avoid parsing if string is empty

src/bng/score.rs

@@ -33,7 +33,7 @@ pub use de::*;
 
 use super::Expression as Instruction;
 
-#[derive(Deref, From)]
+#[derive(Deref, From, Default)]
 #[cfg_attr(debug_assertions, derive(Serialize, Debug))]
 pub struct Atoms(Vec<Atom>);
 

src/bng/score/de.rs

@@ -2,7 +2,7 @@ use derive_new::new;
 use nom::{
     character::complete::one_of,
     combinator::all_consuming,
-    multi::many0,
+    multi::{many0, many1},
     sequence::{preceded, terminated},
     Parser,
 };
@@ -108,7 +108,11 @@ impl<'de> Deserialize<'de> for Atoms {
         const FIELDS: &[&str] = &["notes", "sheet"];
         let NotesSheet { notes, sheet } =
             deserializer.deserialize_struct("NotesSheet", FIELDS, NotesSheetVisitor)?;
-        flat_atom_parser_mapper::<D, _>(&sheet, flat_atom_parser(&notes))
+        if sheet.is_empty() {
+            Ok(Default::default())
+        } else {
+            flat_atom_parser_mapper::<D, _>(&sheet, flat_atom_parser(&notes))
+        }
     }
 }
 
@@ -128,7 +132,7 @@ where
     P: Parser<&'a str, FlatAtom, nom::error::Error<&'a str>>,
 {
     all_consuming(terminated(
-        many0(preceded(maybe_yml_str_space(), parser)),
+        many1(preceded(maybe_yml_str_space(), parser)),
         maybe_yml_str_space(),
     ))(input)
     .map_err(nom_err_message)