Revert "Use std::optional<bool> instead of OptionalBool"

This reverts commit ba879a882e.

src/utils/optional_bool.cpp

@@ -1,8 +1,8 @@
 #include <utils/optional_bool.hpp>
 
 
-std::ostream& operator<<(std::ostream& os, const std::optional<bool>& o)
+std::ostream& operator<<(std::ostream& os, const OptionalBool& o)
 {
-  os << std::to_string(o);
+  os << o.to_string();
   return os;
 }

src/utils/optional_bool.hpp

@@ -1,21 +1,37 @@
 #pragma once
 
-#include <optional>
-
 #include <string>
 
-namespace std
+struct OptionalBool
 {
-inline
-std::string to_string(const std::optional<bool> b)
-{
-  if (!b)
-    return "unset";
-  else if (*b)
-    return "true";
-  else
-    return "false";
-}
-}
+  OptionalBool() = default;
 
-std::ostream& operator<<(std::ostream& os, const std::optional<bool>& o);
+  OptionalBool(bool value):
+  is_set(true), value(value) {}
+
+  void set_value(bool value)
+  {
+    this->is_set = true;
+    this->value = value;
+  }
+
+  void unset()
+  {
+    this->is_set = false;
+  }
+
+  std::string to_string() const
+  {
+    if (this->is_set == false)
+      return "unset";
+    else if (this->value)
+      return "true";
+    else
+      return "false";
+  }
+
+  bool is_set{false};
+  bool value{false};
+};
+
+std::ostream& operator<<(std::ostream& os, const OptionalBool& o);