Update parser.rs

Author: RabbitAlbatross

macros/src/parser.rs

@@ -49,3 +49,16 @@ impl Parse for FieldDef {
         Ok(FieldDef { name, size })
     }
 }
+
+pub fn parse_bit_width(ty: &syn::Ident) -> Result<u8> {
+    let ty_str = ty.to_string();
+    if !ty_str.starts_with("u") {
+        return Err(syn::Error::new_spanned(ty, format!("Invalid type {ty_str}, expected u{{1..128}}")));
+    }
+    let size = ty_str[1..].parse::<u8>()
+        .map_err(|e| syn::Error::new_spanned(ty, format!("Could not parse type size: {e}")))?;
+    if size == 0 || size > 128 {
+        return Err(syn::Error::new_spanned(ty, format!("Invalid size for {ty_str}, expected u{{1..128}}")));
+    }
+    Ok(size)
+}