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Add a couple of comments to fts3_snippet.c.

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FossilOrigin-Name: ad8df6c5ee0055cf1161a3b700d69dbe07d969bc
This commit is contained in:
dan 2010-11-26 15:13:31 +00:00
parent a93ca34129
commit 72de061fb1
3 changed files with 75 additions and 29 deletions
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90
ext/fts3/fts3_snippet.c
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@ -982,6 +982,12 @@ static int fts3MatchinfoSelectDoctotal(
return SQLITE_OK;
}
/*
** An instance of the following structure is used to store state while
** iterating through a multi-column position-list corresponding to the
** hits for a single phrase on a single row in order to calculate the
** values for a matchinfo() FTS3_MATCHINFO_LCS request.
*/
typedef struct LcsIterator LcsIterator;
struct LcsIterator {
Fts3Expr *pExpr; /* Pointer to phrase expression */
@ -991,6 +997,10 @@ struct LcsIterator {
int iPos; /* Current position */
};
/*
** If LcsIterator.iCol is set to the following value, the iterator has
** finished iterating through all offsets for all columns.
*/
#define LCS_ITERATOR_FINISHED 0x7FFFFFFF;
static int fts3MatchinfoLcsCb(
@ -1003,6 +1013,11 @@ static int fts3MatchinfoLcsCb(
return SQLITE_OK;
}
/*
** Advance the iterator passed as an argument to the next position. Return
** 1 if the iterator is at EOF or if it now points to the start of the
** position list for the next column.
*/
static int fts3LcsIteratorAdvance(LcsIterator *pIter){
char *pRead = pIter->pRead;
sqlite3_int64 iRead;
@ -1027,6 +1042,17 @@ static int fts3LcsIteratorAdvance(LcsIterator *pIter){
return rc;
}
/*
** This function implements the FTS3_MATCHINFO_LCS matchinfo() flag.
**
** If the call is successful, the longest-common-substring lengths for each
** column are written into the first nCol elements of the pInfo->aMatchinfo[]
** array before returning. SQLITE_OK is returned in this case.
**
** Otherwise, if an error occurs, an SQLite error code is returned and the
** data written to the first nCol elements of pInfo->aMatchinfo[] is
** undefined.
*/
static int fts3MatchinfoLcs(Fts3Cursor *pCsr, MatchInfo *pInfo){
LcsIterator *aIter;
int i;
@ -1040,7 +1066,6 @@ static int fts3MatchinfoLcs(Fts3Cursor *pCsr, MatchInfo *pInfo){
if( !aIter ) return SQLITE_NOMEM;
memset(aIter, 0, sizeof(LcsIterator) * pCsr->nPhrase);
(void)fts3ExprIterate(pCsr->pExpr, fts3MatchinfoLcsCb, (void*)aIter);
for(i=0; i<pInfo->nPhrase; i++){
LcsIterator *pIter = &aIter[i];
nToken -= pIter->pExpr->pPhrase->nToken;
@ -1055,37 +1080,41 @@ static int fts3MatchinfoLcs(Fts3Cursor *pCsr, MatchInfo *pInfo){
}
for(iCol=0; iCol<pInfo->nCol; iCol++){
int nLcs = 0;
int nLive = 0;
int nLcs = 0; /* LCS value for this column */
int nLive = 0; /* Number of iterators in aIter not at EOF */
/* Loop through the iterators in aIter[]. Set nLive to the number of
** iterators that point to a position-list corresponding to column iCol.
*/
for(i=0; i<pInfo->nPhrase; i++){
assert( aIter[i].iCol>=iCol );
if( aIter[i].iCol==iCol ) nLive++;
}
/* The following loop runs until all iterators in aIter[] have finished
** iterating through positions in column iCol. Exactly one of the
** iterators is advanced each time the body of the loop is run.
*/
while( nLive>0 ){
LcsIterator *pAdv = 0;
int nThisLcs = 0;
LcsIterator *pAdv = 0; /* The iterator to advance by one position */
int nThisLcs = 0; /* LCS for the current iterator positions */
for(i=0; i<pInfo->nPhrase; i++){
LcsIterator *pIter = &aIter[i];
if( iCol!=pIter->iCol ){
/* This iterator is already at EOF for this column. */
nThisLcs = 0;
continue;
}
if( pAdv==0 || pIter->iPos<pAdv->iPos ){
pAdv = pIter;
}
if( nThisLcs==0 || pIter->iPos==pIter[-1].iPos ){
nThisLcs++;
}else{
nThisLcs = 1;
if( pAdv==0 || pIter->iPos<pAdv->iPos ){
pAdv = pIter;
}
if( nThisLcs==0 || pIter->iPos==pIter[-1].iPos ){
nThisLcs++;
}else{
nThisLcs = 1;
}
if( nThisLcs>nLcs ) nLcs = nThisLcs;
}
if( nThisLcs>nLcs ) nLcs = nThisLcs;
}
if( fts3LcsIteratorAdvance(pAdv) ) nLive--;
}
@ -1097,6 +1126,23 @@ static int fts3MatchinfoLcs(Fts3Cursor *pCsr, MatchInfo *pInfo){
return SQLITE_OK;
}
/*
** Populate the buffer pInfo->aMatchinfo[] with an array of integers to
** be returned by the matchinfo() function. Argument zArg contains the
** format string passed as the second argument to matchinfo (or the
** default value "pcx" if no second argument was specified). The format
** string has already been validated and the pInfo->aMatchinfo[] array
** is guaranteed to be large enough for the output.
**
** If bGlobal is true, then populate all fields of the matchinfo() output.
** If it is false, then assume that those fields that do not change between
** rows (i.e. FTS3_MATCHINFO_NPHRASE, NCOL, NDOC, AVGLENGTH and part of HITS)
** have already been populated.
**
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs. If a value other than SQLITE_OK is returned, the state the
** pInfo->aMatchinfo[] buffer is left in is undefined.
*/
static int fts3MatchinfoValues(
Fts3Cursor *pCsr, /* FTS3 cursor object */
int bGlobal, /* True to grab the global stats */
@ -1106,17 +1152,16 @@ static int fts3MatchinfoValues(
int rc = SQLITE_OK;
int i;
Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
sqlite3_stmt *pSelect = 0;
for(i=0; rc==SQLITE_OK && zArg[i]; i++){
switch( zArg[i] ){
case FTS3_MATCHINFO_NPHRASE:
case FTS3_MATCHINFO_NPHRASE:
if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nPhrase;
break;
case FTS3_MATCHINFO_NCOL:
case FTS3_MATCHINFO_NCOL:
if( bGlobal ) pInfo->aMatchinfo[0] = pInfo->nCol;
break;
@ -1231,10 +1276,11 @@ static int fts3GetMatchinfo(
int nArg; /* Bytes in zArg */
int i; /* Used to iterate through zArg */
/* Load doclists for each phrase in the query. */
/* Determine the number of phrases in the query */
pCsr->nPhrase = fts3ExprPhraseCount(pCsr->pExpr);
sInfo.nPhrase = pCsr->nPhrase;
/* Determine the number of integers in the buffer returned by this call. */
for(i=0; zArg[i]; i++){
nMatchinfo += fts3MatchinfoSize(&sInfo, zArg[i]);
}

12
manifest
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@ -1,5 +1,5 @@
C Merge\swith\slatest\strunk\schanges.
D 2010-11-26T10:58:49
C Add\sa\scouple\sof\scomments\sto\sfts3_snippet.c.
D 2010-11-26T15:13:32
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in 4547616ad2286053af6ccccefa242dc925e49bf0
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -69,7 +69,7 @@ F ext/fts3/fts3_hash.c 3c8f6387a4a7f5305588b203fa7c887d753e1f1c
F ext/fts3/fts3_hash.h 8331fb2206c609f9fc4c4735b9ab5ad6137c88ec
F ext/fts3/fts3_icu.c ac494aed69835008185299315403044664bda295
F ext/fts3/fts3_porter.c 8df6f6efcc4e9e31f8bf73a4007c2e9abca1dfba
F ext/fts3/fts3_snippet.c 8dc1fe915ce572a2104c6399622d5d25d1acc4a4
F ext/fts3/fts3_snippet.c e8a952d5de28950c91bbfed3d75b77ae2c3977ce
F ext/fts3/fts3_tokenizer.c 1301b0ee3ef414caae3257a702215925cc48cd9c
F ext/fts3/fts3_tokenizer.h 13ffd9fcb397fec32a05ef5cd9e0fa659bf3dbd3
F ext/fts3/fts3_tokenizer1.c 6e5cbaa588924ac578263a598e4fb9f5c9bb179d
@ -889,7 +889,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
P 70495ceccc793d608930f59e330777f287ba1ede 461f1a010f55e7da6b43ea65550066b1ca7abad0
R 3b6d9b4a663b0a1515af15682274f8ae
P 515cb3f4e5282551d300ba79c8885b8ca016a408
R 2c5f31c8d333c565e4e278772ba9f1b5
U dan
Z dc2d0a6a7b958d42d4d80a0f05fc0556
Z cd104d5839634fc3855fe1622f7c9862

2
manifest.uuid
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@ -1 +1 @@
515cb3f4e5282551d300ba79c8885b8ca016a408
ad8df6c5ee0055cf1161a3b700d69dbe07d969bc