♻️ refactor: extract `State::eval` for testing bugs the REPL finds

Cargo.lock

@@ -12,3 +12,61 @@ dependencies = [
 [[package]]
 name = "lunar_wave_vm"
 version = "0.1.0"
+dependencies = [
+ "thiserror",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.67"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d433d9f1a3e8c1263d9456598b16fec66f4acc9a74dacffd35c7bb09b3a1328"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5267fca4496028628a95160fc423a33e8b2e6af8a5302579e322e4b520293cae"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.37"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7303ef2c05cd654186cb250d29049a24840ca25d2747c25c0381c8d9e2f582e8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "thiserror"
+version = "1.0.49"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1177e8c6d7ede7afde3585fd2513e611227efd6481bd78d2e82ba1ce16557ed4"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.49"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "10712f02019e9288794769fba95cd6847df9874d49d871d062172f9dd41bc4cc"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"

lunar_wave_vm/Cargo.toml

@@ -4,3 +4,6 @@ description = "A Lua virtual machine implementation"
 version = "0.1.0"
 edition = "2021"
 authors = ["ReactorScram"]
+
+[dependencies]
+thiserror = "1.0.49"

lunar_wave_vm/src/error.rs

@@ -0,0 +1,7 @@
+#[derive (Debug, thiserror::Error)]
+pub enum Error {
+	#[error ("loader")]
+	Loader (#[from] crate::loader::Error),
+	#[error ("VM step")]
+	VmStep (#[from] crate::state::StepError),
+}

lunar_wave_vm/src/lib.rs

@@ -1,8 +1,10 @@
+mod error;
 mod instruction;
 mod loader;
 mod state;
 mod value;
 
+pub use error::Error as Error;
 pub use loader::compile_bytecode_from_file as compile_bytecode_from_file;
 pub use loader::compile_bytecode as compile_bytecode;
 pub use loader::ensure_bytecode as ensure_bytecode;

lunar_wave_vm/src/loader.rs

@@ -29,12 +29,18 @@ pub fn compile_bytecode_from_file (path: &str) -> Vec <u8> {
 	output.stdout.as_slice ().to_vec ()
 }
 
+#[derive (Debug, thiserror::Error)]
+pub enum Error {
+	#[error ("compile")]
+	Compile (String)
+}
+
 /// Invoke `luac` as a subprocess
 /// Luckily luac is single-pass, so we can just pipe in and out
 /// 
 /// `source` is a Vec because we move it to a worker thread
 
-pub fn compile_bytecode (source: Vec <u8>) -> Result <Vec <u8>, String> {
+pub fn compile_bytecode (source: Vec <u8>) -> Result <Vec <u8>, Error> {
 	use std::{
 		io::Write,
 		process::{
@@ -67,7 +73,7 @@ pub fn compile_bytecode (source: Vec <u8>) -> Result <Vec <u8>, String> {
 		Ok (output.stdout)
 	}
 	else {
-		Err (String::from_utf8 (output.stderr).unwrap ())
+		Err (Error::Compile (String::from_utf8 (output.stderr).unwrap ()))
 	}
 }
 
@@ -75,7 +81,7 @@ pub fn compile_bytecode (source: Vec <u8>) -> Result <Vec <u8>, String> {
 /// Lua source code. If it's source code, compiles and returns bytecode.
 /// If it's bytecode, just returns the input.
 
-pub fn ensure_bytecode (buffer: Vec <u8>) -> Result <Vec <u8>, String> {
+pub fn ensure_bytecode (buffer: Vec <u8>) -> Result <Vec <u8>, Error> {
 	let bytecode_header = &[0x1b, 0x4c, 0x75, 0x61, 0x54, 0x00, 0x19, 0x93];
 	if buffer.starts_with (bytecode_header) {
 		return Ok (buffer);

lunar_wave_vm/src/state.rs

@@ -133,11 +133,14 @@ pub enum StepOutput {
 	ChunkReturned (Vec <Value>),
 }
 
-#[derive (Debug)]
-pub struct StepError {
-	frame: StackFrame,
-	inst:  Instruction,
-	msg: &'static str,
+#[derive (Debug, thiserror::Error)]
+pub enum StepError {
+	#[error ("generic")]
+	Generic {
+		frame: StackFrame,
+		inst:  Instruction,
+		msg: &'static str,
+	},
 }
 
 impl State {
@@ -217,7 +220,7 @@ impl State {
 	
 	fn make_step_error (&self, msg: &'static str, inst: &Instruction) -> StepError
 	{
-		StepError {
+		StepError::Generic {
 			frame: self.stack.last ().unwrap ().clone (),
 			inst: inst.clone (),
 			msg,
@@ -900,6 +903,15 @@ impl State {
 		Ok (None)
 	}
 	
+	pub fn eval (&mut self, src: &str) -> Result <Vec <Value>, crate::Error>
+	{
+		let bytecode = crate::compile_bytecode (src.as_bytes ().to_vec ())?;
+		let chunk = crate::parse_chunk (&bytecode).unwrap ();
+		
+		self.set_chunk (chunk);
+		Ok (self.execute ()?)
+	}
+	
 	pub fn execute (&mut self) 
 	-> Result <Vec <Value>, StepError> {
 		let max_iters = 2000;

lunar_wave_vm/src/tests.rs

@@ -206,29 +206,9 @@ fn function_calls () {
 	
 	let mut vm = crate::State::new (crate::Chunk::default (), upvalues);
 	
-	{
-		let bc = crate::compile_bytecode (b"print (x ())".to_vec ()).unwrap ();
-		let chunk = crate::parse_chunk (&bc).unwrap ();
-		
-		vm.set_chunk (chunk);
-		vm.execute ().unwrap ();
-	}
-	
-	{
-		let bc = crate::compile_bytecode (b"x = function () return 5 end".to_vec ()).unwrap ();
-		let chunk = crate::parse_chunk (&bc).unwrap ();
-		
-		vm.set_chunk (chunk);
-		vm.execute ().unwrap ();
-	}
-	
-	{
-		let bc = crate::compile_bytecode (b"print (x ())".to_vec ()).unwrap ();
-		let chunk = crate::parse_chunk (&bc).unwrap ();
-		
-		vm.set_chunk (chunk);
-		vm.execute ().unwrap ();
-	}
+	vm.eval ("print (x ())").ok ();
+	vm.eval ("x = function () return 5 end").ok ();
+	vm.eval ("print (x ())").ok ();
 }
 
 #[test]