Big things coming

src/code_gen.rs

@@ -0,0 +1,183 @@
+use std::{collections::HashMap, ops::AddAssign};
+
+use color_eyre::eyre::Error;
+
+use crate::{
+    lexer::Keyword,
+    parser::{LispAtom, SExpression},
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum InstructionFrom {
+    ROM,
+    RAM,
+    ALU,
+    RegisterC,
+    RegisterD,
+
+    RegisterSP,
+    RegisterSB,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+enum InstructionTo {
+    JumpAddressUpper,
+    JumpAddressLower,
+
+    Jump,
+
+    RamAddressUpper,
+    RamAddressLower,
+
+    RAM,
+
+    Flags,
+
+    RegisterA,
+    RegisterB,
+    RegisterC,
+    RegisterD,
+
+    RegisterSP,
+    RegisterSB,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+struct Command {
+    data_from: InstructionFrom,
+    data_to: InstructionTo,
+    data: i8,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Scope {
+    variables: Vec<String>,
+    stack_position: usize,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct EightBitLang {
+    instructions: Vec<Command>,
+    labels: Option<HashMap<String, usize>>,
+}
+
+pub trait GenerateCode {
+    fn to_code(self, codegen_scope: &mut Scope) -> Result<EightBitLang, Self::Error>
+    where
+        Self: Sized;
+
+    type Error;
+}
+
+impl GenerateCode for SExpression {
+    fn to_code(self, codegen_scope: &mut Scope) -> Result<EightBitLang, Self::Error> {
+        match self {
+            SExpression::Atom(a) => a.to_code(codegen_scope),
+            _ => todo!(),
+        }
+    }
+
+    type Error = Error;
+}
+
+impl GenerateCode for LispAtom {
+    fn to_code(self, codegen_scope: &mut Scope) -> Result<EightBitLang, Self::Error> {
+        match self {
+            LispAtom::Keyword(keyword) => keyword.to_code(codegen_scope),
+            LispAtom::Integer(number) => number.to_code(codegen_scope),
+            _ => todo!(),
+        }
+    }
+
+    type Error = Error;
+}
+
+impl GenerateCode for isize {
+    fn to_code(self, codegen_scope: &mut Scope) -> Result<EightBitLang, Self::Error> {
+        if let Err(_e) = i8::try_from(self) {
+            return Err(Error::msg("Yo integer too big brah"));
+        }
+
+        return Ok(EightBitLang::push(self as i8, codegen_scope));
+    }
+
+    type Error = Error;
+}
+
+impl GenerateCode for Keyword {
+    fn to_code(self, _codegen_scope: &mut Scope) -> Result<EightBitLang, Self::Error> {
+        match self {
+            _ => todo!(),
+        }
+    }
+
+    type Error = Error;
+}
+
+impl AddAssign for EightBitLang {
+    fn add_assign(&mut self, mut rhs: Self) {
+        let mut labels = self.labels.clone().unwrap();
+        if rhs.labels.is_some() || self.labels.is_some() {
+            if self.labels.is_none() {
+                labels = rhs.labels.unwrap();
+            } else if rhs.labels.is_none() {
+            } else {
+                labels = HashMap::new();
+                for label in rhs.labels.unwrap() {
+                    labels.insert(label.0, label.1 + self.instructions.len());
+                }
+            }
+            self.labels = Some(labels);
+        }
+        self.instructions.append(&mut rhs.instructions);
+    }
+}
+
+impl From<Command> for EightBitLang {
+    fn from(value: Command) -> Self {
+        Self {
+            instructions: vec![value],
+            labels: None,
+        }
+    }
+}
+
+impl EightBitLang {
+    fn push(value: i8, codegen_scope: &mut Scope) -> Self {
+        use InstructionFrom as IF;
+        use InstructionTo as IT;
+
+        codegen_scope.stack_position += 1;
+
+        let mut commands = Vec::new();
+        commands.push(Command::new(IF::RegisterSP, IT::RegisterA, 0x00));
+        commands.push(Command::new(IF::ROM, IT::RegisterB, 0x01));
+        commands.push(Command::new(IF::ALU, IT::RegisterSP, 0x00));
+        commands.push(Command::new(IF::RegisterSP, IT::RamAddressLower, 0x00));
+        commands.push(Command::new(IF::ROM, IT::RAM, value));
+
+        Self {
+            instructions: commands,
+            labels: None,
+        }
+    }
+}
+
+impl Command {
+    fn new(data_from: InstructionFrom, data_to: InstructionTo, data: i8) -> Self {
+        Self {
+            data_from,
+            data_to,
+            data,
+        }
+    }
+}
+
+impl Scope {
+    pub fn new() -> Self {
+        Self {
+            variables: Vec::new(),
+            stack_position: 0,
+        }
+    }
+}

src/ir.rs

@@ -0,0 +1,253 @@
+use std::{
+    collections::HashMap,
+    ops::{Add, AddAssign},
+};
+
+use color_eyre::eyre::Error;
+
+use crate::{
+    lexer::{Keyword, Macro},
+    parser::{LispAtom, SExpression, NIL},
+};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct IRepr {
+    commands: Vec<Command>,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+enum Command {
+    PushInt(isize),
+    PushSum,
+    PopR1,
+    PopR2,
+    PopOut,
+    PushRelative(usize),
+
+    Enter,
+    Leave,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Scope {
+    stack_position: usize,
+    stack_positions: Vec<usize>,
+    variables: HashMap<String, usize>,
+}
+
+pub fn generate_code(expressions: Vec<SExpression>) -> Result<IRepr, Error> {
+    let mut scope = Scope {
+        stack_position: 0,
+        stack_positions: vec![],
+        variables: HashMap::new(),
+    };
+
+    let mut sum = IRepr::new();
+
+    for expression in expressions {
+        sum += expression.to_irepr(&mut scope)?
+    }
+
+    Ok(sum)
+}
+
+trait ToIR {
+    fn to_irepr(self, ir_scope: &mut Scope) -> Result<IRepr, Error>;
+}
+
+trait ToIRMacro {
+    fn to_irepr(self, ir_scope: &mut Scope, expressions: SExpression) -> Result<IRepr, Error>;
+}
+
+impl ToIR for SExpression {
+    fn to_irepr(self, ir_scope: &mut Scope) -> Result<IRepr, Error> {
+        Ok(match self {
+            Self::Atom(a) => a.to_irepr(ir_scope)?,
+            Self::Pair(a, b) => match *a {
+                Self::Atom(LispAtom::Macro(m)) => m.to_irepr(ir_scope, *b)?,
+                a => b.to_irepr(ir_scope)? + a.to_irepr(ir_scope)?,
+            },
+        })
+    }
+}
+
+impl ToIR for LispAtom {
+    fn to_irepr(self, ir_scope: &mut Scope) -> Result<IRepr, Error> {
+        match self {
+            Self::Integer(number) => number.to_irepr(ir_scope),
+            Self::Keyword(keyword) => keyword.to_irepr(ir_scope),
+            Self::Identifier(identifier) => {
+                if !ir_scope.variables.contains_key(&identifier) {
+                    todo!();
+                }
+                ir_scope.stack_position += 1;
+                Ok(IRepr {
+                    commands: vec![
+                        Command::PushRelative(ir_scope.variables[&identifier]),
+                    ]
+                })
+            }
+            _ => todo!(),
+        }
+    }
+}
+
+impl ToIR for Keyword {
+    fn to_irepr(self, ir_scope: &mut Scope) -> Result<IRepr, Error> {
+        match self {
+            Self::Nil => Ok(IRepr { commands: vec![] }),
+            Self::Add => {
+                ir_scope.stack_position -= 1;
+                Ok(IRepr {
+                    commands: vec![Command::PopR1, Command::PopR2, Command::PushSum],
+                })
+            }
+            Self::Out => {
+                ir_scope.stack_position -= 1;
+                Ok(IRepr {
+                    commands: vec![Command::PopOut],
+                })
+            }
+        }
+    }
+}
+
+impl ToIR for isize {
+    fn to_irepr(self, ir_scope: &mut Scope) -> Result<IRepr, Error> {
+        ir_scope.stack_position += 1;
+        return Ok(Command::PushInt(self).to_irepr());
+    }
+}
+
+impl ToIRMacro for Macro {
+    fn to_irepr(self, ir_scope: &mut Scope, expression: SExpression) -> Result<IRepr, Error> {
+        match self {
+            Self::Let => {
+                println!("Parsing a let expression");
+                let (mut varlist, mut body) = match expression {
+                    SExpression::Atom(_a) => todo!(),
+                    SExpression::Pair(a, b) => (*a, *b),
+                };
+
+                let mut commands = IRepr {
+                    commands: vec![Command::Enter],
+                };
+
+                ir_scope.stack_positions.push(ir_scope.stack_position);
+                ir_scope.stack_position = 0;
+
+                while varlist != NIL {
+                    let var = match varlist {
+                        SExpression::Atom(_) => panic!("Let defined wrong"),
+                        SExpression::Pair(a, b) => {
+                            varlist = *b;
+                            *a
+                        }
+                    };
+                    match var {
+                        SExpression::Atom(a) => {
+                            let name = match a {
+                                LispAtom::Identifier(ident) => ident,
+                                _ => todo!(),
+                            };
+                            ir_scope.variables.insert(name, ir_scope.stack_position);
+                            ir_scope.stack_position += 1;
+                            commands += Command::PushInt(0);
+                        }
+                        SExpression::Pair(name, car) => {
+                            let name = match *name {
+                                SExpression::Atom(a) => match a {
+                                    LispAtom::Identifier(ident) => ident,
+                                    _ => todo!(),
+                                },
+                                _ => todo!(),
+                            };
+                            commands += car.to_irepr(ir_scope)?;
+                            ir_scope.variables.insert(name, ir_scope.stack_position);
+                        }
+                    }
+                }
+
+                dbg!(&commands);
+                dbg!(&ir_scope);
+
+                while body != NIL {
+                    match body {
+                        SExpression::Atom(_a) => todo!(),
+                        SExpression::Pair(a, b) => {
+                            commands += a.to_irepr(ir_scope)?;
+                            body = *b;
+                        }
+                    }
+                }
+
+                dbg!(&commands);
+                dbg!(&ir_scope);
+                
+                commands += Command::Leave;
+
+                todo!()
+            }
+            _ => todo!(),
+        }
+    }
+}
+
+impl Command {
+    fn to_irepr(self) -> IRepr {
+        IRepr {
+            commands: vec![self],
+        }
+    }
+}
+
+impl IRepr {
+    fn new() -> IRepr {
+        return IRepr { commands: vec![] };
+    }
+}
+
+impl AddAssign for IRepr {
+    fn add_assign(&mut self, rhs: Self) {
+        self.commands.extend(rhs.commands);
+    }
+}
+
+impl AddAssign<Vec<Command>> for IRepr {
+    fn add_assign(&mut self, rhs: Vec<Command>) {
+        self.commands.extend(rhs);
+    }
+}
+
+impl Add<Vec<Command>> for IRepr {
+    fn add(mut self, rhs: Vec<Command>) -> Self::Output {
+        self += rhs;
+        return self;
+    }
+
+    type Output = Self;
+}
+
+impl AddAssign<Command> for IRepr {
+    fn add_assign(&mut self, rhs: Command) {
+        self.commands.push(rhs);
+    }
+}
+
+impl Add<Command> for IRepr {
+    fn add(mut self, rhs: Command) -> Self::Output {
+        self += rhs;
+        return self;
+    }
+
+    type Output = Self;
+}
+
+impl Add for IRepr {
+    fn add(mut self, rhs: Self) -> Self::Output {
+        self += rhs;
+        return self;
+    }
+
+    type Output = Self;
+}

src/lexer.rs

@@ -1,27 +1,43 @@
-use std::str::FromStr;
+use std::{fmt::Display, str::FromStr};
 
 use thiserror::Error;
 
-#[derive(Debug)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub enum TokenType {
     OpenParantheses,
     ClosedParantheses,
-    Integer(usize),
+    Dot,
+    Integer(isize),
     String(String),
     Identifier(String),
+    Keyword(Keyword),
+    Macro(Macro),
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Token {
-    row: usize,
+    pub row: usize,
-    col: usize,
+    pub col: usize,
 
-    token_type: TokenType,
+    pub token_type: TokenType,
 }
 
 #[derive(Debug)]
 pub struct TokenString {
-    tokens: Vec<Token>,
+    pub tokens: Vec<Token>,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Keyword {
+    Add,
+    Out,
+    Nil,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum Macro {
+    Let,
+    Defun,
 }
 
 #[derive(Debug)]
@@ -38,9 +54,9 @@ struct UnfinishedTokenString {
 #[derive(Error, Debug)]
 #[error("Syntax error at: {row}:{col}. {message}")]
 pub struct LexerError {
-    row: usize,
+    pub row: usize,
-    col: usize,
+    pub col: usize,
-    message: String,
+    pub message: String,
 }
 
 impl FromStr for TokenString {
@@ -51,7 +67,7 @@ impl FromStr for TokenString {
             tokens: Vec::new(),
             eof: false,
 
-            row: 0,
+            row: 1,
             col: 1,
         };
 
@@ -84,10 +100,12 @@ impl Lexer for UnfinishedTokenString {
             use TokenType as TT;
 
             let token_type = match self.input[self.position] as char {
-                '(' => Ok(TT::OpenParantheses),
+                '(' => { self.next_char(); Ok(TT::OpenParantheses) },
-                ')' => Ok(TT::ClosedParantheses),
+                ')' => { self.next_char(); Ok(TT::ClosedParantheses) },
-                'a'..='z' | 'A'..='Z' => Ok(TT::Identifier(self.lex_identifier())),
+                '.' => { self.next_char(); Ok(TT::Dot) },
+                'a'..='z' | 'A'..='Z' | ':' => Ok(self.lex_identifier()),
                 '0'..='9' | '-' => Ok(TT::Integer(self.lex_integer())),
+                '"' => Ok(TT::String(self.lex_string())),
                 v => Err(format!("Expected new token, found: {v}")),
             };
 
@@ -107,8 +125,6 @@ impl Lexer for UnfinishedTokenString {
             };
 
             self.tokens.push(token);
-
-            self.next_char();
             self.skip_whitespace();
         }
 
@@ -140,11 +156,61 @@ impl UnfinishedTokenString {
         }
     }
 
-    fn lex_identifier(&mut self) -> String {
+    fn lex_identifier(&mut self) -> TokenType {
-        todo!()
+        let mut ident: String = String::new();
+        while !self.eof && self.input[self.position].is_ascii_alphanumeric() {
+            ident += &String::from_utf8_lossy(&[self.input[self.position]]);
+            self.next_char();
+        }
+
+        use Keyword as K;
+        use Macro as M;
+        use TokenType as TT;
+        match ident.as_str() {
+            "add" => TT::Keyword(K::Add),
+            "out" => TT::Keyword(K::Out),
+            "nil" => TT::Keyword(K::Nil),
+            "let" => TT::Macro(M::Let),
+            "defun" => TT::Macro(M::Defun),
+            _ => TT::Identifier(ident),
+        }
     }
 
-    fn lex_integer(&mut self) -> usize {
+    fn lex_integer(&mut self) -> isize {
-        todo!()
+        let mut number: String = String::new();
+        while !self.eof && self.input[self.position].is_ascii_digit() {
+            number += &String::from_utf8_lossy(&[self.input[self.position]]);
+            self.next_char();
+        }
+        number.parse().unwrap()
+    }
+
+    fn lex_string(&mut self) -> String {
+        let mut string: String = String::new();
+        self.next_char();
+        while !self.eof && !(self.input[self.position] == '"' as u8) {
+            string += &String::from_utf8_lossy(&[self.input[self.position]]);
+            self.next_char();
+        }
+        string
+    }
+}
+
+impl Display for Keyword {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Add => write!(f, "add"),
+            Self::Nil => write!(f, "nil"),
+            Self::Out => write!(f, "out"),
+        }
+    }
+}
+
+impl Display for Macro {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Let => write!(f, "let"),
+            Self::Defun => write!(f, "defun"),
+        }
     }
 }

src/main.rs

@@ -1,32 +1,47 @@
 // mod assembler;
+mod code_gen;
+mod ir;
 mod lexer;
-// mod parser;
+mod parser;
 
 mod error;
 
 use color_eyre::eyre::Result;
 // pub use error::*;
+use ir::IRepr;
 use lexer::TokenString;
+use parser::SExpression;
+
+use crate::{
+    code_gen::{EightBitLang, GenerateCode, Scope},
+    ir::generate_code,
+};
 
 fn main() -> Result<()> {
     // let code = "(+ 1 (+ 5 5))".to_string();
     color_eyre::install()?;
 
-    let code = "()".to_string();
+    // let code = r#"(mul 2 (add 3 4))"#.to_string();
 
-    let lexed: TokenString = code.parse()?;
+    // let code = "(add 3 4) (add 1 2)";
+    let code = "(let ((a 3)) (out (add 1 a)) (out (add 2 a)))";
 
-    dbg!(lexed);
+    let lexed: TokenString = dbg!((code.parse())?);
 
-    Ok(())
+    let parsed: Vec<SExpression> = (lexed.try_into())?;
+    println!("{parsed:?}");
 
+    let code: IRepr = generate_code(parsed)?;
+
+    // let code: EightBitLang = code.to_code(&mut Scope::new())?;
+
+    dbg!(code);
     /*
-    let parsed = dbg!(parser::Parser::parse(code).unwrap());
-    let assembled = assembler::Assembler::assemble(parsed).unwrap();
 
     for byte in assembled {
         print!("{byte:#X}, ");
     }
 
     println!(""); */
+    Ok(())
 }

src/parser.rs

@@ -1,143 +1,134 @@
-use crate::*;
+use std::fmt::Display;
 
-#[derive(Debug)]
+use color_eyre::eyre::Error;
-pub struct Parser {
+
-    row: usize,
+use crate::lexer::{Keyword, Macro, Token, TokenString, TokenType};
-    column: usize,
+
-    lines: Vec<Vec<char>>,
+pub static NIL: SExpression = SExpression::Atom(LispAtom::Keyword(Keyword::Nil));
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum SExpression {
+    Pair(Box<SExpression>, Box<SExpression>),
+    Atom(LispAtom),
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) struct Instruction {
+struct State {
-    pub name: String,
+    expression: Vec<Token>,
-    pub arguments: Vec<Value>,
+    index: usize,
+    _functions: Vec<String>,
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq, Eq)]
-pub(crate) enum Value {
+pub enum LispAtom {
-    Instruction(Instruction),
+    Integer(isize),
-    StringLiteral(String),
+    String(String),
-    IntegerLiteral(u32),
     Identifier(String),
+    Keyword(Keyword),
+    Macro(Macro),
 }
 
-impl Parser {
+impl TryFrom<TokenString> for Vec<SExpression> {
-    pub fn parse(stream: String) -> Result<Instruction> {
+    fn try_from(value: TokenString) -> Result<Self, Self::Error> {
-        let mut parser = Parser {
+        let list = value.tokens;
-            row: 0,
+
-            column: 0,
+        let mut expressions = vec![];
-            lines: stream
+
-                .split('\n')
+        let mut state = State {
-                .map(|a| a.chars().collect::<Vec<_>>())
+            expression: list,
-                .collect::<Vec<_>>(),
+            index: 0,
+            _functions: Vec::new(),
         };
-        parser.instruction()
+
+        while state.index != state.expression.len() {
+            expressions.push(SExpression::parse_sexpression(&mut state)?);
+            state.index += 1;
+        }
+
+        Ok(expressions)
     }
 
-    fn increment(&mut self) -> Option<()> {
+    type Error = Error;
-        self.column += 1;
+}
-        if self.column == self.lines[self.row].len() {
+
-            self.row += 1;
+impl SExpression {
-            if self.row == self.lines.len() {
+    fn parse_sexpression(state: &mut State) -> Result<Self, Error> {
-                self.row -= 1;
+        let expr = match &state.expression[state.index].token_type {
-                self.column -= 1;
+            TokenType::OpenParantheses => Self::parse_expression(state),
-                return None;
+            TokenType::Integer(val) => Ok(Self::Atom(LispAtom::Integer(val.to_owned()))),
+            TokenType::String(val) => Ok(Self::Atom(LispAtom::String(val.to_owned()))),
+            TokenType::Identifier(val) => Ok(Self::Atom(LispAtom::Identifier(val.to_owned()))),
+            TokenType::Keyword(val) => Ok(Self::Atom(LispAtom::Keyword(val.to_owned()))),
+            TokenType::Macro(val) => Ok(Self::Atom(LispAtom::Macro(val.to_owned()))),
+            _other => Err(Error::msg(format!(
+                "Did not expect symbol at row {} col {}",
+                state.expression[state.index].row, state.expression[state.index].col
+            ))),
+        };
+
+        dbg!(expr)
+    }
+
+    fn parse_expression(state: &mut State) -> Result<Self, Error> {
+        if state.expression[state.index].token_type != TokenType::OpenParantheses {
+            return Err(Error::msg(format!(
+                "Error: Expected ( at row {} col {}",
+                state.expression[state.index].row, state.expression[state.index].col
+            )));
+        }
+        state.index += 1;
+
+        let expression_1 = dbg!(Self::parse_sexpression(state)?);
+        state.index += 1;
+
+        // Is pair
+        if state.expression[state.index].token_type == TokenType::Dot {
+            state.index += 1;
+            let expression_2 = Self::parse_sexpression(state)?;
+            return Ok(Self::Pair(Box::new(expression_1), Box::new(expression_2)));
+        } else {
+            // Is list
+            let mut elements = vec![expression_1];
+
+            while state.expression[state.index].token_type != TokenType::ClosedParantheses {
+                elements.push(Self::parse_sexpression(state)?);
+                state.index += 1;
             }
-            self.column = 0;
-        }
-        return Some(());
-    }
 
-    fn jump_whitespace(&mut self) -> Option<()> {
+            elements.reverse();
-        self.increment()?;
-        while self.lines[self.row][self.column].is_whitespace() {
-            self.increment()?;
-        }
-        Some(())
-    }
 
-    fn instruction(&mut self) -> Result<Instruction> {
+            let pair = Self::make_pair_list(elements);
-        if self.lines[self.row][self.column] != '(' {
+            return Ok(pair);
-            return Err(Error::SyntaxError(SyntaxError {
-                row: self.row,
-                column: self.column,
-                message: "SyntaxError: Expected '('".to_string(),
-            }));
-        }
-
-        self.jump_whitespace();
-
-        let name = self.identifier()?;
-
-        let mut arguments = Vec::new();
-
-        while self.lines[self.row][self.column] != ')' {
-            match self.lines[self.row][self.column] {
-                '\"' => arguments.push(Value::StringLiteral(self.string_literal()?)),
-                '(' => arguments.push(Value::Instruction(self.instruction()?)),
-                character => {
-                    if character.is_numeric() {
-                        arguments.push(Value::IntegerLiteral(self.integer_literal()?));
-                    } else {
-                        arguments.push(Value::Identifier(self.identifier()?));
-                    }
-                }
-            }
-        }
-
-        self.jump_whitespace();
-
-        return Ok(Instruction { name, arguments });
-    }
-
-    fn string_literal(&mut self) -> Result<String> {
-        self.increment();
-
-        let mut accumulator = String::new();
-
-        while self.lines[self.row][self.column] != '"' {
-            accumulator.push(self.lines[self.row][self.column]);
-            self.increment();
-        }
-
-        self.jump_whitespace();
-
-        Ok(accumulator)
-    }
-
-    fn integer_literal(&mut self) -> Result<u32> {
-        let mut accumulator = String::new();
-
-        while self.lines[self.row][self.column].is_numeric() {
-            accumulator.push(self.lines[self.row][self.column]);
-            self.increment();
-        }
-
-        self.jump_whitespace();
-
-        match accumulator.parse() {
-            Ok(v) => Ok(v),
-            Err(_e) => Err(Error::SyntaxError(SyntaxError {
-                row: self.row,
-                column: self.column,
-                message: "Couldn't parse integer literal".to_string(),
-            })),
         }
     }
 
-    fn identifier(&mut self) -> Result<String> {
+    fn make_pair_list(mut expressions: Vec<SExpression>) -> SExpression {
-        let mut accumulator = String::new();
+        if expressions.len() == 1 {
-
+            return SExpression::Pair(Box::new(expressions[0].clone()), Box::new(NIL.clone()));
-        let mut current = self.lines[self.row][self.column];
-
-        while !"()\"".contains(current) && !current.is_whitespace() {
-            accumulator.push(self.lines[self.row][self.column]);
-            self.increment();
-            current = self.lines[self.row][self.column];
         }
 
-        self.jump_whitespace();
+        return SExpression::Pair(
-
+            Box::new(
-        Ok(accumulator)
+                expressions
+                    .pop()
+                    .expect("The length should be more than one"),
+            ),
+            Box::new(Self::make_pair_list(expressions)),
+        );
+    }
+}
+
+impl Display for SExpression {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Pair(a, b) => write!(f, "({a} . {b})"),
+            Self::Atom(a) => match a {
+                LispAtom::String(a) => write!(f, "\"{a}\""),
+                LispAtom::Integer(a) => write!(f, "{a}"),
+                LispAtom::Keyword(a) => write!(f, "{a}"),
+                LispAtom::Identifier(a) => write!(f, "{a}"),
+                LispAtom::Macro(a) => write!(f, "{a}"),
+            },
+        }
     }
 }

src/parser_old.rs

@@ -0,0 +1,143 @@
+use crate::{error::{Error, SyntaxError}, *};
+
+#[derive(Debug)]
+pub struct Parser {
+    row: usize,
+    column: usize,
+    lines: Vec<Vec<char>>,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct Instruction {
+    pub name: String,
+    pub arguments: Vec<Value>,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) enum Value {
+    Instruction(Instruction),
+    StringLiteral(String),
+    IntegerLiteral(u32),
+    Identifier(String),
+}
+
+impl Parser {
+    pub fn parse(stream: String) -> Result<Instruction> {
+        let mut parser = Parser {
+            row: 0,
+            column: 0,
+            lines: stream
+                .split('\n')
+                .map(|a| a.chars().collect::<Vec<_>>())
+                .collect::<Vec<_>>(),
+        };
+        parser.instruction()
+    }
+
+    fn increment(&mut self) -> Option<()> {
+        self.column += 1;
+        if self.column == self.lines[self.row].len() {
+            self.row += 1;
+            if self.row == self.lines.len() {
+                self.row -= 1;
+                self.column -= 1;
+                return None;
+            }
+            self.column = 0;
+        }
+        return Some(());
+    }
+
+    fn jump_whitespace(&mut self) -> Option<()> {
+        self.increment()?;
+        while self.lines[self.row][self.column].is_whitespace() {
+            self.increment()?;
+        }
+        Some(())
+    }
+
+    fn instruction(&mut self) -> Result<Instruction> {
+        if self.lines[self.row][self.column] != '(' {
+            return Err(Error::SyntaxError(SyntaxError {
+                row: self.row,
+                column: self.column,
+                message: "SyntaxError: Expected '('".to_string(),
+            }).into());
+        }
+
+        self.jump_whitespace();
+
+        let name = self.identifier()?;
+
+        let mut arguments = Vec::new();
+
+        while self.lines[self.row][self.column] != ')' {
+            match self.lines[self.row][self.column] {
+                '\"' => arguments.push(Value::StringLiteral(self.string_literal()?)),
+                '(' => arguments.push(Value::Instruction(self.instruction()?)),
+                character => {
+                    if character.is_numeric() {
+                        arguments.push(Value::IntegerLiteral(self.integer_literal()?));
+                    } else {
+                        arguments.push(Value::Identifier(self.identifier()?));
+                    }
+                }
+            }
+        }
+
+        self.jump_whitespace();
+
+        return Ok(Instruction { name, arguments });
+    }
+
+    fn string_literal(&mut self) -> Result<String> {
+        self.increment();
+
+        let mut accumulator = String::new();
+
+        while self.lines[self.row][self.column] != '"' {
+            accumulator.push(self.lines[self.row][self.column]);
+            self.increment();
+        }
+
+        self.jump_whitespace();
+
+        Ok(accumulator)
+    }
+
+    fn integer_literal(&mut self) -> Result<u32> {
+        let mut accumulator = String::new();
+
+        while self.lines[self.row][self.column].is_numeric() {
+            accumulator.push(self.lines[self.row][self.column]);
+            self.increment();
+        }
+
+        self.jump_whitespace();
+
+        match accumulator.parse() {
+            Ok(v) => Ok(v),
+            Err(_e) => Err(Error::SyntaxError(SyntaxError {
+                row: self.row,
+                column: self.column,
+                message: "Couldn't parse integer literal".to_string(),
+            }).into()),
+        }
+    }
+
+    fn identifier(&mut self) -> Result<String> {
+        let mut accumulator = String::new();
+
+        let mut current = self.lines[self.row][self.column];
+
+        while !"()\"".contains(current) && !current.is_whitespace() {
+            accumulator.push(self.lines[self.row][self.column]);
+            self.increment();
+            current = self.lines[self.row][self.column];
+        }
+
+        self.jump_whitespace();
+
+        Ok(accumulator)
+    }
+}