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bug 233485 : add 'size' parameter to nsAutoBuffer (r=ccalren, sr=rbs)

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This commit is contained in:
jshin%mailaps.org 2004-02-19 10:50:20 +00:00
parent 90143bbc67
commit a99b882982
1 changed files with 48 additions and 26 deletions
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74
xpcom/ds/nsAutoBuffer.h
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@ -20,6 +20,7 @@
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Jungshik Shin <jshin@mailaps.org>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
@ -45,21 +46,44 @@
/**
* A buffer which will use stack space if the requested size will
* fit in the stack buffer and allocate from the heap if not.
*
* Below is a usage example :
*
* typedef nsAutoBuffer<PRUnichar, 256> nsAutoUnicharBuffer;
*
* nsAutoUnicharBuffer buffer;
*
* if (!buffer.EnsureElemCapacity(initialLength))
* return NS_ERROR_OUT_OF_MEMORY;
*
* PRUnichar *unicharPtr = buffer.get();
*
* // add PRUnichar's to the buffer pointed to by |unicharPtr| as long as
* // the number of PRUnichar's is less than |intialLength|
*
* // increase the capacity
* if (!buffer.AddElemCapacity(extraLength))
* return NS_ERROR_OUT_OF_MEMORY
*
* unicharPtr = buffer.get() + initialLength;
*
* //continue to add PRUnichar's....
*/
template <class T>
template <class T, PRInt32 sz>
class nsAutoBuffer
{
public:
nsAutoBuffer() :
mBufferPtr(mStackBuffer),
mCurElemCapacity(kStackBufferNumElems)
mCurElemCapacity(sz)
{
}
~nsAutoBuffer()
{
DeleteBuffer();
if (mBufferPtr != mStackBuffer)
nsMemory::Free(mBufferPtr);
}
PRBool EnsureElemCapacity(PRInt32 inElemCapacity)
@ -67,38 +91,36 @@ public:
if (inElemCapacity <= mCurElemCapacity)
return PR_TRUE;
if (inElemCapacity > kStackBufferNumElems)
{
DeleteBuffer();
mBufferPtr = (T*)nsMemory::Alloc(inElemCapacity * sizeof(T));
mCurElemCapacity = inElemCapacity;
return (mBufferPtr != NULL);
}
mCurElemCapacity = kStackBufferNumElems;
T* newBuffer;
if (mBufferPtr != mStackBuffer)
newBuffer = (T*)nsMemory::Realloc((void *)mBufferPtr, inElemCapacity * sizeof(T));
else
newBuffer = (T*)nsMemory::Alloc(inElemCapacity * sizeof(T));
if (!newBuffer)
return PR_FALSE;
if (mBufferPtr != mStackBuffer)
nsMemory::Free(mBufferPtr);
mBufferPtr = newBuffer;
mCurElemCapacity = inElemCapacity;
return PR_TRUE;
}
PRInt32 GetElemCapacity() { return mCurElemCapacity; } const
T* get() { return mBufferPtr; } const
protected:
void DeleteBuffer()
PRBool AddElemCapacity(PRInt32 inElemCapacity)
{
if (mBufferPtr != mStackBuffer)
{
nsMemory::Free(mBufferPtr);
mBufferPtr = mStackBuffer;
}
return EnsureElemCapacity(mCurElemCapacity + inElemCapacity);
}
T* get() const { return mBufferPtr; }
PRInt32 GetElemCapacity() const { return mCurElemCapacity; }
protected:
enum { kStackBufferNumElems = 256 };
T *mBufferPtr;
T mStackBuffer[kStackBufferNumElems];
T mStackBuffer[sz];
PRInt32 mCurElemCapacity;
};