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/*
** The author disclaims copyright to this source code.
**
*************************************************************************
** Implementation of the "simple" full-text-search tokenizer.
*/
#include <assert.h>
#if !defined(__APPLE__)
#include <malloc.h>
#else
#include <stdlib.h>
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "tokenizer.h"
/* Duplicate a string; the caller must free() the returned string.
* (We don't use strdup() since it's not part of the standard C library and
* may not be available everywhere.) */
/* TODO(shess) Copied from fulltext.c, consider util.c for such
** things. */
static char *string_dup(const char *s){
char *str = malloc(strlen(s) + 1);
strcpy(str, s);
return str;
}
typedef struct simple_tokenizer {
sqlite3_tokenizer base;
const char *zDelim; /* token delimiters */
} simple_tokenizer;
typedef struct simple_tokenizer_cursor {
sqlite3_tokenizer_cursor base;
const char *pInput; /* input we are tokenizing */
int nBytes; /* size of the input */
const char *pCurrent; /* current position in pInput */
int iToken; /* index of next token to be returned */
char *zToken; /* storage for current token */
int nTokenBytes; /* actual size of current token */
int nTokenAllocated; /* space allocated to zToken buffer */
} simple_tokenizer_cursor;
static sqlite3_tokenizer_module simpleTokenizerModule;/* forward declaration */
static int simpleCreate(
int argc, const char **argv,
sqlite3_tokenizer **ppTokenizer
){
simple_tokenizer *t;
t = (simple_tokenizer *) malloc(sizeof(simple_tokenizer));
/* TODO(shess) Delimiters need to remain the same from run to run,
** else we need to reindex. One solution would be a meta-table to
** track such information in the database, then we'd only want this
** information on the initial create.
*/
if( argc>1 ){
t->zDelim = string_dup(argv[1]);
} else {
/* Build a string excluding alphanumeric ASCII characters */
char zDelim[0x80]; /* nul-terminated, so nul not a member */
int i, j;
for(i=1, j=0; i<0x80; i++){
if( !isalnum(i) ){
zDelim[j++] = i;
}
}
zDelim[j++] = '\0';
assert( j<=sizeof(zDelim) );
t->zDelim = string_dup(zDelim);
}
*ppTokenizer = &t->base;
return SQLITE_OK;
}
static int simpleDestroy(sqlite3_tokenizer *pTokenizer){
simple_tokenizer *t = (simple_tokenizer *) pTokenizer;
free((void *) t->zDelim);
free(t);
return SQLITE_OK;
}
static int simpleOpen(
sqlite3_tokenizer *pTokenizer,
const char *pInput, int nBytes,
sqlite3_tokenizer_cursor **ppCursor
){
simple_tokenizer_cursor *c;
c = (simple_tokenizer_cursor *) malloc(sizeof(simple_tokenizer_cursor));
c->pInput = pInput;
c->nBytes = nBytes<0 ? (int) strlen(pInput) : nBytes;
c->pCurrent = c->pInput; /* start tokenizing at the beginning */
c->iToken = 0;
c->zToken = NULL; /* no space allocated, yet. */
c->nTokenBytes = 0;
c->nTokenAllocated = 0;
*ppCursor = &c->base;
return SQLITE_OK;
}
static int simpleClose(sqlite3_tokenizer_cursor *pCursor){
simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
if( NULL!=c->zToken ){
free(c->zToken);
}
free(c);
return SQLITE_OK;
}
static int simpleNext(
sqlite3_tokenizer_cursor *pCursor,
const char **ppToken, int *pnBytes,
int *piStartOffset, int *piEndOffset, int *piPosition
){
simple_tokenizer_cursor *c = (simple_tokenizer_cursor *) pCursor;
simple_tokenizer *t = (simple_tokenizer *) pCursor->pTokenizer;
int ii;
while( c->pCurrent-c->pInput<c->nBytes ){
int n = (int) strcspn(c->pCurrent, t->zDelim);
if( n>0 ){
if( n+1>c->nTokenAllocated ){
c->zToken = realloc(c->zToken, n+1);
}
for(ii=0; ii<n; ii++){
/* TODO(shess) This needs expansion to handle UTF-8
** case-insensitivity.
*/
char ch = c->pCurrent[ii];
c->zToken[ii] = (unsigned char)ch<0x80 ? tolower(ch) : ch;
}
c->zToken[n] = '\0';
*ppToken = c->zToken;
*pnBytes = n;
*piStartOffset = (int) (c->pCurrent-c->pInput);
*piEndOffset = *piStartOffset+n;
*piPosition = c->iToken++;
c->pCurrent += n + 1;
return SQLITE_OK;
}
c->pCurrent += n + 1;
/* TODO(shess) could strspn() to skip delimiters en masse. Needs
** to happen in two places, though, which is annoying.
*/
}
return SQLITE_DONE;
}
static sqlite3_tokenizer_module simpleTokenizerModule = {
0,
simpleCreate,
simpleDestroy,
simpleOpen,
simpleClose,
simpleNext,
};
void get_simple_tokenizer_module(
sqlite3_tokenizer_module **ppModule
){
*ppModule = &simpleTokenizerModule;
}
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