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nsAutoBuffer.h
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00001 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
00002 /* ***** BEGIN LICENSE BLOCK *****
00003  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
00004  *
00005  * The contents of this file are subject to the Mozilla Public License Version
00006  * 1.1 (the "License"); you may not use this file except in compliance with
00007  * the License. You may obtain a copy of the License at
00008  * http://www.mozilla.org/MPL/
00009  *
00010  * Software distributed under the License is distributed on an "AS IS" basis,
00011  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
00012  * for the specific language governing rights and limitations under the
00013  * License.
00014  *
00015  * The Original Code is auto buffer template.
00016  *
00017  * The Initial Developer of the Original Code is
00018  * Conrad Carlen <ccarlen@mac.com>.
00019  * Portions created by the Initial Developer are Copyright (C) 2004
00020  * the Initial Developer. All Rights Reserved.
00021  *
00022  * Contributor(s):
00023  *   Jungshik Shin <jshin@mailaps.org>
00024  *
00025  * Alternatively, the contents of this file may be used under the terms of
00026  * either the GNU General Public License Version 2 or later (the "GPL"), or
00027  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
00028  * in which case the provisions of the GPL or the LGPL are applicable instead
00029  * of those above. If you wish to allow use of your version of this file only
00030  * under the terms of either the GPL or the LGPL, and not to allow others to
00031  * use your version of this file under the terms of the MPL, indicate your
00032  * decision by deleting the provisions above and replace them with the notice
00033  * and other provisions required by the GPL or the LGPL. If you do not delete
00034  * the provisions above, a recipient may use your version of this file under
00035  * the terms of any one of the MPL, the GPL or the LGPL.
00036  *
00037  * ***** END LICENSE BLOCK ***** */
00038 
00039 #ifndef nsAutoBuffer_h__
00040 #define nsAutoBuffer_h__
00041 
00042 #ifndef nsMemory_h__
00043 #include "nsMemory.h"
00044 #endif
00045 
00073 template <class T, PRInt32 sz>
00074 class nsAutoBuffer
00075 {
00076 public:
00077   nsAutoBuffer() :
00078     mBufferPtr(mStackBuffer),
00079     mCurElemCapacity(sz)
00080   {
00081   }
00082 
00083   ~nsAutoBuffer()
00084   {
00085     if (mBufferPtr != mStackBuffer)
00086       nsMemory::Free(mBufferPtr);
00087   }
00088 
00089   PRBool EnsureElemCapacity(PRInt32 inElemCapacity)
00090   {
00091     if (inElemCapacity <= mCurElemCapacity)
00092       return PR_TRUE;
00093     
00094     T* newBuffer;
00095 
00096     if (mBufferPtr != mStackBuffer)
00097       newBuffer = (T*)nsMemory::Realloc((void *)mBufferPtr, inElemCapacity * sizeof(T));
00098     else 
00099       newBuffer = (T*)nsMemory::Alloc(inElemCapacity * sizeof(T));
00100 
00101     if (!newBuffer)
00102       return PR_FALSE;
00103 
00104     if (mBufferPtr != mStackBuffer)
00105       nsMemory::Free(mBufferPtr);
00106 
00107     mBufferPtr = newBuffer; 
00108     mCurElemCapacity = inElemCapacity;
00109     return PR_TRUE;
00110   }
00111 
00112   PRBool AddElemCapacity(PRInt32 inElemCapacity)
00113   {
00114     return EnsureElemCapacity(mCurElemCapacity + inElemCapacity);
00115   }
00116 
00117   T*          get()             const  { return mBufferPtr; }
00118   PRInt32     GetElemCapacity() const  { return mCurElemCapacity;  }
00119 
00120 protected:
00121 
00122   T             *mBufferPtr;
00123   T             mStackBuffer[sz];
00124   PRInt32       mCurElemCapacity;
00125 };
00126 
00127 #endif // nsAutoBuffer_h__