vector2d: Implement ‹Index› and ‹IndexMut› traits

Signed-off-by: Matej Focko <me@mfocko.xyz>

src/bin/day08.rs

@@ -23,11 +23,11 @@ fn count_in(trees: &Input, counted: &mut Visited, swap: bool) {
             pos = pos.swap();
         }
 
-        if *index(trees, &pos) > tallest {
+        if trees[pos] > tallest {
             counted.insert(pos);
         }
 
-        max(tallest, *index(trees, &pos))
+        max(tallest, trees[pos])
     }
 
     (0..trees.len()).for_each(|y| {
@@ -49,14 +49,14 @@ fn count_in_columns(trees: &Input, counted: &mut Visited) {
 }
 
 fn count_visible(trees: &Input, position: SignedPosition, diff: SignedPosition) -> usize {
-    let max_height = *index(trees, &position);
+    let max_height = trees[position];
     let mut visible = 0;
 
     let mut d = 1;
     while in_range(trees, &(position + diff * d)) {
         visible += 1;
 
-        if *index(trees, &(position + diff * d)) >= max_height {
+        if trees[position + diff * d] >= max_height {
             break;
         }
 
@@ -104,7 +104,8 @@ impl Solution<Input, Output> for Day08 {
     fn part_2(input: &Input) -> Output {
         (0..input.len())
             .flat_map(|y| {
-            (0..input[y].len()).map(move |x| compute_scenic_score(input, x as isize, y as isize))
+                (0..input[y].len())
+                    .map(move |x| compute_scenic_score(input, x as isize, y as isize))
             })
             .max()
             .unwrap()

src/bin/day12.rs

@@ -103,7 +103,7 @@ impl Solution<Input, Output> for Day12 {
 
     fn part_1(input: &Input) -> Output {
         fn has_edge(graph: &[Vec<char>], from: &Position, to: &Position) -> bool {
-            get_elevation(*index(graph, to)) - get_elevation(*index(graph, from)) <= 1
+            get_elevation(graph[*to]) - get_elevation(graph[*from]) <= 1
         }
 
         let (start, target) = (find_start(input), find_target(input));
@@ -116,11 +116,11 @@ impl Solution<Input, Output> for Day12 {
 
     fn part_2(input: &Input) -> Output {
         fn has_edge(graph: &[Vec<char>], from: &Position, to: &Position) -> bool {
-            (get_elevation(*index(graph, from)) - get_elevation(*index(graph, to))) <= 1
+            (get_elevation(graph[*from]) - get_elevation(graph[*to])) <= 1
         }
 
         fn is_target(graph: &[Vec<char>], vertex: &Position) -> bool {
-            get_elevation(*index(graph, vertex)) == 0
+            get_elevation(graph[*vertex]) == 0
         }
 
         let start = find_target(input);

src/vector2d.rs

@@ -1,4 +1,5 @@
 use std::cmp::Eq;
+use std::collections::VecDeque;
 use std::fmt::Debug;
 use std::hash::Hash;
 use std::ops::{Add, Index, IndexMut, Mul, Sub};
@@ -23,27 +24,42 @@ impl<T> Vector2D<T> {
     }
 }
 
-pub fn index<'a, C, I>(v: &'a [C], idx: &Vector2D<I>) -> &'a C::Output
-where
-    I: Copy,
+macro_rules! generate_indices {
+    ($container:ty) => {
+        impl<I, C> Index<Vector2D<I>> for $container
+        where
+            I: Copy + TryInto<usize>,
+            <I as TryInto<usize>>::Error: Debug,
             C: Index<usize>,
-    usize: TryFrom<I>,
-    <usize as TryFrom<I>>::Error: Debug,
-{
-    let (x, y): (usize, usize) = (idx.x.try_into().unwrap(), idx.y.try_into().unwrap());
-    &v[y][x]
+        {
+            type Output = C::Output;
+
+            fn index(&self, index: Vector2D<I>) -> &Self::Output {
+                let (x, y): (usize, usize) =
+                    (index.x.try_into().unwrap(), index.y.try_into().unwrap());
+                &self[y][x]
+            }
+        }
+
+        impl<I, C> IndexMut<Vector2D<I>> for $container
+        where
+            I: Copy + TryInto<usize>,
+            <I as TryInto<usize>>::Error: Debug,
+            C: IndexMut<usize>,
+        {
+            fn index_mut(&mut self, index: Vector2D<I>) -> &mut Self::Output {
+                let (x, y): (usize, usize) =
+                    (index.x.try_into().unwrap(), index.y.try_into().unwrap());
+                &mut self[y][x]
+            }
+        }
+    };
 }
 
-pub fn index_mut<'a, C, I>(v: &'a mut [C], idx: &Vector2D<I>) -> &'a mut C::Output
-where
-    I: Copy,
-    C: IndexMut<usize>,
-    usize: TryFrom<I>,
-    <usize as TryFrom<I>>::Error: Debug,
-{
-    let (x, y): (usize, usize) = (idx.x.try_into().unwrap(), idx.y.try_into().unwrap());
-    &mut v[y][x]
-}
+generate_indices!(VecDeque<C>);
+generate_indices!([C]);
+generate_indices!(Vec<C>);
+// generate_indices!([C; N], const N: usize);
 
 pub fn in_range<I, C>(v: &[Vec<C>], idx: &Vector2D<I>) -> bool
 where