/*

** 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.

*/

#include "sqliteInt.h"

/*

** Invoke the 'collation needed' callback to request a collation sequence

** in the encoding enc of name zName, length nName.

*/

static void callCollNeeded(sqlite3 *db, int enc, const char *zName){

assert( !db->xCollNeeded || !db->xCollNeeded16 );

if( db->xCollNeeded ){

char *zExternal = sqlite3DbStrDup(db, zName);

if( !zExternal ) return;

db->xCollNeeded(db->pCollNeededArg, db, enc, zExternal);

sqlite3DbFree(db, zExternal);

}

#ifndef SQLITE_OMIT_UTF16

if( db->xCollNeeded16 ){

char const *zExternal;

sqlite3_value *pTmp = sqlite3ValueNew(db);

sqlite3ValueSetStr(pTmp, -1, zName, SQLITE_UTF8, SQLITE_STATIC);

zExternal = sqlite3ValueText(pTmp, SQLITE_UTF16NATIVE);

if( zExternal ){

db->xCollNeeded16(db->pCollNeededArg, db, (int)ENC(db), zExternal);

}

sqlite3ValueFree(pTmp);

}

#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 i;

static const u8 aEnc[] = { SQLITE_UTF16BE, SQLITE_UTF16LE, SQLITE_UTF8 };

for(i=0; i<3; i++){

pColl2 = sqlite3FindCollSeq(db, aEnc[i], z, 0);

if( pColl2->xCmp!=0 ){

memcpy(pColl, pColl2, sizeof(CollSeq));

pColl->xDel = 0; /* Do not copy the destructor */

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 desired 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.

**

** See also: sqlite3LocateCollSeq(), sqlite3FindCollSeq()

*/

CollSeq *sqlite3GetCollSeq(

sqlite3* db, /* The database connection */

u8 enc, /* The desired encoding for the collating sequence */

CollSeq *pColl, /* Collating sequence with native encoding, or NULL */

const char *zName /* Collating sequence name */

){

CollSeq *p;

p = pColl;

if( !p ){

p = sqlite3FindCollSeq(db, enc, zName, 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, enc, zName);

p = sqlite3FindCollSeq(db, enc, zName, 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;

sqlite3 *db = pParse->db;

CollSeq *p = sqlite3GetCollSeq(db, ENC(db), pColl, zName);

if( !p ){

sqlite3ErrorMsg(pParse, "no such collation sequence: %s", zName);

pParse->nErr++;

return SQLITE_ERROR;

}

assert( p==pColl );

}

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, /* Database connection */

const char *zName, /* Name of the collating sequence */

int create /* Create a new entry if true */

){

CollSeq *pColl;

int nName = sqlite3Strlen30(zName);

pColl = sqlite3HashFind(&db->aCollSeq, zName, nName);

if( 0==pColl && create ){

pColl = sqlite3DbMallocZero(db, 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 occurred in sqlite3HashInsert(), it will

** return the pColl pointer to be deleted (because it wasn't added

** to the hash table).

*/

assert( pDel==0 || pDel==pColl );

if( pDel!=0 ){

db->mallocFailed = 1;

sqlite3DbFree(db, pDel);

pColl = 0;

}

}

}

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.

**

** A separate function sqlite3LocateCollSeq() is a wrapper around

** this routine. sqlite3LocateCollSeq() invokes the collation factory

** if necessary and generates an error message if the collating sequence

** cannot be found.

**

** See also: sqlite3LocateCollSeq(), sqlite3GetCollSeq()

*/

CollSeq *sqlite3FindCollSeq(

sqlite3 *db,

u8 enc,

const char *zName,

int create

){

CollSeq *pColl;

if( zName ){

pColl = findCollSeqEntry(db, zName, create);

}else{

pColl = db->pDfltColl;

}

assert( SQLITE_UTF8==1 && SQLITE_UTF16LE==2 && SQLITE_UTF16BE==3 );

assert( enc>=SQLITE_UTF8 && enc<=SQLITE_UTF16BE );

if( pColl ) pColl += enc-1;

return pColl;

}

/* During the search for the best function definition, this procedure

** is called to test how well the function passed as the first argument

** matches the request for a function with nArg arguments in a system

** that uses encoding enc. The value returned indicates how well the

** request is matched. A higher value indicates a better match.

**

** If nArg is -1 that means to only return a match (non-zero) if p->nArg

** is also -1. In other words, we are searching for a function that

** takes a variable number of arguments.

**

** If nArg is -2 that means that we are searching for any function

** regardless of the number of arguments it uses, so return a positive

** match score for any

**

** The returned value is always between 0 and 6, as follows:

**

** 0: Not a match.

** 1: UTF8/16 conversion required and function takes any number of arguments.

** 2: UTF16 byte order change required and function takes any number of args.

** 3: encoding matches and function takes any number of arguments

** 4: UTF8/16 conversion required - argument count matches exactly

** 5: UTF16 byte order conversion required - argument count matches exactly

** 6: Perfect match: encoding and argument count match exactly.

**

** If nArg==(-2) then any function with a non-null xStep or xFunc is

** a perfect match and any function with both xStep and xFunc NULL is

** a non-match.

*/

#define FUNC_PERFECT_MATCH 6 /* The score for a perfect match */

static int matchQuality(

FuncDef *p, /* The function we are evaluating for match quality */

int nArg, /* Desired number of arguments. (-1)==any */

u8 enc /* Desired text encoding */

){

int match;

/* nArg of -2 is a special case */

if( nArg==(-2) ) return (p->xFunc==0 && p->xStep==0) ? 0 : FUNC_PERFECT_MATCH;

/* Wrong number of arguments means "no match" */

if( p->nArg!=nArg && p->nArg>=0 ) return 0;

/* Give a better score to a function with a specific number of arguments

** than to function that accepts any number of arguments. */

if( p->nArg==nArg ){

match = 4;

}else{

match = 1;

}

/* Bonus points if the text encoding matches */

if( enc==p->iPrefEnc ){

match += 2; /* Exact encoding match */

}else if( (enc & p->iPrefEnc & 2)!=0 ){

match += 1; /* Both are UTF16, but with different byte orders */

}

return match;

}

/*

** Search a FuncDefHash for a function with the given name. Return

** a pointer to the matching FuncDef if found, or 0 if there is no match.

*/

static FuncDef *functionSearch(

FuncDefHash *pHash, /* Hash table to search */

int h, /* Hash of the name */

const char *zFunc, /* Name of function */

int nFunc /* Number of bytes in zFunc */

){

FuncDef *p;

for(p=pHash->a[h]; p; p=p->pHash){

if( sqlite3StrNICmp(p->zName, zFunc, nFunc)==0 && p->zName[nFunc]==0 ){

return p;

}

}

return 0;

}

/*

** Insert a new FuncDef into a FuncDefHash hash table.

*/

void sqlite3FuncDefInsert(

FuncDefHash *pHash, /* The hash table into which to insert */

FuncDef *pDef /* The function definition to insert */

){

FuncDef *pOther;

int nName = sqlite3Strlen30(pDef->zName);

u8 c1 = (u8)pDef->zName[0];

int h = (sqlite3UpperToLower[c1] + nName) % ArraySize(pHash->a);

pOther = functionSearch(pHash, h, pDef->zName, nName);

if( pOther ){

assert( pOther!=pDef && pOther->pNext!=pDef );

pDef->pNext = pOther->pNext;

pOther->pNext = pDef;

}else{

pDef->pNext = 0;

pDef->pHash = pHash->a[h];

pHash->a[h] = pDef;

}

}

/*

** 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.

**

** If nArg is -2, then the first valid function found is returned. A

** function is valid if either xFunc or xStep is non-zero. The nArg==(-2)

** case is used to see if zName is a valid function name for some number

** of arguments. If nArg is -2, then createFlag must be 0.

**

** 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 */

u8 createFlag /* Create new entry if true and does not otherwise exist */

){

FuncDef *p; /* Iterator variable */

FuncDef *pBest = 0; /* Best match found so far */

int bestScore = 0; /* Score of best match */

int h; /* Hash value */

assert( nArg>=(-2) );

assert( nArg>=(-1) || createFlag==0 );

assert( enc==SQLITE_UTF8 || enc==SQLITE_UTF16LE || enc==SQLITE_UTF16BE );

h = (sqlite3UpperToLower[(u8)zName[0]] + nName) % ArraySize(db->aFunc.a);

/* First search for a match amongst the application-defined functions.

*/

p = functionSearch(&db->aFunc, h, zName, nName);

while( p ){

int score = matchQuality(p, nArg, enc);

if( score>bestScore ){

pBest = p;

bestScore = score;

}

p = p->pNext;

}

/* If no match is found, search the built-in functions.

**

** If the SQLITE_PreferBuiltin flag is set, then search the built-in

** functions even if a prior app-defined function was found. And give

** priority to built-in functions.

**

** Except, if createFlag is true, that means that we are trying to

** install a new function. Whatever FuncDef structure is returned it will

** have fields overwritten with new information appropriate for the

** new function. But the FuncDefs for built-in functions are read-only.

** So we must not search for built-ins when creating a new function.

*/

if( !createFlag && (pBest==0 || (db->flags & SQLITE_PreferBuiltin)!=0) ){

FuncDefHash *pHash = &GLOBAL(FuncDefHash, sqlite3GlobalFunctions);

bestScore = 0;

p = functionSearch(pHash, h, zName, nName);

while( p ){

int score = matchQuality(p, nArg, enc);

if( score>bestScore ){

pBest = p;

bestScore = score;

}

p = p->pNext;

}

}

/* If the createFlag parameter is true and the search 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 && bestScore<FUNC_PERFECT_MATCH &&

(pBest = sqlite3DbMallocZero(db, sizeof(*pBest)+nName+1))!=0 ){

pBest->zName = (char *)&pBest[1];

pBest->nArg = (u16)nArg;

pBest->iPrefEnc = enc;

memcpy(pBest->zName, zName, nName);

pBest->zName[nName] = 0;

sqlite3FuncDefInsert(&db->aFunc, pBest);

}

if( pBest && (pBest->xStep || pBest->xFunc || createFlag) ){

return pBest;

}

return 0;

}

/*

** Free all resources held by the schema structure. The void* argument points

** at a Schema struct. This function does not call sqlite3DbFree(db, ) on the

** pointer itself, it just cleans up subsidiary resources (i.e. the contents

** of the schema hash tables).

**

** The Schema.cache_size variable is not cleared.

*/

void sqlite3SchemaClear(void *p){

Hash temp1;

Hash temp2;

HashElem *pElem;

Schema *pSchema = (Schema *)p;

temp1 = pSchema->tblHash;

temp2 = pSchema->trigHash;

sqlite3HashInit(&pSchema->trigHash);

sqlite3HashClear(&pSchema->idxHash);

for(pElem=sqliteHashFirst(&temp2); pElem; pElem=sqliteHashNext(pElem)){

sqlite3DeleteTrigger(0, (Trigger*)sqliteHashData(pElem));

}

sqlite3HashClear(&temp2);

sqlite3HashInit(&pSchema->tblHash);

for(pElem=sqliteHashFirst(&temp1); pElem; pElem=sqliteHashNext(pElem)){

Table *pTab = sqliteHashData(pElem);

sqlite3DeleteTable(0, pTab);

}

sqlite3HashClear(&temp1);

sqlite3HashClear(&pSchema->fkeyHash);

pSchema->pSeqTab = 0;

if( pSchema->flags & DB_SchemaLoaded ){

pSchema->iGeneration++;

pSchema->flags &= ~DB_SchemaLoaded;

}

}

/*

** Find and return the schema associated with a BTree. Create

** a new one if necessary.

*/

Schema *sqlite3SchemaGet(sqlite3 *db, Btree *pBt){

Schema * p;

if( pBt ){

p = (Schema *)sqlite3BtreeSchema(pBt, sizeof(Schema), sqlite3SchemaClear);

}else{

p = (Schema *)sqlite3DbMallocZero(0, sizeof(Schema));

}

if( !p ){

db->mallocFailed = 1;

}else if ( 0==p->file_format ){

sqlite3HashInit(&p->tblHash);

sqlite3HashInit(&p->idxHash);

sqlite3HashInit(&p->trigHash);

sqlite3HashInit(&p->fkeyHash);

p->enc = SQLITE_UTF8;

}

return p;

}