Automatically generate unique id

sunshine/uuid.h

@@ -7,6 +7,7 @@
 
 #include <random>
 
+namespace util {
 union uuid_t {
   std::uint8_t b8[16];
   std::uint16_t b16[8];
@@ -17,7 +18,7 @@ union uuid_t {
     std::uniform_int_distribution<std::uint8_t> dist(0, std::numeric_limits<std::uint8_t>::max());
 
     uuid_t buf;
-    for(auto &el : buf.b8) {
+    for (auto &el : buf.b8) {
       el = dist(engine);
     }
 
@@ -30,11 +31,38 @@ union uuid_t {
   static uuid_t generate() {
     std::random_device r;
 
-    std::default_random_engine engine { r() };
+    std::default_random_engine engine{r()};
 
     return generate(engine);
   }
 
+  [[nodiscard]] std::string string() const {
+    std::string result;
+
+    result.reserve(sizeof(uuid_t) * 2 + 4);
+
+    auto hex = util::hex(*this, true);
+    auto hex_view = hex.to_string_view();
+
+    std::string_view slices[] = {
+      hex_view.substr(0, 8),
+      hex_view.substr(8, 4),
+      hex_view.substr(12, 4),
+      hex_view.substr(16, 4)
+    };
+    auto last_slice = hex_view.substr(20, 12);
+
+    for(auto &slice : slices) {
+      std::copy(std::begin(slice), std::end(slice), std::back_inserter(result));
+
+      result.push_back('-');
+    }
+
+    std::copy(std::begin(last_slice), std::end(last_slice), std::back_inserter(result));
+
+    return result;
+  }
+
   constexpr bool operator==(const uuid_t &other) const {
     return b64[0] == other.b64[0] && b64[1] == other.b64[1];
   }
@@ -47,4 +75,5 @@ union uuid_t {
     return (b64[0] > other.b64[0] || (b64[0] == other.b64[0] && b64[1] > other.b64[1]));
   }
 };
+}
 #endif //T_MAN_UUID_H