1// Copyright (c) 2009 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_SYNC_UTIL_DBGQ_H_
6#define CHROME_BROWSER_SYNC_UTIL_DBGQ_H_
7#pragma once
8
9#include "base/basictypes.h"  // for COMPILE_ASSERT
10
11// A circular queue that is designed to be easily inspectable in a debugger. It
12// puts the elements into the array in reverse, so you can just look at the i_
13// pointer for a recent history.
14template <typename T, size_t size>
15class DebugQueue {
16  COMPILE_ASSERT(size > 0, DebugQueue_size_must_be_greater_than_zero);
17 public:
18  DebugQueue() : i_(array_) { }
19  void Push(const T& t) {
20    i_ = (array_ == i_ ? array_ + size - 1 : i_ - 1);
21    *i_ = t;
22  }
23 protected:
24  T* i_;  // Points to the newest element in the queue.
25  T array_[size];
26};
27
28#endif  // CHROME_BROWSER_SYNC_UTIL_DBGQ_H_
29