add a vm and stack for execution.

add some basic opt tests

src/debug.rs

@@ -1,6 +1,17 @@
-use mox::value::Value;
-use mox::{Chunk, ConversionError, OptCode};
+use crate::value::Value;
+use crate::{Chunk, ConversionError, OptCode};
+use std::env;
 
+pub fn trace_enabled() -> bool {
+    match env::var("DEBUG_TRACE_EXECUTION") {
+        Ok(value) => match value.to_lowercase().as_str() {
+            "true" | "1" | "yes" | "on" => true,
+            "false" | "0" | "no" | "off" => false,
+            _ => false,
+        },
+        Err(_e) => false,
+    }
+}
 pub fn disassemble_chunk(chunk: &Chunk, name: &str) {
     // println!("{:?}", chunk);
     println!("== {} ==", name);
@@ -9,8 +20,13 @@ pub fn disassemble_chunk(chunk: &Chunk, name: &str) {
         offset = disassemble_instruction(&chunk, offset);
     }
 }
-fn disassemble_instruction(chunk: &Chunk, offset: usize) -> usize {
+pub fn disassemble_instruction(chunk: &Chunk, offset: usize) -> usize {
     print!("{:04} ", offset);
+    if offset > 0 && chunk.lines[offset] == chunk.lines[offset - 1] {
+        print!("   | ");
+    } else {
+        print!("{:>4} ", chunk.lines[offset]);
+    }
     let instruction: Result<OptCode, ConversionError> = chunk.code[offset].try_into();
     match instruction {
         Ok(code) => match code {
@@ -20,9 +36,15 @@ fn disassemble_instruction(chunk: &Chunk, offset: usize) -> usize {
             OptCode::OpReturn => {
                 return simple_instruction("OpReturn", offset);
             }
+            OptCode::OpNegate => {
+                return simple_instruction(&format!("{:}", code), offset);
+            }
+            OptCode::OpAdd | OptCode::OpSubstract | OptCode::OpMultiply | OptCode::OpDivide => {
+                return simple_instruction(&format!("{:}", code), offset);
+            }
         },
         Err(e) => {
-            println!("Unknown optcode {:?}", e);
+            println!("{:}: '{:}'", e.message, e.invalid_value);
             return offset + 1;
         }
     }
@@ -39,6 +61,6 @@ fn constant_instruction(name: &str, chunk: &Chunk, offset: usize) -> usize {
     println!();
     return offset + 2;
 }
-fn print_value(value: Value) {
-    print!("{:}", value);
+pub fn print_value(value: Value) {
+    print!("'{:}'", value);
 }

src/lib.rs

@@ -1,4 +1,9 @@
+pub mod debug;
 pub mod value;
+pub mod vm;
+
+use std::fmt;
+use std::u16;
 
 use value::Value;
 
@@ -6,11 +11,17 @@ use value::Value;
 pub enum OptCode {
     OpReturn,
     OpConstant,
+    OpNegate,
+    OpAdd,
+    OpSubstract,
+    OpMultiply,
+    OpDivide,
 }
 #[derive(Debug)]
 pub struct Chunk {
     pub code: Vec<u8>,
     pub constants: Vec<Value>,
+    pub lines: Vec<u16>,
 }
 
 impl From<OptCode> for u8 {
@@ -18,11 +29,45 @@ impl From<OptCode> for u8 {
         match code {
             OptCode::OpReturn => 0,
             OptCode::OpConstant => 1,
+            OptCode::OpNegate => 2,
+            OptCode::OpAdd => 3,
+            OptCode::OpSubstract => 4,
+            OptCode::OpMultiply => 5,
+            OptCode::OpDivide => 6,
         }
     }
 }
+impl fmt::Display for OptCode {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "{}",
+            match self {
+                OptCode::OpConstant => "OpConstant",
+                OptCode::OpNegate => "OpNegate",
+                OptCode::OpReturn => "OpReturn",
+                OptCode::OpAdd => "OpAdd",
+                OptCode::OpSubstract => "OpSubtract",
+                OptCode::OpMultiply => "OpMultiply",
+                OptCode::OpDivide => "OpDivide",
+            }
+        )
+    }
+}
 #[derive(Debug)]
-pub struct ConversionError;
+pub struct ConversionError {
+    invalid_value: u8,
+    message: String,
+}
+
+impl ConversionError {
+    fn new(invalid_value: u8) -> Self {
+        ConversionError {
+            invalid_value,
+            message: format!("Invalid opcode"),
+        }
+    }
+}
 
 impl TryFrom<u8> for OptCode {
     type Error = ConversionError;
@@ -30,7 +75,12 @@ impl TryFrom<u8> for OptCode {
         match code {
             0 => Ok(OptCode::OpReturn),
             1 => Ok(OptCode::OpConstant),
-            _ => Err(ConversionError),
+            2 => Ok(OptCode::OpNegate),
+            3 => Ok(OptCode::OpAdd),
+            4 => Ok(OptCode::OpSubstract),
+            5 => Ok(OptCode::OpMultiply),
+            6 => Ok(OptCode::OpDivide),
+            _ => Err(ConversionError::new(code)),
         }
     }
 }
@@ -40,10 +90,12 @@ impl Chunk {
         Self {
             code: vec![],
             constants: vec![],
+            lines: vec![],
         }
     }
-    pub fn write(&mut self, byte: u8) {
+    pub fn write(&mut self, byte: u8, line: u16) {
         self.code.push(byte);
+        self.lines.push(line);
     }
     pub fn write_value(&mut self, add: Value) -> u8 {
         self.constants.push(add);
@@ -67,8 +119,8 @@ mod tests {
         let mut chunk = Chunk::new();
         let constant_idx: u8 = chunk.write_value(1.2);
         assert_eq!(constant_idx, 0);
-        chunk.write(OptCode::OpConstant.into());
-        chunk.write(constant_idx);
+        chunk.write(OptCode::OpConstant.into(), 123);
+        chunk.write(constant_idx, 123);
         let pred: OptCode = chunk.code[0].try_into().unwrap();
         assert_eq!(pred, OptCode::OpConstant);
     }
@@ -76,7 +128,7 @@ mod tests {
     fn try_into_constant() {
         let mut chunk = Chunk::new();
         let constant_idx: u8 = chunk.write_value(1.2);
-        chunk.write(OptCode::OpConstant.into());
-        chunk.write(constant_idx);
+        chunk.write(OptCode::OpConstant.into(), 123);
+        chunk.write(constant_idx, 123);
     }
 }

src/main.rs

@@ -1,15 +1,22 @@
+use mox::vm::{InterpretResult, VM};
 use mox::Chunk;
 use mox::OptCode;
-mod debug;
-
-use debug::disassemble_chunk;
 
 fn main() {
     let mut chunk = Chunk::new();
-    let constant_idx: u8 = chunk.write_value(1.2);
-    chunk.write(OptCode::OpConstant.into());
-    chunk.write(constant_idx);
-    chunk.write(OptCode::OpReturn.into());
 
-    disassemble_chunk(&chunk, "test chunk");
+    let constant_idx: u8 = chunk.write_value(1.2);
+    chunk.write(OptCode::OpConstant.into(), 123);
+    chunk.write(constant_idx, 123);
+
+    let constant_idx: u8 = chunk.write_value(5.2);
+    chunk.write(OptCode::OpConstant.into(), 125);
+    chunk.write(constant_idx, 125);
+
+    chunk.write(OptCode::OpAdd.into(), 124);
+
+    chunk.write(OptCode::OpReturn.into(), 126);
+
+    let mut vm: VM = VM::new();
+    let _: InterpretResult = vm.interpret(&chunk);
 }

src/vm.rs

@@ -0,0 +1,174 @@
+use crate::debug::{disassemble_instruction, print_value, trace_enabled};
+use crate::Value;
+use crate::{Chunk, ConversionError, OptCode};
+
+pub struct VM<'a> {
+    chunk: Option<&'a Chunk>,
+    ip: usize,
+    stack: Vec<Value>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum InterpretResult {
+    InterpretOk,
+    InterpretCompileError,
+    InterpretRuntimeError,
+}
+
+impl<'a> VM<'a> {
+    pub fn new() -> Self {
+        VM {
+            chunk: None,
+            ip: 0,
+            stack: vec![],
+        }
+    }
+    pub fn interpret(&mut self, chunk: &'a Chunk) -> InterpretResult {
+        self.chunk = Some(chunk);
+        self.ip = 0;
+        self.run()
+    }
+
+    fn read_byte(&mut self) -> u8 {
+        match self.chunk {
+            Some(chunk) => {
+                let result = chunk.code[self.ip];
+                self.ip += 1;
+                return result;
+            }
+            None => {
+                panic!("could not read byte")
+            }
+        }
+    }
+    fn read_constant(&mut self) -> f64 {
+        match self.chunk {
+            Some(chunk) => chunk.constants[self.read_byte() as usize],
+            None => {
+                panic!("could not read constant")
+            }
+        }
+    }
+    fn run(&mut self) -> InterpretResult {
+        while let Some(chunk) = self.chunk {
+            if self.ip >= chunk.code.len() {
+                break;
+            }
+            if trace_enabled() {
+                print!("          ");
+                println!("{:?}", self.stack);
+                disassemble_instruction(&chunk, self.ip);
+            }
+            let byte: Result<OptCode, ConversionError> = self.read_byte().try_into();
+
+            match byte {
+                Ok(instruction) => match instruction {
+                    OptCode::OpReturn => match self.stack.pop() {
+                        Some(v) => {
+                            print_value(v);
+                            println!();
+                            return InterpretResult::InterpretOk;
+                        }
+                        None => {
+                            return InterpretResult::InterpretOk;
+                        }
+                    },
+                    OptCode::OpConstant => {
+                        let constant: Value = self.read_constant();
+                        self.stack.push(constant);
+                    }
+                    OptCode::OpNegate => match self.stack.pop() {
+                        Some(v) => {
+                            self.stack.push(-v);
+                        }
+                        None => {
+                            return InterpretResult::InterpretRuntimeError;
+                        }
+                    },
+                    OptCode::OpAdd => match (self.stack.pop(), self.stack.pop()) {
+                        (Some(b), Some(a)) => {
+                            self.stack.push(a + b);
+                        }
+                        (_, _) => {
+                            return InterpretResult::InterpretRuntimeError;
+                        }
+                    },
+                    OptCode::OpSubstract => match (self.stack.pop(), self.stack.pop()) {
+                        (Some(b), Some(a)) => {
+                            self.stack.push(a - b);
+                        }
+                        (_, _) => {
+                            return InterpretResult::InterpretRuntimeError;
+                        }
+                    },
+                    OptCode::OpMultiply => match (self.stack.pop(), self.stack.pop()) {
+                        (Some(b), Some(a)) => {
+                            self.stack.push(a * b);
+                        }
+                        (_, _) => {
+                            return InterpretResult::InterpretRuntimeError;
+                        }
+                    },
+                    OptCode::OpDivide => match (self.stack.pop(), self.stack.pop()) {
+                        (Some(b), Some(a)) => {
+                            self.stack.push(a / b);
+                        }
+                        (_, _) => {
+                            return InterpretResult::InterpretRuntimeError;
+                        }
+                    },
+                },
+                Err(_e) => {
+                    return InterpretResult::InterpretRuntimeError;
+                }
+            }
+        }
+        return InterpretResult::InterpretRuntimeError;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn unary_opts() {
+        let mut chunk = Chunk::new();
+
+        let constant_idx: u8 = chunk.write_value(1.2);
+        chunk.write(OptCode::OpConstant.into(), 123);
+        chunk.write(constant_idx, 123);
+        chunk.write(OptCode::OpNegate.into(), 124);
+        chunk.write(OptCode::OpReturn.into(), 125);
+
+        let mut vm: VM = VM::new();
+        let result: InterpretResult = vm.interpret(&chunk);
+        assert_eq!(result, InterpretResult::InterpretOk);
+    }
+    #[test]
+    fn binary_opts() {
+        let mut chunk = Chunk::new();
+
+        let constant_idx: u8 = chunk.write_value(1.2);
+        chunk.write(OptCode::OpConstant.into(), 123);
+        chunk.write(constant_idx, 123);
+
+        let constant_idx: u8 = chunk.write_value(5.2);
+        chunk.write(OptCode::OpConstant.into(), 125);
+        chunk.write(constant_idx, 125);
+
+        chunk.write(OptCode::OpAdd.into(), 126);
+
+        let constant_idx: u8 = chunk.write_value(3.0);
+        chunk.write(OptCode::OpConstant.into(), 127);
+        chunk.write(constant_idx, 127);
+
+        chunk.write(OptCode::OpDivide.into(), 128);
+
+        chunk.write(OptCode::OpReturn.into(), 126);
+
+        let mut vm: VM = VM::new();
+        let result: InterpretResult = vm.interpret(&chunk);
+        assert_eq!(result, InterpretResult::InterpretOk);
+    }
+}