Extract Grid into its own package

2024/src/day4.rs

@@ -1,3 +1,5 @@
+use crate::grid::{Direction, Grid};
+
 const INPUT: &'static str = include_str!("../data/day4.txt");
 
 pub fn day4a() -> String {
@@ -10,50 +12,6 @@ pub fn day4b() -> String {
     format!("{}", find_x_mas(&grid))
 }
 
-struct Grid {
-    width: usize,
-    height: usize,
-    data: Vec<char>,
-}
-
-impl Grid {
-    fn elem(&self, x: usize, y: usize) -> char {
-        if y >= self.height || x >= self.width {
-            panic!("out of range")
-        }
-        self.data[y * self.width + x]
-    }
-}
-
-impl From<&str> for Grid {
-    fn from(input: &str) -> Self {
-        let height = input.lines().count();
-
-        let first_row = input.lines().next().unwrap();
-        let width = first_row.len();
-
-        let data = input.chars().filter(|c| *c != '\n').collect::<Vec<char>>();
-
-        Self {
-            width,
-            height,
-            data,
-        }
-    }
-}
-
-#[derive(Copy, Clone)]
-enum Direction {
-    East,
-    SouthEast,
-    South,
-    SouthWest,
-    West,
-    NorthWest,
-    North,
-    NorthEast,
-}
-
 fn find_xmas(grid: &Grid) -> usize {
     let mut acc = 0;
     for x in 0..grid.width {
@@ -94,7 +52,7 @@ fn check_xmas(grid: &Grid, x: usize, y: usize, direction: Direction) -> bool {
     for c in "XMAS".chars() {
         if let Some((cx, cy)) = addr {
             if grid.elem(cx, cy) == c {
-                addr = move_pointer(grid, cx, cy, direction);
+                addr = grid.move_pointer(cx, cy, direction);
             } else {
                 return false;
             }
@@ -124,10 +82,18 @@ fn check_x_mas(grid: &Grid, x: usize, y: usize) -> bool {
         return false;
     }
 
-    let nw = move_pointer(&grid, x, y, Direction::NorthWest).map(|(cx, cy)| grid.elem(cx, cy));
-    let ne = move_pointer(&grid, x, y, Direction::NorthEast).map(|(cx, cy)| grid.elem(cx, cy));
-    let se = move_pointer(&grid, x, y, Direction::SouthEast).map(|(cx, cy)| grid.elem(cx, cy));
-    let sw = move_pointer(&grid, x, y, Direction::SouthWest).map(|(cx, cy)| grid.elem(cx, cy));
+    let nw = grid
+        .move_pointer(x, y, Direction::NorthWest)
+        .map(|(cx, cy)| grid.elem(cx, cy));
+    let ne = grid
+        .move_pointer(x, y, Direction::NorthEast)
+        .map(|(cx, cy)| grid.elem(cx, cy));
+    let se = grid
+        .move_pointer(x, y, Direction::SouthEast)
+        .map(|(cx, cy)| grid.elem(cx, cy));
+    let sw = grid
+        .move_pointer(x, y, Direction::SouthWest)
+        .map(|(cx, cy)| grid.elem(cx, cy));
 
     match (nw, ne, se, sw) {
         (Some(nw), Some(ne), Some(se), Some(sw)) => {
@@ -165,20 +131,6 @@ fn check_x_mas(grid: &Grid, x: usize, y: usize) -> bool {
     }
 }
 
-fn move_pointer(grid: &Grid, x: usize, y: usize, direction: Direction) -> Option<(usize, usize)> {
-    match direction {
-        Direction::East if x < grid.width - 1 => Some((x + 1, y)),
-        Direction::SouthEast if x < grid.width - 1 && y < grid.height - 1 => Some((x + 1, y + 1)),
-        Direction::South if y < grid.height - 1 => Some((x, y + 1)),
-        Direction::SouthWest if x > 0 && y < grid.height - 1 => Some((x - 1, y + 1)),
-        Direction::West if x > 0 => Some((x - 1, y)),
-        Direction::NorthWest if x > 0 && y > 0 => Some((x - 1, y - 1)),
-        Direction::North if y > 0 => Some((x, y - 1)),
-        Direction::NorthEast if x < grid.width - 1 && y > 0 => Some((x + 1, y - 1)),
-        _ => None,
-    }
-}
-
 #[cfg(test)]
 mod test {
     use super::*;

2024/src/grid.rs

@@ -0,0 +1,59 @@
+pub struct Grid {
+    pub width: usize,
+    pub height: usize,
+    data: Vec<char>,
+}
+
+impl Grid {
+    pub fn elem(&self, x: usize, y: usize) -> char {
+        if y >= self.height || x >= self.width {
+            panic!("out of range")
+        }
+        self.data[y * self.width + x]
+    }
+
+    pub fn move_pointer(&self, x: usize, y: usize, direction: Direction) -> Option<(usize, usize)> {
+        match direction {
+            Direction::East if x < self.width - 1 => Some((x + 1, y)),
+            Direction::SouthEast if x < self.width - 1 && y < self.height - 1 => {
+                Some((x + 1, y + 1))
+            }
+            Direction::South if y < self.height - 1 => Some((x, y + 1)),
+            Direction::SouthWest if x > 0 && y < self.height - 1 => Some((x - 1, y + 1)),
+            Direction::West if x > 0 => Some((x - 1, y)),
+            Direction::NorthWest if x > 0 && y > 0 => Some((x - 1, y - 1)),
+            Direction::North if y > 0 => Some((x, y - 1)),
+            Direction::NorthEast if x < self.width - 1 && y > 0 => Some((x + 1, y - 1)),
+            _ => None,
+        }
+    }
+}
+
+impl From<&str> for Grid {
+    fn from(input: &str) -> Self {
+        let height = input.lines().count();
+
+        let first_row = input.lines().next().unwrap();
+        let width = first_row.len();
+
+        let data = input.chars().filter(|c| *c != '\n').collect::<Vec<char>>();
+
+        Self {
+            width,
+            height,
+            data,
+        }
+    }
+}
+
+#[derive(Copy, Clone)]
+pub enum Direction {
+    East,
+    SouthEast,
+    South,
+    SouthWest,
+    West,
+    NorthWest,
+    North,
+    NorthEast,
+}

2024/src/main.rs

@@ -4,6 +4,7 @@ mod day3;
 mod day4;
 mod day5;
 mod day6;
+mod grid;
 
 fn main() {
     let day = std::env::args().skip(1).next();