/*
** 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;
if( pTo->flags & MEM_Dyn ){
sqlite3VdbeMemRelease(pTo);
}
sqlite3VdbeMemShallowCopy(pTo, pFrom, MEM_Ephem);
if( pTo->flags & MEM_Ephem ){
rc = sqlite3VdbeMemMakeWriteable(pTo);
}else{
rc = SQLITE_OK;
}
return rc;
}
/*
** Compare the values contained by the two memory cells, returning
** negative, zero or positive if pMem1 is less than, equal to, or greater
** than pMem2. Sorting order is NULL's first, followed by numbers (integers
** and reals) sorted numerically, followed by text ordered by the collating
** sequence pColl and finally blob's ordered by memcmp().
**
** Two NULL values are considered equal by this function.
*/
int sqlite3MemCompare(const Mem *pMem1, const Mem *pMem2, const CollSeq *pColl){
int rc;
int f1, f2;
int combined_flags;
/* Interchange pMem1 and pMem2 if the collating sequence specifies
** DESC order.
*/
f1 = pMem1->flags;
f2 = pMem2->flags;
combined_flags = f1|f2;
/* If one value is NULL, it is less than the other. If both values
** are NULL, return 0.
*/
if( combined_flags&MEM_Null ){
return (f2&MEM_Null) - (f1&MEM_Null);
}
/* If one value is a number and the other is not, the number is less.
** If both are numbers, compare as reals if one is a real, or as integers
** if both values are integers.
*/
if( combined_flags&(MEM_Int|MEM_Real) ){
if( !(f1&(MEM_Int|MEM_Real)) ){
return 1;
}
if( !(f2&(MEM_Int|MEM_Real)) ){
return -1;
}
if( (f1 & f2 & MEM_Int)==0 ){
double r1, r2;
if( (f1&MEM_Real)==0 ){
r1 = pMem1->u.i;
}else{
r1 = pMem1->r;
}
if( (f2&MEM_Real)==0 ){
r2 = pMem2->u.i;
}else{
r2 = pMem2->r;
}
if( r1<r2 ) return -1;
if( r1>r2 ) return 1;
return 0;
}else{
assert( f1&MEM_Int );
assert( f2&MEM_Int );
if( pMem1->u.i < pMem2->u.i ) return -1;
if( pMem1->u.i > pMem2->u.i ) return 1;
return 0;
}
}
/* If one value is a string and the other is a blob, the string is less.
** If both are strings, compare using the collating functions.
*/
if( combined_flags&MEM_Str ){
if( (f1 & MEM_Str)==0 ){
return 1;
}
if( (f2 & MEM_Str)==0 ){
return -1;
}
assert( pMem1->enc==pMem2->enc );
assert( pMem1->enc==SQLITE_UTF8 ||
pMem1->enc==SQLITE_UTF16LE || pMem1->enc==SQLITE_UTF16BE );
/* The collation sequence must be defined at this point, even if
** the user deletes the collation sequence after the vdbe program is
** compiled (this was not always the case).
*/
assert( !pColl || pColl->xCmp );
if( pColl ){
if( pMem1->enc==pColl->enc ){
/* The strings are already in the correct encoding. Call the
** comparison function directly */
return pColl->xCmp(pColl->pUser,pMem1->n,pMem1->z,pMem2->n,pMem2->z);
}else{
const void *v1, *v2;
int n1, n2;
Mem c1;
Mem c2;
memset(&c1, 0, sizeof(c1));
memset(&c2, 0, sizeof(c2));
sqlite3VdbeMemShallowCopy(&c1, pMem1, MEM_Ephem);
sqlite3VdbeMemShallowCopy(&c2, pMem2, MEM_Ephem);
v1 = sqlite3ValueText((sqlite3_value*)&c1, pColl->enc);
n1 = v1==0 ? 0 : c1.n;
v2 = sqlite3ValueText((sqlite3_value*)&c2, pColl->enc);
n2 = v2==0 ? 0 : c2.n;
rc = pColl->xCmp(pColl->pUser, n1, v1, n2, v2);
sqlite3VdbeMemRelease(&c1);
sqlite3VdbeMemRelease(&c2);
return rc;
}
}
/* If a NULL pointer was passed as the collate function, fall through
** to the blob case and use memcmp(). */
}
/* Both values must be blobs. Compare using memcmp(). */
rc = memcmp(pMem1->z, pMem2->z, (pMem1->n>pMem2->n)?pMem2->n:pMem1->n);
if( rc==0 ){
rc = pMem1->n - pMem2->n;
}
return rc;
}
