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freeswitch/libs/sqlite/ext/fts2/fts2.c

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/* 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).
*/
/* TODO(shess) Consider exporting this comment to an HTML file or the
** wiki.
*/
/* The full-text index is stored in a series of b+tree (-like)
** structures called segments which map terms to doclists. The
** structures are like b+trees in layout, but are constructed from the
** bottom up in optimal fashion and are not updatable. Since trees
** are built from the bottom up, things will be described from the
** bottom up.
**
**
**** Varints ****
** The basic unit of encoding is a variable-length integer called a
** varint. 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.
**
** This is identical to how sqlite encodes varints (see util.c).
**
**
**** Document lists ****
** A doclist (document list) holds a docid-sorted list of hits for a
** given term. Doclists hold docids, and can optionally associate
** token positions and offsets with docids.
**
** A DL_POSITIONS_OFFSETS doclist is stored like this:
**
** array {
** varint docid;
** array { (position list for column 0)
** varint position; (delta from previous position plus POS_BASE)
** varint startOffset; (delta from previous startOffset)
** varint endOffset; (delta from startOffset)
** }
** array {
** varint POS_COLUMN; (marks start of position list for new column)
** varint column; (index of new column)
** array {
** varint position; (delta from previous position plus POS_BASE)
** varint startOffset;(delta from previous startOffset)
** varint endOffset; (delta from startOffset)
** }
** }
** varint POS_END; (marks end of positions for this document.
** }
**
** Here, array { X } means zero or more occurrences of X, adjacent in
** memory. A "position" is an index of a token in the token stream
** generated by the tokenizer, while an "offset" is a byte offset,
** both based at 0. Note that POS_END and POS_COLUMN occur in the
** same logical place as the position element, and act as sentinals
** ending a position list array.
**
** A DL_POSITIONS doclist omits the startOffset and endOffset
** information. A DL_DOCIDS doclist omits both the position and
** offset information, becoming an array of varint-encoded docids.
**
** On-disk data is stored as type DL_DEFAULT, so we don't serialize
** the type. Due to how deletion is implemented in the segmentation
** system, on-disk doclists MUST store at least positions.
**
**
**** Segment leaf nodes ****
** Segment leaf nodes store terms and doclists, ordered by term. Leaf
** nodes are written using LeafWriter, and read using LeafReader (to
** iterate through a single leaf node's data) and LeavesReader (to
** iterate through a segment's entire leaf layer). Leaf nodes have
** the format:
**
** varint iHeight; (height from leaf level, always 0)
** varint nTerm; (length of first term)
** char pTerm[nTerm]; (content of first term)
** varint nDoclist; (length of term's associated doclist)
** char pDoclist[nDoclist]; (content of doclist)
** array {
** (further terms are delta-encoded)
** varint nPrefix; (length of prefix shared with previous term)
** varint nSuffix; (length of unshared suffix)
** char pTermSuffix[nSuffix];(unshared suffix of next term)
** varint nDoclist; (length of term's associated doclist)
** char pDoclist[nDoclist]; (content of doclist)
** }
**
** Here, array { X } means zero or more occurrences of X, adjacent in
** memory.
**
** Leaf nodes are broken into blocks which are stored contiguously in
** the %_segments table in sorted order. This means that when the end
** of a node is reached, the next term is in the node with the next
** greater node id.
**
** New data is spilled to a new leaf node when the current node
** exceeds LEAF_MAX bytes (default 2048). New data which itself is
** larger than STANDALONE_MIN (default 1024) is placed in a standalone
** node (a leaf node with a single term and doclist). The goal of
** these settings is to pack together groups of small doclists while
** making it efficient to directly access large doclists. The
** assumption is that large doclists represent terms which are more
** likely to be query targets.
**
** TODO(shess) It may be useful for blocking decisions to be more
** dynamic. For instance, it may make more sense to have a 2.5k leaf
** node rather than splitting into 2k and .5k nodes. My intuition is
** that this might extend through 2x or 4x the pagesize.
**
**
**** Segment interior nodes ****
** Segment interior nodes store blockids for subtree nodes and terms
** to describe what data is stored by the each subtree. Interior
** nodes are written using InteriorWriter, and read using
** InteriorReader. InteriorWriters are created as needed when
** SegmentWriter creates new leaf nodes, or when an interior node
** itself grows too big and must be split. The format of interior
** nodes:
**
** varint iHeight; (height from leaf level, always >0)
** varint iBlockid; (block id of node's leftmost subtree)
** optional {
** varint nTerm; (length of first term)
** char pTerm[nTerm]; (content of first term)
** array {
** (further terms are delta-encoded)
** varint nPrefix; (length of shared prefix with previous term)
** varint nSuffix; (length of unshared suffix)
** char pTermSuffix[nSuffix]; (unshared suffix of next term)
** }
** }
**
** Here, optional { X } means an optional element, while array { X }
** means zero or more occurrences of X, adjacent in memory.
**
** An interior node encodes n terms separating n+1 subtrees. The
** subtree blocks are contiguous, so only the first subtree's blockid
** is encoded. The subtree at iBlockid will contain all terms less
** than the first term encoded (or all terms if no term is encoded).
** Otherwise, for terms greater than or equal to pTerm[i] but less
** than pTerm[i+1], the subtree for that term will be rooted at
** iBlockid+i. Interior nodes only store enough term data to
** distinguish adjacent children (if the rightmost term of the left
** child is "something", and the leftmost term of the right child is
** "wicked", only "w" is stored).
**
** New data is spilled to a new interior node at the same height when
** the current node exceeds INTERIOR_MAX bytes (default 2048).
** INTERIOR_MIN_TERMS (default 7) keeps large terms from monopolizing
** interior nodes and making the tree too skinny. The interior nodes
** at a given height are naturally tracked by interior nodes at
** height+1, and so on.
**
**
**** Segment directory ****
** The segment directory in table %_segdir stores meta-information for
** merging and deleting segments, and also the root node of the
** segment's tree.
**
** The root node is the top node of the segment's tree after encoding
** the entire segment, restricted to ROOT_MAX bytes (default 1024).
** This could be either a leaf node or an interior node. If the top
** node requires more than ROOT_MAX bytes, it is flushed to %_segments
** and a new root interior node is generated (which should always fit
** within ROOT_MAX because it only needs space for 2 varints, the
** height and the blockid of the previous root).
**
** The meta-information in the segment directory is:
** level - segment level (see below)
** idx - index within level
** - (level,idx uniquely identify a segment)
** start_block - first leaf node
** leaves_end_block - last leaf node
** end_block - last block (including interior nodes)
** root - contents of root node
**
** If the root node is a leaf node, then start_block,
** leaves_end_block, and end_block are all 0.
**
**
**** Segment merging ****
** To amortize update costs, segments are groups into levels and
** merged in matches. Each increase in level represents exponentially
** more documents.
**
** New documents (actually, document updates) are tokenized and
** written individually (using LeafWriter) to a level 0 segment, with
** incrementing idx. When idx reaches MERGE_COUNT (default 16), all
** level 0 segments are merged into a single level 1 segment. Level 1
** is populated like level 0, and eventually MERGE_COUNT level 1
** segments are merged to a single level 2 segment (representing
** MERGE_COUNT^2 updates), and so on.
**
** A segment merge traverses all segments at a given level in
** parallel, performing a straightforward sorted merge. Since segment
** leaf nodes are written in to the %_segments table in order, this
** merge traverses the underlying sqlite disk structures efficiently.
** After the merge, all segment blocks from the merged level are
** deleted.
**
** MERGE_COUNT controls how often we merge segments. 16 seems to be
** somewhat of a sweet spot for insertion performance. 32 and 64 show
** very similar performance numbers to 16 on insertion, though they're
** a tiny bit slower (perhaps due to more overhead in merge-time
** sorting). 8 is about 20% slower than 16, 4 about 50% slower than
** 16, 2 about 66% slower than 16.
**
** At query time, high MERGE_COUNT increases the number of segments
** which need to be scanned and merged. For instance, with 100k docs
** inserted:
**
** MERGE_COUNT segments
** 16 25
** 8 12
** 4 10
** 2 6
**
** This appears to have only a moderate impact on queries for very
** frequent terms (which are somewhat dominated by segment merge
** costs), and infrequent and non-existent terms still seem to be fast
** even with many segments.
**
** TODO(shess) That said, it would be nice to have a better query-side
** argument for MERGE_COUNT of 16. Also, it's possible/likely that
** optimizations to things like doclist merging will swing the sweet
** spot around.
**
**
**
**** Handling of deletions and updates ****
** Since we're using a segmented structure, with no docid-oriented
** index into the term index, we clearly cannot simply update the term
** index when a document is deleted or updated. For deletions, we
** write an empty doclist (varint(docid) varint(POS_END)), for updates
** we simply write the new doclist. Segment merges overwrite older
** data for a particular docid with newer data, so deletes or updates
** will eventually overtake the earlier data and knock it out. The
** query logic likewise merges doclists so that newer data knocks out
** older data.
**
** TODO(shess) Provide a VACUUM type operation to clear out all
** deletions and duplications. This would basically be a forced merge
** into a single segment.
*/
#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>
#endif
#include <stdlib.h>
#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
/* TODO(shess) MAN, this thing needs some refactoring. At minimum, it
** would be nice to order the file better, perhaps something along the
** lines of:
**
** - utility functions
** - table setup functions
** - table update functions
** - table query functions
**
** Put the query functions last because they're likely to reference
** typedefs or functions from the table update section.
*/
#if 0
# define TRACE(A) printf A; fflush(stdout)
#else
# define TRACE(A)
#endif
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
**
** If DL_DEFAULT is set to DL_DOCIDS, your table can only be inserted
** into (no deletes or updates).
*/
#ifndef DL_DEFAULT
# define DL_DEFAULT DL_POSITIONS
#endif
enum {
POS_END = 0, /* end of this position list */
POS_COLUMN, /* followed by new column number */
POS_BASE
};
/* MERGE_COUNT controls how often we merge segments (see comment at
** top of file).
*/
#define MERGE_COUNT 16
/* utility functions */
/* CLEAR() and SCRAMBLE() abstract memset() on a pointer to a single
** record to prevent errors of the form:
**
** my_function(SomeType *b){
** memset(b, '\0', sizeof(b)); // sizeof(b)!=sizeof(*b)
** }
*/
/* TODO(shess) Obvious candidates for a header file. */
#define CLEAR(b) memset(b, '\0', sizeof(*(b)))
#ifndef NDEBUG
# define SCRAMBLE(b) memset(b, 0x55, sizeof(*(b)))
#else
# define SCRAMBLE(b)
#endif
/* 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;
}
/*******************************************************************/
/* DataBuffer is used to collect data into a buffer in piecemeal
** fashion. It implements the usual distinction between amount of
** data currently stored (nData) and buffer capacity (nCapacity).
**
** dataBufferInit - create a buffer with given initial capacity.
** dataBufferReset - forget buffer's data, retaining capacity.
** dataBufferDestroy - free buffer's data.
** dataBufferExpand - expand capacity without adding data.
** dataBufferAppend - append data.
** dataBufferAppend2 - append two pieces of data at once.
** dataBufferReplace - replace buffer's data.
*/
typedef struct DataBuffer {
char *pData; /* Pointer to malloc'ed buffer. */
int nCapacity; /* Size of pData buffer. */
int nData; /* End of data loaded into pData. */
} DataBuffer;
static void dataBufferInit(DataBuffer *pBuffer, int nCapacity){
assert( nCapacity>=0 );
pBuffer->nData = 0;
pBuffer->nCapacity = nCapacity;
pBuffer->pData = nCapacity==0 ? NULL : malloc(nCapacity);
}
static void dataBufferReset(DataBuffer *pBuffer){
pBuffer->nData = 0;
}
static void dataBufferDestroy(DataBuffer *pBuffer){
if( pBuffer->pData!=NULL ) free(pBuffer->pData);
SCRAMBLE(pBuffer);
}
static void dataBufferExpand(DataBuffer *pBuffer, int nAddCapacity){
assert( nAddCapacity>0 );
/* TODO(shess) Consider expanding more aggressively. Note that the
** underlying malloc implementation may take care of such things for
** us already.
*/
if( pBuffer->nData+nAddCapacity>pBuffer->nCapacity ){
pBuffer->nCapacity = pBuffer->nData+nAddCapacity;
pBuffer->pData = realloc(pBuffer->pData, pBuffer->nCapacity);
}
}
static void dataBufferAppend(DataBuffer *pBuffer,
const char *pSource, int nSource){
assert( nSource>0 && pSource!=NULL );
dataBufferExpand(pBuffer, nSource);
memcpy(pBuffer->pData+pBuffer->nData, pSource, nSource);
pBuffer->nData += nSource;
}
static void dataBufferAppend2(DataBuffer *pBuffer,
const char *pSource1, int nSource1,
const char *pSource2, int nSource2){
assert( nSource1>0 && pSource1!=NULL );
assert( nSource2>0 && pSource2!=NULL );
dataBufferExpand(pBuffer, nSource1+nSource2);
memcpy(pBuffer->pData+pBuffer->nData, pSource1, nSource1);
memcpy(pBuffer->pData+pBuffer->nData+nSource1, pSource2, nSource2);
pBuffer->nData += nSource1+nSource2;
}
static void dataBufferReplace(DataBuffer *pBuffer,
const char *pSource, int nSource){
dataBufferReset(pBuffer);
dataBufferAppend(pBuffer, pSource, nSource);
}
/* StringBuffer is a null-terminated version of DataBuffer. */
typedef struct StringBuffer {
DataBuffer b; /* Includes null terminator. */
} StringBuffer;
static void initStringBuffer(StringBuffer *sb){
dataBufferInit(&sb->b, 100);
dataBufferReplace(&sb->b, "", 1);
}
static int stringBufferLength(StringBuffer *sb){
return sb->b.nData-1;
}
static char *stringBufferData(StringBuffer *sb){
return sb->b.pData;
}
static void stringBufferDestroy(StringBuffer *sb){
dataBufferDestroy(&sb->b);
}
static void nappend(StringBuffer *sb, const char *zFrom, int nFrom){
assert( sb->b.nData>0 );
if( nFrom>0 ){
sb->b.nData--;
dataBufferAppend2(&sb->b, zFrom, nFrom, "", 1);
}
}
static void append(StringBuffer *sb, const char *zFrom){
nappend(sb, zFrom, strlen(zFrom));
}
/* Append a list of strings separated by commas. */
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]);
}
}
static int endsInWhiteSpace(StringBuffer *p){
return stringBufferLength(p)>0 &&
isspace(stringBufferData(p)[stringBufferLength(p)-1]);
}
/* If the StringBuffer ends in something other than white space, add a
** single space character to the end.
*/
static void appendWhiteSpace(StringBuffer *p){
if( stringBufferLength(p)==0 ) return;
if( !endsInWhiteSpace(p) ) append(p, " ");
}
/* Remove white space from the end of the StringBuffer */
static void trimWhiteSpace(StringBuffer *p){
while( endsInWhiteSpace(p) ){
p->b.pData[--p->b.nData-1] = '\0';
}
}
/*******************************************************************/
/* DLReader is used to read document elements from a doclist. The
** current docid is cached, so dlrDocid() is fast. DLReader does not
** own the doclist buffer.
**
** dlrAtEnd - true if there's no more data to read.
** dlrDocid - docid of current document.
** dlrDocData - doclist data for current document (including docid).
** dlrDocDataBytes - length of same.
** dlrAllDataBytes - length of all remaining data.
** dlrPosData - position data for current document.
** dlrPosDataLen - length of pos data for current document (incl POS_END).
** dlrStep - step to current document.
** dlrInit - initial for doclist of given type against given data.
** dlrDestroy - clean up.
**
** Expected usage is something like:
**
** DLReader reader;
** dlrInit(&reader, pData, nData);
** while( !dlrAtEnd(&reader) ){
** // calls to dlrDocid() and kin.
** dlrStep(&reader);
** }
** dlrDestroy(&reader);
*/
typedef struct DLReader {
DocListType iType;
const char *pData;
int nData;
sqlite_int64 iDocid;
int nElement;
} DLReader;
static int dlrAtEnd(DLReader *pReader){
assert( pReader->nData>=0 );
return pReader->nData==0;
}
static sqlite_int64 dlrDocid(DLReader *pReader){
assert( !dlrAtEnd(pReader) );
return pReader->iDocid;
}
static const char *dlrDocData(DLReader *pReader){
assert( !dlrAtEnd(pReader) );
return pReader->pData;
}
static int dlrDocDataBytes(DLReader *pReader){
assert( !dlrAtEnd(pReader) );
return pReader->nElement;
}
static int dlrAllDataBytes(DLReader *pReader){
assert( !dlrAtEnd(pReader) );
return pReader->nData;
}
/* TODO(shess) Consider adding a field to track iDocid varint length
** to make these two functions faster. This might matter (a tiny bit)
** for queries.
*/
static const char *dlrPosData(DLReader *pReader){
sqlite_int64 iDummy;
int n = getVarint(pReader->pData, &iDummy);
assert( !dlrAtEnd(pReader) );
return pReader->pData+n;
}
static int dlrPosDataLen(DLReader *pReader){
sqlite_int64 iDummy;
int n = getVarint(pReader->pData, &iDummy);
assert( !dlrAtEnd(pReader) );
return pReader->nElement-n;
}
static void dlrStep(DLReader *pReader){
assert( !dlrAtEnd(pReader) );
/* Skip past current doclist element. */
assert( pReader->nElement<=pReader->nData );
pReader->pData += pReader->nElement;
pReader->nData -= pReader->nElement;
/* If there is more data, read the next doclist element. */
if( pReader->nData!=0 ){
sqlite_int64 iDocidDelta;
int iDummy, n = getVarint(pReader->pData, &iDocidDelta);
pReader->iDocid += iDocidDelta;
if( pReader->iType>=DL_POSITIONS ){
assert( n<pReader->nData );
while( 1 ){
n += getVarint32(pReader->pData+n, &iDummy);
assert( n<=pReader->nData );
if( iDummy==POS_END ) break;
if( iDummy==POS_COLUMN ){
n += getVarint32(pReader->pData+n, &iDummy);
assert( n<pReader->nData );
}else if( pReader->iType==DL_POSITIONS_OFFSETS ){
n += getVarint32(pReader->pData+n, &iDummy);
n += getVarint32(pReader->pData+n, &iDummy);
assert( n<pReader->nData );
}
}
}
pReader->nElement = n;
assert( pReader->nElement<=pReader->nData );
}
}
static void dlrInit(DLReader *pReader, DocListType iType,
const char *pData, int nData){
assert( pData!=NULL && nData!=0 );
pReader->iType = iType;
pReader->pData = pData;
pReader->nData = nData;
pReader->nElement = 0;
pReader->iDocid = 0;
/* Load the first element's data. There must be a first element. */
dlrStep(pReader);
}
static void dlrDestroy(DLReader *pReader){
SCRAMBLE(pReader);
}
#ifndef NDEBUG
/* Verify that the doclist can be validly decoded. Also returns the
** last docid found because it's convenient in other assertions for
** DLWriter.
*/
static void docListValidate(DocListType iType, const char *pData, int nData,
sqlite_int64 *pLastDocid){
sqlite_int64 iPrevDocid = 0;
assert( nData>0 );
assert( pData!=0 );
assert( pData+nData>pData );
while( nData!=0 ){
sqlite_int64 iDocidDelta;
int n = getVarint(pData, &iDocidDelta);
iPrevDocid += iDocidDelta;
if( iType>DL_DOCIDS ){
int iDummy;
while( 1 ){
n += getVarint32(pData+n, &iDummy);
if( iDummy==POS_END ) break;
if( iDummy==POS_COLUMN ){
n += getVarint32(pData+n, &iDummy);
}else if( iType>DL_POSITIONS ){
n += getVarint32(pData+n, &iDummy);
n += getVarint32(pData+n, &iDummy);
}
assert( n<=nData );
}
}
assert( n<=nData );
pData += n;
nData -= n;
}
if( pLastDocid ) *pLastDocid = iPrevDocid;
}
#define ASSERT_VALID_DOCLIST(i, p, n, o) docListValidate(i, p, n, o)
#else
#define ASSERT_VALID_DOCLIST(i, p, n, o) assert( 1 )
#endif
/*******************************************************************/
/* DLWriter is used to write doclist data to a DataBuffer. DLWriter
** always appends to the buffer and does not own it.
**
** dlwInit - initialize to write a given type doclistto a buffer.
** dlwDestroy - clear the writer's memory. Does not free buffer.
** dlwAppend - append raw doclist data to buffer.
** dlwAdd - construct doclist element and append to buffer.
*/
typedef struct DLWriter {
DocListType iType;
DataBuffer *b;
sqlite_int64 iPrevDocid;
} DLWriter;
static void dlwInit(DLWriter *pWriter, DocListType iType, DataBuffer *b){
pWriter->b = b;
pWriter->iType = iType;
pWriter->iPrevDocid = 0;
}
static void dlwDestroy(DLWriter *pWriter){
SCRAMBLE(pWriter);
}
/* iFirstDocid is the first docid in the doclist in pData. It is
** needed because pData may point within a larger doclist, in which
** case the first item would be delta-encoded.
**
** iLastDocid is the final docid in the doclist in pData. It is
** needed to create the new iPrevDocid for future delta-encoding. The
** code could decode the passed doclist to recreate iLastDocid, but
** the only current user (docListMerge) already has decoded this
** information.
*/
/* TODO(shess) This has become just a helper for docListMerge.
** Consider a refactor to make this cleaner.
*/
static void dlwAppend(DLWriter *pWriter,
const char *pData, int nData,
sqlite_int64 iFirstDocid, sqlite_int64 iLastDocid){
sqlite_int64 iDocid = 0;
char c[VARINT_MAX];
int nFirstOld, nFirstNew; /* Old and new varint len of first docid. */
#ifndef NDEBUG
sqlite_int64 iLastDocidDelta;
#endif
/* Recode the initial docid as delta from iPrevDocid. */
nFirstOld = getVarint(pData, &iDocid);
assert( nFirstOld<nData || (nFirstOld==nData && pWriter->iType==DL_DOCIDS) );
nFirstNew = putVarint(c, iFirstDocid-pWriter->iPrevDocid);
/* Verify that the incoming doclist is valid AND that it ends with
** the expected docid. This is essential because we'll trust this
** docid in future delta-encoding.
*/
ASSERT_VALID_DOCLIST(pWriter->iType, pData, nData, &iLastDocidDelta);
assert( iLastDocid==iFirstDocid-iDocid+iLastDocidDelta );
/* Append recoded initial docid and everything else. Rest of docids
** should have been delta-encoded from previous initial docid.
*/
if( nFirstOld<nData ){
dataBufferAppend2(pWriter->b, c, nFirstNew,
pData+nFirstOld, nData-nFirstOld);
}else{
dataBufferAppend(pWriter->b, c, nFirstNew);
}
pWriter->iPrevDocid = iLastDocid;
}
static void dlwAdd(DLWriter *pWriter, sqlite_int64 iDocid,
const char *pPosList, int nPosList){
char c[VARINT_MAX];
int n = putVarint(c, iDocid-pWriter->iPrevDocid);
assert( pWriter->iPrevDocid<iDocid );
assert( pPosList==0 || pWriter->iType>DL_DOCIDS );
dataBufferAppend(pWriter->b, c, n);
if( pWriter->iType>DL_DOCIDS ){
n = putVarint(c, 0);
if( nPosList>0 ){
dataBufferAppend2(pWriter->b, pPosList, nPosList, c, n);
}else{
dataBufferAppend(pWriter->b, c, n);
}
}
pWriter->iPrevDocid = iDocid;
}
/*******************************************************************/
/* PLReader is used to read data from a document's position list. As
** the caller steps through the list, data is cached so that varints
** only need to be decoded once.
**
** plrInit, plrDestroy - create/destroy a reader.
** plrColumn, plrPosition, plrStartOffset, plrEndOffset - accessors
** plrAtEnd - at end of stream, only call plrDestroy once true.
** plrStep - step to the next element.
*/
typedef struct PLReader {
/* These refer to the next position's data. nData will reach 0 when
** reading the last position, so plrStep() signals EOF by setting
** pData to NULL.
*/
const char *pData;
int nData;
DocListType iType;
int iColumn; /* the last column read */
int iPosition; /* the last position read */
int iStartOffset; /* the last start offset read */
int iEndOffset; /* the last end offset read */
} PLReader;
static int plrAtEnd(PLReader *pReader){
return pReader->pData==NULL;
}
static int plrColumn(PLReader *pReader){
assert( !plrAtEnd(pReader) );
return pReader->iColumn;
}
static int plrPosition(PLReader *pReader){
assert( !plrAtEnd(pReader) );
return pReader->iPosition;
}
static int plrStartOffset(PLReader *pReader){
assert( !plrAtEnd(pReader) );
return pReader->iStartOffset;
}
static int plrEndOffset(PLReader *pReader){
assert( !plrAtEnd(pReader) );
return pReader->iEndOffset;
}
static void plrStep(PLReader *pReader){
int i, n;
assert( !plrAtEnd(pReader) );
if( pReader->nData==0 ){
pReader->pData = NULL;
return;
}
n = getVarint32(pReader->pData, &i);
if( i==POS_COLUMN ){
n += getVarint32(pReader->pData+n, &pReader->iColumn);
pReader->iPosition = 0;
pReader->iStartOffset = 0;
n += getVarint32(pReader->pData+n, &i);
}
/* Should never see adjacent column changes. */
assert( i!=POS_COLUMN );
if( i==POS_END ){
pReader->nData = 0;
pReader->pData = NULL;
return;
}
pReader->iPosition += i-POS_BASE;
if( pReader->iType==DL_POSITIONS_OFFSETS ){
n += getVarint32(pReader->pData+n, &i);
pReader->iStartOffset += i;
n += getVarint32(pReader->pData+n, &i);
pReader->iEndOffset = pReader->iStartOffset+i;
}
assert( n<=pReader->nData );
pReader->pData += n;
pReader->nData -= n;
}
static void plrInit(PLReader *pReader, DocListType iType,
const char *pData, int nData){
pReader->pData = pData;
pReader->nData = nData;
pReader->iType = iType;
pReader->iColumn = 0;
pReader->iPosition = 0;
pReader->iStartOffset = 0;
pReader->iEndOffset = 0;
plrStep(pReader);
}
static void plrDestroy(PLReader *pReader){
SCRAMBLE(pReader);
}
/*******************************************************************/
/* PLWriter is used in constructing a document's position list. As a
** convenience, if iType is DL_DOCIDS, PLWriter becomes a no-op.
**
** plwInit - init for writing a document's poslist.
** plwReset - reset the writer for a new document.
** plwDestroy - clear a writer.
** plwNew - malloc storage and initialize it.
** plwDelete - clear and free storage.
** plwDlwAdd - append the docid and poslist to a doclist writer.
** plwAdd - append position and offset information.
*/
/* TODO(shess) PLWriter is used in two ways. fulltextUpdate() uses it
** in construction of a new doclist. docListTrim() and mergePosList()
** use it when trimming. In the former case, it wants to own the
** DataBuffer, in the latter it's possible it could encode into a
** pre-existing DataBuffer.
*/
typedef struct PLWriter {
DataBuffer b;
sqlite_int64 iDocid;
DocListType iType;
int iColumn; /* the last column written */
int iPos; /* the last position written */
int iOffset; /* the last start offset written */
} PLWriter;
static void plwDlwAdd(PLWriter *pWriter, DLWriter *dlWriter){
dlwAdd(dlWriter, pWriter->iDocid, pWriter->b.pData, pWriter->b.nData);
}
static void plwAdd(PLWriter *pWriter, int iColumn, int iPos,
int iStartOffset, int iEndOffset){
/* Worst-case space for POS_COLUMN, iColumn, iPosDelta,
** iStartOffsetDelta, and iEndOffsetDelta.
*/
char c[5*VARINT_MAX];
int n = 0;
if( pWriter->iType==DL_DOCIDS ) return;
if( iColumn!=pWriter->iColumn ){
n += putVarint(c+n, POS_COLUMN);
n += putVarint(c+n, iColumn);
pWriter->iColumn = iColumn;
pWriter->iPos = 0;
pWriter->iOffset = 0;
}
assert( iPos>=pWriter->iPos );
n += putVarint(c+n, POS_BASE+(iPos-pWriter->iPos));
pWriter->iPos = iPos;
if( pWriter->iType==DL_POSITIONS_OFFSETS ){
assert( iStartOffset>=pWriter->iOffset );
n += putVarint(c+n, iStartOffset-pWriter->iOffset);
pWriter->iOffset = iStartOffset;
assert( iEndOffset>=iStartOffset );
n += putVarint(c+n, iEndOffset-iStartOffset);
}
dataBufferAppend(&pWriter->b, c, n);
}
static void plwReset(PLWriter *pWriter,
sqlite_int64 iDocid, DocListType iType){
dataBufferReset(&pWriter->b);
pWriter->iDocid = iDocid;
pWriter->iType = iType;
pWriter->iColumn = 0;
pWriter->iPos = 0;
pWriter->iOffset = 0;
}
static void plwInit(PLWriter *pWriter, sqlite_int64 iDocid, DocListType iType){
dataBufferInit(&pWriter->b, 0);
plwReset(pWriter, iDocid, iType);
}
static PLWriter *plwNew(sqlite_int64 iDocid, DocListType iType){
PLWriter *pWriter = malloc(sizeof(PLWriter));
plwInit(pWriter, iDocid, iType);
return pWriter;
}
static void plwDestroy(PLWriter *pWriter){
dataBufferDestroy(&pWriter->b);
SCRAMBLE(pWriter);
}
static void plwDelete(PLWriter *pWriter){
plwDestroy(pWriter);
free(pWriter);
}
/* Copy the doclist data of iType in pData/nData into *out, trimming
** unnecessary data as we go. Only columns matching iColumn are
** copied, all columns copied if iColimn is -1. Elements with no
** matching columns are dropped. The output is an iOutType doclist.
*/
static void docListTrim(DocListType iType, const char *pData, int nData,
int iColumn, DocListType iOutType, DataBuffer *out){
DLReader dlReader;
DLWriter dlWriter;
PLWriter plWriter;
assert( iOutType<=iType );
dlrInit(&dlReader, iType, pData, nData);
dlwInit(&dlWriter, iOutType, out);
plwInit(&plWriter, 0, iOutType);
while( !dlrAtEnd(&dlReader) ){
PLReader plReader;
int match = 0;
plrInit(&plReader, dlReader.iType,
dlrPosData(&dlReader), dlrPosDataLen(&dlReader));
plwReset(&plWriter, dlrDocid(&dlReader), iOutType);
while( !plrAtEnd(&plReader) ){
if( iColumn==-1 || plrColumn(&plReader)==iColumn ){
match = 1;
plwAdd(&plWriter, plrColumn(&plReader), plrPosition(&plReader),
plrStartOffset(&plReader), plrEndOffset(&plReader));
}
plrStep(&plReader);
}
if( match ) plwDlwAdd(&plWriter, &dlWriter);
plrDestroy(&plReader);
dlrStep(&dlReader);
}
plwDestroy(&plWriter);
dlwDestroy(&dlWriter);
dlrDestroy(&dlReader);
}
/* Used by docListMerge() to keep doclists in the ascending order by
** docid, then ascending order by age (so the newest comes first).
*/
typedef struct OrderedDLReader {
DLReader *pReader;
/* TODO(shess) If we assume that docListMerge pReaders is ordered by
** age (which we do), then we could use pReader comparisons to break
** ties.
*/
int idx;
} OrderedDLReader;
/* Order eof to end, then by docid asc, idx desc. */
static int orderedDLReaderCmp(OrderedDLReader *r1, OrderedDLReader *r2){
if( dlrAtEnd(r1->pReader) ){
if( dlrAtEnd(r2->pReader) ) return 0; /* Both atEnd(). */
return 1; /* Only r1 atEnd(). */
}
if( dlrAtEnd(r2->pReader) ) return -1; /* Only r2 atEnd(). */
if( dlrDocid(r1->pReader)<dlrDocid(r2->pReader) ) return -1;
if( dlrDocid(r1->pReader)>dlrDocid(r2->pReader) ) return 1;
/* Descending on idx. */
return r2->idx-r1->idx;
}
/* Bubble p[0] to appropriate place in p[1..n-1]. Assumes that
** p[1..n-1] is already sorted.
*/
/* TODO(shess) Is this frequent enough to warrant a binary search?
** Before implementing that, instrument the code to check. In most
** current usage, I expect that p[0] will be less than p[1] a very
** high proportion of the time.
*/
static void orderedDLReaderReorder(OrderedDLReader *p, int n){
while( n>1 && orderedDLReaderCmp(p, p+1)>0 ){
OrderedDLReader tmp = p[0];
p[0] = p[1];
p[1] = tmp;
n--;
p++;
}
}
/* Given an array of doclist readers, merge their doclist elements
** into out in sorted order (by docid), dropping elements from older
** readers when there is a duplicate docid. pReaders is assumed to be
** ordered by age, oldest first.
*/
/* TODO(shess) nReaders must be <= MERGE_COUNT. This should probably
** be fixed.
*/
static void docListMerge(DataBuffer *out,
DLReader *pReaders, int nReaders){
OrderedDLReader readers[MERGE_COUNT];
DLWriter writer;
int i, n;
const char *pStart = 0;
int nStart = 0;
sqlite_int64 iFirstDocid = 0, iLastDocid = 0;
assert( nReaders>0 );
if( nReaders==1 ){
dataBufferAppend(out, dlrDocData(pReaders), dlrAllDataBytes(pReaders));
return;
}
assert( nReaders<=MERGE_COUNT );
n = 0;
for(i=0; i<nReaders; i++){
assert( pReaders[i].iType==pReaders[0].iType );
readers[i].pReader = pReaders+i;
readers[i].idx = i;
n += dlrAllDataBytes(&pReaders[i]);
}
/* Conservatively size output to sum of inputs. Output should end
** up strictly smaller than input.
*/
dataBufferExpand(out, n);
/* Get the readers into sorted order. */
while( i-->0 ){
orderedDLReaderReorder(readers+i, nReaders-i);
}
dlwInit(&writer, pReaders[0].iType, out);
while( !dlrAtEnd(readers[0].pReader) ){
sqlite_int64 iDocid = dlrDocid(readers[0].pReader);
/* If this is a continuation of the current buffer to copy, extend
** that buffer. memcpy() seems to be more efficient if it has a
** lots of data to copy.
*/
if( dlrDocData(readers[0].pReader)==pStart+nStart ){
nStart += dlrDocDataBytes(readers[0].pReader);
}else{
if( pStart!=0 ){
dlwAppend(&writer, pStart, nStart, iFirstDocid, iLastDocid);
}
pStart = dlrDocData(readers[0].pReader);
nStart = dlrDocDataBytes(readers[0].pReader);
iFirstDocid = iDocid;
}
iLastDocid = iDocid;
dlrStep(readers[0].pReader);
/* Drop all of the older elements with the same docid. */
for(i=1; i<nReaders &&
!dlrAtEnd(readers[i].pReader) &&
dlrDocid(readers[i].pReader)==iDocid; i++){
dlrStep(readers[i].pReader);
}
/* Get the readers back into order. */
while( i-->0 ){
orderedDLReaderReorder(readers+i, nReaders-i);
}
}
/* Copy over any remaining elements. */
if( nStart>0 ) dlwAppend(&writer, pStart, nStart, iFirstDocid, iLastDocid);
dlwDestroy(&writer);
}
/* pLeft and pRight are DLReaders positioned to the same docid.
**
** 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.
*/
static void mergePosList(DLReader *pLeft, DLReader *pRight, DLWriter *pOut){
PLReader left, right;
PLWriter writer;
int match = 0;
assert( dlrDocid(pLeft)==dlrDocid(pRight) );
assert( pOut->iType!=DL_POSITIONS_OFFSETS );
plrInit(&left, pLeft->iType, dlrPosData(pLeft), dlrPosDataLen(pLeft));
plrInit(&right, pRight->iType, dlrPosData(pRight), dlrPosDataLen(pRight));
plwInit(&writer, dlrDocid(pLeft), pOut->iType);
while( !plrAtEnd(&left) && !plrAtEnd(&right) ){
if( plrColumn(&left)<plrColumn(&right) ){
plrStep(&left);
}else if( plrColumn(&left)>plrColumn(&right) ){
plrStep(&right);
}else if( plrPosition(&left)+1<plrPosition(&right) ){
plrStep(&left);
}else if( plrPosition(&left)+1>plrPosition(&right) ){
plrStep(&right);
}else{
match = 1;
plwAdd(&writer, plrColumn(&right), plrPosition(&right), 0, 0);
plrStep(&left);
plrStep(&right);
}
}
/* TODO(shess) We could remember the output position, encode the
** docid, then encode the poslist directly into the output. If no
** match, we back out to the stored output position. This would
** also reduce the malloc count.
*/
if( match ) plwDlwAdd(&writer, pOut);
plrDestroy(&left);
plrDestroy(&right);
plwDestroy(&writer);
}
/* We have two doclists with positions: 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.
**
** iType controls the type of data written to pOut. If iType is
** DL_POSITIONS, the positions are those from pRight.
*/
static void docListPhraseMerge(
const char *pLeft, int nLeft,
const char *pRight, int nRight,
DocListType iType,
DataBuffer *pOut /* Write the combined doclist here */
){
DLReader left, right;
DLWriter writer;
if( nLeft==0 || nRight==0 ) return;
assert( iType!=DL_POSITIONS_OFFSETS );
dlrInit(&left, DL_POSITIONS, pLeft, nLeft);
dlrInit(&right, DL_POSITIONS, pRight, nRight);
dlwInit(&writer, iType, pOut);
while( !dlrAtEnd(&left) && !dlrAtEnd(&right) ){
if( dlrDocid(&left)<dlrDocid(&right) ){
dlrStep(&left);
}else if( dlrDocid(&right)<dlrDocid(&left) ){
dlrStep(&right);
}else{
mergePosList(&left, &right, &writer);
dlrStep(&left);
dlrStep(&right);
}
}
dlrDestroy(&left);
dlrDestroy(&right);
dlwDestroy(&writer);
}
/* We have two DL_DOCIDS doclists: pLeft and pRight.
** Write the intersection of these two doclists into pOut as a
** DL_DOCIDS doclist.
*/
static void docListAndMerge(
const char *pLeft, int nLeft,
const char *pRight, int nRight,
DataBuffer *pOut /* Write the combined doclist here */
){
DLReader left, right;
DLWriter writer;
if( nLeft==0 || nRight==0 ) return;
dlrInit(&left, DL_DOCIDS, pLeft, nLeft);
dlrInit(&right, DL_DOCIDS, pRight, nRight);
dlwInit(&writer, DL_DOCIDS, pOut);
while( !dlrAtEnd(&left) && !dlrAtEnd(&right) ){
if( dlrDocid(&left)<dlrDocid(&right) ){
dlrStep(&left);
}else if( dlrDocid(&right)<dlrDocid(&left) ){
dlrStep(&right);
}else{
dlwAdd(&writer, dlrDocid(&left), 0, 0);
dlrStep(&left);
dlrStep(&right);
}
}
dlrDestroy(&left);
dlrDestroy(&right);
dlwDestroy(&writer);
}
/* We have two DL_DOCIDS doclists: pLeft and pRight.
** Write the union of these two doclists into pOut as a
** DL_DOCIDS doclist.
*/
static void docListOrMerge(
const char *pLeft, int nLeft,
const char *pRight, int nRight,
DataBuffer *pOut /* Write the combined doclist here */
){
DLReader left, right;
DLWriter writer;
if( nLeft==0 ){
dataBufferAppend(pOut, pRight, nRight);
return;
}
if( nRight==0 ){
dataBufferAppend(pOut, pLeft, nLeft);
return;
}
dlrInit(&left, DL_DOCIDS, pLeft, nLeft);
dlrInit(&right, DL_DOCIDS, pRight, nRight);
dlwInit(&writer, DL_DOCIDS, pOut);
while( !dlrAtEnd(&left) || !dlrAtEnd(&right) ){
if( dlrAtEnd(&right) || dlrDocid(&left)<dlrDocid(&right) ){
dlwAdd(&writer, dlrDocid(&left), 0, 0);
dlrStep(&left);
}else if( dlrAtEnd(&left) || dlrDocid(&right)<dlrDocid(&left) ){
dlwAdd(&writer, dlrDocid(&right), 0, 0);
dlrStep(&right);
}else{
dlwAdd(&writer, dlrDocid(&left), 0, 0);
dlrStep(&left);
dlrStep(&right);
}
}
dlrDestroy(&left);
dlrDestroy(&right);
dlwDestroy(&writer);
}
/* We have two DL_DOCIDS doclists: pLeft and pRight.
** Write into pOut as DL_DOCIDS doclist containing all documents that
** occur in pLeft but not in pRight.
*/
static void docListExceptMerge(
const char *pLeft, int nLeft,
const char *pRight, int nRight,
DataBuffer *pOut /* Write the combined doclist here */
){
DLReader left, right;
DLWriter writer;
if( nLeft==0 ) return;
if( nRight==0 ){
dataBufferAppend(pOut, pLeft, nLeft);
return;
}
dlrInit(&left, DL_DOCIDS, pLeft, nLeft);
dlrInit(&right, DL_DOCIDS, pRight, nRight);
dlwInit(&writer, DL_DOCIDS, pOut);
while( !dlrAtEnd(&left) ){
while( !dlrAtEnd(&right) && dlrDocid(&right)<dlrDocid(&left) ){
dlrStep(&right);
}
if( dlrAtEnd(&right) || dlrDocid(&left)<dlrDocid(&right) ){
dlwAdd(&writer, dlrDocid(&left), 0, 0);
}
dlrStep(&left);
}
dlrDestroy(&left);
dlrDestroy(&right);
dlwDestroy(&writer);
}
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
* zDb.zName. This may be more convenient than sqlite_mprintf()
* when one string is used repeatedly in a format string.
* The caller must free() the returned string. */
static char *string_format(const char *zFormat,
const char *zDb, const char *zName){
const char *p;
size_t len = 0;
size_t nDb = strlen(zDb);
size_t nName = strlen(zName);
size_t nFullTableName = nDb+1+nName;
char *result;
char *r;
/* first compute length needed */
for(p = zFormat ; *p ; ++p){
len += (*p=='%' ? nFullTableName : 1);
}
len += 1; /* for null terminator */
r = result = malloc(len);
for(p = zFormat; *p; ++p){
if( *p=='%' ){
memcpy(r, zDb, nDb);
r += nDb;
*r++ = '.';
memcpy(r, zName, nName);
r += nName;
} else {
*r++ = *p;
}
}
*r++ = '\0';
assert( r == result + len );
return result;
}
static int sql_exec(sqlite3 *db, const char *zDb, const char *zName,
const char *zFormat){
char *zCommand = string_format(zFormat, zDb, zName);
int rc;
TRACE(("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 *zDb, const char *zName,
sqlite3_stmt **ppStmt, const char *zFormat){
char *zCommand = string_format(zFormat, zDb, 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;
typedef enum fulltext_statement {
CONTENT_INSERT_STMT,
CONTENT_SELECT_STMT,
CONTENT_UPDATE_STMT,
CONTENT_DELETE_STMT,
BLOCK_INSERT_STMT,
BLOCK_SELECT_STMT,
BLOCK_DELETE_STMT,
SEGDIR_MAX_INDEX_STMT,
SEGDIR_SET_STMT,
SEGDIR_SELECT_STMT,
SEGDIR_SPAN_STMT,
SEGDIR_DELETE_STMT,
SEGDIR_SELECT_ALL_STMT,
MAX_STMT /* Always at end! */
} fulltext_statement;
/* These must exactly match the enum above. */
/* TODO(shess): Is there some risk that a statement 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 = ?",
/* BLOCK_INSERT */ "insert into %_segments values (?)",
/* BLOCK_SELECT */ "select block from %_segments where rowid = ?",
/* BLOCK_DELETE */ "delete from %_segments where rowid between ? and ?",
/* SEGDIR_MAX_INDEX */ "select max(idx) from %_segdir where level = ?",
/* SEGDIR_SET */ "insert into %_segdir values (?, ?, ?, ?, ?, ?)",
/* SEGDIR_SELECT */
"select start_block, leaves_end_block, root from %_segdir "
" where level = ? order by idx",
/* SEGDIR_SPAN */
"select min(start_block), max(end_block) from %_segdir "
" where level = ? and start_block <> 0",
/* SEGDIR_DELETE */ "delete from %_segdir where level = ?",
/* SEGDIR_SELECT_ALL */ "select root from %_segdir order by level desc, idx",
};
/*
** A connection to a fulltext index is an instance of the following
** structure. The xCreate and xConnect methods create an instance
** of this structure and xDestroy and xDisconnect free that instance.
** All other methods receive a pointer to the structure as one of their
** arguments.
*/
struct fulltext_vtab {
sqlite3_vtab base; /* Base class used by SQLite core */
sqlite3 *db; /* The database connection */
const char *zDb; /* logical database name */
const char *zName; /* virtual table name */
int nColumn; /* number of columns in virtual table */
char **azColumn; /* column names. malloced */
char **azContentColumn; /* column names in content table; malloced */
sqlite3_tokenizer *pTokenizer; /* tokenizer for inserts and queries */
/* Precompiled statements which we keep as long as the table is
** open.
*/
sqlite3_stmt *pFulltextStatements[MAX_STMT];
/* Precompiled statements used for segment merges. We run a
** separate select across the leaf level of each tree being merged.
*/
sqlite3_stmt *pLeafSelectStmts[MERGE_COUNT];
/* The statement used to prepare pLeafSelectStmts. */
#define LEAF_SELECT \
"select block from %_segments where rowid between ? and ? order by rowid"
};
/*
** 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 */
DataBuffer result; /* Doclist results from fulltextQuery */
DLReader reader; /* Result reader if result not empty */
} fulltext_cursor;
static struct fulltext_vtab *cursor_vtab(fulltext_cursor *c){
return (fulltext_vtab *) c->base.pVtab;
}
static const sqlite3_module fulltextModule; /* forward declaration */
/* 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 stringBufferData(&sb);
}
/* 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 stringBufferData(&sb);
}
/* Puts a freshly-prepared statement determined by iStmt in *ppStmt.
** If the indicated statement has never been prepared, it is prepared
** and cached, otherwise the cached version is reset.
*/
static int sql_get_statement(fulltext_vtab *v, fulltext_statement iStmt,
sqlite3_stmt **ppStmt){
assert( iStmt<MAX_STMT );
if( v->pFulltextStatements[iStmt]==NULL ){
const char *zStmt;
int rc;
switch( iStmt ){
case CONTENT_INSERT_STMT:
zStmt = contentInsertStatement(v); break;
case CONTENT_UPDATE_STMT:
zStmt = contentUpdateStatement(v); break;
default:
zStmt = fulltext_zStatement[iStmt];
}
rc = sql_prepare(v->db, v->zDb, v->zName, &v->pFulltextStatements[iStmt],
zStmt);
if( zStmt != fulltext_zStatement[iStmt]) free((void *) zStmt);
if( rc!=SQLITE_OK ) return rc;
} else {
int rc = sqlite3_reset(v->pFulltextStatements[iStmt]);
if( rc!=SQLITE_OK ) return rc;
}
*ppStmt = v->pFulltextStatements[iStmt];
return SQLITE_OK;
}
/* Step the indicated statement, handling errors SQLITE_BUSY (by
** retrying) and SQLITE_SCHEMA (by re-preparing and transferring
** bindings to the new statement).
** TODO(adam): We should extend this function so that it can work with
** statements declared locally, not only globally cached statements.
*/
static int sql_step_statement(fulltext_vtab *v, fulltext_statement iStmt,
sqlite3_stmt **ppStmt){
int rc;
sqlite3_stmt *s = *ppStmt;
assert( iStmt<MAX_STMT );
assert( s==v->pFulltextStatements[iStmt] );
while( (rc=sqlite3_step(s))!=SQLITE_DONE && rc!=SQLITE_ROW ){
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;
}
/* Like sql_get_statement(), but for special replicated LEAF_SELECT
** statements.
*/
/* TODO(shess) Write version for generic statements and then share
** that between the cached-statement functions.
*/
static int sql_get_leaf_statement(fulltext_vtab *v, int idx,
sqlite3_stmt **ppStmt){
assert( idx>=0 && idx<MERGE_COUNT );
if( v->pLeafSelectStmts[idx]==NULL ){
int rc = sql_prepare(v->db, v->zDb, v->zName, &v->pLeafSelectStmts[idx],
LEAF_SELECT);
if( rc!=SQLITE_OK ) return rc;
}else{
int rc = sqlite3_reset(v->pLeafSelectStmts[idx]);
if( rc!=SQLITE_OK ) return rc;
}
*ppStmt = v->pLeafSelectStmts[idx];
return SQLITE_OK;
}
/* Like sql_step_statement(), but for special replicated LEAF_SELECT
** statements.
*/
/* TODO(shess) Write version for generic statements and then share
** that between the cached-statement functions.
*/
static int sql_step_leaf_statement(fulltext_vtab *v, int idx,
sqlite3_stmt **ppStmt){
int rc;
sqlite3_stmt *s = *ppStmt;
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->pLeafSelectStmts[idx] = NULL; /* Still in s */
rc = sql_get_leaf_statement(v, idx, &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;
}
/* insert into %_content (rowid, ...) values ([rowid], [pValues]) */
static int content_insert(fulltext_vtab *v, sqlite3_value *rowid,
sqlite3_value **pValues){
sqlite3_stmt *s;
int i;
int rc = sql_get_statement(v, CONTENT_INSERT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_value(s, 1, rowid);
if( rc!=SQLITE_OK ) return rc;
for(i=0; i<v->nColumn; ++i){
rc = sqlite3_bind_value(s, 2+i, pValues[i]);
if( rc!=SQLITE_OK ) return rc;
}
return sql_single_step_statement(v, CONTENT_INSERT_STMT, &s);
}
/* update %_content set col0 = pValues[0], col1 = pValues[1], ...
* where rowid = [iRowid] */
static int content_update(fulltext_vtab *v, sqlite3_value **pValues,
sqlite_int64 iRowid){
sqlite3_stmt *s;
int i;
int rc = sql_get_statement(v, CONTENT_UPDATE_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
for(i=0; i<v->nColumn; ++i){
rc = sqlite3_bind_value(s, 1+i, pValues[i]);
if( rc!=SQLITE_OK ) return rc;
}
rc = sqlite3_bind_int64(s, 1+v->nColumn, iRowid);
if( rc!=SQLITE_OK ) return rc;
return sql_single_step_statement(v, CONTENT_UPDATE_STMT, &s);
}
static void freeStringArray(int nString, const char **pString){
int i;
for (i=0 ; i < nString ; ++i) {
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);
}
/* insert into %_segments values ([pData])
** returns assigned rowid in *piBlockid
*/
static int block_insert(fulltext_vtab *v, const char *pData, int nData,
sqlite_int64 *piBlockid){
sqlite3_stmt *s;
int rc = sql_get_statement(v, BLOCK_INSERT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_blob(s, 1, pData, nData, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, BLOCK_INSERT_STMT, &s);
if( rc==SQLITE_ROW ) return SQLITE_ERROR;
if( rc!=SQLITE_DONE ) return rc;
*piBlockid = sqlite3_last_insert_rowid(v->db);
return SQLITE_OK;
}
/* delete from %_segments
** where rowid between [iStartBlockid] and [iEndBlockid]
**
** Deletes the range of blocks, inclusive, used to delete the blocks
** which form a segment.
*/
static int block_delete(fulltext_vtab *v,
sqlite_int64 iStartBlockid, sqlite_int64 iEndBlockid){
sqlite3_stmt *s;
int rc = sql_get_statement(v, BLOCK_DELETE_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 1, iStartBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 2, iEndBlockid);
if( rc!=SQLITE_OK ) return rc;
return sql_single_step_statement(v, BLOCK_DELETE_STMT, &s);
}
/* Returns SQLITE_ROW with *pidx set to the maximum segment idx found
** at iLevel. Returns SQLITE_DONE if there are no segments at
** iLevel. Otherwise returns an error.
*/
static int segdir_max_index(fulltext_vtab *v, int iLevel, int *pidx){
sqlite3_stmt *s;
int rc = sql_get_statement(v, SEGDIR_MAX_INDEX_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 1, iLevel);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, SEGDIR_MAX_INDEX_STMT, &s);
/* Should always get at least one row due to how max() works. */
if( rc==SQLITE_DONE ) return SQLITE_DONE;
if( rc!=SQLITE_ROW ) return rc;
/* NULL means that there were no inputs to max(). */
if( SQLITE_NULL==sqlite3_column_type(s, 0) ){
rc = sqlite3_step(s);
if( rc==SQLITE_ROW ) return SQLITE_ERROR;
return rc;
}
*pidx = sqlite3_column_int(s, 0);
/* We expect only one row. We must execute another sqlite3_step()
* to complete the iteration; otherwise the table will remain locked. */
rc = sqlite3_step(s);
if( rc==SQLITE_ROW ) return SQLITE_ERROR;
if( rc!=SQLITE_DONE ) return rc;
return SQLITE_ROW;
}
/* insert into %_segdir values (
** [iLevel], [idx],
** [iStartBlockid], [iLeavesEndBlockid], [iEndBlockid],
** [pRootData]
** )
*/
static int segdir_set(fulltext_vtab *v, int iLevel, int idx,
sqlite_int64 iStartBlockid,
sqlite_int64 iLeavesEndBlockid,
sqlite_int64 iEndBlockid,
const char *pRootData, int nRootData){
sqlite3_stmt *s;
int rc = sql_get_statement(v, SEGDIR_SET_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 1, iLevel);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 2, idx);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 3, iStartBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 4, iLeavesEndBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 5, iEndBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_blob(s, 6, pRootData, nRootData, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
return sql_single_step_statement(v, SEGDIR_SET_STMT, &s);
}
/* Queries %_segdir for the block span of the segments in level
** iLevel. Returns SQLITE_DONE if there are no blocks for iLevel,
** SQLITE_ROW if there are blocks, else an error.
*/
static int segdir_span(fulltext_vtab *v, int iLevel,
sqlite_int64 *piStartBlockid,
sqlite_int64 *piEndBlockid){
sqlite3_stmt *s;
int rc = sql_get_statement(v, SEGDIR_SPAN_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 1, iLevel);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, SEGDIR_SPAN_STMT, &s);
if( rc==SQLITE_DONE ) return SQLITE_DONE; /* Should never happen */
if( rc!=SQLITE_ROW ) return rc;
/* This happens if all segments at this level are entirely inline. */
if( SQLITE_NULL==sqlite3_column_type(s, 0) ){
/* We expect only one row. We must execute another sqlite3_step()
* to complete the iteration; otherwise the table will remain locked. */
int rc2 = sqlite3_step(s);
if( rc2==SQLITE_ROW ) return SQLITE_ERROR;
return rc2;
}
*piStartBlockid = sqlite3_column_int64(s, 0);
*piEndBlockid = sqlite3_column_int64(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);
if( rc==SQLITE_ROW ) return SQLITE_ERROR;
if( rc!=SQLITE_DONE ) return rc;
return SQLITE_ROW;
}
/* Delete the segment blocks and segment directory records for all
** segments at iLevel.
*/
static int segdir_delete(fulltext_vtab *v, int iLevel){
sqlite3_stmt *s;
sqlite_int64 iStartBlockid, iEndBlockid;
int rc = segdir_span(v, iLevel, &iStartBlockid, &iEndBlockid);
if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ) return rc;
if( rc==SQLITE_ROW ){
rc = block_delete(v, iStartBlockid, iEndBlockid);
if( rc!=SQLITE_OK ) return rc;
}
/* Delete the segment directory itself. */
rc = sql_get_statement(v, SEGDIR_DELETE_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 1, iLevel);
if( rc!=SQLITE_OK ) return rc;
return sql_single_step_statement(v, SEGDIR_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;
}
}
for( i=0; i<MERGE_COUNT; i++ ){
if( v->pLeafSelectStmts[i]!=NULL ){
sqlite3_finalize(v->pLeafSelectStmts[i]);
v->pLeafSelectStmts[i] = 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
*/
static void dequoteString(char *z){
int quote;
int i, j;
if( z==0 ) return;
quote = z[0];
switch( quote ){
case '\'': break;
case '"': break;
case '`': break; /* For MySQL compatibility */
case '[': quote = ']'; break; /* For MS SqlServer compatibility */
default: return;
}
for(i=1, j=0; z[i]; i++){
if( z[i]==quote ){
if( z[i+1]==quote ){
z[j++] = quote;
i++;
}else{
z[j++] = 0;
break;
}
}else{
z[j++] = z[i];
}
}
}
/*
** The input azIn is a NULL-terminated list of tokens. Remove the first
** token and all punctuation tokens. Remove the quotes from
** around string literal tokens.
**
** Example:
**
** input: tokenize chinese ( 'simplifed' , 'mixed' )
** output: chinese simplifed mixed
**
** Another example:
**
** input: delimiters ( '[' , ']' , '...' )
** output: [ ] ...
*/
static void tokenListToIdList(char **azIn){
int i, j;
if( azIn ){
for(i=0, j=-1; azIn[i]; i++){
if( isalnum(azIn[i][0]) || azIn[i][1] ){
dequoteString(azIn[i]);
if( j>=0 ){
azIn[j] = azIn[i];
}
j++;
}
}
azIn[j] = 0;
}
}
/*
** Find the first alphanumeric token in the string zIn. Null-terminate
** this token. Remove any quotation marks. And return a pointer to
** the result.
*/
static char *firstToken(char *zIn, char **pzTail){
int n, ttype;
while(1){
n = getToken(zIn, &ttype);
if( ttype==TOKEN_SPACE ){
zIn += n;
}else if( ttype==TOKEN_EOF ){
*pzTail = zIn;
return 0;
}else{
zIn[n] = 0;
*pzTail = &zIn[1];
dequoteString(zIn);
return zIn;
}
}
/*NOTREACHED*/
}
/* Return true if...
**
** * s begins with the string t, ignoring case
** * s is longer than t
** * The first character of s beyond t is not a alphanumeric
**
** Ignore leading space in *s.
**
** To put it another way, return true if the first token of
** s[] is t[].
*/
static int startsWith(const char *s, const char *t){
while( 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 *zDb; /* Logical database name */
const char *zName; /* Name of the full-text index */
int nColumn; /* Number of columns to be indexed */
char **azColumn; /* Original names of columns to be indexed */
char **azContentColumn; /* Column names for %_content */
char **azTokenizer; /* Name of tokenizer and its arguments */
} TableSpec;
/*
** Reclaim all of the memory used by a TableSpec
*/
static void clearTableSpec(TableSpec *p) {
free(p->azColumn);
free(p->azContentColumn);
free(p->azTokenizer);
}
/* Parse a CREATE VIRTUAL TABLE statement, which looks like this:
*
* CREATE VIRTUAL TABLE email
* USING fts2(subject, body, tokenize mytokenizer(myarg))
*
* We return parsed information in a TableSpec structure.
*
*/
static int parseSpec(TableSpec *pSpec, int argc, const char *const*argv,
char**pzErr){
int i, n;
char *z, *zDummy;
char **azArg;
const char *zTokenizer = 0; /* argv[] entry describing the tokenizer */
assert( argc>=3 );
/* Current interface:
** argv[0] - module name
** argv[1] - database name
** argv[2] - table name
** argv[3..] - columns, optionally followed by tokenizer specification
** and snippet delimiters specification.
*/
/* Make a copy of the complete argv[][] array in a single allocation.
** The argv[][] array is read-only and transient. We can write to the
** copy in order to modify things and the copy is persistent.
*/
CLEAR(pSpec);
for(i=n=0; i<argc; i++){
n += strlen(argv[i]) + 1;
}
azArg = malloc( sizeof(char*)*argc + n );
if( azArg==0 ){
return SQLITE_NOMEM;
}
z = (char*)&azArg[argc];
for(i=0; i<argc; i++){
azArg[i] = z;
strcpy(z, argv[i]);
z += strlen(z)+1;
}
/* Identify the column names and the tokenizer and delimiter arguments
** in the argv[][] array.
*/
pSpec->zDb = azArg[1];
pSpec->zName = azArg[2];
pSpec->nColumn = 0;
pSpec->azColumn = azArg;
zTokenizer = "tokenize simple";
for(i=3; i<argc; ++i){
if( startsWith(azArg[i],"tokenize") ){
zTokenizer = azArg[i];
}else{
z = azArg[pSpec->nColumn] = firstToken(azArg[i], &zDummy);
pSpec->nColumn++;
}
}
if( pSpec->nColumn==0 ){
azArg[0] = "content";
pSpec->nColumn = 1;
}
/*
** Construct the list of content column names.
**
** Each content column name will be of the form cNNAAAA
** where NN is the column number and AAAA is the sanitized
** column name. "sanitized" means that special characters are
** converted to "_". The cNN prefix guarantees that all column
** names are unique.
**
** The AAAA suffix is not strictly necessary. It is included
** for the convenience of people who might examine the generated
** %_content table and wonder what the columns are used for.
*/
pSpec->azContentColumn = malloc( pSpec->nColumn * sizeof(char *) );
if( pSpec->azContentColumn==0 ){
clearTableSpec(pSpec);
return SQLITE_NOMEM;
}
for(i=0; i<pSpec->nColumn; i++){
char *p;
pSpec->azContentColumn[i] = sqlite3_mprintf("c%d%s", i, azArg[i]);
for (p = pSpec->azContentColumn[i]; *p ; ++p) {
if( !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;
CLEAR(v);
/* sqlite will initialize v->base */
v->db = db;
v->zDb = spec->zDb; /* Freed when azColumn is freed */
v->zName = spec->zName; /* Freed when azColumn is freed */
v->nColumn = spec->nColumn;
v->azContentColumn = spec->azContentColumn;
spec->azContentColumn = 0;
v->azColumn = spec->azColumn;
spec->azColumn = 0;
if( spec->azTokenizer==0 ){
return SQLITE_NOMEM;
}
/* TODO(shess) For now, add new tokenizers as else if clauses. */
if( spec->azTokenizer[0]==0 || startsWith(spec->azTokenizer[0], "simple") ){
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.
*/
/* TODO(shess) This comment needs elaboration to match the updated
** code. Work it into the top-of-file comment at that time.
*/
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.zDb, spec.zName, stringBufferData(&schema));
stringBufferDestroy(&schema);
if( rc!=SQLITE_OK ) goto out;
rc = sql_exec(db, spec.zDb, spec.zName,
"create table %_segments(block blob);");
if( rc!=SQLITE_OK ) goto out;
rc = sql_exec(db, spec.zDb, spec.zName,
"create table %_segdir("
" level integer,"
" idx integer,"
" start_block integer,"
" leaves_end_block integer,"
" end_block integer,"
" root blob,"
" primary key(level, idx)"
");");
if( rc!=SQLITE_OK ) goto out;
rc = constructVtab(db, &spec, ppVTab, pzErr);
out:
clearTableSpec(&spec);
return rc;
}
/* Decide how to handle an SQL query. */
static int fulltextBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
int i;
TRACE(("FTS2 BestIndex\n"));
for(i=0; i<pInfo->nConstraint; ++i){
const struct sqlite3_index_constraint *pConstraint;
pConstraint = &pInfo->aConstraint[i];
if( pConstraint->usable ) {
if( pConstraint->iColumn==-1 &&
pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ ){
pInfo->idxNum = QUERY_ROWID; /* lookup by rowid */
TRACE(("FTS2 QUERY_ROWID\n"));
} else if( pConstraint->iColumn>=0 &&
pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
/* full-text search */
pInfo->idxNum = QUERY_FULLTEXT + pConstraint->iColumn;
TRACE(("FTS2 QUERY_FULLTEXT %d\n", pConstraint->iColumn));
} else continue;
pInfo->aConstraintUsage[i].argvIndex = 1;
pInfo->aConstraintUsage[i].omit = 1;
/* An arbitrary value for now.
* TODO: Perhaps rowid matches should be considered cheaper than
* full-text searches. */
pInfo->estimatedCost = 1.0;
return SQLITE_OK;
}
}
pInfo->idxNum = QUERY_GENERIC;
return SQLITE_OK;
}
static int fulltextDisconnect(sqlite3_vtab *pVTab){
TRACE(("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->zDb, v->zName,
"drop table if exists %_content;"
"drop table if exists %_segments;"
"drop table if exists %_segdir;"
);
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);
CLEAR(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);
CLEAR(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 = stringBufferData(&sb);
p->nOffset = stringBufferLength(&sb);
}
/*
** 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;
}
/*
** 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 = stringBufferData(&sb);
pCursor->snippet.nSnippet = stringBufferLength(&sb);
}
/*
** 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.nData!=0 ) dlrDestroy(&c->reader);
dataBufferDestroy(&c->result);
free(c);
return SQLITE_OK;
}
static int fulltextNext(sqlite3_vtab_cursor *pCursor){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
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;
if( c->result.nData==0 || dlrAtEnd(&c->reader) ){
c->eof = 1;
return SQLITE_OK;
}
rc = sqlite3_bind_int64(c->pStmt, 1, dlrDocid(&c->reader));
dlrStep(&c->reader);
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;
}
}
/* TODO(shess) If we pushed LeafReader to the top of the file, or to
** another file, term_select() could be pushed above
** docListOfTerm().
*/
static int termSelect(fulltext_vtab *v, int iColumn,
const char *pTerm, int nTerm,
DocListType iType, DataBuffer *out);
/* 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 resulting DL_DOCIDS doclist is stored in pResult, which is
** overwritten.
*/
static int docListOfTerm(
fulltext_vtab *v, /* The full text index */
int iColumn, /* column to restrict to. No restriction if >=nColumn */
QueryTerm *pQTerm, /* Term we are looking for, or 1st term of a phrase */
DataBuffer *pResult /* Write the result here */
){
DataBuffer left, right, new;
int i, rc;
/* No phrase search if no position info. */
assert( pQTerm->nPhrase==0 || DL_DEFAULT!=DL_DOCIDS );
dataBufferInit(&left, 0);
rc = termSelect(v, iColumn, pQTerm->pTerm, pQTerm->nTerm,
0<pQTerm->nPhrase ? DL_POSITIONS : DL_DOCIDS, &left);
if( rc ) return rc;
for(i=1; i<=pQTerm->nPhrase && left.nData>0; i++){
dataBufferInit(&right, 0);
rc = termSelect(v, iColumn, pQTerm[i].pTerm, pQTerm[i].nTerm,
DL_POSITIONS, &right);
if( rc ){
dataBufferDestroy(&left);
return rc;
}
dataBufferInit(&new, 0);
docListPhraseMerge(left.pData, left.nData, right.pData, right.nData,
i<pQTerm->nPhrase ? DL_POSITIONS : DL_DOCIDS, &new);
dataBufferDestroy(&left);
dataBufferDestroy(&right);
left = new;
}
*pResult = left;
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];
CLEAR(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[] */
DataBuffer *pResult, /* Write the result doclist here */
Query *pQuery /* Put parsed query string here */
){
int i, iNext, rc;
DataBuffer left, right, or, new;
int nNot = 0;
QueryTerm *aTerm;
/* TODO(shess) I think that the queryClear() calls below are not
** necessary, because fulltextClose() already clears the query.
*/
rc = parseQuery(v, zInput, nInput, iColumn, pQuery);
if( rc!=SQLITE_OK ) return rc;
/* Empty or NULL queries return no results. */
if( pQuery->nTerms==0 ){
dataBufferInit(pResult, 0);
return SQLITE_OK;
}
/* Merge AND terms. */
/* TODO(shess) I think we can early-exit if( i>nNot && left.nData==0 ). */
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], &right);
if( rc ){
if( i!=nNot ) dataBufferDestroy(&left);
queryClear(pQuery);
return rc;
}
while( iNext<pQuery->nTerms && aTerm[iNext].isOr ){
rc = docListOfTerm(v, aTerm[iNext].iColumn, &aTerm[iNext], &or);
iNext += aTerm[iNext].nPhrase + 1;
if( rc ){
if( i!=nNot ) dataBufferDestroy(&left);
dataBufferDestroy(&right);
queryClear(pQuery);
return rc;
}
dataBufferInit(&new, 0);
docListOrMerge(right.pData, right.nData, or.pData, or.nData, &new);
dataBufferDestroy(&right);
dataBufferDestroy(&or);
right = new;
}
if( i==nNot ){ /* first term processed. */
left = right;
}else{
dataBufferInit(&new, 0);
docListAndMerge(left.pData, left.nData, right.pData, right.nData, &new);
dataBufferDestroy(&right);
dataBufferDestroy(&left);
left = new;
}
}
if( nNot==pQuery->nTerms ){
/* 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], &right);
if( rc ){
queryClear(pQuery);
dataBufferDestroy(&left);
return rc;
}
dataBufferInit(&new, 0);
docListExceptMerge(left.pData, left.nData, right.pData, right.nData, &new);
dataBufferDestroy(&right);
dataBufferDestroy(&left);
left = new;
}
*pResult = left;
return rc;
}
/*
** This is the xFilter interface for the virtual table. See
** the virtual table xFilter method documentation for additional
** information.
**
** If idxNum==QUERY_GENERIC then do a full table scan against
** the %_content table.
**
** If idxNum==QUERY_ROWID then do a rowid lookup for a single entry
** in the %_content table.
**
** If idxNum>=QUERY_FULLTEXT then use the full text index. The
** column on the left-hand side of the MATCH operator is column
** number idxNum-QUERY_FULLTEXT, 0 indexed. argv[0] is the right-hand
** side of the MATCH operator.
*/
/* TODO(shess) Upgrade the cursor initialization and destruction to
** account for fulltextFilter() being called multiple times on the
** same cursor. The current solution is very fragile. Apply fix to
** fts2 as appropriate.
*/
static int fulltextFilter(
sqlite3_vtab_cursor *pCursor, /* The cursor used for this query */
int idxNum, const char *idxStr, /* Which indexing scheme to use */
int argc, sqlite3_value **argv /* Arguments for the indexing scheme */
){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
fulltext_vtab *v = cursor_vtab(c);
int rc;
char *zSql;
TRACE(("FTS2 Filter %p\n",pCursor));
zSql = sqlite3_mprintf("select rowid, * from %%_content %s",
idxNum==QUERY_GENERIC ? "" : "where rowid=?");
sqlite3_finalize(c->pStmt);
rc = sql_prepare(v->db, v->zDb, v->zName, &c->pStmt, zSql);
sqlite3_free(zSql);
if( rc!=SQLITE_OK ) return rc;
c->iCursorType = idxNum;
switch( idxNum ){
case QUERY_GENERIC:
break;
case QUERY_ROWID:
rc = sqlite3_bind_int64(c->pStmt, 1, sqlite3_value_int64(argv[0]));
if( rc!=SQLITE_OK ) return rc;
break;
default: /* full-text search */
{
const char *zQuery = (const char *)sqlite3_value_text(argv[0]);
assert( idxNum<=QUERY_FULLTEXT+v->nColumn);
assert( argc==1 );
queryClear(&c->q);
if( c->result.nData!=0 ){
/* This case happens if the same cursor is used repeatedly. */
dlrDestroy(&c->reader);
dataBufferReset(&c->result);
}else{
dataBufferInit(&c->result, 0);
}
rc = fulltextQuery(v, idxNum-QUERY_FULLTEXT, zQuery, -1, &c->result, &c->q);
if( rc!=SQLITE_OK ) return rc;
if( c->result.nData!=0 ){
dlrInit(&c->reader, DL_DOCIDS, c->result.pData, c->result.nData);
}
break;
}
}
return fulltextNext(pCursor);
}
/* This is the xEof method of the virtual table. The SQLite core
** calls this routine to find out if it has reached the end of
** a query's results set.
*/
static int fulltextEof(sqlite3_vtab_cursor *pCursor){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
return c->eof;
}
/* This is the xColumn method of the virtual table. The SQLite
** core calls this method during a query when it needs the value
** of a column from the virtual table. This method needs to use
** one of the sqlite3_result_*() routines to store the requested
** value back in the pContext.
*/
static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
sqlite3_context *pContext, int idxCol){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
fulltext_vtab *v = cursor_vtab(c);
if( idxCol<v->nColumn ){
sqlite3_value *pVal = sqlite3_column_value(c->pStmt, idxCol+1);
sqlite3_result_value(pContext, pVal);
}else if( idxCol==v->nColumn ){
/* The extra column whose name is the same as the table.
** Return a blob which is a pointer to the cursor
*/
sqlite3_result_blob(pContext, &c, sizeof(c), SQLITE_TRANSIENT);
}
return SQLITE_OK;
}
/* This is the xRowid method. The SQLite core calls this routine to
** retrive the rowid for the current row of the result set. The
** rowid should be written to *pRowid.
*/
static int fulltextRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
*pRowid = sqlite3_column_int64(c->pStmt, 0);
return SQLITE_OK;
}
/* Add all terms in [zText] to the given hash table. If [iColumn] > 0,
* we also store positions and offsets in the hash table using the given
* column number. */
static int buildTerms(fulltext_vtab *v, 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) ){
PLWriter *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 = plwNew(iDocid, DL_DEFAULT);
fts2HashInsert(terms, pToken, nTokenBytes, p);
}
if( iColumn>=0 ){
plwAdd(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;
}
/* 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, rc;
/* TODO(shess) Should we allow such tables at all? */
if( DL_DEFAULT==DL_DOCIDS ) return SQLITE_ERROR;
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;
rc = content_update(v, pValues, iRow); /* execute an SQL UPDATE */
if( rc!=SQLITE_OK ) return rc;
/* Now add positions for terms which appear in the updated row. */
return insertTerms(v, pTerms, iRow, pValues);
}
/*******************************************************************/
/* InteriorWriter is used to collect terms and block references into
** interior nodes in %_segments. See commentary at top of file for
** format.
*/
/* How large interior nodes can grow. */
#define INTERIOR_MAX 2048
/* Minimum number of terms per interior node (except the root). This
** prevents large terms from making the tree too skinny - must be >0
** so that the tree always makes progress. Note that the min tree
** fanout will be INTERIOR_MIN_TERMS+1.
*/
#define INTERIOR_MIN_TERMS 7
#if INTERIOR_MIN_TERMS<1
# error INTERIOR_MIN_TERMS must be greater than 0.
#endif
/* ROOT_MAX controls how much data is stored inline in the segment
** directory.
*/
/* TODO(shess) Push ROOT_MAX down to whoever is writing things. It's
** only here so that interiorWriterRootInfo() and leafWriterRootInfo()
** can both see it, but if the caller passed it in, we wouldn't even
** need a define.
*/
#define ROOT_MAX 1024
#if ROOT_MAX<VARINT_MAX*2
# error ROOT_MAX must have enough space for a header.
#endif
/* InteriorBlock stores a linked-list of interior blocks while a lower
** layer is being constructed.
*/
typedef struct InteriorBlock {
DataBuffer term; /* Leftmost term in block's subtree. */
DataBuffer data; /* Accumulated data for the block. */
struct InteriorBlock *next;
} InteriorBlock;
static InteriorBlock *interiorBlockNew(int iHeight, sqlite_int64 iChildBlock,
const char *pTerm, int nTerm){
InteriorBlock *block = calloc(1, sizeof(InteriorBlock));
char c[VARINT_MAX+VARINT_MAX];
int n;
dataBufferInit(&block->term, 0);
dataBufferReplace(&block->term, pTerm, nTerm);
n = putVarint(c, iHeight);
n += putVarint(c+n, iChildBlock);
dataBufferInit(&block->data, INTERIOR_MAX);
dataBufferReplace(&block->data, c, n);
return block;
}
#ifndef NDEBUG
/* Verify that the data is readable as an interior node. */
static void interiorBlockValidate(InteriorBlock *pBlock){
const char *pData = pBlock->data.pData;
int nData = pBlock->data.nData;
int n, iDummy;
sqlite_int64 iBlockid;
assert( nData>0 );
assert( pData!=0 );
assert( pData+nData>pData );
/* Must lead with height of node as a varint(n), n>0 */
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n<nData );
pData += n;
nData -= n;
/* Must contain iBlockid. */
n = getVarint(pData, &iBlockid);
assert( n>0 );
assert( n<=nData );
pData += n;
nData -= n;
/* Zero or more terms of positive length */
if( nData!=0 ){
/* First term is not delta-encoded. */
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n+iDummy>0);
assert( n+iDummy<=nData );
pData += n+iDummy;
nData -= n+iDummy;
/* Following terms delta-encoded. */
while( nData!=0 ){
/* Length of shared prefix. */
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>=0 );
assert( n<nData );
pData += n;
nData -= n;
/* Length and data of distinct suffix. */
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n+iDummy>0);
assert( n+iDummy<=nData );
pData += n+iDummy;
nData -= n+iDummy;
}
}
}
#define ASSERT_VALID_INTERIOR_BLOCK(x) interiorBlockValidate(x)
#else
#define ASSERT_VALID_INTERIOR_BLOCK(x) assert( 1 )
#endif
typedef struct InteriorWriter {
int iHeight; /* from 0 at leaves. */
InteriorBlock *first, *last;
struct InteriorWriter *parentWriter;
DataBuffer term; /* Last term written to block "last". */
sqlite_int64 iOpeningChildBlock; /* First child block in block "last". */
#ifndef NDEBUG
sqlite_int64 iLastChildBlock; /* for consistency checks. */
#endif
} InteriorWriter;
/* Initialize an interior node where pTerm[nTerm] marks the leftmost
** term in the tree. iChildBlock is the leftmost child block at the
** next level down the tree.
*/
static void interiorWriterInit(int iHeight, const char *pTerm, int nTerm,
sqlite_int64 iChildBlock,
InteriorWriter *pWriter){
InteriorBlock *block;
assert( iHeight>0 );
CLEAR(pWriter);
pWriter->iHeight = iHeight;
pWriter->iOpeningChildBlock = iChildBlock;
#ifndef NDEBUG
pWriter->iLastChildBlock = iChildBlock;
#endif
block = interiorBlockNew(iHeight, iChildBlock, pTerm, nTerm);
pWriter->last = pWriter->first = block;
ASSERT_VALID_INTERIOR_BLOCK(pWriter->last);
dataBufferInit(&pWriter->term, 0);
}
/* Append the child node rooted at iChildBlock to the interior node,
** with pTerm[nTerm] as the leftmost term in iChildBlock's subtree.
*/
static void interiorWriterAppend(InteriorWriter *pWriter,
const char *pTerm, int nTerm,
sqlite_int64 iChildBlock){
char c[VARINT_MAX+VARINT_MAX];
int n, nPrefix = 0;
ASSERT_VALID_INTERIOR_BLOCK(pWriter->last);
/* The first term written into an interior node is actually
** associated with the second child added (the first child was added
** in interiorWriterInit, or in the if clause at the bottom of this
** function). That term gets encoded straight up, with nPrefix left
** at 0.
*/
if( pWriter->term.nData==0 ){
n = putVarint(c, nTerm);
}else{
while( nPrefix<pWriter->term.nData &&
pTerm[nPrefix]==pWriter->term.pData[nPrefix] ){
nPrefix++;
}
n = putVarint(c, nPrefix);
n += putVarint(c+n, nTerm-nPrefix);
}
#ifndef NDEBUG
pWriter->iLastChildBlock++;
#endif
assert( pWriter->iLastChildBlock==iChildBlock );
/* Overflow to a new block if the new term makes the current block
** too big, and the current block already has enough terms.
*/
if( pWriter->last->data.nData+n+nTerm-nPrefix>INTERIOR_MAX &&
iChildBlock-pWriter->iOpeningChildBlock>INTERIOR_MIN_TERMS ){
pWriter->last->next = interiorBlockNew(pWriter->iHeight, iChildBlock,
pTerm, nTerm);
pWriter->last = pWriter->last->next;
pWriter->iOpeningChildBlock = iChildBlock;
dataBufferReset(&pWriter->term);
}else{
dataBufferAppend2(&pWriter->last->data, c, n,
pTerm+nPrefix, nTerm-nPrefix);
dataBufferReplace(&pWriter->term, pTerm, nTerm);
}
ASSERT_VALID_INTERIOR_BLOCK(pWriter->last);
}
/* Free the space used by pWriter, including the linked-list of
** InteriorBlocks, and parentWriter, if present.
*/
static int interiorWriterDestroy(InteriorWriter *pWriter){
InteriorBlock *block = pWriter->first;
while( block!=NULL ){
InteriorBlock *b = block;
block = block->next;
dataBufferDestroy(&b->term);
dataBufferDestroy(&b->data);
free(b);
}
if( pWriter->parentWriter!=NULL ){
interiorWriterDestroy(pWriter->parentWriter);
free(pWriter->parentWriter);
}
dataBufferDestroy(&pWriter->term);
SCRAMBLE(pWriter);
return SQLITE_OK;
}
/* If pWriter can fit entirely in ROOT_MAX, return it as the root info
** directly, leaving *piEndBlockid unchanged. Otherwise, flush
** pWriter to %_segments, building a new layer of interior nodes, and
** recursively ask for their root into.
*/
static int interiorWriterRootInfo(fulltext_vtab *v, InteriorWriter *pWriter,
char **ppRootInfo, int *pnRootInfo,
sqlite_int64 *piEndBlockid){
InteriorBlock *block = pWriter->first;
sqlite_int64 iBlockid = 0;
int rc;
/* If we can fit the segment inline */
if( block==pWriter->last && block->data.nData<ROOT_MAX ){
*ppRootInfo = block->data.pData;
*pnRootInfo = block->data.nData;
return SQLITE_OK;
}
/* Flush the first block to %_segments, and create a new level of
** interior node.
*/
ASSERT_VALID_INTERIOR_BLOCK(block);
rc = block_insert(v, block->data.pData, block->data.nData, &iBlockid);
if( rc!=SQLITE_OK ) return rc;
*piEndBlockid = iBlockid;
pWriter->parentWriter = malloc(sizeof(*pWriter->parentWriter));
interiorWriterInit(pWriter->iHeight+1,
block->term.pData, block->term.nData,
iBlockid, pWriter->parentWriter);
/* Flush additional blocks and append to the higher interior
** node.
*/
for(block=block->next; block!=NULL; block=block->next){
ASSERT_VALID_INTERIOR_BLOCK(block);
rc = block_insert(v, block->data.pData, block->data.nData, &iBlockid);
if( rc!=SQLITE_OK ) return rc;
*piEndBlockid = iBlockid;
interiorWriterAppend(pWriter->parentWriter,
block->term.pData, block->term.nData, iBlockid);
}
/* Parent node gets the chance to be the root. */
return interiorWriterRootInfo(v, pWriter->parentWriter,
ppRootInfo, pnRootInfo, piEndBlockid);
}
/****************************************************************/
/* InteriorReader is used to read off the data from an interior node
** (see comment at top of file for the format).
*/
typedef struct InteriorReader {
const char *pData;
int nData;
DataBuffer term; /* previous term, for decoding term delta. */
sqlite_int64 iBlockid;
} InteriorReader;
static void interiorReaderDestroy(InteriorReader *pReader){
SCRAMBLE(pReader);
}
static void interiorReaderInit(const char *pData, int nData,
InteriorReader *pReader){
int n, nTerm;
/* Require at least the leading flag byte */
assert( nData>0 );
assert( pData[0]!='\0' );
CLEAR(pReader);
/* Decode the base blockid, and set the cursor to the first term. */
n = getVarint(pData+1, &pReader->iBlockid);
assert( 1+n<=nData );
pReader->pData = pData+1+n;
pReader->nData = nData-(1+n);
/* A single-child interior node (such as when a leaf node was too
** large for the segment directory) won't have any terms.
** Otherwise, decode the first term.
*/
if( pReader->nData==0 ){
dataBufferInit(&pReader->term, 0);
}else{
n = getVarint32(pReader->pData, &nTerm);
dataBufferInit(&pReader->term, nTerm);
dataBufferReplace(&pReader->term, pReader->pData+n, nTerm);
assert( n+nTerm<=pReader->nData );
pReader->pData += n+nTerm;
pReader->nData -= n+nTerm;
}
}
static int interiorReaderAtEnd(InteriorReader *pReader){
return pReader->term.nData==0;
}
static sqlite_int64 interiorReaderCurrentBlockid(InteriorReader *pReader){
return pReader->iBlockid;
}
static int interiorReaderTermBytes(InteriorReader *pReader){
assert( !interiorReaderAtEnd(pReader) );
return pReader->term.nData;
}
static const char *interiorReaderTerm(InteriorReader *pReader){
assert( !interiorReaderAtEnd(pReader) );
return pReader->term.pData;
}
/* Step forward to the next term in the node. */
static void interiorReaderStep(InteriorReader *pReader){
assert( !interiorReaderAtEnd(pReader) );
/* If the last term has been read, signal eof, else construct the
** next term.
*/
if( pReader->nData==0 ){
dataBufferReset(&pReader->term);
}else{
int n, nPrefix, nSuffix;
n = getVarint32(pReader->pData, &nPrefix);
n += getVarint32(pReader->pData+n, &nSuffix);
/* Truncate the current term and append suffix data. */
pReader->term.nData = nPrefix;
dataBufferAppend(&pReader->term, pReader->pData+n, nSuffix);
assert( n+nSuffix<=pReader->nData );
pReader->pData += n+nSuffix;
pReader->nData -= n+nSuffix;
}
pReader->iBlockid++;
}
/* Compare the current term to pTerm[nTerm], returning strcmp-style
** results.
*/
static int interiorReaderTermCmp(InteriorReader *pReader,
const char *pTerm, int nTerm){
const char *pReaderTerm = interiorReaderTerm(pReader);
int nReaderTerm = interiorReaderTermBytes(pReader);
int c, n = nReaderTerm<nTerm ? nReaderTerm : nTerm;
if( n==0 ){
if( nReaderTerm>0 ) return -1;
if( nTerm>0 ) return 1;
return 0;
}
c = memcmp(pReaderTerm, pTerm, n);
if( c!=0 ) return c;
return nReaderTerm - nTerm;
}
/****************************************************************/
/* LeafWriter is used to collect terms and associated doclist data
** into leaf blocks in %_segments (see top of file for format info).
** Expected usage is:
**
** LeafWriter writer;
** leafWriterInit(0, 0, &writer);
** while( sorted_terms_left_to_process ){
** // data is doclist data for that term.
** rc = leafWriterStep(v, &writer, pTerm, nTerm, pData, nData);
** if( rc!=SQLITE_OK ) goto err;
** }
** rc = leafWriterFinalize(v, &writer);
**err:
** leafWriterDestroy(&writer);
** return rc;
**
** leafWriterStep() may write a collected leaf out to %_segments.
** leafWriterFinalize() finishes writing any buffered data and stores
** a root node in %_segdir. leafWriterDestroy() frees all buffers and
** InteriorWriters allocated as part of writing this segment.
**
** TODO(shess) Document leafWriterStepMerge().
*/
/* Put terms with data this big in their own block. */
#define STANDALONE_MIN 1024
/* Keep leaf blocks below this size. */
#define LEAF_MAX 2048
typedef struct LeafWriter {
int iLevel;
int idx;
sqlite_int64 iStartBlockid; /* needed to create the root info */
sqlite_int64 iEndBlockid; /* when we're done writing. */
DataBuffer term; /* previous encoded term */
DataBuffer data; /* encoding buffer */
/* bytes of first term in the current node which distinguishes that
** term from the last term of the previous node.
*/
int nTermDistinct;
InteriorWriter parentWriter; /* if we overflow */
int has_parent;
} LeafWriter;
static void leafWriterInit(int iLevel, int idx, LeafWriter *pWriter){
CLEAR(pWriter);
pWriter->iLevel = iLevel;
pWriter->idx = idx;
dataBufferInit(&pWriter->term, 32);
/* Start out with a reasonably sized block, though it can grow. */
dataBufferInit(&pWriter->data, LEAF_MAX);
}
#ifndef NDEBUG
/* Verify that the data is readable as a leaf node. */
static void leafNodeValidate(const char *pData, int nData){
int n, iDummy;
if( nData==0 ) return;
assert( nData>0 );
assert( pData!=0 );
assert( pData+nData>pData );
/* Must lead with a varint(0) */
n = getVarint32(pData, &iDummy);
assert( iDummy==0 );
assert( n>0 );
assert( n<nData );
pData += n;
nData -= n;
/* Leading term length and data must fit in buffer. */
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n+iDummy>0 );
assert( n+iDummy<nData );
pData += n+iDummy;
nData -= n+iDummy;
/* Leading term's doclist length and data must fit. */
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n+iDummy>0 );
assert( n+iDummy<=nData );
ASSERT_VALID_DOCLIST(DL_DEFAULT, pData+n, iDummy, NULL);
pData += n+iDummy;
nData -= n+iDummy;
/* Verify that trailing terms and doclists also are readable. */
while( nData!=0 ){
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>=0 );
assert( n<nData );
pData += n;
nData -= n;
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n+iDummy>0 );
assert( n+iDummy<nData );
pData += n+iDummy;
nData -= n+iDummy;
n = getVarint32(pData, &iDummy);
assert( n>0 );
assert( iDummy>0 );
assert( n+iDummy>0 );
assert( n+iDummy<=nData );
ASSERT_VALID_DOCLIST(DL_DEFAULT, pData+n, iDummy, NULL);
pData += n+iDummy;
nData -= n+iDummy;
}
}
#define ASSERT_VALID_LEAF_NODE(p, n) leafNodeValidate(p, n)
#else
#define ASSERT_VALID_LEAF_NODE(p, n) assert( 1 )
#endif
/* Flush the current leaf node to %_segments, and adding the resulting
** blockid and the starting term to the interior node which will
** contain it.
*/
static int leafWriterInternalFlush(fulltext_vtab *v, LeafWriter *pWriter,
int iData, int nData){
sqlite_int64 iBlockid = 0;
const char *pStartingTerm;
int nStartingTerm, rc, n;
/* Must have the leading varint(0) flag, plus at least some
** valid-looking data.
*/
assert( nData>2 );
assert( iData>=0 );
assert( iData+nData<=pWriter->data.nData );
ASSERT_VALID_LEAF_NODE(pWriter->data.pData+iData, nData);
rc = block_insert(v, pWriter->data.pData+iData, nData, &iBlockid);
if( rc!=SQLITE_OK ) return rc;
assert( iBlockid!=0 );
/* Reconstruct the first term in the leaf for purposes of building
** the interior node.
*/
n = getVarint32(pWriter->data.pData+iData+1, &nStartingTerm);
pStartingTerm = pWriter->data.pData+iData+1+n;
assert( pWriter->data.nData>iData+1+n+nStartingTerm );
assert( pWriter->nTermDistinct>0 );
assert( pWriter->nTermDistinct<=nStartingTerm );
nStartingTerm = pWriter->nTermDistinct;
if( pWriter->has_parent ){
interiorWriterAppend(&pWriter->parentWriter,
pStartingTerm, nStartingTerm, iBlockid);
}else{
interiorWriterInit(1, pStartingTerm, nStartingTerm, iBlockid,
&pWriter->parentWriter);
pWriter->has_parent = 1;
}
/* Track the span of this segment's leaf nodes. */
if( pWriter->iEndBlockid==0 ){
pWriter->iEndBlockid = pWriter->iStartBlockid = iBlockid;
}else{
pWriter->iEndBlockid++;
assert( iBlockid==pWriter->iEndBlockid );
}
return SQLITE_OK;
}
static int leafWriterFlush(fulltext_vtab *v, LeafWriter *pWriter){
int rc = leafWriterInternalFlush(v, pWriter, 0, pWriter->data.nData);
if( rc!=SQLITE_OK ) return rc;
/* Re-initialize the output buffer. */
dataBufferReset(&pWriter->data);
return SQLITE_OK;
}
/* Fetch the root info for the segment. If the entire leaf fits
** within ROOT_MAX, then it will be returned directly, otherwise it
** will be flushed and the root info will be returned from the
** interior node. *piEndBlockid is set to the blockid of the last
** interior or leaf node written to disk (0 if none are written at
** all).
*/
static int leafWriterRootInfo(fulltext_vtab *v, LeafWriter *pWriter,
char **ppRootInfo, int *pnRootInfo,
sqlite_int64 *piEndBlockid){
/* we can fit the segment entirely inline */
if( !pWriter->has_parent && pWriter->data.nData<ROOT_MAX ){
*ppRootInfo = pWriter->data.pData;
*pnRootInfo = pWriter->data.nData;
*piEndBlockid = 0;
return SQLITE_OK;
}
/* Flush remaining leaf data. */
if( pWriter->data.nData>0 ){
int rc = leafWriterFlush(v, pWriter);
if( rc!=SQLITE_OK ) return rc;
}
/* We must have flushed a leaf at some point. */
assert( pWriter->has_parent );
/* Tenatively set the end leaf blockid as the end blockid. If the
** interior node can be returned inline, this will be the final
** blockid, otherwise it will be overwritten by
** interiorWriterRootInfo().
*/
*piEndBlockid = pWriter->iEndBlockid;
return interiorWriterRootInfo(v, &pWriter->parentWriter,
ppRootInfo, pnRootInfo, piEndBlockid);
}
/* Collect the rootInfo data and store it into the segment directory.
** This has the effect of flushing the segment's leaf data to
** %_segments, and also flushing any interior nodes to %_segments.
*/
static int leafWriterFinalize(fulltext_vtab *v, LeafWriter *pWriter){
sqlite_int64 iEndBlockid;
char *pRootInfo;
int rc, nRootInfo;
rc = leafWriterRootInfo(v, pWriter, &pRootInfo, &nRootInfo, &iEndBlockid);
if( rc!=SQLITE_OK ) return rc;
/* Don't bother storing an entirely empty segment. */
if( iEndBlockid==0 && nRootInfo==0 ) return SQLITE_OK;
return segdir_set(v, pWriter->iLevel, pWriter->idx,
pWriter->iStartBlockid, pWriter->iEndBlockid,
iEndBlockid, pRootInfo, nRootInfo);
}
static void leafWriterDestroy(LeafWriter *pWriter){
if( pWriter->has_parent ) interiorWriterDestroy(&pWriter->parentWriter);
dataBufferDestroy(&pWriter->term);
dataBufferDestroy(&pWriter->data);
}
/* Encode a term into the leafWriter, delta-encoding as appropriate.
** Returns the length of the new term which distinguishes it from the
** previous term, which can be used to set nTermDistinct when a node
** boundary is crossed.
*/
static int leafWriterEncodeTerm(LeafWriter *pWriter,
const char *pTerm, int nTerm){
char c[VARINT_MAX+VARINT_MAX];
int n, nPrefix = 0;
assert( nTerm>0 );
while( nPrefix<pWriter->term.nData &&
pTerm[nPrefix]==pWriter->term.pData[nPrefix] ){
nPrefix++;
/* Failing this implies that the terms weren't in order. */
assert( nPrefix<nTerm );
}
if( pWriter->data.nData==0 ){
/* Encode the node header and leading term as:
** varint(0)
** varint(nTerm)
** char pTerm[nTerm]
*/
n = putVarint(c, '\0');
n += putVarint(c+n, nTerm);
dataBufferAppend2(&pWriter->data, c, n, pTerm, nTerm);
}else{
/* Delta-encode the term as:
** varint(nPrefix)
** varint(nSuffix)
** char pTermSuffix[nSuffix]
*/
n = putVarint(c, nPrefix);
n += putVarint(c+n, nTerm-nPrefix);
dataBufferAppend2(&pWriter->data, c, n, pTerm+nPrefix, nTerm-nPrefix);
}
dataBufferReplace(&pWriter->term, pTerm, nTerm);
return nPrefix+1;
}
/* Used to avoid a memmove when a large amount of doclist data is in
** the buffer. This constructs a node and term header before
** iDoclistData and flushes the resulting complete node using
** leafWriterInternalFlush().
*/
static int leafWriterInlineFlush(fulltext_vtab *v, LeafWriter *pWriter,
const char *pTerm, int nTerm,
int iDoclistData){
char c[VARINT_MAX+VARINT_MAX];
int iData, n = putVarint(c, 0);
n += putVarint(c+n, nTerm);
/* There should always be room for the header. Even if pTerm shared
** a substantial prefix with the previous term, the entire prefix
** could be constructed from earlier data in the doclist, so there
** should be room.
*/
assert( iDoclistData>=n+nTerm );
iData = iDoclistData-(n+nTerm);
memcpy(pWriter->data.pData+iData, c, n);
memcpy(pWriter->data.pData+iData+n, pTerm, nTerm);
return leafWriterInternalFlush(v, pWriter, iData, pWriter->data.nData-iData);
}
/* Push pTerm[nTerm] along with the doclist data to the leaf layer of
** %_segments.
*/
static int leafWriterStepMerge(fulltext_vtab *v, LeafWriter *pWriter,
const char *pTerm, int nTerm,
DLReader *pReaders, int nReaders){
char c[VARINT_MAX+VARINT_MAX];
int iTermData = pWriter->data.nData, iDoclistData;
int i, nData, n, nActualData, nActual, rc, nTermDistinct;
ASSERT_VALID_LEAF_NODE(pWriter->data.pData, pWriter->data.nData);
nTermDistinct = leafWriterEncodeTerm(pWriter, pTerm, nTerm);
/* Remember nTermDistinct if opening a new node. */
if( iTermData==0 ) pWriter->nTermDistinct = nTermDistinct;
iDoclistData = pWriter->data.nData;
/* Estimate the length of the merged doclist so we can leave space
** to encode it.
*/
for(i=0, nData=0; i<nReaders; i++){
nData += dlrAllDataBytes(&pReaders[i]);
}
n = putVarint(c, nData);
dataBufferAppend(&pWriter->data, c, n);
docListMerge(&pWriter->data, pReaders, nReaders);
ASSERT_VALID_DOCLIST(DL_DEFAULT,
pWriter->data.pData+iDoclistData+n,
pWriter->data.nData-iDoclistData-n, NULL);
/* The actual amount of doclist data at this point could be smaller
** than the length we encoded. Additionally, the space required to
** encode this length could be smaller. For small doclists, this is
** not a big deal, we can just use memmove() to adjust things.
*/
nActualData = pWriter->data.nData-(iDoclistData+n);
nActual = putVarint(c, nActualData);
assert( nActualData<=nData );
assert( nActual<=n );
/* If the new doclist is big enough for force a standalone leaf
** node, we can immediately flush it inline without doing the
** memmove().
*/
/* TODO(shess) This test matches leafWriterStep(), which does this
** test before it knows the cost to varint-encode the term and
** doclist lengths. At some point, change to
** pWriter->data.nData-iTermData>STANDALONE_MIN.
*/
if( nTerm+nActualData>STANDALONE_MIN ){
/* Push leaf node from before this term. */
if( iTermData>0 ){
rc = leafWriterInternalFlush(v, pWriter, 0, iTermData);
if( rc!=SQLITE_OK ) return rc;
pWriter->nTermDistinct = nTermDistinct;
}
/* Fix the encoded doclist length. */
iDoclistData += n - nActual;
memcpy(pWriter->data.pData+iDoclistData, c, nActual);
/* Push the standalone leaf node. */
rc = leafWriterInlineFlush(v, pWriter, pTerm, nTerm, iDoclistData);
if( rc!=SQLITE_OK ) return rc;
/* Leave the node empty. */
dataBufferReset(&pWriter->data);
return rc;
}
/* At this point, we know that the doclist was small, so do the
** memmove if indicated.
*/
if( nActual<n ){
memmove(pWriter->data.pData+iDoclistData+nActual,
pWriter->data.pData+iDoclistData+n,
pWriter->data.nData-(iDoclistData+n));
pWriter->data.nData -= n-nActual;
}
/* Replace written length with actual length. */
memcpy(pWriter->data.pData+iDoclistData, c, nActual);
/* If the node is too large, break things up. */
/* TODO(shess) This test matches leafWriterStep(), which does this
** test before it knows the cost to varint-encode the term and
** doclist lengths. At some point, change to
** pWriter->data.nData>LEAF_MAX.
*/
if( iTermData+nTerm+nActualData>LEAF_MAX ){
/* Flush out the leading data as a node */
rc = leafWriterInternalFlush(v, pWriter, 0, iTermData);
if( rc!=SQLITE_OK ) return rc;
pWriter->nTermDistinct = nTermDistinct;
/* Rebuild header using the current term */
n = putVarint(pWriter->data.pData, 0);
n += putVarint(pWriter->data.pData+n, nTerm);
memcpy(pWriter->data.pData+n, pTerm, nTerm);
n += nTerm;
/* There should always be room, because the previous encoding
** included all data necessary to construct the term.
*/
assert( n<iDoclistData );
/* So long as STANDALONE_MIN is half or less of LEAF_MAX, the
** following memcpy() is safe (as opposed to needing a memmove).
*/
assert( 2*STANDALONE_MIN<=LEAF_MAX );
assert( n+pWriter->data.nData-iDoclistData<iDoclistData );
memcpy(pWriter->data.pData+n,
pWriter->data.pData+iDoclistData,
pWriter->data.nData-iDoclistData);
pWriter->data.nData -= iDoclistData-n;
}
ASSERT_VALID_LEAF_NODE(pWriter->data.pData, pWriter->data.nData);
return SQLITE_OK;
}
/* Push pTerm[nTerm] along with the doclist data to the leaf layer of
** %_segments.
*/
/* TODO(shess) Revise writeZeroSegment() so that doclists are
** constructed directly in pWriter->data.
*/
static int leafWriterStep(fulltext_vtab *v, LeafWriter *pWriter,
const char *pTerm, int nTerm,
const char *pData, int nData){
int rc;
DLReader reader;
dlrInit(&reader, DL_DEFAULT, pData, nData);
rc = leafWriterStepMerge(v, pWriter, pTerm, nTerm, &reader, 1);
dlrDestroy(&reader);
return rc;
}
/****************************************************************/
/* LeafReader is used to iterate over an individual leaf node. */
typedef struct LeafReader {
DataBuffer term; /* copy of current term. */
const char *pData; /* data for current term. */
int nData;
} LeafReader;
static void leafReaderDestroy(LeafReader *pReader){
dataBufferDestroy(&pReader->term);
SCRAMBLE(pReader);
}
static int leafReaderAtEnd(LeafReader *pReader){
return pReader->nData<=0;
}
/* Access the current term. */
static int leafReaderTermBytes(LeafReader *pReader){
return pReader->term.nData;
}
static const char *leafReaderTerm(LeafReader *pReader){
assert( pReader->term.nData>0 );
return pReader->term.pData;
}
/* Access the doclist data for the current term. */
static int leafReaderDataBytes(LeafReader *pReader){
int nData;
assert( pReader->term.nData>0 );
getVarint32(pReader->pData, &nData);
return nData;
}
static const char *leafReaderData(LeafReader *pReader){
int n, nData;
assert( pReader->term.nData>0 );
n = getVarint32(pReader->pData, &nData);
return pReader->pData+n;
}
static void leafReaderInit(const char *pData, int nData,
LeafReader *pReader){
int nTerm, n;
assert( nData>0 );
assert( pData[0]=='\0' );
CLEAR(pReader);
/* Read the first term, skipping the header byte. */
n = getVarint32(pData+1, &nTerm);
dataBufferInit(&pReader->term, nTerm);
dataBufferReplace(&pReader->term, pData+1+n, nTerm);
/* Position after the first term. */
assert( 1+n+nTerm<nData );
pReader->pData = pData+1+n+nTerm;
pReader->nData = nData-1-n-nTerm;
}
/* Step the reader forward to the next term. */
static void leafReaderStep(LeafReader *pReader){
int n, nData, nPrefix, nSuffix;
assert( !leafReaderAtEnd(pReader) );
/* Skip previous entry's data block. */
n = getVarint32(pReader->pData, &nData);
assert( n+nData<=pReader->nData );
pReader->pData += n+nData;
pReader->nData -= n+nData;
if( !leafReaderAtEnd(pReader) ){
/* Construct the new term using a prefix from the old term plus a
** suffix from the leaf data.
*/
n = getVarint32(pReader->pData, &nPrefix);
n += getVarint32(pReader->pData+n, &nSuffix);
assert( n+nSuffix<pReader->nData );
pReader->term.nData = nPrefix;
dataBufferAppend(&pReader->term, pReader->pData+n, nSuffix);
pReader->pData += n+nSuffix;
pReader->nData -= n+nSuffix;
}
}
/* strcmp-style comparison of pReader's current term against pTerm. */
static int leafReaderTermCmp(LeafReader *pReader,
const char *pTerm, int nTerm){
int c, n = pReader->term.nData<nTerm ? pReader->term.nData : nTerm;
if( n==0 ){
if( pReader->term.nData>0 ) return -1;
if(nTerm>0 ) return 1;
return 0;
}
c = memcmp(pReader->term.pData, pTerm, n);
if( c!=0 ) return c;
return pReader->term.nData - nTerm;
}
/****************************************************************/
/* LeavesReader wraps LeafReader to allow iterating over the entire
** leaf layer of the tree.
*/
typedef struct LeavesReader {
int idx; /* Index within the segment. */
sqlite3_stmt *pStmt; /* Statement we're streaming leaves from. */
int eof; /* we've seen SQLITE_DONE from pStmt. */
LeafReader leafReader; /* reader for the current leaf. */
DataBuffer rootData; /* root data for inline. */
} LeavesReader;
/* Access the current term. */
static int leavesReaderTermBytes(LeavesReader *pReader){
assert( !pReader->eof );
return leafReaderTermBytes(&pReader->leafReader);
}
static const char *leavesReaderTerm(LeavesReader *pReader){
assert( !pReader->eof );
return leafReaderTerm(&pReader->leafReader);
}
/* Access the doclist data for the current term. */
static int leavesReaderDataBytes(LeavesReader *pReader){
assert( !pReader->eof );
return leafReaderDataBytes(&pReader->leafReader);
}
static const char *leavesReaderData(LeavesReader *pReader){
assert( !pReader->eof );
return leafReaderData(&pReader->leafReader);
}
static int leavesReaderAtEnd(LeavesReader *pReader){
return pReader->eof;
}
static void leavesReaderDestroy(LeavesReader *pReader){
leafReaderDestroy(&pReader->leafReader);
dataBufferDestroy(&pReader->rootData);
SCRAMBLE(pReader);
}
/* Initialize pReader with the given root data (if iStartBlockid==0
** the leaf data was entirely contained in the root), or from the
** stream of blocks between iStartBlockid and iEndBlockid, inclusive.
*/
static int leavesReaderInit(fulltext_vtab *v,
int idx,
sqlite_int64 iStartBlockid,
sqlite_int64 iEndBlockid,
const char *pRootData, int nRootData,
LeavesReader *pReader){
CLEAR(pReader);
pReader->idx = idx;
dataBufferInit(&pReader->rootData, 0);
if( iStartBlockid==0 ){
/* Entire leaf level fit in root data. */
dataBufferReplace(&pReader->rootData, pRootData, nRootData);
leafReaderInit(pReader->rootData.pData, pReader->rootData.nData,
&pReader->leafReader);
}else{
sqlite3_stmt *s;
int rc = sql_get_leaf_statement(v, idx, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 1, iStartBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 2, iEndBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_leaf_statement(v, idx, &s);
if( rc==SQLITE_DONE ){
pReader->eof = 1;
return SQLITE_OK;
}
if( rc!=SQLITE_ROW ) return rc;
pReader->pStmt = s;
leafReaderInit(sqlite3_column_blob(pReader->pStmt, 0),
sqlite3_column_bytes(pReader->pStmt, 0),
&pReader->leafReader);
}
return SQLITE_OK;
}
/* Step the current leaf forward to the next term. If we reach the
** end of the current leaf, step forward to the next leaf block.
*/
static int leavesReaderStep(fulltext_vtab *v, LeavesReader *pReader){
assert( !leavesReaderAtEnd(pReader) );
leafReaderStep(&pReader->leafReader);
if( leafReaderAtEnd(&pReader->leafReader) ){
int rc;
if( pReader->rootData.pData ){
pReader->eof = 1;
return SQLITE_OK;
}
rc = sql_step_leaf_statement(v, pReader->idx, &pReader->pStmt);
if( rc!=SQLITE_ROW ){
pReader->eof = 1;
return rc==SQLITE_DONE ? SQLITE_OK : rc;
}
leafReaderDestroy(&pReader->leafReader);
leafReaderInit(sqlite3_column_blob(pReader->pStmt, 0),
sqlite3_column_bytes(pReader->pStmt, 0),
&pReader->leafReader);
}
return SQLITE_OK;
}
/* Order LeavesReaders by their term, ignoring idx. Readers at eof
** always sort to the end.
*/
static int leavesReaderTermCmp(LeavesReader *lr1, LeavesReader *lr2){
if( leavesReaderAtEnd(lr1) ){
if( leavesReaderAtEnd(lr2) ) return 0;
return 1;
}
if( leavesReaderAtEnd(lr2) ) return -1;
return leafReaderTermCmp(&lr1->leafReader,
leavesReaderTerm(lr2), leavesReaderTermBytes(lr2));
}
/* Similar to leavesReaderTermCmp(), with additional ordering by idx
** so that older segments sort before newer segments.
*/
static int leavesReaderCmp(LeavesReader *lr1, LeavesReader *lr2){
int c = leavesReaderTermCmp(lr1, lr2);
if( c!=0 ) return c;
return lr1->idx-lr2->idx;
}
/* Assume that pLr[1]..pLr[nLr] are sorted. Bubble pLr[0] into its
** sorted position.
*/
static void leavesReaderReorder(LeavesReader *pLr, int nLr){
while( nLr>1 && leavesReaderCmp(pLr, pLr+1)>0 ){
LeavesReader tmp = pLr[0];
pLr[0] = pLr[1];
pLr[1] = tmp;
nLr--;
pLr++;
}
}
/* Initializes pReaders with the segments from level iLevel, returning
** the number of segments in *piReaders. Leaves pReaders in sorted
** order.
*/
static int leavesReadersInit(fulltext_vtab *v, int iLevel,
LeavesReader *pReaders, int *piReaders){
sqlite3_stmt *s;
int i, rc = sql_get_statement(v, SEGDIR_SELECT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int(s, 1, iLevel);
if( rc!=SQLITE_OK ) return rc;
i = 0;
while( (rc = sql_step_statement(v, SEGDIR_SELECT_STMT, &s))==SQLITE_ROW ){
sqlite_int64 iStart = sqlite3_column_int64(s, 0);
sqlite_int64 iEnd = sqlite3_column_int64(s, 1);
const char *pRootData = sqlite3_column_blob(s, 2);
int nRootData = sqlite3_column_bytes(s, 2);
assert( i<MERGE_COUNT );
rc = leavesReaderInit(v, i, iStart, iEnd, pRootData, nRootData,
&pReaders[i]);
if( rc!=SQLITE_OK ) break;
i++;
}
if( rc!=SQLITE_DONE ){
while( i-->0 ){
leavesReaderDestroy(&pReaders[i]);
}
return rc;
}
*piReaders = i;
/* Leave our results sorted by term, then age. */
while( i-- ){
leavesReaderReorder(pReaders+i, *piReaders-i);
}
return SQLITE_OK;
}
/* Merge doclists from pReaders[nReaders] into a single doclist, which
** is written to pWriter. Assumes pReaders is ordered oldest to
** newest.
*/
/* TODO(shess) Consider putting this inline in segmentMerge(). */
static int leavesReadersMerge(fulltext_vtab *v,
LeavesReader *pReaders, int nReaders,
LeafWriter *pWriter){
DLReader dlReaders[MERGE_COUNT];
const char *pTerm = leavesReaderTerm(pReaders);
int i, nTerm = leavesReaderTermBytes(pReaders);
assert( nReaders<=MERGE_COUNT );
for(i=0; i<nReaders; i++){
dlrInit(&dlReaders[i], DL_DEFAULT,
leavesReaderData(pReaders+i),
leavesReaderDataBytes(pReaders+i));
}
return leafWriterStepMerge(v, pWriter, pTerm, nTerm, dlReaders, nReaders);
}
/* Forward ref due to mutual recursion with segdirNextIndex(). */
static int segmentMerge(fulltext_vtab *v, int iLevel);
/* Put the next available index at iLevel into *pidx. If iLevel
** already has MERGE_COUNT segments, they are merged to a higher
** level to make room.
*/
static int segdirNextIndex(fulltext_vtab *v, int iLevel, int *pidx){
int rc = segdir_max_index(v, iLevel, pidx);
if( rc==SQLITE_DONE ){ /* No segments at iLevel. */
*pidx = 0;
}else if( rc==SQLITE_ROW ){
if( *pidx==(MERGE_COUNT-1) ){
rc = segmentMerge(v, iLevel);
if( rc!=SQLITE_OK ) return rc;
*pidx = 0;
}else{
(*pidx)++;
}
}else{
return rc;
}
return SQLITE_OK;
}
/* Merge MERGE_COUNT segments at iLevel into a new segment at
** iLevel+1. If iLevel+1 is already full of segments, those will be
** merged to make room.
*/
static int segmentMerge(fulltext_vtab *v, int iLevel){
LeafWriter writer;
LeavesReader lrs[MERGE_COUNT];
int i, rc, idx = 0;
/* Determine the next available segment index at the next level,
** merging as necessary.
*/
rc = segdirNextIndex(v, iLevel+1, &idx);
if( rc!=SQLITE_OK ) return rc;
/* TODO(shess) This assumes that we'll always see exactly
** MERGE_COUNT segments to merge at a given level. That will be
** broken if we allow the developer to request preemptive or
** deferred merging.
*/
memset(&lrs, '\0', sizeof(lrs));
rc = leavesReadersInit(v, iLevel, lrs, &i);
if( rc!=SQLITE_OK ) return rc;
assert( i==MERGE_COUNT );
leafWriterInit(iLevel+1, idx, &writer);
/* Since leavesReaderReorder() pushes readers at eof to the end,
** when the first reader is empty, all will be empty.
*/
while( !leavesReaderAtEnd(lrs) ){
/* Figure out how many readers share their next term. */
for(i=1; i<MERGE_COUNT && !leavesReaderAtEnd(lrs+i); i++){
if( 0!=leavesReaderTermCmp(lrs, lrs+i) ) break;
}
rc = leavesReadersMerge(v, lrs, i, &writer);
if( rc!=SQLITE_OK ) goto err;
/* Step forward those that were merged. */
while( i-->0 ){
rc = leavesReaderStep(v, lrs+i);
if( rc!=SQLITE_OK ) goto err;
/* Reorder by term, then by age. */
leavesReaderReorder(lrs+i, MERGE_COUNT-i);
}
}
for(i=0; i<MERGE_COUNT; i++){
leavesReaderDestroy(&lrs[i]);
}
rc = leafWriterFinalize(v, &writer);
leafWriterDestroy(&writer);
if( rc!=SQLITE_OK ) return rc;
/* Delete the merged segment data. */
return segdir_delete(v, iLevel);
err:
for(i=0; i<MERGE_COUNT; i++){
leavesReaderDestroy(&lrs[i]);
}
leafWriterDestroy(&writer);
return rc;
}
/* Read pData[nData] as a leaf node, and if the doclist for
** pTerm[nTerm] is present, merge it over *out (any duplicate doclists
** read from pData will overwrite those in *out).
*/
static int loadSegmentLeaf(fulltext_vtab *v, const char *pData, int nData,
const char *pTerm, int nTerm, DataBuffer *out){
LeafReader reader;
assert( nData>1 );
assert( *pData=='\0' );
leafReaderInit(pData, nData, &reader);
while( !leafReaderAtEnd(&reader) ){
int c = leafReaderTermCmp(&reader, pTerm, nTerm);
if( c==0 ){
if( out->nData==0 ){
dataBufferReplace(out,
leafReaderData(&reader), leafReaderDataBytes(&reader));
}else{
DLReader readers[2];
DataBuffer result;
dlrInit(&readers[0], DL_DEFAULT, out->pData, out->nData);
dlrInit(&readers[1], DL_DEFAULT,
leafReaderData(&reader), leafReaderDataBytes(&reader));
dataBufferInit(&result, out->nData+leafReaderDataBytes(&reader));
docListMerge(&result, readers, 2);
dataBufferDestroy(out);
*out = result;
}
}
if( c>=0 ) break;
leafReaderStep(&reader);
}
leafReaderDestroy(&reader);
return SQLITE_OK;
}
/* Traverse the tree represented by pData[nData] looking for
** pTerm[nTerm], merging its doclist over *out if found (any duplicate
** doclists read from the segment rooted at pData will overwrite those
** in *out).
*/
static int loadSegment(fulltext_vtab *v, const char *pData, int nData,
const char *pTerm, int nTerm, DataBuffer *out){
int rc;
sqlite3_stmt *s = NULL;
assert( nData>1 );
/* Process data as an interior node until we reach a leaf. */
while( *pData!='\0' ){
sqlite_int64 iBlockid;
InteriorReader reader;
/* Scan the node data until we find a term greater than our term.
** Our target child will be in the blockid under that term, or in
** the last blockid in the node if we never find such a term.
*/
interiorReaderInit(pData, nData, &reader);
while( !interiorReaderAtEnd(&reader) ){
if( interiorReaderTermCmp(&reader, pTerm, nTerm)>0 ) break;
interiorReaderStep(&reader);
}
/* Grab the child blockid before calling sql_get_statement(),
** because sql_get_statement() may reset our data out from under
** us.
*/
iBlockid = interiorReaderCurrentBlockid(&reader);
interiorReaderDestroy(&reader);
rc = sql_get_statement(v, BLOCK_SELECT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 1, iBlockid);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, BLOCK_SELECT_STMT, &s);
if( rc==SQLITE_DONE ) return SQLITE_ERROR;
if( rc!=SQLITE_ROW ) return rc;
pData = sqlite3_column_blob(s, 0);
nData = sqlite3_column_bytes(s, 0);
}
rc = loadSegmentLeaf(v, pData, nData, pTerm, nTerm, out);
if( rc!=SQLITE_OK ) return rc;
/* If we selected a child node, we need to finish that select. */
if( s!=NULL ){
/* 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_ROW ) return SQLITE_ERROR;
if( rc!=SQLITE_DONE ) return rc;
}
return SQLITE_OK;
}
/* Scan the database and merge together the posting lists for the term
** into *out.
*/
static int termSelect(fulltext_vtab *v, int iColumn,
const char *pTerm, int nTerm,
DocListType iType, DataBuffer *out){
DataBuffer doclist;
sqlite3_stmt *s;
int rc = sql_get_statement(v, SEGDIR_SELECT_ALL_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
dataBufferInit(&doclist, 0);
/* Traverse the segments from oldest to newest so that newer doclist
** elements for given docids overwrite older elements.
*/
while( (rc=sql_step_statement(v, SEGDIR_SELECT_ALL_STMT, &s))==SQLITE_ROW ){
rc = loadSegment(v, sqlite3_column_blob(s, 0), sqlite3_column_bytes(s, 0),
pTerm, nTerm, &doclist);
if( rc!=SQLITE_OK ) goto err;
}
if( rc==SQLITE_DONE ){
if( doclist.nData!=0 ){
/* TODO(shess) The old term_select_all() code applied the column
** restrict as we merged segments, leading to smaller buffers.
** This is probably worthwhile to bring back, once the new storage
** system is checked in.
*/
if( iColumn==v->nColumn) iColumn = -1;
docListTrim(DL_DEFAULT, doclist.pData, doclist.nData,
iColumn, iType, out);
}
rc = SQLITE_OK;
}
err:
dataBufferDestroy(&doclist);
return rc;
}
/****************************************************************/
/* Used to hold hashtable data for sorting. */
typedef struct TermData {
const char *pTerm;
int nTerm;
PLWriter *pWriter;
} TermData;
/* Orders TermData elements in strcmp fashion ( <0 for less-than, 0
** for equal, >0 for greater-than).
*/
static int termDataCmp(const void *av, const void *bv){
const TermData *a = (const TermData *)av;
const TermData *b = (const TermData *)bv;
int n = a->nTerm<b->nTerm ? a->nTerm : b->nTerm;
int c = memcmp(a->pTerm, b->pTerm, n);
if( c!=0 ) return c;
return a->nTerm-b->nTerm;
}
/* Order pTerms data by term, then write a new level 0 segment using
** LeafWriter.
*/
static int writeZeroSegment(fulltext_vtab *v, fts2Hash *pTerms){
fts2HashElem *e;
int idx, rc, i, n;
TermData *pData;
LeafWriter writer;
DataBuffer dl;
/* Determine the next index at level 0, merging as necessary. */
rc = segdirNextIndex(v, 0, &idx);
if( rc!=SQLITE_OK ) return rc;
n = fts2HashCount(pTerms);
pData = malloc(n*sizeof(TermData));
for(i = 0, e = fts2HashFirst(pTerms); e; i++, e = fts2HashNext(e)){
assert( i<n );
pData[i].pTerm = fts2HashKey(e);
pData[i].nTerm = fts2HashKeysize(e);
pData[i].pWriter = fts2HashData(e);
}
assert( i==n );
/* TODO(shess) Should we allow user-defined collation sequences,
** here? I think we only need that once we support prefix searches.
*/
if( n>1 ) qsort(pData, n, sizeof(*pData), termDataCmp);
/* TODO(shess) Refactor so that we can write directly to the segment
** DataBuffer, as happens for segment merges.
*/
leafWriterInit(0, idx, &writer);
dataBufferInit(&dl, 0);
for(i=0; i<n; i++){
DLWriter dlw;
dataBufferReset(&dl);
dlwInit(&dlw, DL_DEFAULT, &dl);
plwDlwAdd(pData[i].pWriter, &dlw);
rc = leafWriterStep(v, &writer,
pData[i].pTerm, pData[i].nTerm, dl.pData, dl.nData);
dlwDestroy(&dlw);
if( rc!=SQLITE_OK ) goto err;
}
dataBufferDestroy(&dl);
rc = leafWriterFinalize(v, &writer);
err:
free(pData);
leafWriterDestroy(&writer);
return rc;
}
/* 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 ) rc = writeZeroSegment(v, &terms);
/* clean up */
for(e=fts2HashFirst(&terms); e; e=fts2HashNext(e)){
plwDelete(fts2HashData(e));
}
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) */
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