types: don't put parentheses around display of outermost type

So e.g. (1 * 1) -> ((1 + 1) * 1) becomes 1 * 1 -> (1 + 1) * 1

Author: apoelstra

src/types/final_data.rs

@@ -115,10 +115,14 @@ impl fmt::Display for Final {
                     f.write_str("1")?;
                 }
                 (CompleteBound::Sum(..), 0) | (CompleteBound::Product(..), 0) => {
-                    f.write_str("(")?;
+                    if data.index > 0 {
+                        f.write_str("(")?;
+                    }
                 }
                 (CompleteBound::Sum(..), 2) | (CompleteBound::Product(..), 2) => {
-                    f.write_str(")")?;
+                    if data.index > 0 {
+                        f.write_str(")")?;
+                    }
                 }
                 (CompleteBound::Sum(..), _) => f.write_str(" + ")?,
                 (CompleteBound::Product(..), _) => f.write_str(" × ")?,
@@ -216,9 +220,9 @@ mod tests {
         assert_eq!(ty1.to_string(), "2^1024");
 
         let sum = Final::sum(Final::two_two_n(5), Final::two_two_n(10));
-        assert_eq!(sum.to_string(), "(2^32 + 2^1024)");
+        assert_eq!(sum.to_string(), "2^32 + 2^1024");
 
         let prod = Final::product(Final::two_two_n(5), Final::two_two_n(10));
-        assert_eq!(prod.to_string(), "(2^32 × 2^1024)");
+        assert_eq!(prod.to_string(), "2^32 × 2^1024");
     }
 }

src/types/mod.rs

@@ -332,8 +332,16 @@ impl fmt::Display for Bound {
             match (&*data.node, data.n_children_yielded) {
                 (Bound::Free(ref s), _) => f.write_str(s)?,
                 (Bound::Complete(ref comp), _) => fmt::Display::fmt(comp, f)?,
-                (Bound::Sum(..), 0) | (Bound::Product(..), 0) => f.write_str("(")?,
-                (Bound::Sum(..), 2) | (Bound::Product(..), 2) => f.write_str(")")?,
+                (Bound::Sum(..), 0) | (Bound::Product(..), 0) => {
+                    if data.index > 0 {
+                        f.write_str("(")?
+                    }
+                }
+                (Bound::Sum(..), 2) | (Bound::Product(..), 2) => {
+                    if data.index > 0 {
+                        f.write_str(")")?
+                    }
+                }
                 (Bound::Sum(..), _) => f.write_str(" + ")?,
                 (Bound::Product(..), _) => f.write_str(" × ")?,
             }