From a5533ea58b44ae092a6131dea9e1d6fa7fe626d5 Mon Sep 17 00:00:00 2001
From: Alpha Chen <alpha@kejadlen.dev>
Date: Sun, 16 Oct 2022 19:04:46 -0700
Subject: [PATCH] pull lines back out

---
 rust/src/chunk.rs | 25 +++++++++++--------------
 rust/src/main.rs  | 11 ++++++++++-
 rust/src/vm.rs    | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 15 deletions(-)
 create mode 100644 rust/src/vm.rs

diff --git a/rust/src/chunk.rs b/rust/src/chunk.rs
index c57fa76..0fc8169 100644
--- a/rust/src/chunk.rs
+++ b/rust/src/chunk.rs
@@ -8,21 +8,17 @@ pub enum OpCode {
     Return,
 }
 
-#[derive(Debug)]
-pub struct Instruction {
-    op_code: OpCode,
-    line: usize,
-}
-
 #[derive(Debug, Default)]
 pub struct Chunk {
-    pub code: Vec<Instruction>,
+    pub code: Vec<OpCode>,
+    pub lines: Vec<usize>,
     pub constants: Vec<Value>,
 }
 
 impl Chunk {
     pub fn push(&mut self, op_code: OpCode, line: usize) {
-        self.code.push(Instruction { op_code, line });
+        self.code.push(op_code);
+        self.lines.push(line);
     }
 
     pub fn push_constant(&mut self, value: Value, line: usize) {
@@ -39,18 +35,19 @@ impl fmt::Display for Chunk {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let mut last_line: Option<usize> = None;
 
-        for (i, instruction) in self.code.iter().enumerate() {
+        for (i, op_code) in self.code.iter().enumerate() {
             write!(f, "{:04} ", i)?;
-            if last_line == Some(instruction.line) {
+            let line = self.lines[i];
+            if last_line == Some(line) {
                 write!(f, "   | ")?;
             } else {
-                write!(f, "{:>4} ", instruction.line)?;
+                write!(f, "{:>4} ", line)?;
             }
-            last_line = Some(instruction.line);
+            last_line = Some(line);
 
-            match instruction.op_code {
+            match op_code {
                 OpCode::Constant(constant) => {
-                    let value = self.constants[constant];
+                    let value = self.constants[*constant];
                     writeln!(f, "{:<16} {:4} '{}'", "OP_CONSTANT", constant, value)?;
                 }
                 OpCode::Return => writeln!(f, "OP_RETURN")?,
diff --git a/rust/src/main.rs b/rust/src/main.rs
index 71cc773..344475d 100644
--- a/rust/src/main.rs
+++ b/rust/src/main.rs
@@ -1,13 +1,22 @@
 use chunk::{Chunk, OpCode};
+use vm::VM;
+
+use anyhow::Result;
 
 mod chunk;
 mod value;
+mod vm;
 
-fn main() {
+fn main() -> Result<()> {
     let mut chunk = Chunk::default();
 
     chunk.push_constant(1.2, 123);
     chunk.push(OpCode::Return, 123);
 
     chunk.disassemble("test chunk");
+
+    let mut vm = VM::new(chunk);
+    vm.interpret()?;
+
+    Ok(())
 }
diff --git a/rust/src/vm.rs b/rust/src/vm.rs
new file mode 100644
index 0000000..4f4a2c8
--- /dev/null
+++ b/rust/src/vm.rs
@@ -0,0 +1,37 @@
+use anyhow::Result;
+use thiserror::Error;
+
+use crate::chunk::{Chunk, OpCode};
+
+#[derive(Error, Debug)]
+pub enum InterpretError {
+    #[error("compile error")]
+    Compile,
+    #[error("runtime error")]
+    Runtime,
+}
+
+pub struct VM {
+    chunk: Chunk,
+    ip: usize,
+}
+
+impl VM {
+    pub fn new(chunk: Chunk) -> Self {
+        Self { chunk, ip: 0 }
+    }
+
+    pub fn interpret(&mut self) -> Result<()> {
+        loop {
+            match self.chunk.code[self.ip] {
+                OpCode::Constant(constant) => {
+                    let value = self.chunk.constants[constant];
+                    println!("{}", value);
+                },
+                OpCode::Return => return Ok(()),
+            }
+
+            self.ip += 1;
+        }
+    }
+}