** 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.
**
*************************************************************************
** $Id: btree.c,v 1.154 2004/05/31 10:01:35 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
................................................................................
    releasePage(pCur->pPage);
    sqliteFree(pCur);
  }
  unlockBtreeIfUnused(pBt);
  return rc;
}


/*
** Change the value of the comparison function used by a cursor.
*/
void sqlite3BtreeSetCompare(
  BtCursor *pCur,     /* The cursor to whose comparison function is changed */
  int(*xCmp)(void*,int,const void*,int,const void*), /* New comparison func */
  void *pArg          /* First argument to xCmp() */
){
  pCur->xCompare = xCmp ? xCmp : dfltCompare;
  pCur->pArg = pArg;
}


/*
** Close a cursor.  The read lock on the database file is released
** when the last cursor is closed.
*/
int sqlite3BtreeCloseCursor(BtCursor *pCur){
  Btree *pBt = pCur->pBt;

** 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.
**
*************************************************************************
** $Id: btree.c,v 1.155 2004/06/02 01:22:02 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.
................................................................................
    releasePage(pCur->pPage);
    sqliteFree(pCur);
  }
  unlockBtreeIfUnused(pBt);
  return rc;
}

#if 0  /* Not Used */
/*
** Change the value of the comparison function used by a cursor.
*/
void sqlite3BtreeSetCompare(
  BtCursor *pCur,     /* The cursor to whose comparison function is changed */
  int(*xCmp)(void*,int,const void*,int,const void*), /* New comparison func */
  void *pArg          /* First argument to xCmp() */
){
  pCur->xCompare = xCmp ? xCmp : dfltCompare;
  pCur->pArg = pArg;
}
#endif

/*
** Close a cursor.  The read lock on the database file is released
** when the last cursor is closed.
*/
int sqlite3BtreeCloseCursor(BtCursor *pCur){
  Btree *pBt = pCur->pBt;

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.
**
** @(#) $Id: sqlite.h.in,v 1.90 2004/06/02 00:41:09 drh Exp $
*/
#ifndef _SQLITE_H_
#define _SQLITE_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
/*
** The version string is also compiled into the library so that a program
** can check to make sure that the lib*.a file and the *.h file are from
** the same version.
*/
extern const char sqlite3_version[];

/*
** The SQLITE_UTF8 macro is defined if the library expects to see
** UTF-8 encoded data.  The SQLITE_ISO8859 macro is defined if the
** iso8859 encoded should be used.
*/
#define SQLITE_--ENCODING-- 1

/*
** The following constant holds one of two strings, "UTF-8" or "iso8859",
** depending on which character encoding the SQLite library expects to
** see.  The character encoding makes a difference for the LIKE and GLOB
** operators and for the LENGTH() and SUBSTR() functions.
*/
extern const char sqlite3_encoding[];

/*
** Each open sqlite database is represented by an instance of the
** following opaque structure.
*/
typedef struct sqlite sqlite;
typedef struct sqlite sqlite3;

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the SQLite library
** presents to client programs.
**
** @(#) $Id: sqlite.h.in,v 1.91 2004/06/02 01:22:02 drh Exp $
*/
#ifndef _SQLITE_H_
#define _SQLITE_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
/*
** The version string is also compiled into the library so that a program
** can check to make sure that the lib*.a file and the *.h file are from
** the same version.
*/
extern const char sqlite3_version[];
















/*
** Each open sqlite database is represented by an instance of the
** following opaque structure.
*/
typedef struct sqlite sqlite;
typedef struct sqlite sqlite3;

**
** 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 1.354 2004/05/31 23:56:43 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
*/
static Sorter *Merge(Sorter *pLeft, Sorter *pRight, KeyInfo *pKeyInfo){
  Sorter sHead;
  Sorter *pTail;
  pTail = &sHead;
  pTail->pNext = 0;
  while( pLeft && pRight ){
    int c = sqlite3VdbeKeyCompare(pKeyInfo, pLeft->nKey, pLeft->zKey,
                                  pRight->nKey, pRight->zKey);
    /* int c = sqlite3SortCompare(pLeft->zKey, pRight->zKey); */
    if( c<=0 ){
      pTail->pNext = pLeft;
      pLeft = pLeft->pNext;
    }else{
      pTail->pNext = pRight;
      pRight = pRight->pNext;
    }
................................................................................
**  'n'            NUMERIC
**  'i'            INTEGER
**  't'            TEXT
**  'o'            NONE
**
** If P3 is NULL then all index fields have the affinity NONE.
*/






























case OP_MakeKey:
case OP_MakeIdxKey:
case OP_MakeRecord: {
  /* Assuming the record contains N fields, the record format looks
  ** like this:
  **
  ** --------------------------------------------------------------------------
  ** | header-siz | type 0 | type 1 | ... | type N-1 | data0 | ... | data N-1 | 
  ** --------------------------------------------------------------------------
  **
  ** Data(0) is taken from the lowest element of the stack and data(N-1) is
  ** the top of the stack.
  **
  ** Each type field is a varint representing the serial type of the 
  ** corresponding data element (see sqlite3VdbeSerialType()). The
  ** num-fields field is also a varint storing N.
  ** 
  ** TODO: Even when the record is short enough for Mem::zShort, this opcode
  **   allocates it dynamically.
  */
  int nField = pOp->p1;
  unsigned char *zNewRecord;
  unsigned char *zCsr;
  char *zAffinity;
  Mem *pRec;
  Mem *pRowid;
................................................................................
  assert( i>=0 );
  if( expandCursorArraySize(p, i) ) goto no_mem;
  pCur = p->apCsr[i];
  sqlite3VdbeCleanupCursor(pCur);
  pCur->nullRow = 1;
  if( pX==0 ) break;
  do{
    /* When opening cursors, always supply the comparison function
    ** sqlite3VdbeKeyCompare(). If the table being opened is of type
    ** INTKEY, the btree layer won't call the comparison function anyway.
    */
    rc = sqlite3BtreeCursor(pX, p2, wrFlag,
             sqlite3VdbeKeyCompare, pOp->p3,
             &pCur->pCursor);
    pCur->pKeyInfo = (KeyInfo*)pOp->p3;
    if( pCur->pKeyInfo ){
      pCur->pIncrKey = &pCur->pKeyInfo->incrKey;
      pCur->pKeyInfo->enc = p->db->enc;
    }else{
      pCur->pIncrKey = &pCur->bogusIncrKey;
................................................................................
    */
    if( pOp->p3 ){
      int pgno;
      assert( pOp->p3type==P3_KEYINFO );
      rc = sqlite3BtreeCreateTable(pCx->pBt, &pgno, BTREE_ZERODATA); 
      if( rc==SQLITE_OK ){
        assert( pgno==MASTER_ROOT+1 );
        rc = sqlite3BtreeCursor(pCx->pBt, pgno, 1, sqlite3VdbeKeyCompare,
            pOp->p3, &pCx->pCursor);
        pCx->pKeyInfo = (KeyInfo*)pOp->p3;
        pCx->pKeyInfo->enc = p->db->enc;
        pCx->pIncrKey = &pCx->pKeyInfo->incrKey;
      }
    }else{
      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, 0, &pCx->pCursor);
................................................................................

/* Opcode: KeyAsData P1 P2 *
**
** Turn the key-as-data mode for cursor P1 either on (if P2==1) or
** off (if P2==0).  In key-as-data mode, the OP_Column opcode pulls
** data off of the key rather than the data.  This is used for
** processing compound selects.
**
** This opcode also instructs the cursor that the keys used will be
** serialized in the record format usually used for table data, not
** the usual index key format.
*/
case OP_KeyAsData: {
  int i = pOp->p1;
  Cursor *pC;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  pC->keyAsData = pOp->p2;
  sqlite3BtreeSetCompare(pC->pCursor, sqlite3VdbeRowCompare, pC->pKeyInfo);
  break;
}

/* Opcode: RowData P1 * *
**
** Push onto the stack the complete row data for cursor P1.
** There is no interpretation of the data.  It is just copied

**
** 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 1.355 2004/06/02 01:22:02 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
................................................................................
*/
static Sorter *Merge(Sorter *pLeft, Sorter *pRight, KeyInfo *pKeyInfo){
  Sorter sHead;
  Sorter *pTail;
  pTail = &sHead;
  pTail->pNext = 0;
  while( pLeft && pRight ){
    int c = sqlite3VdbeRecordCompare(pKeyInfo, pLeft->nKey, pLeft->zKey,
                                     pRight->nKey, pRight->zKey);

    if( c<=0 ){
      pTail->pNext = pLeft;
      pLeft = pLeft->pNext;
    }else{
      pTail->pNext = pRight;
      pRight = pRight->pNext;
    }
................................................................................
**  'n'            NUMERIC
**  'i'            INTEGER
**  't'            TEXT
**  'o'            NONE
**
** If P3 is NULL then all index fields have the affinity NONE.
*/
/* Opcode MakeRecord P1 P2 P3
**
** Convert the top abs(P1) entries of the stack into a single entry
** suitable for use as a data record in a database table or as a key
** in an index.  The details of the format are irrelavant as long as
** the OP_Column opcode can decode the record later and as long as the
** sqlite3VdbeRecordCompare function will correctly compare two encoded
** records.  Refer to source code comments for the details of the record
** format.
**
** The original stack entries are popped from the stack if P1>0 but
** remain on the stack if P1<0.
**
** If P2 is not zero and one or more of the entries are NULL, then jump
** to P2.  This feature can be used to skip a uniqueness test on indices.
**
** P3 may be a string that is P1 characters long.  The nth character of the
** string indicates the column affinity that should be used for the nth
** field of the index key (i.e. the first character of P3 corresponds to the
** lowest element on the stack).
**
**  Character      Column affinity
**  ------------------------------
**  'n'            NUMERIC
**  'i'            INTEGER
**  't'            TEXT
**  'o'            NONE
**
** If P3 is NULL then all index fields have the affinity NONE.
*/
case OP_MakeKey:
case OP_MakeIdxKey:
case OP_MakeRecord: {
  /* Assuming the record contains N fields, the record format looks
  ** like this:
  **
  ** ------------------------------------------------------------------------
  ** | hdr-size | type 0 | type 1 | ... | type N-1 | data0 | ... | data N-1 | 
  ** ------------------------------------------------------------------------
  **
  ** Data(0) is taken from the lowest element of the stack and data(N-1) is
  ** the top of the stack.
  **
  ** Each type field is a varint representing the serial type of the 
  ** corresponding data element (see sqlite3VdbeSerialType()). The
  ** hdr-size field is also a varint which is the offset from the beginning
  ** of the record to data0.


  */
  int nField = pOp->p1;
  unsigned char *zNewRecord;
  unsigned char *zCsr;
  char *zAffinity;
  Mem *pRec;
  Mem *pRowid;
................................................................................
  assert( i>=0 );
  if( expandCursorArraySize(p, i) ) goto no_mem;
  pCur = p->apCsr[i];
  sqlite3VdbeCleanupCursor(pCur);
  pCur->nullRow = 1;
  if( pX==0 ) break;
  do{
    /* We always provide a key comparison function.  If the table being
    ** opened is of type INTKEY, the comparision function will be ignored. */


    rc = sqlite3BtreeCursor(pX, p2, wrFlag,
             sqlite3VdbeRecordCompare, pOp->p3,
             &pCur->pCursor);
    pCur->pKeyInfo = (KeyInfo*)pOp->p3;
    if( pCur->pKeyInfo ){
      pCur->pIncrKey = &pCur->pKeyInfo->incrKey;
      pCur->pKeyInfo->enc = p->db->enc;
    }else{
      pCur->pIncrKey = &pCur->bogusIncrKey;
................................................................................
    */
    if( pOp->p3 ){
      int pgno;
      assert( pOp->p3type==P3_KEYINFO );
      rc = sqlite3BtreeCreateTable(pCx->pBt, &pgno, BTREE_ZERODATA); 
      if( rc==SQLITE_OK ){
        assert( pgno==MASTER_ROOT+1 );
        rc = sqlite3BtreeCursor(pCx->pBt, pgno, 1, sqlite3VdbeRecordCompare,
            pOp->p3, &pCx->pCursor);
        pCx->pKeyInfo = (KeyInfo*)pOp->p3;
        pCx->pKeyInfo->enc = p->db->enc;
        pCx->pIncrKey = &pCx->pKeyInfo->incrKey;
      }
    }else{
      rc = sqlite3BtreeCursor(pCx->pBt, MASTER_ROOT, 1, 0, 0, &pCx->pCursor);
................................................................................

/* Opcode: KeyAsData P1 P2 *
**
** Turn the key-as-data mode for cursor P1 either on (if P2==1) or
** off (if P2==0).  In key-as-data mode, the OP_Column opcode pulls
** data off of the key rather than the data.  This is used for
** processing compound selects.




*/
case OP_KeyAsData: {
  int i = pOp->p1;
  Cursor *pC;
  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  pC->keyAsData = pOp->p2;

  break;
}

/* Opcode: RowData P1 * *
**
** Push onto the stack the complete row data for cursor P1.
** There is no interpretation of the data.  It is just copied

int sqlite3VdbeSerialPut(unsigned char*, Mem*);
int sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);
int sqlite3VdbeIdxRowid(BtCursor *, i64 *);
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
int sqlite3VdbeKeyCompare(void*,int,const void*,int, const void*);
int sqlite3VdbeRowCompare(void*,int,const void*,int, const void*);
int sqlite3VdbeIdxRowidLen(int,const u8*);
int sqlite3VdbeExec(Vdbe*);
int sqlite3VdbeList(Vdbe*);
int sqlite3VdbeChangeEncoding(Mem *, int);
int sqlite3VdbeMemCopy(Mem*, const Mem*);
int sqlite3VdbeMemNulTerminate(Mem*);
int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, int);

int sqlite3VdbeSerialPut(unsigned char*, Mem*);
int sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);

int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);
int sqlite3VdbeIdxRowid(BtCursor *, i64 *);
int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
int sqlite3VdbeRecordCompare(void*,int,const void*,int, const void*);

int sqlite3VdbeIdxRowidLen(int,const u8*);
int sqlite3VdbeExec(Vdbe*);
int sqlite3VdbeList(Vdbe*);
int sqlite3VdbeChangeEncoding(Mem *, int);
int sqlite3VdbeMemCopy(Mem*, const Mem*);
int sqlite3VdbeMemNulTerminate(Mem*);
int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, int);

      pMem->flags = MEM_Blob | MEM_Ephem;
    }
  }
  return len;
}

/*
** The following is the comparison function for (non-integer)
** keys in the btrees.  This function returns negative, zero, or
** positive if the first key is less than, equal to, or greater than
** the second.
**
** This function assumes that each key consists of one or more type/blob
** pairs, encoded using the sqlite3VdbeSerialXXX() functions above. 
**
** Following the type/blob pairs, each key may have a single 0x00 byte
** followed by a varint. A key may only have this traling 0x00/varint
** pair if it has at least as many type/blob pairs as the key it is being
** compared to.
*/
int sqlite3VdbeKeyCompare(
  void *userData,
  int nKey1, const void *pKey1, 
  int nKey2, const void *pKey2
){
  return sqlite3VdbeRowCompare(userData,nKey1,pKey1,nKey2,pKey2);
}

/*
** This function compares the two table row records specified by 
** {nKey1, pKey1} and {nKey2, pKey2}, returning a negative, zero
** or positive integer if {nKey1, pKey1} is less than, equal to or 
** greater than {nKey2, pKey2}.
**
** This function is pretty inefficient and will probably be replaced
** by something else in the near future. It is currently required
** by compound SELECT operators. 

*/
int sqlite3VdbeRowCompare(
  void *userData,
  int nKey1, const void *pKey1, 
  int nKey2, const void *pKey2
){
  KeyInfo *pKeyInfo = (KeyInfo*)userData;
  u32 d1, d2;          /* Offset into aKey[] of next data element */
  u32 idx1, idx2;      /* Offset into aKey[] of next header element */
................................................................................
    rc = -rc;
  }

  return rc;
}

/*
** The argument is an index key that contains the ROWID at the end.
** Return the length of the rowid.


*/
int sqlite3VdbeIdxRowidLen(int nKey, const u8 *aKey){
  u32 szHdr;        /* Size of the header */
  u32 typeRowid;    /* Serial type of the rowid */

  sqlite3GetVarint32(aKey, &szHdr);
  sqlite3GetVarint32(&aKey[szHdr-1], &typeRowid);
  return sqlite3VdbeSerialTypeLen(typeRowid);
}
  

/*
** pCur points at an index entry. Read the rowid (varint occuring at
** the end of the entry and store it in *rowid. Return SQLITE_OK if
** everything works, or an error code otherwise.
*/
int sqlite3VdbeIdxRowid(BtCursor *pCur, i64 *rowid){
  u64 nCellKey;
  int rc;
  u32 szHdr;        /* Size of the header */
  u32 typeRowid;    /* Serial type of the rowid */
  u32 lenRowid;     /* Size of the rowid */
................................................................................
    return SQLITE_OK;
  }
  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, nCellKey, 1, &m);
  if( rc ){
    return rc;
  }
  lenRowid = sqlite3VdbeIdxRowidLen(m.n, m.z);
  *res = sqlite3VdbeKeyCompare(pC->pKeyInfo, m.n-lenRowid, m.z, nKey, pKey);
  if( m.flags & MEM_Dyn ){
    sqliteFree(m.z);
  }
  return SQLITE_OK;
}

      pMem->flags = MEM_Blob | MEM_Ephem;
    }
  }
  return len;
}

/*






















** This function compares the two table rows or index records specified by 
** {nKey1, pKey1} and {nKey2, pKey2}, returning a negative, zero
** or positive integer if {nKey1, pKey1} is less than, equal to or 
** greater than {nKey2, pKey2}.  Both Key1 and Key2 must be byte strings




** composed by the OP_MakeRecord opcode of the VDBE.
*/
int sqlite3VdbeRecordCompare(
  void *userData,
  int nKey1, const void *pKey1, 
  int nKey2, const void *pKey2
){
  KeyInfo *pKeyInfo = (KeyInfo*)userData;
  u32 d1, d2;          /* Offset into aKey[] of next data element */
  u32 idx1, idx2;      /* Offset into aKey[] of next header element */
................................................................................
    rc = -rc;
  }

  return rc;
}

/*
** The argument is an index entry composed using the OP_MakeRecord opcode.
** The last entry in this record should be an integer (specifically
** an integer rowid).  This routine returns the number of bytes in
** that integer.
*/
int sqlite3VdbeIdxRowidLen(int nKey, const u8 *aKey){
  u32 szHdr;        /* Size of the header */
  u32 typeRowid;    /* Serial type of the rowid */

  sqlite3GetVarint32(aKey, &szHdr);
  sqlite3GetVarint32(&aKey[szHdr-1], &typeRowid);
  return sqlite3VdbeSerialTypeLen(typeRowid);
}
  

/*
** pCur points at an index entry created using the OP_MakeRecord opcode.
** Read the rowid (the last field in the record) and store it in *rowid.
** Return SQLITE_OK if everything works, or an error code otherwise.
*/
int sqlite3VdbeIdxRowid(BtCursor *pCur, i64 *rowid){
  u64 nCellKey;
  int rc;
  u32 szHdr;        /* Size of the header */
  u32 typeRowid;    /* Serial type of the rowid */
  u32 lenRowid;     /* Size of the rowid */
................................................................................
    return SQLITE_OK;
  }
  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, nCellKey, 1, &m);
  if( rc ){
    return rc;
  }
  lenRowid = sqlite3VdbeIdxRowidLen(m.n, m.z);
  *res = sqlite3VdbeRecordCompare(pC->pKeyInfo, m.n-lenRowid, m.z, nKey, pKey);
  if( m.flags & MEM_Dyn ){
    sqliteFree(m.z);
  }
  return SQLITE_OK;
}