blob: d5429ff320a9b7ebebcd6d2f18f3c9e3360735f7 [file] [log] [blame]
/* fts1 has a design flaw which can lead to database corruption (see
** below). It is recommended not to use it any longer, instead use
** fts3 (or higher). If you believe that your use of fts1 is safe,
** add -DSQLITE_ENABLE_BROKEN_FTS1=1 to your CFLAGS.
*/
#if (!defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)) \
&& !defined(SQLITE_ENABLE_BROKEN_FTS1)
#error fts1 has a design flaw and has been deprecated.
#endif
/* The flaw is that fts1 uses the content table's unaliased rowid as
** the unique docid. fts1 embeds the rowid in the index it builds,
** and expects the rowid to not change. The SQLite VACUUM operation
** will renumber such rowids, thereby breaking fts1. If you are using
** fts1 in a system which has disabled VACUUM, then you can continue
** to use it safely. Note that PRAGMA auto_vacuum does NOT disable
** VACUUM, though systems using auto_vacuum are unlikely to invoke
** VACUUM.
**
** fts1 should be safe even across VACUUM if you only insert documents
** and never delete.
*/
/* The author disclaims copyright to this source code.
*
* This is an SQLite module implementing full-text search.
*/
/*
** The code in this file is only compiled if:
**
** * The FTS1 module is being built as an extension
** (in which case SQLITE_CORE is not defined), or
**
** * The FTS1 module is being built into the core of
** SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)
#if defined(SQLITE_ENABLE_FTS1) && !defined(SQLITE_CORE)
# define SQLITE_CORE 1
#endif
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "fts1.h"
#include "fts1_hash.h"
#include "fts1_tokenizer.h"
#include "sqlite3.h"
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
#if 0
# define TRACE(A) printf A; fflush(stdout)
#else
# define TRACE(A)
#endif
/* utility functions */
typedef struct StringBuffer {
int len; /* length, not including null terminator */
int alloced; /* Space allocated for s[] */
char *s; /* Content of the string */
} StringBuffer;
static void initStringBuffer(StringBuffer *sb){
sb->len = 0;
sb->alloced = 100;
sb->s = malloc(100);
sb->s[0] = '\0';
}
static void nappend(StringBuffer *sb, const char *zFrom, int nFrom){
if( sb->len + nFrom >= sb->alloced ){
sb->alloced = sb->len + nFrom + 100;
sb->s = realloc(sb->s, sb->alloced+1);
if( sb->s==0 ){
initStringBuffer(sb);
return;
}
}
memcpy(sb->s + sb->len, zFrom, nFrom);
sb->len += nFrom;
sb->s[sb->len] = 0;
}
static void append(StringBuffer *sb, const char *zFrom){
nappend(sb, zFrom, strlen(zFrom));
}
/* We encode variable-length integers in little-endian order using seven bits
* per byte as follows:
**
** KEY:
** A = 0xxxxxxx 7 bits of data and one flag bit
** B = 1xxxxxxx 7 bits of data and one flag bit
**
** 7 bits - A
** 14 bits - BA
** 21 bits - BBA
** and so on.
*/
/* We may need up to VARINT_MAX bytes to store an encoded 64-bit integer. */
#define VARINT_MAX 10
/* Write a 64-bit variable-length integer to memory starting at p[0].
* The length of data written will be between 1 and VARINT_MAX bytes.
* The number of bytes written is returned. */
static int putVarint(char *p, sqlite_int64 v){
unsigned char *q = (unsigned char *) p;
sqlite_uint64 vu = v;
do{
*q++ = (unsigned char) ((vu & 0x7f) | 0x80);
vu >>= 7;
}while( vu!=0 );
q[-1] &= 0x7f; /* turn off high bit in final byte */
assert( q - (unsigned char *)p <= VARINT_MAX );
return (int) (q - (unsigned char *)p);
}
/* Read a 64-bit variable-length integer from memory starting at p[0].
* Return the number of bytes read, or 0 on error.
* The value is stored in *v. */
static int getVarint(const char *p, sqlite_int64 *v){
const unsigned char *q = (const unsigned char *) p;
sqlite_uint64 x = 0, y = 1;
while( (*q & 0x80) == 0x80 ){
x += y * (*q++ & 0x7f);
y <<= 7;
if( q - (unsigned char *)p >= VARINT_MAX ){ /* bad data */
assert( 0 );
return 0;
}
}
x += y * (*q++);
*v = (sqlite_int64) x;
return (int) (q - (unsigned char *)p);
}
static int getVarint32(const char *p, int *pi){
sqlite_int64 i;
int ret = getVarint(p, &i);
*pi = (int) i;
assert( *pi==i );
return ret;
}
/*** Document lists ***
*
* A document list holds a sorted list of varint-encoded document IDs.
*
* A doclist with type DL_POSITIONS_OFFSETS is stored like this:
*
* array {
* varint docid;
* array {
* varint position; (delta from previous position plus POS_BASE)
* varint startOffset; (delta from previous startOffset)
* varint endOffset; (delta from startOffset)
* }
* }
*
* Here, array { X } means zero or more occurrences of X, adjacent in memory.
*
* A position list may hold positions for text in multiple columns. A position
* POS_COLUMN is followed by a varint containing the index of the column for
* following positions in the list. Any positions appearing before any
* occurrences of POS_COLUMN are for column 0.
*
* A doclist with type DL_POSITIONS is like the above, but holds only docids
* and positions without offset information.
*
* A doclist with type DL_DOCIDS is like the above, but holds only docids
* without positions or offset information.
*
* On disk, every document list has positions and offsets, so we don't bother
* to serialize a doclist's type.
*
* We don't yet delta-encode document IDs; doing so will probably be a
* modest win.
*
* NOTE(shess) I've thought of a slightly (1%) better offset encoding.
* After the first offset, estimate the next offset by using the
* current token position and the previous token position and offset,
* offset to handle some variance. So the estimate would be
* (iPosition*w->iStartOffset/w->iPosition-64), which is delta-encoded
* as normal. Offsets more than 64 chars from the estimate are
* encoded as the delta to the previous start offset + 128. An
* additional tiny increment can be gained by using the end offset of
* the previous token to make the estimate a tiny bit more precise.
*/
/* It is not safe to call isspace(), tolower(), or isalnum() on
** hi-bit-set characters. This is the same solution used in the
** tokenizer.
*/
/* TODO(shess) The snippet-generation code should be using the
** tokenizer-generated tokens rather than doing its own local
** tokenization.
*/
/* TODO(shess) Is __isascii() a portable version of (c&0x80)==0? */
static int safe_isspace(char c){
return (c&0x80)==0 ? isspace(c) : 0;
}
static int safe_tolower(char c){
return (c&0x80)==0 ? tolower(c) : c;
}
static int safe_isalnum(char c){
return (c&0x80)==0 ? isalnum(c) : 0;
}
typedef enum DocListType {
DL_DOCIDS, /* docids only */
DL_POSITIONS, /* docids + positions */
DL_POSITIONS_OFFSETS /* docids + positions + offsets */
} DocListType;
/*
** By default, only positions and not offsets are stored in the doclists.
** To change this so that offsets are stored too, compile with
**
** -DDL_DEFAULT=DL_POSITIONS_OFFSETS
**
*/
#ifndef DL_DEFAULT
# define DL_DEFAULT DL_POSITIONS
#endif
typedef struct DocList {
char *pData;
int nData;
DocListType iType;
int iLastColumn; /* the last column written */
int iLastPos; /* the last position written */
int iLastOffset; /* the last start offset written */
} DocList;
enum {
POS_END = 0, /* end of this position list */
POS_COLUMN, /* followed by new column number */
POS_BASE
};
/* Initialize a new DocList to hold the given data. */
static void docListInit(DocList *d, DocListType iType,
const char *pData, int nData){
d->nData = nData;
if( nData>0 ){
d->pData = malloc(nData);
memcpy(d->pData, pData, nData);
} else {
d->pData = NULL;
}
d->iType = iType;
d->iLastColumn = 0;
d->iLastPos = d->iLastOffset = 0;
}
/* Create a new dynamically-allocated DocList. */
static DocList *docListNew(DocListType iType){
DocList *d = (DocList *) malloc(sizeof(DocList));
docListInit(d, iType, 0, 0);
return d;
}
static void docListDestroy(DocList *d){
free(d->pData);
#ifndef NDEBUG
memset(d, 0x55, sizeof(*d));
#endif
}
static void docListDelete(DocList *d){
docListDestroy(d);
free(d);
}
static char *docListEnd(DocList *d){
return d->pData + d->nData;
}
/* Append a varint to a DocList's data. */
static void appendVarint(DocList *d, sqlite_int64 i){
char c[VARINT_MAX];
int n = putVarint(c, i);
d->pData = realloc(d->pData, d->nData + n);
memcpy(d->pData + d->nData, c, n);
d->nData += n;
}
static void docListAddDocid(DocList *d, sqlite_int64 iDocid){
appendVarint(d, iDocid);
if( d->iType>=DL_POSITIONS ){
appendVarint(d, POS_END); /* initially empty position list */
d->iLastColumn = 0;
d->iLastPos = d->iLastOffset = 0;
}
}
/* helper function for docListAddPos and docListAddPosOffset */
static void addPos(DocList *d, int iColumn, int iPos){
assert( d->nData>0 );
--d->nData; /* remove previous terminator */
if( iColumn!=d->iLastColumn ){
assert( iColumn>d->iLastColumn );
appendVarint(d, POS_COLUMN);
appendVarint(d, iColumn);
d->iLastColumn = iColumn;
d->iLastPos = d->iLastOffset = 0;
}
assert( iPos>=d->iLastPos );
appendVarint(d, iPos-d->iLastPos+POS_BASE);
d->iLastPos = iPos;
}
/* Add a position to the last position list in a doclist. */
static void docListAddPos(DocList *d, int iColumn, int iPos){
assert( d->iType==DL_POSITIONS );
addPos(d, iColumn, iPos);
appendVarint(d, POS_END); /* add new terminator */
}
/*
** Add a position and starting and ending offsets to a doclist.
**
** If the doclist is setup to handle only positions, then insert
** the position only and ignore the offsets.
*/
static void docListAddPosOffset(
DocList *d, /* Doclist under construction */
int iColumn, /* Column the inserted term is part of */
int iPos, /* Position of the inserted term */
int iStartOffset, /* Starting offset of inserted term */
int iEndOffset /* Ending offset of inserted term */
){
assert( d->iType>=DL_POSITIONS );
addPos(d, iColumn, iPos);
if( d->iType==DL_POSITIONS_OFFSETS ){
assert( iStartOffset>=d->iLastOffset );
appendVarint(d, iStartOffset-d->iLastOffset);
d->iLastOffset = iStartOffset;
assert( iEndOffset>=iStartOffset );
appendVarint(d, iEndOffset-iStartOffset);
}
appendVarint(d, POS_END); /* add new terminator */
}
/*
** A DocListReader object is a cursor into a doclist. Initialize
** the cursor to the beginning of the doclist by calling readerInit().
** Then use routines
**
** peekDocid()
** readDocid()
** readPosition()
** skipPositionList()
** and so forth...
**
** to read information out of the doclist. When we reach the end
** of the doclist, atEnd() returns TRUE.
*/
typedef struct DocListReader {
DocList *pDoclist; /* The document list we are stepping through */
char *p; /* Pointer to next unread byte in the doclist */
int iLastColumn;
int iLastPos; /* the last position read, or -1 when not in a position list */
} DocListReader;
/*
** Initialize the DocListReader r to point to the beginning of pDoclist.
*/
static void readerInit(DocListReader *r, DocList *pDoclist){
r->pDoclist = pDoclist;
if( pDoclist!=NULL ){
r->p = pDoclist->pData;
}
r->iLastColumn = -1;
r->iLastPos = -1;
}
/*
** Return TRUE if we have reached then end of pReader and there is
** nothing else left to read.
*/
static int atEnd(DocListReader *pReader){
return pReader->pDoclist==0 || (pReader->p >= docListEnd(pReader->pDoclist));
}
/* Peek at the next docid without advancing the read pointer.
*/
static sqlite_int64 peekDocid(DocListReader *pReader){
sqlite_int64 ret;
assert( !atEnd(pReader) );
assert( pReader->iLastPos==-1 );
getVarint(pReader->p, &ret);
return ret;
}
/* Read the next docid. See also nextDocid().
*/
static sqlite_int64 readDocid(DocListReader *pReader){
sqlite_int64 ret;
assert( !atEnd(pReader) );
assert( pReader->iLastPos==-1 );
pReader->p += getVarint(pReader->p, &ret);
if( pReader->pDoclist->iType>=DL_POSITIONS ){
pReader->iLastColumn = 0;
pReader->iLastPos = 0;
}
return ret;
}
/* Read the next position and column index from a position list.
* Returns the position, or -1 at the end of the list. */
static int readPosition(DocListReader *pReader, int *iColumn){
int i;
int iType = pReader->pDoclist->iType;
if( pReader->iLastPos==-1 ){
return -1;
}
assert( !atEnd(pReader) );
if( iType<DL_POSITIONS ){
return -1;
}
pReader->p += getVarint32(pReader->p, &i);
if( i==POS_END ){
pReader->iLastColumn = pReader->iLastPos = -1;
*iColumn = -1;
return -1;
}
if( i==POS_COLUMN ){
pReader->p += getVarint32(pReader->p, &pReader->iLastColumn);
pReader->iLastPos = 0;
pReader->p += getVarint32(pReader->p, &i);
assert( i>=POS_BASE );
}
pReader->iLastPos += ((int) i)-POS_BASE;
if( iType>=DL_POSITIONS_OFFSETS ){
/* Skip over offsets, ignoring them for now. */
int iStart, iEnd;
pReader->p += getVarint32(pReader->p, &iStart);
pReader->p += getVarint32(pReader->p, &iEnd);
}
*iColumn = pReader->iLastColumn;
return pReader->iLastPos;
}
/* Skip past the end of a position list. */
static void skipPositionList(DocListReader *pReader){
DocList *p = pReader->pDoclist;
if( p && p->iType>=DL_POSITIONS ){
int iColumn;
while( readPosition(pReader, &iColumn)!=-1 ){}
}
}
/* Skip over a docid, including its position list if the doclist has
* positions. */
static void skipDocument(DocListReader *pReader){
readDocid(pReader);
skipPositionList(pReader);
}
/* Skip past all docids which are less than [iDocid]. Returns 1 if a docid
* matching [iDocid] was found. */
static int skipToDocid(DocListReader *pReader, sqlite_int64 iDocid){
sqlite_int64 d = 0;
while( !atEnd(pReader) && (d=peekDocid(pReader))<iDocid ){
skipDocument(pReader);
}
return !atEnd(pReader) && d==iDocid;
}
/* Return the first document in a document list.
*/
static sqlite_int64 firstDocid(DocList *d){
DocListReader r;
readerInit(&r, d);
return readDocid(&r);
}
#ifdef SQLITE_DEBUG
/*
** This routine is used for debugging purpose only.
**
** Write the content of a doclist to standard output.
*/
static void printDoclist(DocList *p){
DocListReader r;
const char *zSep = "";
readerInit(&r, p);
while( !atEnd(&r) ){
sqlite_int64 docid = readDocid(&r);
if( docid==0 ){
skipPositionList(&r);
continue;
}
printf("%s%lld", zSep, docid);
zSep = ",";
if( p->iType>=DL_POSITIONS ){
int iPos, iCol;
const char *zDiv = "";
printf("(");
while( (iPos = readPosition(&r, &iCol))>=0 ){
printf("%s%d:%d", zDiv, iCol, iPos);
zDiv = ":";
}
printf(")");
}
}
printf("\n");
fflush(stdout);
}
#endif /* SQLITE_DEBUG */
/* Trim the given doclist to contain only positions in column
* [iRestrictColumn]. */
static void docListRestrictColumn(DocList *in, int iRestrictColumn){
DocListReader r;
DocList out;
assert( in->iType>=DL_POSITIONS );
readerInit(&r, in);
docListInit(&out, DL_POSITIONS, NULL, 0);
while( !atEnd(&r) ){
sqlite_int64 iDocid = readDocid(&r);
int iPos, iColumn;
docListAddDocid(&out, iDocid);
while( (iPos = readPosition(&r, &iColumn)) != -1 ){
if( iColumn==iRestrictColumn ){
docListAddPos(&out, iColumn, iPos);
}
}
}
docListDestroy(in);
*in = out;
}
/* Trim the given doclist by discarding any docids without any remaining
* positions. */
static void docListDiscardEmpty(DocList *in) {
DocListReader r;
DocList out;
/* TODO: It would be nice to implement this operation in place; that
* could save a significant amount of memory in queries with long doclists. */
assert( in->iType>=DL_POSITIONS );
readerInit(&r, in);
docListInit(&out, DL_POSITIONS, NULL, 0);
while( !atEnd(&r) ){
sqlite_int64 iDocid = readDocid(&r);
int match = 0;
int iPos, iColumn;
while( (iPos = readPosition(&r, &iColumn)) != -1 ){
if( !match ){
docListAddDocid(&out, iDocid);
match = 1;
}
docListAddPos(&out, iColumn, iPos);
}
}
docListDestroy(in);
*in = out;
}
/* Helper function for docListUpdate() and docListAccumulate().
** Splices a doclist element into the doclist represented by r,
** leaving r pointing after the newly spliced element.
*/
static void docListSpliceElement(DocListReader *r, sqlite_int64 iDocid,
const char *pSource, int nSource){
DocList *d = r->pDoclist;
char *pTarget;
int nTarget, found;
found = skipToDocid(r, iDocid);
/* Describe slice in d to place pSource/nSource. */
pTarget = r->p;
if( found ){
skipDocument(r);
nTarget = r->p-pTarget;
}else{
nTarget = 0;
}
/* The sense of the following is that there are three possibilities.
** If nTarget==nSource, we should not move any memory nor realloc.
** If nTarget>nSource, trim target and realloc.
** If nTarget<nSource, realloc then expand target.
*/
if( nTarget>nSource ){
memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));
}
if( nTarget!=nSource ){
int iDoclist = pTarget-d->pData;
d->pData = realloc(d->pData, d->nData+nSource-nTarget);
pTarget = d->pData+iDoclist;
}
if( nTarget<nSource ){
memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));
}
memcpy(pTarget, pSource, nSource);
d->nData += nSource-nTarget;
r->p = pTarget+nSource;
}
/* Insert/update pUpdate into the doclist. */
static void docListUpdate(DocList *d, DocList *pUpdate){
DocListReader reader;
assert( d!=NULL && pUpdate!=NULL );
assert( d->iType==pUpdate->iType);
readerInit(&reader, d);
docListSpliceElement(&reader, firstDocid(pUpdate),
pUpdate->pData, pUpdate->nData);
}
/* Propagate elements from pUpdate to pAcc, overwriting elements with
** matching docids.
*/
static void docListAccumulate(DocList *pAcc, DocList *pUpdate){
DocListReader accReader, updateReader;
/* Handle edge cases where one doclist is empty. */
assert( pAcc!=NULL );
if( pUpdate==NULL || pUpdate->nData==0 ) return;
if( pAcc->nData==0 ){
pAcc->pData = malloc(pUpdate->nData);
memcpy(pAcc->pData, pUpdate->pData, pUpdate->nData);
pAcc->nData = pUpdate->nData;
return;
}
readerInit(&accReader, pAcc);
readerInit(&updateReader, pUpdate);
while( !atEnd(&updateReader) ){
char *pSource = updateReader.p;
sqlite_int64 iDocid = readDocid(&updateReader);
skipPositionList(&updateReader);
docListSpliceElement(&accReader, iDocid, pSource, updateReader.p-pSource);
}
}
/*
** Read the next docid off of pIn. Return 0 if we reach the end.
*
* TODO: This assumes that docids are never 0, but they may actually be 0 since
* users can choose docids when inserting into a full-text table. Fix this.
*/
static sqlite_int64 nextDocid(DocListReader *pIn){
skipPositionList(pIn);
return atEnd(pIn) ? 0 : readDocid(pIn);
}
/*
** pLeft and pRight are two DocListReaders that are pointing to
** positions lists of the same document: iDocid.
**
** If there are no instances in pLeft or pRight where the position
** of pLeft is one less than the position of pRight, then this
** routine adds nothing to pOut.
**
** If there are one or more instances where positions from pLeft
** are exactly one less than positions from pRight, then add a new
** document record to pOut. If pOut wants to hold positions, then
** include the positions from pRight that are one more than a
** position in pLeft. In other words: pRight.iPos==pLeft.iPos+1.
**
** pLeft and pRight are left pointing at the next document record.
*/
static void mergePosList(
DocListReader *pLeft, /* Left position list */
DocListReader *pRight, /* Right position list */
sqlite_int64 iDocid, /* The docid from pLeft and pRight */
DocList *pOut /* Write the merged document record here */
){
int iLeftCol, iLeftPos = readPosition(pLeft, &iLeftCol);
int iRightCol, iRightPos = readPosition(pRight, &iRightCol);
int match = 0;
/* Loop until we've reached the end of both position lists. */
while( iLeftPos!=-1 && iRightPos!=-1 ){
if( iLeftCol==iRightCol && iLeftPos+1==iRightPos ){
if( !match ){
docListAddDocid(pOut, iDocid);
match = 1;
}
if( pOut->iType>=DL_POSITIONS ){
docListAddPos(pOut, iRightCol, iRightPos);
}
iLeftPos = readPosition(pLeft, &iLeftCol);
iRightPos = readPosition(pRight, &iRightCol);
}else if( iRightCol<iLeftCol ||
(iRightCol==iLeftCol && iRightPos<iLeftPos+1) ){
iRightPos = readPosition(pRight, &iRightCol);
}else{
iLeftPos = readPosition(pLeft, &iLeftCol);
}
}
if( iLeftPos>=0 ) skipPositionList(pLeft);
if( iRightPos>=0 ) skipPositionList(pRight);
}
/* We have two doclists: pLeft and pRight.
** Write the phrase intersection of these two doclists into pOut.
**
** A phrase intersection means that two documents only match
** if pLeft.iPos+1==pRight.iPos.
**
** The output pOut may or may not contain positions. If pOut
** does contain positions, they are the positions of pRight.
*/
static void docListPhraseMerge(
DocList *pLeft, /* Doclist resulting from the words on the left */
DocList *pRight, /* Doclist for the next word to the right */
DocList *pOut /* Write the combined doclist here */
){
DocListReader left, right;
sqlite_int64 docidLeft, docidRight;
readerInit(&left, pLeft);
readerInit(&right, pRight);
docidLeft = nextDocid(&left);
docidRight = nextDocid(&right);
while( docidLeft>0 && docidRight>0 ){
if( docidLeft<docidRight ){
docidLeft = nextDocid(&left);
}else if( docidRight<docidLeft ){
docidRight = nextDocid(&right);
}else{
mergePosList(&left, &right, docidLeft, pOut);
docidLeft = nextDocid(&left);
docidRight = nextDocid(&right);
}
}
}
/* We have two doclists: pLeft and pRight.
** Write the intersection of these two doclists into pOut.
** Only docids are matched. Position information is ignored.
**
** The output pOut never holds positions.
*/
static void docListAndMerge(
DocList *pLeft, /* Doclist resulting from the words on the left */
DocList *pRight, /* Doclist for the next word to the right */
DocList *pOut /* Write the combined doclist here */
){
DocListReader left, right;
sqlite_int64 docidLeft, docidRight;
assert( pOut->iType<DL_POSITIONS );
readerInit(&left, pLeft);
readerInit(&right, pRight);
docidLeft = nextDocid(&left);
docidRight = nextDocid(&right);
while( docidLeft>0 && docidRight>0 ){
if( docidLeft<docidRight ){
docidLeft = nextDocid(&left);
}else if( docidRight<docidLeft ){
docidRight = nextDocid(&right);
}else{
docListAddDocid(pOut, docidLeft);
docidLeft = nextDocid(&left);
docidRight = nextDocid(&right);
}
}
}
/* We have two doclists: pLeft and pRight.
** Write the union of these two doclists into pOut.
** Only docids are matched. Position information is ignored.
**
** The output pOut never holds positions.
*/
static void docListOrMerge(
DocList *pLeft, /* Doclist resulting from the words on the left */
DocList *pRight, /* Doclist for the next word to the right */
DocList *pOut /* Write the combined doclist here */
){
DocListReader left, right;
sqlite_int64 docidLeft, docidRight, priorLeft;
readerInit(&left, pLeft);
readerInit(&right, pRight);
docidLeft = nextDocid(&left);
docidRight = nextDocid(&right);
while( docidLeft>0 && docidRight>0 ){
if( docidLeft<=docidRight ){
docListAddDocid(pOut, docidLeft);
}else{
docListAddDocid(pOut, docidRight);
}
priorLeft = docidLeft;
if( docidLeft<=docidRight ){
docidLeft = nextDocid(&left);
}
if( docidRight>0 && docidRight<=priorLeft ){
docidRight = nextDocid(&right);
}
}
while( docidLeft>0 ){
docListAddDocid(pOut, docidLeft);
docidLeft = nextDocid(&left);
}
while( docidRight>0 ){
docListAddDocid(pOut, docidRight);
docidRight = nextDocid(&right);
}
}
/* We have two doclists: pLeft and pRight.
** Write into pOut all documents that occur in pLeft but not
** in pRight.
**
** Only docids are matched. Position information is ignored.
**
** The output pOut never holds positions.
*/
static void docListExceptMerge(
DocList *pLeft, /* Doclist resulting from the words on the left */
DocList *pRight, /* Doclist for the next word to the right */
DocList *pOut /* Write the combined doclist here */
){
DocListReader left, right;
sqlite_int64 docidLeft, docidRight, priorLeft;
readerInit(&left, pLeft);
readerInit(&right, pRight);
docidLeft = nextDocid(&left);
docidRight = nextDocid(&right);
while( docidLeft>0 && docidRight>0 ){
priorLeft = docidLeft;
if( docidLeft<docidRight ){
docListAddDocid(pOut, docidLeft);
}
if( docidLeft<=docidRight ){
docidLeft = nextDocid(&left);
}
if( docidRight>0 && docidRight<=priorLeft ){
docidRight = nextDocid(&right);
}
}
while( docidLeft>0 ){
docListAddDocid(pOut, docidLeft);
docidLeft = nextDocid(&left);
}
}
static char *string_dup_n(const char *s, int n){
char *str = malloc(n + 1);
memcpy(str, s, n);
str[n] = '\0';
return str;
}
/* Duplicate a string; the caller must free() the returned string.
* (We don't use strdup() since it is not part of the standard C library and
* may not be available everywhere.) */
static char *string_dup(const char *s){
return string_dup_n(s, strlen(s));
}
/* Format a string, replacing each occurrence of the % character with
* zDb.zName. This may be more convenient than sqlite_mprintf()
* when one string is used repeatedly in a format string.
* The caller must free() the returned string. */
static char *string_format(const char *zFormat,
const char *zDb, const char *zName){
const char *p;
size_t len = 0;
size_t nDb = strlen(zDb);
size_t nName = strlen(zName);
size_t nFullTableName = nDb+1+nName;
char *result;
char *r;
/* first compute length needed */
for(p = zFormat ; *p ; ++p){
len += (*p=='%' ? nFullTableName : 1);
}
len += 1; /* for null terminator */
r = result = malloc(len);
for(p = zFormat; *p; ++p){
if( *p=='%' ){
memcpy(r, zDb, nDb);
r += nDb;
*r++ = '.';
memcpy(r, zName, nName);
r += nName;
} else {
*r++ = *p;
}
}
*r++ = '\0';
assert( r == result + len );
return result;
}
static int sql_exec(sqlite3 *db, const char *zDb, const char *zName,
const char *zFormat){
char *zCommand = string_format(zFormat, zDb, zName);
int rc;
TRACE(("FTS1 sql: %s\n", zCommand));
rc = sqlite3_exec(db, zCommand, NULL, 0, NULL);
free(zCommand);
return rc;
}
static int sql_prepare(sqlite3 *db, const char *zDb, const char *zName,
sqlite3_stmt **ppStmt, const char *zFormat){
char *zCommand = string_format(zFormat, zDb, zName);
int rc;
TRACE(("FTS1 prepare: %s\n", zCommand));
rc = sqlite3_prepare(db, zCommand, -1, ppStmt, NULL);
free(zCommand);
return rc;
}
/* end utility functions */
/* Forward reference */
typedef struct fulltext_vtab fulltext_vtab;
/* A single term in a query is represented by an instances of
** the following structure.
*/
typedef struct QueryTerm {
short int nPhrase; /* How many following terms are part of the same phrase */
short int iPhrase; /* This is the i-th term of a phrase. */
short int iColumn; /* Column of the index that must match this term */
signed char isOr; /* this term is preceded by "OR" */
signed char isNot; /* this term is preceded by "-" */
char *pTerm; /* text of the term. '\000' terminated. malloced */
int nTerm; /* Number of bytes in pTerm[] */
} QueryTerm;
/* A query string is parsed into a Query structure.
*
* We could, in theory, allow query strings to be complicated
* nested expressions with precedence determined by parentheses.
* But none of the major search engines do this. (Perhaps the
* feeling is that an parenthesized expression is two complex of
* an idea for the average user to grasp.) Taking our lead from
* the major search engines, we will allow queries to be a list
* of terms (with an implied AND operator) or phrases in double-quotes,
* with a single optional "-" before each non-phrase term to designate
* negation and an optional OR connector.
*
* OR binds more tightly than the implied AND, which is what the
* major search engines seem to do. So, for example:
*
* [one two OR three] ==> one AND (two OR three)
* [one OR two three] ==> (one OR two) AND three
*
* A "-" before a term matches all entries that lack that term.
* The "-" must occur immediately before the term with in intervening
* space. This is how the search engines do it.
*
* A NOT term cannot be the right-hand operand of an OR. If this
* occurs in the query string, the NOT is ignored:
*
* [one OR -two] ==> one OR two
*
*/
typedef struct Query {
fulltext_vtab *pFts; /* The full text index */
int nTerms; /* Number of terms in the query */
QueryTerm *pTerms; /* Array of terms. Space obtained from malloc() */
int nextIsOr; /* Set the isOr flag on the next inserted term */
int nextColumn; /* Next word parsed must be in this column */
int dfltColumn; /* The default column */
} Query;
/*
** An instance of the following structure keeps track of generated
** matching-word offset information and snippets.
*/
typedef struct Snippet {
int nMatch; /* Total number of matches */
int nAlloc; /* Space allocated for aMatch[] */
struct snippetMatch { /* One entry for each matching term */
char snStatus; /* Status flag for use while constructing snippets */
short int iCol; /* The column that contains the match */
short int iTerm; /* The index in Query.pTerms[] of the matching term */
short int nByte; /* Number of bytes in the term */
int iStart; /* The offset to the first character of the term */
} *aMatch; /* Points to space obtained from malloc */
char *zOffset; /* Text rendering of aMatch[] */
int nOffset; /* strlen(zOffset) */
char *zSnippet; /* Snippet text */
int nSnippet; /* strlen(zSnippet) */
} Snippet;
typedef enum QueryType {
QUERY_GENERIC, /* table scan */
QUERY_ROWID, /* lookup by rowid */
QUERY_FULLTEXT /* QUERY_FULLTEXT + [i] is a full-text search for column i*/
} QueryType;
/* TODO(shess) CHUNK_MAX controls how much data we allow in segment 0
** before we start aggregating into larger segments. Lower CHUNK_MAX
** means that for a given input we have more individual segments per
** term, which means more rows in the table and a bigger index (due to
** both more rows and bigger rowids). But it also reduces the average
** cost of adding new elements to the segment 0 doclist, and it seems
** to reduce the number of pages read and written during inserts. 256
** was chosen by measuring insertion times for a certain input (first
** 10k documents of Enron corpus), though including query performance
** in the decision may argue for a larger value.
*/
#define CHUNK_MAX 256
typedef enum fulltext_statement {
CONTENT_INSERT_STMT,
CONTENT_SELECT_STMT,
CONTENT_UPDATE_STMT,
CONTENT_DELETE_STMT,
TERM_SELECT_STMT,
TERM_SELECT_ALL_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 *const fulltext_zStatement[MAX_STMT] = {
/* CONTENT_INSERT */ NULL, /* generated in contentInsertStatement() */
/* CONTENT_SELECT */ "select * from %_content where rowid = ?",
/* CONTENT_UPDATE */ NULL, /* generated in contentUpdateStatement() */
/* CONTENT_DELETE */ "delete from %_content where rowid = ?",
/* TERM_SELECT */
"select rowid, doclist from %_term where term = ? and segment = ?",
/* TERM_SELECT_ALL */
"select doclist from %_term where term = ? order by segment",
/* TERM_INSERT */
"insert into %_term (rowid, term, segment, doclist) values (?, ?, ?, ?)",
/* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
/* TERM_DELETE */ "delete from %_term where rowid = ?",
};
/*
** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
*/
struct fulltext_vtab {
sqlite3_vtab base; /* Base class used by SQLite core */
sqlite3 *db; /* The database connection */
const char *zDb; /* logical database name */
const char *zName; /* virtual table name */
int nColumn; /* number of columns in virtual table */
char **azColumn; /* column names. malloced */
char **azContentColumn; /* column names in content table; malloced */
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];
};
/*
** When the core wants to do a query, it create a cursor using a
** call to xOpen. This structure is an instance of a cursor. It
** is destroyed by xClose.
*/
typedef struct fulltext_cursor {
sqlite3_vtab_cursor base; /* Base class used by SQLite core */
QueryType iCursorType; /* Copy of sqlite3_index_info.idxNum */
sqlite3_stmt *pStmt; /* Prepared statement in use by the cursor */
int eof; /* True if at End Of Results */
Query q; /* Parsed query string */
Snippet snippet; /* Cached snippet for the current row */
int iColumn; /* Column being searched */
DocListReader result; /* used when iCursorType == QUERY_FULLTEXT */
} fulltext_cursor;
static struct fulltext_vtab *cursor_vtab(fulltext_cursor *c){
return (fulltext_vtab *) c->base.pVtab;
}
static const sqlite3_module fulltextModule; /* forward declaration */
/* Append a list of strings separated by commas to a StringBuffer. */
static void appendList(StringBuffer *sb, int nString, char **azString){
int i;
for(i=0; i<nString; ++i){
if( i>0 ) append(sb, ", ");
append(sb, azString[i]);
}
}
/* Return a dynamically generated statement of the form
* insert into %_content (rowid, ...) values (?, ...)
*/
static const char *contentInsertStatement(fulltext_vtab *v){
StringBuffer sb;
int i;
initStringBuffer(&sb);
append(&sb, "insert into %_content (rowid, ");
appendList(&sb, v->nColumn, v->azContentColumn);
append(&sb, ") values (?");
for(i=0; i<v->nColumn; ++i)
append(&sb, ", ?");
append(&sb, ")");
return sb.s;
}
/* Return a dynamically generated statement of the form
* update %_content set [col_0] = ?, [col_1] = ?, ...
* where rowid = ?
*/
static const char *contentUpdateStatement(fulltext_vtab *v){
StringBuffer sb;
int i;
initStringBuffer(&sb);
append(&sb, "update %_content set ");
for(i=0; i<v->nColumn; ++i) {
if( i>0 ){
append(&sb, ", ");
}
append(&sb, v->azContentColumn[i]);
append(&sb, " = ?");
}
append(&sb, " where rowid = ?");
return sb.s;
}
/* 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 ){
const char *zStmt;
int rc;
switch( iStmt ){
case CONTENT_INSERT_STMT:
zStmt = contentInsertStatement(v); break;
case CONTENT_UPDATE_STMT:
zStmt = contentUpdateStatement(v); break;
default:
zStmt = fulltext_zStatement[iStmt];
}
rc = sql_prepare(v->db, v->zDb, v->zName, &v->pFulltextStatements[iStmt],
zStmt);
if( zStmt != fulltext_zStatement[iStmt]) free((void *) zStmt);
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 ){
if( rc==SQLITE_BUSY ) continue;
if( rc!=SQLITE_ERROR ) return rc;
/* If an SQLITE_SCHEMA error has occurred, then finalizing this
* statement is going to delete the fulltext_vtab structure. If
* the statement just executed is in the pFulltextStatements[]
* array, it will be finalized twice. So remove it before
* calling sqlite3_finalize().
*/
v->pFulltextStatements[iStmt] = NULL;
rc = sqlite3_finalize(s);
break;
}
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, ...) values ([rowid], [pValues]) */
static int content_insert(fulltext_vtab *v, sqlite3_value *rowid,
sqlite3_value **pValues){
sqlite3_stmt *s;
int i;
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;
for(i=0; i<v->nColumn; ++i){
rc = sqlite3_bind_value(s, 2+i, pValues[i]);
if( rc!=SQLITE_OK ) return rc;
}
return sql_single_step_statement(v, CONTENT_INSERT_STMT, &s);
}
/* update %_content set col0 = pValues[0], col1 = pValues[1], ...
* where rowid = [iRowid] */
static int content_update(fulltext_vtab *v, sqlite3_value **pValues,
sqlite_int64 iRowid){
sqlite3_stmt *s;
int i;
int rc = sql_get_statement(v, CONTENT_UPDATE_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
for(i=0; i<v->nColumn; ++i){
rc = sqlite3_bind_value(s, 1+i, pValues[i]);
if( rc!=SQLITE_OK ) return rc;
}
rc = sqlite3_bind_int64(s, 1+v->nColumn, iRowid);
if( rc!=SQLITE_OK ) return rc;
return sql_single_step_statement(v, CONTENT_UPDATE_STMT, &s);
}
static void freeStringArray(int nString, const char **pString){
int i;
for (i=0 ; i < nString ; ++i) {
if( pString[i]!=NULL ) free((void *) pString[i]);
}
free((void *) pString);
}
/* select * from %_content where rowid = [iRow]
* The caller must delete the returned array and all strings in it.
* null fields will be NULL in the returned array.
*
* TODO: Perhaps we should return pointer/length strings here for consistency
* with other code which uses pointer/length. */
static int content_select(fulltext_vtab *v, sqlite_int64 iRow,
const char ***pValues){
sqlite3_stmt *s;
const char **values;
int i;
int rc;
*pValues = NULL;
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;
values = (const char **) malloc(v->nColumn * sizeof(const char *));
for(i=0; i<v->nColumn; ++i){
if( sqlite3_column_type(s, i)==SQLITE_NULL ){
values[i] = NULL;
}else{
values[i] = string_dup((char*)sqlite3_column_text(s, i));
}
}
/* 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 ){
*pValues = values;
return SQLITE_OK;
}
freeStringArray(v->nColumn, values);
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 = [pTerm] and segment = [iSegment]
* If found, returns SQLITE_ROW; the caller must free the
* returned doclist. If no rows found, returns SQLITE_DONE. */
static int term_select(fulltext_vtab *v, const char *pTerm, int nTerm,
int iSegment,
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, pTerm, nTerm, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 2, iSegment);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
if( rc!=SQLITE_ROW ) return rc;
*rowid = sqlite3_column_int64(s, 0);
docListInit(out, DL_DEFAULT,
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_ROW : rc;
}
/* Load the segment doclists for term pTerm and merge them in
** appropriate order into out. Returns SQLITE_OK if successful. If
** there are no segments for pTerm, successfully returns an empty
** doclist in out.
**
** Each document consists of 1 or more "columns". The number of
** columns is v->nColumn. If iColumn==v->nColumn, then return
** position information about all columns. If iColumn<v->nColumn,
** then only return position information about the iColumn-th column
** (where the first column is 0).
*/
static int term_select_all(
fulltext_vtab *v, /* The fulltext index we are querying against */
int iColumn, /* If <nColumn, only look at the iColumn-th column */
const char *pTerm, /* The term whose posting lists we want */
int nTerm, /* Number of bytes in pTerm */
DocList *out /* Write the resulting doclist here */
){
DocList doclist;
sqlite3_stmt *s;
int rc = sql_get_statement(v, TERM_SELECT_ALL_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
docListInit(&doclist, DL_DEFAULT, 0, 0);
/* TODO(shess) Handle schema and busy errors. */
while( (rc=sql_step_statement(v, TERM_SELECT_ALL_STMT, &s))==SQLITE_ROW ){
DocList old;
/* TODO(shess) If we processed doclists from oldest to newest, we
** could skip the malloc() involved with the following call. For
** now, I'd rather keep this logic similar to index_insert_term().
** We could additionally drop elements when we see deletes, but
** that would require a distinct version of docListAccumulate().
*/
docListInit(&old, DL_DEFAULT,
sqlite3_column_blob(s, 0), sqlite3_column_bytes(s, 0));
if( iColumn<v->nColumn ){ /* querying a single column */
docListRestrictColumn(&old, iColumn);
}
/* doclist contains the newer data, so write it over old. Then
** steal accumulated result for doclist.
*/
docListAccumulate(&old, &doclist);
docListDestroy(&doclist);
doclist = old;
}
if( rc!=SQLITE_DONE ){
docListDestroy(&doclist);
return rc;
}
docListDiscardEmpty(&doclist);
*out = doclist;
return SQLITE_OK;
}
/* insert into %_term (rowid, term, segment, doclist)
values ([piRowid], [pTerm], [iSegment], [doclist])
** Lets sqlite select rowid if piRowid is NULL, else uses *piRowid.
**
** NOTE(shess) piRowid is IN, with values of "space of int64" plus
** null, it is not used to pass data back to the caller.
*/
static int term_insert(fulltext_vtab *v, sqlite_int64 *piRowid,
const char *pTerm, int nTerm,
int iSegment, DocList *doclist){
sqlite3_stmt *s;
int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
if( piRowid==NULL ){
rc = sqlite3_bind_null(s, 1);
}else{
rc = sqlite3_bind_int64(s, 1, *piRowid);
}
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_text(s, 2, pTerm, nTerm, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 3, iSegment);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_blob(s, 4, 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);
}
/*
** Free the memory used to contain a fulltext_vtab structure.
*/
static void fulltext_vtab_destroy(fulltext_vtab *v){
int iStmt, i;
TRACE(("FTS1 Destroy %p\n", v));
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(v->azColumn);
for(i = 0; i < v->nColumn; ++i) {
sqlite3_free(v->azContentColumn[i]);
}
free(v->azContentColumn);
free(v);
}
/*
** Token types for parsing the arguments to xConnect or xCreate.
*/
#define TOKEN_EOF 0 /* End of file */
#define TOKEN_SPACE 1 /* Any kind of whitespace */
#define TOKEN_ID 2 /* An identifier */
#define TOKEN_STRING 3 /* A string literal */
#define TOKEN_PUNCT 4 /* A single punctuation character */
/*
** If X is a character that can be used in an identifier then
** IdChar(X) will be true. Otherwise it is false.
**
** For ASCII, any character with the high-order bit set is
** allowed in an identifier. For 7-bit characters,
** sqlite3IsIdChar[X] must be 1.
**
** Ticket #1066. the SQL standard does not allow '$' in the
** middle of identfiers. But many SQL implementations do.
** SQLite will allow '$' in identifiers for compatibility.
** But the feature is undocumented.
*/
static const char isIdChar[] = {
/* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* 2x */
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, /* 3x */
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 4x */
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1, /* 5x */
0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6x */
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, /* 7x */
};
#define IdChar(C) (((c=C)&0x80)!=0 || (c>0x1f && isIdChar[c-0x20]))
/*
** Return the length of the token that begins at z[0].
** Store the token type in *tokenType before returning.
*/
static int getToken(const char *z, int *tokenType){
int i, c;
switch( *z ){
case 0: {
*tokenType = TOKEN_EOF;
return 0;
}
case ' ': case '\t': case '\n': case '\f': case '\r': {
for(i=1; safe_isspace(z[i]); i++){}
*tokenType = TOKEN_SPACE;
return i;
}
case '`':
case '\'':
case '"': {
int delim = z[0];
for(i=1; (c=z[i])!=0; i++){
if( c==delim ){
if( z[i+1]==delim ){
i++;
}else{
break;
}
}
}
*tokenType = TOKEN_STRING;
return i + (c!=0);
}
case '[': {
for(i=1, c=z[0]; c!=']' && (c=z[i])!=0; i++){}
*tokenType = TOKEN_ID;
return i;
}
default: {
if( !IdChar(*z) ){
break;
}
for(i=1; IdChar(z[i]); i++){}
*tokenType = TOKEN_ID;
return i;
}
}
*tokenType = TOKEN_PUNCT;
return 1;
}
/*
** A token extracted from a string is an instance of the following
** structure.
*/
typedef struct Token {
const char *z; /* Pointer to token text. Not '\000' terminated */
short int n; /* Length of the token text in bytes. */
} Token;
/*
** Given a input string (which is really one of the argv[] parameters
** passed into xConnect or xCreate) split the string up into tokens.
** Return an array of pointers to '\000' terminated strings, one string
** for each non-whitespace token.
**
** The returned array is terminated by a single NULL pointer.
**
** Space to hold the returned array is obtained from a single
** malloc and should be freed by passing the return value to free().
** The individual strings within the token list are all a part of
** the single memory allocation and will all be freed at once.
*/
static char **tokenizeString(const char *z, int *pnToken){
int nToken = 0;
Token *aToken = malloc( strlen(z) * sizeof(aToken[0]) );
int n = 1;
int e, i;
int totalSize = 0;
char **azToken;
char *zCopy;
while( n>0 ){
n = getToken(z, &e);
if( e!=TOKEN_SPACE ){
aToken[nToken].z = z;
aToken[nToken].n = n;
nToken++;
totalSize += n+1;
}
z += n;
}
azToken = (char**)malloc( nToken*sizeof(char*) + totalSize );
zCopy = (char*)&azToken[nToken];
nToken--;
for(i=0; i<nToken; i++){
azToken[i] = zCopy;
n = aToken[i].n;
memcpy(zCopy, aToken[i].z, n);
zCopy[n] = 0;
zCopy += n+1;
}
azToken[nToken] = 0;
free(aToken);
*pnToken = nToken;
return azToken;
}
/*
** Convert an SQL-style quoted string into a normal string by removing
** the quote characters. The conversion is done in-place. If the
** input does not begin with a quote character, then this routine
** is a no-op.
**
** Examples:
**
** "abc" becomes abc
** 'xyz' becomes xyz
** [pqr] becomes pqr
** `mno` becomes mno
*/
static void dequoteString(char *z){
int quote;
int i, j;
if( z==0 ) return;
quote = z[0];
switch( quote ){
case '\'': break;
case '"': break;
case '`': break; /* For MySQL compatibility */
case '[': quote = ']'; break; /* For MS SqlServer compatibility */
default: return;
}
for(i=1, j=0; z[i]; i++){
if( z[i]==quote ){
if( z[i+1]==quote ){
z[j++] = quote;
i++;
}else{
z[j++] = 0;
break;
}
}else{
z[j++] = z[i];
}
}
}
/*
** The input azIn is a NULL-terminated list of tokens. Remove the first
** token and all punctuation tokens. Remove the quotes from
** around string literal tokens.
**
** Example:
**
** input: tokenize chinese ( 'simplifed' , 'mixed' )
** output: chinese simplifed mixed
**
** Another example:
**
** input: delimiters ( '[' , ']' , '...' )
** output: [ ] ...
*/
static void tokenListToIdList(char **azIn){
int i, j;
if( azIn ){
for(i=0, j=-1; azIn[i]; i++){
if( safe_isalnum(azIn[i][0]) || azIn[i][1] ){
dequoteString(azIn[i]);
if( j>=0 ){
azIn[j] = azIn[i];
}
j++;
}
}
azIn[j] = 0;
}
}
/*
** Find the first alphanumeric token in the string zIn. Null-terminate
** this token. Remove any quotation marks. And return a pointer to
** the result.
*/
static char *firstToken(char *zIn, char **pzTail){
int n, ttype;
while(1){
n = getToken(zIn, &ttype);
if( ttype==TOKEN_SPACE ){
zIn += n;
}else if( ttype==TOKEN_EOF ){
*pzTail = zIn;
return 0;
}else{
zIn[n] = 0;
*pzTail = &zIn[1];
dequoteString(zIn);
return zIn;
}
}
/*NOTREACHED*/
}
/* Return true if...
**
** * s begins with the string t, ignoring case
** * s is longer than t
** * The first character of s beyond t is not a alphanumeric
**
** Ignore leading space in *s.
**
** To put it another way, return true if the first token of
** s[] is t[].
*/
static int startsWith(const char *s, const char *t){
while( safe_isspace(*s) ){ s++; }
while( *t ){
if( safe_tolower(*s++)!=safe_tolower(*t++) ) return 0;
}
return *s!='_' && !safe_isalnum(*s);
}
/*
** An instance of this structure defines the "spec" of a
** full text index. This structure is populated by parseSpec
** and use by fulltextConnect and fulltextCreate.
*/
typedef struct TableSpec {
const char *zDb; /* Logical database name */
const char *zName; /* Name of the full-text index */
int nColumn; /* Number of columns to be indexed */
char **azColumn; /* Original names of columns to be indexed */
char **azContentColumn; /* Column names for %_content */
char **azTokenizer; /* Name of tokenizer and its arguments */
} TableSpec;
/*
** Reclaim all of the memory used by a TableSpec
*/
static void clearTableSpec(TableSpec *p) {
free(p->azColumn);
free(p->azContentColumn);
free(p->azTokenizer);
}
/* Parse a CREATE VIRTUAL TABLE statement, which looks like this:
*
* CREATE VIRTUAL TABLE email
* USING fts1(subject, body, tokenize mytokenizer(myarg))
*
* We return parsed information in a TableSpec structure.
*
*/
static int parseSpec(TableSpec *pSpec, int argc, const char *const*argv,
char**pzErr){
int i, n;
char *z, *zDummy;
char **azArg;
const char *zTokenizer = 0; /* argv[] entry describing the tokenizer */
assert( argc>=3 );
/* Current interface:
** argv[0] - module name
** argv[1] - database name
** argv[2] - table name
** argv[3..] - columns, optionally followed by tokenizer specification
** and snippet delimiters specification.
*/
/* Make a copy of the complete argv[][] array in a single allocation.
** The argv[][] array is read-only and transient. We can write to the
** copy in order to modify things and the copy is persistent.
*/
memset(pSpec, 0, sizeof(*pSpec));
for(i=n=0; i<argc; i++){
n += strlen(argv[i]) + 1;
}
azArg = malloc( sizeof(char*)*argc + n );
if( azArg==0 ){
return SQLITE_NOMEM;
}
z = (char*)&azArg[argc];
for(i=0; i<argc; i++){
azArg[i] = z;
strcpy(z, argv[i]);
z += strlen(z)+1;
}
/* Identify the column names and the tokenizer and delimiter arguments
** in the argv[][] array.
*/
pSpec->zDb = azArg[1];
pSpec->zName = azArg[2];
pSpec->nColumn = 0;
pSpec->azColumn = azArg;
zTokenizer = "tokenize simple";
for(i=3; i<argc; ++i){
if( startsWith(azArg[i],"tokenize") ){
zTokenizer = azArg[i];
}else{
z = azArg[pSpec->nColumn] = firstToken(azArg[i], &zDummy);
pSpec->nColumn++;
}
}
if( pSpec->nColumn==0 ){
azArg[0] = "content";
pSpec->nColumn = 1;
}
/*
** Construct the list of content column names.
**
** Each content column name will be of the form cNNAAAA
** where NN is the column number and AAAA is the sanitized
** column name. "sanitized" means that special characters are
** converted to "_". The cNN prefix guarantees that all column
** names are unique.
**
** The AAAA suffix is not strictly necessary. It is included
** for the convenience of people who might examine the generated
** %_content table and wonder what the columns are used for.
*/
pSpec->azContentColumn = malloc( pSpec->nColumn * sizeof(char *) );
if( pSpec->azContentColumn==0 ){
clearTableSpec(pSpec);
return SQLITE_NOMEM;
}
for(i=0; i<pSpec->nColumn; i++){
char *p;
pSpec->azContentColumn[i] = sqlite3_mprintf("c%d%s", i, azArg[i]);
for (p = pSpec->azContentColumn[i]; *p ; ++p) {
if( !safe_isalnum(*p) ) *p = '_';
}
}
/*
** Parse the tokenizer specification string.
*/
pSpec->azTokenizer = tokenizeString(zTokenizer, &n);
tokenListToIdList(pSpec->azTokenizer);
return SQLITE_OK;
}
/*
** Generate a CREATE TABLE statement that describes the schema of
** the virtual table. Return a pointer to this schema string.
**
** Space is obtained from sqlite3_mprintf() and should be freed
** using sqlite3_free().
*/
static char *fulltextSchema(
int nColumn, /* Number of columns */
const char *const* azColumn, /* List of columns */
const char *zTableName /* Name of the table */
){
int i;
char *zSchema, *zNext;
const char *zSep = "(";
zSchema = sqlite3_mprintf("CREATE TABLE x");
for(i=0; i<nColumn; i++){
zNext = sqlite3_mprintf("%s%s%Q", zSchema, zSep, azColumn[i]);
sqlite3_free(zSchema);
zSchema = zNext;
zSep = ",";
}
zNext = sqlite3_mprintf("%s,%Q)", zSchema, zTableName);
sqlite3_free(zSchema);
return zNext;
}
/*
** Build a new sqlite3_vtab structure that will describe the
** fulltext index defined by spec.
*/
static int constructVtab(
sqlite3 *db, /* The SQLite database connection */
TableSpec *spec, /* Parsed spec information from parseSpec() */
sqlite3_vtab **ppVTab, /* Write the resulting vtab structure here */
char **pzErr /* Write any error message here */
){
int rc;
int n;
fulltext_vtab *v = 0;
const sqlite3_tokenizer_module *m = NULL;
char *schema;
v = (fulltext_vtab *) malloc(sizeof(fulltext_vtab));
if( v==0 ) return SQLITE_NOMEM;
memset(v, 0, sizeof(*v));
/* sqlite will initialize v->base */
v->db = db;
v->zDb = spec->zDb; /* Freed when azColumn is freed */
v->zName = spec->zName; /* Freed when azColumn is freed */
v->nColumn = spec->nColumn;
v->azContentColumn = spec->azContentColumn;
spec->azContentColumn = 0;
v->azColumn = spec->azColumn;
spec->azColumn = 0;
if( spec->azTokenizer==0 ){
return SQLITE_NOMEM;
}
/* TODO(shess) For now, add new tokenizers as else if clauses. */
if( spec->azTokenizer[0]==0 || startsWith(spec->azTokenizer[0], "simple") ){
sqlite3Fts1SimpleTokenizerModule(&m);
}else if( startsWith(spec->azTokenizer[0], "porter") ){
sqlite3Fts1PorterTokenizerModule(&m);
}else{
*pzErr = sqlite3_mprintf("unknown tokenizer: %s", spec->azTokenizer[0]);
rc = SQLITE_ERROR;
goto err;
}
for(n=0; spec->azTokenizer[n]; n++){}
if( n ){
rc = m->xCreate(n-1, (const char*const*)&spec->azTokenizer[1],
&v->pTokenizer);
}else{
rc = m->xCreate(0, 0, &v->pTokenizer);
}
if( rc!=SQLITE_OK ) goto err;
v->pTokenizer->pModule = m;
/* TODO: verify the existence of backing tables foo_content, foo_term */
schema = fulltextSchema(v->nColumn, (const char*const*)v->azColumn,
spec->zName);
rc = sqlite3_declare_vtab(db, schema);
sqlite3_free(schema);
if( rc!=SQLITE_OK ) goto err;
memset(v->pFulltextStatements, 0, sizeof(v->pFulltextStatements));
*ppVTab = &v->base;
TRACE(("FTS1 Connect %p\n", v));
return rc;
err:
fulltext_vtab_destroy(v);
return rc;
}
static int fulltextConnect(
sqlite3 *db,
void *pAux,
int argc, const char *const*argv,
sqlite3_vtab **ppVTab,
char **pzErr
){
TableSpec spec;
int rc = parseSpec(&spec, argc, argv, pzErr);
if( rc!=SQLITE_OK ) return rc;
rc = constructVtab(db, &spec, ppVTab, pzErr);
clearTableSpec(&spec);
return rc;
}
/* The %_content table holds the text of each document, 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 elements:
** position+1 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
**
** The sentinel position of 0 indicates the end of the token list.
**
** Additionally, doclist blobs are chunked into multiple segments,
** using segment to order the segments. New elements are added to
** the segment at segment 0, until it exceeds CHUNK_MAX. Then
** segment 0 is deleted, and the doclist is inserted at segment 1.
** If there is already a doclist at segment 1, the segment 0 doclist
** is merged with it, the segment 1 doclist is deleted, and the
** merged doclist is inserted at segment 2, repeating those
** operations until an insert succeeds.
**
** Since this structure doesn't allow us to update elements in place
** in case of deletion or update, these are simply written to
** segment 0 (with an empty token list in case of deletion), with
** docListAccumulate() taking care to retain lower-segment
** information in preference to higher-segment information.
*/
/* TODO(shess) Provide a VACUUM type operation which both removes
** deleted elements which are no longer necessary, and duplicated
** elements. I suspect this will probably not be necessary in
** practice, though.
*/
static int fulltextCreate(sqlite3 *db, void *pAux,
int argc, const char * const *argv,
sqlite3_vtab **ppVTab, char **pzErr){
int rc;
TableSpec spec;
StringBuffer schema;
TRACE(("FTS1 Create\n"));
rc = parseSpec(&spec, argc, argv, pzErr);
if( rc!=SQLITE_OK ) return rc;
initStringBuffer(&schema);
append(&schema, "CREATE TABLE %_content(");
appendList(&schema, spec.nColumn, spec.azContentColumn);
append(&schema, ")");
rc = sql_exec(db, spec.zDb, spec.zName, schema.s);
free(schema.s);
if( rc!=SQLITE_OK ) goto out;
rc = sql_exec(db, spec.zDb, spec.zName,
"create table %_term(term text, segment integer, doclist blob, "
"primary key(term, segment));");
if( rc!=SQLITE_OK ) goto out;
rc = constructVtab(db, &spec, ppVTab, pzErr);
out:
clearTableSpec(&spec);
return rc;
}
/* Decide how to handle an SQL query. */
static int fulltextBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
int i;
TRACE(("FTS1 BestIndex\n"));
for(i=0; i<pInfo->nConstraint; ++i){
const struct sqlite3_index_constraint *pConstraint;
pConstraint = &pInfo->aConstraint[i];
if( pConstraint->usable ) {
if( pConstraint->iColumn==-1 &&
pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ ){
pInfo->idxNum = QUERY_ROWID; /* lookup by rowid */
TRACE(("FTS1 QUERY_ROWID\n"));
} else if( pConstraint->iColumn>=0 &&
pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
/* full-text search */
pInfo->idxNum = QUERY_FULLTEXT + pConstraint->iColumn;
TRACE(("FTS1 QUERY_FULLTEXT %d\n", pConstraint->iColumn));
} else continue;
pInfo->aConstraintUsage[i].argvIndex = 1;
pInfo->aConstraintUsage[i].omit = 1;
/* An arbitrary value for now.
* TODO: Perhaps rowid matches should be considered cheaper than
* full-text searches. */
pInfo->estimatedCost = 1.0;
return SQLITE_OK;
}
}
pInfo->idxNum = QUERY_GENERIC;
return SQLITE_OK;
}
static int fulltextDisconnect(sqlite3_vtab *pVTab){
TRACE(("FTS1 Disconnect %p\n", pVTab));
fulltext_vtab_destroy((fulltext_vtab *)pVTab);
return SQLITE_OK;
}
static int fulltextDestroy(sqlite3_vtab *pVTab){
fulltext_vtab *v = (fulltext_vtab *)pVTab;
int rc;
TRACE(("FTS1 Destroy %p\n", pVTab));
rc = sql_exec(v->db, v->zDb, v->zName,
"drop table if exists %_content;"
"drop table if exists %_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;
TRACE(("FTS1 Open %p: %p\n", pVTab, c));
return SQLITE_OK;
}
/* Free all of the dynamically allocated memory held by *q
*/
static void queryClear(Query *q){
int i;
for(i = 0; i < q->nTerms; ++i){
free(q->pTerms[i].pTerm);
}
free(q->pTerms);
memset(q, 0, sizeof(*q));
}
/* Free all of the dynamically allocated memory held by the
** Snippet
*/
static void snippetClear(Snippet *p){
free(p->aMatch);
free(p->zOffset);
free(p->zSnippet);
memset(p, 0, sizeof(*p));
}
/*
** Append a single entry to the p->aMatch[] log.
*/
static void snippetAppendMatch(
Snippet *p, /* Append the entry to this snippet */
int iCol, int iTerm, /* The column and query term */
int iStart, int nByte /* Offset and size of the match */
){
int i;
struct snippetMatch *pMatch;
if( p->nMatch+1>=p->nAlloc ){
p->nAlloc = p->nAlloc*2 + 10;
p->aMatch = realloc(p->aMatch, p->nAlloc*sizeof(p->aMatch[0]) );
if( p->aMatch==0 ){
p->nMatch = 0;
p->nAlloc = 0;
return;
}
}
i = p->nMatch++;
pMatch = &p->aMatch[i];
pMatch->iCol = iCol;
pMatch->iTerm = iTerm;
pMatch->iStart = iStart;
pMatch->nByte = nByte;
}
/*
** Sizing information for the circular buffer used in snippetOffsetsOfColumn()
*/
#define FTS1_ROTOR_SZ (32)
#define FTS1_ROTOR_MASK (FTS1_ROTOR_SZ-1)
/*
** Add entries to pSnippet->aMatch[] for every match that occurs against
** document zDoc[0..nDoc-1] which is stored in column iColumn.
*/
static void snippetOffsetsOfColumn(
Query *pQuery,
Snippet *pSnippet,
int iColumn,
const char *zDoc,
int nDoc
){
const sqlite3_tokenizer_module *pTModule; /* The tokenizer module */
sqlite3_tokenizer *pTokenizer; /* The specific tokenizer */
sqlite3_tokenizer_cursor *pTCursor; /* Tokenizer cursor */
fulltext_vtab *pVtab; /* The full text index */
int nColumn; /* Number of columns in the index */
const QueryTerm *aTerm; /* Query string terms */
int nTerm; /* Number of query string terms */
int i, j; /* Loop counters */
int rc; /* Return code */
unsigned int match, prevMatch; /* Phrase search bitmasks */
const char *zToken; /* Next token from the tokenizer */
int nToken; /* Size of zToken */
int iBegin, iEnd, iPos; /* Offsets of beginning and end */
/* The following variables keep a circular buffer of the last
** few tokens */
unsigned int iRotor = 0; /* Index of current token */
int iRotorBegin[FTS1_ROTOR_SZ]; /* Beginning offset of token */
int iRotorLen[FTS1_ROTOR_SZ]; /* Length of token */
pVtab = pQuery->pFts;
nColumn = pVtab->nColumn;
pTokenizer = pVtab->pTokenizer;
pTModule = pTokenizer->pModule;
rc = pTModule->xOpen(pTokenizer, zDoc, nDoc, &pTCursor);
if( rc ) return;
pTCursor->pTokenizer = pTokenizer;
aTerm = pQuery->pTerms;
nTerm = pQuery->nTerms;
if( nTerm>=FTS1_ROTOR_SZ ){
nTerm = FTS1_ROTOR_SZ - 1;
}
prevMatch = 0;
while(1){
rc = pTModule->xNext(pTCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
if( rc ) break;
iRotorBegin[iRotor&FTS1_ROTOR_MASK] = iBegin;
iRotorLen[iRotor&FTS1_ROTOR_MASK] = iEnd-iBegin;
match = 0;
for(i=0; i<nTerm; i++){
int iCol;
iCol = aTerm[i].iColumn;
if( iCol>=0 && iCol<nColumn && iCol!=iColumn ) continue;
if( aTerm[i].nTerm!=nToken ) continue;
if( memcmp(aTerm[i].pTerm, zToken, nToken) ) continue;
if( aTerm[i].iPhrase>1 && (prevMatch & (1<<i))==0 ) continue;
match |= 1<<i;
if( i==nTerm-1 || aTerm[i+1].iPhrase==1 ){
for(j=aTerm[i].iPhrase-1; j>=0; j--){
int k = (iRotor-j) & FTS1_ROTOR_MASK;
snippetAppendMatch(pSnippet, iColumn, i-j,
iRotorBegin[k], iRotorLen[k]);
}
}
}
prevMatch = match<<1;
iRotor++;
}
pTModule->xClose(pTCursor);
}
/*
** Compute all offsets for the current row of the query.
** If the offsets have already been computed, this routine is a no-op.
*/
static void snippetAllOffsets(fulltext_cursor *p){
int nColumn;
int iColumn, i;
int iFirst, iLast;
fulltext_vtab *pFts;
if( p->snippet.nMatch ) return;
if( p->q.nTerms==0 ) return;
pFts = p->q.pFts;
nColumn = pFts->nColumn;
iColumn = p->iCursorType - QUERY_FULLTEXT;
if( iColumn<0 || iColumn>=nColumn ){
iFirst = 0;
iLast = nColumn-1;
}else{
iFirst = iColumn;
iLast = iColumn;
}
for(i=iFirst; i<=iLast; i++){
const char *zDoc;
int nDoc;
zDoc = (const char*)sqlite3_column_text(p->pStmt, i+1);
nDoc = sqlite3_column_bytes(p->pStmt, i+1);
snippetOffsetsOfColumn(&p->q, &p->snippet, i, zDoc, nDoc);
}
}
/*
** Convert the information in the aMatch[] array of the snippet
** into the string zOffset[0..nOffset-1].
*/
static void snippetOffsetText(Snippet *p){
int i;
int cnt = 0;
StringBuffer sb;
char zBuf[200];
if( p->zOffset ) return;
initStringBuffer(&sb);
for(i=0; i<p->nMatch; i++){
struct snippetMatch *pMatch = &p->aMatch[i];
zBuf[0] = ' ';
sqlite3_snprintf(sizeof(zBuf)-1, &zBuf[cnt>0], "%d %d %d %d",
pMatch->iCol, pMatch->iTerm, pMatch->iStart, pMatch->nByte);
append(&sb, zBuf);
cnt++;
}
p->zOffset = sb.s;
p->nOffset = sb.len;
}
/*
** zDoc[0..nDoc-1] is phrase of text. aMatch[0..nMatch-1] are a set
** of matching words some of which might be in zDoc. zDoc is column
** number iCol.
**
** iBreak is suggested spot in zDoc where we could begin or end an
** excerpt. Return a value similar to iBreak but possibly adjusted
** to be a little left or right so that the break point is better.
*/
static int wordBoundary(
int iBreak, /* The suggested break point */
const char *zDoc, /* Document text */
int nDoc, /* Number of bytes in zDoc[] */
struct snippetMatch *aMatch, /* Matching words */
int nMatch, /* Number of entries in aMatch[] */
int iCol /* The column number for zDoc[] */
){
int i;
if( iBreak<=10 ){
return 0;
}
if( iBreak>=nDoc-10 ){
return nDoc;
}
for(i=0; i<nMatch && aMatch[i].iCol<iCol; i++){}
while( i<nMatch && aMatch[i].iStart+aMatch[i].nByte<iBreak ){ i++; }
if( i<nMatch ){
if( aMatch[i].iStart<iBreak+10 ){
return aMatch[i].iStart;
}
if( i>0 && aMatch[i-1].iStart+aMatch[i-1].nByte>=iBreak ){
return aMatch[i-1].iStart;
}
}
for(i=1; i<=10; i++){
if( safe_isspace(zDoc[iBreak-i]) ){
return iBreak - i + 1;
}
if( safe_isspace(zDoc[iBreak+i]) ){
return iBreak + i + 1;
}
}
return iBreak;
}
/*
** If the StringBuffer does not end in white space, add a single
** space character to the end.
*/
static void appendWhiteSpace(StringBuffer *p){
if( p->len==0 ) return;
if( safe_isspace(p->s[p->len-1]) ) return;
append(p, " ");
}
/*
** Remove white space from teh end of the StringBuffer
*/
static void trimWhiteSpace(StringBuffer *p){
while( p->len>0 && safe_isspace(p->s[p->len-1]) ){
p->len--;
}
}
/*
** Allowed values for Snippet.aMatch[].snStatus
*/
#define SNIPPET_IGNORE 0 /* It is ok to omit this match from the snippet */
#define SNIPPET_DESIRED 1 /* We want to include this match in the snippet */
/*
** Generate the text of a snippet.
*/
static void snippetText(
fulltext_cursor *pCursor, /* The cursor we need the snippet for */
const char *zStartMark, /* Markup to appear before each match */
const char *zEndMark, /* Markup to appear after each match */
const char *zEllipsis /* Ellipsis mark */
){
int i, j;
struct snippetMatch *aMatch;
int nMatch;
int nDesired;
StringBuffer sb;
int tailCol;
int tailOffset;
int iCol;
int nDoc;
const char *zDoc;
int iStart, iEnd;
int tailEllipsis = 0;
int iMatch;
free(pCursor->snippet.zSnippet);
pCursor->snippet.zSnippet = 0;
aMatch = pCursor->snippet.aMatch;
nMatch = pCursor->snippet.nMatch;
initStringBuffer(&sb);
for(i=0; i<nMatch; i++){
aMatch[i].snStatus = SNIPPET_IGNORE;
}
nDesired = 0;
for(i=0; i<pCursor->q.nTerms; i++){
for(j=0; j<nMatch; j++){
if( aMatch[j].iTerm==i ){
aMatch[j].snStatus = SNIPPET_DESIRED;
nDesired++;
break;
}
}
}
iMatch = 0;
tailCol = -1;
tailOffset = 0;
for(i=0; i<nMatch && nDesired>0; i++){
if( aMatch[i].snStatus!=SNIPPET_DESIRED ) continue;
nDesired--;
iCol = aMatch[i].iCol;
zDoc = (const char*)sqlite3_column_text(pCursor->pStmt, iCol+1);
nDoc = sqlite3_column_bytes(pCursor->pStmt, iCol+1);
iStart = aMatch[i].iStart - 40;
iStart = wordBoundary(iStart, zDoc, nDoc, aMatch, nMatch, iCol);
if( iStart<=10 ){
iStart = 0;
}
if( iCol==tailCol && iStart<=tailOffset+20 ){
iStart = tailOffset;
}
if( (iCol!=tailCol && tailCol>=0) || iStart!=tailOffset ){
trimWhiteSpace(&sb);
appendWhiteSpace(&sb);
append(&sb, zEllipsis);
appendWhiteSpace(&sb);
}
iEnd = aMatch[i].iStart + aMatch[i].nByte + 40;
iEnd = wordBoundary(iEnd, zDoc, nDoc, aMatch, nMatch, iCol);
if( iEnd>=nDoc-10 ){
iEnd = nDoc;
tailEllipsis = 0;
}else{
tailEllipsis = 1;
}
while( iMatch<nMatch && aMatch[iMatch].iCol<iCol ){ iMatch++; }
while( iStart<iEnd ){
while( iMatch<nMatch && aMatch[iMatch].iStart<iStart
&& aMatch[iMatch].iCol<=iCol ){
iMatch++;
}
if( iMatch<nMatch && aMatch[iMatch].iStart<iEnd
&& aMatch[iMatch].iCol==iCol ){
nappend(&sb, &zDoc[iStart], aMatch[iMatch].iStart - iStart);
iStart = aMatch[iMatch].iStart;
append(&sb, zStartMark);
nappend(&sb, &zDoc[iStart], aMatch[iMatch].nByte);
append(&sb, zEndMark);
iStart += aMatch[iMatch].nByte;
for(j=iMatch+1; j<nMatch; j++){
if( aMatch[j].iTerm==aMatch[iMatch].iTerm
&& aMatch[j].snStatus==SNIPPET_DESIRED ){
nDesired--;
aMatch[j].snStatus = SNIPPET_IGNORE;
}
}
}else{
nappend(&sb, &zDoc[iStart], iEnd - iStart);
iStart = iEnd;
}
}
tailCol = iCol;
tailOffset = iEnd;
}
trimWhiteSpace(&sb);
if( tailEllipsis ){
appendWhiteSpace(&sb);
append(&sb, zEllipsis);
}
pCursor->snippet.zSnippet = sb.s;
pCursor->snippet.nSnippet = sb.len;
}
/*
** Close the cursor. For additional information see the documentation
** on the xClose method of the virtual table interface.
*/
static int fulltextClose(sqlite3_vtab_cursor *pCursor){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
TRACE(("FTS1 Close %p\n", c));
sqlite3_finalize(c->pStmt);
queryClear(&c->q);
snippetClear(&c->snippet);
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;
TRACE(("FTS1 Next %p\n", pCursor));
snippetClear(&c->snippet);
if( c->iCursorType < QUERY_FULLTEXT ){
/* 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;
}
} else { /* full-text query */
rc = sqlite3_reset(c->pStmt);
if( rc!=SQLITE_OK ) return rc;
iDocid = nextDocid(&c->result);
if( iDocid==0 ){
c->eof = 1;
return SQLITE_OK;
}
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;
}
}
/* Return a DocList corresponding to the query term *pTerm. If *pTerm
** is the first term of a phrase query, go ahead and evaluate the phrase
** query and return the doclist for the entire phrase query.
**
** The result is stored in pTerm->doclist.
*/
static int docListOfTerm(
fulltext_vtab *v, /* The full text index */
int iColumn, /* column to restrict to. No restrition if >=nColumn */
QueryTerm *pQTerm, /* Term we are looking for, or 1st term of a phrase */
DocList **ppResult /* Write the result here */
){
DocList *pLeft, *pRight, *pNew;
int i, rc;
pLeft = docListNew(DL_POSITIONS);
rc = term_select_all(v, iColumn, pQTerm->pTerm, pQTerm->nTerm, pLeft);
if( rc ){
docListDelete(pLeft);
return rc;
}
for(i=1; i<=pQTerm->nPhrase; i++){
pRight = docListNew(DL_POSITIONS);
rc = term_select_all(v, iColumn, pQTerm[i].pTerm, pQTerm[i].nTerm, pRight);
if( rc ){
docListDelete(pLeft);
return rc;
}
pNew = docListNew(i<pQTerm->nPhrase ? DL_POSITIONS : DL_DOCIDS);
docListPhraseMerge(pLeft, pRight, pNew);
docListDelete(pLeft);
docListDelete(pRight);
pLeft = pNew;
}
*ppResult = pLeft;
return SQLITE_OK;
}
/* Add a new term pTerm[0..nTerm-1] to the query *q.
*/
static void queryAdd(Query *q, const char *pTerm, int nTerm){
QueryTerm *t;
++q->nTerms;
q->pTerms = realloc(q->pTerms, q->nTerms * sizeof(q->pTerms[0]));
if( q->pTerms==0 ){
q->nTerms = 0;
return;
}
t = &q->pTerms[q->nTerms - 1];
memset(t, 0, sizeof(*t));
t->pTerm = malloc(nTerm+1);
memcpy(t->pTerm, pTerm, nTerm);
t->pTerm[nTerm] = 0;
t->nTerm = nTerm;
t->isOr = q->nextIsOr;
q->nextIsOr = 0;
t->iColumn = q->nextColumn;
q->nextColumn = q->dfltColumn;
}
/*
** Check to see if the string zToken[0...nToken-1] matches any
** column name in the virtual table. If it does,
** return the zero-indexed column number. If not, return -1.
*/
static int checkColumnSpecifier(
fulltext_vtab *pVtab, /* The virtual table */
const char *zToken, /* Text of the token */
int nToken /* Number of characters in the token */
){
int i;
for(i=0; i<pVtab->nColumn; i++){
if( memcmp(pVtab->azColumn[i], zToken, nToken)==0
&& pVtab->azColumn[i][nToken]==0 ){
return i;
}
}
return -1;
}
/*
** Parse the text at pSegment[0..nSegment-1]. Add additional terms
** to the query being assemblied in pQuery.
**
** inPhrase is true if pSegment[0..nSegement-1] is contained within
** double-quotes. If inPhrase is true, then the first term
** is marked with the number of terms in the phrase less one and
** OR and "-" syntax is ignored. If inPhrase is false, then every
** term found is marked with nPhrase=0 and OR and "-" syntax is significant.
*/
static int tokenizeSegment(
sqlite3_tokenizer *pTokenizer, /* The tokenizer to use */
const char *pSegment, int nSegment, /* Query expression being parsed */
int inPhrase, /* True if within "..." */
Query *pQuery /* Append results here */
){
const sqlite3_tokenizer_module *pModule = pTokenizer->pModule;
sqlite3_tokenizer_cursor *pCursor;
int firstIndex = pQuery->nTerms;
int iCol;
int nTerm = 1;
int rc = pModule->xOpen(pTokenizer, pSegment, nSegment, &pCursor);
if( rc!=SQLITE_OK ) return rc;
pCursor->pTokenizer = pTokenizer;
while( 1 ){
const char *pToken;
int nToken, iBegin, iEnd, iPos;
rc = pModule->xNext(pCursor,
&pToken, &nToken,
&iBegin, &iEnd, &iPos);
if( rc!=SQLITE_OK ) break;
if( !inPhrase &&
pSegment[iEnd]==':' &&
(iCol = checkColumnSpecifier(pQuery->pFts, pToken, nToken))>=0 ){
pQuery->nextColumn = iCol;
continue;
}
if( !inPhrase && pQuery->nTerms>0 && nToken==2
&& pSegment[iBegin]=='O' && pSegment[iBegin+1]=='R' ){
pQuery->nextIsOr = 1;
continue;
}
queryAdd(pQuery, pToken, nToken);
if( !inPhrase && iBegin>0 && pSegment[iBegin-1]=='-' ){
pQuery->pTerms[pQuery->nTerms-1].isNot = 1;
}
pQuery->pTerms[pQuery->nTerms-1].iPhrase = nTerm;
if( inPhrase ){
nTerm++;
}
}
if( inPhrase && pQuery->nTerms>firstIndex ){
pQuery->pTerms[firstIndex].nPhrase = pQuery->nTerms - firstIndex - 1;
}
return pModule->xClose(pCursor);
}
/* Parse a query string, yielding a Query object pQuery.
**
** The calling function will need to queryClear() to clean up
** the dynamically allocated memory held by pQuery.
*/
static int parseQuery(
fulltext_vtab *v, /* The fulltext index */
const char *zInput, /* Input text of the query string */
int nInput, /* Size of the input text */
int dfltColumn, /* Default column of the index to match against */
Query *pQuery /* Write the parse results here. */
){
int iInput, inPhrase = 0;
if( zInput==0 ) nInput = 0;
if( nInput<0 ) nInput = strlen(zInput);
pQuery->nTerms = 0;
pQuery->pTerms = NULL;
pQuery->nextIsOr = 0;
pQuery->nextColumn = dfltColumn;
pQuery->dfltColumn = dfltColumn;
pQuery->pFts = v;
for(iInput=0; iInput<nInput; ++iInput){
int i;
for(i=iInput; i<nInput && zInput[i]!='"'; ++i){}
if( i>iInput ){
tokenizeSegment(v->pTokenizer, zInput+iInput, i-iInput, inPhrase,
pQuery);
}
iInput = i;
if( i<nInput ){
assert( zInput[i]=='"' );
inPhrase = !inPhrase;
}
}
if( inPhrase ){
/* unmatched quote */
queryClear(pQuery);
return SQLITE_ERROR;
}
return SQLITE_OK;
}
/* Perform a full-text query using the search expression in
** zInput[0..nInput-1]. Return a list of matching documents
** in pResult.
**
** Queries must match column iColumn. Or if iColumn>=nColumn
** they are allowed to match against any column.
*/
static int fulltextQuery(
fulltext_vtab *v, /* The full text index */
int iColumn, /* Match against this column by default */
const char *zInput, /* The query string */
int nInput, /* Number of bytes in zInput[] */
DocList **pResult, /* Write the result doclist here */
Query *pQuery /* Put parsed query string here */
){
int i, iNext, rc;
DocList *pLeft = NULL;
DocList *pRight, *pNew, *pOr;
int nNot = 0;
QueryTerm *aTerm;
rc = parseQuery(v, zInput, nInput, iColumn, pQuery);
if( rc!=SQLITE_OK ) return rc;
/* Merge AND terms. */
aTerm = pQuery->pTerms;
for(i = 0; i<pQuery->nTerms; i=iNext){
if( aTerm[i].isNot ){
/* Handle all NOT terms in a separate pass */
nNot++;
iNext = i + aTerm[i].nPhrase+1;
continue;
}
iNext = i + aTerm[i].nPhrase + 1;
rc = docListOfTerm(v, aTerm[i].iColumn, &aTerm[i], &pRight);
if( rc ){
queryClear(pQuery);
return rc;
}
while( iNext<pQuery->nTerms && aTerm[iNext].isOr ){
rc = docListOfTerm(v, aTerm[iNext].iColumn, &aTerm[iNext], &pOr);
iNext += aTerm[iNext].nPhrase + 1;
if( rc ){
queryClear(pQuery);
return rc;
}
pNew = docListNew(DL_DOCIDS);
docListOrMerge(pRight, pOr, pNew);
docListDelete(pRight);
docListDelete(pOr);
pRight = pNew;
}
if( pLeft==0 ){
pLeft = pRight;
}else{
pNew = docListNew(DL_DOCIDS);
docListAndMerge(pLeft, pRight, pNew);
docListDelete(pRight);
docListDelete(pLeft);
pLeft = pNew;
}
}
if( nNot && pLeft==0 ){
/* We do not yet know how to handle a query of only NOT terms */
return SQLITE_ERROR;
}
/* Do the EXCEPT terms */
for(i=0; i<pQuery->nTerms; i += aTerm[i].nPhrase + 1){
if( !aTerm[i].isNot ) continue;
rc = docListOfTerm(v, aTerm[i].iColumn, &aTerm[i], &pRight);
if( rc ){
queryClear(pQuery);
docListDelete(pLeft);
return rc;
}
pNew = docListNew(DL_DOCIDS);
docListExceptMerge(pLeft, pRight, pNew);
docListDelete(pRight);
docListDelete(pLeft);
pLeft = pNew;
}
*pResult = pLeft;
return rc;
}
/*
** This is the xFilter interface for the virtual table. See
** the virtual table xFilter method documentation for additional
** information.
**
** If idxNum==QUERY_GENERIC then do a full table scan against
** the %_content table.
**
** If idxNum==QUERY_ROWID then do a rowid lookup for a single entry
** in the %_content table.
**
** If idxNum>=QUERY_FULLTEXT then use the full text index. The
** column on the left-hand side of the MATCH operator is column
** number idxNum-QUERY_FULLTEXT, 0 indexed. argv[0] is the right-hand
** side of the MATCH operator.
*/
/* TODO(shess) Upgrade the cursor initialization and destruction to
** account for fulltextFilter() being called multiple times on the
** same cursor. The current solution is very fragile. Apply fix to
** fts2 as appropriate.
*/
static int fulltextFilter(
sqlite3_vtab_cursor *pCursor, /* The cursor used for this query */
int idxNum, const char *idxStr, /* Which indexing scheme to use */
int argc, sqlite3_value **argv /* Arguments for the indexing scheme */
){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
fulltext_vtab *v = cursor_vtab(c);
int rc;
char *zSql;
TRACE(("FTS1 Filter %p\n",pCursor));
zSql = sqlite3_mprintf("select rowid, * from %%_content %s",
idxNum==QUERY_GENERIC ? "" : "where rowid=?");
sqlite3_finalize(c->pStmt);
rc = sql_prepare(v->db, v->zDb, v->zName, &c->pStmt, zSql);
sqlite3_free(zSql);
if( rc!=SQLITE_OK ) return rc;
c->iCursorType = idxNum;
switch( idxNum ){
case QUERY_GENERIC:
break;
case QUERY_ROWID:
rc = sqlite3_bind_int64(c->pStmt, 1, sqlite3_value_int64(argv[0]));
if( rc!=SQLITE_OK ) return rc;
break;
default: /* full-text search */
{
const char *zQuery = (const char *)sqlite3_value_text(argv[0]);
DocList *pResult;
assert( idxNum<=QUERY_FULLTEXT+v->nColumn);
assert( argc==1 );
queryClear(&c->q);
rc = fulltextQuery(v, idxNum-QUERY_FULLTEXT, zQuery, -1, &pResult, &c->q);
if( rc!=SQLITE_OK ) return rc;
if( c->result.pDoclist!=NULL ) docListDelete(c->result.pDoclist);
readerInit(&c->result, pResult);
break;
}
}
return fulltextNext(pCursor);
}
/* This is the xEof method of the virtual table. The SQLite core
** calls this routine to find out if it has reached the end of
** a query's results set.
*/
static int fulltextEof(sqlite3_vtab_cursor *pCursor){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
return c->eof;
}
/* This is the xColumn method of the virtual table. The SQLite
** core calls this method during a query when it needs the value
** of a column from the virtual table. This method needs to use
** one of the sqlite3_result_*() routines to store the requested
** value back in the pContext.
*/
static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
sqlite3_context *pContext, int idxCol){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
fulltext_vtab *v = cursor_vtab(c);
if( idxCol<v->nColumn ){
sqlite3_value *pVal = sqlite3_column_value(c->pStmt, idxCol+1);
sqlite3_result_value(pContext, pVal);
}else if( idxCol==v->nColumn ){
/* The extra column whose name is the same as the table.
** Return a blob which is a pointer to the cursor
*/
sqlite3_result_blob(pContext, &c, sizeof(c), SQLITE_TRANSIENT);
}
return SQLITE_OK;
}
/* This is the xRowid method. The SQLite core calls this routine to
** retrive the rowid for the current row of the result set. The
** rowid should be written to *pRowid.
*/
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;
}
/* Add all terms in [zText] to the given hash table. If [iColumn] > 0,
* we also store positions and offsets in the hash table using the given
* column number. */
static int buildTerms(fulltext_vtab *v, fts1Hash *terms, sqlite_int64 iDocid,
const char *zText, int iColumn){
sqlite3_tokenizer *pTokenizer = v->pTokenizer;
sqlite3_tokenizer_cursor *pCursor;
const char *pToken;
int nTokenBytes;
int iStartOffset, iEndOffset, iPosition;
int rc;
rc = pTokenizer->pModule->xOpen(pTokenizer, zText, -1, &pCursor);
if( rc!=SQLITE_OK ) return rc;
pCursor->pTokenizer = pTokenizer;
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 ){
pTokenizer->pModule->xClose(pCursor);
return SQLITE_ERROR;
}
p = fts1HashFind(terms, pToken, nTokenBytes);<