From 95d4d133d1eb5e0eb44cd928d8183d890e970a13 Mon Sep 17 00:00:00 2001
From: Tom French <15848336+TomAFrench@users.noreply.github.com>
Date: Wed, 8 May 2024 17:27:52 +0100
Subject: [PATCH] feat: add `Not` trait to stdlib (#4999)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->

## Summary\*

This PR adds a `Not` trait which is an equivalent of Rust's
`std::ops::Not` trait which represents a bitwise NOT.

## Additional Context



## Documentation\*

Check one:
- [ ] No documentation needed.
- [x] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [x] I have tested the changes locally.
- [x] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.
---
 docs/docs/noir/standard_library/traits.md |  9 +++++++
 noir_stdlib/src/ops.nr                    |  2 +-
 noir_stdlib/src/ops/bit.nr                | 21 ++++++++++++++++
 noir_stdlib/src/uint128.nr                | 30 +++++++++++++++++++++--
 4 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/docs/docs/noir/standard_library/traits.md b/docs/docs/noir/standard_library/traits.md
index 08370dde9e..96a7b8e2f2 100644
--- a/docs/docs/noir/standard_library/traits.md
+++ b/docs/docs/noir/standard_library/traits.md
@@ -241,6 +241,15 @@ impl Rem for i64 { fn rem(self, other: i64) -> i64 { self % other } }
 Implementations:
 #include_code neg-trait-impls noir_stdlib/src/ops/arith.nr rust
 
+### `std::ops::Not`
+
+#include_code not-trait noir_stdlib/src/ops/bit.nr rust
+
+`Not::not` is equivalent to the unary bitwise NOT operator `!`.
+
+Implementations:
+#include_code not-trait-impls noir_stdlib/src/ops/bit.nr rust
+
 ### `std::ops::{ BitOr, BitAnd, BitXor }`
 
 #include_code bitor-trait noir_stdlib/src/ops/bit.nr rust
diff --git a/noir_stdlib/src/ops.nr b/noir_stdlib/src/ops.nr
index d7ea1dfd48..8b1903cff0 100644
--- a/noir_stdlib/src/ops.nr
+++ b/noir_stdlib/src/ops.nr
@@ -2,4 +2,4 @@ mod arith;
 mod bit;
 
 use arith::{Add, Sub, Mul, Div, Rem, Neg};
-use bit::{BitOr, BitAnd, BitXor, Shl, Shr};
+use bit::{Not, BitOr, BitAnd, BitXor, Shl, Shr};
diff --git a/noir_stdlib/src/ops/bit.nr b/noir_stdlib/src/ops/bit.nr
index ae06520e9c..a31cfee878 100644
--- a/noir_stdlib/src/ops/bit.nr
+++ b/noir_stdlib/src/ops/bit.nr
@@ -1,3 +1,24 @@
+// docs:start:not-trait
+trait Not {
+    fn not(self: Self) -> Self;
+}
+// docs:end:not-trait
+
+// docs:start:not-trait-impls
+impl Not for bool { fn not(self) -> bool { !self } }
+
+impl Not for u64 { fn not(self) -> u64 { !self } }
+impl Not for u32 { fn not(self) -> u32 { !self } }
+impl Not for u16 { fn not(self) -> u16 { !self } }
+impl Not for u8 { fn not(self) -> u8 { !self } }
+impl Not for u1 { fn not(self) -> u1 { !self } }
+
+impl Not for i8 { fn not(self) -> i8 { !self } }
+impl Not for i16 { fn not(self) -> i16 { !self } }
+impl Not for i32 { fn not(self) -> i32 { !self } }
+impl Not for i64 { fn not(self) -> i64 { !self } }
+// docs:end:not-trait-impls
+
 // docs:start:bitor-trait
 trait BitOr {
     fn bitor(self, other: Self) -> Self;
diff --git a/noir_stdlib/src/uint128.nr b/noir_stdlib/src/uint128.nr
index d0f38079e6..9c61fc801f 100644
--- a/noir_stdlib/src/uint128.nr
+++ b/noir_stdlib/src/uint128.nr
@@ -1,4 +1,4 @@
-use crate::ops::{Add, Sub, Mul, Div, Rem, BitOr, BitAnd, BitXor, Shl, Shr};
+use crate::ops::{Add, Sub, Mul, Div, Rem, Not, BitOr, BitAnd, BitXor, Shl, Shr};
 use crate::cmp::{Eq, Ord, Ordering};
 
 global pow64 : Field = 18446744073709551616; //2^64;
@@ -228,11 +228,20 @@ impl Ord for U128 {
     }
 }
 
+impl Not for U128 { 
+    fn not(self) -> U128 {
+        U128 {
+            lo: (!(self.lo as u64)) as Field,
+            hi: (!(self.hi as u64)) as Field
+        }
+    }
+}
+
 impl BitOr for U128 { 
     fn bitor(self, other: U128) -> U128 {
         U128 {
             lo: ((self.lo as u64) | (other.lo as u64)) as Field,
-            hi: ((self.hi as u64) | (other.hi as u64))as Field
+            hi: ((self.hi as u64) | (other.hi as u64)) as Field
         }
     }
 }
@@ -284,3 +293,20 @@ impl Shr for U128 {
         self / U128::from_integer(y)
     } 
 }
+
+mod test {
+    use crate::uint128::{U128, pow64};
+
+    #[test]
+    fn test_not() {
+        let num = U128::from_u64s_le(0, 0);
+        let not_num = num.not();
+
+        let max_u64: Field = pow64 - 1;
+        assert_eq(not_num.hi, max_u64);
+        assert_eq(not_num.lo, max_u64);
+
+        let not_not_num = not_num.not();
+        assert_eq(num, not_not_num);
+    }
+}