SQLite

**    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 1.328 2008/01/03 18:44:59 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

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

    }
  }
}


/*
** Generate code that will extract the iColumn-th column from
** table pTab and store the column value in register iMem, or on
** the stack if iMem==0.  There is an open cursor to pTab in 
** iTable.  If iColumn<0 then code is generated that extracts the rowid.
*/
void sqlite3ExprCodeGetColumn(
  Vdbe *v,         /* The VM being created */
  Table *pTab,     /* Description of the table we are reading from */
  int iColumn,     /* Index of the table column */
  int iTable,      /* The cursor pointing to the table */
  int iReg         /* Store results here */
){
  if( iColumn<0 ){
    int op = (pTab && IsVirtual(pTab)) ? OP_VRowid : OP_Rowid;
    sqlite3VdbeAddOp2(v, op, iTable, iReg);
  }else if( pTab==0 ){
    sqlite3VdbeAddOp3(v, OP_Column, iTable, iColumn, iReg);
  }else{
    int op = IsVirtual(pTab) ? OP_VColumn : OP_Column;
    sqlite3VdbeAddOp3(v, op, iTable, iColumn, iReg);
    sqlite3ColumnDefault(v, pTab, iColumn);
#ifndef SQLITE_OMIT_FLOATING_POINT
    if( pTab->aCol[iColumn].affinity==SQLITE_AFF_REAL ){
      sqlite3VdbeAddOp1(v, OP_RealAffinity, iReg);
    }
#endif
  }
}

/*
** Generate code into the current Vdbe to evaluate the given

    }
    case TK_COLUMN: {
      if( pExpr->iTable<0 ){
        /* This only happens when coding check constraints */
        assert( pParse->ckOffset>0 );
        sqlite3VdbeAddOp2(v, OP_Dup, pParse->ckOffset-pExpr->iColumn-1, 1);
      }else{
        sqlite3ExprCodeGetColumn(v, pExpr->pTab,
                                 pExpr->iColumn, pExpr->iTable, 0);
      }
      break;
    }
    case TK_INTEGER: {
      codeInteger(v, (char*)pExpr->token.z, pExpr->token.n, 0);
      break;
    }

** register number regardless.
**
** The current implementation is a rough prototype for experimental
** purposes.  There are many optimization opportunities here.
*/
int sqlite3ExprIntoReg(Parse *pParse, Expr *pExpr, int target){
  Vdbe *v = pParse->pVdbe;
  assert( v!=0 || pParse->db->mallocFailed );
  assert( pExpr!=0 || pParse->db->mallocFailed );
  if( v==0 || pExpr==0 ) return -1;

  if( target<=0 ){
    target = ++pParse->nMem;
  }
  if( pExpr->op==TK_COLUMN && pExpr->iTable>=0 ){
    sqlite3ExprCodeGetColumn(v, pExpr->pTab,
                             pExpr->iColumn, pExpr->iTable, target);
  }else{
    sqlite3ExprCode(pParse, pExpr);
    sqlite3VdbeAddOp2(v, OP_MemStore, target, 1);
  }
  return target;
}

/*
** Generate code that pushes the value of every element of the given
** expression list onto the stack.
**

**    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 1.382 2008/01/03 18:44:59 drh Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

        groupBySort = 1;
        sqlite3ExprCodeExprList(pParse, pGroupBy);
        sqlite3VdbeAddOp2(v, OP_Sequence, sAggInfo.sortingIdx, 0);
        j = pGroupBy->nExpr+1;
        for(i=0; i<sAggInfo.nColumn; i++){
          struct AggInfo_col *pCol = &sAggInfo.aCol[i];
          if( pCol->iSorterColumn<j ) continue;
          sqlite3ExprCodeGetColumn(v, pCol->pTab, pCol->iColumn,pCol->iTable,0);
          j++;
        }
        sqlite3VdbeAddOp2(v, OP_MakeRecord, j, 0);
        sqlite3VdbeAddOp2(v, OP_IdxInsert, sAggInfo.sortingIdx, 0);
        sqlite3WhereEnd(pWInfo);
        sqlite3VdbeAddOp2(v, OP_Sort, sAggInfo.sortingIdx, addrEnd);
        VdbeComment((v, "GROUP BY sort"));

/*
** 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 1.635 2008/01/03 18:44:59 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** The macro unlikely() is a hint that surrounds a boolean
** expression that is usually false.  Macro likely() surrounds

Table *sqlite3SrcListLookup(Parse*, SrcList*);
int sqlite3IsReadOnly(Parse*, Table*, int);
void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
void sqlite3DeleteFrom(Parse*, SrcList*, Expr*);
void sqlite3Update(Parse*, SrcList*, ExprList*, Expr*, int);
WhereInfo *sqlite3WhereBegin(Parse*, SrcList*, Expr*, ExprList**);
void sqlite3WhereEnd(WhereInfo*);
void sqlite3ExprCodeGetColumn(Vdbe*, Table*, int, int, int);
void sqlite3ExprCode(Parse*, Expr*);
void sqlite3ExprCodeAndCache(Parse*, Expr*);
int sqlite3ExprIntoReg(Parse*,Expr*,int);
int sqlite3ExprCodeExprList(Parse*, ExprList*);
void sqlite3ExprIfTrue(Parse*, Expr*, int, int);
void sqlite3ExprIfFalse(Parse*, Expr*, int, int);
Table *sqlite3FindTable(sqlite3*,const char*, const char*);

**
** 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 1.673 2008/01/03 18:44:59 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor

  }else{
    Release(pTos);
    pTos->flags = MEM_Int;
  }
  break;
}

/* Opcode: RealAffinity P1 * *
**
** If register P1 holds an integer convert it to a real value.
**
** This opcode is used when extracting information from a column that
** has REAL affinity.  Such column values may still be stored as
** integers, for space efficiency, but after extraction we want them
** to have only a real value.
*/
case OP_RealAffinity: {                  /* no-push */
  assert( pOp->p1>=0 && pOp->p1<=p->nMem );
  if( pOp->p1==0 ){
    if( pTos->flags & MEM_Int ){
      sqlite3VdbeMemRealify(pTos);
    }
  }else{
    Mem *pX = &p->aMem[pOp->p1];
    if( pX->flags & MEM_Int ){
      sqlite3VdbeMemRealify(pX);
    }
  }
  break;
}

#ifndef SQLITE_OMIT_CAST
/* Opcode: ToText * * *
**

  }else{
    pTos->flags = MEM_Null;
  }
  pTos->enc = SQLITE_UTF8;  /* In case the blob is ever cast to text */
  break;
}

/* Opcode: Rowid P1 P2 * * *
**
** Store in register P2 an integer which is the key of the table entry that
** P1 is currently point to.  If p2==0 then pust the integer.
*/
case OP_Rowid: {
  int i = pOp->p1;
  Cursor *pC;
  i64 v;
  Mem *pDest;

  assert( i>=0 && i<p->nCursor );
  pC = p->apCsr[i];
  assert( pC!=0 );
  rc = sqlite3VdbeCursorMoveto(pC);
  if( rc ) goto abort_due_to_error;
  if( pOp->p2>0 ){
    assert( pOp->p2<=p->nMem );
    pDest = &p->aMem[pOp->p2];
    sqlite3VdbeMemRelease(pDest);
  }else{
    pDest = ++pTos;
  }
  if( pC->rowidIsValid ){
    v = pC->lastRowid;
  }else if( pC->pseudoTable ){
    v = keyToInt(pC->iKey);
  }else if( pC->nullRow || pC->pCursor==0 ){
    pDest->flags = MEM_Null;
    break;
  }else{
    assert( pC->pCursor!=0 );
    sqlite3BtreeKeySize(pC->pCursor, &v);
    v = keyToInt(v);
  }
  pDest->u.i = v;
  pDest->flags = MEM_Int;
  break;
}

/* Opcode: NullRow P1 * *
**
** Move the cursor P1 to a null row.  Any OP_Column operations
** that occur while the cursor is on the null row will always push 

    pC->cacheStatus = CACHE_STALE;
  }
  Release(pTos);
  pTos--;
  break;
}

/* Opcode: IdxRowid P1 P2 * * *
**
** Write into register P2 an integer which is the last entry in the record at
** the end of the index key pointed to by cursor P1.  This integer should be
** the rowid of the table entry to which this index entry points.
**
** See also: Rowid, MakeIdxRec.
*/
case OP_IdxRowid: {
  int i = pOp->p1;
  BtCursor *pCrsr;
  Cursor *pC;
  Mem *pDest;

  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  if( pOp->p2>0 ){
    assert( pOp->p2<=p->nMem );
    pDest = &p->aMem[pOp->p2];
    sqlite3VdbeMemRelease(pDest);
  }else{
    pDest = ++pTos;
  }
  pDest->flags = MEM_Null;
  if( (pCrsr = (pC = p->apCsr[i])->pCursor)!=0 ){
    i64 rowid;

    assert( pC->deferredMoveto==0 );
    assert( pC->isTable==0 );
    if( pC->nullRow ){
      pDest->flags = MEM_Null;
    }else{
      rc = sqlite3VdbeIdxRowid(pCrsr, &rowid);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
      pDest->flags = MEM_Int;
      pDest->u.i = rowid;
    }
  }
  break;
}

/* Opcode: IdxGT P1 P2 *
**

  }

  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VRowid P1 P2 *
**
** Store into register P2  the rowid of
** the virtual-table that the P1 cursor is pointing to.
** If P2==0, push the value onto the stack.
*/
case OP_VRowid: {
  const sqlite3_module *pModule;

  Cursor *pCur = p->apCsr[pOp->p1];
  assert( pCur->pVtabCursor );
  pModule = pCur->pVtabCursor->pVtab->pModule;
  if( pModule->xRowid==0 ){
    sqlite3SetString(&p->zErrMsg, "Unsupported module operation: xRowid", 0);
    rc = SQLITE_ERROR;
  } else {
    sqlite_int64 iRow;
    Mem *pDest;

    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    rc = pModule->xRowid(pCur->pVtabCursor, &iRow);
    if( sqlite3SafetyOn(db) ) goto abort_due_to_misuse;

    if( pOp->p2>0 ){
      assert( pOp->p2<=p->nMem );
      pDest = &p->aMem[pOp->p2];
      sqlite3VdbeMemRelease(pDest);
    }else{
      pDest = ++pTos;
    }
    pDest->flags = MEM_Int;
    pDest->u.i = iRow;
  }

  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Opcode: VColumn P1 P2 P3
**
** Store the value of the P2-th column of
** the row of the virtual-table that the 
** P1 cursor is pointing to into register P3.
** Or if P3==0 push the value onto the stack.
*/
case OP_VColumn: {
  const sqlite3_module *pModule;

  Cursor *pCur = p->apCsr[pOp->p1];
  assert( pCur->pVtabCursor );
  pModule = pCur->pVtabCursor->pVtab->pModule;
  if( pModule->xColumn==0 ){
    sqlite3SetString(&p->zErrMsg, "Unsupported module operation: xColumn", 0);
    rc = SQLITE_ERROR;
  } else {
    Mem *pDest;
    sqlite3_context sContext;
    memset(&sContext, 0, sizeof(sContext));
    sContext.s.flags = MEM_Null;
    sContext.s.db = db;
    if( sqlite3SafetyOff(db) ) goto abort_due_to_misuse;
    rc = pModule->xColumn(pCur->pVtabCursor, &sContext, pOp->p2);

    /* Copy the result of the function to the top of the stack. We
    ** do this regardless of whether or not an error occured to ensure any
    ** dynamic allocation in sContext.s (a Mem struct) is  released.
    */
    sqlite3VdbeChangeEncoding(&sContext.s, encoding);
    if( pOp->p3>0 ){
      assert( pOp->p3<=p->nMem );
      pDest = &p->aMem[pOp->p3];
    }else{
      pDest = ++pTos;
      pDest->flags = 0;
    }
    sqlite3VdbeMemMove(pDest, &sContext.s);

    if( sqlite3SafetyOn(db) ){
      goto abort_due_to_misuse;
    }
    if( sqlite3VdbeMemTooBig(pDest) ){
      goto too_big;
    }
  }
  
  break;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */