simplify number parsing

src/day_05/parsing.rs

@@ -1,33 +1,19 @@
 use super::model::{Line, Point};
-use crate::parsing::{newline, parse_number};
+use crate::parsing::{newline, parse_n, parse_number};
-use yap::{IntoTokens, Tokens};
+use yap::Tokens;
 
 pub fn parse_point(tokens: &mut impl Tokens<Item = char>) -> Option<Point> {
-    let numbers: Vec<usize> = tokens
+    parse_n(tokens, &|t| parse_number(t), &|t| t.token(',')).map(|point: [usize; 2]| Point {
-        .sep_by(|t| parse_number(t), |t| t.token(','))
+        x: point[0],
-        .collect();
+        y: point[1],
-    if numbers.len() == 2 {
+    })
-        Some(Point {
-            x: numbers[0],
-            y: numbers[1],
-        })
-    } else {
-        None
-    }
 }
 
 pub fn parse_line(tokens: &mut impl Tokens<Item = char>) -> Option<Line> {
-    let points: Vec<Point> = tokens
+    parse_n(tokens, &|t| parse_point(t), &|t| t.token(',')).map(|points: [Point; 2]| Line {
-        .sep_by(|t| parse_point(t), |t| t.tokens(" -> ".into_tokens()))
+        start: points[0],
-        .collect();
+        end: points[1],
-    if points.len() == 2 {
+    })
-        Some(Line {
-            start: points[0],
-            end: points[1],
-        })
-    } else {
-        None
-    }
 }
 
 pub fn parse_lines(tokens: &mut impl Tokens<Item = char>) -> Vec<Line> {

src/parsing.rs

@@ -30,11 +30,9 @@ pub fn parse_number_with_radix<T: Num>(
             c.is_digit(base) && remaining >= 0
         })
         .collect();
-    if !digits.is_empty() {
+    (!digits.is_empty())
-        T::from_str_radix(&digits, base).ok()
+        .then(|| T::from_str_radix(&digits, base).ok())
-    } else {
+        .flatten()
-        None
-    }
 }
 
 pub fn parse_n<T: Debug, P: Tokens<Item = char>, const N: usize>(