From 5de9f1c89968b2550501c20d44f40cd6d5ddafcc Mon Sep 17 00:00:00 2001
From: Haibib Kerim <haibib@puffer5.stanford.edu>
Date: Wed, 22 Apr 2026 15:34:40 -0700
Subject: [PATCH] added test-evaluator

---
 fix/evaluator/Cargo.toml           |   9 +++
 fix/evaluator/src/lib.rs           |   5 ++
 fix/evaluator/src/mockruntime.rs   |  17 +++++
 fix/evaluator/src/testevaluator.rs | 108 +++++++++++++++++++++++++++++
 4 files changed, 139 insertions(+)
 create mode 100644 fix/evaluator/Cargo.toml
 create mode 100644 fix/evaluator/src/lib.rs
 create mode 100644 fix/evaluator/src/mockruntime.rs
 create mode 100644 fix/evaluator/src/testevaluator.rs

diff --git a/fix/evaluator/Cargo.toml b/fix/evaluator/Cargo.toml
new file mode 100644
index 0000000..2fa90b7
--- /dev/null
+++ b/fix/evaluator/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "test-evaluator"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
\ No newline at end of file
diff --git a/fix/evaluator/src/lib.rs b/fix/evaluator/src/lib.rs
new file mode 100644
index 0000000..639338c
--- /dev/null
+++ b/fix/evaluator/src/lib.rs
@@ -0,0 +1,5 @@
+#![no_std]
+#![allow(dead_code)]
+
+pub mod mockruntime;
+pub mod testevaluator;
diff --git a/fix/evaluator/src/mockruntime.rs b/fix/evaluator/src/mockruntime.rs
new file mode 100644
index 0000000..2d45878
--- /dev/null
+++ b/fix/evaluator/src/mockruntime.rs
@@ -0,0 +1,17 @@
+use core::clone::Clone;
+use core::result::Result;
+
+pub trait MockRuntime {
+    type BlobData: Clone + core::fmt::Debug;
+    type TreeData: Clone + core::fmt::Debug;
+    type Handle: Clone + core::fmt::Debug;
+    type Error;
+
+    fn create_blob(&mut self, data: Self::BlobData) -> Self::Handle;
+    fn create_tree(&mut self, data: Self::TreeData) -> Self::Handle;
+
+    fn get_blob(&self, handle: &Self::Handle) -> Result<Self::BlobData, Self::Error>;
+    fn get_tree(&self, handle: &Self::Handle) -> Result<Self::TreeData, Self::Error>;
+
+    fn apply(&mut self, combination: &Self::Handle) -> Result<Self::Handle, Self::Error>;
+}
diff --git a/fix/evaluator/src/testevaluator.rs b/fix/evaluator/src/testevaluator.rs
new file mode 100644
index 0000000..795a64b
--- /dev/null
+++ b/fix/evaluator/src/testevaluator.rs
@@ -0,0 +1,108 @@
+extern crate alloc;
+use crate::mockruntime::MockRuntime;
+use alloc::{boxed::Box, vec::Vec};
+
+#[derive(Debug)]
+pub enum Error {
+    OOB,
+    TypeMismatch,
+    UnexpectedFunction,
+}
+
+enum Object {
+    Blob(Box<[u8]>),
+    Tree(Box<[usize]>),
+}
+
+pub struct FakeRuntime {
+    store: Vec<Object>,
+}
+
+impl FakeRuntime {
+    fn new() -> Self {
+        Self { store: Vec::new() }
+    }
+
+    fn create_blob_i64(&mut self, data: i64) -> <FakeRuntime as MockRuntime>::Handle {
+        self.create_blob(Box::from(data.to_le_bytes()))
+    }
+}
+
+impl MockRuntime for FakeRuntime {
+    type Handle = usize;
+    type BlobData = Box<[u8]>;
+    type TreeData = Box<[usize]>;
+    type Error = Error;
+
+    fn create_blob(&mut self, data: Self::BlobData) -> Self::Handle {
+        let index = self.store.len();
+        self.store.push(Object::Blob(data));
+        index
+    }
+
+    fn create_tree(&mut self, data: Self::TreeData) -> Self::Handle {
+        let index = self.store.len();
+        self.store.push(Object::Tree(data));
+        index
+    }
+
+    fn get_blob(&self, handle: &Self::Handle) -> Result<Self::BlobData, Self::Error> {
+        match self.store.get(*handle) {
+            Some(Object::Blob(data)) => Ok(data.clone()),
+            Some(Object::Tree(_)) => Err(Error::TypeMismatch),
+            None => Err(Error::OOB),
+        }
+    }
+
+    fn get_tree(&self, handle: &Self::Handle) -> Result<Self::TreeData, Self::Error> {
+        match self.store.get(*handle) {
+            Some(Object::Tree(data)) => Ok(data.clone()),
+            Some(Object::Blob(_)) => Err(Error::TypeMismatch),
+            None => Err(Error::OOB),
+        }
+    }
+
+    fn apply(&mut self, combination: &Self::Handle) -> Result<Self::Handle, Self::Error> {
+        let span = self.get_tree(combination)?;
+        if span.len() < 2 {
+            return Err(Error::OOB);
+        }
+
+        let function = self.get_blob(&span[0])?;
+        if function.as_ref() != b"+" {
+            return Err(Error::UnexpectedFunction);
+        }
+
+        let left_bytes: [u8; 8] = (*self.get_blob(&span[1])?)
+            .try_into()
+            .map_err(|_| Error::OOB)?;
+        let left = i64::from_le_bytes(left_bytes);
+        let right_bytes: [u8; 8] = (*self.get_blob(&span[2])?)
+            .try_into()
+            .map_err(|_| Error::OOB)?;
+        let right = i64::from_le_bytes(right_bytes);
+
+        Ok(self.create_blob_i64(left + right))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_add() {
+        let mut fake_runtime = FakeRuntime::new();
+
+        let one_literal = fake_runtime.create_blob_i64(1);
+        let two_literal = fake_runtime.create_blob_i64(2);
+        let plus_literal = fake_runtime.create_blob(Box::from(*b"+"));
+
+        let tree = fake_runtime.create_tree(Box::from([plus_literal, one_literal, two_literal]));
+        let result = fake_runtime.apply(&tree).expect("valid apply addition");
+
+        assert_eq!(
+            fake_runtime.get_blob(&result).expect("valid result blob"),
+            Box::from(3_i64.to_le_bytes())
+        );
+    }
+}