SQLite

** using the DECLARE...CURSOR command and deleted using CLOSE.  A
** B-tree cursor is an abstraction of the b-tree layer.  See the btree.c
** module for additional information.  There is also a VDBE-cursor that
** is used by the VDBE module.  Even though all these objects are called
** cursors, they are really very different things.  It is worth your while
** to fully understand the difference.
**
** @(#) $Id: cursor.c,v 1.2 2004/11/23 01:47:30 drh Exp $
*/
#ifndef SQLITE_OMIT_CURSOR
#include "sqliteInt.h"
#include "vdbeInt.h"

/*
** Delete a cursor object.

  }
  if( i>=db->nSqlCursor ){
    db->apSqlCursor = sqliteRealloc(db->apSqlCursor, (i+1)*sizeof(pNew));
    db->nSqlCursor = i+1;
  }
  db->apSqlCursor[i] = pNew = sqliteMallocRaw( sizeof(*pNew) + pName->n + 1 );
  if( pNew==0 ) goto end_create_cursor;
  pNew->idx = i;
  pNew->zName = (char*)&pNew[1];
  memcpy(pNew->zName, pName->z, pName->n);
  pNew->zName[pName->n] = 0;
  pNew->pSelect = sqlite3SelectDup(pSelect);
  pNew->nPtr = 2;
  pNew->aPtr = sqliteMalloc( sizeof(Mem)*2 );
  for(i=0; i<2; i++){
    pNew->aPtr[i].flags = MEM_Null;
  }

end_create_cursor:
  sqlite3SelectDelete(pSelect);
}

/*
** The parser calls this routine in response to a CLOSE command.  Delete

    return;
  }
  assert( p->idx>=0 && p->idx<db->nSqlCursor );
  assert( db->apSqlCursor[p->idx]==p );
  db->apSqlCursor[p->idx] = 0;
  sqlite3CursorDelete(p);
}

/*
** Reverse the direction the ORDER BY clause on the SELECT statement.
*/
static void reverseSortOrder(Select *p){
  if( p->pOrderBy==0 ){
    /* If there no ORDER BY clause, add a new one that is "rowid DESC" */
    static const Token rowid = { "ROWID", 0, 5 };
    Expr *pExpr = sqlite3Expr(TK_ID, 0, 0, &rowid);
    ExprList *pList = sqlite3ExprListAppend(0, pExpr, 0);
    if( pList )  pList->a[0].sortOrder = SQLITE_SO_DESC;
    p->pOrderBy = pList;
  }else{
    int i;
    ExprList *pList = p->pOrderBy;
    for(i=0; i<pList->nExpr; i++){
      pList->a[i].sortOrder = !pList->a[i].sortOrder;
    }
  }
}

/*
** The parser calls this routine when it sees a complete FETCH statement.
** This routine generates code to implement the FETCH.
**
** Information about the direction of the FETCH has already been inserted
** into the pParse structure by parser rules.  The arguments specify the

    return;
  }
  sFetch.pCursor = p;
  pCopy = sqlite3SelectDup(p->pSelect);
  pCopy->pFetch = &sFetch;
  switch( pParse->fetchDir ){
    case TK_FIRST: {
      sFetch.isBackwards = 0;
      sFetch.doRewind = 1;
      pCopy->nLimit = pParse->dirArg1;
      pCopy->nOffset = 0;
      break;
    }
    case TK_LAST: {
      reverseSortOrder(pCopy);
      sFetch.isBackwards = 1;
      sFetch.doRewind = 1;
      pCopy->nLimit = pParse->dirArg1;
      pCopy->nOffset = 0;
      break;
    }
    case TK_NEXT: {
      sFetch.isBackwards = 0;
      sFetch.doRewind = 0;
      pCopy->nLimit = pParse->dirArg1;
      pCopy->nOffset = 0;
      break;
    }
    case TK_PRIOR: {
      reverseSortOrder(pCopy);
      sFetch.isBackwards = 1;
      sFetch.doRewind = 0;
      pCopy->nLimit = pParse->dirArg1;
      pCopy->nOffset = 0;
      break;
    }
    case TK_ABSOLUTE: {
      sFetch.isBackwards = 0;
      sFetch.doRewind = 1;
      pCopy->nLimit = pParse->dirArg1;
      pCopy->nOffset = pParse->dirArg2;
      break;
    }
    default: {
      assert( pParse->fetchDir==TK_RELATIVE );
      if( pParse->dirArg2>=0 ){
        /* The index parameter is positive.  Move forward from the current
        ** location */
        sFetch.isBackwards = 0;
        sFetch.doRewind = 0;
        pCopy->nLimit = pParse->dirArg1;
        pCopy->nOffset = pParse->dirArg2;
      }else{
        /* The index is negative.  We have to code two separate SELECTs.
        ** The first one seeks to the no position and the second one does
        ** the query.
        */
        Select *pSeek = sqlite3SelectDup(pCopy);
        reverseSortOrder(pSeek);
        sFetch.isBackwards = 1;
        sFetch.doRewind = 0;
        pSeek->nLimit = pParse->dirArg2;
        pSeek->pFetch = &sFetch;
        sqlite3Select(pParse, pSeek, SRT_Discard, 0, 0, 0, 0, 0);
        sFetch.isBackwards = 0;
        sFetch.doRewind = 0;
        pCopy->nLimit = pParse->dirArg1;
        pCopy->nOffset = 0;
      }
      break;
    }
  }
  sqlite3Select(pParse, pCopy, SRT_Callback, 0, 0, 0, 0, 0);

end_fetch:
  sqlite3IdListDelete(pInto);
}

#endif /* SQLITE_OMIT_CURSOR */

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle DELETE FROM statements.
**
** $Id: delete.c,v 1.91 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.

      if( sqlite3CheckIndexCollSeq(pParse, pIdx) ){
        goto delete_from_cleanup;
      }
    }

    /* Begin the database scan
    */
    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0, 0);
    if( pWInfo==0 ) goto delete_from_cleanup;

    /* Remember the key of every item to be deleted.
    */
    sqlite3VdbeAddOp(v, OP_ListWrite, 0, 0);
    if( db->flags & SQLITE_CountRows ){
      sqlite3VdbeAddOp(v, OP_AddImm, 1, 0);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.174 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** Return the 'affinity' of the expression pExpr if any.
**

}

/*
** Construct a new expression node and return a pointer to it.  Memory
** for this node is obtained from sqliteMalloc().  The calling function
** is responsible for making sure the node eventually gets freed.
*/
Expr *sqlite3Expr(int op, Expr *pLeft, Expr *pRight, const Token *pToken){
  Expr *pNew;
  pNew = sqliteMalloc( sizeof(Expr) );
  if( pNew==0 ){
    /* When malloc fails, we leak memory from pLeft and pRight */
    return 0;
  }
  pNew->op = op;

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.217 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"


/*
** Allocate a new Select structure and return a pointer to that
** structure.

    openTempIndex(pParse, p, distinct, 0);
  }else{
    distinct = -1;
  }

  /* Begin the database scan
  */







  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0,
                             pGroupBy ? 0 : &pOrderBy, p->pFetch);

  if( pWInfo==0 ) goto select_end;

  /* Use the standard inner loop if we are not dealing with
  ** aggregates
  */
  if( !isAgg ){
    if( selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, eDest,

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.344 2004/11/23 01:47:30 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks

void *sqlite3TextToPtr(const char*);
void sqlite3SetString(char **, const char *, ...);
void sqlite3ErrorMsg(Parse*, const char*, ...);
void sqlite3Dequote(char*);
int sqlite3KeywordCode(const char*, int);
int sqlite3RunParser(Parse*, const char*, char **);
void sqlite3FinishCoding(Parse*);
Expr *sqlite3Expr(int, Expr*, Expr*, const Token*);
Expr *sqlite3RegisterExpr(Parse*,Token*);
Expr *sqlite3ExprAnd(Expr*, Expr*);
void sqlite3ExprSpan(Expr*,Token*,Token*);
Expr *sqlite3ExprFunction(ExprList*, Token*);
void sqlite3ExprAssignVarNumber(Parse*, Expr*);
void sqlite3ExprDelete(Expr*);
ExprList *sqlite3ExprListAppend(ExprList*,Expr*,Token*);

void sqlite3SelectUnbind(Select*);
Table *sqlite3SrcListLookup(Parse*, SrcList*);
int sqlite3IsReadOnly(Parse*, Table*, int);
void sqlite3OpenTableForReading(Vdbe*, int iCur, Table*);
void sqlite3OpenTable(Vdbe*, int iCur, Table*, int);
void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, int, ExprList**, Fetch*);
void sqlite3WhereEnd(WhereInfo*);
void sqlite3ExprCode(Parse*, Expr*);
int sqlite3ExprCodeExprList(Parse*, ExprList*);
void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
void sqlite3NextedParse(Parse*, const char*, ...);
Table *sqlite3FindTable(sqlite3*,const char*, const char*);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.97 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
**
**   UPDATE OR IGNORE table_wxyz SET a=b, c=d WHERE e<5 AND f NOT NULL;

    pView = sqlite3SelectDup(pTab->pSelect);
    sqlite3Select(pParse, pView, SRT_TempTable, iCur, 0, 0, 0, 0);
    sqlite3SelectDelete(pView);
  }

  /* Begin the database scan
  */
  pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 1, 0, 0);
  if( pWInfo==0 ) goto update_cleanup;

  /* Remember the index of every item to be updated.
  */
  sqlite3VdbeAddOp(v, OP_ListWrite, 0, 0);

  /* End the database scan loop.

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.431 2004/11/23 01:47:30 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

*/
case OP_Vacuum: {
  if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse; 
  rc = sqlite3RunVacuum(&p->zErrMsg, db);
  if( sqlite3SafetyOn(db) ) goto abort_due_to_misuse;
  break;
}

#ifndef SQLITE_OMIT_CURSOR
/* Opcode: CursorStore P1 P2 *
**
** The implementation of SQL cursors (not to be confused with VDBE cursors
** or B-tree cursors) stores information in the SQLite database connection
** structure (the sqlite3* pointer) that identifies the row
** in a table that an SQL cursor is pointing to.  This opcode is
** used to store that information.  P1 is an index of an SQL cursor.
** P2 is the index of a memory slot within that SQL cursor.  This opcode
** pops the top of the stack and stores it in the SQL cursor.
*/
case OP_CursorStore: {
  SqlCursor *pCursor;
  assert( pTos>=p->aStack );
  assert( pOp->p1>=0 && pOp->p1<db->nSqlCursor );
  pCursor = db->apSqlCursor[pOp->p1];
  assert( pCursor!=0 );
  assert( pOp->p2>=0 && pOp->p2<2 );  
  rc = sqlite3VdbeMemMove(&pCursor->aPtr[pOp->p1], pTos);
  pTos--;
  break;
}

/* Opcode: CursorLoad P1 P2 *
**
** The implementation of SQL cursors (not to be confused with VDBE cursors
** or B-tree cursors) stores information in the SQLite database connection
** structure (the sqlite3* pointer) that effectively records the current
** location in a table that an SQL cursor is pointing to.  This opcode is
** used to recover that information.  P1 is an index of an SQL cursor.
** P2 is the index of a memory slot within that SQL cursor.  This opcode
** pushes a new value onto the stack which is a copy of the information
** obtained from entry P2 of cursor P1.
*/
case OP_CursorLoad: {
  SqlCursor *pCursor;
  int i = pOp->p1;
  assert( pTos>=p->aStack );
  assert( pOp->p1>=0 && pOp->p1<db->nSqlCursor );
  pCursor = db->apSqlCursor[pOp->p1];
  assert( pCursor!=0 );
  assert( pOp->p2>=0 && pOp->p2<2 );  
  pTos++;
  sqlite3VdbeMemShallowCopy(pTos, &pCursor->aPtr[i], MEM_Ephem);
  break;
}
#endif /* SQLITE_OMIT_CURSOR */



/* An other opcode is illegal...
*/
default: {
  sqlite3_snprintf(sizeof(zBuf),zBuf,"%d",pOp->opcode);
  sqlite3SetString(&p->zErrMsg, "unknown opcode ", zBuf, (char*)0);
  rc = SQLITE_INTERNAL;

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** $Id: where.c,v 1.120 2004/11/23 01:47:31 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.

** scan is correct for the ORDER BY clause, then that index is used and
** *ppOrderBy is set to NULL.  This is an optimization that prevents an
** unnecessary sort of the result set if an index appropriate for the
** ORDER BY clause already exists.
**
** If the where clause loops cannot be arranged to provide the correct
** output order, then the *ppOrderBy is unchanged.




*/
WhereInfo *sqlite3WhereBegin(
  Parse *pParse,        /* The parser context */
  SrcList *pTabList,    /* A list of all tables to be scanned */
  Expr *pWhere,         /* The WHERE clause */
  int pushKey,          /* If TRUE, leave the table key on the stack */
  ExprList **ppOrderBy, /* An ORDER BY clause, or NULL */
  Fetch *pFetch         /* Initial location of cursors.  NULL otherwise */
){
  int i;                     /* Loop counter */
  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
  int brk, cont = 0;         /* Addresses used during code generation */
  int nExpr;           /* Number of subexpressions in the WHERE clause */
  int loopMask;        /* One bit set for each outer loop */
  int haveKey = 0;     /* True if KEY is on the stack */
  ExprInfo *pTerm;     /* A single term in the WHERE clause; ptr to aExpr[] */
  ExprMaskSet maskSet; /* The expression mask set */
  int iDirectEq[32];   /* Term of the form ROWID==X for the N-th table */
  int iDirectLt[32];   /* Term of the form ROWID<X or ROWID<=X */
  int iDirectGt[32];   /* Term of the form ROWID>X or ROWID>=X */
  ExprInfo aExpr[101]; /* The WHERE clause is divided into these terms */

  /* pushKey is only allowed if there is a single table (as in an INSERT or
  ** UPDATE statement)
  */
  assert( pushKey==0 || pTabList->nSrc==1 );

  /*
  */

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.  If the aExpr[]
  ** array fills up, the last entry might point to an expression which
  ** contains additional unfactored AND operators.
  */
  initMaskSet(&maskSet);

# 2004 November 22
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#*************************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is DECLARE...CURSOR functionality
#
# $Id: cursor.test,v 1.2 2004/11/23 01:47:31 drh Exp $
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# If SQLITE_OMIT_CURSOR is defined, omit this file.
ifcapable {!cursor} {