SQLite

    pOut->u.i = ~sqlite3VdbeIntValue(pIn1);
  }
  break;
}

/* Opcode: Once P1 P2 * * *
**
** Fall through to the next instruction the first time this opcode is
** encountered on each invocation of the byte-code program.  Jump to P2
** on the second and all subsequent encounters during the same invocation.
**
** Top-level programs determine first invocation by comparing the P1
** operand against the P1 operand on the OP_Init opcode at the beginning
** of the program.  If the P1 values differ, then fall through and make
** the P1 of this opcode equal to the P1 of OP_Init.  If P1 values are
** the same then take the jump.
**
** For subprograms, there is a bitmask in the VdbeFrame that determines
** whether or not the jump should be taken.  The bitmask is necessary
** because the self-altering code trick does not work for recursive
** triggers.
*/
case OP_Once: {             /* jump */
  u32 iAddr;                /* Address of this instruction */
  assert( p->aOp[0].opcode==OP_Init );
  if( p->pFrame ){
    iAddr = (int)(pOp - p->aOp);
    if( (p->pFrame->aOnce[iAddr/8] & (1<<(iAddr & 7)))!=0 ){
      VdbeBranchTaken(1, 2);
      p->pFrame->aOnce[iAddr/8] |= 1<<(iAddr & 7);
      goto jump_to_p2;
    }
  }else{
    if( p->aOp[0].p1==pOp->p1 ){
      VdbeBranchTaken(1, 2);
      goto jump_to_p2;
    }
  }
  VdbeBranchTaken(0, 2);
  pOp->p1 = p->aOp[0].p1;
  break;
}

/* Opcode: If P1 P2 P3 * *
**
** Jump to P2 if the value in register P1 is true.  The value
** is considered true if it is numeric and non-zero.  If the value

    ** variable nMem (and later, VdbeFrame.nChildMem) to this value.
    */
    nMem = pProgram->nMem + pProgram->nCsr;
    assert( nMem>0 );
    if( pProgram->nCsr==0 ) nMem++;
    nByte = ROUND8(sizeof(VdbeFrame))
              + nMem * sizeof(Mem)
              + pProgram->nCsr * sizeof(VdbeCursor*)
              + (pProgram->nOp + 7)/8;
    pFrame = sqlite3DbMallocZero(db, nByte);
    if( !pFrame ){
      goto no_mem;
    }
    sqlite3VdbeMemRelease(pRt);
    pRt->flags = MEM_Frame;
    pRt->u.pFrame = pFrame;

  p->pAuxData = 0;
  p->nChange = 0;
  p->pFrame = pFrame;
  p->aMem = aMem = VdbeFrameMem(pFrame);
  p->nMem = pFrame->nChildMem;
  p->nCursor = (u16)pFrame->nChildCsr;
  p->apCsr = (VdbeCursor **)&aMem[p->nMem];
  pFrame->aOnce = (u8*)&p->apCsr[pProgram->nCsr];
  p->aOp = aOp = pProgram->aOp;
  p->nOp = pProgram->nOp;
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
  p->anExec = 0;
#endif
  pOp = &aOp[-1];

** A sub-routine used to implement a trigger program.
*/
struct SubProgram {
  VdbeOp *aOp;                  /* Array of opcodes for sub-program */
  int nOp;                      /* Elements in aOp[] */
  int nMem;                     /* Number of memory cells required */
  int nCsr;                     /* Number of cursors required */
  u8 *aOnce;                    /* Array of OP_Once flags */
  void *token;                  /* id that may be used to recursive triggers */
  SubProgram *pNext;            /* Next sub-program already visited */
};

/*
** A smaller version of VdbeOp used for the VdbeAddOpList() function because
** it takes up less space.

struct VdbeFrame {
  Vdbe *v;                /* VM this frame belongs to */
  VdbeFrame *pParent;     /* Parent of this frame, or NULL if parent is main */
  Op *aOp;                /* Program instructions for parent frame */
  i64 *anExec;            /* Event counters from parent frame */
  Mem *aMem;              /* Array of memory cells for parent frame */
  VdbeCursor **apCsr;     /* Array of Vdbe cursors for parent frame */
  u8 *aOnce;              /* Bitmask used by OP_Once */
  void *token;            /* Copy of SubProgram.token */
  i64 lastRowid;          /* Last insert rowid (sqlite3.lastRowid) */
  AuxData *pAuxData;      /* Linked list of auxdata allocations */
  int nCursor;            /* Number of entries in apCsr */
  int pc;                 /* Program Counter in parent (calling) frame */
  int nOp;                /* Size of aOp array */
  int nMem;               /* Number of entries in aMem */

# 2017-03-24
#
# 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.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix triggerG
ifcapable {!trigger} {
  finish_test
  return
}

# Test cases for ticket 
# https://www.sqlite.org/src/tktview/06796225f59c057cd120f
#
# The OP_Once opcode was not working correctly for recursive triggers.
#
do_execsql_test 100 {
  PRAGMA recursive_triggers = 1;
  
  CREATE TABLE t1(a);
  CREATE INDEX i1 ON t1(a);
  INSERT INTO t1(a) VALUES(0),(2),(3),(8),(9);
  CREATE TABLE t2(b);
  CREATE TABLE t3(c);
  
  CREATE TRIGGER tr AFTER INSERT ON t3 BEGIN
    INSERT INTO t3 SELECT new.c+1 WHERE new.c<5;
    INSERT INTO t2 SELECT new.c*100+a FROM t1 WHERE a IN (1, 2, 3, 4);
  END;
  
  INSERT INTO t3 VALUES(2);
  SELECT c FROM t3 ORDER BY c;;
} {2 3 4 5}
do_execsql_test 110 {
  SELECT b FROM t2 ORDER BY b;
} {202 203 302 303 402 403 502 503}

finish_test