1512 lines
44 KiB
C
1512 lines
44 KiB
C
/* The author disclaims copyright to this source code.
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*
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* This is an SQLite module implementing full-text search.
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*/
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#include <assert.h>
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#if !defined(__APPLE__)
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#include <malloc.h>
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#else
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#include <stdlib.h>
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#endif
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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 "fulltext.h"
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#include "ft_hash.h"
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#include "tokenizer.h"
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#include "sqlite3.h"
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#include "sqlite3ext.h"
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SQLITE_EXTENSION_INIT1
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/* utility functions */
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/* We encode variable-length integers in little-endian order using seven bits
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* per byte as follows:
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**
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** KEY:
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** A = 0xxxxxxx 7 bits of data and one flag bit
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** B = 1xxxxxxx 7 bits of data and one flag bit
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**
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** 7 bits - A
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** 14 bits - BA
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** 21 bits - BBA
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** and so on.
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*/
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/* We may need up to VARINT_MAX bytes to store an encoded 64-bit integer. */
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#define VARINT_MAX 10
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/* Write a 64-bit variable-length integer to memory starting at p[0].
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* The length of data written will be between 1 and VARINT_MAX bytes.
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* The number of bytes written is returned. */
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static int putVarint(char *p, sqlite_int64 v){
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unsigned char *q = (unsigned char *) p;
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sqlite_uint64 vu = v;
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do{
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*q++ = (unsigned char) ((vu & 0x7f) | 0x80);
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vu >>= 7;
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}while( vu!=0 );
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q[-1] &= 0x7f; /* turn off high bit in final byte */
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assert( q - (unsigned char *)p <= VARINT_MAX );
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return (int) (q - (unsigned char *)p);
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}
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/* Read a 64-bit variable-length integer from memory starting at p[0].
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* Return the number of bytes read, or 0 on error.
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* The value is stored in *v. */
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static int getVarint(const char *p, sqlite_int64 *v){
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const unsigned char *q = (const unsigned char *) p;
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sqlite_uint64 x = 0, y = 1;
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while( (*q & 0x80) == 0x80 ){
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x += y * (*q++ & 0x7f);
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y <<= 7;
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if( q - (unsigned char *)p >= VARINT_MAX ){ /* bad data */
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assert( 0 );
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return 0;
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}
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}
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x += y * (*q++);
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*v = (sqlite_int64) x;
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return (int) (q - (unsigned char *)p);
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}
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static int getVarint32(const char *p, int *pi){
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sqlite_int64 i;
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int ret = getVarint(p, &i);
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*pi = (int) i;
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assert( *pi==i );
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return ret;
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}
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/*** Document lists ***
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*
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* A document list holds a sorted list of varint-encoded document IDs.
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*
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* A doclist with type DL_POSITIONS_OFFSETS is stored like this:
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*
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* array {
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* varint docid;
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* array {
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* varint position; (delta from previous position plus 1, or 0 for end)
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* varint startOffset; (delta from previous startOffset)
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* varint endOffset; (delta from startOffset)
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* }
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* }
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*
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* Here, array { X } means zero or more occurrences of X, adjacent in memory.
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*
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* A doclist with type DL_POSITIONS is like the above, but holds only docids
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* and positions without offset information.
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*
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* A doclist with type DL_DOCIDS is like the above, but holds only docids
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* without positions or offset information.
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*
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* On disk, every document list has positions and offsets, so we don't bother
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* to serialize a doclist's type.
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*
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* We don't yet delta-encode document IDs; doing so will probably be a
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* modest win.
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*
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* NOTE(shess) I've thought of a slightly (1%) better offset encoding.
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* After the first offset, estimate the next offset by using the
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* current token position and the previous token position and offset,
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* offset to handle some variance. So the estimate would be
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* (iPosition*w->iStartOffset/w->iPosition-64), which is delta-encoded
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* as normal. Offsets more than 64 chars from the estimate are
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* encoded as the delta to the previous start offset + 128. An
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* additional tiny increment can be gained by using the end offset of
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* the previous token to make the estimate a tiny bit more precise.
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*/
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typedef enum DocListType {
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DL_DOCIDS, /* docids only */
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DL_POSITIONS, /* docids + positions */
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DL_POSITIONS_OFFSETS /* docids + positions + offsets */
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} DocListType;
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typedef struct DocList {
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char *pData;
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int nData;
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DocListType iType;
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int iLastPos; /* the last position written */
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int iLastOffset; /* the last start offset written */
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} DocList;
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/* Initialize a new DocList to hold the given data. */
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static void docListInit(DocList *d, DocListType iType,
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const char *pData, int nData){
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d->nData = nData;
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if( nData>0 ){
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d->pData = malloc(nData);
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memcpy(d->pData, pData, nData);
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} else {
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d->pData = NULL;
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}
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d->iType = iType;
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d->iLastPos = 0;
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d->iLastOffset = 0;
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}
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/* Create a new dynamically-allocated DocList. */
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static DocList *docListNew(DocListType iType){
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DocList *d = (DocList *) malloc(sizeof(DocList));
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docListInit(d, iType, 0, 0);
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return d;
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}
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static void docListDestroy(DocList *d){
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free(d->pData);
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#ifndef NDEBUG
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memset(d, 0x55, sizeof(*d));
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#endif
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}
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static void docListDelete(DocList *d){
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docListDestroy(d);
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free(d);
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}
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static char *docListEnd(DocList *d){
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return d->pData + d->nData;
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}
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/* Append a varint to a DocList's data. */
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static void appendVarint(DocList *d, sqlite_int64 i){
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char c[VARINT_MAX];
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int n = putVarint(c, i);
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d->pData = realloc(d->pData, d->nData + n);
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memcpy(d->pData + d->nData, c, n);
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d->nData += n;
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}
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static void docListAddDocid(DocList *d, sqlite_int64 iDocid){
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appendVarint(d, iDocid);
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d->iLastPos = 0;
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}
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/* Add a position to the last position list in a doclist. */
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static void docListAddPos(DocList *d, int iPos){
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assert( d->iType>=DL_POSITIONS );
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appendVarint(d, iPos-d->iLastPos+1);
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d->iLastPos = iPos;
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}
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static void docListAddPosOffset(DocList *d, int iPos,
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int iStartOffset, int iEndOffset){
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assert( d->iType==DL_POSITIONS_OFFSETS );
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docListAddPos(d, iPos);
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appendVarint(d, iStartOffset-d->iLastOffset);
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d->iLastOffset = iStartOffset;
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appendVarint(d, iEndOffset-iStartOffset);
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}
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/* Terminate the last position list in the given doclist. */
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static void docListAddEndPos(DocList *d){
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appendVarint(d, 0);
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}
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typedef struct DocListReader {
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DocList *pDoclist;
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char *p;
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int iLastPos; /* the last position read */
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} DocListReader;
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static void readerInit(DocListReader *r, DocList *pDoclist){
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r->pDoclist = pDoclist;
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if( pDoclist!=NULL ){
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r->p = pDoclist->pData;
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}
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r->iLastPos = 0;
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}
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static int readerAtEnd(DocListReader *pReader){
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return pReader->p >= docListEnd(pReader->pDoclist);
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}
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/* Peek at the next docid without advancing the read pointer. */
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static sqlite_int64 peekDocid(DocListReader *pReader){
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sqlite_int64 ret;
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assert( !readerAtEnd(pReader) );
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getVarint(pReader->p, &ret);
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return ret;
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}
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/* Read the next docid. */
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static sqlite_int64 readDocid(DocListReader *pReader){
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sqlite_int64 ret;
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assert( !readerAtEnd(pReader) );
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pReader->p += getVarint(pReader->p, &ret);
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pReader->iLastPos = 0;
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return ret;
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}
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/* Read the next position from a position list.
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* Returns the position, or -1 at the end of the list. */
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static int readPosition(DocListReader *pReader){
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int i;
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int iType = pReader->pDoclist->iType;
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assert( iType>=DL_POSITIONS );
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assert( !readerAtEnd(pReader) );
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pReader->p += getVarint32(pReader->p, &i);
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if( i==0 ){
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pReader->iLastPos = -1;
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return -1;
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}
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pReader->iLastPos += ((int) i)-1;
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if( iType>=DL_POSITIONS_OFFSETS ){
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/* Skip over offsets, ignoring them for now. */
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int iStart, iEnd;
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pReader->p += getVarint32(pReader->p, &iStart);
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pReader->p += getVarint32(pReader->p, &iEnd);
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}
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return pReader->iLastPos;
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}
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/* Skip past the end of a position list. */
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static void skipPositionList(DocListReader *pReader){
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while( readPosition(pReader)!=-1 )
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;
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}
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/* Skip over a docid, including its position list if the doclist has
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* positions. */
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static void skipDocument(DocListReader *pReader){
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readDocid(pReader);
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if( pReader->pDoclist->iType >= DL_POSITIONS ){
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skipPositionList(pReader);
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}
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}
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static sqlite_int64 firstDocid(DocList *d){
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DocListReader r;
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readerInit(&r, d);
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return readDocid(&r);
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}
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/* Doclist multi-tool. Pass pUpdate==NULL to delete the indicated docid;
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* otherwise pUpdate, which must contain only the single docid [iDocid], is
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* inserted (if not present) or updated (if already present). */
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static int docListUpdate(DocList *d, sqlite_int64 iDocid, DocList *pUpdate){
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int modified = 0;
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DocListReader reader;
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char *p;
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if( pUpdate!=NULL ){
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assert( d->iType==pUpdate->iType);
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assert( iDocid==firstDocid(pUpdate) );
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}
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readerInit(&reader, d);
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while( !readerAtEnd(&reader) && peekDocid(&reader)<iDocid ){
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skipDocument(&reader);
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}
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p = reader.p;
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/* Delete if there is a matching element. */
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if( !readerAtEnd(&reader) && iDocid==peekDocid(&reader) ){
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skipDocument(&reader);
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memmove(p, reader.p, docListEnd(d) - reader.p);
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d->nData -= (reader.p - p);
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modified = 1;
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}
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/* Insert if indicated. */
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if( pUpdate!=NULL ){
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int iDoclist = p-d->pData;
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docListAddEndPos(pUpdate);
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d->pData = realloc(d->pData, d->nData+pUpdate->nData);
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p = d->pData + iDoclist;
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memmove(p+pUpdate->nData, p, docListEnd(d) - p);
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memcpy(p, pUpdate->pData, pUpdate->nData);
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d->nData += pUpdate->nData;
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modified = 1;
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}
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return modified;
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}
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/* Split the second half of doclist d into a separate doclist d2. Returns 1
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* if successful, or 0 if d contains a single document and hence can't be
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* split. */
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static int docListSplit(DocList *d, DocList *d2){
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const char *pSplitPoint = d->pData + d->nData / 2;
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DocListReader reader;
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readerInit(&reader, d);
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while( reader.p<pSplitPoint ){
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skipDocument(&reader);
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}
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if( readerAtEnd(&reader) ) return 0;
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docListInit(d2, d->iType, reader.p, docListEnd(d) - reader.p);
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d->nData = reader.p - d->pData;
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d->pData = realloc(d->pData, d->nData);
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return 1;
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}
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/* A DocListMerge computes the AND of an in-memory DocList [in] and a chunked
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* on-disk doclist, resulting in another in-memory DocList [out]. [in]
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* and [out] may or may not store position information according to the
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* caller's wishes. The on-disk doclist always comes with positions.
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*
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* The caller must read each chunk of the on-disk doclist in succession and
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* pass it to mergeBlock().
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*
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* If [in] has positions, then the merge output contains only documents with
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* matching positions in the two input doclists. If [in] does not have
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* positions, then the merge output contains all documents common to the two
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* input doclists.
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*
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* If [in] is NULL, then the on-disk doclist is copied to [out] directly.
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*
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* A merge is performed using an integer [iOffset] provided by the caller.
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* [iOffset] is subtracted from each position in the on-disk doclist for the
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* purpose of position comparison; this is helpful in implementing phrase
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* searches.
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*
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* A DocListMerge is not yet able to propagate offsets through query
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* processing; we should add that capability soon.
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*/
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typedef struct DocListMerge {
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DocListReader in;
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DocList *pOut;
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int iOffset;
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} DocListMerge;
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static void mergeInit(DocListMerge *m,
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DocList *pIn, int iOffset, DocList *pOut){
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readerInit(&m->in, pIn);
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m->pOut = pOut;
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m->iOffset = iOffset;
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/* can't handle offsets yet */
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assert( pIn==NULL || pIn->iType <= DL_POSITIONS );
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assert( pOut->iType <= DL_POSITIONS );
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}
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/* A helper function for mergeBlock(), below. Merge the position lists
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* pointed to by m->in and pBlockReader.
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* If the merge matches, write [iDocid] to m->pOut; if m->pOut
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* has positions then write all matching positions as well. */
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static void mergePosList(DocListMerge *m, sqlite_int64 iDocid,
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DocListReader *pBlockReader){
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int block_pos = readPosition(pBlockReader);
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int in_pos = readPosition(&m->in);
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int match = 0;
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while( block_pos!=-1 || in_pos!=-1 ){
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if( block_pos-m->iOffset==in_pos ){
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if( !match ){
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docListAddDocid(m->pOut, iDocid);
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match = 1;
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}
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if( m->pOut->iType >= DL_POSITIONS ){
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docListAddPos(m->pOut, in_pos);
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}
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block_pos = readPosition(pBlockReader);
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in_pos = readPosition(&m->in);
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} else if( in_pos==-1 || (block_pos!=-1 && block_pos-m->iOffset<in_pos) ){
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block_pos = readPosition(pBlockReader);
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} else {
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in_pos = readPosition(&m->in);
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}
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}
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if( m->pOut->iType >= DL_POSITIONS && match ){
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docListAddEndPos(m->pOut);
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}
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}
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/* Merge one block of an on-disk doclist into a DocListMerge. */
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static void mergeBlock(DocListMerge *m, DocList *pBlock){
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DocListReader blockReader;
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assert( pBlock->iType >= DL_POSITIONS );
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readerInit(&blockReader, pBlock);
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while( !readerAtEnd(&blockReader) ){
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sqlite_int64 iDocid = readDocid(&blockReader);
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if( m->in.pDoclist!=NULL ){
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while( 1 ){
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if( readerAtEnd(&m->in) ) return; /* nothing more to merge */
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if( peekDocid(&m->in)>=iDocid ) break;
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skipDocument(&m->in);
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}
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if( peekDocid(&m->in)>iDocid ){ /* [pIn] has no match with iDocid */
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skipPositionList(&blockReader); /* skip this docid in the block */
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continue;
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}
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readDocid(&m->in);
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}
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/* We have a document match. */
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if( m->in.pDoclist==NULL || m->in.pDoclist->iType < DL_POSITIONS ){
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/* We don't need to do a poslist merge. */
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docListAddDocid(m->pOut, iDocid);
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if( m->pOut->iType >= DL_POSITIONS ){
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/* Copy all positions to the output doclist. */
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while( 1 ){
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int pos = readPosition(&blockReader);
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if( pos==-1 ) break;
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docListAddPos(m->pOut, pos);
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}
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docListAddEndPos(m->pOut);
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} else skipPositionList(&blockReader);
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continue;
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}
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mergePosList(m, iDocid, &blockReader);
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}
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}
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static char *string_dup_n(const char *s, int n){
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char *str = malloc(n + 1);
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memcpy(str, s, n);
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str[n] = '\0';
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return str;
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}
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/* Duplicate a string; the caller must free() the returned string.
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* (We don't use strdup() since it's not part of the standard C library and
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* may not be available everywhere.) */
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static char *string_dup(const char *s){
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return string_dup_n(s, strlen(s));
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}
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/* Format a string, replacing each occurrence of the % character with
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* zName. This may be more convenient than sqlite_mprintf()
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* when one string is used repeatedly in a format string.
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* The caller must free() the returned string. */
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static char *string_format(const char *zFormat, const char *zName){
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const char *p;
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size_t len = 0;
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size_t nName = strlen(zName);
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char *result;
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char *r;
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/* first compute length needed */
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for(p = zFormat ; *p ; ++p){
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len += (*p=='%' ? nName : 1);
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}
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len += 1; /* for null terminator */
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r = result = malloc(len);
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for(p = zFormat; *p; ++p){
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if( *p=='%' ){
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memcpy(r, zName, nName);
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r += nName;
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} else {
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*r++ = *p;
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}
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}
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*r++ = '\0';
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assert( r == result + len );
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return result;
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}
|
|
|
|
static int sql_exec(sqlite3 *db, const char *zName, const char *zFormat){
|
|
char *zCommand = string_format(zFormat, zName);
|
|
int rc = sqlite3_exec(db, zCommand, NULL, 0, NULL);
|
|
free(zCommand);
|
|
return rc;
|
|
}
|
|
|
|
static int sql_prepare(sqlite3 *db, const char *zName, sqlite3_stmt **ppStmt,
|
|
const char *zFormat){
|
|
char *zCommand = string_format(zFormat, zName);
|
|
int rc = sqlite3_prepare(db, zCommand, -1, ppStmt, NULL);
|
|
free(zCommand);
|
|
return rc;
|
|
}
|
|
|
|
/* end utility functions */
|
|
|
|
#define QUERY_GENERIC 0
|
|
#define QUERY_FULLTEXT 1
|
|
|
|
#define CHUNK_MAX 1024
|
|
|
|
typedef enum fulltext_statement {
|
|
CONTENT_INSERT_STMT,
|
|
CONTENT_SELECT_STMT,
|
|
CONTENT_DELETE_STMT,
|
|
|
|
TERM_SELECT_STMT,
|
|
TERM_CHUNK_SELECT_STMT,
|
|
TERM_INSERT_STMT,
|
|
TERM_UPDATE_STMT,
|
|
TERM_DELETE_STMT,
|
|
|
|
MAX_STMT /* Always at end! */
|
|
} fulltext_statement;
|
|
|
|
/* These must exactly match the enum above. */
|
|
/* TODO(adam): Is there some risk that a statement (in particular,
|
|
** pTermSelectStmt) will be used in two cursors at once, e.g. if a
|
|
** query joins a virtual table to itself? If so perhaps we should
|
|
** move some of these to the cursor object.
|
|
*/
|
|
static const char *fulltext_zStatement[MAX_STMT] = {
|
|
/* CONTENT_INSERT */ "insert into %_content (rowid, content) values (?, ?)",
|
|
/* CONTENT_SELECT */ "select content from %_content where rowid = ?",
|
|
/* CONTENT_DELETE */ "delete from %_content where rowid = ?",
|
|
|
|
/* TERM_SELECT */
|
|
"select rowid, doclist from %_term where term = ? and first = ?",
|
|
/* TERM_CHUNK_SELECT */
|
|
"select max(first) from %_term where term = ? and first <= ?",
|
|
/* TERM_INSERT */
|
|
"insert into %_term (term, first, doclist) values (?, ?, ?)",
|
|
/* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
|
|
/* TERM_DELETE */ "delete from %_term where rowid = ?",
|
|
};
|
|
|
|
typedef struct fulltext_vtab {
|
|
sqlite3_vtab base;
|
|
sqlite3 *db;
|
|
const char *zName; /* virtual table name */
|
|
sqlite3_tokenizer *pTokenizer; /* tokenizer for inserts and queries */
|
|
|
|
/* Precompiled statements which we keep as long as the table is
|
|
** open.
|
|
*/
|
|
sqlite3_stmt *pFulltextStatements[MAX_STMT];
|
|
} fulltext_vtab;
|
|
|
|
typedef struct fulltext_cursor {
|
|
sqlite3_vtab_cursor base;
|
|
int iCursorType; /* QUERY_GENERIC or QUERY_FULLTEXT */
|
|
|
|
sqlite3_stmt *pStmt;
|
|
|
|
int eof;
|
|
|
|
/* The following is used only when iCursorType == QUERY_FULLTEXT. */
|
|
DocListReader result;
|
|
} fulltext_cursor;
|
|
|
|
static struct fulltext_vtab *cursor_vtab(fulltext_cursor *c){
|
|
return (fulltext_vtab *) c->base.pVtab;
|
|
}
|
|
|
|
static sqlite3_module fulltextModule; /* forward declaration */
|
|
|
|
/* Puts a freshly-prepared statement determined by iStmt in *ppStmt.
|
|
** If the indicated statement has never been prepared, it is prepared
|
|
** and cached, otherwise the cached version is reset.
|
|
*/
|
|
static int sql_get_statement(fulltext_vtab *v, fulltext_statement iStmt,
|
|
sqlite3_stmt **ppStmt){
|
|
assert( iStmt<MAX_STMT );
|
|
if( v->pFulltextStatements[iStmt]==NULL ){
|
|
int rc = sql_prepare(v->db, v->zName, &v->pFulltextStatements[iStmt],
|
|
fulltext_zStatement[iStmt]);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
} else {
|
|
int rc = sqlite3_reset(v->pFulltextStatements[iStmt]);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
}
|
|
|
|
*ppStmt = v->pFulltextStatements[iStmt];
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* Step the indicated statement, handling errors SQLITE_BUSY (by
|
|
** retrying) and SQLITE_SCHEMA (by re-preparing and transferring
|
|
** bindings to the new statement).
|
|
** TODO(adam): We should extend this function so that it can work with
|
|
** statements declared locally, not only globally cached statements.
|
|
*/
|
|
static int sql_step_statement(fulltext_vtab *v, fulltext_statement iStmt,
|
|
sqlite3_stmt **ppStmt){
|
|
int rc;
|
|
sqlite3_stmt *s = *ppStmt;
|
|
assert( iStmt<MAX_STMT );
|
|
assert( s==v->pFulltextStatements[iStmt] );
|
|
|
|
while( (rc=sqlite3_step(s))!=SQLITE_DONE && rc!=SQLITE_ROW ){
|
|
sqlite3_stmt *pNewStmt;
|
|
|
|
if( rc==SQLITE_BUSY ) continue;
|
|
if( rc!=SQLITE_ERROR ) return rc;
|
|
|
|
rc = sqlite3_reset(s);
|
|
if( rc!=SQLITE_SCHEMA ) return SQLITE_ERROR;
|
|
|
|
v->pFulltextStatements[iStmt] = NULL; /* Still in s */
|
|
rc = sql_get_statement(v, iStmt, &pNewStmt);
|
|
if( rc!=SQLITE_OK ) goto err;
|
|
*ppStmt = pNewStmt;
|
|
|
|
rc = sqlite3_transfer_bindings(s, pNewStmt);
|
|
if( rc!=SQLITE_OK ) goto err;
|
|
|
|
rc = sqlite3_finalize(s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
s = pNewStmt;
|
|
}
|
|
return rc;
|
|
|
|
err:
|
|
sqlite3_finalize(s);
|
|
return rc;
|
|
}
|
|
|
|
/* Like sql_step_statement(), but convert SQLITE_DONE to SQLITE_OK.
|
|
** Useful for statements like UPDATE, where we expect no results.
|
|
*/
|
|
static int sql_single_step_statement(fulltext_vtab *v,
|
|
fulltext_statement iStmt,
|
|
sqlite3_stmt **ppStmt){
|
|
int rc = sql_step_statement(v, iStmt, ppStmt);
|
|
return (rc==SQLITE_DONE) ? SQLITE_OK : rc;
|
|
}
|
|
|
|
/* insert into %_content (rowid, content) values ([rowid], [zContent]) */
|
|
static int content_insert(fulltext_vtab *v, sqlite3_value *rowid,
|
|
const char *zContent, int nContent){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, CONTENT_INSERT_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_value(s, 1, rowid);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_text(s, 2, zContent, nContent, SQLITE_STATIC);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return sql_single_step_statement(v, CONTENT_INSERT_STMT, &s);
|
|
}
|
|
|
|
/* select content from %_content where rowid = [iRow]
|
|
* The caller must delete the returned string. */
|
|
static int content_select(fulltext_vtab *v, sqlite_int64 iRow,
|
|
char **pzContent){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, CONTENT_SELECT_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 1, iRow);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sql_step_statement(v, CONTENT_SELECT_STMT, &s);
|
|
if( rc!=SQLITE_ROW ) return rc;
|
|
|
|
*pzContent = string_dup((const char *)sqlite3_column_text(s, 0));
|
|
|
|
/* We expect only one row. We must execute another sqlite3_step()
|
|
* to complete the iteration; otherwise the table will remain locked. */
|
|
rc = sqlite3_step(s);
|
|
if( rc==SQLITE_DONE ) return SQLITE_OK;
|
|
|
|
free(*pzContent);
|
|
return rc;
|
|
}
|
|
|
|
/* delete from %_content where rowid = [iRow ] */
|
|
static int content_delete(fulltext_vtab *v, sqlite_int64 iRow){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, CONTENT_DELETE_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 1, iRow);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return sql_single_step_statement(v, CONTENT_DELETE_STMT, &s);
|
|
}
|
|
|
|
/* select rowid, doclist from %_term where term = [zTerm] and first = [iFirst]
|
|
* If found, returns SQLITE_OK; the caller must free the returned doclist.
|
|
* If no rows found, returns SQLITE_ERROR. */
|
|
static int term_select(fulltext_vtab *v, const char *zTerm, int nTerm,
|
|
sqlite_int64 iFirst,
|
|
sqlite_int64 *rowid,
|
|
DocList *out){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, TERM_SELECT_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_text(s, 1, zTerm, nTerm, SQLITE_TRANSIENT);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 2, iFirst);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
|
|
if( rc!=SQLITE_ROW ) return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
|
|
|
|
*rowid = sqlite3_column_int64(s, 0);
|
|
docListInit(out, DL_POSITIONS_OFFSETS,
|
|
sqlite3_column_blob(s, 1), sqlite3_column_bytes(s, 1));
|
|
|
|
/* We expect only one row. We must execute another sqlite3_step()
|
|
* to complete the iteration; otherwise the table will remain locked. */
|
|
rc = sqlite3_step(s);
|
|
return rc==SQLITE_DONE ? SQLITE_OK : rc;
|
|
}
|
|
|
|
/* select max(first) from %_term where term = [zTerm] and first <= [iFirst]
|
|
* If found, returns SQLITE_ROW and result in *piResult; if the query returns
|
|
* NULL (meaning no row found) returns SQLITE_DONE.
|
|
*/
|
|
static int term_chunk_select(fulltext_vtab *v, const char *zTerm, int nTerm,
|
|
sqlite_int64 iFirst, sqlite_int64 *piResult){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, TERM_CHUNK_SELECT_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_text(s, 1, zTerm, nTerm, SQLITE_STATIC);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 2, iFirst);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sql_step_statement(v, TERM_CHUNK_SELECT_STMT, &s);
|
|
if( rc!=SQLITE_ROW ) return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
|
|
|
|
switch( sqlite3_column_type(s, 0) ){
|
|
case SQLITE_NULL:
|
|
rc = SQLITE_DONE;
|
|
break;
|
|
case SQLITE_INTEGER:
|
|
*piResult = sqlite3_column_int64(s, 0);
|
|
break;
|
|
default:
|
|
return SQLITE_ERROR;
|
|
}
|
|
/* We expect only one row. We must execute another sqlite3_step()
|
|
* to complete the iteration; otherwise the table will remain locked. */
|
|
if( sqlite3_step(s) != SQLITE_DONE ) return SQLITE_ERROR;
|
|
return rc;
|
|
}
|
|
|
|
/* insert into %_term (term, first, doclist)
|
|
values ([zTerm], [iFirst], [doclist]) */
|
|
static int term_insert(fulltext_vtab *v, const char *zTerm, int nTerm,
|
|
sqlite_int64 iFirst, DocList *doclist){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_text(s, 1, zTerm, nTerm, SQLITE_STATIC);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 2, iFirst);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_blob(s, 3, doclist->pData, doclist->nData, SQLITE_STATIC);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return sql_single_step_statement(v, TERM_INSERT_STMT, &s);
|
|
}
|
|
|
|
/* update %_term set doclist = [doclist] where rowid = [rowid] */
|
|
static int term_update(fulltext_vtab *v, sqlite_int64 rowid,
|
|
DocList *doclist){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, TERM_UPDATE_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_blob(s, 1, doclist->pData, doclist->nData,
|
|
SQLITE_STATIC);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 2, rowid);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return sql_single_step_statement(v, TERM_UPDATE_STMT, &s);
|
|
}
|
|
|
|
static int term_delete(fulltext_vtab *v, sqlite_int64 rowid){
|
|
sqlite3_stmt *s;
|
|
int rc = sql_get_statement(v, TERM_DELETE_STMT, &s);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_int64(s, 1, rowid);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return sql_single_step_statement(v, TERM_DELETE_STMT, &s);
|
|
}
|
|
|
|
static void fulltext_vtab_destroy(fulltext_vtab *v){
|
|
int iStmt;
|
|
|
|
for( iStmt=0; iStmt<MAX_STMT; iStmt++ ){
|
|
if( v->pFulltextStatements[iStmt]!=NULL ){
|
|
sqlite3_finalize(v->pFulltextStatements[iStmt]);
|
|
v->pFulltextStatements[iStmt] = NULL;
|
|
}
|
|
}
|
|
|
|
if( v->pTokenizer!=NULL ){
|
|
v->pTokenizer->pModule->xDestroy(v->pTokenizer);
|
|
v->pTokenizer = NULL;
|
|
}
|
|
|
|
free((void *) v->zName);
|
|
free(v);
|
|
}
|
|
|
|
/* Current interface:
|
|
** argv[0] - module name
|
|
** argv[1] - database name
|
|
** argv[2] - table name
|
|
** argv[3] - tokenizer name (optional, a sensible default is provided)
|
|
** argv[4..] - passed to tokenizer (optional based on tokenizer)
|
|
**/
|
|
static int fulltextConnect(
|
|
sqlite3 *db,
|
|
void *pAux,
|
|
int argc,
|
|
const char * const *argv,
|
|
sqlite3_vtab **ppVTab,
|
|
char **pzErr
|
|
){
|
|
int rc;
|
|
fulltext_vtab *v;
|
|
sqlite3_tokenizer_module *m = NULL;
|
|
|
|
assert( argc>=3 );
|
|
v = (fulltext_vtab *) malloc(sizeof(fulltext_vtab));
|
|
/* sqlite will initialize v->base */
|
|
v->db = db;
|
|
v->zName = string_dup(argv[2]);
|
|
v->pTokenizer = NULL;
|
|
|
|
if( argc==3 ){
|
|
get_simple_tokenizer_module(&m);
|
|
} else {
|
|
/* TODO(shess) For now, add new tokenizers as else if clauses. */
|
|
if( !strcmp(argv[3], "simple") ){
|
|
get_simple_tokenizer_module(&m);
|
|
} else {
|
|
assert( "unrecognized tokenizer"==NULL );
|
|
}
|
|
}
|
|
|
|
/* TODO(shess) Since tokenization impacts the index, the parameters
|
|
** to the tokenizer need to be identical when a persistent virtual
|
|
** table is re-created. One solution would be a meta-table to track
|
|
** such information in the database. Then we could verify that the
|
|
** information is identical on subsequent creates.
|
|
*/
|
|
/* TODO(shess) Why isn't argv already (const char **)? */
|
|
rc = m->xCreate(argc-3, (const char **) (argv+3), &v->pTokenizer);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
v->pTokenizer->pModule = m;
|
|
|
|
/* TODO: verify the existence of backing tables foo_content, foo_term */
|
|
|
|
rc = sqlite3_declare_vtab(db, "create table x(content text)");
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
memset(v->pFulltextStatements, 0, sizeof(v->pFulltextStatements));
|
|
|
|
*ppVTab = &v->base;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextCreate(
|
|
sqlite3 *db,
|
|
void *pAux,
|
|
int argc,
|
|
const char * const *argv,
|
|
sqlite3_vtab **ppVTab,
|
|
char **pzErr
|
|
){
|
|
int rc;
|
|
assert( argc>=3 );
|
|
|
|
/* The %_content table holds the text of each full-text item, with
|
|
** the rowid used as the docid.
|
|
**
|
|
** The %_term table maps each term to a document list blob
|
|
** containing elements sorted by ascending docid, each element
|
|
** encoded as:
|
|
**
|
|
** docid varint-encoded
|
|
** token count varint-encoded
|
|
** "count" token elements (poslist):
|
|
** position varint-encoded as delta from previous position
|
|
** start offset varint-encoded as delta from previous start offset
|
|
** end offset varint-encoded as delta from start offset
|
|
**
|
|
** Additionally, doclist blobs can be chunked into multiple rows,
|
|
** using "first" to order the blobs. "first" is simply the first
|
|
** docid in the blob.
|
|
*/
|
|
/*
|
|
** NOTE(shess) That last sentence is incorrect in the face of
|
|
** deletion, which can leave a doclist that doesn't contain the
|
|
** first from that row. I _believe_ this does not matter to the
|
|
** operation of the system, but it might be reasonable to update
|
|
** appropriately in case this assumption becomes more important.
|
|
*/
|
|
rc = sql_exec(db, argv[2],
|
|
"create table %_content(content text);"
|
|
"create table %_term(term text, first integer, doclist blob);"
|
|
"create index %_index on %_term(term, first)");
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return fulltextConnect(db, pAux, argc, argv, ppVTab, pzErr);
|
|
}
|
|
|
|
/* Decide how to handle an SQL query.
|
|
* At the moment, MATCH queries can include implicit boolean ANDs; we
|
|
* haven't implemented phrase searches or OR yet. */
|
|
static int fulltextBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
|
|
int i;
|
|
|
|
for(i=0; i<pInfo->nConstraint; ++i){
|
|
const struct sqlite3_index_constraint *pConstraint;
|
|
pConstraint = &pInfo->aConstraint[i];
|
|
if( pConstraint->iColumn==0 &&
|
|
pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH &&
|
|
pConstraint->usable ){ /* a full-text search */
|
|
pInfo->aConstraintUsage[i].argvIndex = 1;
|
|
pInfo->aConstraintUsage[i].omit = 1;
|
|
pInfo->idxNum = QUERY_FULLTEXT;
|
|
pInfo->estimatedCost = 1.0; /* an arbitrary value for now */
|
|
return SQLITE_OK;
|
|
}
|
|
}
|
|
pInfo->idxNum = QUERY_GENERIC;
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextDisconnect(sqlite3_vtab *pVTab){
|
|
fulltext_vtab_destroy((fulltext_vtab *)pVTab);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextDestroy(sqlite3_vtab *pVTab){
|
|
fulltext_vtab *v = (fulltext_vtab *)pVTab;
|
|
|
|
int rc = sql_exec(v->db, v->zName,
|
|
"drop table %_content; drop table %_term");
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
fulltext_vtab_destroy((fulltext_vtab *)pVTab);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
|
|
fulltext_cursor *c;
|
|
|
|
c = (fulltext_cursor *) calloc(sizeof(fulltext_cursor), 1);
|
|
/* sqlite will initialize c->base */
|
|
*ppCursor = &c->base;
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextClose(sqlite3_vtab_cursor *pCursor){
|
|
fulltext_cursor *c = (fulltext_cursor *) pCursor;
|
|
sqlite3_finalize(c->pStmt);
|
|
if( c->result.pDoclist!=NULL ){
|
|
docListDelete(c->result.pDoclist);
|
|
}
|
|
free(c);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextNext(sqlite3_vtab_cursor *pCursor){
|
|
fulltext_cursor *c = (fulltext_cursor *) pCursor;
|
|
sqlite_int64 iDocid;
|
|
int rc;
|
|
|
|
switch( c->iCursorType ){
|
|
case QUERY_GENERIC:
|
|
/* TODO(shess) Handle SQLITE_SCHEMA AND SQLITE_BUSY. */
|
|
rc = sqlite3_step(c->pStmt);
|
|
switch( rc ){
|
|
case SQLITE_ROW:
|
|
c->eof = 0;
|
|
return SQLITE_OK;
|
|
case SQLITE_DONE:
|
|
c->eof = 1;
|
|
return SQLITE_OK;
|
|
default:
|
|
c->eof = 1;
|
|
return rc;
|
|
}
|
|
case QUERY_FULLTEXT:
|
|
rc = sqlite3_reset(c->pStmt);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
if( readerAtEnd(&c->result)){
|
|
c->eof = 1;
|
|
return SQLITE_OK;
|
|
}
|
|
iDocid = readDocid(&c->result);
|
|
rc = sqlite3_bind_int64(c->pStmt, 1, iDocid);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
/* TODO(shess) Handle SQLITE_SCHEMA AND SQLITE_BUSY. */
|
|
rc = sqlite3_step(c->pStmt);
|
|
if( rc==SQLITE_ROW ){ /* the case we expect */
|
|
c->eof = 0;
|
|
return SQLITE_OK;
|
|
}
|
|
/* an error occurred; abort */
|
|
return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
|
|
default:
|
|
assert( 0 );
|
|
return SQLITE_ERROR; /* not reached */
|
|
}
|
|
}
|
|
|
|
static int term_select_doclist(fulltext_vtab *v, const char *pTerm, int nTerm,
|
|
sqlite3_stmt **ppStmt){
|
|
int rc;
|
|
if( *ppStmt ){
|
|
rc = sqlite3_reset(*ppStmt);
|
|
} else {
|
|
rc = sql_prepare(v->db, v->zName, ppStmt,
|
|
"select doclist from %_term where term = ? order by first");
|
|
}
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = sqlite3_bind_text(*ppStmt, 1, pTerm, nTerm, SQLITE_TRANSIENT);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return sqlite3_step(*ppStmt); /* TODO(adamd): handle schema error */
|
|
}
|
|
|
|
/* Read the posting list for [zTerm]; AND it with the doclist [in] to
|
|
* produce the doclist [out], using the given offset [iOffset] for phrase
|
|
* matching.
|
|
* (*pSelect) is used to hold an SQLite statement used inside this function;
|
|
* the caller should initialize *pSelect to NULL before the first call.
|
|
*/
|
|
static int query_merge(fulltext_vtab *v, sqlite3_stmt **pSelect,
|
|
const char *zTerm,
|
|
DocList *pIn, int iOffset, DocList *out){
|
|
int rc;
|
|
DocListMerge merge;
|
|
|
|
if( pIn!=NULL && !pIn->nData ){
|
|
/* If [pIn] is already empty, there's no point in reading the
|
|
* posting list to AND it in; return immediately. */
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
rc = term_select_doclist(v, zTerm, -1, pSelect);
|
|
if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ) return rc;
|
|
|
|
mergeInit(&merge, pIn, iOffset, out);
|
|
while( rc==SQLITE_ROW ){
|
|
DocList block;
|
|
docListInit(&block, DL_POSITIONS_OFFSETS,
|
|
sqlite3_column_blob(*pSelect, 0),
|
|
sqlite3_column_bytes(*pSelect, 0));
|
|
mergeBlock(&merge, &block);
|
|
docListDestroy(&block);
|
|
|
|
rc = sqlite3_step(*pSelect);
|
|
if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
|
|
return rc;
|
|
}
|
|
}
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
typedef struct QueryTerm {
|
|
int is_phrase; /* true if this term begins a new phrase */
|
|
const char *zTerm;
|
|
} QueryTerm;
|
|
|
|
/* A parsed query.
|
|
*
|
|
* As an example, parsing the query ["four score" years "new nation"] will
|
|
* yield a Query with 5 terms:
|
|
* "four", is_phrase = 1
|
|
* "score", is_phrase = 0
|
|
* "years", is_phrase = 1
|
|
* "new", is_phrase = 1
|
|
* "nation", is_phrase = 0
|
|
*/
|
|
typedef struct Query {
|
|
int nTerms;
|
|
QueryTerm *pTerm;
|
|
} Query;
|
|
|
|
static void query_add(Query *q, int is_phrase, const char *zTerm){
|
|
QueryTerm *t;
|
|
++q->nTerms;
|
|
q->pTerm = realloc(q->pTerm, q->nTerms * sizeof(q->pTerm[0]));
|
|
t = &q->pTerm[q->nTerms - 1];
|
|
t->is_phrase = is_phrase;
|
|
t->zTerm = zTerm;
|
|
}
|
|
|
|
static void query_free(Query *q){
|
|
int i;
|
|
for(i = 0; i < q->nTerms; ++i){
|
|
free((void *) q->pTerm[i].zTerm);
|
|
}
|
|
free(q->pTerm);
|
|
}
|
|
|
|
static int tokenize_segment(sqlite3_tokenizer *pTokenizer,
|
|
const char *zQuery, int in_phrase,
|
|
Query *pQuery){
|
|
sqlite3_tokenizer_module *pModule = pTokenizer->pModule;
|
|
sqlite3_tokenizer_cursor *pCursor;
|
|
int is_first = 1;
|
|
|
|
int rc = pModule->xOpen(pTokenizer, zQuery, -1, &pCursor);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
pCursor->pTokenizer = pTokenizer;
|
|
|
|
while( 1 ){
|
|
const char *zToken;
|
|
int nToken, iStartOffset, iEndOffset, dummy_pos;
|
|
|
|
rc = pModule->xNext(pCursor,
|
|
&zToken, &nToken,
|
|
&iStartOffset, &iEndOffset,
|
|
&dummy_pos);
|
|
if( rc!=SQLITE_OK ) break;
|
|
query_add(pQuery, !in_phrase || is_first, string_dup_n(zToken, nToken));
|
|
is_first = 0;
|
|
}
|
|
|
|
return pModule->xClose(pCursor);
|
|
}
|
|
|
|
/* Parse a query string, yielding a Query object. */
|
|
static int parse_query(fulltext_vtab *v, const char *zQuery, Query *pQuery){
|
|
char *zQuery1 = string_dup(zQuery);
|
|
int in_phrase = 0;
|
|
char *s = zQuery1;
|
|
pQuery->nTerms = 0;
|
|
pQuery->pTerm = NULL;
|
|
|
|
while( *s ){
|
|
char *t = s;
|
|
while( *t ){
|
|
if( *t=='"' ){
|
|
*t++ = '\0';
|
|
break;
|
|
}
|
|
++t;
|
|
}
|
|
if( *s ){
|
|
tokenize_segment(v->pTokenizer, s, in_phrase, pQuery);
|
|
}
|
|
s = t;
|
|
in_phrase = !in_phrase;
|
|
}
|
|
|
|
free(zQuery1);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* Perform a full-text query; return a list of documents in [pResult]. */
|
|
static int fulltext_query(fulltext_vtab *v, const char *zQuery,
|
|
DocList **pResult){
|
|
Query q;
|
|
int phrase_start = -1;
|
|
int i;
|
|
sqlite3_stmt *pSelect = NULL;
|
|
DocList *d = NULL;
|
|
|
|
int rc = parse_query(v, zQuery, &q);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
/* Merge terms. */
|
|
for(i = 0 ; i < q.nTerms ; ++i){
|
|
/* In each merge step, we need to generate positions whenever we're
|
|
* processing a phrase which hasn't ended yet. */
|
|
int need_positions = i<q.nTerms-1 && !q.pTerm[i+1].is_phrase;
|
|
DocList *next = docListNew(need_positions ? DL_POSITIONS : DL_DOCIDS);
|
|
if( q.pTerm[i].is_phrase ){
|
|
phrase_start = i;
|
|
}
|
|
rc = query_merge(v, &pSelect, q.pTerm[i].zTerm, d, i - phrase_start, next);
|
|
if( rc!=SQLITE_OK ) break;
|
|
if( d!=NULL ){
|
|
docListDelete(d);
|
|
}
|
|
d = next;
|
|
}
|
|
|
|
sqlite3_finalize(pSelect);
|
|
query_free(&q);
|
|
*pResult = d;
|
|
return rc;
|
|
}
|
|
|
|
static int fulltextFilter(sqlite3_vtab_cursor *pCursor,
|
|
int idxNum, const char *idxStr,
|
|
int argc, sqlite3_value **argv){
|
|
fulltext_cursor *c = (fulltext_cursor *) pCursor;
|
|
fulltext_vtab *v = cursor_vtab(c);
|
|
int rc;
|
|
const char *zStatement;
|
|
|
|
c->iCursorType = idxNum;
|
|
switch( idxNum ){
|
|
case QUERY_GENERIC:
|
|
zStatement = "select rowid, content from %_content";
|
|
break;
|
|
|
|
case QUERY_FULLTEXT: /* full-text search */
|
|
{
|
|
const char *zQuery = (const char *)sqlite3_value_text(argv[0]);
|
|
DocList *pResult;
|
|
assert( argc==1 );
|
|
rc = fulltext_query(v, zQuery, &pResult);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
readerInit(&c->result, pResult);
|
|
zStatement = "select rowid, content from %_content where rowid = ?";
|
|
break;
|
|
}
|
|
|
|
default:
|
|
assert( 0 );
|
|
}
|
|
|
|
rc = sql_prepare(v->db, v->zName, &c->pStmt, zStatement);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
return fulltextNext(pCursor);
|
|
}
|
|
|
|
static int fulltextEof(sqlite3_vtab_cursor *pCursor){
|
|
fulltext_cursor *c = (fulltext_cursor *) pCursor;
|
|
return c->eof;
|
|
}
|
|
|
|
static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
|
|
sqlite3_context *pContext, int idxCol){
|
|
fulltext_cursor *c = (fulltext_cursor *) pCursor;
|
|
const char *s;
|
|
|
|
assert( idxCol==0 );
|
|
s = (const char *) sqlite3_column_text(c->pStmt, 1);
|
|
sqlite3_result_text(pContext, s, -1, SQLITE_TRANSIENT);
|
|
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
static int fulltextRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
|
|
fulltext_cursor *c = (fulltext_cursor *) pCursor;
|
|
|
|
*pRowid = sqlite3_column_int64(c->pStmt, 0);
|
|
return SQLITE_OK;
|
|
}
|
|
|
|
/* Build a hash table containing all terms in zText. */
|
|
static int build_terms(Hash *terms, sqlite3_tokenizer *pTokenizer,
|
|
const char *zText, sqlite_int64 iDocid){
|
|
sqlite3_tokenizer_cursor *pCursor;
|
|
const char *pToken;
|
|
int nTokenBytes;
|
|
int iStartOffset, iEndOffset, iPosition;
|
|
|
|
int rc = pTokenizer->pModule->xOpen(pTokenizer, zText, -1, &pCursor);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
pCursor->pTokenizer = pTokenizer;
|
|
HashInit(terms, HASH_STRING, 1);
|
|
while( SQLITE_OK==pTokenizer->pModule->xNext(pCursor,
|
|
&pToken, &nTokenBytes,
|
|
&iStartOffset, &iEndOffset,
|
|
&iPosition) ){
|
|
DocList *p;
|
|
|
|
/* Positions can't be negative; we use -1 as a terminator internally. */
|
|
if( iPosition<0 ) {
|
|
rc = SQLITE_ERROR;
|
|
goto err;
|
|
}
|
|
|
|
p = HashFind(terms, pToken, nTokenBytes);
|
|
if( p==NULL ){
|
|
p = docListNew(DL_POSITIONS_OFFSETS);
|
|
docListAddDocid(p, iDocid);
|
|
HashInsert(terms, pToken, nTokenBytes, p);
|
|
}
|
|
docListAddPosOffset(p, iPosition, iStartOffset, iEndOffset);
|
|
}
|
|
|
|
err:
|
|
/* TODO(shess) Check return? Should this be able to cause errors at
|
|
** this point? Actually, same question about sqlite3_finalize(),
|
|
** though one could argue that failure there means that the data is
|
|
** not durable. *ponder*
|
|
*/
|
|
pTokenizer->pModule->xClose(pCursor);
|
|
return rc;
|
|
}
|
|
/* Update the %_terms table to map the term [zTerm] to the given rowid. */
|
|
static int index_insert_term(fulltext_vtab *v, const char *zTerm, int nTerm,
|
|
sqlite_int64 iDocid, DocList *p){
|
|
sqlite_int64 iFirst;
|
|
sqlite_int64 iIndexRow;
|
|
DocList doclist;
|
|
|
|
int rc = term_chunk_select(v, zTerm, nTerm, iDocid, &iFirst);
|
|
if( rc==SQLITE_DONE ){
|
|
docListInit(&doclist, DL_POSITIONS_OFFSETS, 0, 0);
|
|
if( docListUpdate(&doclist, iDocid, p) ){
|
|
rc = term_insert(v, zTerm, nTerm, iDocid, &doclist);
|
|
docListDestroy(&doclist);
|
|
return rc;
|
|
}
|
|
return SQLITE_OK;
|
|
}
|
|
if( rc!=SQLITE_ROW ) return SQLITE_ERROR;
|
|
|
|
/* This word is in the index; add this document ID to its blob. */
|
|
|
|
rc = term_select(v, zTerm, nTerm, iFirst, &iIndexRow, &doclist);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
if( docListUpdate(&doclist, iDocid, p) ){
|
|
/* If the blob is too big, split it in half. */
|
|
if( doclist.nData>CHUNK_MAX ){
|
|
DocList half;
|
|
if( docListSplit(&doclist, &half) ){
|
|
rc = term_insert(v, zTerm, nTerm, firstDocid(&half), &half);
|
|
docListDestroy(&half);
|
|
if( rc!=SQLITE_OK ) goto err;
|
|
}
|
|
}
|
|
rc = term_update(v, iIndexRow, &doclist);
|
|
}
|
|
|
|
err:
|
|
docListDestroy(&doclist);
|
|
return rc;
|
|
}
|
|
|
|
/* Insert a row into the full-text index; set *piRowid to be the ID of the
|
|
* new row. */
|
|
static int index_insert(fulltext_vtab *v,
|
|
sqlite3_value *pRequestRowid, const char *zText,
|
|
sqlite_int64 *piRowid){
|
|
Hash terms; /* maps term string -> PosList */
|
|
HashElem *e;
|
|
|
|
int rc = content_insert(v, pRequestRowid, zText, -1);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
*piRowid = sqlite3_last_insert_rowid(v->db);
|
|
|
|
if( !zText ) return SQLITE_OK; /* nothing to index */
|
|
|
|
rc = build_terms(&terms, v->pTokenizer, zText, *piRowid);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
for(e=HashFirst(&terms); e; e=HashNext(e)){
|
|
DocList *p = HashData(e);
|
|
rc = index_insert_term(v, HashKey(e), HashKeysize(e), *piRowid, p);
|
|
if( rc!=SQLITE_OK ) break;
|
|
}
|
|
|
|
for(e=HashFirst(&terms); e; e=HashNext(e)){
|
|
DocList *p = HashData(e);
|
|
docListDelete(p);
|
|
}
|
|
HashClear(&terms);
|
|
return rc;
|
|
}
|
|
|
|
static int index_delete_term(fulltext_vtab *v, const char *zTerm, int nTerm,
|
|
sqlite_int64 iDocid){
|
|
sqlite_int64 iFirst;
|
|
sqlite_int64 iIndexRow;
|
|
DocList doclist;
|
|
|
|
int rc = term_chunk_select(v, zTerm, nTerm, iDocid, &iFirst);
|
|
if( rc!=SQLITE_ROW ) return SQLITE_ERROR;
|
|
|
|
rc = term_select(v, zTerm, nTerm, iFirst, &iIndexRow, &doclist);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
if( docListUpdate(&doclist, iDocid, NULL) ){
|
|
if( doclist.nData>0 ){
|
|
rc = term_update(v, iIndexRow, &doclist);
|
|
} else { /* empty posting list */
|
|
rc = term_delete(v, iIndexRow);
|
|
}
|
|
}
|
|
docListDestroy(&doclist);
|
|
return rc;
|
|
}
|
|
|
|
/* Delete a row from the full-text index. */
|
|
static int index_delete(fulltext_vtab *v, sqlite_int64 iRow){
|
|
char *zText;
|
|
Hash terms;
|
|
HashElem *e;
|
|
|
|
int rc = content_select(v, iRow, &zText);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
rc = build_terms(&terms, v->pTokenizer, zText, iRow);
|
|
free(zText);
|
|
if( rc!=SQLITE_OK ) return rc;
|
|
|
|
for(e=HashFirst(&terms); e; e=HashNext(e)){
|
|
rc = index_delete_term(v, HashKey(e), HashKeysize(e), iRow);
|
|
if( rc!=SQLITE_OK ) break;
|
|
}
|
|
for(e=HashFirst(&terms); e; e=HashNext(e)){
|
|
DocList *p = HashData(e);
|
|
docListDelete(p);
|
|
}
|
|
HashClear(&terms);
|
|
|
|
return content_delete(v, iRow);
|
|
}
|
|
|
|
static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
|
|
sqlite_int64 *pRowid){
|
|
fulltext_vtab *v = (fulltext_vtab *) pVtab;
|
|
|
|
if( nArg<2 ){
|
|
return index_delete(v, sqlite3_value_int64(ppArg[0]));
|
|
}
|
|
|
|
if( sqlite3_value_type(ppArg[0]) != SQLITE_NULL ){
|
|
return SQLITE_ERROR; /* an update; not yet supported */
|
|
}
|
|
|
|
assert( nArg==3 ); /* ppArg[1] = rowid, ppArg[2] = content */
|
|
return index_insert(v, ppArg[1],
|
|
(const char *)sqlite3_value_text(ppArg[2]), pRowid);
|
|
}
|
|
|
|
static sqlite3_module fulltextModule = {
|
|
0,
|
|
fulltextCreate,
|
|
fulltextConnect,
|
|
fulltextBestIndex,
|
|
fulltextDisconnect,
|
|
fulltextDestroy,
|
|
fulltextOpen,
|
|
fulltextClose,
|
|
fulltextFilter,
|
|
fulltextNext,
|
|
fulltextEof,
|
|
fulltextColumn,
|
|
fulltextRowid,
|
|
fulltextUpdate
|
|
};
|
|
|
|
int fulltext_init(sqlite3 *db){
|
|
return sqlite3_create_module(db, "fulltext", &fulltextModule, 0);
|
|
}
|
|
|
|
#if !SQLITE_CORE
|
|
#ifdef _WIN32
|
|
__declspec(dllexport)
|
|
#endif
|
|
int sqlite3_fulltext_init(sqlite3 *db, char **pzErrMsg,
|
|
const sqlite3_api_routines *pApi){
|
|
SQLITE_EXTENSION_INIT2(pApi)
|
|
return fulltext_init(db);
|
|
}
|
|
#endif
|