From 9811d265f6e1b117bf4f210b75d35f40b986ac5f Mon Sep 17 00:00:00 2001
From: _ <_@_>
Date: Tue, 26 Sep 2023 22:34:47 -0500
Subject: [PATCH] :star: for loops with integer counters counting up only

---
 src/instruction.rs         |  4 ++++
 src/loader.rs              |  2 ++
 src/main.rs                | 19 +++++++++++++++++--
 src/state.rs               | 21 +++++++++++++++++++++
 src/value.rs               |  7 +++++++
 test_vectors/fizz_buzz.lua |  3 +++
 6 files changed, 54 insertions(+), 2 deletions(-)
 create mode 100644 test_vectors/fizz_buzz.lua

diff --git a/src/instruction.rs b/src/instruction.rs
index ed5b22d..6a4502c 100644
--- a/src/instruction.rs
+++ b/src/instruction.rs
@@ -10,6 +10,10 @@ pub enum Instruction {
 	
 	ExtraArg (u32),
 	
+	ForLoop (u8, u32),
+	
+	ForPrep (u8, u32),
+	
 	GetField (u8, u8, u8),
 	
 	// Get Immediate?
diff --git a/src/loader.rs b/src/loader.rs
index d3c09aa..3d53bde 100644
--- a/src/loader.rs
+++ b/src/loader.rs
@@ -88,6 +88,8 @@ pub fn parse_inst (buf: [u8; 4]) -> Option <Inst>
 		0x46 => Inst::Return (a, b, c, k),
 		0x47 => Inst::Return0,
 		0x48 => Inst::Return1 (a),
+		0x49 => Inst::ForLoop (a, bx),
+		0x4a => Inst::ForPrep (a, bx),
 		0x4e => Inst::SetList (a, b, c, k),
 		0x4f => Inst::Closure (a, bx),
 		0x51 => Inst::VarArgPrep (a.into ()),
diff --git a/src/main.rs b/src/main.rs
index b3be927..bcac3d4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,5 @@
+// cargo run -- --script test_vectors/fizz_buzz.lua
+
 mod instruction;
 mod loader;
 mod state;
@@ -9,8 +11,21 @@ mod tests;
 fn main () {
 	use state::State;
 	
+	let mut script = String::from ("test_vectors/hello.lua");
+	
+	let mut args = std::env::args ();
+	let exe_name = args.next ().unwrap ();
+	
+	while let Some (arg) = args.next () {
+		match arg.as_str () {
+			"--script" => script = args.next ().unwrap (),
+			"--" => break,
+			_ => panic! ("can't parse args"),
+		}
+	}
+	
 	let lua_file = {
-		let source = std::fs::read ("test_vectors/hello.lua").expect ("couldn't load Lua source code");
+		let source = std::fs::read (script).expect ("couldn't load Lua source code");
 		let bytecode = loader::compile_bytecode(source);
 		let mut rdr = std::io::Cursor::new (bytecode);
 		loader::parse_chunk (&mut rdr).unwrap ()
@@ -21,7 +36,7 @@ fn main () {
 		vm.debug_print = true;
 	}
 	
-	let upvalues = State::upvalues_from_args (std::env::args ());
+	let upvalues = State::upvalues_from_args ([exe_name].into_iter ().chain (args));
 	
 	vm.breakpoints.push (state::Breakpoint {
 		block_idx: 3,
diff --git a/src/state.rs b/src/state.rs
index 722810b..ad234ac 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -214,6 +214,27 @@ impl State {
 					
 					assert_eq! (*ax, 0, "implemented only for ax == 0");
 				},
+				Instruction::ForLoop (a, bx) => {
+					let mut iter = self.reg (*a + 3).as_int ().unwrap ();
+					iter += 1;
+					*self.reg_mut (*a + 3) = iter.into ();
+					
+					let stop = self.reg (*a + 1).as_int ().unwrap ();
+					
+					if iter <= stop {
+						next_pc -= i32::try_from (*bx).unwrap ();
+					}
+				},
+				Instruction::ForPrep (a, bx) => {
+					let start = self.reg (*a).as_int ().unwrap ();
+					let stop = self.reg (*a + 1).as_int ().unwrap ();
+					
+					if start > stop {
+						next_pc += i32::try_from (*bx).unwrap () + 1;
+					}
+					
+					*self.reg_mut (*a + 3) = start.into ();
+				},
 				Instruction::GetField (a, b, c) => {
 					let t = match self.reg (*b) {
 						Value::Table (t) => t,
diff --git a/src/value.rs b/src/value.rs
index 4547065..ad2b8b7 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -146,6 +146,13 @@ impl Value {
 		}
 	}
 	
+	pub fn as_int (&self) -> Option <i64> {
+		match self {
+			Self::Integer (x) => Some (*x),
+			_ => None,
+		}
+	}
+	
 	pub fn as_table (&self) -> Option <&Rc <RefCell <Table>>> {
 		match self {
 			Self::Table (t) => Some (t),
diff --git a/test_vectors/fizz_buzz.lua b/test_vectors/fizz_buzz.lua
new file mode 100644
index 0000000..2ec0f58
--- /dev/null
+++ b/test_vectors/fizz_buzz.lua
@@ -0,0 +1,3 @@
+for i = 1, 50 do
+	print (i)
+end