represent 4th variant of slots, and disallow empty primary slot names

src/atom/parsers.rs

@@ -210,16 +210,16 @@ impl<'a> Parseable<'a, &'a str> for Slot {
 
     fn parser() -> Self::Parser {
         let wildcard = tag("*").map(|_| Slot::Wildcard);
-        let equals = SlotName::parser()
-            .opt()
+        let equal = tag("=").map(|_| Slot::Equal);
+        let name_equal = SlotName::parser()
             .and(SlotName::parser().preceded_by(tag("/")).opt())
             .followed_by(tag("="))
-            .map(|(primary, sub)| Slot::Equal { primary, sub });
+            .map(|(primary, sub)| Slot::NameEqual { primary, sub });
         let name = SlotName::parser()
             .and(SlotName::parser().preceded_by(tag("/")).opt())
-            .map(|(primary, sub)| Slot::Name { primary, sub });
+            .map(|(primary, sub)| Self::Name { primary, sub });
 
-        wildcard.or(equals).or(name)
+        wildcard.or(equal).or(name_equal).or(name)
     }
 }
 
@@ -585,6 +585,7 @@ mod test {
             "<dev-haskell/wai-3.3:=[]",
             ">=kde-frameworks/kcrash-2.16.0:6*",
             "0-f/merreka+m::k+",
+            "iev-a/h:/n=",
         ];
 
         for atom in atoms {