1 files changed, 54 insertions, 19 deletions
diff --git a/src/2021/2/mod.rs b/src/2021/2/mod.rs
index e175ab9..6cac620 100644
--- a/src/2021/2/mod.rs
+++ b/src/2021/2/mod.rs
@@ -1,31 +1,60 @@
-pub fn part1() -> anyhow::Result<i64> {
-    let mut horizontal = 0;
-    let mut vertical = 0;
-    for line in data_lines!()? {
+pub enum Command {
+    Forward(i64),
+    Down(i64),
+    Up(i64),
+}
+
+pub fn parse(
+    fh: std::fs::File,
+) -> anyhow::Result<impl Iterator<Item = Command>> {
+    Ok(crate::util::parse::lines(fh).map(|line| {
         if let Some(n) = line.strip_prefix("forward ") {
-            horizontal += n.parse::<i64>()?;
+            Command::Forward(n.parse().unwrap())
         } else if let Some(n) = line.strip_prefix("down ") {
-            vertical += n.parse::<i64>()?;
+            Command::Down(n.parse().unwrap())
         } else if let Some(n) = line.strip_prefix("up ") {
-            vertical -= n.parse::<i64>()?;
+            Command::Up(n.parse().unwrap())
+        } else {
+            panic!("couldn't parse line: {}", line);
+        }
+    }))
+}
+
+pub fn part1(commands: impl Iterator<Item = Command>) -> anyhow::Result<i64> {
+    let mut horizontal = 0;
+    let mut vertical = 0;
+    for command in commands {
+        match command {
+            Command::Forward(n) => {
+                horizontal += n;
+            }
+            Command::Down(n) => {
+                vertical += n;
+            }
+            Command::Up(n) => {
+                vertical -= n;
+            }
         }
     }
     Ok(horizontal * vertical)
 }
 
-pub fn part2() -> anyhow::Result<i64> {
+pub fn part2(commands: impl Iterator<Item = Command>) -> anyhow::Result<i64> {
     let mut aim = 0;
     let mut horizontal = 0;
     let mut vertical = 0;
-    for line in data_lines!()? {
-        if let Some(n) = line.strip_prefix("forward ") {
-            let x = n.parse::<i64>()?;
-            horizontal += x;
-            vertical += aim * x;
-        } else if let Some(n) = line.strip_prefix("down ") {
-            aim += n.parse::<i64>()?;
-        } else if let Some(n) = line.strip_prefix("up ") {
-            aim -= n.parse::<i64>()?;
+    for command in commands {
+        match command {
+            Command::Forward(n) => {
+                horizontal += n;
+                vertical += aim * n;
+            }
+            Command::Down(n) => {
+                aim += n;
+            }
+            Command::Up(n) => {
+                aim -= n;
+            }
         }
     }
     Ok(horizontal * vertical)
@@ -33,6 +62,12 @@ pub fn part2() -> anyhow::Result<i64> {
 
 #[test]
 fn test() {
-    assert_eq!(part1().unwrap(), 1694130);
-    assert_eq!(part2().unwrap(), 1698850445);
+    assert_eq!(
+        part1(parse(crate::util::data(2021, 2).unwrap()).unwrap()).unwrap(),
+        1694130
+    );
+    assert_eq!(
+        part2(parse(crate::util::data(2021, 2).unwrap()).unwrap()).unwrap(),
+        1698850445
+    );
 }