♻️ refactor
_
parent
b07de4810d
commit
8c70469276
213
src/main.rs
213
src/main.rs
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@ -1,3 +1,5 @@
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use std::collections::BTreeMap;
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enum Instruction {
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VarArgPrep (i32),
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GetTabUp (u8, u8, u8),
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@ -21,7 +23,8 @@ enum Value {
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// These are all bogus, I haven't figured out how to implement
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// tables and function pointers yet
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BogusArg,
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BogusArg (Vec <String>),
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BogusEnv (BTreeMap <String, Value>),
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BogusPrint,
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}
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@ -48,6 +51,115 @@ struct Chunk {
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constants: Vec <Value>,
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}
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struct VirtualMachine {
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registers: Vec <Value>,
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// i32 makes it a little easier to implement jumps
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program_counter: i32,
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}
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impl Default for VirtualMachine {
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fn default () -> Self {
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Self {
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registers: vec! [Value::Nil; 256],
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program_counter: 0,
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}
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}
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}
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impl VirtualMachine {
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fn execute_chunk (&mut self, chunk: &Chunk, upvalues: &Vec <Value>) {
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let max_iters = 2000;
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for _ in 0..max_iters {
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let instruction = chunk.instructions.get (usize::try_from (self.program_counter).unwrap ()).unwrap ();
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let r = &mut self.registers;
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let k = &chunk.constants;
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match instruction {
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Instruction::Call (a, b, c) => {
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// Take arguments from registers [a + 1, a + b)
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// Call the function in register [a]
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// Return values in registers [a, a + c - 1)
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//
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// That is, call a with b - 1 arguments and expect c returns
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//
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// e.g. CALL 0 2 1 mean "Call 0 with 1 argument, return 1 value", like for printing a constant
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// TODO: Only implement printing constants for now
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let a = usize::try_from (*a).unwrap ();
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assert_eq! (*b, 2);
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assert_eq! (*c, 1);
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println! ("{:?}", r [a + 1]);
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},
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Instruction::EqK (a, b, c_k) => {
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let a = usize::try_from (*a).unwrap ();
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let b = usize::try_from (*b).unwrap ();
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let equal = r [a] == k [b];
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match (equal, c_k) {
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(true, 0) => self.program_counter += 1,
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(false, 1) => self.program_counter += 1,
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_ => (),
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}
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},
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Instruction::GetTabUp (a, b, c) => {
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let a = usize::try_from (*a).unwrap ();
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let b = usize::try_from (*b).unwrap ();
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let c = usize::try_from (*c).unwrap ();
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let env = match upvalues.get (b).unwrap () {
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Value::BogusEnv (x) => x,
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_ => panic! ("Only allowed upvalue is BogusEnv"),
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};
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let key = match k.get (c).unwrap () {
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Value::String (s) => s,
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_ => panic! ("GetTabUp only supports string keys"),
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};
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let value = env.get (key).unwrap ();
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r [a] = value.clone ();
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},
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Instruction::GetI (a, b, c) => {
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let a = usize::try_from (*a).unwrap ();
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let b = usize::try_from (*b).unwrap ();
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let c = usize::try_from (*c).unwrap ();
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let table = r.get (b).unwrap ();
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let value = match table {
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Value::BogusArg (arg) => arg.get (c).unwrap ().as_str().into (),
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_ => unimplemented!(),
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};
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r [a] = value;
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},
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Instruction::Jmp (sJ) => self.program_counter += sJ,
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Instruction::LoadK (a, bx) => {
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let a = usize::try_from (*a).unwrap ();
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let bx = usize::try_from (*bx).unwrap ();
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r [a] = k [bx].clone ();
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},
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Instruction::Return (_a, _b, _c) => {
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break;
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},
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Instruction::VarArgPrep (_) => (),
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_ => (),
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}
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self.program_counter += 1;
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}
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}
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}
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fn main() {
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let arg: Vec <_> = std::env::args ().collect ();
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@ -76,96 +188,15 @@ fn main() {
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].into_iter ().map (|s| Value::from (s)).collect (),
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};
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let mut registers = vec! [Value::default (); 256];
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let env = BTreeMap::from_iter ([
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("arg", Value::BogusArg (arg.clone ())),
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("print", Value::BogusPrint),
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].map (|(k, v)| (k.to_string (), v)).into_iter ());
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let upvalues = vec! [
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Value::BogusEnv (env),
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];
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let mut program_counter = 0i32;
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let max_iters = 2000;
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for _ in 0..max_iters {
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let instruction = chunk.instructions.get (usize::try_from (program_counter).unwrap ()).unwrap ();
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let r = &mut registers;
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let k = &chunk.constants;
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match instruction {
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Instruction::Call (a, b, c) => {
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// Take arguments from registers [a + 1, a + b)
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// Call the function in register [a]
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// Return values in registers [a, a + c - 1)
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//
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// That is, call a with b - 1 arguments and expect c returns
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//
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// e.g. CALL 0 2 1 mean "Call 0 with 1 argument, return 1 value", like for printing a constant
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// TODO: Only implement printing constants for now
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let a = usize::try_from (*a).unwrap ();
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assert_eq! (*b, 2);
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assert_eq! (*c, 1);
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println! ("{:?}", r [a + 1]);
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},
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Instruction::EqK (a, b, c_k) => {
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let a = usize::try_from (*a).unwrap ();
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let b = usize::try_from (*b).unwrap ();
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let equal = r [a] == k [b];
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match (equal, c_k) {
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(true, 0) => program_counter += 1,
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(false, 1) => program_counter += 1,
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_ => (),
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}
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},
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Instruction::GetTabUp (a, b, c) => {
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let a = usize::try_from (*a).unwrap ();
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let b = usize::try_from (*b).unwrap ();
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let c = usize::try_from (*c).unwrap ();
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// Only supported upvalue is `_ENV`
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assert_eq! (b, 0);
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let key = k.get (c).unwrap ();
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let value = match key {
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Value::String (s) => match s.as_str() {
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"arg" => Value::BogusArg,
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"print" => Value::BogusPrint,
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_ => panic! ("key not in _ENV upvalue"),
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},
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_ => unimplemented!(),
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};
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r [a] = value;
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},
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Instruction::GetI (a, b, c) => {
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let a = usize::try_from (*a).unwrap ();
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let b = usize::try_from (*b).unwrap ();
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let c = usize::try_from (*c).unwrap ();
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let table = r.get (b).unwrap ();
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let value = match table {
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Value::BogusArg => arg.get (c).unwrap ().as_str().into (),
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_ => unimplemented!(),
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};
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r [a] = value;
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},
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Instruction::Jmp (sJ) => program_counter += sJ,
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Instruction::LoadK (a, bx) => {
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let a = usize::try_from (*a).unwrap ();
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let bx = usize::try_from (*bx).unwrap ();
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r [a] = k [bx].clone ();
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},
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Instruction::Return (_a, _b, _c) => {
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break;
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},
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Instruction::VarArgPrep (_) => (),
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_ => (),
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}
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program_counter += 1;
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}
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let mut vm = VirtualMachine::default ();
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vm.execute_chunk (&chunk, &upvalues);
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}
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