SQLite

typedef struct ShellState ShellState;
struct ShellState {
  sqlite3 *db;           /* The database */
  int echoOn;            /* True to echo input commands */
  int autoExplain;       /* Automatically turn on .explain mode */
  int autoEQP;           /* Run EXPLAIN QUERY PLAN prior to seach SQL stmt */
  int statsOn;           /* True to display memory stats before each finalize */
  int vmstepsOn;         /* Display VM steps before each finalize */
  int scanstatsOn;       /* True to display scan stats before each finalize */
  int countChanges;      /* True to display change counts */
  int backslashOn;       /* Resolve C-style \x escapes in SQL input text */
  int outCount;          /* Revert to stdout when reaching zero */
  int cnt;               /* Number of records displayed so far */
  FILE *out;             /* Write results here */
  FILE *traceOut;        /* Output for sqlite3_trace() */

      exec_prepared_stmt(pArg, pStmt, xCallback);
      explain_data_delete(pArg);

      /* print usage stats if stats on */
      if( pArg && pArg->statsOn ){
        display_stats(db, pArg, 0);
      }

      if( pArg && pArg->vmstepsOn && pStmt ){
        int iCur = sqlite3_stmt_status(pStmt, SQLITE_STMTSTATUS_VM_STEP, 0);
        FILE *out = pArg->traceOut ? pArg->traceOut : pArg->out;
        raw_printf(out, "VM steps: %d\n", iCur);
      }

      /* print loop-counters if required */
      if( pArg && pArg->scanstatsOn ){
        display_scanstats(db, pArg);
      }

      /* Finalize the statement just executed. If this fails, save a

      sqlite3_file_control(p->db, zDbName, SQLITE_FCNTL_VFSNAME, &zVfsName);
      if( zVfsName ){
        utf8_printf(p->out, "%s\n", zVfsName);
        sqlite3_free(zVfsName);
      }
    }
  }else

  if( c=='v' && strncmp(azArg[0], "vmsteps", n)==0 ){
    if( nArg==2 ){
      p->vmstepsOn = booleanValue(azArg[1]);
    }else{
      raw_printf(stderr, "Usage: .vmsteps ?on|off?\n");
      rc = 1;
    }
  }else


#if defined(SQLITE_DEBUG) && defined(SQLITE_ENABLE_WHERETRACE)
  if( c=='w' && strncmp(azArg[0], "wheretrace", n)==0 ){
    sqlite3WhereTrace = nArg>=2 ? booleanValue(azArg[1]) : 0xff;
  }else
#endif

  if( pOp->p1==SQLITE_OK && p->pFrame ){
    /* Halt the sub-program. Return control to the parent frame. */
    pFrame = p->pFrame;
    p->pFrame = pFrame->pParent;
    p->nFrame--;
    sqlite3VdbeSetChanges(db, p->nChange);
    pcx = sqlite3VdbeFrameRestore(pFrame);
#ifdef SQLITE_TRACE_TRIGGER
    if( (db->mTrace & SQLITE_TRACE_STMT) && aOp[0].p4.z ){
      int nNest = 0;
      VdbeFrame *pF;
      int nTotal = nVmStep - pFrame->nVmStep;
      char *zTrace;
      assert( db->xTrace );
      for(pF=p->pFrame; pF; pF=pF->pParent) nNest++;
      zTrace = sqlite3_mprintf("%.*s%s completed (VM steps: total=%d self=%d)", 
          nNest, "                                                    :",
          aOp[0].p4.z, nTotal, nVmStep - pFrame->nVmStepAdj
      );
      if( zTrace ){
        (void)db->xTrace(SQLITE_TRACE_STMT, db->pTraceArg, 0, zTrace);
        sqlite3_free(zTrace);
      }
      if( p->pFrame ){
        p->pFrame->nVmStepAdj += nTotal;
      }
    }
#endif
    lastRowid = db->lastRowid;
    if( pOp->p2==OE_Ignore ){
      /* Instruction pcx is the OP_Program that invoked the sub-program 
      ** currently being halted. If the p2 instruction of this OP_Halt
      ** instruction is set to OE_Ignore, then the sub-program is throwing
      ** an IGNORE exception. In this case jump to the address specified
      ** as the p2 of the calling OP_Program.  */

    pFrame->nCursor = p->nCursor;
    pFrame->aOp = p->aOp;
    pFrame->nOp = p->nOp;
    pFrame->token = pProgram->token;
#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
    pFrame->anExec = p->anExec;
#endif
#ifdef SQLITE_TRACE_TRIGGER
    pFrame->nVmStep = nVmStep;
    pFrame->nVmStepAdj = nVmStep;
#endif

    pEnd = &VdbeFrameMem(pFrame)[pFrame->nChildMem];
    for(pMem=VdbeFrameMem(pFrame); pMem!=pEnd; pMem++){
      pMem->flags = MEM_Undefined;
      pMem->db = db;
    }
  }else{

#ifndef SQLITE_OMIT_DEPRECATED
    if( db->mTrace & SQLITE_TRACE_LEGACY ){
      void (*x)(void*,const char*) = (void(*)(void*,const char*))db->xTrace;
      char *z = sqlite3VdbeExpandSql(p, zTrace);
      x(db->pTraceArg, z);
      sqlite3_free(z);
    }else
#endif
#ifdef SQLITE_TRACE_TRIGGER
    if( p->pFrame ){
      int nNest = -1;
      VdbeFrame *pFrame;
      for(pFrame=p->pFrame; pFrame; pFrame=pFrame->pParent) nNest++;
      zTrace = sqlite3_mprintf("%.*s%s",
          nNest, "                                                    :", zTrace
      );
      if( zTrace ){
        (void)db->xTrace(SQLITE_TRACE_STMT, db->pTraceArg, p, zTrace);
        sqlite3_free(zTrace);
      }
    }else
#endif
    {
      (void)db->xTrace(SQLITE_TRACE_STMT, db->pTraceArg, p, zTrace);
    }
  }
#ifdef SQLITE_USE_FCNTL_TRACE
  zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql);

  int pc;                 /* Program Counter in parent (calling) frame */
  int nOp;                /* Size of aOp array */
  int nMem;               /* Number of entries in aMem */
  int nChildMem;          /* Number of memory cells for child frame */
  int nChildCsr;          /* Number of cursors for child frame */
  int nChange;            /* Statement changes (Vdbe.nChange)     */
  int nDbChange;          /* Value of db->nChange */
#ifdef SQLITE_TRACE_TRIGGER
  int nVmStep;            /* Value of nVmStep at start of program */
  int nVmStepAdj;         /* Adjusted for nested programs */
#endif
};

#define VdbeFrameMem(p) ((Mem *)&((u8 *)p)[ROUND8(sizeof(VdbeFrame))])

/*
** Internally, the vdbe manipulates nearly all SQL values as Mem
** structures. Each Mem struct may cache multiple representations (string,