✅ test: fix up some bugs to support an embedding example

Cargo.toml

@@ -1,4 +1,5 @@
 [workspace]
+resolver = "2"
 members = [
 	"lunar_wave_cli",
 	"lunar_wave_vm",

examples/embedding.rs

@@ -1,5 +0,0 @@
-fn main () -> Result <(), ()> {
-	println! ("Embedding");
-	
-	Ok (())
-}

lunar_wave_cli/Cargo.toml

@@ -3,7 +3,7 @@ name = "lunar_wave_cli"
 description = "A Lua CLI implementation"
 version = "0.1.0"
 edition = "2021"
-author = "ReactorScram"
+authors = ["ReactorScram"]
 
 [dependencies]
 lunar_wave_vm = { path = "../lunar_wave_vm" }

lunar_wave_vm/Cargo.toml

@@ -3,4 +3,4 @@ name = "lunar_wave_vm"
 description = "A Lua virtual machine implementation"
 version = "0.1.0"
 edition = "2021"
-author = "ReactorScram"
+authors = ["ReactorScram"]

lunar_wave_vm/src/lib.rs

@@ -4,11 +4,13 @@ mod state;
 mod value;
 
 pub use loader::compile_bytecode_from_file as compile_bytecode_from_file;
+pub use loader::compile_bytecode_from_stdin as compile_bytecode_from_stdin;
 pub use loader::parse_chunk as parse_chunk;
 pub use state::Breakpoint as Breakpoint;
 pub use state::State as State;
 pub use state::StepError as StepError;
 pub use state::StepOutput as StepOutput;
+pub use value::Value as Value;
 
 #[cfg (test)]
 mod tests;

lunar_wave_vm/src/loader.rs

@@ -36,7 +36,7 @@ pub fn compile_bytecode_from_file (path: &str) -> Vec <u8> {
 /// 
 /// `source` is a Vec because we move it to a worker thread
 
-pub (crate) fn compile_bytecode_from_stdin (source: Vec <u8>) -> Vec <u8> {
+pub fn compile_bytecode_from_stdin (source: Vec <u8>) -> Vec <u8> {
 	use std::{
 		io::Write,
 		process::{

lunar_wave_vm/src/state.rs

@@ -206,12 +206,12 @@ impl <'a> State <'a> {
 	
 	/// Short form to get access to a register within our window
 	
-	fn reg (&self, i: u8) -> &Value {
+	pub fn reg (&self, i: u8) -> &Value {
 		let frame = self.stack.last ().unwrap ();
 		&self.registers [frame.register_offset + i as usize]
 	}
 	
-	fn reg_mut (&mut self, i: u8) -> &mut Value {
+	pub fn reg_mut (&mut self, i: u8) -> &mut Value {
 		let frame = self.stack.last ().unwrap ();
 		&mut self.registers [frame.register_offset + i as usize]
 	}
@@ -330,22 +330,24 @@ impl <'a> State <'a> {
 					Value::RsFunc (x) => {
 						let current_frame = self.stack.last ().unwrap ();
 						let new_offset = current_frame.register_offset + usize::from (*a) + 1;
+						
+						// Trash the stack frame so it doesn't point to a
+						// valid Lua function
 						self.stack.push (StackFrame {
 							program_counter: 65535, // Bogus for native functions
 							block_idx: 65535, // Bogus
 							register_offset: new_offset,
 						});
 						
-						// No clue what the '1' is doing here
-						let b = if b == 0 {
+						let num_args = if b == 0 {
 							self.top - *a as usize
 						}
 						else {
-							b
+							b - 1
 						};
 						
 						// Call
-						let num_results = x (self, b - 1);
+						let num_results = x (self, num_args);
 						
 						let popped_frame = self.stack.pop ().unwrap ();
 						let offset = popped_frame.register_offset - 1;
@@ -678,7 +680,7 @@ impl <'a> State <'a> {
 					self.top = popped_frame.register_offset - 1 + b - 1;
 				}
 				else {
-					// Return from the entire program
+					// Return from the entire chunk
 					return Ok (Some (StepOutput::ChunkReturned (self.registers [a..(a + b - 1)].to_vec())));
 				}
 			},
@@ -778,26 +780,30 @@ impl <'a> State <'a> {
 				
 				*self.reg_mut (*a) = x;
 			},
-			Instruction::TailCall (a, b, _c, k) => {
+			Instruction::TailCall (a, b, c, k) => {
+				let a = usize::from (*a);
 				assert! (!k, "closing over values in tail calls not implemented");
 				
-				// Shift closure and inputs into place
-				let a = usize::from (*a);
-				let b = usize::from (*b);
-				let offset = frame.register_offset - 1;
-				for i in (offset)..(offset + b) {
-					self.registers [i] = self.registers [i + a + 1].take ();
-				}
+				let offset = frame.register_offset;
+				let value = self.registers [offset + a].take ();
+				match value {
+					Value::BogusClosure (closure) => {
+						let closure = closure.borrow ();
 						
-				let value = &self.registers [offset];
-				let closure = if let Some (x) = value.as_closure () {
-					x
+						// Shift inputs into place
+						
+						let b = usize::from (*b);
+						
+						let num_args = if b == 0 {
+							self.top - a
 						}
 						else {
-					dbg! (self);
-					panic! ("OP_TAILCALL only implemented for closures");
+							b - 1
 						};
-				let closure = closure.borrow ();
+						
+						for i in (offset)..(offset + num_args) {
+							self.registers [i] = self.registers [i + a + 1].take ();
+						}
 						
 						// Jump into the other function
 						
@@ -808,6 +814,50 @@ impl <'a> State <'a> {
 						// Skip the PC increment
 						return Ok (None);
 					},
+					Value::RsFunc (x) => {
+						// Shift inputs into place
+						let b = usize::from (*b);
+						for i in (offset)..(offset + b) {
+							self.registers [i] = self.registers [i + a + 1].take ();
+						}
+						
+						let frame = self.stack.last_mut ().unwrap ();
+						// Trash the stack frame so it doesn't point
+						// to any valid Lua function
+						*frame = StackFrame {
+							block_idx: 65535,
+							program_counter: 65535,
+							register_offset: offset,
+						};
+						
+						let num_args = if b == 0 {
+							self.top - a
+						}
+						else {
+							b - 1
+						};
+						
+						// Call
+						let num_results = x (self, num_args);
+						let popped_frame = self.stack.pop ().unwrap ();
+						
+						if self.stack.is_empty () {
+							// The whole chunk is exiting
+							return Ok (Some (StepOutput::ChunkReturned (self.registers [a..(a + num_results)].to_vec())));
+						}
+						else {
+							// Set up top for the next call
+							if *c == 0 {
+								self.top = popped_frame.register_offset - 1 + num_results;
+							}
+						}
+					},
+					_ => {
+						dbg! (&self.stack);
+						panic! ("OP_TAILCALL argument must be a function");
+					},
+				}
+			},
 			Instruction::Test (a, k) => {
 				if self.reg (*a).is_truthy() != *k {
 					next_pc += 1;

lunar_wave_vm/src/tests.rs

@@ -359,6 +359,25 @@ fn tables_2 () {
 	run_source (&[], src);
 }
 
+#[test]
+fn tailcall () {
+	use crate::instruction::Instruction;
+	
+	let src = r#"
+	return tonumber ("5")
+	"#;
+	
+	let bc = loader::compile_bytecode_from_stdin (src.as_bytes ().to_vec ());
+	let chunk = loader::parse_chunk_from_bytes (&bc).unwrap ();
+	
+	assert_eq! (chunk.blocks [0].instructions [3], Instruction::TailCall (0, 2, 1, false));
+	
+	let actual = run_chunk (&[], &chunk);
+	let expected = vec! [Value::from (5)];
+	
+	assert_eq! (actual, expected);
+}
+
 #[test]
 fn value_size () {
 	// Per https://www.lua.org/doc/jucs05.pdf,

lunar_wave_vm/tests/embedding.rs

@@ -0,0 +1,42 @@
+use lunar_wave_vm as lwvm;
+
+#[test]
+fn embedding () {
+	use lwvm::{
+		State,
+		Value,
+	};
+	
+	let src = br#"
+	return host_lib.add (14, 12)
+	"#;
+	
+	fn host_add (l: &mut State, num_args: usize) -> usize {
+		assert_eq! (num_args, 2);
+		let a = l.reg (0).as_int ().unwrap ();
+		let b = l.reg (1).as_int ().unwrap ();
+		*l.reg_mut (0) = Value::from (a + b + 1993);
+		1
+	}
+	
+	let bytecode = lwvm::compile_bytecode_from_stdin (src.to_vec ());
+	let mut rdr = std::io::Cursor::new (bytecode);
+	let chunk = lwvm::parse_chunk (&mut rdr).unwrap ();
+	
+	let host_lib = [
+		("add", Value::RsFunc (host_add)),
+	].into_iter ().map (|(k, v)| (k.to_string (), v));
+	
+	let env = [
+		("host_lib", Value::from_iter (host_lib.into_iter ())),
+	].into_iter ().map (|(k, v)| (k.to_string (), v));
+	
+	let upvalues = vec! [
+		Value::from_iter (env.into_iter ()),
+	];
+	
+	let mut vm = State::new (&chunk, &upvalues);
+	let output = vm.execute_chunk (&vec! []).unwrap ();
+	
+	assert_eq! (output, vec! [Value::from (2019)]);
+}