src/google/protobuf/repeated_ptr_field.cc

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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// modification, are permitted provided that the following conditions are
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//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
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// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
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// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
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// Author: kenton@google.com (Kenton Varda)
//  Based on original Protocol Buffers design by
//  Sanjay Ghemawat, Jeff Dean, and others.

#include <algorithm>

#include <google/protobuf/stubs/logging.h>
#include <google/protobuf/stubs/common.h>
#include <google/protobuf/implicit_weak_message.h>
#include <google/protobuf/repeated_field.h>
#include <google/protobuf/port.h>

// Must be included last.
#include <google/protobuf/port_def.inc>

namespace google {
namespace protobuf {

namespace internal {

void** RepeatedPtrFieldBase::InternalExtend(int extend_amount) {
  int new_size = current_size_ + extend_amount;
  if (total_size_ >= new_size) {
    // N.B.: rep_ is non-nullptr because extend_amount is always > 0, hence
    // total_size must be non-zero since it is lower-bounded by new_size.
    return &rep_->elements[current_size_];
  }
  Rep* old_rep = rep_;
  Arena* arena = GetOwningArena();
  new_size = internal::CalculateReserveSize<void*, kRepHeaderSize>(total_size_,
                                                                   new_size);
  GOOGLE_CHECK_LE(static_cast<int64_t>(new_size),
           static_cast<int64_t>(
               (std::numeric_limits<size_t>::max() - kRepHeaderSize) /
               sizeof(old_rep->elements[0])))
      << "Requested size is too large to fit into size_t.";
  size_t bytes = kRepHeaderSize + sizeof(old_rep->elements[0]) * new_size;
  if (arena == nullptr) {
    rep_ = reinterpret_cast<Rep*>(::operator new(bytes));
  } else {
    rep_ = reinterpret_cast<Rep*>(Arena::CreateArray<char>(arena, bytes));
  }
  const int old_total_size = total_size_;
  total_size_ = new_size;
  if (old_rep) {
    if (old_rep->allocated_size > 0) {
      memcpy(rep_->elements, old_rep->elements,
             old_rep->allocated_size * sizeof(rep_->elements[0]));
    }
    rep_->allocated_size = old_rep->allocated_size;

    const size_t old_size =
        old_total_size * sizeof(rep_->elements[0]) + kRepHeaderSize;
    if (arena == nullptr) {
      internal::SizedDelete(old_rep, old_size);
    } else {
      arena_->ReturnArrayMemory(old_rep, old_size);
    }
  } else {
    rep_->allocated_size = 0;
  }
  return &rep_->elements[current_size_];
}

void RepeatedPtrFieldBase::Reserve(int new_size) {
  if (new_size > current_size_) {
    InternalExtend(new_size - current_size_);
  }
}

void RepeatedPtrFieldBase::DestroyProtos() {
  GOOGLE_DCHECK(rep_);
  GOOGLE_DCHECK(arena_ == nullptr);
  int n = rep_->allocated_size;
  void* const* elements = rep_->elements;
  for (int i = 0; i < n; i++) {
    delete static_cast<MessageLite*>(elements[i]);
  }
  const size_t size = total_size_ * sizeof(elements[0]) + kRepHeaderSize;
  internal::SizedDelete(rep_, size);
  rep_ = nullptr;
}

void* RepeatedPtrFieldBase::AddOutOfLineHelper(void* obj) {
  if (!rep_ || rep_->allocated_size == total_size_) {
    InternalExtend(1);  // Equivalent to "Reserve(total_size_ + 1)"
  }
  ++rep_->allocated_size;
  rep_->elements[current_size_++] = obj;
  return obj;
}

void RepeatedPtrFieldBase::CloseGap(int start, int num) {
  if (rep_ == nullptr) return;
  // Close up a gap of "num" elements starting at offset "start".
  for (int i = start + num; i < rep_->allocated_size; ++i)
    rep_->elements[i - num] = rep_->elements[i];
  current_size_ -= num;
  rep_->allocated_size -= num;
}

MessageLite* RepeatedPtrFieldBase::AddWeak(const MessageLite* prototype) {
  if (rep_ != nullptr && current_size_ < rep_->allocated_size) {
    return reinterpret_cast<MessageLite*>(rep_->elements[current_size_++]);
  }
  if (!rep_ || rep_->allocated_size == total_size_) {
    Reserve(total_size_ + 1);
  }
  ++rep_->allocated_size;
  MessageLite* result = prototype
                            ? prototype->New(arena_)
                            : Arena::CreateMessage<ImplicitWeakMessage>(arena_);
  rep_->elements[current_size_++] = result;
  return result;
}

}  // namespace internal

}  // namespace protobuf
}  // namespace google

#include <google/protobuf/port_undef.inc>