diff --git a/cclox_src/object.cc b/cclox_src/object.cc
index 32560a6..db516e6 100644
--- a/cclox_src/object.cc
+++ b/cclox_src/object.cc
@@ -1,18 +1,28 @@
 #include "object.hh"
 
-void Identifier::write(std::ostream &os) const {
-  os << identifier;
-};
-
-void StringLit::write(std::ostream &os) const {
-  os << literal;
-};
-
-void Number::write(std::ostream &os) const {
-  os << number;
-};
+Object::Object(StringObjectType string_type, const std::string &value) : str{value} {
+  switch (string_type) {
+    case StringObjectType::IDENTIFIER:
+      type = ObjectType::IDENTIFIER;
+      break;
+    case StringObjectType::LITERAL:
+      type = ObjectType::STRING_LIT;
+      break;
+  }
+}
 
 std::ostream &operator<<(std::ostream &os, const Object &obj) {
-  obj.write(os);
+  switch (obj.type) {
+    case ObjectType::NIL:
+      break;
+    case ObjectType::IDENTIFIER:
+    case ObjectType::STRING_LIT:
+      os << obj.str;
+      break;
+    case ObjectType::NUMBER:
+      os << obj.number;
+      break;
+  }
+
   return os;
 }
diff --git a/cclox_src/object.hh b/cclox_src/object.hh
index fd59666..6dfdca1 100644
--- a/cclox_src/object.hh
+++ b/cclox_src/object.hh
@@ -1,27 +1,31 @@
 #pragma once
 
-#include <string>
+#include <cstdint>
 #include <iostream>
+#include <string_view>
+
+enum class StringObjectType : uint8_t {
+  IDENTIFIER,
+  LITERAL,
+};
+
+enum class ObjectType : uint8_t {
+  NIL,
+  IDENTIFIER,
+  STRING_LIT,
+  NUMBER,
+};
 
 struct Object {
-  Object() = delete;
-  virtual ~Object() = default;
-  virtual void write(std::ostream &os) const = 0;
-};
+  Object() : type{ObjectType::NIL} {};
+  Object(double number) : type{ObjectType::NUMBER}, number{number} {};
+  Object(StringObjectType string_type, const std::string &value);
 
-struct Identifier : public Object {
-  virtual void write(std::ostream &os) const final;
-  std::string identifier;
-};
-
-struct StringLit : public Object {
-  virtual void write(std::ostream &os) const final;
-  std::string literal;
-};
-
-struct Number : public Object {
-  virtual void write(std::ostream &os) const final;
-  double number;
+  ObjectType type;
+  union {
+    std::string_view str;
+    double number;
+  };
 };
 
 std::ostream &operator<<(std::ostream &os, const Object &obj);
diff --git a/cclox_src/scanner.cc b/cclox_src/scanner.cc
index 68259aa..dc62654 100644
--- a/cclox_src/scanner.cc
+++ b/cclox_src/scanner.cc
@@ -1,7 +1,53 @@
 #include "scanner.hh"
 #include "token.hh"
+#include "error_handler.hh"
+#include "object.hh"
 #include <vector>
 
+extern ErrorHandler error_handler;
+
 std::vector<Token> Scanner::scan_tokens() {
-  return std::vector<Token>{};
+  while (!is_at_end()) {
+    start = current;
+    scan_token();
+  }
+
+  tokens.push_back(Token(TokenType::EOFILE, "", Object{}, line));
+  return tokens;
+}
+
+bool Scanner::is_at_end() {
+  return current >= code.size();
+}
+
+void Scanner::scan_token() {
+  char c = advance();
+  switch (c) {
+    case '(': add_token(TokenType::LEFT_PAREN); break;
+    case ')': add_token(TokenType::RIGHT_PAREN); break;
+    case '{': add_token(TokenType::LEFT_BRACE); break;
+    case '}': add_token(TokenType::RIGHT_BRACE); break;
+    case ',': add_token(TokenType::COMMA); break;
+    case '.': add_token(TokenType::DOT); break;
+    case '-': add_token(TokenType::MINUS); break;
+    case '+': add_token(TokenType::PLUS); break;
+    case ';': add_token(TokenType::SEMICOLON); break;
+    case '*': add_token(TokenType::STAR); break;
+    default:
+      error_handler.error(line, "Unexpected character.");
+      break;
+  }
+}
+
+char Scanner::advance() {
+  return code.at(current++);
+}
+
+void Scanner::add_token(TokenType type) {
+  add_token(type, Object{});
+}
+
+void Scanner::add_token(TokenType type, Object literal) {
+  std::string text = code.substr(start, current - start);
+  tokens.push_back(Token(type, text, literal, line));
 }
diff --git a/cclox_src/scanner.hh b/cclox_src/scanner.hh
index ae24ce1..5931a4f 100644
--- a/cclox_src/scanner.hh
+++ b/cclox_src/scanner.hh
@@ -1,11 +1,19 @@
 #pragma once
 
 #include "token.hh"
+#include <cstddef>
 #include <vector>
 
 struct Scanner {
-  Scanner(const std::string &code) : code{code} {};
+  Scanner(const std::string &code) : code{code}, tokens{}, start{0}, current{0}, line{1} {};
   std::vector<Token> scan_tokens();
+  bool is_at_end();
+  void scan_token();
+  char advance();
+  void add_token(TokenType type);
+  void add_token(TokenType type, Object literal);
 
   std::string code;
+  std::vector<Token> tokens;
+  std::size_t start, current, line;
 };
diff --git a/cclox_src/token.cc b/cclox_src/token.cc
index a60b490..8c92041 100644
--- a/cclox_src/token.cc
+++ b/cclox_src/token.cc
@@ -1,5 +1,133 @@
 #include "token.hh"
+#include <stdint.h>
+
+std::ostream &operator<<(std::ostream &os, const TokenType &type) {
+  switch (type) {
+    case TokenType::LEFT_PAREN:
+      os << "TokenType::LEFT_PAREN";
+      break;
+    case TokenType::RIGHT_PAREN:
+      os << "TokenType::RIGHT_PAREN";
+      break;
+    case TokenType::LEFT_BRACE:
+      os << "TokenType::LEFT_BRACE";
+      break;
+    case TokenType::RIGHT_BRACE:
+      os << "TokenType::RIGHT_BRACE";
+      break;
+    case TokenType::COMMA:
+      os << "TokenType::COMMA";
+      break;
+    case TokenType::DOT:
+      os << "TokenType::DOT";
+      break;
+    case TokenType::MINUS:
+      os << "TokenType::MINUS";
+      break;
+    case TokenType::PLUS:
+      os << "TokenType::PLUS";
+      break;
+    case TokenType::SEMICOLON:
+      os << "TokenType::SEMICOLON";
+      break;
+    case TokenType::SLASH:
+      os << "TokenType::SLASH";
+      break;
+    case TokenType::STAR:
+      os << "TokenType::STAR";
+      break;
+    case TokenType::BANG:
+      os << "TokenType::BANG";
+      break;
+    case TokenType::BANG_EQUAL:
+      os << "TokenType::BANG_EQUAL";
+      break;
+    case TokenType::EQUAL:
+      os << "TokenType::EQUAL";
+      break;
+    case TokenType::EQUAL_EQUAL:
+      os << "TokenType::EQUAL_EQUAL";
+      break;
+    case TokenType::GREATER:
+      os << "TokenType::GREATER";
+      break;
+    case TokenType::GREATER_EQUAL:
+      os << "TokenType::GREATER_EQUAL";
+      break;
+    case TokenType::LESS:
+      os << "TokenType::LESS";
+      break;
+    case TokenType::LESS_EQUAL:
+      os << "TokenType::LESS_EQUAL";
+      break;
+    case TokenType::IDENTIFIER:
+      os << "TokenType::IDENTIFIER";
+      break;
+    case TokenType::STRING:
+      os << "TokenType::STRING";
+      break;
+    case TokenType::NUMBER:
+      os << "TokenType::NUMBER";
+      break;
+    case TokenType::AND:
+      os << "TokenType::AND";
+      break;
+    case TokenType::CLASS:
+      os << "TokenType::CLASS";
+      break;
+    case TokenType::ELSE:
+      os << "TokenType::ELSE";
+      break;
+    case TokenType::FALSE:
+      os << "TokenType::FALSE";
+      break;
+    case TokenType::FUN:
+      os << "TokenType::FUN";
+      break;
+    case TokenType::FOR:
+      os << "TokenType::FOR";
+      break;
+    case TokenType::IF:
+      os << "TokenType::IF";
+      break;
+    case TokenType::NIL:
+      os << "TokenType::NIL";
+      break;
+    case TokenType::OR:
+      os << "TokenType::OR";
+      break;
+    case TokenType::PRINT:
+      os << "TokenType::PRINT";
+      break;
+    case TokenType::RETURN:
+      os << "TokenType::RETURN";
+      break;
+    case TokenType::SUPER:
+      os << "TokenType::SUPER";
+      break;
+    case TokenType::THIS:
+      os << "TokenType::THIS";
+      break;
+    case TokenType::TRUE:
+      os << "TokenType::TRUE";
+      break;
+    case TokenType::VAR:
+      os << "TokenType::VAR";
+      break;
+    case TokenType::WHILE:
+      os << "TokenType::WHILE";
+      break;
+    case TokenType::EOFILE:
+      os << "TokenType::EOFILE";
+      break;
+  }
+
+  return os;
+}
 
 std::ostream &operator<<(std::ostream &os, const Token &token) {
-  return os << uint8_t(token.type) << ' ' << token.lexeme << ' ' << token.literal;
+  os << token.type << ' ';
+  os << token.lexeme << ' ';
+  os << token.literal;
+  return os;
 }
diff --git a/cclox_src/token.hh b/cclox_src/token.hh
index 4f3e88e..16d86d2 100644
--- a/cclox_src/token.hh
+++ b/cclox_src/token.hh
@@ -26,14 +26,15 @@ enum class TokenType : uint8_t {
 };
 
 struct Token {
-  Token(TokenType type, const std::string &lexeme, Object &literal, int line)
+  Token(TokenType type, const std::string &lexeme, Object literal, int line)
     : type{type}, lexeme{lexeme}, literal{literal}, line{line}
   {};
 
   TokenType type;
   std::string lexeme;
-  Object &literal;
+  Object literal;
   int line;
 };
 
+std::ostream &operator<<(std::ostream &os, const TokenType &type);
 std::ostream &operator<<(std::ostream &os, const Token &token);