dom/canvas/ParamTraits_STL.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef MOZILLA_PARAMTRAITS_STL_H
   7 #define MOZILLA_PARAMTRAITS_STL_H
   8
   9 #include "ipc/IPCMessageUtils.h"
  10 #include "mozilla/ipc/IPDLParamTraits.h"
  11
  12 #include <memory>
  13
  14 namespace IPC {
  15
  16 template <typename U, size_t N>
  17 struct ParamTraits<std::array<U, N>> final {
  18   using T = std::array<U, N>;
  19
  20   static void Write(MessageWriter* const writer, const T& in) {
  21     for (const auto& v : in) {
  22       WriteParam(writer, v);
  23     }
  24   }
  25
  26   static bool Read(MessageReader* const reader, T* const out) {
  27     for (auto& v : *out) {
  28       if (!ReadParam(reader, &v)) return false;
  29     }
  30     return true;
  31   }
  32 };
  33
  34 // -
  35
  36 template <typename U, size_t N>
  37 struct ParamTraits<U[N]> final {
  38   using T = U[N];
  39   static constexpr size_t kByteSize = sizeof(U) * N;
  40
  41   static_assert(std::is_trivial<U>::value);
  42
  43   static void Write(MessageWriter* const writer, const T& in) {
  44     writer->WriteBytes(in, kByteSize);
  45   }
  46
  47   static bool Read(MessageReader* const reader, T* const out) {
  48     if (!reader->HasBytesAvailable(kByteSize)) {
  49       return false;
  50     }
  51     return reader->ReadBytesInto(*out, kByteSize);
  52   }
  53 };
  54
  55 // -
  56
  57 template <class U>
  58 struct ParamTraits<std::optional<U>> final {
  59   using T = std::optional<U>;
  60
  61   static void Write(MessageWriter* const writer, const T& in) {
  62     WriteParam(writer, bool{in});
  63     if (in) {
  64       WriteParam(writer, *in);
  65     }
  66   }
  67
  68   static bool Read(MessageReader* const reader, T* const out) {
  69     bool isSome;
  70     if (!ReadParam(reader, &isSome)) return false;
  71
  72     if (!isSome) {
  73       out->reset();
  74       return true;
  75     }
  76     out->emplace();
  77     return ReadParam(reader, &**out);
  78   }
  79 };
  80
  81 }  // namespace IPC
  82
  83 #endif