Merge owned and non-owned grids

Through the power of generics. Should've been easier if it was possible
to be generic over mutable and non-mutable, but AsRef/AsMut is close
enough

2023/src/common.rs

@@ -244,20 +244,22 @@ impl IndexMut<usize> for Vec2 {
     }
 }
 
-pub struct Grid<'a> {
+#[derive(PartialEq)]
+pub struct Grid<T: AsRef<[u8]>> {
     width: usize,
-    data: &'a [u8],
+    data: T,
 }
 
-impl<'a> Grid<'a> {
+impl<T: AsRef<[u8]>> Grid<T> {
-    pub fn new(data: &'a [u8]) -> anyhow::Result<Self> {
+    pub fn new(data: T) -> anyhow::Result<Self> {
         let width = 1 + data
+            .as_ref()
             .iter()
             .position(|&c| c == b'\n')
             .context("Failed to find end of line in grid")?;
 
         anyhow::ensure!(
-            data.len() % width == 0,
+            data.as_ref().len() % width == 0,
             "Grid should divide equally into rows"
         );
 
@@ -265,65 +267,7 @@ impl<'a> Grid<'a> {
     }
 
     pub fn height(&self) -> usize {
-        self.data.len() / self.width
+        self.data.as_ref().len() / self.width
-    }
-
-    pub fn width(&self) -> usize {
-        self.width - 1
-    }
-
-    pub fn rows(&self) -> impl Iterator<Item = &'a [u8]> {
-        let width = self.width();
-        self.data
-            .chunks_exact(self.width)
-            .map(move |row| &row[..width])
-    }
-
-    pub fn find(&self, c: u8) -> Option<(usize, usize)> {
-        let pos = self.data.iter().position(|&d| d == c)?;
-
-        Some((pos % self.width, pos / self.width))
-    }
-}
-
-impl<'a> Index<usize> for Grid<'a> {
-    type Output = [u8];
-
-    fn index(&self, y: usize) -> &Self::Output {
-        let offset = y * self.width;
-        &self.data[offset..(offset + self.width())]
-    }
-}
-
-impl Display for Grid<'_> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", String::from_utf8_lossy(self.data))
-    }
-}
-
-// TODO: merge OwnedGrid and Grid impls so I don't go insane
-pub struct OwnedGrid {
-    width: usize,
-    data: Vec<u8>,
-}
-
-impl OwnedGrid {
-    pub fn new(data: Vec<u8>) -> anyhow::Result<Self> {
-        let width = 1 + data
-            .iter()
-            .position(|&c| c == b'\n')
-            .context("Failed to find end of line in grid")?;
-
-        anyhow::ensure!(
-            data.len() % width == 0,
-            "Grid should divide equally into rows"
-        );
-
-        Ok(Self { width, data })
-    }
-
-    pub fn height(&self) -> usize {
-        self.data.len() / self.width
     }
 
     pub fn width(&self) -> usize {
@@ -333,59 +277,48 @@ impl OwnedGrid {
     pub fn rows(&self) -> impl Iterator<Item = &[u8]> {
         let width = self.width();
         self.data
+            .as_ref()
             .chunks_exact(self.width)
             .map(move |row| &row[..width])
     }
 
-    pub fn rows_mut(&mut self) -> impl Iterator<Item = &mut [u8]> {
-        let width = self.width();
-        self.data
-            .chunks_exact_mut(self.width)
-            .map(move |row| &mut row[..width])
-    }
-
     pub fn find(&self, c: u8) -> Option<(usize, usize)> {
-        let pos = self.data.iter().position(|&d| d == c)?;
+        let pos = self.data.as_ref().iter().position(|&d| d == c)?;
 
         Some((pos % self.width, pos / self.width))
     }
 }
 
-impl Index<usize> for OwnedGrid {
+impl<T: AsMut<[u8]> + AsRef<[u8]>> Grid<T> {
+    pub fn rows_mut(&mut self) -> impl Iterator<Item = &mut [u8]> {
+        let width = self.width();
+        self.data
+            .as_mut()
+            .chunks_exact_mut(self.width)
+            .map(move |row| &mut row[..width])
+    }
+}
+
+impl<T: AsRef<[u8]>> Index<usize> for Grid<T> {
     type Output = [u8];
 
     fn index(&self, y: usize) -> &Self::Output {
         let offset = y * self.width;
-        &self.data[offset..(offset + self.width())]
+        &self.data.as_ref()[offset..(offset + self.width())]
     }
 }
 
-impl IndexMut<usize> for OwnedGrid {
+impl<T: AsRef<[u8]>> Display for Grid<T> {
-    fn index_mut(&mut self, y: usize) -> &mut Self::Output {
-        let offset = y * self.width;
-        let width = self.width;
-        &mut self.data[offset..(offset + width)]
-    }
-}
-
-impl Display for OwnedGrid {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{}", String::from_utf8_lossy(&self.data))
+        write!(f, "{}", String::from_utf8_lossy(self.data.as_ref()))
-    }
-}
-
-impl PartialEq<OwnedGrid> for OwnedGrid {
-    fn eq(&self, other: &OwnedGrid) -> bool {
-        // No need to compare width as width is a function of data
-        self.data == other.data
     }
 }
 
 // Custom Clone impl so we don't allocate in `clone_from`
-impl Clone for OwnedGrid {
+impl<T: AsRef<[u8]> + Clone> Clone for Grid<T> {
     fn clone(&self) -> Self {
         Self {
-            width: self.width.clone(),
+            width: self.width,
             data: self.data.clone(),
         }
     }
@@ -395,3 +328,11 @@ impl Clone for OwnedGrid {
         self.data.clone_from(&source.data);
     }
 }
+
+impl<T: AsMut<[u8]> + AsRef<[u8]>> IndexMut<usize> for Grid<T> {
+    fn index_mut(&mut self, y: usize) -> &mut Self::Output {
+        let offset = y * self.width;
+        let width = self.width;
+        &mut self.data.as_mut()[offset..(offset + width)]
+    }
+}

2023/src/day03.rs

@@ -2,7 +2,7 @@ use std::collections::HashMap;
 
 use crate::common::Grid;
 
-fn is_surrounded(grid: &Grid<'_>, y: usize, start: usize, last: usize) -> bool {
+fn is_surrounded(grid: &Grid<&[u8]>, y: usize, start: usize, last: usize) -> bool {
     fn is_symbol(c: u8) -> bool {
         !matches!(c, b'0'..=b'9' | b'.' | b'\n')
     }
@@ -53,7 +53,7 @@ pub fn part1(input: &[u8]) -> anyhow::Result<String> {
     Ok(sum.to_string())
 }
 
-fn find_gear(grid: &Grid<'_>, y: usize, start: usize, end: usize) -> Option<(usize, usize)> {
+fn find_gear(grid: &Grid<&[u8]>, y: usize, start: usize, end: usize) -> Option<(usize, usize)> {
     let x_min = start.saturating_sub(1);
     let x_max = Ord::min(grid.width(), end + 2);
 

2023/src/day10.rs

@@ -22,7 +22,7 @@ fn get_connections(c: u8) -> u8 {
     }
 }
 
-fn find_cycle(map: &Grid<'_>) -> anyhow::Result<(usize, bool, IndexSet)> {
+fn find_cycle(map: &Grid<&[u8]>) -> anyhow::Result<(usize, bool, IndexSet)> {
     let (start_x, start_y) = map.find(b'S').context("Couldn't find starting point")?;
     let mut visited = IndexSet::with_capacity(map.width() * map.height());
     let mut todo = VecDeque::new();

2023/src/day13.rs

@@ -15,7 +15,7 @@ impl Symmetry {
     }
 }
 
-fn find_symmetry(grid: Grid<'_>, differences: usize) -> Option<Symmetry> {
+fn find_symmetry(grid: Grid<&[u8]>, differences: usize) -> Option<Symmetry> {
     // Attempt to find a vertical line of reflection first
     for c in 1..grid.width() {
         if grid
@@ -48,7 +48,7 @@ fn find_symmetry(grid: Grid<'_>, differences: usize) -> Option<Symmetry> {
     None
 }
 
-fn parse_grids(input: &[u8]) -> anyhow::Result<Vec<Grid<'_>>> {
+fn parse_grids(input: &[u8]) -> anyhow::Result<Vec<Grid<&[u8]>>> {
     let mut result = Vec::new();
     let mut start = 0;
     let mut last_newline = 0;

2023/src/day14.rs

@@ -1,5 +1,4 @@
 use crate::common::Grid;
-use crate::common::OwnedGrid;
 
 pub fn part1(input: &[u8]) -> anyhow::Result<String> {
     let grid = Grid::new(input)?;
@@ -23,7 +22,7 @@ pub fn part1(input: &[u8]) -> anyhow::Result<String> {
     Ok(load.to_string())
 }
 
-fn advance(grid: &mut OwnedGrid, stack_heights: &mut [usize]) {
+fn advance(grid: &mut Grid<Vec<u8>>, stack_heights: &mut [usize]) {
     // Tilt north
     stack_heights.fill(0);
     for y in 0..grid.height() {
@@ -100,7 +99,7 @@ fn advance(grid: &mut OwnedGrid, stack_heights: &mut [usize]) {
 
 fn find_cycle(
     it: impl Iterator<Item = usize>,
-    hare: &mut OwnedGrid,
+    hare: &mut Grid<Vec<u8>>,
     stack_heights: &mut [usize],
 ) -> Option<usize> {
     let mut tortoise = hare.clone();
@@ -113,7 +112,7 @@ fn find_cycle(
             return Some(cycle - last_sync);
         } else if cycle.count_ones() == 1 {
             // New power of two, sync up the tortoise and the hare
-            tortoise.clone_from(&hare);
+            tortoise.clone_from(hare);
             last_sync = cycle;
         }
     }
@@ -122,7 +121,7 @@ fn find_cycle(
 
 pub fn part2(input: &[u8]) -> anyhow::Result<String> {
     const GOAL: usize = 1000000000;
-    let mut hare = OwnedGrid::new(input.to_owned())?;
+    let mut hare = Grid::new(input.to_owned())?;
     let mut stack_heights = vec![0; hare.width()];
 
     let mut it = 1..=GOAL;