♻️ refactor: extract a single step method for State

src/main.rs

@@ -57,14 +57,16 @@ fn main () {
 		dbg! (&chunk);
 	}
 	
-	let mut vm = State::default ();
+	let upvalues = State::upvalues_from_args ([exe_name].into_iter ().chain (args));
+	
+	let mut vm = State::new (&chunk, &upvalues);
 	if std::env::var("LUA_DEBUG").is_ok() {
 		vm.debug_print = true;
 	}
 	
-	let upvalues = State::upvalues_from_args ([exe_name].into_iter ().chain (args));
+	
 	
 	vm.breakpoints = breakpoints;
 	
-	vm.execute_chunk (&chunk, &upvalues);
+	vm.execute_chunk ();
 }

src/state.rs

@@ -47,7 +47,7 @@ pub struct Breakpoint {
 }
 
 #[derive (Debug)]
-pub struct State {
+pub struct State <'a> {
 	registers: Vec <Value>,
 	// Currently only used for native function calls
 	top: usize,
@@ -56,25 +56,8 @@ pub struct State {
 	pub debug_print: bool,
 	pub breakpoints: Vec <Breakpoint>,
 	step_count: u32,
-}
-
-impl Default for State {
-	fn default () -> Self {
-		Self {
-			registers: vec! [Value::Nil; 16],
-			top: 0,
-			stack: vec! [
-				StackFrame {
-					program_counter: 0,
-					block_idx: 0,
-					register_offset: 0,
-				},
-			],
-			debug_print: false,
-			breakpoints: Default::default(),
-			step_count: 0,
-		}
-	}
+	chunk: &'a Chunk,
+	upvalues: &'a [Value],
 }
 
 fn lw_print (l: &mut State) -> i32 {
@@ -93,7 +76,30 @@ fn lw_print (l: &mut State) -> i32 {
 	1
 }
 
-impl State {
+pub enum StepOutput {
+	ChunkReturned (Vec <Value>),
+}
+
+impl <'a> State <'a> {
+	pub fn new (chunk: &'a Chunk, upvalues: &'a [Value]) -> Self {
+		Self {
+			registers: vec! [Value::Nil; 16],
+			top: 0,
+			stack: vec! [
+				StackFrame {
+					program_counter: 0,
+					block_idx: 0,
+					register_offset: 0,
+				},
+			],
+			debug_print: false,
+			breakpoints: Default::default(),
+			step_count: 0,
+			chunk,
+			upvalues,
+		}
+	}
+	
 	pub fn upvalues_from_args <I: Iterator <Item = String>> (args: I) -> Vec <Value>
 	{
 		let arg = args.map (|s| Value::from (s)).enumerate ();
@@ -131,11 +137,8 @@ impl State {
 		self.top - self.stack.last ().unwrap ().register_offset
 	}
 	
-	pub fn execute_chunk (&mut self, chunk: &Chunk, upvalues: &[Value]) 
-	-> Vec <Value> {
-		let max_iters = 2000;
-		
-		for _ in 0..max_iters {
+	pub fn step (&mut self) -> Option <StepOutput> {
+		let chunk = self.chunk;
 		self.step_count += 1;
 		
 		let frame = self.stack.last_mut ().unwrap ().clone ();
@@ -217,7 +220,7 @@ impl State {
 						}
 						
 						// Skip the PC increment at the bottom of the loop
-							continue;
+						return None;
 					},
 					Value::RsFunc (x) => {
 						let current_frame = self.stack.last ().unwrap ();
@@ -260,7 +263,7 @@ impl State {
 					}
 					else {
 						// TODO: This isn't really correct
-							upvalues [usize::from (uv.idx)].clone ()
+						self.upvalues [usize::from (uv.idx)].clone ()
 					};
 					new_upvalues.push (val);
 				}
@@ -346,7 +349,7 @@ impl State {
 				
 				let frame = self.stack.last ().unwrap ();
 				let value = if frame.register_offset == 0 {
-						upvalues.get (b).unwrap ().clone ()
+					self.upvalues.get (b).unwrap ().clone ()
 				}
 				else if let Some (cell) = self.registers [frame.register_offset - 1].as_closure () 
 				{
@@ -355,7 +358,7 @@ impl State {
 					value.clone ()
 				}
 				else {
-						upvalues.get (b).unwrap ().clone ()
+					self.upvalues.get (b).unwrap ().clone ()
 				};
 				
 				let table = value.as_table ().expect ("GetTabUp only works on tables").borrow ();
@@ -520,7 +523,7 @@ impl State {
 				}
 				else {
 					// Return from the entire program
-						return self.registers [a..(a + b - 1)].to_vec();
+					return Some (StepOutput::ChunkReturned (self.registers [a..(a + b - 1)].to_vec()));
 				}
 			},
 			Instruction::Return0 => {
@@ -628,7 +631,7 @@ impl State {
 				frame.block_idx = closure.idx;
 				
 				// Skip the PC increment
-					continue;
+				return None;
 			},
 			Instruction::Test (a, _k) => {
 				if self.reg (*a).is_truthy() {
@@ -643,6 +646,19 @@ impl State {
 			let frame = self.stack.last_mut ().unwrap ();
 			frame.program_counter = next_pc;
 		}
+		
+		None
+	}
+	
+	pub fn execute_chunk (&mut self) 
+	-> Vec <Value> {
+		let max_iters = 2000;
+		
+		for _ in 0..max_iters {
+			match self.step () {
+				None => (),
+				Some (StepOutput::ChunkReturned (x)) => return x,
+			}
 		}
 		
 		dbg! (self);

src/tests.rs

@@ -23,9 +23,9 @@ fn calculate_hash<T: Hash>(t: &T) -> u64 {
 /// and returns the output
 
 fn run_chunk (args: &[&str], chunk: &Chunk) -> Vec <Value> {
-	let mut vm = State::default ();
 	let upvalues = State::upvalues_from_args (args.into_iter ().map (|s| s.to_string ()));
-	vm.execute_chunk (chunk, &upvalues)
+	let mut vm = State::new (chunk, &upvalues);
+	vm.execute_chunk ()
 }
 
 /// Takes arguments and Lua bytecode, loads it, runs it,
@@ -118,10 +118,9 @@ fn bools () {
 	] {
 		let expected: Vec <Value> = expected;
 		
-		let mut vm = State::default ();
 		let upvalues = State::upvalues_from_args (arg.into_iter ().map (|s| s.to_string ()));
-		
-		let actual = vm.execute_chunk (&chunk, &upvalues);
+		let mut vm = State::new (&chunk, &upvalues);
+		let actual = vm.execute_chunk ();
 		assert_eq! (actual, expected);
 	}
 }
@@ -175,9 +174,9 @@ fn floats () {
 		(vec! ["_exe_name", " "], vec! [3.5.into ()]),
 	] {
 		let expected: Vec <Value> = expected;
-		let mut vm = State::default ();
 		let upvalues = State::upvalues_from_args (arg.into_iter ().map (|s| s.to_string ()));
-		let actual = vm.execute_chunk (&chunk, &upvalues);
+		let mut vm = State::new (&chunk, &upvalues);
+		let actual = vm.execute_chunk ();
 		
 		assert_eq! (actual, expected);
 	}
@@ -197,9 +196,9 @@ fn fma () {
 		(vec! ["_exe_name"], vec! [122.into ()]),
 	] {
 		let expected: Vec <Value> = expected;
-		let mut vm = State::default ();
 		let upvalues = State::upvalues_from_args (arg.into_iter ().map (|s| s.to_string ()));
-		let actual = vm.execute_chunk (&chunk, &upvalues);
+		let mut vm = State::new (&chunk, &upvalues);
+		let actual = vm.execute_chunk ();
 		
 		assert_eq! (actual, expected);
 	}