--- /dev/null
+/* 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 FTS2 module is being built as an extension
+** (in which case SQLITE_CORE is not defined), or
+**
+** * The FTS2 module is being built into the core of
+** SQLite (in which case SQLITE_ENABLE_FTS2 is defined).
+*/
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS2)
+
+#if defined(SQLITE_ENABLE_FTS2) && !defined(SQLITE_CORE)
+# define SQLITE_CORE 1
+#endif
+
+#include <assert.h>
+#if !defined(__APPLE__)
+#include <malloc.h>
+#else
+#include <stdlib.h>
+#endif
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "fts2.h"
+#include "fts2_hash.h"
+#include "fts2_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;
+
+void initStringBuffer(StringBuffer *sb){
+ sb->len = 0;
+ sb->alloced = 100;
+ sb->s = malloc(100);
+ sb->s[0] = '\0';
+}
+
+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;
+}
+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.
+*/
+
+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's 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
+ * 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 *zName){
+ const char *p;
+ size_t len = 0;
+ size_t nName = strlen(zName);
+ char *result;
+ char *r;
+
+ /* first compute length needed */
+ for(p = zFormat ; *p ; ++p){
+ len += (*p=='%' ? nName : 1);
+ }
+ len += 1; /* for null terminator */
+
+ r = result = malloc(len);
+ for(p = zFormat; *p; ++p){
+ if( *p=='%' ){
+ 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 *zName, const char *zFormat){
+ char *zCommand = string_format(zFormat, zName);
+ int rc;
+ TRACE(("FTS2 sql: %s\n", zCommand));
+ 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;
+ TRACE(("FTS2 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 *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->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 ){
+ 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, ...) 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);
+}
+
+void freeStringArray(int nString, const char **pString){
+ int i;
+
+ for (i=0 ; i < nString ; ++i) {
+ 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.
+ *
+ * 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){
+ 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(("FTS2 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; isspace(z[i]); i++){}
+ *tokenType = TOKEN_SPACE;
+ return i;
+ }
+ 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
+*/
+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: [ ] ...
+*/
+void tokenListToIdList(char **azIn){
+ int i, j;
+ if( azIn ){
+ for(i=0, j=-1; azIn[i]; i++){
+ if( 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 i, n, ttype;
+ i = 0;
+ 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( isspace(*s) ){ s++; }
+ while( *t ){
+ if( tolower(*s++)!=tolower(*t++) ) return 0;
+ }
+ return *s!='_' && !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 *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
+*/
+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 fts2(subject, body, tokenize mytokenizer(myarg))
+ *
+ * We return parsed information in a TableSpec structure.
+ *
+ */
+int parseSpec(TableSpec *pSpec, int argc, const char *const*argv, char**pzErr){
+ int i, j, 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->zName = azArg[2];
+ pSpec->nColumn = 0;
+ pSpec->azColumn = azArg;
+ zTokenizer = "tokenize simple";
+ for(i=3, j=0; 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( !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->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") ){
+ sqlite3Fts2SimpleTokenizerModule(&m);
+ }else if( startsWith(spec->azTokenizer[0], "porter") ){
+ sqlite3Fts2PorterTokenizerModule(&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(("FTS2 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(("FTS2 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.zName, schema.s);
+ free(schema.s);
+ if( rc!=SQLITE_OK ) goto out;
+
+ rc = sql_exec(db, 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;
+
+ 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 */
+ } else if( pConstraint->iColumn>=0 &&
+ pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
+ /* full-text search */
+ pInfo->idxNum = QUERY_FULLTEXT + 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;
+ TRACE(("FTS2 BestIndex\n"));
+ return SQLITE_OK;
+}
+
+static int fulltextDisconnect(sqlite3_vtab *pVTab){
+ TRACE(("FTS2 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(("FTS2 Destroy %p\n", pVTab));
+ 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;
+ TRACE(("FTS2 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 FTS2_ROTOR_SZ (32)
+#define FTS2_ROTOR_MASK (FTS2_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[FTS2_ROTOR_SZ]; /* Beginning offset of token */
+ int iRotorLen[FTS2_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>=FTS2_ROTOR_SZ ){
+ nTerm = FTS2_ROTOR_SZ - 1;
+ }
+ prevMatch = 0;
+ while(1){
+ rc = pTModule->xNext(pTCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
+ if( rc ) break;
+ iRotorBegin[iRotor&FTS2_ROTOR_MASK] = iBegin;
+ iRotorLen[iRotor&FTS2_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) & FTS2_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;
+ 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] = ' ';
+ sprintf(&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( isspace(zDoc[iBreak-i]) ){
+ return iBreak - i + 1;
+ }
+ if( 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( 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 && 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(("FTS2 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(("FTS2 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 ) 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.
+*/
+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(("FTS2 Filter %p\n",pCursor));
+
+ zSql = sqlite3_mprintf("select rowid, * from %%_content %s",
+ idxNum==QUERY_GENERIC ? "" : "where rowid=?");
+ rc = sql_prepare(v->db, v->zName, &c->pStmt, zSql);
+ sqlite3_free(zSql);
+ if( rc!=SQLITE_OK ) goto out;
+
+ 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 ) goto out;
+ 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 ) goto out;
+ readerInit(&c->result, pResult);
+ break;
+ }
+ }
+
+ rc = fulltextNext(pCursor);
+
+out:
+ return rc;
+}
+
+/* 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, fts2Hash *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 = fts2HashFind(terms, pToken, nTokenBytes);
+ if( p==NULL ){
+ p = docListNew(DL_DEFAULT);
+ docListAddDocid(p, iDocid);
+ fts2HashInsert(terms, pToken, nTokenBytes, p);
+ }
+ if( iColumn>=0 ){
+ docListAddPosOffset(p, iColumn, iPosition, iStartOffset, iEndOffset);
+ }
+ }
+
+ /* 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 [pTerm] to the given rowid. */
+static int index_insert_term(fulltext_vtab *v, const char *pTerm, int nTerm,
+ DocList *d){
+ sqlite_int64 iIndexRow;
+ DocList doclist;
+ int iSegment = 0, rc;
+
+ rc = term_select(v, pTerm, nTerm, iSegment, &iIndexRow, &doclist);
+ if( rc==SQLITE_DONE ){
+ docListInit(&doclist, DL_DEFAULT, 0, 0);
+ docListUpdate(&doclist, d);
+ /* TODO(shess) Consider length(doclist)>CHUNK_MAX? */
+ rc = term_insert(v, NULL, pTerm, nTerm, iSegment, &doclist);
+ goto err;
+ }
+ if( rc!=SQLITE_ROW ) return SQLITE_ERROR;
+
+ docListUpdate(&doclist, d);
+ if( doclist.nData<=CHUNK_MAX ){
+ rc = term_update(v, iIndexRow, &doclist);
+ goto err;
+ }
+
+ /* Doclist doesn't fit, delete what's there, and accumulate
+ ** forward.
+ */
+ rc = term_delete(v, iIndexRow);
+ if( rc!=SQLITE_OK ) goto err;
+
+ /* Try to insert the doclist into a higher segment bucket. On
+ ** failure, accumulate existing doclist with the doclist from that
+ ** bucket, and put results in the next bucket.
+ */
+ iSegment++;
+ while( (rc=term_insert(v, &iIndexRow, pTerm, nTerm, iSegment,
+ &doclist))!=SQLITE_OK ){
+ sqlite_int64 iSegmentRow;
+ DocList old;
+ int rc2;
+
+ /* Retain old error in case the term_insert() error was really an
+ ** error rather than a bounced insert.
+ */
+ rc2 = term_select(v, pTerm, nTerm, iSegment, &iSegmentRow, &old);
+ if( rc2!=SQLITE_ROW ) goto err;
+
+ rc = term_delete(v, iSegmentRow);
+ if( rc!=SQLITE_OK ) goto err;
+
+ /* Reusing lowest-number deleted row keeps the index smaller. */
+ if( iSegmentRow<iIndexRow ) iIndexRow = iSegmentRow;
+
+ /* doclist contains the newer data, so accumulate it over old.
+ ** Then steal accumulated data for doclist.
+ */
+ docListAccumulate(&old, &doclist);
+ docListDestroy(&doclist);
+ doclist = old;
+
+ iSegment++;
+ }
+
+ err:
+ docListDestroy(&doclist);
+ return rc;
+}
+
+/* Add doclists for all terms in [pValues] to the hash table [terms]. */
+static int insertTerms(fulltext_vtab *v, fts2Hash *terms, sqlite_int64 iRowid,
+ sqlite3_value **pValues){
+ int i;
+ for(i = 0; i < v->nColumn ; ++i){
+ char *zText = (char*)sqlite3_value_text(pValues[i]);
+ int rc = buildTerms(v, terms, iRowid, zText, i);
+ if( rc!=SQLITE_OK ) return rc;
+ }
+ return SQLITE_OK;
+}
+
+/* Add empty doclists for all terms in the given row's content to the hash
+ * table [pTerms]. */
+static int deleteTerms(fulltext_vtab *v, fts2Hash *pTerms, sqlite_int64 iRowid){
+ const char **pValues;
+ int i;
+
+ int rc = content_select(v, iRowid, &pValues);
+ if( rc!=SQLITE_OK ) return rc;
+
+ for(i = 0 ; i < v->nColumn; ++i) {
+ rc = buildTerms(v, pTerms, iRowid, pValues[i], -1);
+ if( rc!=SQLITE_OK ) break;
+ }
+
+ freeStringArray(v->nColumn, pValues);
+ return SQLITE_OK;
+}
+
+/* Insert a row into the %_content table; set *piRowid to be the ID of the
+ * new row. Fill [pTerms] with new doclists for the %_term table. */
+static int index_insert(fulltext_vtab *v, sqlite3_value *pRequestRowid,
+ sqlite3_value **pValues,
+ sqlite_int64 *piRowid, fts2Hash *pTerms){
+ int rc;
+
+ rc = content_insert(v, pRequestRowid, pValues); /* execute an SQL INSERT */
+ if( rc!=SQLITE_OK ) return rc;
+ *piRowid = sqlite3_last_insert_rowid(v->db);
+ return insertTerms(v, pTerms, *piRowid, pValues);
+}
+
+/* Delete a row from the %_content table; fill [pTerms] with empty doclists
+ * to be written to the %_term table. */
+static int index_delete(fulltext_vtab *v, sqlite_int64 iRow, fts2Hash *pTerms){
+ int rc = deleteTerms(v, pTerms, iRow);
+ if( rc!=SQLITE_OK ) return rc;
+ return content_delete(v, iRow); /* execute an SQL DELETE */
+}
+
+/* Update a row in the %_content table; fill [pTerms] with new doclists for the
+ * %_term table. */
+static int index_update(fulltext_vtab *v, sqlite_int64 iRow,
+ sqlite3_value **pValues, fts2Hash *pTerms){
+ /* Generate an empty doclist for each term that previously appeared in this
+ * row. */
+ int rc = deleteTerms(v, pTerms, iRow);
+ if( rc!=SQLITE_OK ) return rc;
+
+ /* Now add positions for terms which appear in the updated row. */
+ rc = insertTerms(v, pTerms, iRow, pValues);
+ if( rc!=SQLITE_OK ) return rc;
+
+ return content_update(v, pValues, iRow); /* execute an SQL UPDATE */
+}
+
+/* This function implements the xUpdate callback; it's the top-level entry
+ * point for inserting, deleting or updating a row in a full-text table. */
+static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
+ sqlite_int64 *pRowid){
+ fulltext_vtab *v = (fulltext_vtab *) pVtab;
+ fts2Hash terms; /* maps term string -> PosList */
+ int rc;
+ fts2HashElem *e;
+
+ TRACE(("FTS2 Update %p\n", pVtab));
+
+ fts2HashInit(&terms, FTS2_HASH_STRING, 1);
+
+ if( nArg<2 ){
+ rc = index_delete(v, sqlite3_value_int64(ppArg[0]), &terms);
+ } else if( sqlite3_value_type(ppArg[0]) != SQLITE_NULL ){
+ /* An update:
+ * ppArg[0] = old rowid
+ * ppArg[1] = new rowid
+ * ppArg[2..2+v->nColumn-1] = values
+ * ppArg[2+v->nColumn] = value for magic column (we ignore this)
+ */
+ sqlite_int64 rowid = sqlite3_value_int64(ppArg[0]);
+ if( sqlite3_value_type(ppArg[1]) != SQLITE_INTEGER ||
+ sqlite3_value_int64(ppArg[1]) != rowid ){
+ rc = SQLITE_ERROR; /* we don't allow changing the rowid */
+ } else {
+ assert( nArg==2+v->nColumn+1);
+ rc = index_update(v, rowid, &ppArg[2], &terms);
+ }
+ } else {
+ /* An insert:
+ * ppArg[1] = requested rowid
+ * ppArg[2..2+v->nColumn-1] = values
+ * ppArg[2+v->nColumn] = value for magic column (we ignore this)
+ */
+ assert( nArg==2+v->nColumn+1);
+ rc = index_insert(v, ppArg[1], &ppArg[2], pRowid, &terms);
+ }
+
+ if( rc==SQLITE_OK ){
+ /* Write updated doclists to disk. */
+ for(e=fts2HashFirst(&terms); e; e=fts2HashNext(e)){
+ DocList *p = fts2HashData(e);
+ rc = index_insert_term(v, fts2HashKey(e), fts2HashKeysize(e), p);
+ if( rc!=SQLITE_OK ) break;
+ }
+ }
+
+ /* clean up */
+ for(e=fts2HashFirst(&terms); e; e=fts2HashNext(e)){
+ DocList *p = fts2HashData(e);
+ docListDelete(p);
+ }
+ fts2HashClear(&terms);
+
+ return rc;
+}
+
+/*
+** Implementation of the snippet() function for FTS2
+*/
+static void snippetFunc(
+ sqlite3_context *pContext,
+ int argc,
+ sqlite3_value **argv
+){
+ fulltext_cursor *pCursor;
+ if( argc<1 ) return;
+ if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
+ sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
+ sqlite3_result_error(pContext, "illegal first argument to html_snippet",-1);
+ }else{
+ const char *zStart = "<b>";
+ const char *zEnd = "</b>";
+ const char *zEllipsis = "<b>...</b>";
+ memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
+ if( argc>=2 ){
+ zStart = (const char*)sqlite3_value_text(argv[1]);
+ if( argc>=3 ){
+ zEnd = (const char*)sqlite3_value_text(argv[2]);
+ if( argc>=4 ){
+ zEllipsis = (const char*)sqlite3_value_text(argv[3]);
+ }
+ }
+ }
+ snippetAllOffsets(pCursor);
+ snippetText(pCursor, zStart, zEnd, zEllipsis);
+ sqlite3_result_text(pContext, pCursor->snippet.zSnippet,
+ pCursor->snippet.nSnippet, SQLITE_STATIC);
+ }
+}
+
+/*
+** Implementation of the offsets() function for FTS2
+*/
+static void snippetOffsetsFunc(
+ sqlite3_context *pContext,
+ int argc,
+ sqlite3_value **argv
+){
+ fulltext_cursor *pCursor;
+ if( argc<1 ) return;
+ if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
+ sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
+ sqlite3_result_error(pContext, "illegal first argument to offsets",-1);
+ }else{
+ memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
+ snippetAllOffsets(pCursor);
+ snippetOffsetText(&pCursor->snippet);
+ sqlite3_result_text(pContext,
+ pCursor->snippet.zOffset, pCursor->snippet.nOffset,
+ SQLITE_STATIC);
+ }
+}
+
+/*
+** This routine implements the xFindFunction method for the FTS2
+** virtual table.
+*/
+static int fulltextFindFunction(
+ sqlite3_vtab *pVtab,
+ int nArg,
+ const char *zName,
+ void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+ void **ppArg
+){
+ if( strcmp(zName,"snippet")==0 ){
+ *pxFunc = snippetFunc;
+ return 1;
+ }else if( strcmp(zName,"offsets")==0 ){
+ *pxFunc = snippetOffsetsFunc;
+ return 1;
+ }
+ return 0;
+}
+
+static const sqlite3_module fulltextModule = {
+ /* iVersion */ 0,
+ /* xCreate */ fulltextCreate,
+ /* xConnect */ fulltextConnect,
+ /* xBestIndex */ fulltextBestIndex,
+ /* xDisconnect */ fulltextDisconnect,
+ /* xDestroy */ fulltextDestroy,
+ /* xOpen */ fulltextOpen,
+ /* xClose */ fulltextClose,
+ /* xFilter */ fulltextFilter,
+ /* xNext */ fulltextNext,
+ /* xEof */ fulltextEof,
+ /* xColumn */ fulltextColumn,
+ /* xRowid */ fulltextRowid,
+ /* xUpdate */ fulltextUpdate,
+ /* xBegin */ 0,
+ /* xSync */ 0,
+ /* xCommit */ 0,
+ /* xRollback */ 0,
+ /* xFindFunction */ fulltextFindFunction,
+};
+
+int sqlite3Fts2Init(sqlite3 *db){
+ sqlite3_overload_function(db, "snippet", -1);
+ sqlite3_overload_function(db, "offsets", -1);
+ return sqlite3_create_module(db, "fts2", &fulltextModule, 0);
+}
+
+#if !SQLITE_CORE
+int sqlite3_extension_init(sqlite3 *db, char **pzErrMsg,
+ const sqlite3_api_routines *pApi){
+ SQLITE_EXTENSION_INIT2(pApi)
+ return sqlite3Fts2Init(db);
+}
+#endif
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS2) */
projects / thirdparty / sqlite.git / commitdiff
