split_from: use generics

src/misc.rs

@@ -1,20 +1,30 @@
-pub fn split_from(min: usize, max: usize, x: usize) -> Vec<Vec<usize>> {
+use std::{iter::Rev, ops::RangeInclusive};
+
+pub fn split_from<T>(min: T, max: T, x: T) -> Vec<Vec<T>>
+where
+    T: std::cmp::PartialOrd
+        + std::ops::Add<usize, Output = T>
+        + std::ops::Sub<usize, Output = T>
+        + Copy
+        + Ord,
+    RangeInclusive<T>: Iterator<Item = T> + DoubleEndedIterator,
+    Rev<RangeInclusive<T>>: Iterator<Item = T>,
+{
     if min > x || x > max {
         return Vec::new();
     }
-    let x_lower = x.checked_sub(1).unwrap_or(min);
+
     let x_upper = (x + 1).min(max);
-    let lower_range = if x_lower != min {
-        (min..=x_lower).rev().collect()
-    } else {
-        Vec::new()
-    };
-    let upper_range = if x_upper != max {
-        (x_upper..=max).collect()
-    } else {
-        Vec::new()
-    };
-    vec![lower_range, upper_range]
+
+    let mut output: Vec<Vec<T>> = Vec::new();
+    if x > min + 1 {
+        let x_lower = x - 1;
+        output.push((min..=x_lower).rev().collect());
+    }
+    if x_upper < max {
+        output.push((x_upper..=max).collect());
+    }
+    output
 }
 
 #[cfg(test)]
@@ -25,8 +35,8 @@ mod test {
     fn split_test() {
         assert_eq!(split_from(0, 6, 2), vec![vec![1, 0], vec![3, 4, 5, 6]]);
 
-        assert_eq!(split_from(0, 6, 0), vec![vec![], vec![1, 2, 3, 4, 5, 6]]);
+        assert_eq!(split_from(0, 6, 0), vec![vec![1, 2, 3, 4, 5, 6]]);
 
-        assert_eq!(split_from(0, 6, 6), vec![vec![5, 4, 3, 2, 1, 0], vec![]]);
+        assert_eq!(split_from(0, 6, 6), vec![vec![5, 4, 3, 2, 1, 0]]);
     }
 }

src/repr.rs

@@ -1,6 +1,5 @@
-use std::fmt;
-
 use crate::misc::split_from;
+use std::fmt;
 
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub enum Piece {