/* A helper function for mergeBlock(), below. Merge the position lists * pointed to by m->in and pBlockReader. * If the merge matches, write [iDocid] to m->pOut; if m->pOut * has positions then write all matching positions as well. */ static void mergePosList(DocListMerge *m, sqlite_int64 iDocid, DocListReader *pBlockReader){ int block_pos = readPosition(pBlockReader); int in_pos = readPosition(&m->in); int match = 0; while( block_pos!=-1 || in_pos!=-1 ){ if( block_pos-m->iOffset==in_pos ){ if( !match ){ docListAddDocid(m->pOut, iDocid); match = 1; } if( m->pOut->iType >= DL_POSITIONS ){ docListAddPos(m->pOut, in_pos); } block_pos = readPosition(pBlockReader); in_pos = readPosition(&m->in); } else if( in_pos==-1 || (block_pos!=-1 && block_pos-m->iOffset<in_pos) ){ block_pos = readPosition(pBlockReader); } else { in_pos = readPosition(&m->in); } } if( m->pOut->iType >= DL_POSITIONS && match ){ docListAddEndPos(m->pOut); } }
/* Doclist multi-tool. Pass pUpdate==NULL to delete the indicated docid; * otherwise pUpdate, which must contain only the single docid [iDocid], is * inserted (if not present) or updated (if already present). */ static int docListUpdate(DocList *d, sqlite_int64 iDocid, DocList *pUpdate){ int modified = 0; DocListReader reader; char *p; if( pUpdate!=NULL ){ assert( d->iType==pUpdate->iType); assert( iDocid==firstDocid(pUpdate) ); } readerInit(&reader, d); while( !readerAtEnd(&reader) && peekDocid(&reader)<iDocid ){ skipDocument(&reader); } p = reader.p; /* Delete if there is a matching element. */ if( !readerAtEnd(&reader) && iDocid==peekDocid(&reader) ){ skipDocument(&reader); memmove(p, reader.p, docListEnd(d) - reader.p); d->nData -= (reader.p - p); modified = 1; } /* Insert if indicated. */ if( pUpdate!=NULL ){ int iDoclist = p-d->pData; docListAddEndPos(pUpdate); d->pData = realloc(d->pData, d->nData+pUpdate->nData); p = d->pData + iDoclist; memmove(p+pUpdate->nData, p, docListEnd(d) - p); memcpy(p, pUpdate->pData, pUpdate->nData); d->nData += pUpdate->nData; modified = 1; } return modified; }
/* Merge one block of an on-disk doclist into a DocListMerge. */ static void mergeBlock(DocListMerge *m, DocList *pBlock){ DocListReader blockReader; assert( pBlock->iType >= DL_POSITIONS ); readerInit(&blockReader, pBlock); while( !readerAtEnd(&blockReader) ){ sqlite_int64 iDocid = readDocid(&blockReader); if( m->in.pDoclist!=NULL ){ while( 1 ){ if( readerAtEnd(&m->in) ) return; /* nothing more to merge */ if( peekDocid(&m->in)>=iDocid ) break; skipDocument(&m->in); } if( peekDocid(&m->in)>iDocid ){ /* [pIn] has no match with iDocid */ skipPositionList(&blockReader); /* skip this docid in the block */ continue; } readDocid(&m->in); } /* We have a document match. */ if( m->in.pDoclist==NULL || m->in.pDoclist->iType < DL_POSITIONS ){ /* We don't need to do a poslist merge. */ docListAddDocid(m->pOut, iDocid); if( m->pOut->iType >= DL_POSITIONS ){ /* Copy all positions to the output doclist. */ while( 1 ){ int pos = readPosition(&blockReader); if( pos==-1 ) break; docListAddPos(m->pOut, pos); } docListAddEndPos(m->pOut); } else skipPositionList(&blockReader); continue; } mergePosList(m, iDocid, &blockReader); } }
static void mergeBlock(DocListMerge *m, DocList *pBlock){ DocListReader blockReader; assert( pBlock->iType >= DL_POSITIONS ); readerInit(&blockReader, pBlock); while( !readerAtEnd(&blockReader) ){ sqlite_int64 iDocid = readDocid(&blockReader); if( m->in.pDoclist!=NULL ){ while( 1 ){ if( readerAtEnd(&m->in) ) return; if( peekDocid(&m->in)>=iDocid ) break; skipDocument(&m->in); } if( peekDocid(&m->in)>iDocid ){ skipPositionList(&blockReader); continue; } readDocid(&m->in); } if( m->in.pDoclist==NULL || m->in.pDoclist->iType < DL_POSITIONS ){ docListAddDocid(m->pOut, iDocid); if( m->pOut->iType >= DL_POSITIONS ){ while( 1 ){ int pos = readPosition(&blockReader); if( pos==-1 ) break; docListAddPos(m->pOut, pos); } docListAddEndPos(m->pOut); } else skipPositionList(&blockReader); continue; } mergePosList(m, iDocid, &blockReader); } }