Refactor Solver trait to streamline usage

src/solvers/printing_department.rs

@@ -1,35 +1,21 @@
 use crate::solvers::Solver;
 use grid::*;
-use std::fs::File;
-use std::io;
+use std::io::BufRead;
 
-pub struct PrintingDepartment {
-    part1: u64,
-    part2: u64,
-}
+pub struct PrintingDepartment {}
 
 impl Solver for PrintingDepartment {
-    fn get_puzzle_index(&self) -> u8 {
-        4
-    }
-    fn get_puzzle_name(&self) -> &str {
-        "Printing Department"
-    }
-    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>>) {
+    const PUZZLE_INDEX: u8 = 4;
+    const PUZZLE_NAME: &'static str = "Printing Department";
+    const INPUT_FILENAME: &'static str = "printing_department.txt";
+
+    fn process_data<R: BufRead>(&self, reader: R) -> (u64, u64) {
         let mut grid = Grid::new(0, 0);
-        for line in lines.map_while(Result::ok) {
+        for line in reader.lines().map_while(Result::ok) {
             grid.push_row(line.bytes().map(|c| c == b'@').collect());
         }
 
+        let mut part1 = 0;
         'cells: for cell in grid.indexed_iter() {
             if *cell.1 {
                 let mut count = 0;
@@ -52,14 +38,9 @@ impl Solver for PrintingDepartment {
                         }
                     }
                 }
-                self.part1 += 1;
+                part1 += 1;
             }
         }
-    }
-}
-
-impl PrintingDepartment {
-    pub fn new() -> PrintingDepartment {
-        PrintingDepartment { part1: 0, part2: 0 }
+        (part1, 0)
     }
 }