Works :)

src/assembler.rs

@@ -1,13 +1,111 @@
-use crate::parser::Instruction;
+use std::collections::HashMap;
+
+use crate::{
+    parser::{Instruction, Value},
+    Result,
+};
+
+type Function = fn(&mut Assembler, usize);
 
 pub struct Assembler {
-    instruction: Instruction,
+    functions: HashMap<String, Function>,
+    stack: Vec<String>,
+    assembled: Vec<u8>,
+}
+
+trait Assemble {
+    fn assemble(self, assembler: &mut Assembler) -> Result<()>;
+}
+
+impl Assemble for Value {
+    fn assemble(self, assembler: &mut Assembler) -> Result<()> {
+        match self {
+            Self::Instruction(instruction) => instruction.assemble(assembler),
+            Value::IntegerLiteral(v) => {
+                let bytes = v.to_le_bytes();
+
+                assembler.push(v.to_string());
+
+                assembler.add_instruction(&[0x68]);
+                assembler.add_instruction(&bytes);
+
+                Ok(())
+            }
+            _ => todo!()
+        }
+    }
+}
+
+impl Assemble for Instruction {
+    fn assemble(self, assembler: &mut Assembler) -> Result<()> {
+        let n_arguments = self.arguments.len();
+
+        for argument in self.arguments {
+            argument.assemble(assembler)?;
+        }
+
+        let function = match assembler.functions.get(&self.name) {
+            Some(v) => v,
+            None => return Err(crate::Error::UndefinedIdentifier(self.name))
+        };
+
+        function(assembler, n_arguments);
+
+        Ok(())
+    }
 }
 
 impl Assembler {
-    pub fn assemble(instruction: Instruction) -> Vec<u8> {
-        let assembler = Assembler { instruction };
+    pub fn assemble(instruction: Instruction) -> Result<Vec<u8>> {
+        let mut assembler = Self {
+            functions: Self::default_functions(),
+            stack: Vec::new(),
+            assembled: Vec::new(),
+        };
+        instruction.assemble(&mut assembler)?;
+        Ok(assembler.assembled)
+    }
 
-        todo!()
+    fn add_instruction(&mut self, instruction: &[u8]) {
+        self.assembled.extend_from_slice(instruction);
+    }
+
+    fn push(&mut self, identifier: String) {
+        self.stack.push(identifier);
+    }
+
+    fn pop(&mut self) {
+        self.stack.pop();
+    }
+
+    fn get_stack_location(&self, identifier: &str) -> Option<u32> {
+        self.stack
+            .iter()
+            .position(|x| x == identifier)
+            .map(|x| x as u32)
+    }
+
+    fn default_functions() -> HashMap<String, Function> {
+        let mut map: HashMap<String, Function> = HashMap::new();
+
+        map.insert(
+            "+".to_string(),
+            |assembler, n_arguments| {
+                if n_arguments != 2 { todo!() }
+
+                assembler.add_instruction(&[0x58]); // Pop EAX
+                assembler.pop();
+
+                assembler.add_instruction(&[0x03, 0x04, 0x24]); // add (%esp), %eax
+
+                assembler.add_instruction(&[0x5B]); // Pop EBX
+                assembler.pop();
+
+                assembler.add_instruction(&[0x50]); // Push EAX
+                assembler.push("".to_string());
+            },
+        );
+
+        map
     }
 }

src/error.rs

@@ -1,6 +1,7 @@
 #[derive(Clone, Debug, Hash)]
 pub enum Error {
     SyntaxError(SyntaxError),
+    UndefinedIdentifier(String),
 }
 
 #[derive(Clone, Debug, Hash)]
@@ -16,6 +17,7 @@ impl std::fmt::Display for Error {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
             Error::SyntaxError(e) => write!(f, "Error at: {}:{}. {}", e.row, e.column, e.message),
+            Error::UndefinedIdentifier(e) => write!(f, "Error: undefined identifier: {e}"),
         }
     }
 }

src/main.rs

@@ -6,7 +6,14 @@ mod error;
 pub use error::*;
 
 fn main() {
-    let code = "(+ 1 2)".to_string();
+    let code = "(+ 1 (+ 5 5))".to_string();
 
-    dbg!(parser::Parser::parse(code).unwrap());
+    let parsed = dbg!(parser::Parser::parse(code).unwrap());
+    let assembled = assembler::Assembler::assemble(parsed).unwrap();
+
+    for byte in assembled {
+        print!("{byte:#X}, ");
+    }
+
+    println!("");
 }

src/parser.rs

@@ -7,17 +7,17 @@ pub struct Parser {
     lines: Vec<Vec<char>>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub(crate) struct Instruction {
-    name: String,
-    arguments: Vec<Value>,
+    pub name: String,
+    pub arguments: Vec<Value>,
 }
 
-#[derive(Debug)]
-enum Value {
+#[derive(Debug, Clone)]
+pub(crate) enum Value {
     Instruction(Instruction),
     StringLiteral(String),
-    IntegerLiteral(usize),
+    IntegerLiteral(u32),
     Identifier(String),
 }
 
@@ -105,7 +105,7 @@ impl Parser {
         Ok(accumulator)
     }
 
-    fn integer_literal(&mut self) -> Result<usize> {
+    fn integer_literal(&mut self) -> Result<u32> {
         let mut accumulator = String::new();
 
         while self.lines[self.row][self.column].is_numeric() {
@@ -115,7 +115,7 @@ impl Parser {
 
         self.jump_whitespace();
 
-        match accumulator.parse::<usize>() {
+        match accumulator.parse() {
             Ok(v) => Ok(v),
             Err(_e) => Err(Error::SyntaxError(SyntaxError {
                 row: self.row,