⭐ allow calling closures

src/main.rs

@@ -4,29 +4,81 @@ mod state;
 mod tests;
 
 fn main() {
-	use state::Instruction as Inst;
-	use state::State;
+	use state::{
+		Block,
+		Chunk,
+		Instruction as Inst,
+		State,
+	};
 	
-	let chunk = state::Chunk {
-		instructions: vec! [
-			Inst::VarArgPrep (0),
-			Inst::LoadK (0, 0),
-			Inst::LoadI (1, 3),
-			Inst::Add (2, 0, 1),
-			Inst::MmBin (0, 1, 6),
-			Inst::GetTabUp (3, 0, 1),
-			Inst::Move (4, 2),
-			Inst::Call (3, 2, 1),
-			Inst::Return (2, 2, 1),
-			Inst::Return (3, 1, 1),
-		],
-		constants: vec! [
-			0.5.into (),
-			"print".into (),
+	/*
+	local function bool_to_x (b)
+		if b then
+			return 99
+		else
+			return 98
+		end
+	end
+
+	local x = bool_to_x (not not arg [1])
+	print (x)
+	return x
+	*/
+	
+	let chunk = Chunk {
+		blocks: vec! [
+			Block {
+				instructions: vec! [
+					Inst::VarArgPrep (0),
+					Inst::Closure (0, 0),
+					Inst::GetTabUp (1, 0, 0),
+					Inst::Move (2, 0),
+					Inst::LoadFalse (3),
+					Inst::Call (2, 2, 0),
+					Inst::Call (1, 0, 1),
+					Inst::GetTabUp (1, 0, 0),
+					Inst::Move (2, 0),
+					Inst::LoadTrue (3),
+					Inst::Call (2, 2, 0),
+					Inst::Call (1, 0, 1),
+					Inst::Move (1, 0),
+					Inst::GetTabUp (2, 0, 1),
+					Inst::GetI (2, 2, 1),
+					Inst::Not (2, 2),
+					Inst::Not (2, 2),
+					Inst::Call (1, 2, 2),
+					Inst::GetTabUp (2, 0, 0),
+					Inst::Move (3, 1),
+					Inst::Call (2, 2, 1),
+					Inst::Return (1, 2, 1),
+					Inst::Return (2, 1, 1),
+				],
+				constants: vec! [
+					"print".into (),
+					"arg".into (),
+				],
+			},
+			Block {
+				instructions: vec! [
+					Inst::Test (0, 0),
+					Inst::Jmp (3),
+					Inst::LoadI (1, 99),
+					Inst::Return1 (1),
+					Inst::Jmp (2),
+					Inst::LoadI (1, 98),
+					Inst::Return1 (1),
+					Inst::Return0,
+				],
+				constants: vec! [],
+			},
 		],
 	};
 	
 	let mut vm = State::default ();
+	if std::env::var("LUA_DEBUG").is_ok() {
+		vm.debug_print = true;
+	}
+	
 	let upvalues = State::upvalues_from_args (std::env::args ());
 	println! ("Returned: {:?}", vm.execute_chunk (&chunk, &upvalues));
 }

src/state.rs

@@ -19,28 +19,40 @@ pub enum Instruction {
 	// Jump
 	Jmp (i32),
 	
+	LoadFalse (u8),
+	
 	// Load Integer?
 	LoadI (u8, i32),
 	
 	// Load Constant
 	LoadK (u8, i32),
 	
+	LoadTrue (u8),
+	
 	// MetaMethod, Binary
 	MmBin (u8, u8, u8),
 	
 	Move (u8, u8),
 	
+	Not (u8, u8),
+	
 	// (A, B, _C) Return B - 1 registers starting with  A
 	Return (u8, u8, u8),
 	
+	Return0,
+	
+	// Return just one register
+	Return1 (u8),
+	
+	Test (u8, i32),
+	
 	VarArgPrep (i32),
 }
 
 #[derive (Clone, Debug, PartialEq)]
 pub enum Value {
 	Nil,
-	False,
-	True,
+	Boolean (bool),
 	Float (f64),
 	String (String),
 	
@@ -48,6 +60,7 @@ pub enum Value {
 	// tables and function pointers yet
 	
 	BogusArg (Vec <String>),
+	BogusClosure (usize),
 	BogusEnv (BTreeMap <String, Value>),
 	BogusPrint,
 }
@@ -89,25 +102,50 @@ impl Value {
 			_ => None,
 		}
 	}
+	
+	fn is_truthy (&self) -> bool {
+		// And this is something Lua does better than JS and Python.
+		
+		match self {
+			Value::Nil => false,
+			Value::Boolean (false) => false,
+			_ => true,
+		}
+	}
 }
 
-pub struct Chunk {
+pub struct Block {
 	pub instructions: Vec <Instruction>,
 	pub constants: Vec <Value>,
 }
 
+pub struct Chunk {
+	pub blocks: Vec <Block>,
+}
+
+#[derive (Debug)]
+struct StackFrame {
+	// i32 makes it a little easier to implement jumps
+	// Starts at 0 right after OP_CALL
+	
+	program_counter: i32,
+	
+	// Starts from 0 for main and 1 for the first closure
+	block_idx: usize,
+	
+	register_offset: usize,
+}
+
 pub struct State {
 	registers: Vec <Value>,
-	
-	// i32 makes it a little easier to implement jumps
-	program_counter: i32,
+	pub debug_print: bool,
 }
 
 impl Default for State {
 	fn default () -> Self {
 		Self {
 			registers: vec! [Value::Nil; 256],
-			program_counter: 0,
+			debug_print: false,
 		}
 	}
 }
@@ -131,11 +169,32 @@ impl State {
 	-> Vec <Value> {
 		let max_iters = 2000;
 		
+		let mut stack = vec! [
+			StackFrame {
+				program_counter: 0,
+				block_idx: 0,
+				register_offset: 0,
+			},
+		];
+		
 		for _ in 0..max_iters {
-			let instruction = chunk.instructions.get (usize::try_from (self.program_counter).unwrap ()).unwrap ();
+			let stack_idx = stack.len () - 1;
+			let frame = stack.get_mut (stack_idx).unwrap ();
+			let block = chunk.blocks.get (frame.block_idx).unwrap ();
 			
-			let r = &mut self.registers;
-			let k = &chunk.constants;
+			let mut next_pc = frame.program_counter;
+			
+			let pc = usize::try_from (frame.program_counter).expect ("program_counter is not a valid usize");
+			let instruction = match block.instructions.get (pc) {
+				Some (x) => x,
+				None => {
+					dbg! (&stack);
+					panic! ("program_counter went out of bounds");
+				}
+			};
+			
+			let r = &mut self.registers [frame.register_offset..];
+			let k = &block.constants;
 			
 			match instruction {
 				Instruction::Add (a, b, c) => {
@@ -160,12 +219,47 @@ impl State {
 					// TODO: Only implement printing values for now
 					
 					let a = usize::try_from (*a).unwrap ();
+					let v_a = r.get (a).unwrap ();
 					
-					assert_eq! (r.get (a).unwrap (), &Value::BogusPrint);
-					assert_eq! (*b, 2);
-					assert_eq! (*c, 1);
+					match v_a {
+						Value::BogusClosure (idx) => {
+							let block_idx = frame.block_idx;
+							let target_block = idx + 1;
+							
+							let current_frame = &stack [stack.len () - 1];
+							
+							stack.push (StackFrame {
+								program_counter: 0,
+								block_idx: target_block,
+								register_offset: current_frame.register_offset + a + 1,
+							});
+							
+							if self.debug_print {
+								println! ("Inst {block_idx}:{pc} calls {target_block}:0");
+								let stack_depth = stack.len ();
+								println! ("stack_depth: {stack_depth}");
+							}
+							
+							// Skip the PC increment at the bottom of the loop
+							continue;
+						},
+						Value::BogusPrint => {
+							// In real Lua, print is a function inside
+							// the runtime. Here it's bogus.
+							
+							// assert_eq! (*b, 2);
+							assert_eq! (*c, 1);
+							
+							println! ("{:?}", r.get (a + 1).unwrap ());
+						},
+						_ => panic! ("Cannot call value {a:?}. backtrace: {stack:?}"),
+					}
+				},
+				Instruction::Closure (a, b) => {
+					let a = usize::try_from (*a).unwrap ();
+					let b = usize::try_from (*b).unwrap ();
 					
-					println! ("{:?}", r.get (a + 1).unwrap ());
+					r [a] = Value::BogusClosure (b);
 				},
 				Instruction::EqK (a, b, c_k) => {
 					let a = usize::try_from (*a).unwrap ();
@@ -174,8 +268,8 @@ impl State {
 					let equal = r [a] == k [b];
 					
 					match (equal, c_k) {
-						(true, 0) => self.program_counter += 1,
-						(false, 1) => self.program_counter += 1,
+						(true, 0) => next_pc += 1,
+						(false, 1) => next_pc += 1,
 						_ => (),
 					}
 				},
@@ -212,7 +306,11 @@ impl State {
 					
 					r [a] = value;
 				},
-				Instruction::Jmp (s_j) => self.program_counter += s_j,
+				Instruction::Jmp (s_j) => next_pc += s_j,
+				Instruction::LoadFalse (a) => {
+					let a  = usize::try_from  (*a).unwrap ();
+					r [a] = Value::Boolean (false);
+				},
 				Instruction::LoadI (a, sbx) => {
 					let a  = usize::try_from  (*a).unwrap ();
 					
@@ -224,6 +322,10 @@ impl State {
 					
 					r [a] = k [bx].clone ();
 				},
+				Instruction::LoadTrue (a) => {
+					let a  = usize::try_from  (*a).unwrap ();
+					r [a] = Value::Boolean (true);
+				},
 				Instruction::MmBin (a, b, _c) => {
 					let a = usize::try_from (*a).unwrap ();
 					let b = usize::try_from (*b).unwrap ();
@@ -244,19 +346,62 @@ impl State {
 					
 					r [a] = r [b].clone ();
 				},
+				Instruction::Not (a, b) => {
+					let a = usize::try_from (*a).unwrap ();
+					let b = usize::try_from (*b).unwrap ();
+					
+					r [a] = Value::Boolean (! r [b].is_truthy());
+				}
 				Instruction::Return (a, b, _c) => {
 					let a = usize::try_from (*a).unwrap ();
 					let b = usize::try_from (*b).unwrap ();
 					
-					return self.registers [a..(a + b - 1)].to_vec();
+					return r [a..(a + b - 1)].to_vec();
+				},
+				Instruction::Return1 (a) => {
+					let a = usize::try_from (*a).unwrap ();
+					let popped_frame = stack.pop ().unwrap ();
+					
+					self.registers [popped_frame.register_offset - 1] = r [a].clone ();
+					
+					let stack_idx = stack.len () - 1;
+					let frame = stack.get (stack_idx).unwrap ();
+					let new_block = frame.block_idx;
+					next_pc = frame.program_counter;
+					
+					if self.debug_print {
+						let old_block = popped_frame.block_idx;
+						let old_pc = popped_frame.program_counter;
+						println! ("Inst {old_block}:{old_pc} returns to inst {new_block}:{next_pc}");
+						let stack_depth = stack.len ();
+						println! ("stack_depth: {stack_depth}");
+					}
+				},
+				Instruction::Test (a, _k) => {
+					let a = usize::try_from (*a).unwrap ();
+					
+					let a = r.get (a).unwrap ();
+					
+					if self.debug_print {
+						println! ("Test {a:?}");
+					}
+					
+					if a.is_truthy() {
+						next_pc += 1;
+					}
 				},
 				Instruction::VarArgPrep (_) => (),
 				x => panic! ("Unimplemented instruction {x:?}"),
 			}
 			
-			self.program_counter += 1;
+			next_pc += 1;
+			{
+				let stack_idx = stack.len () - 1;
+				let frame = stack.get_mut (stack_idx).unwrap ();
+				frame.program_counter = next_pc;
+			}
 		}
 		
-		panic! ("Hit max iterations before chunk returned");
+		panic! ("Hit max iterations before block returned");
 	}
 }

src/tests.rs

@@ -1,10 +1,87 @@
 use crate::state::{
+	Block,
 	Chunk,
 	Instruction as Inst,
 	State,
 	Value,
 };
 
+#[test]
+fn bools () {
+	/*
+	local function bool_to_x (b)
+		if b then
+			return 99
+		else
+			return 98
+		end
+	end
+
+	local x = bool_to_x (not not arg [1])
+	print (x)
+	return x
+	*/
+	
+	let chunk = Chunk {
+		blocks: vec! [
+			Block {
+				instructions: vec! [
+					Inst::VarArgPrep (0),
+					Inst::Closure (0, 0),
+					Inst::Move (1, 0),
+					
+					Inst::LoadFalse (2),
+					Inst::Call (1, 2, 1),
+					
+					Inst::Move (1, 0),
+					Inst::LoadTrue (2),
+					Inst::Call (1, 2, 1),
+					
+					Inst::Move (1, 0),
+					Inst::GetTabUp (2, 0, 0),
+					Inst::GetI (2, 2, 1),
+					Inst::Not (2, 2),
+					Inst::Not (2, 2),
+					Inst::Call (1, 2, 2),
+					Inst::GetTabUp (2, 0, 1),
+					Inst::Move (3, 1),
+					Inst::Call (2, 2, 1),
+					Inst::Return (1, 2, 1),
+					Inst::Return (2, 1, 1),
+				],
+				constants: vec! [
+					"arg".into (),
+					"print".into (),
+				],
+			},
+			Block {
+				instructions: vec! [
+					Inst::Test (0, 0),
+					Inst::Jmp (3),
+					Inst::LoadI (1, 99),
+					Inst::Return1 (1),
+					Inst::Jmp (2),
+					Inst::LoadI (1, 98),
+					Inst::Return1 (1),
+					Inst::Return0,
+				],
+				constants: vec! [],
+			},
+		],
+	};
+	
+	for (arg, expected) in [
+		(vec! ["_exe_name"], vec! [98.into ()]),
+		(vec! ["_exe_name", "asdf"], vec! [99.into ()]),
+	] {
+		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);
+		assert_eq! (actual, expected);
+	}
+}
+
 #[test]
 fn floats () {
 	/*
@@ -17,7 +94,7 @@ fn floats () {
 	return x
 	*/
 	
-	let chunk = Chunk {
+	let block = Block {
 		instructions: vec! [
 			Inst::VarArgPrep (0),
 			Inst::LoadK (0, 0),
@@ -35,6 +112,9 @@ fn floats () {
 			"print".into (),
 		],
 	};
+	let chunk = Chunk {
+		blocks: vec! [block],
+	};
 	
 	for (arg, expected) in [
 		(vec! ["_exe_name"], vec! [3.5.into ()]),
@@ -60,7 +140,7 @@ fn is_93 () {
 	end
 	*/
 	
-	let chunk = Chunk {
+	let block = Block {
 		instructions: vec! [
 			Inst::VarArgPrep (0),
 			Inst::GetTabUp (1, 0, 0),
@@ -88,6 +168,9 @@ fn is_93 () {
 			"it's not 93",
 		].into_iter ().map (Value::from).collect (),
 	};
+	let chunk = Chunk {
+		blocks: vec! [block],
+	};
 	
 	for (arg, expected) in [
 		(vec! ["_exe_name"], vec! [1.into ()]),

test_vectors/bools.lua

@@ -0,0 +1,14 @@
+local function bool_to_x (b)
+	if b then
+		return 99
+	else
+		return 98
+	end
+end
+
+print (bool_to_x (false))
+print (bool_to_x (true))
+
+local x = bool_to_x (not not arg [1])
+print (x)
+return x