Move webrtc/{base => rtc_base}

webrtc/base/buffer.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_BASE_BUFFER_H_
 #define WEBRTC_BASE_BUFFER_H_
 
-#include <algorithm>
-#include <cstring>
-#include <memory>
-#include <type_traits>
-#include <utility>
-
-#include "webrtc/base/array_view.h"
-#include "webrtc/base/checks.h"
-#include "webrtc/base/type_traits.h"
-
-namespace rtc {
-
-namespace internal {
-
-// (Internal; please don't use outside this file.) Determines if elements of
-// type U are compatible with a BufferT<T>. For most types, we just ignore
-// top-level const and forbid top-level volatile and require T and U to be
-// otherwise equal, but all byte-sized integers (notably char, int8_t, and
-// uint8_t) are compatible with each other. (Note: We aim to get rid of this
-// behavior, and treat all types the same.)
-template <typename T, typename U>
-struct BufferCompat {
-  static constexpr bool value =
-      !std::is_volatile<U>::value &&
-      ((std::is_integral<T>::value && sizeof(T) == 1)
-           ? (std::is_integral<U>::value && sizeof(U) == 1)
-           : (std::is_same<T, typename std::remove_const<U>::type>::value));
-};
-
-}  // namespace internal
-
-// Basic buffer class, can be grown and shrunk dynamically.
-// Unlike std::string/vector, does not initialize data when increasing size.
-template <typename T>
-class BufferT {
-  // We want T's destructor and default constructor to be trivial, i.e. perform
-  // no action, so that we don't have to touch the memory we allocate and
-  // deallocate. And we want T to be trivially copyable, so that we can copy T
-  // instances with std::memcpy. This is precisely the definition of a trivial
-  // type.
-  static_assert(std::is_trivial<T>::value, "T must be a trivial type.");
-
-  // This class relies heavily on being able to mutate its data.
-  static_assert(!std::is_const<T>::value, "T may not be const");
-
- public:
-  using value_type = T;
-
-  // An empty BufferT.
-  BufferT() : size_(0), capacity_(0), data_(nullptr) {
-    RTC_DCHECK(IsConsistent());
-  }
-
-  // Disable copy construction and copy assignment, since copying a buffer is
-  // expensive enough that we want to force the user to be explicit about it.
-  BufferT(const BufferT&) = delete;
-  BufferT& operator=(const BufferT&) = delete;
-
-  BufferT(BufferT&& buf)
-      : size_(buf.size()),
-        capacity_(buf.capacity()),
-        data_(std::move(buf.data_)) {
-    RTC_DCHECK(IsConsistent());
-    buf.OnMovedFrom();
-  }
-
-  // Construct a buffer with the specified number of uninitialized elements.
-  explicit BufferT(size_t size) : BufferT(size, size) {}
-
-  BufferT(size_t size, size_t capacity)
-      : size_(size),
-        capacity_(std::max(size, capacity)),
-        data_(new T[capacity_]) {
-    RTC_DCHECK(IsConsistent());
-  }
-
-  // Construct a buffer and copy the specified number of elements into it.
-  template <typename U,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  BufferT(const U* data, size_t size) : BufferT(data, size, size) {}
-
-  template <typename U,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  BufferT(U* data, size_t size, size_t capacity) : BufferT(size, capacity) {
-    static_assert(sizeof(T) == sizeof(U), "");
-    std::memcpy(data_.get(), data, size * sizeof(U));
-  }
-
-  // Construct a buffer from the contents of an array.
-  template <typename U,
-            size_t N,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  BufferT(U (&array)[N]) : BufferT(array, N) {}
-
-  // Get a pointer to the data. Just .data() will give you a (const) T*, but if
-  // T is a byte-sized integer, you may also use .data<U>() for any other
-  // byte-sized integer U.
-  template <typename U = T,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  const U* data() const {
-    RTC_DCHECK(IsConsistent());
-    return reinterpret_cast<U*>(data_.get());
-  }
-
-  template <typename U = T,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  U* data() {
-    RTC_DCHECK(IsConsistent());
-    return reinterpret_cast<U*>(data_.get());
-  }
-
-  bool empty() const {
-    RTC_DCHECK(IsConsistent());
-    return size_ == 0;
-  }
-
-  size_t size() const {
-    RTC_DCHECK(IsConsistent());
-    return size_;
-  }
-
-  size_t capacity() const {
-    RTC_DCHECK(IsConsistent());
-    return capacity_;
-  }
-
-  BufferT& operator=(BufferT&& buf) {
-    RTC_DCHECK(IsConsistent());
-    RTC_DCHECK(buf.IsConsistent());
-    size_ = buf.size_;
-    capacity_ = buf.capacity_;
-    data_ = std::move(buf.data_);
-    buf.OnMovedFrom();
-    return *this;
-  }
-
-  bool operator==(const BufferT& buf) const {
-    RTC_DCHECK(IsConsistent());
-    if (size_ != buf.size_) {
-      return false;
-    }
-    if (std::is_integral<T>::value) {
-      // Optimization.
-      return std::memcmp(data_.get(), buf.data_.get(), size_ * sizeof(T)) == 0;
-    }
-    for (size_t i = 0; i < size_; ++i) {
-      if (data_[i] != buf.data_[i]) {
-        return false;
-      }
-    }
-    return true;
-  }
-
-  bool operator!=(const BufferT& buf) const { return !(*this == buf); }
-
-  T& operator[](size_t index) {
-    RTC_DCHECK_LT(index, size_);
-    return data()[index];
-  }
-
-  T operator[](size_t index) const {
-    RTC_DCHECK_LT(index, size_);
-    return data()[index];
-  }
-
-  T* begin() { return data(); }
-  T* end() { return data() + size(); }
-  const T* begin() const { return data(); }
-  const T* end() const { return data() + size(); }
-  const T* cbegin() const { return data(); }
-  const T* cend() const { return data() + size(); }
-
-  // The SetData functions replace the contents of the buffer. They accept the
-  // same input types as the constructors.
-  template <typename U,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  void SetData(const U* data, size_t size) {
-    RTC_DCHECK(IsConsistent());
-    size_ = 0;
-    AppendData(data, size);
-  }
-
-  template <typename U,
-            size_t N,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  void SetData(const U (&array)[N]) {
-    SetData(array, N);
-  }
-
-  template <typename W,
-            typename std::enable_if<
-                HasDataAndSize<const W, const T>::value>::type* = nullptr>
-  void SetData(const W& w) {
-    SetData(w.data(), w.size());
-  }
-
-  // Replace the data in the buffer with at most |max_elements| of data, using
-  // the function |setter|, which should have the following signature:
-  //   size_t setter(ArrayView<U> view)
-  // |setter| is given an appropriately typed ArrayView of the area in which to
-  // write the data (i.e. starting at the beginning of the buffer) and should
-  // return the number of elements actually written. This number must be <=
-  // |max_elements|.
-  template <typename U = T,
-            typename F,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  size_t SetData(size_t max_elements, F&& setter) {
-    RTC_DCHECK(IsConsistent());
-    size_ = 0;
-    return AppendData<U>(max_elements, std::forward<F>(setter));
-  }
-
-  // The AppendData functions add data to the end of the buffer. They accept
-  // the same input types as the constructors.
-  template <typename U,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  void AppendData(const U* data, size_t size) {
-    RTC_DCHECK(IsConsistent());
-    const size_t new_size = size_ + size;
-    EnsureCapacityWithHeadroom(new_size, true);
-    static_assert(sizeof(T) == sizeof(U), "");
-    std::memcpy(data_.get() + size_, data, size * sizeof(U));
-    size_ = new_size;
-    RTC_DCHECK(IsConsistent());
-  }
-
-  template <typename U,
-            size_t N,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  void AppendData(const U (&array)[N]) {
-    AppendData(array, N);
-  }
-
-  template <typename W,
-            typename std::enable_if<
-                HasDataAndSize<const W, const T>::value>::type* = nullptr>
-  void AppendData(const W& w) {
-    AppendData(w.data(), w.size());
-  }
-
-  template <typename U,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  void AppendData(const U& item) {
-    AppendData(&item, 1);
-  }
-
-  // Append at most |max_elements| to the end of the buffer, using the function
-  // |setter|, which should have the following signature:
-  //   size_t setter(ArrayView<U> view)
-  // |setter| is given an appropriately typed ArrayView of the area in which to
-  // write the data (i.e. starting at the former end of the buffer) and should
-  // return the number of elements actually written. This number must be <=
-  // |max_elements|.
-  template <typename U = T,
-            typename F,
-            typename std::enable_if<
-                internal::BufferCompat<T, U>::value>::type* = nullptr>
-  size_t AppendData(size_t max_elements, F&& setter) {
-    RTC_DCHECK(IsConsistent());
-    const size_t old_size = size_;
-    SetSize(old_size + max_elements);
-    U* base_ptr = data<U>() + old_size;
-    size_t written_elements = setter(rtc::ArrayView<U>(base_ptr, max_elements));
-
-    RTC_CHECK_LE(written_elements, max_elements);
-    size_ = old_size + written_elements;
-    RTC_DCHECK(IsConsistent());
-    return written_elements;
-  }
-
-  // Sets the size of the buffer. If the new size is smaller than the old, the
-  // buffer contents will be kept but truncated; if the new size is greater,
-  // the existing contents will be kept and the new space will be
-  // uninitialized.
-  void SetSize(size_t size) {
-    EnsureCapacityWithHeadroom(size, true);
-    size_ = size;
-  }
-
-  // Ensure that the buffer size can be increased to at least capacity without
-  // further reallocation. (Of course, this operation might need to reallocate
-  // the buffer.)
-  void EnsureCapacity(size_t capacity) {
-    // Don't allocate extra headroom, since the user is asking for a specific
-    // capacity.
-    EnsureCapacityWithHeadroom(capacity, false);
-  }
-
-  // Resets the buffer to zero size without altering capacity. Works even if the
-  // buffer has been moved from.
-  void Clear() {
-    size_ = 0;
-    RTC_DCHECK(IsConsistent());
-  }
-
-  // Swaps two buffers. Also works for buffers that have been moved from.
-  friend void swap(BufferT& a, BufferT& b) {
-    using std::swap;
-    swap(a.size_, b.size_);
-    swap(a.capacity_, b.capacity_);
-    swap(a.data_, b.data_);
-  }
-
- private:
-  void EnsureCapacityWithHeadroom(size_t capacity, bool extra_headroom) {
-    RTC_DCHECK(IsConsistent());
-    if (capacity <= capacity_)
-      return;
-
-    // If the caller asks for extra headroom, ensure that the new capacity is
-    // >= 1.5 times the old capacity. Any constant > 1 is sufficient to prevent
-    // quadratic behavior; as to why we pick 1.5 in particular, see
-    // https://github.com/facebook/folly/blob/master/folly/docs/FBVector.md and
-    // http://www.gahcep.com/cpp-internals-stl-vector-part-1/.
-    const size_t new_capacity =
-        extra_headroom ? std::max(capacity, capacity_ + capacity_ / 2)
-                       : capacity;
-
-    std::unique_ptr<T[]> new_data(new T[new_capacity]);
-    std::memcpy(new_data.get(), data_.get(), size_ * sizeof(T));
-    data_ = std::move(new_data);
-    capacity_ = new_capacity;
-    RTC_DCHECK(IsConsistent());
-  }
-
-  // Precondition for all methods except Clear and the destructor.
-  // Postcondition for all methods except move construction and move
-  // assignment, which leave the moved-from object in a possibly inconsistent
-  // state.
-  bool IsConsistent() const {
-    return (data_ || capacity_ == 0) && capacity_ >= size_;
-  }
-
-  // Called when *this has been moved from. Conceptually it's a no-op, but we
-  // can mutate the state slightly to help subsequent sanity checks catch bugs.
-  void OnMovedFrom() {
-#if RTC_DCHECK_IS_ON
-    // Make *this consistent and empty. Shouldn't be necessary, but better safe
-    // than sorry.
-    size_ = 0;
-    capacity_ = 0;
-#else
-    // Ensure that *this is always inconsistent, to provoke bugs.
-    size_ = 1;
-    capacity_ = 0;
-#endif
-  }
-
-  size_t size_;
-  size_t capacity_;
-  std::unique_ptr<T[]> data_;
-};
-
-// By far the most common sort of buffer.
-using Buffer = BufferT<uint8_t>;
-
-}  // namespace rtc
+// This header is deprecated and is just left here temporarily during
+// refactoring. See https://bugs.webrtc.org/7634 for more details.
+#include "webrtc/rtc_base/buffer.h"
 
 #endif  // WEBRTC_BASE_BUFFER_H_