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 1.333 2008/01/05 06:51:30 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

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

** Generate an instruction that will put the floating point
** value described by z[0..n-1] on the stack.
**
** The z[] string will probably not be zero-terminated.  But the 
** z[n] character is guaranteed to be something that does not look
** like the continuation of the number.
*/
static void codeReal(Vdbe *v, const char *z, int n, int negateFlag, int iMem){
  assert( z || v==0 || sqlite3VdbeDb(v)->mallocFailed );
  if( z ){
    double value;
    char *zV;
    assert( !isdigit(z[n]) );
    sqlite3AtoF(z, &value);
    if( negateFlag ) value = -value;
    zV = dup8bytes(v, (char*)&value);
    sqlite3VdbeAddOp4(v, OP_Real, 0, iMem, 0, zV, P4_REAL);
  }
}


/*
** Generate an instruction that will put the integer describe by
** text z[0..n-1] on the stack.
**
** The z[] string will probably not be zero-terminated.  But the 
** z[n] character is guaranteed to be something that does not look
** like the continuation of the number.
*/
static void codeInteger(Vdbe *v, const char *z, int n, int negFlag, int iMem){
  assert( z || v==0 || sqlite3VdbeDb(v)->mallocFailed );
  if( z ){
    int i;
    assert( !isdigit(z[n]) );
    if( sqlite3GetInt32(z, &i) ){
      if( negFlag ) i = -i;
      sqlite3VdbeAddOp2(v, OP_Integer, i, iMem);
    }else if( sqlite3FitsIn64Bits(z, negFlag) ){
      i64 value;
      char *zV;
      sqlite3Atoi64(z, &value);
      if( negFlag ) value = -value;
      zV = dup8bytes(v, (char*)&value);
      sqlite3VdbeAddOp4(v, OP_Int64, 0, iMem, 0, zV, P4_INT64);
    }else{
      codeReal(v, z, n, negFlag, iMem);
    }
  }
}


/*
** Generate code that will extract the iColumn-th column from

** below verify that the numbers are aligned correctly.
*/
int sqlite3ExprCode(Parse *pParse, Expr *pExpr, int target){
  Vdbe *v = pParse->pVdbe;
  int op;
  int inReg = 0;
  int stackChng = 0;
  int origTarget = target;

  assert( v!=0 || pParse->db->mallocFailed );
  if( v==0 ) return 0;
  if( target<0 ){
    target = ++pParse->nMem;
  }else if( target==0 ){
    stackChng = 1;

  }

  if( pExpr==0 ){
    op = TK_NULL;
  }else{
    op = pExpr->op;
  }
  switch( op ){
    case TK_AGG_COLUMN: {
      AggInfo *pAggInfo = pExpr->pAggInfo;
      struct AggInfo_col *pCol = &pAggInfo->aCol[pExpr->iAgg];
      if( !pAggInfo->directMode ){
        assert( pCol->iMem>0 );
        inReg = pCol->iMem;
        break;
      }else if( pAggInfo->useSortingIdx ){
        sqlite3VdbeAddOp3(v, OP_Column, pAggInfo->sortingIdx,
                              pCol->iSorterColumn, target);
        inReg = target;
        break;
      }
      /* Otherwise, fall thru into the TK_COLUMN case */
    }
    case TK_COLUMN: {
      if( pExpr->iTable<0 ){
        /* This only happens when coding check constraints */
        assert( pParse->ckOffset>0 );
        sqlite3VdbeAddOp1(v, OP_SCopy, -(pParse->ckOffset-pExpr->iColumn-1));
        /* inReg = -(pParse->ckOffset-pExpr->iColumn-1); */
      }else{
        sqlite3ExprCodeGetColumn(v, pExpr->pTab,
                                 pExpr->iColumn, pExpr->iTable, target);
        inReg = target;
      }
      break;
    }
    case TK_INTEGER: {
      codeInteger(v, (char*)pExpr->token.z, pExpr->token.n, 0, target);
      inReg = target;
      break;
    }
    case TK_FLOAT: {
      codeReal(v, (char*)pExpr->token.z, pExpr->token.n, 0, target);
      inReg = target;
      break;
    }
    case TK_STRING: {
      sqlite3DequoteExpr(pParse->db, pExpr);
      sqlite3VdbeAddOp4(v,OP_String8, 0, target, 0,
                        (char*)pExpr->token.z, pExpr->token.n);
      inReg = target;
      break;
    }
    case TK_NULL: {
      sqlite3VdbeAddOp2(v, OP_Null, 0, target);
      inReg = target;
      break;
    }
#ifndef SQLITE_OMIT_BLOB_LITERAL
    case TK_BLOB: {
      int n;
      const char *z;
      assert( TK_BLOB==OP_HexBlob );
      n = pExpr->token.n - 3;
      z = (char*)pExpr->token.z + 2;
      assert( n>=0 );
      if( n==0 ){
        z = "";
      }
      sqlite3VdbeAddOp4(v, op, 0, target, 0, z, n);
      inReg = target;
      break;
    }
#endif
    case TK_VARIABLE: {
      sqlite3VdbeAddOp2(v, OP_Variable, pExpr->iTable, target);
      if( pExpr->token.n>1 ){
        sqlite3VdbeChangeP4(v, -1, (char*)pExpr->token.z, pExpr->token.n);
      }
      inReg = target;
      break;
    }
    case TK_REGISTER: {
      inReg = pExpr->iTable;
      break;
    }
#ifndef SQLITE_OMIT_CAST
    case TK_CAST: {
      /* Expressions of the form:   CAST(pLeft AS token) */
      int aff, to_op;
      sqlite3ExprCode(pParse, pExpr->pLeft, target);
      aff = sqlite3AffinityType(&pExpr->token);
      to_op = aff - SQLITE_AFF_TEXT + OP_ToText;
      assert( to_op==OP_ToText    || aff!=SQLITE_AFF_TEXT    );
      assert( to_op==OP_ToBlob    || aff!=SQLITE_AFF_NONE    );
      assert( to_op==OP_ToNumeric || aff!=SQLITE_AFF_NUMERIC );
      assert( to_op==OP_ToInt     || aff!=SQLITE_AFF_INTEGER );
      assert( to_op==OP_ToReal    || aff!=SQLITE_AFF_REAL    );
      sqlite3VdbeAddOp1(v, to_op, target);
      stackChng = 0;
      inReg = target;
      break;
    }
#endif /* SQLITE_OMIT_CAST */
    case TK_LT:
    case TK_LE:
    case TK_GT:
    case TK_GE:

    }
    case TK_UMINUS: {
      Expr *pLeft = pExpr->pLeft;
      assert( pLeft );
      if( pLeft->op==TK_FLOAT || pLeft->op==TK_INTEGER ){
        Token *p = &pLeft->token;
        if( pLeft->op==TK_FLOAT ){
          codeReal(v, (char*)p->z, p->n, 1, target);
        }else{
          codeInteger(v, (char*)p->z, p->n, 1, target);
        }
        inReg = target;
        break;
      }
      /* Fall through into TK_NOT */
    }
    case TK_BITNOT:
    case TK_NOT: {
      assert( TK_BITNOT==OP_BitNot );
      assert( TK_NOT==OP_Not );
      sqlite3ExprCode(pParse, pExpr->pLeft, 0);
      sqlite3VdbeAddOp0(v, op);
      stackChng = 0;
      break;
    }
    case TK_ISNULL:
    case TK_NOTNULL: {
      int dest;
      assert( TK_ISNULL==OP_IsNull );
      assert( TK_NOTNULL==OP_NotNull );
      sqlite3VdbeAddOp2(v, OP_Integer, 1, target);
      sqlite3ExprCode(pParse, pExpr->pLeft, 0);
      dest = sqlite3VdbeCurrentAddr(v) + 2;
      sqlite3VdbeAddOp2(v, op, 1, dest);
      sqlite3VdbeAddOp2(v, OP_AddImm, target, -1);
      stackChng = 0;
      inReg = target;
      break;
    }
    case TK_AGG_FUNCTION: {
      AggInfo *pInfo = pExpr->pAggInfo;
      if( pInfo==0 ){
        sqlite3ErrorMsg(pParse, "misuse of aggregate: %T",
            &pExpr->span);
      }else{
        inReg = pInfo->aFunc[pExpr->iAgg].iMem;
      }
      break;
    }
    case TK_CONST_FUNC:
    case TK_FUNCTION: {
      ExprList *pList = pExpr->pList;
      int nExpr = pList ? pList->nExpr : 0;

    }
#ifndef SQLITE_OMIT_SUBQUERY
    case TK_EXISTS:
    case TK_SELECT: {
      if( pExpr->iColumn==0 ){
        sqlite3CodeSubselect(pParse, pExpr);
      }
      inReg = pExpr->iColumn;
      /* sqlite3VdbeAddOp1(v, OP_SCopy, pExpr->iColumn);
      VdbeComment((v, "load subquery result")); */
      break;
    }
    case TK_IN: {
      int addr;
      char affinity;
      int ckOffset = pParse->ckOffset;
      int eType;

      pRight = pLItem->pExpr;
      sqlite3ExprCode(pParse, pRight, 0);
      codeCompare(pParse, pLeft, pRight, OP_Le, 0, 0);
      sqlite3VdbeAddOp0(v, OP_And);
      break;
    }
    case TK_UPLUS: {
      inReg = sqlite3ExprCode(pParse, pExpr->pLeft, origTarget);
      stackChng = 0;
      break;
    }
    case TK_CASE: {
      int expr_end_label;
      int jumpInst;
      int nExpr;

          sqlite3VdbeAddOp1(v, OP_SCopy, -1);
          jumpInst = codeCompare(pParse, pExpr->pLeft, aListelem[i].pExpr,
                                 OP_Ne, 0, 1);
          sqlite3VdbeAddOp1(v, OP_Pop, 1);
        }else{
          jumpInst = sqlite3VdbeAddOp2(v, OP_IfNot, 1, 0);
        }
        sqlite3ExprCode(pParse, aListelem[i+1].pExpr, target);
        sqlite3VdbeAddOp2(v, OP_Goto, 0, expr_end_label);
        sqlite3VdbeJumpHere(v, jumpInst);
      }
      if( pExpr->pLeft ){
        sqlite3VdbeAddOp2(v, OP_Pop, 1, 0);
      }
      if( pExpr->pRight ){
        sqlite3ExprCode(pParse, pExpr->pRight, target);
      }else{
        sqlite3VdbeAddOp2(v, OP_Null, 0, target);
      }
      sqlite3VdbeResolveLabel(v, expr_end_label);
      inReg = target;
      break;
    }
#ifndef SQLITE_OMIT_TRIGGER
    case TK_RAISE: {
      if( !pParse->trigStack ){
        sqlite3ErrorMsg(pParse,
                       "RAISE() may only be used within a trigger-program");

         VdbeComment((v, "raise(IGNORE)"));
      }
      stackChng = 0;
      break;
    }
#endif
  }
  if( inReg!=target && origTarget!=-1 ){
    sqlite3VdbeAddOp2(v, (inReg>0 ? OP_SCopy : OP_Move), inReg, target);
    stackChng = 0;
  }
  if( pParse->ckOffset ){
    pParse->ckOffset += stackChng;
    assert( pParse->ckOffset );
  }
  return target;

**
** 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 1.683 2008/01/05 06:51:32 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

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

    pOp->p4type = P4_STATIC;
    pOp->p4.z = "";
  }

  /* Fall through to the next case, OP_Blob. */
}

/* Opcode: Blob P1 P2 * P4
**
** P4 points to a blob of data P1 bytes long.  Store this
** blob in register P2. This instruction is not coded directly
** by the compiler. Instead, the compiler layer specifies
** an OP_HexBlob opcode, with the hex string representation of
** the blob as P4. This opcode is transformed to an OP_Blob
** the first time it is executed.
*/
case OP_Blob: {                /* out2-prerelease */
  assert( pOp->p1 <= SQLITE_MAX_LENGTH );
  sqlite3VdbeMemSetStr(pOut, pOp->p4.z, pOp->p1, 0, 0);
  pOut->enc = encoding;
  break;
}
#endif /* SQLITE_OMIT_BLOB_LITERAL */

/* Opcode: Variable P1 * *
**
** The value of variable P1 is written into register P2 or pushed