maybe a simpler unique_ptr

2022/25.cpp

@@ -13,6 +13,8 @@
 
 namespace {
 
+using It = std::istream_iterator<std::string>;
+
 // 
 template <typename T>
 auto DivMod(T dividend, T divisor) -> std::pair<T, T>
@@ -59,8 +61,7 @@ auto ToInt(std::string const& str) -> T
 
 auto Solve(std::istream & in) -> std::string
 {
-  using It = std::istream_iterator<std::string>;
-  return FromInt(std::transform_reduce(It(in), It(), 0, std::plus(), ToInt<std::int64_t>));
+  return FromInt(std::transform_reduce(It{in}, It{}, std::int64_t{}, std::plus(), ToInt<std::int64_t>));
 }
 
 } // namespace

lib/include/aocpp/Startup.hpp

@@ -8,17 +8,7 @@
 
 namespace aocpp {
 
-class ConditionalDeleter {
-  bool should_delete_;
-
-public:
-  ConditionalDeleter(bool should_delete) : should_delete_ {should_delete} {}
-  
-  template <typename T>
-  auto operator()(T * pointer) -> void { if (should_delete_) { delete pointer; }}
-};
-
-auto Startup(int argc, char ** argv) -> std::unique_ptr<std::istream, ConditionalDeleter>;
+auto Startup(int argc, char ** argv) -> std::unique_ptr<std::istream, void(*)(std::istream*)>;
 
 }
 

lib/src/Startup.cpp

@@ -12,29 +12,20 @@
 
 namespace aocpp {
 
-auto Startup(int argc, char ** argv) -> std::unique_ptr<std::istream, ConditionalDeleter> {
+auto Startup(int argc, char ** argv) -> std::unique_ptr<std::istream, void(*)(std::istream*)> {
   if (std::getenv("DOCTEST")) {
     exit(doctest::Context{argc, argv}.run());
   }
 
-  bool should_delete;
-  std::istream* result_ptr;
-
   switch (argc) {
     case 2:
-      should_delete = true;
-      result_ptr = new std::ifstream{argv[1]};
-      break;
+      return {new std::ifstream{argv[1]}, [](std::istream* p) { delete p; }};
     case 1:
-      should_delete = false;
-      result_ptr = &std::cin;
-      break;
+      return {&std::cin, [](std::istream*){}};
     default:
       std::cerr << "bad arguments\n";
       exit(EXIT_FAILURE);
   }
-
-  return {result_ptr, should_delete};
 }
 
 }