SQLite

/*
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.70 2002/08/13 00:01:17 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.

  int nDiv;                    /* Number of cells in apDiv[] */
  int i, j, k;                 /* Loop counters */
  int idx;                     /* Index of pPage in pParent->apCell[] */
  int nxDiv;                   /* Next divider slot in pParent->apCell[] */
  int rc;                      /* The return code */
  int iCur;                    /* apCell[iCur] is the cell of the cursor */
  MemPage *pOldCurPage;        /* The cursor originally points to this page */
  int totalSize;               /* Total bytes for all cells */
  int subtotal;                /* Subtotal of bytes in cells on one page */
  int cntNew[4];               /* Index in apCell[] of cell after i-th page */
  int szNew[4];                /* Combined size of cells place on i-th page */
  MemPage *extraUnref = 0;     /* A page that needs to be unref-ed */
  Pgno pgno, swabPgno;         /* Page number */
  Cell *apCell[MX_CELL*3+5];   /* All cells from pages being balanceed */
  int szCell[MX_CELL*3+5];     /* Local size of all cells */

  ** size of all cells on the i-th page and cntNew[] which is the index
  ** in apCell[] of the cell that divides path i from path i+1.  
  ** cntNew[k] should equal nCell.
  **
  ** This little patch of code is critical for keeping the tree
  ** balanced. 
  */
  totalSize = 0;
  for(i=0; i<nCell; i++){
    totalSize += szCell[i];
  }
  for(subtotal=k=i=0; i<nCell; i++){
    subtotal += szCell[i];
    if( subtotal > USABLE_SPACE ){
      szNew[k] = subtotal - szCell[i];
      cntNew[k] = i;
      subtotal = 0;
      k++;

  unsigned long longvalue;  /* Value for integer types */
  double realvalue;         /* Value for real types */
  et_info *infop;           /* Pointer to the appropriate info structure */
  char buf[etBUFSIZE];      /* Conversion buffer */
  char prefix;              /* Prefix character.  "+" or "-" or " " or '\0'. */
  int  errorflag = 0;       /* True if an error is encountered */
  enum et_type xtype;       /* Conversion paradigm */
  char *zMem;               /* String to be freed */
  char *zExtra;             /* Extra memory used for etTCLESCAPE conversions */
  static char spaces[] = "                                                  "
     "                                                                      ";
#define etSPACESIZE (sizeof(spaces)-1)
#ifndef etNOFLOATINGPOINT
  int  exp;                 /* exponent of real numbers */
  double rounder;           /* Used for rounding floating point values */

          length = precision;
        }else{
          length =1;
        }
        bufpt = buf;
        break;
      case etSTRING:
        zMem = bufpt = va_arg(ap,char*);
        if( bufpt==0 ) bufpt = "(null)";
        length = strlen(bufpt);
        if( precision>=0 && precision<length ) length = precision;
        break;
      case etSQLESCAPE:
      case etSQLESCAPE2:
        {

**    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.  Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.62 2002/08/14 03:03:57 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.

  WhereInfo *pWInfo;         /* Will become the return value of this function */
  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
  int brk, cont;             /* Addresses used during code generation */
  int *aOrder;         /* Order in which pTabList entries are searched */
  int nExpr;           /* Number of subexpressions in the WHERE clause */
  int loopMask;        /* One bit set for each outer loop */
  int haveKey;         /* True if KEY is on the stack */
  int aDirect[32];     /* If TRUE, then index this table using ROWID */
  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 expressions */

  /* pushKey is only allowed if there is a single table (as in an INSERT or
  ** UPDATE statement)

  ** doing a second read of the actual database table.
  **
  ** Actually, if there are more than 32 tables in the join, only the
  ** first 32 tables are candidates for indices.  This is (again) due
  ** to the limit of 32 bits in an integer bitmask.
  */
  loopMask = 0;
  for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(aDirect); i++){
    int j;
    int idx = aOrder[i];
    Table *pTab = pTabList->a[idx].pTab;
    Index *pIdx;
    Index *pBestIdx = 0;
    int bestScore = 0;