add helper method for parsing exactly N of something

src/parsing.rs

@@ -1,4 +1,5 @@
 use num::Num;
+use std::fmt::Debug;
 use yap::{IntoTokens, Tokens};
 pub fn space(tokens: &mut impl Tokens<Item = char>) -> bool {
     tokens.token(' ')
@@ -36,6 +37,19 @@ pub fn parse_number_with_radix<T: Num>(
     }
 }
 
+pub fn parse_n<T: Debug, P: Tokens<Item = char>, const N: usize>(
+    tokens: &mut P,
+    parser: &dyn Fn(&mut P) -> Option<T>,
+    separator: &dyn Fn(&mut P) -> bool,
+) -> Option<[T; N]> {
+    let elements: Vec<T> = tokens.sep_by(parser, separator).collect();
+    if elements.len() != 10 {
+        None
+    } else {
+        Some(elements.try_into().unwrap())
+    }
+}
+
 #[cfg(test)]
 mod test {
     use yap::IntoTokens;