From 47f33f3dc0ce19121077ddf239f11c4f2739cf1a Mon Sep 17 00:00:00 2001
From: haxala1r <eminarslan@emin.software>
Date: Thu, 2 Oct 2025 17:19:51 +0300
Subject: [PATCH] Change lexer code to use an option instead of ignoring the
 variant when no value is needed

---
 src/include/lex.hpp |  3 ++-
 src/lex.cpp         | 16 ++++++++--------
 src/tests/test.cpp  |  4 ++--
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/include/lex.hpp b/src/include/lex.hpp
index 7a4beda..c66b5b0 100644
--- a/src/include/lex.hpp
+++ b/src/include/lex.hpp
@@ -3,6 +3,7 @@
 #include <vector>
 #include <stdint.h>
 #include <variant>
+#include <optional>
 
 enum TokenType {
     OpenParen,
@@ -18,7 +19,7 @@ enum TokenType {
 // Plain Old Data
 struct Token {
     enum TokenType type;
-    std::variant<int64_t, double, std::string> value;
+    std::optional<std::variant<int64_t, double, std::string>> value;
 };
 bool operator==(Token const& one, Token const& other);
 std::ostream &operator<<(std::ostream &os, Token const &t);
diff --git a/src/lex.cpp b/src/lex.cpp
index b90c08c..b8ed457 100644
--- a/src/lex.cpp
+++ b/src/lex.cpp
@@ -12,10 +12,10 @@ std::ostream &operator<<(std::ostream &os, Token const &t) {
     case TokenType::OpenParen: os << "OpenParen)"; break;
     case TokenType::CloseParen: os << "CloseParen)"; break;
     case TokenType::Dollar: os << "Dollar)"; break;
-    case TokenType::Symbol: os << "Symbol, " << get<string>(t.value) << ")"; break;
-    case TokenType::String: os << "String, \"" << get<string>(t.value) << "\")"; break;
-    case TokenType::Int: os << "Int, " << get<int64_t>(t.value) << ")"; break;
-    case TokenType::Double: os << "Double, " << get<double>(t.value) << ")"; break;
+    case TokenType::Symbol: os << "Symbol, " << get<string>(*t.value) << ")"; break;
+    case TokenType::String: os << "String, \"" << get<string>(*t.value) << "\")"; break;
+    case TokenType::Int: os << "Int, " << get<int64_t>(*t.value) << ")"; break;
+    case TokenType::Double: os << "Double, " << get<double>(*t.value) << ")"; break;
     case TokenType::End: os << "END)"; break;
     default:
         os << ")";
@@ -131,14 +131,14 @@ Token Lexer::next() {
         // character while at EOF, even if we have exhausted the stream.
         char c = ss.get();
         if (ss.eof())
-            return {TokenType::End};
+            return {TokenType::End, nullopt};
 
         if (isspace(c))
             continue;
         switch (c) {
-        case '(': return {TokenType::OpenParen};
-        case ')': return {TokenType::CloseParen};
-        case '$': return {TokenType::Dollar};
+        case '(': return {TokenType::OpenParen, nullopt};
+        case ')': return {TokenType::CloseParen, nullopt};
+        case '$': return {TokenType::Dollar, nullopt};
         default:
             ss.unget();
             return lexNonSpecial();
diff --git a/src/tests/test.cpp b/src/tests/test.cpp
index 6db6ca4..dfdb74d 100644
--- a/src/tests/test.cpp
+++ b/src/tests/test.cpp
@@ -6,7 +6,7 @@ TEST_CASE("Lexer lexes doubles correctly", "[Lexer]") {
     
     SECTION("double and negative syntax") {
         Lexer l("(1.0 0.1 -.1 -1. . - -. .-)");
-        REQUIRE(l.next() == Token({OpenParen}));
+        REQUIRE(l.next() == Token({OpenParen, nullopt}));
         REQUIRE(l.next() == Token({Double, 1.0}));
         REQUIRE(l.next() == Token({Double, 0.1}));
         REQUIRE(l.next() == Token({Double, -0.1}));
@@ -15,7 +15,7 @@ TEST_CASE("Lexer lexes doubles correctly", "[Lexer]") {
         REQUIRE(l.next() == Token({Symbol, "-"}));
         REQUIRE(l.next() == Token({Symbol, "-."}));
         REQUIRE(l.next() == Token({Symbol, ".-"}));
-        REQUIRE(l.next() == Token({CloseParen}));
+        REQUIRE(l.next() == Token({CloseParen, nullopt}));
     }
 }