refactor parse_n to not require borrowing closures

src/day_05/parsing.rs

@@ -3,14 +3,14 @@ use crate::parsing::{newline, parse_n, parse_number};
 use yap::Tokens;
 
 pub fn parse_point(tokens: &mut impl Tokens<Item = char>) -> Option<Point> {
-    parse_n(tokens, &|t| parse_number(t), &|t| t.token(',')).map(|point: [usize; 2]| Point {
+    parse_n(tokens, |t| parse_number(t), |t| t.token(',')).map(|point: [usize; 2]| Point {
         x: point[0],
         y: point[1],
     })
 }
 
 pub fn parse_line(tokens: &mut impl Tokens<Item = char>) -> Option<Line> {
-    parse_n(tokens, &|t| parse_point(t), &|t| t.tokens(" -> ".chars())).map(|points: [Point; 2]| {
+    parse_n(tokens, |t| parse_point(t), |t| t.tokens(" -> ".chars())).map(|points: [Point; 2]| {
         Line {
             start: points[0],
             end: points[1],

src/day_11/parsing.rs

@@ -7,8 +7,8 @@ use super::OctopusGrid;
 pub fn parse_octopus_grid(tokens: &mut impl Tokens<Item = char>) -> Option<OctopusGrid> {
     parse_n(
         tokens,
-        &|t| parse_n(t, &|t| parse_digit(t), &|_| true),
+        |t| parse_n(t, |t| parse_digit(t), |_| true),
-        &|t| newline(t),
+        |t| newline(t),
     )
     .map(|grid| OctopusGrid { grid })
 }

src/day_12/parsing.rs

@@ -10,7 +10,7 @@ pub fn parse_cave_system(tokens: &mut impl Tokens<Item = char>) -> Option<CaveSy
 }
 
 pub fn parse_edge(tokens: &mut impl Tokens<Item = char>) -> Option<[Cave; 2]> {
-    parse_n(tokens, &|t| parse_cave(t), &|t| t.token('-'))
+    parse_n(tokens, |t| parse_cave(t), |t| t.token('-'))
 }
 
 pub fn parse_cave(tokens: &mut impl Tokens<Item = char>) -> Option<Cave> {

src/parsing.rs

@@ -35,14 +35,20 @@ pub fn parse_number_with_radix<T: Num>(
         .flatten()
 }
 
-pub fn parse_n<T: Debug, P: Tokens<Item = char>, const N: usize>(
+pub fn parse_n<R, T, I, P, S, const N: usize>(
-    tokens: &mut P,
+    tokens: &mut T,
-    parser: &dyn Fn(&mut P) -> Option<T>,
+    parser: P,
-    separator: &dyn Fn(&mut P) -> bool,
+    separator: S,
-) -> Option<[T; N]> {
+) -> Option<[R; N]>
+where
+    R: Debug,
+    T: Tokens<Item = I>,
+    P: FnMut(&mut T) -> Option<R>,
+    S: FnMut(&mut T) -> bool,
+{
     tokens
         .sep_by(parser, separator)
-        .collect::<Vec<T>>()
+        .collect::<Vec<R>>()
         .try_into()
         .ok()
 }