import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

media/mtransport/databuffer.h

@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+// Original author: ekr@rtfm.com
+
+#ifndef databuffer_h__
+#define databuffer_h__
+#include <algorithm>
+#include <mozilla/UniquePtr.h>
+#include <m_cpp_utils.h>
+#include <nsISupportsImpl.h>
+
+namespace mozilla {
+
+class DataBuffer {
+ public:
+  DataBuffer() : data_(nullptr), len_(0), capacity_(0) {}
+  DataBuffer(const uint8_t *data, size_t len) {
+    Assign(data, len, len);
+  }
+  DataBuffer(const uint8_t *data, size_t len, size_t capacity) {
+    Assign(data, len, capacity);
+  }
+
+  // to ensure extra space for expansion
+  void Assign(const uint8_t *data, size_t len, size_t capacity) {
+    MOZ_RELEASE_ASSERT(len <= capacity);
+    Allocate(capacity); // sets len_ = capacity
+    memcpy(static_cast<void *>(data_.get()),
+           static_cast<const void *>(data), len);
+    len_ = len;
+  }
+
+  void Allocate(size_t capacity) {
+    data_.reset(new uint8_t[capacity ? capacity : 1]);  // Don't depend on new [0].
+    len_ = capacity_ = capacity;
+  }
+
+  void EnsureCapacity(size_t capacity) {
+    if (capacity_ < capacity) {
+      uint8_t *new_data = new uint8_t[ capacity ? capacity : 1];
+      memcpy(static_cast<void *>(new_data),
+             static_cast<const void *>(data_.get()), len_);
+      data_.reset(new_data); // after copying!  Deletes old data
+      capacity_ = capacity;
+    }
+  }
+
+  // used when something writes to the buffer (having checked
+  // capacity() or used EnsureCapacity()) and increased the length.
+  void SetLength(size_t len) {
+    MOZ_RELEASE_ASSERT(len <= capacity_);
+    len_ = len;
+  }
+
+  const uint8_t *data() const { return data_.get(); }
+  uint8_t *data() { return data_.get(); }
+  size_t len() const { return len_; }
+  size_t capacity() const { return capacity_; }
+
+private:
+  UniquePtr<uint8_t[]> data_;
+  size_t len_;
+  size_t capacity_;
+
+  DISALLOW_COPY_ASSIGN(DataBuffer);
+};
+
+}
+
+#endif