pCtx->pList = pToken;
      pCtx->nList++;
      break;
    }
  }
}






static int renameColumnSelectCb(Walker *pWalker, Select *p){
  return WRC_Continue;
}


/*
** This is a Walker expression callback.
**
** For every TK_COLUMN node in the expression tree, search to see
** if the column being references is the column being renamed by an
** ALTER TABLE statement.  If it is, then attach its associated
................................................................................
    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
  }
  return WRC_Continue;
}

/*
** The RenameCtx contains a list of tokens that reference a column that
** is being renamed by an ALTER TABLE statement.  Return the "first"
** RenameToken in the RenameCtx and remove that RenameToken from the
** RenameContext.  "First" means the first RenameToken encountered when
** the input SQL from left to right.  Repeated calls to this routine
** return all column name tokens in the order that they are encountered
** in the SQL statement.
*/
static RenameToken *renameColumnTokenNext(RenameCtx *pCtx){
  RenameToken *pBest = pCtx->pList;
  RenameToken *pToken;
  RenameToken **pp;
................................................................................
    if( pToken->t.z>pBest->t.z ) pBest = pToken;
  }
  for(pp=&pCtx->pList; *pp!=pBest; pp=&(*pp)->pNext);
  *pp = pBest->pNext;

  return pBest;
}




























/*
** SQL function:
**
**     sqlite_rename_column(zSql, iCol, bQuote, zNew, zTable, zOld)
**
**   0. zSql:     SQL statement to rewrite
................................................................................
  if( iCol<0 ) return;
  pTab = sqlite3FindTable(db, zTable, zDb);
  if( pTab==0 || iCol>=pTab->nCol ) return;
  zOld = pTab->aCol[iCol].zName;
  memset(&sCtx, 0, sizeof(sCtx));
  sCtx.iCol = ((iCol==pTab->iPKey) ? -1 : iCol);




  memset(&sParse, 0, sizeof(sParse));
  sParse.eParseMode = PARSE_MODE_RENAME_COLUMN;
  sParse.db = db;
  sParse.nQueryLoop = 1;
  rc = sqlite3RunParser(&sParse, zSql, &zErr);
  assert( sParse.pNewTable==0 || sParse.pNewIndex==0 );



  if( db->mallocFailed ) rc = SQLITE_NOMEM;
  if( rc==SQLITE_OK 
   && sParse.pNewTable==0 && sParse.pNewIndex==0 && sParse.pNewTrigger==0 
  ){
    rc = SQLITE_CORRUPT_BKPT;
  }

  if( rc==SQLITE_OK ){
    zQuot = sqlite3_mprintf("\"%w\"", zNew);
    if( zQuot==0 ){
      rc = SQLITE_NOMEM;
    }else{
      nQuot = sqlite3Strlen30(zQuot);
    }
  }

  if( bQuote ){
    zNew = zQuot;
    nNew = nQuot;
  }

#ifdef SQLITE_DEBUG


  assert( sqlite3Strlen30(zSql)==nSql );
  if( rc==SQLITE_OK ){
    RenameToken *pToken;
    for(pToken=sParse.pRename; pToken; pToken=pToken->pNext){
      assert( pToken->t.z>=zSql && &pToken->t.z[pToken->t.n]<=&zSql[nSql] );
    }
  }
#endif



















  /* Find tokens that need to be replaced. */
  memset(&sWalker, 0, sizeof(Walker));
  sWalker.pParse = &sParse;
  sWalker.xExprCallback = renameColumnExprCb;
  sWalker.xSelectCallback = renameColumnSelectCb;
  sWalker.u.pRename = &sCtx;
................................................................................
    Select *pSelect = sParse.pNewTable->pSelect;
    if( pSelect ){
      sParse.rc = SQLITE_OK;
      sqlite3SelectPrep(&sParse, sParse.pNewTable->pSelect, 0);
      rc = (db->mallocFailed ? SQLITE_NOMEM : sParse.rc);
      if( rc==SQLITE_OK ){
        sqlite3WalkSelect(&sWalker, pSelect);
      }else if( rc==SQLITE_ERROR ){
        /* Failed to resolve all symbols in the view. This is not an 
        ** error, but it will not be edited. */
        sqlite3DbFree(db, sParse.zErrMsg);
        sParse.zErrMsg = 0;
        rc = SQLITE_OK;
      }
      if( rc!=SQLITE_OK ) goto renameColumnFunc_done;
    }else{
      /* A regular table */
      int bFKOnly = sqlite3_stricmp(zTable, sParse.pNewTable->zName);
      FKey *pFKey;
      assert( sParse.pNewTable->pSelect==0 );
................................................................................
        sqlite3WalkExprList(&sWalker, pUpsert->pUpsertSet);
        sqlite3WalkExpr(&sWalker, pUpsert->pUpsertWhere);
        sqlite3WalkExpr(&sWalker, pUpsert->pUpsertTargetWhere);
      }
    }
  }





  assert( rc==SQLITE_OK );
  assert( nQuot>=nNew );
  zOut = sqlite3DbMallocZero(db, nSql + sCtx.nList*nQuot + 1);
  if( zOut ){
    int nOut = nSql;
    memcpy(zOut, zSql, nSql);
    while( sCtx.pList ){
................................................................................
    sqlite3DbFree(db, zOut);
  }else{
    rc = SQLITE_NOMEM;
  }

renameColumnFunc_done:
  if( rc!=SQLITE_OK ){
    if( zErr ){
      sqlite3_result_error(context, zErr, -1);
    }else{
      sqlite3_result_error_code(context, rc);
    }
  }

  if( sParse.pVdbe ){
    sqlite3VdbeFinalize(sParse.pVdbe);
  }
  sqlite3DeleteTable(db, sParse.pNewTable);
  if( sParse.pNewIndex ) sqlite3FreeIndex(db, sParse.pNewIndex);
  sqlite3DeleteTrigger(db, sParse.pNewTrigger);
  renameTokenFree(db, sParse.pRename);
  renameTokenFree(db, sCtx.pList);

  sqlite3ParserReset(&sParse);
  sqlite3_free(zQuot);
}

/*
** Register built-in functions used to help implement ALTER TABLE
*/

      pCtx->pList = pToken;
      pCtx->nList++;
      break;
    }
  }
}

/*
** This is a Walker select callback. It does nothing. It is only required
** because without a dummy callback, sqlite3WalkExpr() and similar do not
** descend into sub-select statements.
*/
static int renameColumnSelectCb(Walker *pWalker, Select *p){
  return WRC_Continue;
}


/*
** This is a Walker expression callback.
**
** For every TK_COLUMN node in the expression tree, search to see
** if the column being references is the column being renamed by an
** ALTER TABLE statement.  If it is, then attach its associated
................................................................................
    renameTokenFind(pWalker->pParse, p, (void*)pExpr);
  }
  return WRC_Continue;
}

/*
** The RenameCtx contains a list of tokens that reference a column that
** is being renamed by an ALTER TABLE statement.  Return the "last"
** RenameToken in the RenameCtx and remove that RenameToken from the
** RenameContext.  "Last" means the last RenameToken encountered when
** the input SQL is parsed from left to right.  Repeated calls to this routine
** return all column name tokens in the order that they are encountered
** in the SQL statement.
*/
static RenameToken *renameColumnTokenNext(RenameCtx *pCtx){
  RenameToken *pBest = pCtx->pList;
  RenameToken *pToken;
  RenameToken **pp;
................................................................................
    if( pToken->t.z>pBest->t.z ) pBest = pToken;
  }
  for(pp=&pCtx->pList; *pp!=pBest; pp=&(*pp)->pNext);
  *pp = pBest->pNext;

  return pBest;
}

/*
** An error occured while parsing or otherwise processing a database
** object (either pParse->pNewTable, pNewIndex or pNewTrigger) as part of an
** ALTER TABLE RENAME COLUMN program. The error message emitted by the
** sub-routine is currently stored in pParse->zErrMsg. This function
** adds context to the error message and then stores it in pCtx.
*/
static void renameColumnParseError(sqlite3_context *pCtx, Parse *pParse){
  const char *zT;
  const char *zN;
  char *zErr;
  if( pParse->pNewTable ){
    zT = pParse->pNewTable->pSelect ? "view" : "table";
    zN = pParse->pNewTable->zName;
  }else if( pParse->pNewIndex ){
    zT = "index";
    zN = pParse->pNewIndex->zName;
  }else{
    assert( pParse->pNewTrigger );
    zT = "trigger";
    zN = pParse->pNewTrigger->zName;
  }
  zErr = sqlite3_mprintf("error processing %s %s: %s", zT, zN, pParse->zErrMsg);
  sqlite3_result_error(pCtx, zErr, -1);
  sqlite3_free(zErr);
}

/*
** SQL function:
**
**     sqlite_rename_column(zSql, iCol, bQuote, zNew, zTable, zOld)
**
**   0. zSql:     SQL statement to rewrite
................................................................................
  if( iCol<0 ) return;
  pTab = sqlite3FindTable(db, zTable, zDb);
  if( pTab==0 || iCol>=pTab->nCol ) return;
  zOld = pTab->aCol[iCol].zName;
  memset(&sCtx, 0, sizeof(sCtx));
  sCtx.iCol = ((iCol==pTab->iPKey) ? -1 : iCol);

  /* Parse the SQL statement passed as the first argument. If no error
  ** occurs and the parse does not result in a new table, index or
  ** trigger object, the database must be corrupt. */
  memset(&sParse, 0, sizeof(sParse));
  sParse.eParseMode = PARSE_MODE_RENAME_COLUMN;
  sParse.db = db;
  sParse.nQueryLoop = 1;
  rc = sqlite3RunParser(&sParse, zSql, &zErr);
  assert( sParse.zErrMsg==0 );
  assert( rc!=SQLITE_OK || zErr==0 );
  assert( (!!sParse.pNewTable)+(!!sParse.pNewIndex)+(!!sParse.pNewTrigger)<2 );
  sParse.zErrMsg = zErr;
  if( db->mallocFailed ) rc = SQLITE_NOMEM;
  if( rc==SQLITE_OK 
   && sParse.pNewTable==0 && sParse.pNewIndex==0 && sParse.pNewTrigger==0 
  ){
    rc = SQLITE_CORRUPT_BKPT;
  }















#ifdef SQLITE_DEBUG
  /* Ensure that all mappings in the Parse.pRename list really do map to
  ** a part of the input string.  */
  assert( sqlite3Strlen30(zSql)==nSql );
  if( rc==SQLITE_OK ){
    RenameToken *pToken;
    for(pToken=sParse.pRename; pToken; pToken=pToken->pNext){
      assert( pToken->t.z>=zSql && &pToken->t.z[pToken->t.n]<=&zSql[nSql] );
    }
  }
#endif

  /* Set zQuot to point to a buffer containing a quoted copy of the 
  ** identifier zNew. If the corresponding identifier in the original 
  ** ALTER TABLE statement was quoted (bQuote==1), then set zNew to
  ** point to zQuot so that all substitutions are made using the
  ** quoted version of the new column name.  */
  if( rc==SQLITE_OK ){
    zQuot = sqlite3_mprintf("\"%w\"", zNew);
    if( zQuot==0 ){
      rc = SQLITE_NOMEM;
    }else{
      nQuot = sqlite3Strlen30(zQuot);
    }
  }
  if( bQuote ){
    zNew = zQuot;
    nNew = nQuot;
  }

  /* Find tokens that need to be replaced. */
  memset(&sWalker, 0, sizeof(Walker));
  sWalker.pParse = &sParse;
  sWalker.xExprCallback = renameColumnExprCb;
  sWalker.xSelectCallback = renameColumnSelectCb;
  sWalker.u.pRename = &sCtx;
................................................................................
    Select *pSelect = sParse.pNewTable->pSelect;
    if( pSelect ){
      sParse.rc = SQLITE_OK;
      sqlite3SelectPrep(&sParse, sParse.pNewTable->pSelect, 0);
      rc = (db->mallocFailed ? SQLITE_NOMEM : sParse.rc);
      if( rc==SQLITE_OK ){
        sqlite3WalkSelect(&sWalker, pSelect);






      }
      if( rc!=SQLITE_OK ) goto renameColumnFunc_done;
    }else{
      /* A regular table */
      int bFKOnly = sqlite3_stricmp(zTable, sParse.pNewTable->zName);
      FKey *pFKey;
      assert( sParse.pNewTable->pSelect==0 );
................................................................................
        sqlite3WalkExprList(&sWalker, pUpsert->pUpsertSet);
        sqlite3WalkExpr(&sWalker, pUpsert->pUpsertWhere);
        sqlite3WalkExpr(&sWalker, pUpsert->pUpsertTargetWhere);
      }
    }
  }

  /* At this point sCtx.pList contains a list of RenameToken objects
  ** corresponding to all tokens in the input SQL that must be replaced
  ** with the new column name. All that remains is to construct and
  ** return the edited SQL string. */
  assert( rc==SQLITE_OK );
  assert( nQuot>=nNew );
  zOut = sqlite3DbMallocZero(db, nSql + sCtx.nList*nQuot + 1);
  if( zOut ){
    int nOut = nSql;
    memcpy(zOut, zSql, nSql);
    while( sCtx.pList ){
................................................................................
    sqlite3DbFree(db, zOut);
  }else{
    rc = SQLITE_NOMEM;
  }

renameColumnFunc_done:
  if( rc!=SQLITE_OK ){
    if( sParse.zErrMsg ){
      renameColumnParseError(context, &sParse);
    }else{
      sqlite3_result_error_code(context, rc);
    }
  }

  if( sParse.pVdbe ){
    sqlite3VdbeFinalize(sParse.pVdbe);
  }
  sqlite3DeleteTable(db, sParse.pNewTable);
  if( sParse.pNewIndex ) sqlite3FreeIndex(db, sParse.pNewIndex);
  sqlite3DeleteTrigger(db, sParse.pNewTrigger);
  renameTokenFree(db, sParse.pRename);
  renameTokenFree(db, sCtx.pList);
  sqlite3DbFree(db, sParse.zErrMsg);
  sqlite3ParserReset(&sParse);
  sqlite3_free(zQuot);
}

/*
** Register built-in functions used to help implement ALTER TABLE
*/

set testprefix altercol

# If SQLITE_OMIT_ALTERTABLE is defined, omit this file.
ifcapable !altertable {
  finish_test
  return
}















foreach {tn before after} {
  1 {CREATE TABLE t1(a INTEGER, b TEXT, c BLOB)}
    {CREATE TABLE t1(a INTEGER, d TEXT, c BLOB)}

  2 {CREATE TABLE t1(a INTEGER, x TEXT, "b" BLOB)}
    {CREATE TABLE t1(a INTEGER, x TEXT, "d" BLOB)}
................................................................................
}

do_execsql_test 8.4.4 {
  ALTER TABLE b2 RENAME x TO hello;
  SELECT sql FROM sqlite_master WHERE name='xxx';
} {{CREATE VIEW xxx AS SELECT a FROM b1 UNION SELECT hello FROM b2 ORDER BY 1 COLLATE nocase}}

do_execsql_test 8.4.5 {
  CREATE VIEW zzz AS SELECT george, ringo FROM b1;
  ALTER TABLE b1 RENAME a TO aaa;
  SELECT sql FROM sqlite_master WHERE name = 'zzz'
} {{CREATE VIEW zzz AS SELECT george, ringo FROM b1}}

#-------------------------------------------------------------------------
# More triggers.
#
proc do_rename_column_test {tn old new lSchema} {

  for {set i 0} {$i < 2} {incr i} {
    # DROP all tables and views in database.
    set sql "SELECT name FROM sqlite_master WHERE type='table' ORDER BY 1"
    foreach nm [db eval $sql] { db eval "DROP TABLE $nm" }
    set sql "SELECT name FROM sqlite_master WHERE type='view' ORDER BY 1"
    foreach nm [db eval $sql] { db eval "DROP VIEW $nm" }


    set lSorted [list]
    foreach sql $lSchema { 
      execsql $sql 
      lappend lSorted [string trim $sql]
    }
    set lSorted [lsort $lSorted]

    do_execsql_test $tn.$i.1 {
      SELECT sql FROM sqlite_master WHERE sql!='' ORDER BY 1
    } $lSorted

    if {0 && $i==1} {
      db close
      sqlite3 db test.db
    }

    do_execsql_test $tn.$i.2 "ALTER TABLE t1 RENAME $old TO $new"

    do_execsql_test $tn.$i.3 {
................................................................................
    { CREATE VIRTUAL TABLE e1 USING echo(t1) }
  }
} {
  register_echo_module db
  do_rename_column_test 10.$tn $old $new $lSchema
}



























finish_test

set testprefix altercol

# If SQLITE_OMIT_ALTERTABLE is defined, omit this file.
ifcapable !altertable {
  finish_test
  return
}

# Drop all the tables and views in the 'main' database of database connect
# [db]. Sort the objects by name before dropping them.
#
proc drop_all_tables_and_views {db} {
  set SQL {
    SELECT name, type FROM sqlite_master 
    WHERE type IN ('table', 'view') AND name NOT LIKE 'sqlite_%'
    ORDER BY 1
  }
  foreach {z t} [db eval $SQL] {
    db eval "DROP $t $z"
  }
}

foreach {tn before after} {
  1 {CREATE TABLE t1(a INTEGER, b TEXT, c BLOB)}
    {CREATE TABLE t1(a INTEGER, d TEXT, c BLOB)}

  2 {CREATE TABLE t1(a INTEGER, x TEXT, "b" BLOB)}
    {CREATE TABLE t1(a INTEGER, x TEXT, "d" BLOB)}
................................................................................
}

do_execsql_test 8.4.4 {
  ALTER TABLE b2 RENAME x TO hello;
  SELECT sql FROM sqlite_master WHERE name='xxx';
} {{CREATE VIEW xxx AS SELECT a FROM b1 UNION SELECT hello FROM b2 ORDER BY 1 COLLATE nocase}}

do_catchsql_test 8.4.5 {
  CREATE VIEW zzz AS SELECT george, ringo FROM b1;
  ALTER TABLE b1 RENAME a TO aaa;
} {1 {error processing view zzz: no such column: george}}


#-------------------------------------------------------------------------
# More triggers.
#
proc do_rename_column_test {tn old new lSchema} {

  for {set i 0} {$i < 2} {incr i} {





    drop_all_tables_and_views db

    set lSorted [list]
    foreach sql $lSchema { 
      execsql $sql 
      lappend lSorted [string trim $sql]
    }
    set lSorted [lsort $lSorted]

    do_execsql_test $tn.$i.1 {
      SELECT sql FROM sqlite_master WHERE sql!='' ORDER BY 1
    } $lSorted

    if {$i==1} {
      db close
      sqlite3 db test.db
    }

    do_execsql_test $tn.$i.2 "ALTER TABLE t1 RENAME $old TO $new"

    do_execsql_test $tn.$i.3 {
................................................................................
    { CREATE VIRTUAL TABLE e1 USING echo(t1) }
  }
} {
  register_echo_module db
  do_rename_column_test 10.$tn $old $new $lSchema
}

#--------------------------------------------------------------------------
# Test that if a view or trigger refers to a virtual table for which the
# module is not available, RENAME COLUMN cannot proceed.
#
reset_db
register_echo_module db
do_execsql_test 11.0 {
  CREATE TABLE x1(a, b, c);
  CREATE VIRTUAL TABLE e1 USING echo(x1);
}
db close
sqlite3 db test.db

do_execsql_test 11.1 {
  ALTER TABLE x1 RENAME b TO bbb;
  SELECT sql FROM sqlite_master;
} { {CREATE TABLE x1(a, bbb, c)} {CREATE VIRTUAL TABLE e1 USING echo(x1)} }

do_execsql_test 11.2 {
  CREATE VIEW v1 AS SELECT e1.*, x1.c FROM e1, x1;
}

do_catchsql_test 11.3 {
  ALTER TABLE x1 RENAME c TO ccc;
} {1 {error processing view v1: no such module: echo}}

finish_test