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/*
** 2005 May 23
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains functions used to access the internal hash tables
** of user defined functions and collation sequences.
**
** $Id$
*/
#include "sqliteInt.h"
/*
** Invoke the 'collation needed' callback to request a collation sequence
** in the database text encoding of name zName, length nName.
** If the collation sequence
*/
static void callCollNeeded(sqlite3 *db, const char *zName, int nName){
assert( !db->xCollNeeded || !db->xCollNeeded16 );
if( nName<0 ) nName = strlen(zName);
if( db->xCollNeeded ){
char *zExternal = sqliteStrNDup(zName, nName);
if( !zExternal ) return;
db->xCollNeeded(db->pCollNeededArg, db, (int)db->enc, zExternal);
sqliteFree(zExternal);
}
#ifndef SQLITE_OMIT_UTF16
if( db->xCollNeeded16 ){
char const *zExternal;
sqlite3_value *pTmp = sqlite3GetTransientValue(db);
sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF8, SQLITE_STATIC);
zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);
if( !zExternal ) return;
db->xCollNeeded16(db->pCollNeededArg, db, (int)db->enc, zExternal);
}
#endif
}
/*
** This routine is called if the collation factory fails to deliver a
** collation function in the best encoding but there may be other versions
** of this collation function (for other text encodings) available. Use one
** of these instead if they exist. Avoid a UTF-8 <-> UTF-16 conversion if
** possible.
*/
static int synthCollSeq(sqlite3 *db, CollSeq *pColl){
CollSeq *pColl2;
char *z = pColl->zName;
int n = strlen(z);
int i;
static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };
for(i=0; i<3; i++){
pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, n, 0);
if( pColl2->xCmp!=0 ){
memcpy(pColl, pColl2, sizeof(CollSeq));
return SQLITE_OK;
}
}
return SQLITE_ERROR;
}
/*
** This function is responsible for invoking the collation factory callback
** or substituting a collation sequence of a different encoding when the
** requested collation sequence is not available in the database native
** encoding.
**
** If it is not NULL, then pColl must point to the database native encoding
** collation sequence with name zName, length nName.
**
** The return value is either the collation sequence to be used in database
** db for collation type name zName, length nName, or NULL, if no collation
** sequence can be found.
*/
CollSeq *sqlite3GetCollSeq(
sqlite3* db,
CollSeq *pColl,
const char *zName,
int nName
){
CollSeq *p;
p = pColl;
if( !p ){
p = sqlite3FindCollSeq(db, db->enc, zName, nName, 0);
}
if( !p || !p->xCmp ){
/* No collation sequence of this type for this encoding is registered.
** Call the collation factory to see if it can supply us with one.
*/
callCollNeeded(db, zName, nName);
p = sqlite3FindCollSeq(db, db->enc, zName, nName, 0);
}
if( p && !p->xCmp && synthCollSeq(db, p) ){
p = 0;
}
assert( !p || p->xCmp );
return p;
}
/*
** This routine is called on a collation sequence before it is used to
** check that it is defined. An undefined collation sequence exists when
** a database is loaded that contains references to collation sequences
** that have not been defined by sqlite3_create_collation() etc.
**
** If required, this routine calls the 'collation needed' callback to
** request a definition of the collating sequence. If this doesn't work,
** an equivalent collating sequence that uses a text encoding different
** from the main database is substituted, if one is available.
*/
int sqlite3CheckCollSeq(Parse *pParse, CollSeq *pColl){
if( pColl ){
const char *zName = pColl->zName;
CollSeq *p = sqlite3GetCollSeq(pParse->db, pColl, zName, -1);
if( !p ){
if( pParse->nErr==0 ){
sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);
}
pParse->nErr++;
return SQLITE_ERROR;
}
}
return SQLITE_OK;
}
/*
** Locate and return an entry from the db.aCollSeq hash table. If the entry
** specified by zName and nName is not found and parameter 'create' is
** true, then create a new entry. Otherwise return NULL.
**
** Each pointer stored in the sqlite3.aCollSeq hash table contains an
** array of three CollSeq structures. The first is the collation sequence
** prefferred for UTF-8, the second UTF-16le, and the third UTF-16be.
**
** Stored immediately after the three collation sequences is a copy of
** the collation sequence name. A pointer to this string is stored in
** each collation sequence structure.
*/
static CollSeq * findCollSeqEntry(
sqlite3 *db,
const char *zName,
int nName,
int create
){
CollSeq *pColl;
if( nName<0 ) nName = strlen(zName);
pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);
if( 0==pColl && create ){
pColl = sqliteMalloc( 3*sizeof(*pColl) + nName + 1 );
if( pColl ){
CollSeq *pDel = 0;
pColl[0].zName = (char*)&pColl[3];
pColl[0].enc = SQLITE_UTF8;
pColl[1].zName = (char*)&pColl[3];
pColl[1].enc = SQLITE_UTF16LE;
pColl[2].zName = (char*)&pColl[3];
pColl[2].enc = SQLITE_UTF16BE;
memcpy(pColl[0].zName, zName, nName);
pColl[0].zName[nName] = 0;
pDel = sqlite3HashInsert(&db->aCollSeq, pColl[0].zName, nName, pColl);
/* If a malloc() failure occured in sqlite3HashInsert(), it will
** return the pColl pointer to be deleted (because it wasn't added
** to the hash table).
*/
assert( !pDel || (sqlite3_malloc_failed && pDel==pColl) );
sqliteFree(pDel);
}
}
return pColl;
}
/*
** Parameter zName points to a UTF-8 encoded string nName bytes long.
** Return the CollSeq* pointer for the collation sequence named zName
** for the encoding 'enc' from the database 'db'.
**
** If the entry specified is not found and 'create' is true, then create a
** new entry. Otherwise return NULL.
*/
CollSeq *sqlite3FindCollSeq(
sqlite3 *db,
u8 enc,
const char *zName,
int nName,
int create
){
CollSeq *pColl = findCollSeqEntry(db, zName, nName, create);
assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );
assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );
if( pColl ) pColl += enc-1;
return pColl;
}
/*
** Locate a user function given a name, a number of arguments and a flag
** indicating whether the function prefers UTF-16 over UTF-8. Return a
** pointer to the FuncDef structure that defines that function, or return
** NULL if the function does not exist.
**
** If the createFlag argument is true, then a new (blank) FuncDef
** structure is created and liked into the "db" structure if a
** no matching function previously existed. When createFlag is true
** and the nArg parameter is -1, then only a function that accepts
** any number of arguments will be returned.
**
** If createFlag is false and nArg is -1, then the first valid
** function found is returned. A function is valid if either xFunc
** or xStep is non-zero.
**
** If createFlag is false, then a function with the required name and
** number of arguments may be returned even if the eTextRep flag does not
** match that requested.
*/
FuncDef *sqlite3FindFunction(
sqlite3 *db, /* An open database */
const char *zName, /* Name of the function. Not null-terminated */
int nName, /* Number of characters in the name */
int nArg, /* Number of arguments. -1 means any number */
u8 enc, /* Preferred text encoding */
int createFlag /* Create new entry if true and does not otherwise exist */
){
FuncDef *p; /* Iterator variable */
FuncDef *pFirst; /* First function with this name */
FuncDef *pBest = 0; /* Best match found so far */
int bestmatch = 0;
assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );
if( nArg<-1 ) nArg = -1;
pFirst = (FuncDef*)sqlite3HashFind(&db->aFunc, zName, nName);
for(p=pFirst; p; p=p->pNext){
/* During the search for the best function definition, bestmatch is set
** as follows to indicate the quality of the match with the definition
** pointed to by pBest:
**
** 0: pBest is NULL. No match has been found.
** 1: A variable arguments function that prefers UTF-8 when a UTF-16
** encoding is requested, or vice versa.
** 2: A variable arguments function that uses UTF-16BE when UTF-16LE is
** requested, or vice versa.
** 3: A variable arguments function using the same text encoding.
** 4: A function with the exact number of arguments requested that
** prefers UTF-8 when a UTF-16 encoding is requested, or vice versa.
** 5: A function with the exact number of arguments requested that
** prefers UTF-16LE when UTF-16BE is requested, or vice versa.
** 6: An exact match.
**
** A larger value of 'matchqual' indicates a more desirable match.
*/
if( p->nArg==-1 || p->nArg==nArg || nArg==-1 ){
int match = 1; /* Quality of this match */
if( p->nArg==nArg || nArg==-1 ){
match = 4;
}
if( enc==p->iPrefEnc ){
match += 2;
}
else if( (enc==SQLITE_UTF16LE && p->iPrefEnc==SQLITE_UTF16BE) ||
(enc==SQLITE_UTF16BE && p->iPrefEnc==SQLITE_UTF16LE) ){
match += 1;
}
if( match>bestmatch ){
pBest = p;
bestmatch = match;
}
}
}
/* If the createFlag parameter is true, and the seach did not reveal an
** exact match for the name, number of arguments and encoding, then add a
** new entry to the hash table and return it.
*/
if( createFlag && bestmatch<6 &&
(pBest = sqliteMalloc(sizeof(*pBest)+nName+1)) ){
pBest->nArg = nArg;
pBest->pNext = pFirst;
pBest->zName = (char*)&pBest[1];
pBest->iPrefEnc = enc;
memcpy(pBest->zName, zName, nName);
pBest->zName[nName] = 0;
if( pBest==sqlite3HashInsert(&db->aFunc,pBest->zName,nName,(void*)pBest) ){
sqliteFree(pBest);
return 0;
}
}
if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){
return pBest;
}
return 0;
}