
+    fn get_puzzle_index(&self) -> u8 {
-        PrintingDepartment { part1: 0, part2: 0 }
+        4
     }
-
+    fn get_puzzle_name(&self) -> &str {
-    pub fn run(&mut self) {
+        "Printing Department"
-        println!("--- Day 4: Printing Department ---");
-
-        // 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("printing_department.txt", &paths) {
-            Ok(lines) => {
-                self.process_data(lines);
-                self.print_result();
     }
-            Err(error) => eprintln!("{}", error),
+    fn get_input_filename(&self) -> &str {
-        };
+        "printing_department.txt"
+    }
+    fn get_part1(&self) -> u64 {
+        self.part1
+    }
+    fn get_part2(&self) -> u64 {
+        self.part2
     }
-
     fn process_data(&mut self, lines: io::Lines<io::BufReader<File>>) {
         let mut grid = Grid::new(0, 0);
         for line in lines.map_while(Result::ok) {
@@ -62,41 +56,10 @@ impl PrintingDepartment {
             }
         }
     }
-
-    fn print_result(&self) {
-        println!("Part 1: {:?}\nPart 2: {:?}\n", self.part1, self.part2);
-    }
 }
 
-fn read_data_file<T>(
+impl PrintingDepartment {
-    filename: T,
+    pub fn new() -> PrintingDepartment {
-    search_paths: &Vec<T>,
+        PrintingDepartment { part1: 0, part2: 0 }
-) -> Result<io::Lines<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);
     }
 }
-
-    let message = search_paths
-        .iter()
-        .map(|path| path.as_ref().join(&filename).display().to_string())
-        .collect::<Vec<_>>()
-        .join("\n");
-    Err(format!(
-        "Cannot open puzzle input file, searched these paths:\n{}",
-        message
-    ))
-}
-
-// 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>>>
-where
-    T: AsRef<Path>,
-{
-    let file = File::open(filename)?;
-    Ok(io::BufReader::new(file).lines())
-}