SQLite

/*
** pExpr points to an expression which implements a function.  If
** it is appropriate to apply the LIKE optimization to that function
** then set aWc[0] through aWc[2] to the wildcard characters and
** return TRUE.  If the function is not a LIKE-style function then
** return FALSE.
**
** *pIsNocase is set to true if uppercase and lowercase are equivalent for
** the function (default for LIKE).  If the function makes the distinction
** between uppercase and lowercase (as does GLOB) then *pIsNocase is set to
** false.
*/
int sqlite3IsLikeFunction(sqlite3 *db, Expr *pExpr, int *pIsNocase, char *aWc){
  FuncDef *pDef;
  if( pExpr->op!=TK_FUNCTION 
   || !pExpr->x.pList 
   || pExpr->x.pList->nExpr!=2
  ){

  if( pSort->sortFlags & SORTFLAG_UseSorter ){
    op = OP_SorterInsert;
  }else{
    op = OP_IdxInsert;
  }
  sqlite3VdbeAddOp2(v, op, pSort->iECursor, regRecord);
  if( pSelect->iLimit ){
    int addr;
    int iLimit;
    if( pSelect->iOffset ){
      iLimit = pSelect->iOffset+1;
    }else{
      iLimit = pSelect->iLimit;
    }


    addr = sqlite3VdbeAddOp3(v, OP_IfNotZero, iLimit, 0, -1); VdbeCoverage(v);

    sqlite3VdbeAddOp1(v, OP_Last, pSort->iECursor);
    sqlite3VdbeAddOp1(v, OP_Delete, pSort->iECursor);
    sqlite3VdbeJumpHere(v, addr);
  }
}

/*
** Add code to implement the OFFSET
*/
static void codeOffset(

  }

  /* Jump to the end of the loop if the LIMIT is reached.  Except, if
  ** there is a sorter, in which case the sorter has already limited
  ** the output for us.
  */
  if( pSort==0 && p->iLimit ){
    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
  }
}

/*
** Allocate a KeyInfo object sufficient for an index of N key columns and
** X extra columns.
*/

      }else if( n>=0 && p->nSelectRow>(u64)n ){
        p->nSelectRow = n;
      }
    }else{
      sqlite3ExprCode(pParse, p->pLimit, iLimit);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit); VdbeCoverage(v);
      VdbeComment((v, "LIMIT counter"));
      sqlite3VdbeAddOp2(v, OP_IfNot, iLimit, iBreak); VdbeCoverage(v);
    }
    if( p->pOffset ){
      p->iOffset = iOffset = ++pParse->nMem;
      pParse->nMem++;   /* Allocate an extra register for limit+offset */
      sqlite3ExprCode(pParse, p->pOffset, iOffset);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset); VdbeCoverage(v);
      VdbeComment((v, "OFFSET counter"));

  /* Output the single row in Current */
  addrCont = sqlite3VdbeMakeLabel(v);
  codeOffset(v, regOffset, addrCont);
  selectInnerLoop(pParse, p, p->pEList, iCurrent,
      0, 0, pDest, addrCont, addrBreak);
  if( regLimit ){
    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, regLimit, addrBreak);
    VdbeCoverage(v);
  }
  sqlite3VdbeResolveLabel(v, addrCont);

  /* Execute the recursive SELECT taking the single row in Current as
  ** the value for the recursive-table. Store the results in the Queue.
  */

      if( rc ){
        goto multi_select_end;
      }
      p->pPrior = 0;
      p->iLimit = pPrior->iLimit;
      p->iOffset = pPrior->iOffset;
      if( p->iLimit ){
        addr = sqlite3VdbeAddOp1(v, OP_IfNot, p->iLimit); VdbeCoverage(v);
        VdbeComment((v, "Jump ahead if LIMIT reached"));
      }
      explainSetInteger(iSub2, pParse->iNextSelectId);
      rc = sqlite3Select(pParse, p, &dest);
      testcase( rc!=SQLITE_OK );
      pDelete = p->pPrior;
      p->pPrior = pPrior;

      break;
    }
  }

  /* Jump to the end of the loop if the LIMIT is reached.
  */
  if( p->iLimit ){
    sqlite3VdbeAddOp2(v, OP_DecrJumpZero, p->iLimit, iBreak); VdbeCoverage(v);
  }

  /* Generate the subroutine return
  */
  sqlite3VdbeResolveLabel(v, iContinue);
  sqlite3VdbeAddOp1(v, OP_Return, regReturn);

  break;
}
#endif /* SQLITE_OMIT_AUTOINCREMENT */

/* Opcode: IfPos P1 P2 * * *
** Synopsis: if r[P1]>0 goto P2
**
** Register P1 must contain an integer.
** If the value of register P1 is 1 or greater, jump to P2 and
** add the literal value P3 to register P1.
**
** If the initial value of register P1 is less than 1, then the

** value is unchanged and control passes through to the next instruction.
*/
case OP_IfPos: {        /* jump, in1 */
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags&MEM_Int );
  VdbeBranchTaken( pIn1->u.i>0, 2);
  if( pIn1->u.i>0 ){
     pc = pOp->p2 - 1;

  VdbeBranchTaken(pIn1->u.i<0, 2);
  if( pIn1->u.i<0 ){
     pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: IfNotZero P1 P2 P3 * *
** Synopsis: if r[P1]!=0 then r[P1]+=P3, goto P2
**
** Register P1 must contain an integer.  If the content of register P1 is
** initially nonzero, then add P3 to P1 and jump to P2.  If register P1 is
** initially zero, leave it unchanged and fall through.
*/
case OP_IfNotZero: {        /* jump, in1 */
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags&MEM_Int );
  VdbeBranchTaken(pIn1->u.i<0, 2);
  if( pIn1->u.i ){
     pIn1->u.i += pOp->p3;
     pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: DecrJumpZero P1 P2 * * *
** Synopsis: if (--r[P1])==0 goto P2
**
** Register P1 must hold an integer.  Decrement the value in register P1
** then jump to P2 if the new value is exactly zero.
*/
case OP_DecrJumpZero: {      /* jump, in1 */
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags&MEM_Int );
  pIn1->u.i--;
  VdbeBranchTaken(pIn1->u.i==0, 2);
  if( pIn1->u.i==0 ){
     pc = pOp->p2 - 1;
  }
  break;
}


/* Opcode: JumpZeroIncr P1 P2 * * *
** Synopsis: if (r[P1]++)==0 ) goto P2
**
** The register P1 must contain an integer.  If register P1 is initially
** zero, then jump to P2.  Increment register P1 regardless of whether or
** not the jump is taken.
*/
case OP_JumpZeroIncr: {        /* jump, in1 */
  pIn1 = &aMem[pOp->p1];
  assert( pIn1->flags&MEM_Int );
  VdbeBranchTaken(pIn1->u.i==0, 2);
  if( (pIn1->u.i++)==0 ){
     pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: AggStep * P2 P3 P4 P5
** Synopsis: accum=r[P3] step(r[P2@P5])
**
** Execute the step function for an aggregate.  The
** function has P5 arguments.   P4 is a pointer to the FuncDef
** structure that specifies the function.  Use register
** P3 as the accumulator.

#endif

/*
** Look at the last instruction coded.  If that instruction is OP_String8
** and if pLoop->iLikeRepCntr is non-zero, then change the P3 to be
** pLoop->iLikeRepCntr and set P5.
**
** The LIKE optimization trys to evaluate "x LIKE 'abc%'" as a range
** expression: "x>='ABC' AND x<'abd'".  But this requires that the range
** scan loop run twice, once for strings and a second time for BLOBs.
** The OP_String opcodes on the second pass convert the upper and lower
** bound string contants to blobs.  This routine makes the necessary changes
** to the OP_String opcodes for that to happen.
*/
static void whereLikeOptimizationStringFixup(Vdbe *v, WhereLevel *pLevel){
  VdbeOp *pOp;
  pOp = sqlite3VdbeGetOp(v, -1);
  if( pLevel->iLikeRepCntr && pOp->opcode==OP_String8 ){
    pOp->p3 = pLevel->iLikeRepCntr;
    pOp->p5 = 1;
  }
}

/*
** Generate code for the start of the iLevel-th loop in the WHERE clause

      nExtraReg = 1;
      if( pRangeStart
       && (pRangeStart->wtFlags & TERM_LIKEOPT)!=0
       && (pRangeEnd->wtFlags & TERM_LIKEOPT)!=0
      ){
        pLevel->iLikeRepCntr = ++pParse->nMem;
        sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLikeRepCntr);
        VdbeComment((v, "LIKE loop counter"));
        pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
      }
      if( pRangeStart==0
       && (j = pIdx->aiColumn[nEq])>=0 
       && pIdx->pTable->aCol[j].notNull==0
      ){
        bSeekPastNull = 1;

    ** start and end terms (pRangeStart and pRangeEnd).
    */
    if( (nEq<pIdx->nKeyCol && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC))
     || (bRev && pIdx->nKeyCol==nEq)
    ){
      SWAP(WhereTerm *, pRangeEnd, pRangeStart);
      SWAP(u8, bSeekPastNull, bStopAtNull);
      if( pLevel->addrLikeRep ){
        sqlite3VdbeChangeP1(v, pLevel->addrLikeRep-1, 1);
      }
    }

    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );
    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 );
    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 );
    startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);

    pE = pTerm->pExpr;
    assert( pE!=0 );
    if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
      continue;
    }
    if( pTerm->wtFlags & TERM_LIKECOND ){
      assert( pLevel->iLikeRepCntr>0 );
      skipLikeAddr = sqlite3VdbeAddOp1(v, OP_IfNot, pLevel->iLikeRepCntr);
      VdbeCoverage(v);
    }
    sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
    if( skipLikeAddr ) sqlite3VdbeJumpHere(v, skipLikeAddr);
    pTerm->wtFlags |= TERM_CODED;
  }

    if( pLevel->addrSkip ){
      sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrSkip);
      VdbeComment((v, "next skip-scan on %s", pLoop->u.btree.pIndex->zName));
      sqlite3VdbeJumpHere(v, pLevel->addrSkip);
      sqlite3VdbeJumpHere(v, pLevel->addrSkip-2);
    }
    if( pLevel->addrLikeRep ){


      sqlite3VdbeAddOp2(v,
           pLevel->op==OP_Prev ? OP_DecrJumpZero : OP_JumpZeroIncr,
           pLevel->iLikeRepCntr, pLevel->addrLikeRep);
      VdbeCoverage(v);
    }
    if( pLevel->iLeftJoin ){
      addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin); VdbeCoverage(v);
      assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
           || (pLoop->wsFlags & WHERE_INDEXED)!=0 );
      if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 ){
        sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor);

  INSERT INTO t2 SELECT a, b FROM t1;
  CREATE INDEX t2ba ON t2(b,a);
  SELECT a, b FROM t2 WHERE b GLOB 'ab*' ORDER BY +a;
} {1 abc 4 abc}
do_execsql_test like3-1.4 {
  SELECT a, b FROM t2 WHERE +b GLOB 'ab*' ORDER BY +a;
} {1 abc 4 abc}

do_execsql_test like3-3.0 {
  CREATE TABLE t3(x TEXT PRIMARY KEY COLLATE nocase);
  INSERT INTO t3(x) VALUES('aaa'),('abc'),('abd'),('abe'),('acz');
  INSERT INTO t3(x) SELECT CAST(x AS blob) FROM t3;
  SELECT quote(x) FROM t3 WHERE x LIKE 'ab%' ORDER BY x;
} {'abc' 'abd' 'abe' X'616263' X'616264' X'616265'}
do_execsql_test like3-3.1 {
  SELECT quote(x) FROM t3 WHERE x LIKE 'ab%' ORDER BY x DESC;
} {X'616265' X'616264' X'616263' 'abe' 'abd' 'abc'}
do_execsql_test like3-3.1ck {
  SELECT quote(x) FROM t3 WHERE x LIKE 'ab%' ORDER BY +x DESC;
} {X'616265' X'616264' X'616263' 'abe' 'abd' 'abc'}


finish_test