chore: add neighbours + matrix to map helpers for Pt

clechasseur · clechasseur · commit 79d681f5bb2d · 2025-02-01T16:34:02.000-05:00
diff --git a/aoclp/src/positioning/pt.rs b/aoclp/src/positioning/pt.rs
@@ -1,10 +1,17 @@
-use std::fmt::{Display, Formatter};
+use std::collections::HashMap;
+use std::fmt::{Debug, Display, Formatter};
+use std::hash::Hash;
 use std::ops::{Add, AddAssign, Sub, SubAssign};
 use std::str::FromStr;
 use std::sync::OnceLock;
 
+use strum::IntoEnumIterator;
+
 use crate::captures::CapturesHelper;
 use crate::num::{zero, Signed, Zero};
+use crate::positioning::direction::eight_points::Direction8;
+use crate::positioning::direction::four_points::Direction4;
+use crate::positioning::direction::MovementDirection;
 use crate::regex::Regex;
 
 /// A point in 2D space.
@@ -20,6 +27,26 @@ impl<T> Pt<T> {
     }
 }
 
+impl<T> Pt<T>
+where
+    Self: Add<Output = Self> + Copy,
+    Direction4: MovementDirection<T>,
+{
+    pub fn four_neighbours(self) -> impl Iterator<Item = Self> {
+        Direction4::iter().map(move |dir| self + dir.displacement())
+    }
+}
+
+impl<T> Pt<T>
+where
+    Self: Add<Output = Self> + Copy,
+    Direction8: MovementDirection<T>,
+{
+    pub fn eight_neighbours(self) -> impl Iterator<Item = Self> {
+        Direction8::iter().map(move |dir| self + dir.displacement())
+    }
+}
+
 impl<T, U, V> From<(U, V)> for Pt<T>
 where
     U: Into<T>,
@@ -135,3 +162,24 @@ where
 {
     (a.x - b.x).abs() + (a.y - b.y).abs()
 }
+
+/// Given a two-dimensional matrix of elements, returns a map of
+/// [`Pt`] associated with the element at that position in the matrix.
+pub fn matrix_to_map<M, R, T, PT>(matrix: M) -> HashMap<Pt<PT>, T>
+where
+    M: IntoIterator<Item = R>,
+    R: IntoIterator<Item = T>,
+    PT: TryFrom<usize>,
+    <PT as TryFrom<usize>>::Error: Debug,
+    Pt<PT>: Hash + Eq,
+{
+    matrix
+        .into_iter()
+        .enumerate()
+        .flat_map(|(y, row)| {
+            row.into_iter()
+                .enumerate()
+                .map(move |(x, t)| (Pt::new(x.try_into().unwrap(), y.try_into().unwrap()), t))
+        })
+        .collect()
+}
diff --git a/aoclp_solutions/src/y2024/day_04.rs b/aoclp_solutions/src/y2024/day_04.rs
@@ -2,7 +2,7 @@ use std::collections::HashMap;
 use std::iter::successors;
 
 use aoclp::positioning::direction::eight_points::Direction8;
-use aoclp::positioning::pt::Pt;
+use aoclp::positioning::pt::{matrix_to_map, Pt};
 use aoclp::solvers_impl::input::safe_get_input_as_terrain;
 use strum::IntoEnumIterator;
 
@@ -69,17 +69,7 @@ impl WordSearch {
 
 impl From<Vec<Vec<char>>> for WordSearch {
     fn from(value: Vec<Vec<char>>) -> Self {
-        Self(
-            value
-                .into_iter()
-                .enumerate()
-                .flat_map(|(y, row)| {
-                    row.into_iter()
-                        .enumerate()
-                        .map(move |(x, c)| (Pt::new(x as i64, y as i64), c))
-                })
-                .collect(),
-        )
+        Self(matrix_to_map(value))
     }
 }
 
