impl atom parsing

src/useflag/parsers.rs

@@ -0,0 +1,10 @@
+use mon::{Parser, alpha1, alphanumeric, one_of, take_while};
+
+use crate::useflag::UseFlag;
+
+pub fn useflag<'a>() -> impl Parser<&'a str, Output = UseFlag> {
+    alpha1()
+        .and(alphanumeric().or(take_while(one_of("+_@-".chars()))))
+        .recognize()
+        .map(|output: &str| UseFlag(output.to_string()))
+}