/*

** 2007 June 22

**

** 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 is part of an SQLite module implementing full-text search.

** This particular file implements the generic tokenizer interface.

*/

/*

** The code in this file is only compiled if:

**

**     * The FTS3 module is being built as an extension

**       (in which case SQLITE_CORE is not defined), or

**

**     * The FTS3 module is being built into the core of

**       SQLite (in which case SQLITE_ENABLE_FTS3 is defined).

*/

#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)

#include "sqlite3ext.h"

#ifndef SQLITE_CORE

  SQLITE_EXTENSION_INIT1

#endif

#include "fts3_hash.h"

#include "fts3_tokenizer.h"

#include <assert.h>

/*

** Implementation of the SQL scalar function for accessing the underlying 

** hash table. This function may be called as follows:

**

**   SELECT <function-name>(<key-name>);

**   SELECT <function-name>(<key-name>, <pointer>);

**

** where <function-name> is the name passed as the second argument

** to the sqlite3Fts3InitHashTable() function (e.g. 'fts3_tokenizer').

**

** If the <pointer> argument is specified, it must be a blob value

** containing a pointer to be stored as the hash data corresponding

** to the string <key-name>. If <pointer> is not specified, then

** the string <key-name> must already exist in the has table. Otherwise,

** an error is returned.

**

** Whether or not the <pointer> argument is specified, the value returned

** is a blob containing the pointer stored as the hash data corresponding

** to string <key-name> (after the hash-table is updated, if applicable).

*/

static void scalarFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  fts3Hash *pHash;

  void *pPtr = 0;

  const unsigned char *zName;

  int nName;

  assert( argc==1 || argc==2 );

  pHash = (fts3Hash *)sqlite3_user_data(context);

  zName = sqlite3_value_text(argv[0]);

  nName = sqlite3_value_bytes(argv[0])+1;

  if( argc==2 ){

    void *pOld;

    int n = sqlite3_value_bytes(argv[1]);

    if( n!=sizeof(pPtr) ){

      sqlite3_result_error(context, "argument type mismatch", -1);

      return;

    }

    pPtr = *(void **)sqlite3_value_blob(argv[1]);

    pOld = sqlite3Fts3HashInsert(pHash, (void *)zName, nName, pPtr);

    if( pOld==pPtr ){

      sqlite3_result_error(context, "out of memory", -1);

      return;

    }

  }else{

    pPtr = sqlite3Fts3HashFind(pHash, zName, nName);

    if( !pPtr ){

      char *zErr = sqlite3_mprintf("unknown tokenizer: %s", zName);

      sqlite3_result_error(context, zErr, -1);

      sqlite3_free(zErr);

      return;

    }

  }

  sqlite3_result_blob(context, (void *)&pPtr, sizeof(pPtr), SQLITE_TRANSIENT);

}

#ifdef SQLITE_TEST

#include "tcl.h"

#include <string.h>

/*

** Implementation of a special SQL scalar function for testing tokenizers 

** designed to be used in concert with the Tcl testing framework. This

** function must be called with two arguments:

**

**   SELECT <function-name>(<key-name>, <input-string>);

**   SELECT <function-name>(<key-name>, <pointer>);

**

** where <function-name> is the name passed as the second argument

** to the sqlite3Fts3InitHashTable() function (e.g. 'fts3_tokenizer')

** concatenated with the string '_test' (e.g. 'fts3_tokenizer_test').

**

** The return value is a string that may be interpreted as a Tcl

** list. For each token in the <input-string>, three elements are

** added to the returned list. The first is the token position, the 

** second is the token text (folded, stemmed, etc.) and the third is the

** substring of <input-string> associated with the token. For example, 

** using the built-in "simple" tokenizer:

**

**   SELECT fts_tokenizer_test('simple', 'I don't see how');

**

** will return the string:

**

**   "{0 i I 1 dont don't 2 see see 3 how how}"

**   

*/

static void testFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  fts3Hash *pHash;

  sqlite3_tokenizer_module *p;

  sqlite3_tokenizer *pTokenizer = 0;

  sqlite3_tokenizer_cursor *pCsr = 0;

  const char *zErr = 0;

  const char *zName;

  int nName;

  const char *zInput;

  int nInput;

  const char *zArg = 0;

  const char *zToken;

  int nToken;

  int iStart;

  int iEnd;

  int iPos;

  Tcl_Obj *pRet;

  assert( argc==2 || argc==3 );

  nName = sqlite3_value_bytes(argv[0]);

  zName = (const char *)sqlite3_value_text(argv[0]);

  nInput = sqlite3_value_bytes(argv[argc-1]);

  zInput = (const char *)sqlite3_value_text(argv[argc-1]);

  if( argc==3 ){

    zArg = (const char *)sqlite3_value_text(argv[1]);

  }

  pHash = (fts3Hash *)sqlite3_user_data(context);

  p = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash, zName, nName+1);

  if( !p ){

    char *zErr = sqlite3_mprintf("unknown tokenizer: %s", zName);

    sqlite3_result_error(context, zErr, -1);

    sqlite3_free(zErr);

    return;

  }

  pRet = Tcl_NewObj();

  Tcl_IncrRefCount(pRet);

  if( SQLITE_OK!=p->xCreate(zArg ? 1 : 0, &zArg, &pTokenizer) ){

    zErr = "error in xCreate()";

    goto finish;

  }

  pTokenizer->pModule = p;

  if( SQLITE_OK!=p->xOpen(pTokenizer, zInput, nInput, &pCsr) ){

    zErr = "error in xOpen()";

    goto finish;

  }

  pCsr->pTokenizer = pTokenizer;

  while( SQLITE_OK==p->xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos) ){

    Tcl_ListObjAppendElement(0, pRet, Tcl_NewIntObj(iPos));

    Tcl_ListObjAppendElement(0, pRet, Tcl_NewStringObj(zToken, nToken));

    zToken = &zInput[iStart];

    nToken = iEnd-iStart;

    Tcl_ListObjAppendElement(0, pRet, Tcl_NewStringObj(zToken, nToken));

  }

  if( SQLITE_OK!=p->xClose(pCsr) ){

    zErr = "error in xClose()";

    goto finish;

  }

  if( SQLITE_OK!=p->xDestroy(pTokenizer) ){

    zErr = "error in xDestroy()";

    goto finish;

  }

finish:

  if( zErr ){

    sqlite3_result_error(context, zErr, -1);

  }else{

    sqlite3_result_text(context, Tcl_GetString(pRet), -1, SQLITE_TRANSIENT);

  }

  Tcl_DecrRefCount(pRet);

}

static

int registerTokenizer(

  sqlite3 *db, 

  char *zName, 

  const sqlite3_tokenizer_module *p

){

  int rc;

  sqlite3_stmt *pStmt;

  const char zSql[] = "SELECT fts3_tokenizer(?, ?)";

  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);

  if( rc!=SQLITE_OK ){

    return rc;

  }

  sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);

  sqlite3_bind_blob(pStmt, 2, &p, sizeof(p), SQLITE_STATIC);

  sqlite3_step(pStmt);

  return sqlite3_finalize(pStmt);

}

static

int queryTokenizer(

  sqlite3 *db, 

  char *zName,  

  const sqlite3_tokenizer_module **pp

){

  int rc;

  sqlite3_stmt *pStmt;

  const char zSql[] = "SELECT fts3_tokenizer(?)";

  *pp = 0;

  rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);

  if( rc!=SQLITE_OK ){

    return rc;

  }

  sqlite3_bind_text(pStmt, 1, zName, -1, SQLITE_STATIC);

  if( SQLITE_ROW==sqlite3_step(pStmt) ){

    if( sqlite3_column_type(pStmt, 0)==SQLITE_BLOB ){

      memcpy(pp, sqlite3_column_blob(pStmt, 0), sizeof(*pp));

    }

  }

  return sqlite3_finalize(pStmt);

}

void sqlite3Fts3SimpleTokenizerModule(sqlite3_tokenizer_module const**ppModule);

/*

** Implementation of the scalar function fts3_tokenizer_internal_test().

** This function is used for testing only, it is not included in the

** build unless SQLITE_TEST is defined.

**

** The purpose of this is to test that the fts3_tokenizer() function

** can be used as designed by the C-code in the queryTokenizer and

** registerTokenizer() functions above. These two functions are repeated

** in the README.tokenizer file as an example, so it is important to

** test them.

**

** To run the tests, evaluate the fts3_tokenizer_internal_test() scalar

** function with no arguments. An assert() will fail if a problem is

** detected. i.e.:

**

**     SELECT fts3_tokenizer_internal_test();

**

*/

static void intTestFunc(

  sqlite3_context *context,

  int argc,

  sqlite3_value **argv

){

  int rc;

  const sqlite3_tokenizer_module *p1;

  const sqlite3_tokenizer_module *p2;

  sqlite3 *db = (sqlite3 *)sqlite3_user_data(context);

  /* Test the query function */

  sqlite3Fts3SimpleTokenizerModule(&p1);

  rc = queryTokenizer(db, "simple", &p2);

  assert( rc==SQLITE_OK );

  assert( p1==p2 );

  rc = queryTokenizer(db, "nosuchtokenizer", &p2);

  assert( rc==SQLITE_ERROR );

  assert( p2==0 );

  assert( 0==strcmp(sqlite3_errmsg(db), "unknown tokenizer: nosuchtokenizer") );

  /* Test the storage function */

  rc = registerTokenizer(db, "nosuchtokenizer", p1);

  assert( rc==SQLITE_OK );

  rc = queryTokenizer(db, "nosuchtokenizer", &p2);

  assert( rc==SQLITE_OK );

  assert( p2==p1 );

  sqlite3_result_text(context, "ok", -1, SQLITE_STATIC);

}

#endif

/*

** Set up SQL objects in database db used to access the contents of

** the hash table pointed to by argument pHash. The hash table must

** been initialised to use string keys, and to take a private copy 

** of the key when a value is inserted. i.e. by a call similar to:

**

**    sqlite3Fts3HashInit(pHash, FTS3_HASH_STRING, 1);

**

** This function adds a scalar function (see header comment above

** scalarFunc() in this file for details) and, if ENABLE_TABLE is

** defined at compilation time, a temporary virtual table (see header 

** comment above struct HashTableVtab) to the database schema. Both 

** provide read/write access to the contents of *pHash.

**

** The third argument to this function, zName, is used as the name

** of both the scalar and, if created, the virtual table.

*/

int sqlite3Fts3InitHashTable(

  sqlite3 *db, 

  fts3Hash *pHash, 

  const char *zName

){

  int rc = SQLITE_OK;

  void *p = (void *)pHash;

  const int any = SQLITE_ANY;

  char *zTest = 0;

  char *zTest2 = 0;

#ifdef SQLITE_TEST

  void *pdb = (void *)db;

  zTest = sqlite3_mprintf("%s_test", zName);

  zTest2 = sqlite3_mprintf("%s_internal_test", zName);

  if( !zTest || !zTest2 ){

    rc = SQLITE_NOMEM;

  }

#endif

  if( rc!=SQLITE_OK

   || (rc = sqlite3_create_function(db, zName, 1, any, p, scalarFunc, 0, 0))

   || (rc = sqlite3_create_function(db, zName, 2, any, p, scalarFunc, 0, 0))

#ifdef SQLITE_TEST

   || (rc = sqlite3_create_function(db, zTest, 2, any, p, testFunc, 0, 0))

   || (rc = sqlite3_create_function(db, zTest, 3, any, p, testFunc, 0, 0))

   || (rc = sqlite3_create_function(db, zTest2, 0, any, pdb, intTestFunc, 0, 0))

#endif

  );

  sqlite3_free(zTest);

  sqlite3_free(zTest2);

  return rc;

}

#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */