added iOS source code

[wl-app.git] / iOS / Pods / Realm / Realm / ObjectStore / src / util / uuid.cpp

diff --git a/iOS/Pods/Realm/Realm/ObjectStore/src/util/uuid.cpp b/iOS/Pods/Realm/Realm/ObjectStore/src/util/uuid.cpp
new file mode 100644 (file)
index 0000000..0110002
--- /dev/null
+++ b/iOS/Pods/Realm/Realm/ObjectStore/src/util/uuid.cpp
@@ -0,0 +1,80 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2017 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+#include "util/uuid.hpp"
+
+#include <algorithm>
+#include <array>
+#include <functional>
+#include <random>
+#include <stdio.h>
+
+namespace {
+
+// Seed `engine` with as much random state as it requires, based on the approach outlined in P0205R0.
+// <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0205r0.html>
+template <typename T>
+T create_and_seed_engine()
+{
+    constexpr auto bytes_needed = T::state_size * sizeof(typename T::result_type);
+
+    constexpr auto numbers_needed = sizeof(std::random_device::result_type) < sizeof(std::seed_seq::result_type)
+                                    ? (bytes_needed / sizeof(std::random_device::result_type))
+                                    : (bytes_needed / sizeof(std::seed_seq::result_type));
+
+    std::array<std::random_device::result_type, numbers_needed> state;
+    std::random_device rd;
+    std::generate(begin(state), end(state), std::ref(rd));
+    std::seed_seq seeds(begin(state), end(state));
+
+    T engine;
+    engine.seed(seeds);
+    return engine;
+}
+
+} // unnamed namespace
+
+namespace realm {
+namespace util {
+
+std::string uuid_string()
+{
+    static auto engine = create_and_seed_engine<std::mt19937>();
+
+    std::array<uint8_t, 16> uuid_bytes;
+    std::uniform_int_distribution<unsigned int> distribution(0, std::numeric_limits<uint8_t>::max());
+    std::generate(begin(uuid_bytes), end(uuid_bytes), [&] { return distribution(engine); });
+
+    // Version 4 UUID.
+    uuid_bytes[6] = (uuid_bytes[6] & 0x0f) | 0x40;
+    // IETF variant.
+    uuid_bytes[8] = (uuid_bytes[8] & 0x3f) | 0x80;
+
+    std::array<char, 37> uuid_formatted;
+    snprintf(uuid_formatted.data(), uuid_formatted.size(),
+             "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
+             uuid_bytes[0], uuid_bytes[1], uuid_bytes[2], uuid_bytes[3],
+             uuid_bytes[4], uuid_bytes[5], uuid_bytes[6], uuid_bytes[7],
+             uuid_bytes[8], uuid_bytes[9], uuid_bytes[10], uuid_bytes[11],
+             uuid_bytes[12], uuid_bytes[13], uuid_bytes[14], uuid_bytes[15]);
+
+    return std::string(uuid_formatted.data(), uuid_formatted.size() - 1);
+}
+
+} // namespace util
+} // namespace realm