222 lines
6.0 KiB
C
222 lines
6.0 KiB
C
/*
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** The author disclaims copyright to this source code.
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**
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*************************************************************************
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** Implementation of the "simple" full-text-search tokenizer.
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*/
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/*
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** The code in this file is only compiled if:
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**
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** * The FTS1 module is being built as an extension
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** (in which case SQLITE_CORE is not defined), or
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**
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** * The FTS1 module is being built into the core of
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** SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
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*/
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#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)
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#include <assert.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <ctype.h>
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#include "fts1_tokenizer.h"
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typedef struct simple_tokenizer {
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sqlite3_tokenizer base;
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char delim[128]; /* flag ASCII delimiters */
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} simple_tokenizer;
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typedef struct simple_tokenizer_cursor {
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sqlite3_tokenizer_cursor base;
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const char *pInput; /* input we are tokenizing */
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int nBytes; /* size of the input */
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int iOffset; /* current position in pInput */
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int iToken; /* index of next token to be returned */
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char *pToken; /* storage for current token */
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int nTokenAllocated; /* space allocated to zToken buffer */
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} simple_tokenizer_cursor;
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/* Forward declaration */
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static const sqlite3_tokenizer_module simpleTokenizerModule;
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static int isDelim(simple_tokenizer *t, unsigned char c){
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return c<0x80 && t->delim[c];
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}
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/*
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** Create a new tokenizer instance.
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*/
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static int simpleCreate(
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int argc, const char * const *argv,
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sqlite3_tokenizer **ppTokenizer
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){
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simple_tokenizer *t;
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t = (simple_tokenizer *) calloc(sizeof(*t), 1);
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if( t==NULL ) return SQLITE_NOMEM;
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/* TODO(shess) Delimiters need to remain the same from run to run,
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** else we need to reindex. One solution would be a meta-table to
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** track such information in the database, then we'd only want this
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** information on the initial create.
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*/
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if( argc>1 ){
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int i, n = strlen(argv[1]);
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for(i=0; i<n; i++){
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unsigned char ch = argv[1][i];
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/* We explicitly don't support UTF-8 delimiters for now. */
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if( ch>=0x80 ){
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free(t);
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return SQLITE_ERROR;
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}
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t->delim[ch] = 1;
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}
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} else {
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/* Mark non-alphanumeric ASCII characters as delimiters */
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int i;
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for(i=1; i<0x80; i++){
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t->delim[i] = !isalnum(i);
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}
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}
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*ppTokenizer = &t->base;
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return SQLITE_OK;
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}
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/*
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** Destroy a tokenizer
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*/
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static int simpleDestroy(sqlite3_tokenizer *pTokenizer){
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free(pTokenizer);
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return SQLITE_OK;
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}
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/*
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** Prepare to begin tokenizing a particular string. The input
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** string to be tokenized is pInput[0..nBytes-1]. A cursor
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** used to incrementally tokenize this string is returned in
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** *ppCursor.
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*/
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static int simpleOpen(
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sqlite3_tokenizer *pTokenizer, /* The tokenizer */
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const char *pInput, int nBytes, /* String to be tokenized */
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sqlite3_tokenizer_cursor **ppCursor /* OUT: Tokenization cursor */
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){
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simple_tokenizer_cursor *c;
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c = (simple_tokenizer_cursor *) malloc(sizeof(*c));
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if( c==NULL ) return SQLITE_NOMEM;
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c->pInput = pInput;
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if( pInput==0 ){
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c->nBytes = 0;
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}else if( nBytes<0 ){
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c->nBytes = (int)strlen(pInput);
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}else{
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c->nBytes = nBytes;
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}
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c->iOffset = 0; /* start tokenizing at the beginning */
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c->iToken = 0;
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c->pToken = NULL; /* no space allocated, yet. */
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c->nTokenAllocated = 0;
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*ppCursor = &c->base;
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return SQLITE_OK;
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}
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/*
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** Close a tokenization cursor previously opened by a call to
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** simpleOpen() above.
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*/
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static int simpleClose(sqlite3_tokenizer_cursor *pCursor){
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simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
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free(c->pToken);
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free(c);
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return SQLITE_OK;
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}
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/*
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** Extract the next token from a tokenization cursor. The cursor must
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** have been opened by a prior call to simpleOpen().
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*/
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static int simpleNext(
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sqlite3_tokenizer_cursor *pCursor, /* Cursor returned by simpleOpen */
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const char **ppToken, /* OUT: *ppToken is the token text */
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int *pnBytes, /* OUT: Number of bytes in token */
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int *piStartOffset, /* OUT: Starting offset of token */
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int *piEndOffset, /* OUT: Ending offset of token */
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int *piPosition /* OUT: Position integer of token */
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){
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simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
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simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer;
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unsigned char *p = (unsigned char *)c->pInput;
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while( c->iOffset<c->nBytes ){
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int iStartOffset;
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/* Scan past delimiter characters */
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while( c->iOffset<c->nBytes && isDelim(t, p[c->iOffset]) ){
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c->iOffset++;
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}
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/* Count non-delimiter characters. */
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iStartOffset = c->iOffset;
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while( c->iOffset<c->nBytes && !isDelim(t, p[c->iOffset]) ){
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c->iOffset++;
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}
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if( c->iOffset>iStartOffset ){
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int i, n = c->iOffset-iStartOffset;
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if( n>c->nTokenAllocated ){
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c->nTokenAllocated = n+20;
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c->pToken = realloc(c->pToken, c->nTokenAllocated);
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if( c->pToken==NULL ) return SQLITE_NOMEM;
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}
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for(i=0; i<n; i++){
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/* TODO(shess) This needs expansion to handle UTF-8
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** case-insensitivity.
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*/
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unsigned char ch = p[iStartOffset+i];
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c->pToken[i] = ch<0x80 ? tolower(ch) : ch;
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}
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*ppToken = c->pToken;
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*pnBytes = n;
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*piStartOffset = iStartOffset;
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*piEndOffset = c->iOffset;
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*piPosition = c->iToken++;
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return SQLITE_OK;
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}
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}
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return SQLITE_DONE;
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}
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/*
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** The set of routines that implement the simple tokenizer
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*/
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static const sqlite3_tokenizer_module simpleTokenizerModule = {
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0,
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simpleCreate,
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simpleDestroy,
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simpleOpen,
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simpleClose,
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simpleNext,
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};
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/*
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** Allocate a new simple tokenizer. Return a pointer to the new
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** tokenizer in *ppModule
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*/
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void sqlite3Fts1SimpleTokenizerModule(
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sqlite3_tokenizer_module const**ppModule
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){
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*ppModule = &simpleTokenizerModule;
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}
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#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */
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