457 lines
13 KiB
C
457 lines
13 KiB
C
/*
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** 2013 Apr 22
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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******************************************************************************
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**
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** This file contains code for the "fts3tokenize" virtual table module.
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** An fts3tokenize virtual table is created as follows:
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**
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** CREATE VIRTUAL TABLE <tbl> USING fts3tokenize(
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** <tokenizer-name>, <arg-1>, ...
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** );
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**
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** The table created has the following schema:
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**
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** CREATE TABLE <tbl>(input, token, start, end, position)
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**
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** When queried, the query must include a WHERE clause of type:
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**
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** input = <string>
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**
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** The virtual table module tokenizes this <string>, using the FTS3
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** tokenizer specified by the arguments to the CREATE VIRTUAL TABLE
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** statement and returns one row for each token in the result. With
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** fields set as follows:
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**
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** input: Always set to a copy of <string>
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** token: A token from the input.
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** start: Byte offset of the token within the input <string>.
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** end: Byte offset of the byte immediately following the end of the
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** token within the input string.
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** pos: Token offset of token within input.
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**
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*/
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#include "fts3Int.h"
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#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
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#include <string.h>
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#include <assert.h>
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typedef struct Fts3tokTable Fts3tokTable;
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typedef struct Fts3tokCursor Fts3tokCursor;
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/*
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** Virtual table structure.
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*/
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struct Fts3tokTable {
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sqlite3_vtab base; /* Base class used by SQLite core */
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const sqlite3_tokenizer_module *pMod;
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sqlite3_tokenizer *pTok;
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};
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/*
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** Virtual table cursor structure.
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*/
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struct Fts3tokCursor {
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sqlite3_vtab_cursor base; /* Base class used by SQLite core */
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char *zInput; /* Input string */
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sqlite3_tokenizer_cursor *pCsr; /* Cursor to iterate through zInput */
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int iRowid; /* Current 'rowid' value */
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const char *zToken; /* Current 'token' value */
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int nToken; /* Size of zToken in bytes */
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int iStart; /* Current 'start' value */
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int iEnd; /* Current 'end' value */
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int iPos; /* Current 'pos' value */
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};
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/*
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** Query FTS for the tokenizer implementation named zName.
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*/
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static int fts3tokQueryTokenizer(
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Fts3Hash *pHash,
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const char *zName,
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const sqlite3_tokenizer_module **pp,
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char **pzErr
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){
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sqlite3_tokenizer_module *p;
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int nName = (int)strlen(zName);
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p = (sqlite3_tokenizer_module *)sqlite3Fts3HashFind(pHash, zName, nName+1);
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if( !p ){
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sqlite3Fts3ErrMsg(pzErr, "unknown tokenizer: %s", zName);
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return SQLITE_ERROR;
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}
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*pp = p;
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return SQLITE_OK;
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}
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/*
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** The second argument, argv[], is an array of pointers to nul-terminated
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** strings. This function makes a copy of the array and strings into a
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** single block of memory. It then dequotes any of the strings that appear
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** to be quoted.
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**
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** If successful, output parameter *pazDequote is set to point at the
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** array of dequoted strings and SQLITE_OK is returned. The caller is
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** responsible for eventually calling sqlite3_free() to free the array
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** in this case. Or, if an error occurs, an SQLite error code is returned.
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** The final value of *pazDequote is undefined in this case.
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*/
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static int fts3tokDequoteArray(
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int argc, /* Number of elements in argv[] */
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const char * const *argv, /* Input array */
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char ***pazDequote /* Output array */
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){
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int rc = SQLITE_OK; /* Return code */
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if( argc==0 ){
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*pazDequote = 0;
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}else{
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int i;
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int nByte = 0;
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char **azDequote;
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for(i=0; i<argc; i++){
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nByte += (int)(strlen(argv[i]) + 1);
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}
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*pazDequote = azDequote = sqlite3_malloc64(sizeof(char *)*argc + nByte);
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if( azDequote==0 ){
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rc = SQLITE_NOMEM;
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}else{
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char *pSpace = (char *)&azDequote[argc];
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for(i=0; i<argc; i++){
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int n = (int)strlen(argv[i]);
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azDequote[i] = pSpace;
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memcpy(pSpace, argv[i], n+1);
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sqlite3Fts3Dequote(pSpace);
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pSpace += (n+1);
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}
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}
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}
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return rc;
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}
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/*
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** Schema of the tokenizer table.
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*/
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#define FTS3_TOK_SCHEMA "CREATE TABLE x(input, token, start, end, position)"
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/*
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** This function does all the work for both the xConnect and xCreate methods.
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** These tables have no persistent representation of their own, so xConnect
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** and xCreate are identical operations.
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**
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** argv[0]: module name
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** argv[1]: database name
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** argv[2]: table name
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** argv[3]: first argument (tokenizer name)
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*/
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static int fts3tokConnectMethod(
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sqlite3 *db, /* Database connection */
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void *pHash, /* Hash table of tokenizers */
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int argc, /* Number of elements in argv array */
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const char * const *argv, /* xCreate/xConnect argument array */
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sqlite3_vtab **ppVtab, /* OUT: New sqlite3_vtab object */
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char **pzErr /* OUT: sqlite3_malloc'd error message */
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){
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Fts3tokTable *pTab = 0;
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const sqlite3_tokenizer_module *pMod = 0;
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sqlite3_tokenizer *pTok = 0;
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int rc;
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char **azDequote = 0;
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int nDequote;
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rc = sqlite3_declare_vtab(db, FTS3_TOK_SCHEMA);
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if( rc!=SQLITE_OK ) return rc;
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nDequote = argc-3;
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rc = fts3tokDequoteArray(nDequote, &argv[3], &azDequote);
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if( rc==SQLITE_OK ){
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const char *zModule;
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if( nDequote<1 ){
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zModule = "simple";
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}else{
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zModule = azDequote[0];
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}
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rc = fts3tokQueryTokenizer((Fts3Hash*)pHash, zModule, &pMod, pzErr);
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}
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assert( (rc==SQLITE_OK)==(pMod!=0) );
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if( rc==SQLITE_OK ){
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const char * const *azArg = 0;
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if( nDequote>1 ) azArg = (const char * const *)&azDequote[1];
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rc = pMod->xCreate((nDequote>1 ? nDequote-1 : 0), azArg, &pTok);
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}
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if( rc==SQLITE_OK ){
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pTab = (Fts3tokTable *)sqlite3_malloc(sizeof(Fts3tokTable));
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if( pTab==0 ){
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rc = SQLITE_NOMEM;
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}
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}
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if( rc==SQLITE_OK ){
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memset(pTab, 0, sizeof(Fts3tokTable));
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pTab->pMod = pMod;
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pTab->pTok = pTok;
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*ppVtab = &pTab->base;
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}else{
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if( pTok ){
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pMod->xDestroy(pTok);
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}
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}
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sqlite3_free(azDequote);
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return rc;
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}
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/*
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** This function does the work for both the xDisconnect and xDestroy methods.
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** These tables have no persistent representation of their own, so xDisconnect
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** and xDestroy are identical operations.
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*/
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static int fts3tokDisconnectMethod(sqlite3_vtab *pVtab){
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Fts3tokTable *pTab = (Fts3tokTable *)pVtab;
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pTab->pMod->xDestroy(pTab->pTok);
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sqlite3_free(pTab);
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return SQLITE_OK;
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}
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/*
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** xBestIndex - Analyze a WHERE and ORDER BY clause.
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*/
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static int fts3tokBestIndexMethod(
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sqlite3_vtab *pVTab,
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sqlite3_index_info *pInfo
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){
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int i;
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UNUSED_PARAMETER(pVTab);
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for(i=0; i<pInfo->nConstraint; i++){
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if( pInfo->aConstraint[i].usable
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&& pInfo->aConstraint[i].iColumn==0
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&& pInfo->aConstraint[i].op==SQLITE_INDEX_CONSTRAINT_EQ
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){
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pInfo->idxNum = 1;
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pInfo->aConstraintUsage[i].argvIndex = 1;
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pInfo->aConstraintUsage[i].omit = 1;
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pInfo->estimatedCost = 1;
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return SQLITE_OK;
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}
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}
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pInfo->idxNum = 0;
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assert( pInfo->estimatedCost>1000000.0 );
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return SQLITE_OK;
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}
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/*
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** xOpen - Open a cursor.
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*/
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static int fts3tokOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
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Fts3tokCursor *pCsr;
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UNUSED_PARAMETER(pVTab);
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pCsr = (Fts3tokCursor *)sqlite3_malloc(sizeof(Fts3tokCursor));
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if( pCsr==0 ){
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return SQLITE_NOMEM;
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}
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memset(pCsr, 0, sizeof(Fts3tokCursor));
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*ppCsr = (sqlite3_vtab_cursor *)pCsr;
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return SQLITE_OK;
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}
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/*
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** Reset the tokenizer cursor passed as the only argument. As if it had
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** just been returned by fts3tokOpenMethod().
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*/
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static void fts3tokResetCursor(Fts3tokCursor *pCsr){
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if( pCsr->pCsr ){
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Fts3tokTable *pTab = (Fts3tokTable *)(pCsr->base.pVtab);
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pTab->pMod->xClose(pCsr->pCsr);
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pCsr->pCsr = 0;
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}
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sqlite3_free(pCsr->zInput);
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pCsr->zInput = 0;
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pCsr->zToken = 0;
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pCsr->nToken = 0;
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pCsr->iStart = 0;
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pCsr->iEnd = 0;
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pCsr->iPos = 0;
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pCsr->iRowid = 0;
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}
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/*
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** xClose - Close a cursor.
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*/
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static int fts3tokCloseMethod(sqlite3_vtab_cursor *pCursor){
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Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
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fts3tokResetCursor(pCsr);
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sqlite3_free(pCsr);
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return SQLITE_OK;
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}
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/*
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** xNext - Advance the cursor to the next row, if any.
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*/
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static int fts3tokNextMethod(sqlite3_vtab_cursor *pCursor){
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Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
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Fts3tokTable *pTab = (Fts3tokTable *)(pCursor->pVtab);
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int rc; /* Return code */
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pCsr->iRowid++;
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rc = pTab->pMod->xNext(pCsr->pCsr,
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&pCsr->zToken, &pCsr->nToken,
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&pCsr->iStart, &pCsr->iEnd, &pCsr->iPos
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);
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if( rc!=SQLITE_OK ){
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fts3tokResetCursor(pCsr);
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if( rc==SQLITE_DONE ) rc = SQLITE_OK;
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}
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return rc;
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}
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/*
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** xFilter - Initialize a cursor to point at the start of its data.
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*/
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static int fts3tokFilterMethod(
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sqlite3_vtab_cursor *pCursor, /* The cursor used for this query */
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int idxNum, /* Strategy index */
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const char *idxStr, /* Unused */
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int nVal, /* Number of elements in apVal */
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sqlite3_value **apVal /* Arguments for the indexing scheme */
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){
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int rc = SQLITE_ERROR;
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Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
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Fts3tokTable *pTab = (Fts3tokTable *)(pCursor->pVtab);
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UNUSED_PARAMETER(idxStr);
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UNUSED_PARAMETER(nVal);
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fts3tokResetCursor(pCsr);
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if( idxNum==1 ){
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const char *zByte = (const char *)sqlite3_value_text(apVal[0]);
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int nByte = sqlite3_value_bytes(apVal[0]);
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pCsr->zInput = sqlite3_malloc64(nByte+1);
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if( pCsr->zInput==0 ){
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rc = SQLITE_NOMEM;
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}else{
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if( nByte>0 ) memcpy(pCsr->zInput, zByte, nByte);
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pCsr->zInput[nByte] = 0;
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rc = pTab->pMod->xOpen(pTab->pTok, pCsr->zInput, nByte, &pCsr->pCsr);
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if( rc==SQLITE_OK ){
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pCsr->pCsr->pTokenizer = pTab->pTok;
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}
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}
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}
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if( rc!=SQLITE_OK ) return rc;
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return fts3tokNextMethod(pCursor);
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}
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/*
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** xEof - Return true if the cursor is at EOF, or false otherwise.
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*/
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static int fts3tokEofMethod(sqlite3_vtab_cursor *pCursor){
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Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
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return (pCsr->zToken==0);
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}
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/*
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** xColumn - Return a column value.
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*/
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static int fts3tokColumnMethod(
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sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */
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sqlite3_context *pCtx, /* Context for sqlite3_result_xxx() calls */
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int iCol /* Index of column to read value from */
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){
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Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
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/* CREATE TABLE x(input, token, start, end, position) */
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switch( iCol ){
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case 0:
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sqlite3_result_text(pCtx, pCsr->zInput, -1, SQLITE_TRANSIENT);
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break;
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case 1:
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sqlite3_result_text(pCtx, pCsr->zToken, pCsr->nToken, SQLITE_TRANSIENT);
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break;
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case 2:
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sqlite3_result_int(pCtx, pCsr->iStart);
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break;
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case 3:
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sqlite3_result_int(pCtx, pCsr->iEnd);
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break;
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default:
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assert( iCol==4 );
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sqlite3_result_int(pCtx, pCsr->iPos);
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break;
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}
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return SQLITE_OK;
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}
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/*
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** xRowid - Return the current rowid for the cursor.
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*/
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static int fts3tokRowidMethod(
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sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */
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sqlite_int64 *pRowid /* OUT: Rowid value */
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){
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Fts3tokCursor *pCsr = (Fts3tokCursor *)pCursor;
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*pRowid = (sqlite3_int64)pCsr->iRowid;
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return SQLITE_OK;
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}
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/*
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** Register the fts3tok module with database connection db. Return SQLITE_OK
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** if successful or an error code if sqlite3_create_module() fails.
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*/
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int sqlite3Fts3InitTok(sqlite3 *db, Fts3Hash *pHash){
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static const sqlite3_module fts3tok_module = {
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0, /* iVersion */
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fts3tokConnectMethod, /* xCreate */
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fts3tokConnectMethod, /* xConnect */
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fts3tokBestIndexMethod, /* xBestIndex */
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fts3tokDisconnectMethod, /* xDisconnect */
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fts3tokDisconnectMethod, /* xDestroy */
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fts3tokOpenMethod, /* xOpen */
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fts3tokCloseMethod, /* xClose */
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fts3tokFilterMethod, /* xFilter */
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fts3tokNextMethod, /* xNext */
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fts3tokEofMethod, /* xEof */
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fts3tokColumnMethod, /* xColumn */
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fts3tokRowidMethod, /* xRowid */
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0, /* xUpdate */
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0, /* xBegin */
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0, /* xSync */
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0, /* xCommit */
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0, /* xRollback */
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0, /* xFindFunction */
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0, /* xRename */
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0, /* xSavepoint */
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0, /* xRelease */
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0, /* xRollbackTo */
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0 /* xShadowName */
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};
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int rc; /* Return code */
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rc = sqlite3_create_module(db, "fts3tokenize", &fts3tok_module, (void*)pHash);
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return rc;
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}
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#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
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