std::math::big: add bitwise not operator to the Int structure

std/math/big/int.jule

@@ -256,6 +256,22 @@ impl Int {
         ret self.cmp(y) == 0
     }
 
+    // Bitwise not.
+    pub fn bit_not(self): Int {
+        let mut r = clone(self)
+        if r.neg {
+            sub_one(r.nat.bits)
+            r.nat.fit()
+        } else {
+            let carry = add_one(r.nat.bits)
+            if carry == 0b1 {
+                r.nat.bits = append(r.nat.bits, 0b1)
+            }
+        }
+        r.neg = !r.neg
+        ret r
+    }
+
     // Reports whether number is odd.
     pub fn odd(self): bool {
         ret self.nat.odd()

std/math/big/int_test.jule

@@ -65,6 +65,13 @@ static cases_int_mod = [
     ["1010", "+", "10000000000", "-", "1111110110", "-"],
 ]
 
+static cases_int_bit_not: [][]i64 = [
+    [-20, 19],
+    [-90, 89],
+    [20, -21],
+    [90, -91],
+]
+
 fn test_common_int_op(mut &t: &T, op: str, &cases: [][]str) {
     for _, c in cases {
         let mut n1 = Int.from_bits(c[0], c[1] == "-") else {
@@ -130,6 +137,17 @@ fn test_int_mod(mut t: &T) {
     test_common_int_op(t, "%", cases_int_mod)
 }
 
+#test
+fn test_int_bit_not(mut t: &T) {
+    for _, c in cases_int_bit_not {
+        let i = Int.new(c[0])
+        let r = ^i
+        if (r.to_i64()!) != c[1] {
+            t.errorf("^{} != {}", c[0], c[1])
+        }
+    }
+}
+
 #test
 fn test_int_lt(mut t: &T) {
     t.assert(!Int.from_bits("1011010", false)!.lt(Int.from_bits("00001011010", false)!), "1) 1011010 < 00001011010")