Add gen.sh to create Rust stub

native/aoc/gen.sh

@@ -0,0 +1,58 @@
+#!/bin/zsh
+
+FULL_YEAR=$1
+YEAR=${1:(-2)}
+DAY=$(printf '%02d' $2)
+SRC_FILE=./src/year_${FULL_YEAR}/day_${YEAR}_${DAY}.rs
+
+if [[ ! -e $SRC_FILE ]]; then
+    touch "$SRC_FILE"
+    cat << EOF > "$SRC_FILE"
+pub fn solve_${YEAR}_${DAY}(raw_input: String) -> (i32, i32) {
+    let input = process(&raw_input);
+    (part_1(&input), part_2(&input))
+}
+
+fn process(raw_input: &str) -> Vec<&str> {
+    raw_input
+        .trim()
+        .split('\n')
+        .collect()
+}
+
+fn part_1(input: &[&str]) -> i32 {
+    input.len() as i32
+}
+
+fn part_2(input: &[&str]) -> i32 {
+    input.len() as i32
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::util::io_helpers::read_input_from_resources;
+    use super::*;
+
+    const YEAR: i16 = $1;
+    const DAY: i8 = $2;
+
+    #[test]
+    fn test_process() {
+        let given = "hello\nthere";
+        let expected = vec!["hello", "there"];
+
+        assert_eq!(process(given), expected);
+    }
+
+    #[test]
+    fn test_solution() {
+        let given = read_input_from_resources(YEAR, DAY, false);
+        let expected = (3, 3);
+
+        assert_eq!(solve_${YEAR}_${DAY}(given), expected);
+    }
+}
+EOF
+else
+    echo "Source ${SRC_FILE} already exists"
+fi