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optimisation in wxString::AllocBeforeWrite() - realloc() used instead malloc() whenever possible

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@4574 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 1999-11-15 16:14:10 +00:00
parent 78ee892753
commit fbf0c83d3c
1 changed files with 34 additions and 5 deletions
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39
src/common/string.cpp
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@ -391,13 +391,35 @@ void wxString::AllocBeforeWrite(size_t nLen)
// must not share string and must have enough space
wxStringData* pData = GetStringData();
if ( pData->IsShared() || (nLen > pData->nAllocLength) ) {
if ( pData->IsShared() || pData->IsEmpty() ) {
// can't work with old buffer, get new one
pData->Unlock();
AllocBuffer(nLen);
}
else {
// update the string length
if ( nLen > pData->nAllocLength ) {
// realloc the buffer instead of calling malloc() again, this is more
// efficient
STATISTICS_ADD(Length, nLen);
nLen += EXTRA_ALLOC;
wxStringData *pDataOld = pData;
pData = (wxStringData*)
realloc(pData, sizeof(wxStringData) + (nLen + 1)*sizeof(wxChar));
if ( !pData ) {
// out of memory
free(pDataOld);
// FIXME we're going to crash...
return;
}
pData->nAllocLength = nLen;
m_pchData = pData->data();
}
// now we have enough space, just update the string length
pData->nDataLength = nLen;
}
@ -429,11 +451,15 @@ void wxString::Alloc(size_t nLen)
else {
nLen += EXTRA_ALLOC;
wxStringData *pDataOld = pData;
wxStringData *p = (wxStringData *)
realloc(pData, sizeof(wxStringData) + (nLen + 1)*sizeof(wxChar));
if ( p == NULL ) {
// @@@ what to do on memory error?
// don't leak memory
free(pDataOld);
// FIXME what to do on memory error?
return;
}
@ -451,13 +477,16 @@ void wxString::Shrink()
{
wxStringData *pData = GetStringData();
// this variable is unused in release build, so avoid the compiler warning by
// just not declaring it
// this variable is unused in release build, so avoid the compiler warning
// by just not declaring it
#ifdef __WXDEBUG__
void *p =
#endif
realloc(pData, sizeof(wxStringData) + (pData->nDataLength + 1)*sizeof(wxChar));
// we rely on a reasonable realloc() implementation here - so far I haven't
// seen any which wouldn't behave like this
wxASSERT( p != NULL ); // can't free memory?
wxASSERT( p == pData ); // we're decrementing the size - block shouldn't move!
}