diff options
Diffstat (limited to 'ext/fts3/fts3_aux.c')
| -rw-r--r-- | ext/fts3/fts3_aux.c | 474 |
1 files changed, 474 insertions, 0 deletions
diff --git a/ext/fts3/fts3_aux.c b/ext/fts3/fts3_aux.c new file mode 100644 index 0000000..ada85d7 --- /dev/null +++ b/ext/fts3/fts3_aux.c @@ -0,0 +1,474 @@ +/* +** 2011 Jan 27 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +****************************************************************************** +** +*/ +#include "fts3Int.h" +#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) + +#include <string.h> +#include <assert.h> + +typedef struct Fts3auxTable Fts3auxTable; +typedef struct Fts3auxCursor Fts3auxCursor; + +struct Fts3auxTable { + sqlite3_vtab base; /* Base class used by SQLite core */ + Fts3Table *pFts3Tab; +}; + +struct Fts3auxCursor { + sqlite3_vtab_cursor base; /* Base class used by SQLite core */ + Fts3MultiSegReader csr; /* Must be right after "base" */ + Fts3SegFilter filter; + char *zStop; + int nStop; /* Byte-length of string zStop */ + int isEof; /* True if cursor is at EOF */ + sqlite3_int64 iRowid; /* Current rowid */ + + int iCol; /* Current value of 'col' column */ + int nStat; /* Size of aStat[] array */ + struct Fts3auxColstats { + sqlite3_int64 nDoc; /* 'documents' values for current csr row */ + sqlite3_int64 nOcc; /* 'occurrences' values for current csr row */ + } *aStat; +}; + +/* +** Schema of the terms table. +*/ +#define FTS3_TERMS_SCHEMA "CREATE TABLE x(term, col, documents, occurrences)" + +/* +** This function does all the work for both the xConnect and xCreate methods. +** These tables have no persistent representation of their own, so xConnect +** and xCreate are identical operations. +*/ +static int fts3auxConnectMethod( + sqlite3 *db, /* Database connection */ + void *pUnused, /* Unused */ + int argc, /* Number of elements in argv array */ + const char * const *argv, /* xCreate/xConnect argument array */ + sqlite3_vtab **ppVtab, /* OUT: New sqlite3_vtab object */ + char **pzErr /* OUT: sqlite3_malloc'd error message */ +){ + char const *zDb; /* Name of database (e.g. "main") */ + char const *zFts3; /* Name of fts3 table */ + int nDb; /* Result of strlen(zDb) */ + int nFts3; /* Result of strlen(zFts3) */ + int nByte; /* Bytes of space to allocate here */ + int rc; /* value returned by declare_vtab() */ + Fts3auxTable *p; /* Virtual table object to return */ + + UNUSED_PARAMETER(pUnused); + + /* The user should specify a single argument - the name of an fts3 table. */ + if( argc!=4 ){ + *pzErr = sqlite3_mprintf( + "wrong number of arguments to fts4aux constructor" + ); + return SQLITE_ERROR; + } + + zDb = argv[1]; + nDb = strlen(zDb); + zFts3 = argv[3]; + nFts3 = strlen(zFts3); + + rc = sqlite3_declare_vtab(db, FTS3_TERMS_SCHEMA); + if( rc!=SQLITE_OK ) return rc; + + nByte = sizeof(Fts3auxTable) + sizeof(Fts3Table) + nDb + nFts3 + 2; + p = (Fts3auxTable *)sqlite3_malloc(nByte); + if( !p ) return SQLITE_NOMEM; + memset(p, 0, nByte); + + p->pFts3Tab = (Fts3Table *)&p[1]; + p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1]; + p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1]; + p->pFts3Tab->db = db; + p->pFts3Tab->nIndex = 1; + + memcpy((char *)p->pFts3Tab->zDb, zDb, nDb); + memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3); + sqlite3Fts3Dequote((char *)p->pFts3Tab->zName); + + *ppVtab = (sqlite3_vtab *)p; + return SQLITE_OK; +} + +/* +** This function does the work for both the xDisconnect and xDestroy methods. +** These tables have no persistent representation of their own, so xDisconnect +** and xDestroy are identical operations. +*/ +static int fts3auxDisconnectMethod(sqlite3_vtab *pVtab){ + Fts3auxTable *p = (Fts3auxTable *)pVtab; + Fts3Table *pFts3 = p->pFts3Tab; + int i; + + /* Free any prepared statements held */ + for(i=0; i<SizeofArray(pFts3->aStmt); i++){ + sqlite3_finalize(pFts3->aStmt[i]); + } + sqlite3_free(pFts3->zSegmentsTbl); + sqlite3_free(p); + return SQLITE_OK; +} + +#define FTS4AUX_EQ_CONSTRAINT 1 +#define FTS4AUX_GE_CONSTRAINT 2 +#define FTS4AUX_LE_CONSTRAINT 4 + +/* +** xBestIndex - Analyze a WHERE and ORDER BY clause. +*/ +static int fts3auxBestIndexMethod( + sqlite3_vtab *pVTab, + sqlite3_index_info *pInfo +){ + int i; + int iEq = -1; + int iGe = -1; + int iLe = -1; + + UNUSED_PARAMETER(pVTab); + + /* This vtab delivers always results in "ORDER BY term ASC" order. */ + if( pInfo->nOrderBy==1 + && pInfo->aOrderBy[0].iColumn==0 + && pInfo->aOrderBy[0].desc==0 + ){ + pInfo->orderByConsumed = 1; + } + + /* Search for equality and range constraints on the "term" column. */ + for(i=0; i<pInfo->nConstraint; i++){ + if( pInfo->aConstraint[i].usable && pInfo->aConstraint[i].iColumn==0 ){ + int op = pInfo->aConstraint[i].op; + if( op==SQLITE_INDEX_CONSTRAINT_EQ ) iEq = i; + if( op==SQLITE_INDEX_CONSTRAINT_LT ) iLe = i; + if( op==SQLITE_INDEX_CONSTRAINT_LE ) iLe = i; + if( op==SQLITE_INDEX_CONSTRAINT_GT ) iGe = i; + if( op==SQLITE_INDEX_CONSTRAINT_GE ) iGe = i; + } + } + + if( iEq>=0 ){ + pInfo->idxNum = FTS4AUX_EQ_CONSTRAINT; + pInfo->aConstraintUsage[iEq].argvIndex = 1; + pInfo->estimatedCost = 5; + }else{ + pInfo->idxNum = 0; + pInfo->estimatedCost = 20000; + if( iGe>=0 ){ + pInfo->idxNum += FTS4AUX_GE_CONSTRAINT; + pInfo->aConstraintUsage[iGe].argvIndex = 1; + pInfo->estimatedCost /= 2; + } + if( iLe>=0 ){ + pInfo->idxNum += FTS4AUX_LE_CONSTRAINT; + pInfo->aConstraintUsage[iLe].argvIndex = 1 + (iGe>=0); + pInfo->estimatedCost /= 2; + } + } + + return SQLITE_OK; +} + +/* +** xOpen - Open a cursor. +*/ +static int fts3auxOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){ + Fts3auxCursor *pCsr; /* Pointer to cursor object to return */ + + UNUSED_PARAMETER(pVTab); + + pCsr = (Fts3auxCursor *)sqlite3_malloc(sizeof(Fts3auxCursor)); + if( !pCsr ) return SQLITE_NOMEM; + memset(pCsr, 0, sizeof(Fts3auxCursor)); + + *ppCsr = (sqlite3_vtab_cursor *)pCsr; + return SQLITE_OK; +} + +/* +** xClose - Close a cursor. +*/ +static int fts3auxCloseMethod(sqlite3_vtab_cursor *pCursor){ + Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab; + Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor; + + sqlite3Fts3SegmentsClose(pFts3); + sqlite3Fts3SegReaderFinish(&pCsr->csr); + sqlite3_free((void *)pCsr->filter.zTerm); + sqlite3_free(pCsr->zStop); + sqlite3_free(pCsr->aStat); + sqlite3_free(pCsr); + return SQLITE_OK; +} + +static int fts3auxGrowStatArray(Fts3auxCursor *pCsr, int nSize){ + if( nSize>pCsr->nStat ){ + struct Fts3auxColstats *aNew; + aNew = (struct Fts3auxColstats *)sqlite3_realloc(pCsr->aStat, + sizeof(struct Fts3auxColstats) * nSize + ); + if( aNew==0 ) return SQLITE_NOMEM; + memset(&aNew[pCsr->nStat], 0, + sizeof(struct Fts3auxColstats) * (nSize - pCsr->nStat) + ); + pCsr->aStat = aNew; + pCsr->nStat = nSize; + } + return SQLITE_OK; +} + +/* +** xNext - Advance the cursor to the next row, if any. +*/ +static int fts3auxNextMethod(sqlite3_vtab_cursor *pCursor){ + Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor; + Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab; + int rc; + + /* Increment our pretend rowid value. */ + pCsr->iRowid++; + + for(pCsr->iCol++; pCsr->iCol<pCsr->nStat; pCsr->iCol++){ + if( pCsr->aStat[pCsr->iCol].nDoc>0 ) return SQLITE_OK; + } + + rc = sqlite3Fts3SegReaderStep(pFts3, &pCsr->csr); + if( rc==SQLITE_ROW ){ + int i = 0; + int nDoclist = pCsr->csr.nDoclist; + char *aDoclist = pCsr->csr.aDoclist; + int iCol; + + int eState = 0; + + if( pCsr->zStop ){ + int n = (pCsr->nStop<pCsr->csr.nTerm) ? pCsr->nStop : pCsr->csr.nTerm; + int mc = memcmp(pCsr->zStop, pCsr->csr.zTerm, n); + if( mc<0 || (mc==0 && pCsr->csr.nTerm>pCsr->nStop) ){ + pCsr->isEof = 1; + return SQLITE_OK; + } + } + + if( fts3auxGrowStatArray(pCsr, 2) ) return SQLITE_NOMEM; + memset(pCsr->aStat, 0, sizeof(struct Fts3auxColstats) * pCsr->nStat); + iCol = 0; + + while( i<nDoclist ){ + sqlite3_int64 v = 0; + + i += sqlite3Fts3GetVarint(&aDoclist[i], &v); + switch( eState ){ + /* State 0. In this state the integer just read was a docid. */ + case 0: + pCsr->aStat[0].nDoc++; + eState = 1; + iCol = 0; + break; + + /* State 1. In this state we are expecting either a 1, indicating + ** that the following integer will be a column number, or the + ** start of a position list for column 0. + ** + ** The only difference between state 1 and state 2 is that if the + ** integer encountered in state 1 is not 0 or 1, then we need to + ** increment the column 0 "nDoc" count for this term. + */ + case 1: + assert( iCol==0 ); + if( v>1 ){ + pCsr->aStat[1].nDoc++; + } + eState = 2; + /* fall through */ + + case 2: + if( v==0 ){ /* 0x00. Next integer will be a docid. */ + eState = 0; + }else if( v==1 ){ /* 0x01. Next integer will be a column number. */ + eState = 3; + }else{ /* 2 or greater. A position. */ + pCsr->aStat[iCol+1].nOcc++; + pCsr->aStat[0].nOcc++; + } + break; + + /* State 3. The integer just read is a column number. */ + default: assert( eState==3 ); + iCol = (int)v; + if( fts3auxGrowStatArray(pCsr, iCol+2) ) return SQLITE_NOMEM; + pCsr->aStat[iCol+1].nDoc++; + eState = 2; + break; + } + } + + pCsr->iCol = 0; + rc = SQLITE_OK; + }else{ + pCsr->isEof = 1; + } + return rc; +} + +/* +** xFilter - Initialize a cursor to point at the start of its data. +*/ +static int fts3auxFilterMethod( + sqlite3_vtab_cursor *pCursor, /* The cursor used for this query */ + int idxNum, /* Strategy index */ + const char *idxStr, /* Unused */ + int nVal, /* Number of elements in apVal */ + sqlite3_value **apVal /* Arguments for the indexing scheme */ +){ + Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor; + Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab; + int rc; + int isScan; + + UNUSED_PARAMETER(nVal); + UNUSED_PARAMETER(idxStr); + + assert( idxStr==0 ); + assert( idxNum==FTS4AUX_EQ_CONSTRAINT || idxNum==0 + || idxNum==FTS4AUX_LE_CONSTRAINT || idxNum==FTS4AUX_GE_CONSTRAINT + || idxNum==(FTS4AUX_LE_CONSTRAINT|FTS4AUX_GE_CONSTRAINT) + ); + isScan = (idxNum!=FTS4AUX_EQ_CONSTRAINT); + + /* In case this cursor is being reused, close and zero it. */ + testcase(pCsr->filter.zTerm); + sqlite3Fts3SegReaderFinish(&pCsr->csr); + sqlite3_free((void *)pCsr->filter.zTerm); + sqlite3_free(pCsr->aStat); + memset(&pCsr->csr, 0, ((u8*)&pCsr[1]) - (u8*)&pCsr->csr); + + pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY; + if( isScan ) pCsr->filter.flags |= FTS3_SEGMENT_SCAN; + + if( idxNum&(FTS4AUX_EQ_CONSTRAINT|FTS4AUX_GE_CONSTRAINT) ){ + const unsigned char *zStr = sqlite3_value_text(apVal[0]); + if( zStr ){ + pCsr->filter.zTerm = sqlite3_mprintf("%s", zStr); + pCsr->filter.nTerm = sqlite3_value_bytes(apVal[0]); + if( pCsr->filter.zTerm==0 ) return SQLITE_NOMEM; + } + } + if( idxNum&FTS4AUX_LE_CONSTRAINT ){ + int iIdx = (idxNum&FTS4AUX_GE_CONSTRAINT) ? 1 : 0; + pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iIdx])); + pCsr->nStop = sqlite3_value_bytes(apVal[iIdx]); + if( pCsr->zStop==0 ) return SQLITE_NOMEM; + } + + rc = sqlite3Fts3SegReaderCursor(pFts3, 0, FTS3_SEGCURSOR_ALL, + pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr + ); + if( rc==SQLITE_OK ){ + rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter); + } + + if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor); + return rc; +} + +/* +** xEof - Return true if the cursor is at EOF, or false otherwise. +*/ +static int fts3auxEofMethod(sqlite3_vtab_cursor *pCursor){ + Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor; + return pCsr->isEof; +} + +/* +** xColumn - Return a column value. +*/ +static int fts3auxColumnMethod( + sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */ + sqlite3_context *pContext, /* Context for sqlite3_result_xxx() calls */ + int iCol /* Index of column to read value from */ +){ + Fts3auxCursor *p = (Fts3auxCursor *)pCursor; + + assert( p->isEof==0 ); + if( iCol==0 ){ /* Column "term" */ + sqlite3_result_text(pContext, p->csr.zTerm, p->csr.nTerm, SQLITE_TRANSIENT); + }else if( iCol==1 ){ /* Column "col" */ + if( p->iCol ){ + sqlite3_result_int(pContext, p->iCol-1); + }else{ + sqlite3_result_text(pContext, "*", -1, SQLITE_STATIC); + } + }else if( iCol==2 ){ /* Column "documents" */ + sqlite3_result_int64(pContext, p->aStat[p->iCol].nDoc); + }else{ /* Column "occurrences" */ + sqlite3_result_int64(pContext, p->aStat[p->iCol].nOcc); + } + + return SQLITE_OK; +} + +/* +** xRowid - Return the current rowid for the cursor. +*/ +static int fts3auxRowidMethod( + sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */ + sqlite_int64 *pRowid /* OUT: Rowid value */ +){ + Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor; + *pRowid = pCsr->iRowid; + return SQLITE_OK; +} + +/* +** Register the fts3aux module with database connection db. Return SQLITE_OK +** if successful or an error code if sqlite3_create_module() fails. +*/ +int sqlite3Fts3InitAux(sqlite3 *db){ + static const sqlite3_module fts3aux_module = { + 0, /* iVersion */ + fts3auxConnectMethod, /* xCreate */ + fts3auxConnectMethod, /* xConnect */ + fts3auxBestIndexMethod, /* xBestIndex */ + fts3auxDisconnectMethod, /* xDisconnect */ + fts3auxDisconnectMethod, /* xDestroy */ + fts3auxOpenMethod, /* xOpen */ + fts3auxCloseMethod, /* xClose */ + fts3auxFilterMethod, /* xFilter */ + fts3auxNextMethod, /* xNext */ + fts3auxEofMethod, /* xEof */ + fts3auxColumnMethod, /* xColumn */ + fts3auxRowidMethod, /* xRowid */ + 0, /* xUpdate */ + 0, /* xBegin */ + 0, /* xSync */ + 0, /* xCommit */ + 0, /* xRollback */ + 0, /* xFindFunction */ + 0, /* xRename */ + 0, /* xSavepoint */ + 0, /* xRelease */ + 0 /* xRollbackTo */ + }; + int rc; /* Return code */ + + rc = sqlite3_create_module(db, "fts4aux", &fts3aux_module, 0); + return rc; +} + +#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */ |