Implement is_one for BigUint and BigInt.

Author: Clar Charr

src/bigint.rs

@@ -274,6 +274,11 @@ impl One for BigInt {
     fn one() -> BigInt {
         BigInt::from_biguint(Plus, One::one())
     }
+
+    #[inline]
+    fn is_one(&self) -> bool {
+        self.sign == Plus && self.data.is_one()
+    }
 }
 
 impl Signed for BigInt {

src/biguint.rs

@@ -415,6 +415,11 @@ impl One for BigUint {
     fn one() -> BigUint {
         BigUint::new(vec![1])
     }
+
+    #[inline]
+    fn is_one(&self) -> bool {
+        self.data[..] == [1]
+    }
 }
 
 impl Unsigned for BigUint {}