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      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.
     14 template <typename T, size_t size>
     15 class 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