/*
** Release any memory held by the Mem. This may leave the Mem in an
** inconsistent state, for example with (Mem.z==0) and
** (Mem.type==SQLITE_TEXT).
*/
void sqlite3VdbeMemRelease(Mem *p){
sqlite3VdbeMemReleaseExternal(p);
sqlite3DbFree(p->db, p->zMalloc);
p->z = 0;
p->zMalloc = 0;
p->xDel = 0;
}
/*
** Make an shallow copy of pFrom into pTo. Prior contents of
** pTo are freed. The pFrom->z field is not duplicated. If
** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
** and flags gets srcType (either MEM_Ephem or MEM_Static).
*/
void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
sqlite3VdbeMemReleaseExternal(pTo);
memcpy(pTo, pFrom, MEMCELLSIZE);
pTo->xDel = 0;
if( (pFrom->flags&MEM_Dyn)!=0 || pFrom->z==pFrom->zMalloc ){
pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
assert( srcType==MEM_Ephem || srcType==MEM_Static );
pTo->flags |= srcType;
}
}
/*
** Make a full copy of pFrom into pTo. Prior contents of pTo are
** freed before the copy is made.
*/
int sqlite3VdbeMemCopy(Mem *pTo, const Mem *pFrom){
int rc = SQLITE_OK;
sqlite3VdbeMemReleaseExternal(pTo);
memcpy(pTo, pFrom, MEMCELLSIZE);
pTo->flags &= ~MEM_Dyn;
if( pTo->flags&(MEM_Str|MEM_Blob) ){
if( 0==(pFrom->flags&MEM_Static) ){
pTo->flags |= MEM_Ephem;
rc = sqlite3VdbeMemMakeWriteable(pTo);
}
}
return rc;
}
/*
** Allocate or return the aggregate context for a user function. A new
** context is allocated on the first call. Subsequent calls return the
** same context that was returned on prior calls.
*/
void *sqlite3_aggregate_context(sqlite3_context *p, int nByte){
Mem *pMem;
assert( p && p->pFunc && p->pFunc->xStep );
assert( sqlite3_mutex_held(p->s.db->mutex) );
pMem = p->pMem;
if( (pMem->flags & MEM_Agg)==0 ){
if( nByte==0 ){
sqlite3VdbeMemReleaseExternal(pMem);
pMem->flags = MEM_Null;
pMem->z = 0;
}else{
sqlite3VdbeMemGrow(pMem, nByte, 0);
pMem->flags = MEM_Agg;
pMem->u.pDef = p->pFunc;
if( pMem->z ){
memset(pMem->z, 0, nByte);
}
}
}
return (void*)pMem->z;
}