feat(tvix/eval): implement boolean inversion operator r/4415

Change-Id: Icb1d449fdee4d67b5f1eefdbc01baa1584ea0a67
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6079
Tested-by: BuildkiteCI
Autosubmit: tazjin <tazjin@tvl.su>
Reviewed-by: grfn <grfn@gws.fyi>

2 files changed, 17 insertions, 1 deletions

diff --git a/tvix/eval/src/value.rs b/tvix/eval/src/value.rs
index cbfff55b49..842d561d67 100644
--- a/tvix/eval/src/value.rs
+++ b/tvix/eval/src/value.rs
@@ -1,6 +1,8 @@
 //! This module implements the backing representation of runtime
 //! values in the Nix language.
 
+use crate::errors::{Error, EvalResult};
+
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum Value {
     Null,
@@ -26,6 +28,16 @@ impl Value {
             Value::Float(_) => "float",
         }
     }
+
+    pub fn as_bool(self) -> EvalResult<bool> {
+        match self {
+            Value::Bool(b) => Ok(b),
+            other => Err(Error::TypeError {
+                expected: "bool",
+                actual: other.type_of(),
+            }),
+        }
+    }
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]
diff --git a/tvix/eval/src/vm.rs b/tvix/eval/src/vm.rs
index 25a9074c75..7b02c68dc1 100644
--- a/tvix/eval/src/vm.rs
+++ b/tvix/eval/src/vm.rs
@@ -81,6 +81,11 @@ impl VM {
                     NumberPair::Integer(i1, i2) => self.push(Value::Integer(i1 / i2)),
                 },
 
+                OpCode::OpInvert => {
+                    let v = self.pop().as_bool()?;
+                    self.push(Value::Bool(!v));
+                }
+
                 OpCode::OpNegate => match self.pop() {
                     Value::Integer(i) => self.push(Value::Integer(-i)),
                     Value::Float(f) => self.push(Value::Float(-f)),
@@ -106,7 +111,6 @@ impl VM {
                     self.push(Value::Bool(eq))
                 }
 
-                OpCode::OpInvert => todo!("invert"),
                 OpCode::OpNull => todo!("null"),
                 OpCode::OpTrue => todo!("true"),
                 OpCode::OpFalse => todo!("false"),