Implement day 1 2018.

We've started.

2018/src/main.rs

@@ -4,14 +4,13 @@ use std::fs;
 use std::io;
 
 pub mod common;
-pub mod day1;
+pub mod day01;
 
-fn get_impl(day: i32) -> Box<common::Solution> {
-    match day {
-        1 => { Box::new(day1::Day1::new()) }
-        _ => {
-            panic!("Unimplemented day {}", day)
-        }
+fn get_impl(day: &str) -> Box<common::Solution> {
+    match day.parse() {
+        Ok(1) => { Box::new(day01::Day01::new()) }
+        Ok(val) => panic!("Unimplemented day {}", val),
+        _ => panic!("Invalid number"),
     }
 }
 
@@ -35,9 +34,7 @@ fn main() {
              .takes_value(true))
         .get_matches();
 
-    let day: i32 = (&matches.value_of("day").unwrap()).parse()
-        .expect("Invalid int");
-    let mut implementation = get_impl(day);
+    let mut implementation = get_impl(matches.value_of("day").unwrap());
     let mut data: Box<io::Read> = match matches.value_of("input") {
         Some(filename) => { Box::new(fs::File::open(filename).unwrap()) }
         None => { Box::new(io::stdin()) }
@@ -59,7 +56,7 @@ mod tests {
         // Verify that we can load all days
         let last_implemented = 1;
         for d in 1..(last_implemented + 1) {
-            get_impl(d);
+            get_impl(&format!("{}", d));
         }
     }
 }