/*
** Advance iterator pIter to the next entry.
**
** If an error occurs, Fts5Index.rc is set to an appropriate error code. It
** is not considered an error if the iterator reaches EOF. If an error has
** already occurred when this function is called, it is a no-op.
*/


/*
** Iterator pIter currently points to the first rowid of a doclist.
** There is a doclist-index associated with the final term on the current
** page. If the current term is the last term on the page, load the
** doclist-index from disk and initialize an iterator at (pIter->pDlidx).
*/


/*
** The iterator object passed as the second argument currently contains
** no valid values except for the Fts5SegIter.pLeaf member variable. This
** function searches the leaf page for a term matching (pTerm/nTerm).
**
** If the specified term is found on the page, then the iterator is left
** pointing to it. If argument bGe is zero and the term is not found,
** the iterator is left pointing at EOF.
**
** If bGe is non-zero and the specified term is not found, then the
** iterator is left pointing to the smallest term in the segment that
** is larger than the specified term, even if this term is not on the
** current page.
*/


/*
** Initialize the object pIter to point to term pTerm/nTerm within segment
** pSeg. If there is no such term in the index, the iterator is set to EOF.
**
** If an error occurs, Fts5Index.rc is set to an appropriate error code. If
** an error has already occurred when this function is called, it is a no-op.
*/


/*
** Initialize the object pIter to point to term pTerm/nTerm within the
** in-memory hash table. If there is no such term in the hash-table, the
** iterator is set to EOF.
**
** If an error occurs, Fts5Index.rc is set to an appropriate error code. If
** an error has already occurred when this function is called, it is a no-op.
*/


/*
** Zero the iterator passed as the only argument.
*/


/*
** This function is used as part of the big assert() procedure implemented by
** fts5AssertMultiIterSetup(). It ensures that the result currently stored
** in *pRes is the correct result of comparing the current positions of the
** two iterators.
*/


/*
** This function is a no-op unless SQLITE_DEBUG is defined when this module
** is compiled. In that case, this function is essentially an assert()
** statement used to verify that the contents of the pIter->aFirst[] array
** are correct.
*/


/*
** Do the comparison necessary to populate pIter->aFirst[iOut].
**
** If the returned value is non-zero, then it is the index of an entry
** in the pIter->aSeg[] array that is (a) not at EOF, and (b) pointing
** to a key that is a duplicate of another, higher priority,
** segment-iterator in the pSeg->aSeg[] array.
*/


/*
** Move the seg-iter so that it points to the first rowid on page iLeafPgno.
** It is an error if leaf iLeafPgno does not exist or contains no rowids.
*/


/*
** Advance the iterator passed as the second argument until it is at or
** past rowid iFrom. Regardless of the value of iFrom, the iterator is
** always advanced at least once.
*/


/*
** Free the iterator object passed as the second argument.
*/


/*
** Sub-iterator iChanged of iterator pIter has just been advanced. It still
** points to the same term though - just a different rowid. This function
** attempts to update the contents of the pIter->aFirst[] accordingly.
** If it does so successfully, 0 is returned. Otherwise 1.
**
** If non-zero is returned, the caller should call fts5MultiIterAdvanced()
** on the iterator instead. That function does the same as this one, except
** that it deals with more complicated cases as well.
*/


/*
** Set the pIter->bEof variable based on the state of the sub-iterators.
*/


/*
** Move the iterator to the next entry.
**
** If an error occurs, an error code is left in Fts5Index.rc. It is not
** considered an error if the iterator reaches EOF, or if it is already at
** EOF when this function is called.
*/


/*
** Iterator pIter currently points to a valid entry (not EOF). This
** function appends the position list data for the current entry to
** buffer pBuf. It does not make a copy of the position-list size
** field.
*/


/*
** Parameter pPos points to a buffer containing a position list, size nPos.
** This function filters it according to pColset (which must be non-NULL)
** and sets pIter->base.pData/nData to point to the new position list.
** If memory is required for the new position list, use buffer pIter->poslist.
** Or, if the new position list is a contiguous subset of the input, set
** pIter->base.pData/nData to point directly to it.
**
** This function is a no-op if *pRc is other than SQLITE_OK when it is
** called. If an OOM error is encountered, *pRc is set to SQLITE_NOMEM
** before returning.
*/


/*
** xSetOutputs callback used by detail=none tables.
*/


/*
** xSetOutputs callback used by detail=full and detail=col tables when no
** column filters are specified.
*/


/*
** xSetOutputs callback used by detail=col when there is a column filter
** and there are 100 or more columns. Also called as a fallback from
** fts5IterSetOutputs_Col100 if the column-list spans more than one page.
*/


/*
** xSetOutputs callback used when:
**
**   * detail=col,
**   * there is a column filter, and
**   * the table contains 100 or fewer columns.
**
** The last point is to ensure all column numbers are stored as
** single-byte varints.
*/


/*
** xSetOutputs callback used by detail=full when there is a column filter.
*/


/*
** Allocate a new Fts5Iter object.
**
** The new object will be used to iterate through data in structure pStruct.
** If iLevel is -ve, then all data in all segments is merged. Or, if iLevel
** is zero or greater, data from the first nSegment segments on level iLevel
** is merged.
**
** The iterator initially points to the first term/rowid entry in the
** iterated data.
*/


/*
** Create an Fts5Iter that iterates through the doclist provided
** as the second argument.
*/


/*
** Return true if the iterator is at EOF or if an error has occurred.
** False otherwise.
*/


/*
** Move the iterator to the next entry at or following iMatch.
*/


/*
** Return a pointer to a buffer containing the term associated with the
** entry that the iterator currently points to.
*/


/*
** Allocate a new segment-id for the structure pStruct. The new segment
** id must be between 1 and 65335 inclusive, and must not be used by
** any currently existing segment. If a free segment id cannot be found,
** SQLITE_FULL is returned.
**
** If an error has already occurred, this function is a no-op. 0 is
** returned in this case.
*/


/*
** Discard all data currently cached in the hash-tables.
*/


/*
** Return the size of the prefix, in bytes, that buffer
** (pNew/<length-unknown>) shares with buffer (pOld/nOld).
**
** Buffer (pNew/<length-unknown>) is guaranteed to be greater
** than buffer (pOld/nOld).
*/


/*
** Grow the pWriter->aDlidx[] array to at least nLvl elements in size.
** Any new array elements are zeroed before returning.
*/


/*
** If the current doclist-index accumulating in pWriter->aDlidx[] is large
** enough, flush it to disk and return 1. Otherwise discard it and return
** zero.
*/


/*
** This function is called whenever processing of the doclist for the
** last term on leaf page (pWriter->iBtPage) is completed.
**
** The doclist-index for that term is currently stored in-memory within the
** Fts5SegWriter.aDlidx[] array. If it is large enough, this function
** writes it out to disk. Or, if it is too small to bother with, discards
** it.
**
** Fts5SegWriter.btterm currently contains the first term on page iBtPage.
*/


/*
** This is called once for each leaf page except the first that contains
** at least one term. Argument (nTerm/pTerm) is the split-key - a term that
** is larger than all terms written to earlier leaves, and equal to or
** smaller than the first term on the new leaf.
**
** If an error occurs, an error code is left in Fts5Index.rc. If an error
** has already occurred when this function is called, it is a no-op.
*/


/*
** This function is called when flushing a leaf page that contains no
** terms at all to disk.
*/


/*
** Rowid iRowid has just been appended to the current leaf page. It is the
** first on the page. This function appends an appropriate entry to the current
** doclist-index.
*/


/*
** Append term pTerm/nTerm to the segment being written by the writer passed
** as the second argument.
**
** If an error occurs, set the Fts5Index.rc error code. If an error has
** already occurred, this function is a no-op.
*/


/*
** Append a rowid and position-list size field to the writers output.
*/


/*
** Flush any data cached by the writer object to the database. Free any
** allocations associated with the writer.
*/


/*
** Iterator pIter was used to iterate through the input segments of on an
** incremental merge operation. This function is called if the incremental
** merge step has finished but the input has not been completely exhausted.
*/


/*
** Do up to nPg pages of automerge work on the index.
**
** Return true if any changes were actually made, or false otherwise.
*/


/*
** A total of nLeaf leaf pages of data has just been flushed to a level-0
** segment. This function updates the write-counter accordingly and, if
** necessary, performs incremental merge work.
**
** If an error occurs, set the Fts5Index.rc error code. If an error has
** already occurred, this function is a no-op.
*/


/*
** Buffer aBuf[] contains a list of varints, all small enough to fit
** in a 32-bit integer. Return the size of the largest prefix of this
** list nMax bytes or less in size.
*/


/*
** Flush the contents of in-memory hash table iHash to a new level-0
** segment on disk. Also update the corresponding structure record.
**
** If an error occurs, set the Fts5Index.rc error code. If an error has
** already occurred, this function is a no-op.
*/


/*
** Flush any data stored in the in-memory hash tables to the database.
*/


/*
** This is called to implement the special "VALUES('merge', $nMerge)"
** INSERT command.
*/


/*
** Append a doclist to buffer pBuf.
**
** This function assumes that space within the buffer has already been
** allocated.
*/


/*
** Swap the contents of buffer *p1 with that of *p2.
*/


/*
** This is the equivalent of fts5MergePrefixLists() for detail=none mode.
** In this case the buffers consist of a delta-encoded list of rowids only.
*/


/*
** Array aBuf[] contains nBuf doclists. These are all merged in with the
** doclist in buffer p1.
*/


/*
** Indicate that all subsequent calls to sqlite3Fts5IndexWrite() pertain
** to the document with rowid iRowid.
*/


/*
** Commit data to disk.
*/


/*
** Discard any data stored in the in-memory hash tables. Do not write it
** to the database. Additionally, assume that the contents of the %_data
** table may have changed on disk. So any in-memory caches of %_data
** records must be invalidated.
*/


/*
** The %_data table is completely empty when this function is called. This
** function populates it with the initial structure objects for each index,
** and the initial version of the "averages" record (a zero-byte blob).
*/


/*
** Open a new Fts5Index handle. If the bCreate argument is true, create
** and initialize the underlying %_data table.
**
** If successful, set *pp to point to the new object and return SQLITE_OK.
** Otherwise, set *pp to NULL and return an SQLite error code.
*/


/*
** Close a handle opened by an earlier call to sqlite3Fts5IndexOpen().
*/


/*
** Argument p points to a buffer containing utf-8 text that is n bytes in
** size. Return the number of bytes in the nChar character prefix of the
** buffer, or 0 if there are less than nChar characters in total.
*/


/*
** pIn is a UTF-8 encoded string, nIn bytes in size. Return the number of
** unicode characters in the string.
*/


/*
** Insert or remove data to or from the index. Each time a document is
** added to or removed from the index, this function is called one or more
** times.
**
** For an insert, it must be called once for each token in the new document.
** If the operation is a delete, it must be called (at least) once for each
** unique token in the document with an iCol value less than zero. The iPos
** argument is ignored for a delete.
*/


/*
** Move to the next matching rowid.
*/


/*
** Move to the next matching term/rowid. Used by the fts5vocab module.
*/


/*
** Move to the next matching rowid that occurs at or after iMatch. The
** definition of "at or after" depends on whether this iterator iterates
** in ascending or descending rowid order.
*/


/*
** Return the current term.
*/


/*
** Close an iterator opened by an earlier call to sqlite3Fts5IndexQuery().
*/


/*
** Read and decode the "averages" record from the database.
**
** Parameter anSize must point to an array of size nCol, where nCol is
** the number of user defined columns in the FTS table.
*/


/*
** Replace the current "averages" record with the contents of the buffer
** supplied as the second argument.
*/


/*
** Set the 32-bit cookie value stored at the start of all structure
** records to the value passed as the second argument.
**
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs.
*/


/*
** Return a simple checksum value based on the arguments.
*/


/*
** This function is purely an internal test. It does not contribute to
** FTS functionality, or even the integrity-check, in any way.
**
** Instead, it tests that the same set of pgno/rowid combinations are
** visited regardless of whether the doclist-index identified by parameters
** iSegid/iLeaf is iterated in forwards or reverse order.
*/


/*
** Check if buffer z[], size n bytes, contains as series of valid utf-8
** encoded codepoints. If so, return 0. Otherwise, if the buffer does not
** contain valid utf-8, return non-zero.
*/


/*
** This function is also purely an internal test. It does not contribute to
** FTS functionality, or even the integrity-check, in any way.
*/


/*
** Check that:
**
**   1) All leaves of pSeg between iFirst and iLast (inclusive) exist and
**      contain zero terms.
**   2) All leaves of pSeg between iNoRowid and iLast (inclusive) exist and
**      contain zero rowids.
*/


/*
** Run internal checks to ensure that the FTS index (a) is internally
** consistent and (b) contains entries for which the XOR of the checksums
** as calculated by sqlite3Fts5IndexEntryCksum() is cksum.
**
** Return SQLITE_CORRUPT if any of the internal checks fail, or if the
** checksum does not match. Return SQLITE_OK if all checks pass without
** error, or some other SQLite error code if another error (e.g. OOM)
** occurs.
*/


/*
** Decode a segment-data rowid from the %_data table. This function is
** the opposite of macro FTS5_SEGMENT_ROWID().
*/


/*
** This is part of the fts5_decode() debugging aid.
**
** Arguments pBlob/nBlob contain a serialized Fts5Structure object. This
** function appends a human-readable representation of the same object
** to the buffer passed as the second argument.
*/


/*
** This is part of the fts5_decode() debugging aid.
**
** Arguments pBlob/nBlob contain an "averages" record. This function
** appends a human-readable representation of record to the buffer passed
** as the second argument.
*/


/*
** Buffer (a/n) is assumed to contain a list of serialized varints. Read
** each varint and append its string representation to buffer pBuf. Return
** after either the input buffer is exhausted or a 0 value is read.
**
** The return value is the number of bytes read from the input buffer.
*/


/*
** The start of buffer (a/n) contains the start of a doclist. The doclist
** may or may not finish within the buffer. This function appends a text
** representation of the part of the doclist that is present to buffer
** pBuf.
**
** The return value is the number of bytes read from the input buffer.
*/


/*
** This function is part of the fts5_decode() debugging function. It is
** only ever used with detail=none tables.
**
** Buffer (pData/nData) contains a doclist in the format used by detail=none
** tables. This function appends a human-readable version of that list to
** buffer pBuf.
**
** If *pRc is other than SQLITE_OK when this function is called, it is a
** no-op. If an OOM or other error occurs within this function, *pRc is
** set to an SQLite error code before returning. The final state of buffer
** pBuf is undefined in this case.
*/


/*
** The implementation of user-defined scalar function fts5_decode().
*/


/*
** The implementation of user-defined scalar function fts5_rowid().
*/


/*
** This is called as part of registering the FTS5 module with database
** connection db. It registers several user-defined scalar functions useful
** with FTS5.
**
** If successful, SQLITE_OK is returned. If an error occurs, some other
** SQLite error code is returned instead.
*/


/*
** Delete a virtual table handle allocated by fts5InitVtab().
*/


/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
**   argv[0]   -> module name  ("fts5")
**   argv[1]   -> database name
**   argv[2]   -> table name
**   argv[...] -> "column name" and other module argument fields.
*/


/*
** The xConnect() and xCreate() methods for the virtual table. All the
** work is done in function fts5InitVtab().
*/


/*
** Implementation of the xBestIndex method for FTS5 tables. Within the
** WHERE constraint, it searches for the following:
**
**   1. A MATCH constraint against the table column.
**   2. A MATCH constraint against the "rank" column.
**   3. A MATCH constraint against some other column.
**   4. An == constraint against the rowid column.
**   5. A < or <= constraint against the rowid column.
**   6. A > or >= constraint against the rowid column.
**
** Within the ORDER BY, the following are supported:
**
**   5. ORDER BY rank [ASC|DESC]
**   6. ORDER BY rowid [ASC|DESC]
**
** Information for the xFilter call is passed via both the idxNum and
** idxStr variables. Specifically, idxNum is a bitmask of the following
** flags used to encode the ORDER BY clause:
**
**     FTS5_BI_ORDER_RANK
**     FTS5_BI_ORDER_ROWID
**     FTS5_BI_ORDER_DESC
**
** idxStr is used to encode data from the WHERE clause. For each argument
** passed to the xFilter method, the following is appended to idxStr:
**
**   Match against table column:            "m"
**   Match against rank column:             "r"
**   Match against other column:            "M<column-number>"
**   LIKE  against other column:            "L<column-number>"
**   GLOB  against other column:            "G<column-number>"
**   Equality constraint against the rowid: "="
**   A < or <= against the rowid:           "<"
**   A > or >= against the rowid:           ">"
**
** This function ensures that there is at most one "r" or "=". And that if
** there exists an "=" then there is no "<" or ">".
**
** Costs are assigned as follows:
**
**  a) If an unusable MATCH operator is present in the WHERE clause, the
**     cost is unconditionally set to 1e50 (a really big number).
**
**  a) If a MATCH operator is present, the cost depends on the other
**     constraints also present. As follows:
**
**       * No other constraints:         cost=1000.0
**       * One rowid range constraint:   cost=750.0
**       * Both rowid range constraints: cost=500.0
**       * An == rowid constraint:       cost=100.0
**
**  b) Otherwise, if there is no MATCH:
**
**       * No other constraints:         cost=1000000.0
**       * One rowid range constraint:   cost=750000.0
**       * Both rowid range constraints: cost=250000.0
**       * An == rowid constraint:       cost=10.0
**
** Costs are not modified by the ORDER BY clause.
*/


/*
** This function is called after the cursor passed as the only argument
** is moved to point at a different row. It clears all cached data
** specific to the previous row stored by the cursor object.
*/


/*
** Set the FTS5CSR_REQUIRE_RESEEK flag on all FTS5_PLAN_MATCH cursors
** open on table pTab.
*/


/*
** If the REQUIRE_RESEEK flag is set on the cursor passed as the first
** argument, close and reopen all Fts5IndexIter iterators that the cursor
** is using. Then attempt to move the cursor to a rowid equal to or laster
** (in the cursors sort order - ASC or DESC) than the current rowid.
**
** If the new rowid is not equal to the old, set output parameter *pbSkip
** to 1 before returning. Otherwise, leave it unchanged.
**
** Return SQLITE_OK if successful or if no reseek was required, or an
** error code if an error occurred.
*/


/*
** Advance the cursor to the next row in the table that matches the
** search criteria.
**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts5EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/


/*
** Process a "special" query. A special query is identified as one with a
** MATCH expression that begins with a '*' character. The remainder of
** the text passed to the MATCH operator are used as  the special query
** parameters.
*/


/*
** Search for an auxiliary function named zName that can be used with table
** pTab. If one is found, return a pointer to the corresponding Fts5Auxiliary
** structure. Otherwise, if no such function exists, return NULL.
*/


/*
** This is the xFilter interface for the virtual table.  See
** the virtual table xFilter method documentation for additional
** information.
**
** There are three possible query strategies:
**
**   1. Full-text search using a MATCH operator.
**   2. A by-rowid lookup.
**   3. A full-table scan.
*/


/*
** Return the rowid that the cursor currently points to.
*/


/*
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts5
** exposes %_content.rowid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/


/*
** If the cursor requires seeking (bSeekRequired flag is set), seek it.
** Return SQLITE_OK if no error occurs, or an SQLite error code otherwise.
**
** If argument bErrormsg is true and an error occurs, an error message may
** be left in sqlite3_vtab.zErrMsg.
*/


/*
** This function is called to handle an FTS INSERT command. In other words,
** an INSERT statement of the form:
**
**     INSERT INTO fts(fts) VALUES($pCmd)
**     INSERT INTO fts(fts, rank) VALUES($pCmd, $pVal)
**
** Argument pVal is the value assigned to column "fts" by the INSERT
** statement. This function returns SQLITE_OK if successful, or an SQLite
** error code if an error occurs.
**
** The commands implemented by this function are documented in the "Special
** INSERT Directives" section of the documentation. It should be updated if
** more commands are added to this function.
*/


/*
** This function is the implementation of the xUpdate callback used by
** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
** inserted, updated or deleted.
**
** A delete specifies a single argument - the rowid of the row to remove.
**
** Update and insert operations pass:
**
**   1. The "old" rowid, or NULL.
**   2. The "new" rowid.
**   3. Values for each of the nCol matchable columns.
**   4. Values for the two hidden columns (<tablename> and "rank").
*/


/*
** Implementation of xSync() method.
*/


/*
** Implementation of xCommit() method. This is a no-op. The contents of
** the pending-terms hash-table have already been flushed into the database
** by fts5SyncMethod().
*/


/*
** Implementation of xRollback(). Discard the contents of the pending-terms
** hash-table. Any changes made to the database are reverted by SQLite.
*/


/*
** Ensure that the Fts5Cursor.nInstCount and aInst[] variables are populated
** correctly for the current view. Return SQLITE_OK if successful, or an
** SQLite error code otherwise.
*/


/*
** Implementation of the xSetAuxdata() method.
*/


/*
** Implementation of API function xQueryPhrase().
*/


/*
** Given cursor id iId, return a pointer to the corresponding Fts5Table
** object. Or NULL If the cursor id does not exist.
*/


/*
** Return a "position-list blob" corresponding to the current position of
** cursor pCsr via sqlite3_result_blob(). A position-list blob contains
** the current position-list for each phrase in the query associated with
** cursor pCsr.
**
** A position-list blob begins with (nPhrase-1) varints, where nPhrase is
** the number of phrases in the query. Following the varints are the
** concatenated position lists for each phrase, in order.
**
** The first varint (if it exists) contains the size of the position list
** for phrase 0. The second (same disclaimer) contains the size of position
** list 1. And so on. There is no size field for the final position list,
** as it can be derived from the total size of the blob.
*/


/*
** This is the xColumn method, called by SQLite to request a value from
** the row that the supplied cursor currently points to.
*/


/*
** Implementation of FTS5 xRename method. Rename an fts5 table.
*/


/*
** Register a new auxiliary function with global context pGlobal.
*/


/*
** Register a new tokenizer. This is the implementation of the
** fts5_api.xCreateTokenizer() method.
*/


/*
** Find a tokenizer. This is the implementation of the
** fts5_api.xFindTokenizer() method.
*/


/*
** Implementation of fts5_source_id() function.
*/


/*
** Prepare the two insert statements - Fts5Storage.pInsertContent and
** Fts5Storage.pInsertDocsize - if they have not already been prepared.
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs.
*/


/*
** Drop all shadow tables. Return SQLITE_OK if successful or an SQLite error
** code otherwise.
*/


/*
** Open a new Fts5Index handle. If the bCreate argument is true, create
** and initialize the underlying tables
**
** If successful, set *pp to point to the new object and return SQLITE_OK.
** Otherwise, set *pp to NULL and return an SQLite error code.
*/


/*
** Close a handle opened by an earlier call to sqlite3Fts5StorageOpen().
*/


/*
** Tokenization callback used when inserting tokens into the FTS index.
*/


/*
** If a row with rowid iDel is present in the %_content table, add the
** delete-markers to the FTS index necessary to delete it. Do not actually
** remove the %_content row at this time though.
*/


/*
** Insert a record into the %_docsize table. Specifically, do:
**
**   INSERT OR REPLACE INTO %_docsize(id, sz) VALUES(iRowid, pBuf);
**
** If there is no %_docsize table (as happens if the columnsize=0 option
** is specified when the FTS5 table is created), this function is a no-op.
*/


/*
** Load the contents of the "averages" record from disk into the
** p->nTotalRow and p->aTotalSize[] variables. If successful, and if
** argument bCache is true, set the p->bTotalsValid flag to indicate
** that the contents of aTotalSize[] and nTotalRow are valid until
** further notice.
**
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs.
*/


/*
** Store the current contents of the p->nTotalRow and p->aTotalSize[]
** variables in the "averages" record on disk.
**
** Return SQLITE_OK if successful, or an SQLite error code if an error
** occurs.
*/


/*
** Remove a row from the FTS table.
*/


/*
** Delete all entries in the FTS5 index.
*/


/*
** Allocate a new rowid. This is used for "external content" tables when
** a NULL value is inserted into the rowid column. The new rowid is allocated
** by inserting a dummy row into the %_docsize table. The dummy will be
** overwritten later.
**
** If the %_docsize table does not exist, SQLITE_MISMATCH is returned. In
** this case the user is required to provide a rowid explicitly.
*/


/*
** Insert a new row into the FTS content table.
*/


/*
** Insert new entries into the FTS index and %_docsize table.
*/


/*
** Tokenization callback used by integrity check.
*/


/*
** Check that the contents of the FTS index match that of the %_content
** table. Return SQLITE_OK if they do, or SQLITE_CORRUPT if not. Return
** some other SQLite error code if an error occurs while attempting to
** determine this.
*/


/*
** Obtain an SQLite statement handle that may be used to read data from the
** %_content table.
*/


/*
** Release an SQLite statement handle obtained via an earlier call to
** sqlite3Fts5StorageStmt(). The eStmt parameter passed to this function
** must match that passed to the sqlite3Fts5StorageStmt() call.
*/


/*
** Argument aCol points to an array of integers containing one entry for
** each table column. This function reads the %_docsize record for the
** specified rowid and populates aCol[] with the results.
**
** An SQLite error code is returned if an error occurs, or SQLITE_OK
** otherwise.
*/


/*
** Flush any data currently held in-memory to disk.
*/


/*
** Create an "ascii" tokenizer.
*/


/*
** Tokenize some text using the ascii tokenizer.
*/


/*
** Delete a "unicode61" tokenizer.
*/


/*
** Create a "unicode61" tokenizer.
*/


/*
** Return true if, for the purposes of tokenizing with the tokenizer
** passed as the first argument, codepoint iCode is considered a token
** character (not a separator).
*/


/*
** Delete a "porter" tokenizer.
*/


/*
** Create a "porter" tokenizer.
*/


/* porter rule condition: (m > 1) */


/* porter rule condition: (m = 1) */


/* porter rule condition: (*o) */


/* porter rule condition: (m > 1 and (*S or *T)) */


/* porter rule condition: (*v*) */


/**************************************************************************
***************************************************************************
** GENERATED CODE STARTS HERE (mkportersteps.tcl)
*/


/*
** GENERATED CODE ENDS HERE (mkportersteps.tcl)
***************************************************************************
**************************************************************************/


/*
** Tokenize using the porter tokenizer.
*/


/*
** Allocate a trigram tokenizer.
*/


/*
** Trigram tokenizer tokenize routine.
*/


/*
** Argument xCreate is a pointer to a constructor function for a tokenizer.
** pTok is a tokenizer previously created using the same method. This function
** returns one of FTS5_PATTERN_NONE, FTS5_PATTERN_LIKE or FTS5_PATTERN_GLOB
** indicating the style of pattern matching that the tokenizer can support.
** In practice, this is:
**
**     "trigram" tokenizer, case_sensitive=1 - FTS5_PATTERN_GLOB
**     "trigram" tokenizer, case_sensitive=0 (the default) - FTS5_PATTERN_LIKE
**     all other tokenizers - FTS5_PATTERN_NONE
*/


/*
** Register all built-in tokenizers with FTS5.
*/


/*
** Return true if the argument interpreted as a unicode codepoint
** is a diacritical modifier character.
*/


/*
** Interpret the argument as a unicode codepoint. If the codepoint
** is an upper case character that has a lower case equivalent,
** return the codepoint corresponding to the lower case version.
** Otherwise, return a copy of the argument.
**
** The results are undefined if the value passed to this function
** is less than zero.
*/


/*
** This is a copy of the sqlite3GetVarint32() routine from the SQLite core.
** Except, this version does handle the single byte case that the core
** version depends on being handled before its function is called.
*/


/*
** Read a 64-bit variable-length integer from memory starting at p[0].
** Return the number of bytes read.  The value is stored in *v.
*/


/*
** Translate a string containing an fts5vocab table type to an
** FTS5_VOCAB_XXX constant. If successful, set *peType to the output
** value and return SQLITE_OK. Otherwise, set *pzErr to an error message
** and return SQLITE_ERROR.
*/


/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
**   argv[0]   -> module name  ("fts5vocab")
**   argv[1]   -> database name
**   argv[2]   -> table name
**
** then:
**
**   argv[3]   -> name of fts5 table
**   argv[4]   -> type of fts5vocab table
**
** or, for tables in the TEMP schema only.
**
**   argv[3]   -> name of fts5 tables database
**   argv[4]   -> name of fts5 table
**   argv[5]   -> type of fts5vocab table
*/


/*
** The xConnect() and xCreate() methods for the virtual table. All the
** work is done in function fts5VocabInitVtab().
*/


/*
** Implementation of the xBestIndex method.
**
** Only constraints of the form:
**
**     term <= ?
**     term == ?
**     term >= ?
**
** are interpreted. Less-than and less-than-or-equal are treated
** identically, as are greater-than and greater-than-or-equal.
*/


/*
** Advance the cursor to the next row in the table.
*/


/*
** This is the xFilter implementation for the virtual table.
*/


/*
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. The
** rowid should be written to *pRowid.
*/


/*
** The stmtConnect() method is invoked to create a new
** stmt_vtab that describes the stmt virtual table.
**
** Think of this routine as the constructor for stmt_vtab objects.
**
** All this routine needs to do is:
**
**    (1) Allocate the stmt_vtab object and initialize all fields.
**
**    (2) Tell SQLite (via the sqlite3_declare_vtab() interface) what the
**        result set of queries against stmt will look like.
*/


/*
** Constructor for a new stmt_cursor object.
*/


/*
** Advance a stmt_cursor to its next row of output.
*/


/*
** Return values of columns for the row at which the stmt_cursor
** is currently pointing.
*/


/*
** This method is called to "rewind" the stmt_cursor object back
** to the first row of output.  This method is always called at least
** once prior to any call to stmtColumn() or stmtRowid() or
** stmtEof().
*/


/*
** SQLite will invoke this method one or more times while planning a query
** that uses the stmt virtual table.  This routine needs to create
** a query plan for each invocation and compute an estimated cost for that
** plan.
*/


// end of main file //


/*
** Change the size of an existing memory allocation.
**
** For this debugging implementation, we *always* make a copy of the
** allocation into a new place in memory.  In this way, if the
** higher level code is using pointer to the old allocation, it is
** much more likely to break and we are much more liking to find
** the error.
*/


/*
** Unlink the chunk at index i from
** whatever list is currently a member of.
*/


/*
** Chunk i is a free chunk that has been unlinked.  Adjust its
** size parameters for check-out and return a pointer to the
** user portion of the chunk.
*/


/*
** Change the size of an existing memory allocation.
**
** The outer layer memory allocator prevents this routine from
** being called with pPrior==0.
**
** nBytes is always a value obtained from a prior call to
** memsys5Round().  Hence nBytes is always a non-negative power
** of two.  If nBytes==0 that means that an oversize allocation
** (an allocation larger than 0x40000000) was requested and this
** routine should return 0 without freeing pPrior.
*/


/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated.
*/


/*
** Trigger the alarm
*/


/*
** Seek to the offset passed as the second argument, then read cnt
** bytes into pBuf. Return the number of bytes actually read.
**
** NB:  If you define USE_PREAD or USE_PREAD64, then it might also
** be necessary to define _XOPEN_SOURCE to be 500.  This varies from
** one system to another.  Since SQLite does not define USE_PREAD
** in any form by default, we will not attempt to define _XOPEN_SOURCE.
** See tickets #2741 and #2681.
**
** To avoid stomping the errno value on a failed read the lastErrno value
** is set before returning.
*/


/*
** Attempt to seek the file-descriptor passed as the first argument to
** absolute offset iOff, then attempt to write nBuf bytes of data from
** pBuf to it. If an error occurs, return -1 and set *piErrno. Otherwise,
** return the actual number of bytes written (which may be less than
** nBuf).
*/


/*
** Return the system page size.
**
** This function should not be called directly by other code in this file.
** Instead, it should be called via macro osGetpagesize().
*/


/*
** Attempt to set the size of the memory mapping maintained by file
** descriptor pFd to nNew bytes. Any existing mapping is discarded.
**
** If successful, this function sets the following variables:
**
**       unixFile.pMapRegion
**       unixFile.mmapSize
**       unixFile.mmapSizeActual
**
** If unsuccessful, an error message is logged via sqlite3_log() and
** the three variables above are zeroed. In this case SQLite should
** continue accessing the database using the xRead() and xWrite()
** methods.
*/


/*
** Memory map or remap the file opened by file-descriptor pFd (if the file
** is already mapped, the existing mapping is replaced by the new). Or, if
** there already exists a mapping for this file, and there are still
** outstanding xFetch() references to it, this function is a no-op.
**
** If parameter nByte is non-negative, then it is the requested size of
** the mapping to create. Otherwise, if nByte is less than zero, then the
** requested size is the size of the file on disk. The actual size of the
** created mapping is either the requested size or the value configured
** using SQLITE_FCNTL_MMAP_LIMIT, whichever is smaller.
**
** SQLITE_OK is returned if no error occurs (even if the mapping is not
** recreated as a result of outstanding references) or an SQLite error
** code otherwise.
*/


/*
** If possible, return a pointer to a mapping of file fd starting at offset
** iOff. The mapping must be valid for at least nAmt bytes.
**
** If such a pointer can be obtained, store it in *pp and return SQLITE_OK.
** Or, if one cannot but no error occurs, set *pp to 0 and return SQLITE_OK.
** Finally, if an error does occur, return an SQLite error code. The final
** value of *pp is undefined in this case.
**
** If this function does return a pointer, the caller must eventually
** release the reference by calling unixUnfetch().
*/


/*
** If the third argument is non-NULL, then this function releases a
** reference obtained by an earlier call to unixFetch(). The second
** argument passed to this function must be the same as the corresponding
** argument that was passed to the unixFetch() invocation.
**
** Or, if the third argument is NULL, then this function is being called
** to inform the VFS layer that, according to POSIX, any existing mapping
** may now be invalid and should be unmapped.
*/


/*
** This "finder" function attempts to determine the best locking strategy
** for the database file "filePath".  It then returns the sqlite3_io_methods
** object that implements that strategy.
**
** This is for MacOSX only.
*/


/*
** Find the current time (in Universal Coordinated Time).  Write into *piNow
** the current time and date as a Julian Day number times 86_400_000.  In
** other words, write into *piNow the number of milliseconds since the Julian
** epoch of noon in Greenwich on November 24, 4714 B.C according to the
** proleptic Gregorian calendar.
**
** On success, return SQLITE_OK.  Return SQLITE_ERROR if the time and date
** cannot be found.
*/


/*
** Malloc function used within this file to allocate space from the buffer
** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no
** such buffer exists or there is no space left in it, this function falls
** back to sqlite3Malloc().
**
** Multiple threads can run this routine at the same time.  Global variables
** in pcache1 need to be protected via mutex.
*/


/*
** Remove the page supplied as an argument from the hash table
** (PCache1.apHash structure) that it is currently stored in.
** Also free the page if freePage is true.
**
** The PGroup mutex must be held when this function is called.
*/


/*
** Implementation of the sqlite3_pcache.xShutdown method.
** Note that the static mutex allocated in xInit does
** not need to be freed.
*/


/*
** Implementation of the sqlite3_pcache.xPagecount method.
*/


/*
** Implementation of the sqlite3_pcache.xTruncate method.
**
** Discard all unpinned pages in the cache with a page number equal to
** or greater than parameter iLimit. Any pinned pages with a page number
** equal to or greater than iLimit are implicitly unpinned.
*/


/*
** Implementation of the sqlite3_pcache.xDestroy method.
**
** Destroy a cache allocated using pcache1Create().
*/


/*
** Allocate a new RowSetEntry object that is associated with the
** given RowSet.  Return a pointer to the new and completely uninitialized
** objected.
**
** In an OOM situation, the RowSet.db->mallocFailed flag is set and this
** routine returns NULL.
*/


/*
** Merge two lists of RowSetEntry objects.  Remove duplicates.
**
** The input lists are connected via pRight pointers and are
** assumed to each already be in sorted order.
*/


/*
** Lock the database file to level eLock, which must be either SHARED_LOCK,
** RESERVED_LOCK or EXCLUSIVE_LOCK. If the caller is successful, set the
** Pager.eLock variable to the new locking state.
**
** Except, if Pager.eLock is set to UNKNOWN_LOCK when this function is
** called, do not modify it unless the new locking state is EXCLUSIVE_LOCK.
** See the comment above the #define of UNKNOWN_LOCK for an explanation
** of this.
*/


/*
** Return the offset of the sector boundary at or immediately
** following the value in pPager->journalOff, assuming a sector
** size of pPager->sectorSize bytes.
**
** i.e for a sector size of 512:
**
**   Pager.journalOff          Return value
**   ---------------------------------------
**   0                         0
**   512                       512
**   100                       512
**   2000                      2048
**
*/


/*
** The journal file must be open when this function is called.
**
** This function is a no-op if the journal file has not been written to
** within the current transaction (i.e. if Pager.journalOff==0).
**
** If doTruncate is non-zero or the Pager.journalSizeLimit variable is
** set to 0, then truncate the journal file to zero bytes in size. Otherwise,
** zero the 28-byte header at the start of the journal file. In either case,
** if the pager is not in no-sync mode, sync the journal file immediately
** after writing or truncating it.
**
** If Pager.journalSizeLimit is set to a positive, non-zero value, and
** following the truncation or zeroing described above the size of the
** journal file in bytes is larger than this value, then truncate the
** journal file to Pager.journalSizeLimit bytes. The journal file does
** not need to be synced following this operation.
**
** If an IO error occurs, abandon processing and return the IO error code.
** Otherwise, return SQLITE_OK.
*/


/*
** Set the bit number pgno in the PagerSavepoint.pInSavepoint
** bitvecs of all open savepoints. Return SQLITE_OK if successful
** or SQLITE_NOMEM if a malloc failure occurs.
*/


/*
** This function is called whenever an IOERR or FULL error that requires
** the pager to transition into the ERROR state may ahve occurred.
** The first argument is a pointer to the pager structure, the second
** the error-code about to be returned by a pager API function. The
** value returned is a copy of the second argument to this function.
**
** If the second argument is SQLITE_FULL, SQLITE_IOERR or one of the
** IOERR sub-codes, the pager enters the ERROR state and the error code
** is stored in Pager.errCode. While the pager remains in the ERROR state,
** all major API calls on the Pager will immediately return Pager.errCode.
**
** The ERROR state indicates that the contents of the pager-cache
** cannot be trusted. This state can be cleared by completely discarding
** the contents of the pager-cache. If a transaction was active when
** the persistent error occurred, then the rollback journal may need
** to be replayed to restore the contents of the database file (as if
** it were a hot-journal).
*/


/*
** Execute a rollback if a transaction is active and unlock the
** database file.
**
** If the pager has already entered the ERROR state, do not attempt
** the rollback at this time. Instead, pager_unlock() is called. The
** call to pager_unlock() will discard all in-memory pages, unlock
** the database file and move the pager back to OPEN state. If this
** means that there is a hot-journal left in the file-system, the next
** connection to obtain a shared lock on the pager (which may be this one)
** will roll it back.
**
** If the pager has not already entered the ERROR state, but an IO or
** malloc error occurs during a rollback, then this will itself cause
** the pager to enter the ERROR state. Which will be cleared by the
** call to pager_unlock(), as described above.
*/


/*
** Parameter aData must point to a buffer of pPager->pageSize bytes
** of data. Compute and return a checksum based ont the contents of the
** page of data and the current value of pPager->cksumInit.
**
** This is not a real checksum. It is really just the sum of the
** random initial value (pPager->cksumInit) and every 200th byte
** of the page data, starting with byte offset (pPager->pageSize%200).
** Each byte is interpreted as an 8-bit unsigned integer.
**
** Changing the formula used to compute this checksum results in an
** incompatible journal file format.
**
** If journal corruption occurs due to a power failure, the most likely
** scenario is that one end or the other of the record will be changed.
** It is much less likely that the two ends of the journal record will be
** correct and the middle be corrupt.  Thus, this "checksum" scheme,
** though fast and simple, catches the mostly likely kind of corruption.
*/


/*
** Check if the *-wal file that corresponds to the database opened by pPager
** exists if the database is not empy, or verify that the *-wal file does
** not exist (by deleting it) if the database file is empty.
**
** If the database is not empty and the *-wal file exists, open the pager
** in WAL mode.  If the database is empty or if no *-wal file exists and
** if no error occurs, make sure Pager.journalMode is not set to
** PAGER_JOURNALMODE_WAL.
**
** Return SQLITE_OK or an error code.
**
** The caller must hold a SHARED lock on the database file to call this
** function. Because an EXCLUSIVE lock on the db file is required to delete
** a WAL on a none-empty database, this ensures there is no race condition
** between the xAccess() below and an xDelete() being executed by some
** other connection.
*/


/*
** Open a temporary file.
**
** Write the file descriptor into *pFile. Return SQLITE_OK on success
** or some other error code if we fail. The OS will automatically
** delete the temporary file when it is closed.
**
** The flags passed to the VFS layer xOpen() call are those specified
** by parameter vfsFlags ORed with the following:
**
**     SQLITE_OPEN_READWRITE
**     SQLITE_OPEN_CREATE
**     SQLITE_OPEN_EXCLUSIVE
**     SQLITE_OPEN_DELETEONCLOSE
*/


/*
** Try to obtain a lock of type locktype on the database file. If
** a similar or greater lock is already held, this function is a no-op
** (returning SQLITE_OK immediately).
**
** Otherwise, attempt to obtain the lock using sqlite3OsLock(). Invoke
** the busy callback if the lock is currently not available. Repeat
** until the busy callback returns false or until the attempt to
** obtain the lock succeeds.
**
** Return SQLITE_OK on success and an error code if we cannot obtain
** the lock. If the lock is obtained successfully, set the Pager.state
** variable to locktype before returning.
*/


/*
** This function is called before attempting a hot-journal rollback. It
** syncs the journal file to disk, then sets pPager->journalHdr to the
** size of the journal file so that the pager_playback() routine knows
** that the entire journal file has been synced.
**
** Syncing a hot-journal to disk before attempting to roll it back ensures
** that if a power-failure occurs during the rollback, the process that
** attempts rollback following system recovery sees the same journal
** content as this process.
**
** If everything goes as planned, SQLITE_OK is returned. Otherwise,
** an SQLite error code.
*/


/*
** Obtain a reference to a memory mapped page object for page number pgno.
** The new object will use the pointer pData, obtained from xFetch().
** If successful, set *ppPage to point to the new page reference
** and return SQLITE_OK. Otherwise, return an SQLite error code and set
** *ppPage to zero.
**
** Page references obtained by calling this function should be released
** by calling pagerReleaseMapPage().
*/


/*
** Release a reference to page pPg. pPg must have been returned by an
** earlier call to pagerAcquireMapPage().
*/


/* Verify that the database file has not be deleted or renamed out from
** under the pager.  Return SQLITE_OK if the database is still were it ought
** to be on disk.  Return non-zero (SQLITE_READONLY_DBMOVED or some other error
** code from sqlite3OsAccess()) if the database has gone missing.
*/


/*
** This function is called after transitioning from PAGER_UNLOCK to
** PAGER_SHARED state. It tests if there is a hot journal present in
** the file-system for the given pager. A hot journal is one that
** needs to be played back. According to this function, a hot-journal
** file exists if the following criteria are met:
**
**   * The journal file exists in the file system, and
**   * No process holds a RESERVED or greater lock on the database file, and
**   * The database file itself is greater than 0 bytes in size, and
**   * The first byte of the journal file exists and is not 0x00.
**
** If the current size of the database file is 0 but a journal file
** exists, that is probably an old journal left over from a prior
** database with the same name. In this case the journal file is
** just deleted using OsDelete, *pExists is set to 0 and SQLITE_OK
** is returned.
**
** This routine does not check if there is a master journal filename
** at the end of the file. If there is, and that master journal file
** does not exist, then the journal file is not really hot. In this
** case this routine will return a false-positive. The pager_playback()
** routine will discover that the journal file is not really hot and
** will not roll it back.
**
** If a hot-journal file is found to exist, *pExists is set to 1 and
** SQLITE_OK returned. If no hot-journal file is present, *pExists is
** set to 0 and SQLITE_OK returned. If an IO error occurs while trying
** to determine whether or not a hot-journal file exists, the IO error
** code is returned and the value of *pExists is undefined.
*/


/*
** Mark a single data page as writeable. The page is written into the
** main journal or sub-journal as required. If the page is written into
** one of the journals, the corresponding bit is set in the
** Pager.pInJournal bitvec and the PagerSavepoint.pInSavepoint bitvecs
** of any open savepoints as appropriate.
*/


/*
** Call sqlite3WalOpen() to open the WAL handle. If the pager is in
** exclusive-locking mode when this function is called, take an EXCLUSIVE
** lock on the database file and use heap-memory to store the wal-index
** in. Otherwise, use the normal shared-memory.
*/


/*
** This function encodes a single frame header and writes it to a buffer
** supplied by the caller. A frame-header is made up of a series of
** 4-byte big-endian integers, as follows:
**
**     0: Page number.
**     4: For commit records, the size of the database image in pages
**        after the commit. For all other records, zero.
**     8: Salt-1 (copied from the wal-header)
**    12: Salt-2 (copied from the wal-header)
**    16: Checksum-1.
**    20: Checksum-2.
*/


/*
** Query to see if Btree handle p may obtain a lock of type eLock
** (READ_LOCK or WRITE_LOCK) on the table with root-page iTab. Return
** SQLITE_OK if the lock may be obtained (by calling
** setSharedCacheTableLock()), or SQLITE_LOCKED if not.
*/


/*
** Release all the table locks (locks obtained via calls to
** the setSharedCacheTableLock() procedure) held by Btree object p.
**
** This function assumes that Btree p has an open read or write
** transaction. If it does not, then the BTS_PENDING flag
** may be incorrectly cleared.
*/


/*
** Set bit pgno of the BtShared.pHasContent bitvec. This is called
** when a page that previously contained data becomes a free-list leaf
** page.
**
** The BtShared.pHasContent bitvec exists to work around an obscure
** bug caused by the interaction of two useful IO optimizations surrounding
** free-list leaf pages:
**
**   1) When all data is deleted from a page and the page becomes
**      a free-list leaf page, the page is not written to the database
**      (as free-list leaf pages contain no meaningful data). Sometimes
**      such a page is not even journalled (as it will not be modified,
**      why bother journalling it?).
**
**   2) When a free-list leaf page is reused, its content is not read
**      from the database or written to the journal file (why should it
**      be, if it is not at all meaningful?).
**
** By themselves, these optimizations work fine and provide a handy
** performance boost to bulk delete or insert operations. However, if
** a page is moved to the free-list and then reused within the same
** transaction, a problem comes up. If the page is not journalled when
** it is moved to the free-list and it is also not journalled when it
** is extracted from the free-list and reused, then the original data
** may be lost. In the event of a rollback, it may not be possible
** to restore the database to its original configuration.
**
** The solution is the BtShared.pHasContent bitvec. Whenever a page is
** moved to become a free-list leaf page, the corresponding bit is
** set in the bitvec. Whenever a leaf page is extracted from the free-list,
** optimization 2 above is omitted if the corresponding bit is already
** set in BtShared.pHasContent. The contents of the bitvec are cleared
** at the end of every transaction.
*/


/*
** Save the positions of all cursors (except pExcept) that are open on
** the table with root-page iRoot.  "Saving the cursor position" means that
** the location in the btree is remembered in such a way that it can be
** moved back to the same spot after the btree has been modified.  This
** routine is called just before cursor pExcept is used to modify the
** table, for example in BtreeDelete() or BtreeInsert().
**
** If there are two or more cursors on the same btree, then all such
** cursors should have their BTCF_Multiple flag set.  The btreeCursor()
** routine enforces that rule.  This routine only needs to be called in
** the uncommon case when pExpect has the BTCF_Multiple flag set.
**
** If pExpect!=NULL and if no other cursors are found on the same root-page,
** then the BTCF_Multiple flag on pExpect is cleared, to avoid another
** pointless call to this routine.
**
** Implementation note:  This routine merely checks to see if any cursors
** need to be saved.  It calls out to saveCursorsOnList() in the (unusual)
** event that cursors are in need to being saved.
*/


/*
** Release a MemPage.  This should be called once for each prior
** call to btreeGetPage.
*/


/*
** Perform a single step of an incremental-vacuum. If successful, return
** SQLITE_OK. If there is no work to do (and therefore no point in
** calling this function again), return SQLITE_DONE. Or, if an error
** occurs, return some other error code.
**
** More specifically, this function attempts to re-organize the database so
** that the last page of the file currently in use is no longer in use.
**
** Parameter nFin is the number of pages that this database would contain
** were this function called until it returns SQLITE_DONE.
**
** If the bCommit parameter is non-zero, this function assumes that the
** caller will keep calling incrVacuumStep() until it returns SQLITE_DONE
** or an error. bCommit is passed true for an auto-vacuum-on-commit
** operation, or false for an incremental vacuum.
*/


/*
** The database opened by the first argument is an auto-vacuum database
** nOrig pages in size containing nFree free pages. Return the expected
** size of the database in pages following an auto-vacuum operation.
*/


/*
** Page pParent is an internal (non-leaf) tree page. This function
** asserts that page number iChild is the left-child if the iIdx'th
** cell in page pParent. Or, if iIdx is equal to the total number of
** cells in pParent, that page number iChild is the right-child of
** the page.
*/


/*
** This function does not contribute anything to the operation of SQLite.
** it is sometimes activated temporarily while debugging code responsible
** for setting pointer-map entries.
*/


/*
** An implementation of a min-heap.
**
** aHeap[0] is the number of elements on the heap.  aHeap[1] is the
** root element.  The daughter nodes of aHeap[N] are aHeap[N*2]
** and aHeap[N*2+1].
**
** The heap property is this:  Every node is less than or equal to both
** of its daughter nodes.  A consequence of the heap property is that the
** root node aHeap[1] is always the minimum value currently in the heap.
**
** The btreeHeapInsert() routine inserts an unsigned 32-bit number onto
** the heap, preserving the heap property.  The btreeHeapPull() routine
** removes the root element from the heap (the minimum value in the heap)
** and then moves other nodes around as necessary to preserve the heap
** property.
**
** This heap is used for cell overlap and coverage testing.  Each u32
** entry represents the span of a cell or freeblock on a btree page.
** The upper 16 bits are the index of the first byte of a range and the
** lower 16 bits are the index of the last byte of that range.
*/


/*
** If pFile is currently larger than iSize bytes, then truncate it to
** exactly iSize bytes. If pFile is not larger than iSize bytes, then
** this function is a no-op.
**
** Return SQLITE_OK if everything is successful, or an SQLite error
** code if an error occurs.
*/


/*
** Close all cursors.
**
** Also release any dynamic memory held by the VM in the Vdbe.aMem memory
** cell array. This is necessary as the memory cell array may contain
** pointers to VdbeFrame objects, which may in turn contain pointers to
** open cursors.
*/


/*
** If an SQLITE_CONFIG_SQLLOG hook is registered and the VM has been run,
** invoke it.
*/


/*
** Both *pMem1 and *pMem2 contain string values. Compare the two values
** using the collation sequence pColl. As usual, return a negative , zero
** or positive value if *pMem1 is less than, equal to or greater than
** *pMem2, respectively. Similar in spirit to "rc = (*pMem1) - (*pMem2);".
*/


/*
** The first argument passed to this function is a serial-type that
** corresponds to an integer - all values between 1 and 9 inclusive
** except 7. The second points to a buffer containing an integer value
** serialized according to serial_type. This function deserializes
** and returns the value.
*/


/*
** If the second argument is not NULL, release any allocations associated
** with the memory cells in the p->aMem[] array. Also free the UnpackedRecord
** structure itself, using sqlite3DbFree().
**
** This function is used to free UnpackedRecord structures allocated by
** the vdbeUnpackRecord() function found in vdbeapi.c.
*/


/*
** This function is called after invoking an sqlite3_value_XXX function on a
** column value (i.e. a value returned by evaluating an SQL expression in the
** select list of a SELECT statement) that may cause a malloc() failure. If
** malloc() has failed, the threads mallocFailed flag is cleared and the result
** code of statement pStmt set to SQLITE_NOMEM.
**
** Specifically, this is called from within:
**
**     sqlite3_column_int()
**     sqlite3_column_int64()
**     sqlite3_column_text()
**     sqlite3_column_text16()
**     sqlite3_column_real()
**     sqlite3_column_bytes()
**     sqlite3_column_bytes16()
**     sqiite3_column_blob()
*/


/*
** This function is only called from within an assert() expression. It
** checks that the sqlite3.nTransaction variable is correctly set to
** the number of non-transaction savepoints currently in the
** linked list starting at sqlite3.pSavepoint.
**
** Usage:
**
**     assert( checkSavepointCount(db) );
*/


/*
** Attempt to memory map file pFile. If successful, set *pp to point to the
** new mapping and return SQLITE_OK. If the mapping is not attempted
** (because the file is too large or the VFS layer is configured not to use
** mmap), return SQLITE_OK and set *pp to NULL.
**
** Or, if an error occurs, return an SQLite error code. The final value of
** *pp is undefined in this case.
*/


/*
** Attach PmaReader pReadr to file pFile (if it is not already attached to
** that file) and seek it to offset iOff within the file.  Return SQLITE_OK
** if successful, or an SQLite error code if an error occurs.
*/


/*
** Initialize PmaReader pReadr to scan through the PMA stored in file pFile
** starting at offset iStart and ending at offset iEof-1. This function
** leaves the PmaReader pointing to the first key in the PMA (or EOF if the
** PMA is empty).
**
** If the pnByte parameter is NULL, then it is assumed that the file
** contains a single PMA, and that that PMA omits the initial length varint.
*/


/*
** A version of vdbeSorterCompare() that assumes that it has already been
** determined that the first field of key1 is equal to the first field of
** key2.
*/


/*
** Compare key1 (buffer pKey1, size nKey1 bytes) with key2 (buffer pKey2,
** size nKey2 bytes). Use (pTask->pKeyInfo) for the collation sequences
** used by the comparison. Return the result of the comparison.
**
** If IN/OUT parameter *pbKey2Cached is true when this function is called,
** it is assumed that (pTask->pUnpacked) contains the unpacked version
** of key2. If it is false, (pTask->pUnpacked) is populated with the unpacked
** version of key2 and *pbKey2Cached set to true before returning.
**
** If an OOM error is encountered, (pTask->pUnpacked->error_rc) is set
** to SQLITE_NOMEM.
*/


/*
** Join all outstanding threads launched by SorterWrite() to create
** level-0 PMAs.
*/


/*
** Write the current contents of in-memory linked-list pList to a level-0
** PMA in the temp file belonging to sub-task pTask. Return SQLITE_OK if
** successful, or an SQLite error code otherwise.
**
** The format of a PMA is:
**
**     * A varint. This varint contains the total number of bytes of content
**       in the PMA (not including the varint itself).
**
**     * One or more records packed end-to-end in order of ascending keys.
**       Each record consists of a varint followed by a blob of data (the
**       key). The varint is the number of bytes in the blob of data.
*/


/*
** The main routine for vdbePmaReaderIncrMergeInit() operations run in
** background threads.
*/


/*
** Allocate a new MergeEngine object to merge the contents of nPMA level-0
** PMAs from pTask->file. If no error occurs, set *ppOut to point to
** the new object and return SQLITE_OK. Or, if an error does occur, set *ppOut
** to NULL and return an SQLite error code.
**
** When this function is called, *piOffset is set to the offset of the
** first PMA to read from pTask->file. Assuming no error occurs, it is
** set to the offset immediately following the last byte of the last
** PMA before returning. If an error does occur, then the final value of
** *piOffset is undefined.
*/


/*
** The argument is an IN operator with a list (not a subquery) on the
** right-hand side.  Return TRUE if that list is constant.
*/


/*
** Generate an instruction that will put the floating point
** value described by z[0..n-1] into register iMem.
**
** The z[] string will probably not be zero-terminated.  But the
** z[n] character is guaranteed to be something that does not look
** like the continuation of the number.
*/


/*
** Backwards Compatibility Hack:
**
** Historical versions of SQLite accepted strings as column names in
** indexes and PRIMARY KEY constraints and in UNIQUE constraints.  Example:
**
**     CREATE TABLE xyz(a,b,c,d,e,PRIMARY KEY('a'),UNIQUE('b','c' COLLATE trim)
**     CREATE INDEX abc ON xyz('c','d' DESC,'e' COLLATE nocase DESC);
**
** This is goofy.  But to preserve backwards compatibility we continue to
** accept it.  This routine does the necessary conversion.  It converts
** the expression given in its argument from a TK_STRING into a TK_ID
** if the expression is just a TK_STRING with an optional COLLATE clause.
** If the epxression is anything other than TK_STRING, the expression is
** unchanged.
*/


/*
** The first parameter is a pointer to an output buffer. The second
** parameter is a pointer to an integer that contains the offset at
** which to write into the output buffer. This function copies the
** nul-terminated string pointed to by the third parameter, zSignedIdent,
** to the specified offset in the buffer and updates *pIdx to refer
** to the first byte after the last byte written before returning.
**
** If the string zSignedIdent consists entirely of alpha-numeric
** characters, does not begin with a digit and is not an SQL keyword,
** then it is copied to the output buffer exactly as it is. Otherwise,
** it is quoted using double-quotes.
*/


/*
** Implementation of random().  Return a random integer.
*/


/*
** The unicode() function.  Return the integer unicode code-point value
** for the first character of the input string.
*/


/*
** Compute the soundex encoding of a word.
**
** IMP: R-59782-00072 The soundex(X) function returns a string that is the
** soundex encoding of the string X.
*/


/*
** The second argument is a Trigger structure allocated by the
** fkActionTrigger() routine. This function deletes the Trigger structure
** and all of its sub-components.
**
** The Trigger structure or any of its sub-components may be allocated from
** the lookaside buffer belonging to database handle dbMem.
*/


/*
** The second argument points to an FKey object representing a foreign key
** for which pTab is the child table. An UPDATE statement against pTab
** is currently being processed. For each column of the table that is
** actually updated, the corresponding element in the aChange[] array
** is zero or greater (if a column is unmodified the corresponding element
** is set to -1). If the rowid column is modified by the UPDATE statement
** the bChngRowid argument is non-zero.
**
** This function returns true if any of the columns that are part of the
** child key for FK constraint *p are modified.
*/


/* This is the Walker callback from checkConstraintUnchanged().  Set
** bit 0x01 of pWalker->eCode if
** pWalker->eCode to 0 if this expression node references any of the
** columns that are being modifed by an UPDATE statement.
*/


/*
** Pragma virtual table module xDisconnect method.
*/


/*
** Pragma virtual table module xRowid method.
*/


/*
** This function invokes either the xRollback or xCommit method
** of each of the virtual tables in the sqlite3.aVTrans array. The method
** called is identified by the second argument, "offset", which is
** the offset of the method to call in the sqlite3_module structure.
**
** The array is cleared after invoking the callbacks.
*/


/*
** Expression pRight, which is the RHS of a comparison operation, is
** either a vector of n elements or, if n==1, a scalar expression.
** Before the comparison operation, affinity zAff is to be applied
** to the pRight values. This function modifies characters within the
** affinity string to SQLITE_AFF_BLOB if either:
**
**   * the comparison will be performed with no affinity, or
**   * the affinity change in zAff is guaranteed not to change the value.
*/


/*
** If it is not NULL, pTerm is a term that provides an upper or lower
** bound on a range scan. Without considering pTerm, it is estimated
** that the scan will visit nNew rows. This function returns the number
** estimated to be visited after taking pTerm into account.
**
** If the user explicitly specified a likelihood() value for this term,
** then the return value is the likelihood multiplied by the number of
** input rows. Otherwise, this function assumes that an "IS NOT NULL" term
** has a likelihood of 0.50, and any other term a likelihood of 0.25.
*/


/*
** This function is called to estimate the number of rows visited by a
** range-scan on a skip-scan index. For example:
**
**   CREATE INDEX i1 ON t1(a, b, c);
**   SELECT * FROM t1 WHERE a=? AND c BETWEEN ? AND ?;
**
** Value pLoop->nOut is currently set to the estimated number of rows
** visited for scanning (a=? AND b=?). This function reduces that estimate
** by some factor to account for the (c BETWEEN ? AND ?) expression based
** on the stat4 data for the index. this scan will be peformed multiple
** times (once for each (a,b) combination that matches a=?) is dealt with
** by the caller.
**
** It does this by scanning through all stat4 samples, comparing values
** extracted from pLower and pUpper with the corresponding column in each
** sample. If L and U are the number of samples found to be less than or
** equal to the values extracted from pLower and pUpper respectively, and
** N is the total number of samples, the pLoop->nOut value is adjusted
** as follows:
**
**   nOut = nOut * ( min(U - L, 1) / N )
**
** If pLower is NULL, or a value cannot be extracted from the term, L is
** set to zero. If pUpper is NULL, or a value cannot be extracted from it,
** U is set to N.
**
** Normally, this function sets *pbDone to 1 before returning. However,
** if no value can be extracted from either pLower or pUpper (and so the
** estimate of the number of rows delivered remains unchanged), *pbDone
** is left as is.
**
** If an error occurs, an SQLite error code is returned. Otherwise,
** SQLITE_OK.
*/


/*
** Estimate the number of rows that will be returned based on
** an equality constraint x=VALUE and where that VALUE occurs in
** the histogram data.  This only works when x is the left-most
** column of an index and sqlite_stat3 histogram data is available
** for that index.  When pExpr==NULL that means the constraint is
** "x IS NULL" instead of "x=VALUE".
**
** Write the estimated row count into *pnRow and return SQLITE_OK.
** If unable to make an estimate, leave *pnRow unchanged and return
** non-zero.
**
** This routine can fail if it is unable to load a collating sequence
** required for string comparison, or if unable to allocate memory
** for a UTF conversion required for comparison.  The error is stored
** in the pParse structure.
*/


/*
** Estimate the number of rows that will be returned based on
** an IN constraint where the right-hand side of the IN operator
** is a list of values.  Example:
**
**        WHERE x IN (1,2,3,4)
**
** Write the estimated row count into *pnRow and return SQLITE_OK.
** If unable to make an estimate, leave *pnRow unchanged and return
** non-zero.
**
** This routine can fail if it is unable to load a collating sequence
** required for string comparison, or if unable to allocate memory
** for a UTF conversion required for comparison.  The error is stored
** in the pParse structure.
*/


/*
** Another built-in collating sequence: NOCASE.
**
** This collating sequence is intended to be used for "case independent
** comparison". SQLite's knowledge of upper and lower case equivalents
** extends only to the 26 characters used in the English language.
**
** At the moment there is only a UTF-8 implementation.
*/


/*
** Return TRUE if database connection db has unfinalized prepared
** statements or unfinished sqlite3_backup objects.
*/


/*
** This function is a complex assert() that verifies the following
** properties of the blocked connections list:
**
**   1) Each entry in the list has a non-NULL value for either
**      pUnlockConnection or pBlockingConnection, or both.
**
**   2) All entries in the list that share a common value for
**      xUnlockNotify are grouped together.
**
**   3) If the argument db is not NULL, then none of the entries in the
**      blocked connections list have pUnlockConnection or pBlockingConnection
**      set to db. This is used when closing connection db.
*/


/*
** Store the current database page-size in bytes in p->nPgsz.
**
** If *pRc is non-zero when this function is called, it is a no-op.
** Otherwise, if an error occurs, an SQLite error code is stored in *pRc
** before returning.
*/


/*
** Return a list of N comma separated question marks, where N is the number
** of columns in the %_content table (one for the docid plus one for each
** user-defined text column).
**
** If argument zFunc is not NULL, then all but the first question mark
** is preceded by zFunc and an open bracket, and followed by a closed
** bracket. For example, if zFunc is "zip" and the FTS3 table has three
** user-defined text columns, the following string is returned:
**
**     "?, zip(?), zip(?), zip(?)"
**
** The pointer returned points to a buffer allocated by sqlite3_malloc(). It
** is the responsibility of the caller to eventually free it.
**
** If *pRc is not SQLITE_OK when this function is called, it is a no-op (and
** a NULL pointer is returned). Otherwise, if an OOM error is encountered
** by this function, NULL is returned and *pRc is set to SQLITE_NOMEM. If
** no error occurs, *pRc is left unmodified.
*/


/*
** When this function is called, *ppPoslist is assumed to point to the
** start of a position-list. After it returns, *ppPoslist points to the
** first byte after the position-list.
**
** A position list is list of positions (delta encoded) and columns for
** a single document record of a doclist.  So, in other words, this
** routine advances *ppPoslist so that it points to the next docid in
** the doclist, or to the first byte past the end of the doclist.
**
** If pp is not NULL, then the contents of the position list are copied
** to *pp. *pp is set to point to the first byte past the last byte copied
** before this function returns.
*/


/*
** When this function is called, *ppPoslist is assumed to point to the
** start of a column-list. After it returns, *ppPoslist points to the
** to the terminator (POS_COLUMN or POS_END) byte of the column-list.
**
** A column-list is list of delta-encoded positions for a single column
** within a single document within a doclist.
**
** The column-list is terminated either by a POS_COLUMN varint (1) or
** a POS_END varint (0).  This routine leaves *ppPoslist pointing to
** the POS_COLUMN or POS_END that terminates the column-list.
**
** If pp is not NULL, then the contents of the column-list are copied
** to *pp. *pp is set to point to the first byte past the last byte copied
** before this function returns.  The POS_COLUMN or POS_END terminator
** is not copied into *pp.
*/


/*
** If parameter iCol is not 0, write an POS_COLUMN (1) byte followed by
** the value of iCol encoded as a varint to *pp.   This will start a new
** column list.
**
** Set *pp to point to the byte just after the last byte written before
** returning (do not modify it if iCol==0). Return the total number of bytes
** written (0 if iCol==0).
*/


/*
** Merge two position-lists as required by the NEAR operator. The argument
** position lists correspond to the left and right phrases of an expression
** like:
**
**     "phrase 1" NEAR "phrase number 2"
**
** Position list *pp1 corresponds to the left-hand side of the NEAR
** expression and *pp2 to the right. As usual, the indexes in the position
** lists are the offsets of the last token in each phrase (tokens "1" and "2"
** in the example above).
**
** The output position list - written to *pp - is a copy of *pp2 with those
** entries that are not sufficiently NEAR entries in *pp1 removed.
*/


/*
** This function counts the total number of docids in the doclist stored
** in buffer aList[], size nList bytes.
**
** If the isPoslist argument is true, then it is assumed that the doclist
** contains a position-list following each docid. Otherwise, it is assumed
** that the doclist is simply a list of docids stored as delta encoded
** varints.
*/


/*
** This is the xEof method of the virtual table. SQLite calls this
** routine to find out if it has reached the end of a result set.
*/


/*
** This is the xRowid method. The SQLite core calls this routine to
** retrieve the rowid for the current row of the result set. fts3
** exposes %_content.docid as the rowid for the virtual table. The
** rowid should be written to *pRowid.
*/


/*
** This function is the implementation of the xUpdate callback used by
** FTS3 virtual tables. It is invoked by SQLite each time a row is to be
** inserted, updated or deleted.
*/


/*
** Helper function used by the implementation of the overloaded snippet(),
** offsets() and optimize() SQL functions.
**
** If the value passed as the third argument is a blob of size
** sizeof(Fts3Cursor*), then the blob contents are copied to the
** output variable *ppCsr and SQLITE_OK is returned. Otherwise, an error
** message is written to context pContext and SQLITE_ERROR returned. The
** string passed via zFunc is used as part of the error message.
*/


/*
** Implementation of the special optimize() function for FTS3. This
** function merges all segments in the database to a single segment.
** Example usage is:
**
**   SELECT optimize(t) FROM t LIMIT 1;
**
** where 't' is the name of an FTS3 table.
*/


/*
** Token pToken is an incrementally loaded token that is part of a
** multi-token phrase. Advance it to the next matching document in the
** database and populate output variable *p with the details of the new
** entry. Or, if the iterator has reached EOF, set *pbEof to true.
**
** If an error occurs, return an SQLite error code. Otherwise, return
** SQLITE_OK.
*/


/*
** Restart interation for expression pExpr so that the next call to
** fts3EvalNext() visits the first row. Do not allow incremental
** loading or merging of phrase doclists for this iteration.
**
** If *pRc is other than SQLITE_OK when this function is called, it is
** a no-op. If an error occurs within this function, *pRc is set to an
** SQLite error code before returning.
*/


/*
** Argument ppHead contains a pointer to the current head of a query
** expression tree being parsed. pPrev is the expression node most recently
** inserted into the tree. This function adds pNew, which is always a binary
** operator node, into the expression tree based on the relative precedence
** of pNew and the existing nodes of the tree. This may result in the head
** of the tree changing, in which case *ppHead is set to the new root node.
*/


/*
** This function is similar to sqlite3Fts3ExprParse(), with the following
** differences:
**
**   1. It does not do expression rebalancing.
**   2. It does not check that the expression does not exceed the
**      maximum allowable depth.
**   3. Even if it fails, *ppExpr may still be set to point to an
**      expression tree. It should be deleted using sqlite3Fts3ExprFree()
**      in this case.
*/


/* Resize the hash table so that it cantains "new_size" buckets.
** "new_size" must be a power of 2.  The hash table might fail
** to resize if sqliteMalloc() fails.
**
** Return non-zero if a memory allocation error occurs.
*/


/*
** Prepare to begin tokenizing a particular string.  The input
** string to be tokenized is zInput[0..nInput-1].  A cursor
** used to incrementally tokenize this string is returned in
** *ppCursor.
*/


/*
** If the word ends with zFrom and xCond() is true for the stem
** of the word that preceeds the zFrom ending, then change the
** ending to zTo.
**
** The input word *pz and zFrom are both in reverse order.  zTo
** is in normal order.
**
** Return TRUE if zFrom matches.  Return FALSE if zFrom does not
** match.  Not that TRUE is returned even if xCond() fails and
** no substitution occurs.
*/


/*
** Implementation of a special SQL scalar function for testing tokenizers
** designed to be used in concert with the Tcl testing framework. This
** function must be called with two or more arguments:
**
**   SELECT <function-name>(<key-name>, ..., <input-string>);
**
** where <function-name> is the name passed as the second argument
** to the sqlite3Fts3InitHashTable() function (e.g. 'fts3_tokenizer')
** concatenated with the string '_test' (e.g. 'fts3_tokenizer_test').
**
** The return value is a string that may be interpreted as a Tcl
** list. For each token in the <input-string>, three elements are
** added to the returned list. The first is the token position, the
** second is the token text (folded, stemmed, etc.) and the third is the
** substring of <input-string> associated with the token. For example,
** using the built-in "simple" tokenizer:
**
**   SELECT fts_tokenizer_test('simple', 'I don't see how');
**
** will return the string:
**
**   "{0 i I 1 dont don't 2 see see 3 how how}"
**
*/


/*
** Prepare to begin tokenizing a particular string.  The input
** string to be tokenized is pInput[0..nBytes-1].  A cursor
** used to incrementally tokenize this string is returned in
** *ppCursor.
*/


/*
** This function ensures that the caller has obtained an exclusive
** shared-cache table-lock on the %_segdir table. This is required before
** writing data to the fts3 table. If this lock is not acquired first, then
** the caller may end up attempting to take this lock as part of committing
** a transaction, causing SQLite to return SQLITE_LOCKED or
** LOCKED_SHAREDCACHEto a COMMIT command.
**
** It is best to avoid this because if FTS3 returns any error when
** committing a transaction, the whole transaction will be rolled back.
** And this is not what users expect when they get SQLITE_LOCKED_SHAREDCACHE.
** It can still happen if the user locks the underlying tables directly
** instead of accessing them via FTS.
*/


/*
** Compare the term that the Fts3SegReader object passed as the first argument
** points to with the term specified by arguments zTerm and nTerm.
**
** If the pSeg iterator is already at EOF, return 0. Otherwise, return
** -ve if the pSeg term is less than zTerm/nTerm, 0 if the two terms are
** equal, or +ve if the pSeg term is greater than zTerm/nTerm.
*/


/*
** Write the buffer for the segment node pTree and all of its peers to the
** database. Then call this function recursively to write the parent of
** pTree and its peers to the database.
**
** Except, if pTree is a root node, do not write it to the database. Instead,
** set output variables *paRoot and *pnRoot to contain the root node.
**
** If successful, SQLITE_OK is returned and output variable *piLast is
** set to the largest blockid written to the database (or zero if no
** blocks were written to the db). Otherwise, an SQLite error code is
** returned.
*/


/*
** Release all memory held by the SegmentWriter object passed as the
** first argument.
*/


/*
** Query to see if the entry in the %_segments table with blockid iEnd is
** NULL. If no error occurs and the entry is NULL, set *pbRes 1 before
** returning. Otherwise, set *pbRes to 0.
**
** Or, if an error occurs while querying the database, return an SQLite
** error code. The final value of *pbRes is undefined in this case.
**
** This is used to test if a segment is an "appendable" segment. If it
** is, then a NULL entry has been inserted into the %_segments table
** with blockid %_segdir.end_block.
*/


/*
** Remove an entry from the %_segdir table. This involves running the
** following two statements:
**
**   DELETE FROM %_segdir WHERE level = :iAbsLevel AND idx = :iIdx
**   UPDATE %_segdir SET idx = idx - 1 WHERE level = :iAbsLevel AND idx > :iIdx
**
** The DELETE statement removes the specific %_segdir level. The UPDATE
** statement ensures that the remaining segments have contiguously allocated
** idx values.
*/


/*
** If *pRc is not SQLITE_OK when this function is called, it is a no-op.
** Otherwise, append an entry to the hint stored in blob *pHint. Each entry
** consists of two varints, the absolute level number of the input segments
** and the number of input segments.
**
** If successful, leave *pRc set to SQLITE_OK and return. If an error occurs,
** set *pRc to an SQLite error code before returning.
*/


/*
** Convert the text beginning at *pz into an integer and return
** its value.  Advance *pz to point to the first character past
** the integer.
**
** This function used for parameters to merge= and incrmerge=
** commands.
*/


/*
** Run the integrity-check. If no error occurs and the current contents of
** the FTS index are correct, return SQLITE_OK. Or, if the contents of the
** FTS index are incorrect, return SQLITE_CORRUPT_VTAB.
**
** Or, if an error (e.g. an OOM or IO error) occurs, return an SQLite
** error code.
**
** The integrity-check works as follows. For each token and indexed token
** prefix in the document set, a 64-bit checksum is calculated (by code
** in fts3ChecksumEntry()) based on the following:
**
**     + The index number (0 for the main index, 1 for the first prefix
**       index etc.),
**     + The token (or token prefix) text itself,
**     + The language-id of the row it appears in,
**     + The docid of the row it appears in,
**     + The column it appears in, and
**     + The tokens position within that column.
**
** The checksums for all entries in the index are XORed together to create
** a single checksum for the entire index.
**
** The integrity-check code calculates the same checksum in two ways:
**
**     1. By scanning the contents of the FTS index, and
**     2. By scanning and tokenizing the content table.
**
** If the two checksums are identical, the integrity-check is deemed to have
** passed.
*/


/*
** Iterate through all phrase nodes in an FTS3 query, except those that
** are part of a sub-tree that is the right-hand-side of a NOT operator.
** For each phrase node found, the supplied callback function is invoked.
**
** If the callback function returns anything other than SQLITE_OK,
** the iteration is abandoned and the error code returned immediately.
** Otherwise, SQLITE_OK is returned after a callback has been made for
** all eligible phrase nodes.
*/


/*
** Load the doclists for each phrase in the query associated with FTS3 cursor
** pCsr.
**
** If pnPhrase is not NULL, then *pnPhrase is set to the number of matchable
** phrases in the expression (all phrases except those directly or
** indirectly descended from the right-hand-side of a NOT operator). If
** pnToken is not NULL, then it is set to the number of tokens in all
** matchable phrases of the expression.
*/


/*
** This function is used to count the entries in a column-list (a
** delta-encoded list of term offsets within a single column of a single
** row). When this function is called, *ppCollist should point to the
** beginning of the first varint in the column-list (the varint that
** contains the position of the first matching term in the column data).
** Before returning, *ppCollist is set to point to the first byte after
** the last varint in the column-list (either the 0x00 signifying the end
** of the position-list, or the 0x01 that precedes the column number of
** the next column in the position-list).
**
** The number of elements in the column-list is returned.
*/


/*
** fts3ExprIterate() callback used to collect the "global" matchinfo stats
** for a single query.
**
** fts3ExprIterate() callback to load the 'global' elements of a
** FTS3_MATCHINFO_HITS matchinfo array. The global stats are those elements
** of the matchinfo array that are constant for all rows returned by the
** current query.
**
** Argument pCtx is actually a pointer to a struct of type MatchInfo. This
** function populates Matchinfo.aMatchinfo[] as follows:
**
**   for(iCol=0; iCol<nCol; iCol++){
**     aMatchinfo[3*iPhrase*nCol + 3*iCol + 1] = X;
**     aMatchinfo[3*iPhrase*nCol + 3*iCol + 2] = Y;
**   }
**
** where X is the number of matches for phrase iPhrase is column iCol of all
** rows of the table. Y is the number of rows for which column iCol contains
** at least one instance of phrase iPhrase.
**
** If the phrase pExpr consists entirely of deferred tokens, then all X and
** Y values are set to nDoc, where nDoc is the number of documents in the
** file system. This is done because the full-text index doclist is required
** to calculate these values properly, and the full-text index doclist is
** not available for deferred tokens.
*/


/*
** fts3ExprIterate() callback used to collect the "local" part of the
** FTS3_MATCHINFO_HITS array. The local stats are those elements of the
** array that are different for each row returned by the query.
*/


/*
** Rtree virtual table module xCreate method.
*/


/*
** Rtree virtual table module xConnect method.
*/


/*
** Use nodeAcquire() to obtain the leaf node containing the record with
** rowid iRowid. If successful, set *ppLeaf to point to the node and
** return SQLITE_OK. If there is no such record in the table, set
** *ppLeaf to 0 and return SQLITE_OK. If an error occurs, set *ppLeaf
** to zero and return an SQLite error code.
*/


/*
** This function is called when an ICU function called from within
** the implementation of an SQL scalar function returns an error.
**
** The scalar function context passed as the first argument is
** loaded with an error message based on the following two args.
*/


/*
** Implementation of SQLite REGEXP operator. This scalar function takes
** two arguments. The first is a regular expression pattern to compile
** the second is a string to match against that pattern. If either
** argument is an SQL NULL, then NULL Is returned. Otherwise, the result
** is 1 if the string matches the pattern, or 0 otherwise.
**
** SQLite maps the regexp() function to the regexp() operator such
** that the following two are equivalent:
**
**     zString REGEXP zPattern
**     regexp(zPattern, zString)
**
** Uses the following ICU regexp APIs:
**
**     uregex_open()
**     uregex_matches()
**     uregex_close()
*/


/*
** Implementations of scalar functions for case mapping - upper() and
** lower(). Function upper() converts its input to upper-case (ABC).
** Function lower() converts to lower-case (abc).
**
** ICU provides two types of case mapping, "general" case mapping and
** "language specific". Refer to ICU documentation for the differences
** between the two.
**
** To utilise "general" case mapping, the upper() or lower() scalar
** functions are invoked with one argument:
**
**     upper('ABC') -> 'abc'
**     lower('abc') -> 'ABC'
**
** To access ICU "language specific" case mapping, upper() or lower()
** should be invoked with two arguments. The second argument is the name
** of the locale to use. Passing an empty string ("") or SQL NULL value
** as the second argument is the same as invoking the 1 argument version
** of upper() or lower().
**
**     lower('I', 'en_us') -> 'i'
**     lower('I', 'tr_tr') -> '\u131' (small dotless i)
**
** http://www.icu-project.org/userguide/posix.html#case_mappings
*/


/*
** Advance the iterator to the next position.
**
** If no error occurs, SQLITE_OK is returned and the iterator is left
** pointing to the next entry. Otherwise, an error code and message is
** left in the RBU handle passed as the first argument. A copy of the
** error code is returned.
*/


/*
** This is a wrapper around "sqlite3_mprintf(zFmt, ...)". If an OOM occurs,
** an error code is stored in the RBU handle passed as the first argument.
**
** If an error has already occurred (p->rc is already set to something other
** than SQLITE_OK), then this function returns NULL without modifying the
** stored error code. In this case it still calls sqlite3_free() on any
** printf() parameters associated with %z conversions.
*/


/*
** This function constructs and returns a pointer to a nul-terminated
** string containing some SQL clause or list based on one or more of the
** column names currently stored in the pIter->azTblCol[] array.
*/


/*
** The iterator currently points to a table (not index) of type
** RBU_PK_WITHOUT_ROWID. This function creates the PRIMARY KEY
** declaration for the corresponding imposter table. For example,
** if the iterator points to a table created as:
**
**   CREATE TABLE t1(a, b, c, PRIMARY KEY(b, a DESC)) WITHOUT ROWID
**
** this function returns:
**
**   PRIMARY KEY("b", "a" DESC)
*/


/*
** Return the current wal-index header checksum for the target database
** as a 64-bit integer.
**
** The checksum is store in the first page of xShmMap memory as an 8-byte
** blob starting at byte offset 40.
*/


/*
** Read and return an unsigned 32-bit big-endian integer from the buffer
** passed as the only argument.
*/


/*
** Open a new statvfs cursor.
*/


/*
** Close a statvfs cursor.
*/


/*
** Append the hash of the blob passed via the second and third arguments to
** the hash-key value passed as the first. Return the new hash-key value.
*/


/*
** This is a helper function used by sessionMergeUpdate().
**
** When this function is called, both *paOne and *paTwo point to a value
** within a change record. Before it returns, both have been advanced so
** as to point to the next value in the record.
**
** If, when this function is called, *paTwo points to a valid value (i.e.
** *paTwo[0] is not 0x00 - the "no value" placeholder), a copy of the *paTwo
** pointer is returned and *pnVal is set to the number of bytes in the
** serialized value. Otherwise, a copy of *paOne is returned and *pnVal
** set to the number of bytes in the value at *paOne. If *paOne points
** to the "no value" placeholder, *pnVal is set to 1. In other words:
**
**   if( *paTwo is valid ) return *paTwo;
**   return *paOne;
**
*/


/*
** This function is a no-op if *pRc is other than SQLITE_OK when it is
** called. Otherwise, append a single byte to the buffer.
**
** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
** returning.
*/


/*
** This function is a no-op if *pRc is other than SQLITE_OK when it is
** called. Otherwise, append a single varint to the buffer.
**
** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
** returning.
*/


/*
** This function is a no-op if *pRc is other than SQLITE_OK when it is
** called. Otherwise, append the string representation of integer iVal
** to the buffer. No nul-terminator is written.
**
** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
** returning.
*/


/*
** This function is a no-op if *pRc is other than SQLITE_OK when it is
** called. Otherwise, append the string zStr enclosed in quotes (") and
** with any embedded quote characters escaped to the buffer. No
** nul-terminator byte is written.
**
** If an OOM condition is encountered, set *pRc to SQLITE_NOMEM before
** returning.
*/


/*
** This function is a no-op if *pRc is set to other than SQLITE_OK when it
** is called. Otherwise, append a serialized table header (part of the binary
** changeset format) to buffer *pBuf. If an error occurs, set *pRc to an
** SQLite error code before returning.
*/


/*
** A wrapper around sqlite3_bind_value() that detects an extra problem.
** See comments in the body of this function for details.
*/


/* Report an out-of-memory (OOM) condition
*/


/*
** Append a function parameter value to the JSON string under
** construction.
*/


/*
** Turn parser tracing on by giving a stream to which to write the trace
** and a prompt to preface each trace message.  Tracing is turned off
** by making either argument NULL
**
** Inputs:
** <ul>
** <li> A FILE* to which trace output should be written.
**      If NULL, then tracing is turned off.
** <li> A prefix string written at the beginning of every
**      line of trace output.  If NULL, then tracing is
**      turned off.
** </ul>
**
** Outputs:
** None.
*/


/*
** Deallocate and destroy a parser.  Destructors are called for
** all stack elements before shutting the parser down.
**
** If the fts5YYPARSEFREENEVERNULL macro exists (for example because it
** is defined in a %include section of the input grammar) then it is
** assumed that the input pointer is never NULL.
*/


/*
** Initialize the iterator object indicated by the final parameter to
** iterate through coalesced phrase instances in column iCol.
*/


/*
** Return a nul-terminated copy of the string indicated by pIn. If nIn
** is non-negative, then it is the length of the string in bytes. Otherwise,
** the length of the string is determined using strlen().
**
** It is the responsibility of the caller to eventually free the returned
** buffer using sqlite3_free(). If an OOM error occurs, NULL is returned.
*/


/*
** Argument pIn points to a character that is part of a nul-terminated
** string. Return a pointer to the first character following *pIn in
** the string that is not a white-space character.
*/


/*
** Argument pIn points to a character that is part of a nul-terminated
** string. Return a pointer to the first character following *pIn in
** the string that is not a "bareword" character.
*/


/*
** Tokenize the text passed via the second and third arguments.
**
** The callback is invoked once for each token in the input text. The
** arguments passed to it are, in order:
**
**     void *pCtx          // Copy of 4th argument to sqlite3Fts5Tokenize()
**     const char *pToken  // Pointer to buffer containing token
**     int nToken          // Size of token in bytes
**     int iStart          // Byte offset of start of token within input text
**     int iEnd            // Byte offset of end of token within input text
**     int iPos            // Position of token in input (first token is 0)
**
** If the callback returns a non-zero value the tokenization is abandoned
** and no further callbacks are issued.
**
** This function returns SQLITE_OK if successful or an SQLite error code
** if an error occurs. If the tokenization was abandoned early because
** the callback returned SQLITE_DONE, this is not an error and this function
** still returns SQLITE_OK. Or, if the tokenization was abandoned early
** because the callback returned another non-zero value, it is assumed
** to be an SQLite error code and returned to the caller.
*/


/*
** Move to the next document
**
** Return SQLITE_OK if successful, or an SQLite error code otherwise. It
** is not considered an error if the query does not match any documents.
*/


/*
** Release a reference to an Fts5Structure object returned by an earlier
** call to fts5StructureRead() or fts5StructureDecode().
*/


/*
** Return a copy of index structure pStruct. Except, promote as many
** segments as possible to level iPromote. If an OOM occurs, NULL is
** returned.
*/


/*
** A new segment has just been written to level iLvl of index structure
** pStruct. This function determines if any segments should be promoted
** as a result. Segments are promoted in two scenarios:
**
**   a) If the segment just written is smaller than one or more segments
**      within the previous populated level, it is promoted to the previous
**      populated level.
**
**   b) If the segment just written is larger than the newest segment on
**      the next populated level, then that segment, and any other adjacent
**      segments that are also smaller than the one just written, are
**      promoted.
**
** If one or more segments are promoted, the structure object is updated
** to reflect this.
*/