**** This structure is defined inside of vdbeInt.h because it uses substructures** (Mem) which are only defined there.*/struct sqlite3_context {  FuncDef *pFunc;       /* Pointer to function information.  MUST BE FIRST */  VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */  Mem s;                /* The return value is stored here */  Mem *pMem;            /* Memory cell used to store aggregate context */  u8 isError;           /* Set to true for an error */  CollSeq *pColl;       /* Collating sequence */};/*** A Set structure is used for quick testing to see if a value** is part of a small set.  Sets are used to implement code like** this:**            x.y IN ('hi','hoo','hum')*/typedef struct Set Set;struct Set {  Hash hash;             /* A set is just a hash table */  HashElem *prev;        /* Previously accessed hash elemen */};/*** A FifoPage structure holds a single page of valves.  Pages are arranged** in a list.*/typedef struct FifoPage FifoPage;struct FifoPage {  int nSlot;         /* Number of entries aSlot[] */  int iWrite;        /* Push the next value into this entry in aSlot[] */  int iRead;         /* Read the next value from this entry in aSlot[] */  FifoPage *pNext;   /* Next page in the fifo */  i64 aSlot[1];      /* One or more slots for rowid values */};/*** The Fifo structure is typedef-ed in vdbeInt.h.  But the implementation** of that structure is private to this file.**** The Fifo structure describes the entire fifo.  */typedef struct Fifo Fifo;struct Fifo {  int nEntry;         /* Total number of entries */  FifoPage *pFirst;   /* First page on the list */  FifoPage *pLast;    /* Last page on the list */};/*** A Context stores the last insert rowid, the last statement change count,** and the current statement change count (i.e. changes since last statement).** The current keylist is also stored in the context.** Elements of Context structure type make up the ContextStack, which is** updated by the ContextPush and ContextPop opcodes (used by triggers).** The context is pushed before executing a trigger a popped when the** trigger finishes.*/typedef struct Context Context;struct Context {  i64 lastRowid;    /* Last insert rowid (sqlite3.lastRowid) */  int nChange;      /* Statement changes (Vdbe.nChanges)     */  Fifo sFifo;       /* Records that will participate in a DELETE or UPDATE */};/*** An instance of the virtual machine.  This structure contains the complete** state of the virtual machine.**** The "sqlite3_stmt" structure pointer that is returned by sqlite3_compile()** is really a pointer to an instance of this structure.*/struct Vdbe {  sqlite3 *db;        /* The whole database */  Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */  FILE *trace;        /* Write an execution trace here, if not NULL */  int nOp;            /* Number of instructions in the program */  int nOpAlloc;       /* Number of slots allocated for aOp[] */  Op *aOp;            /* Space to hold the virtual machine's program */  int nLabel;         /* Number of labels used */  int nLabelAlloc;    /* Number of slots allocated in aLabel[] */  int *aLabel;        /* Space to hold the labels */  Mem *aStack;        /* The operand stack, except string values */  Mem *pTos;          /* Top entry in the operand stack */  Mem **apArg;        /* Arguments to currently executing user function */  Mem *aColName;      /* Column names to return */  int nCursor;        /* Number of slots in apCsr[] */  Cursor **apCsr;     /* One element of this array for each open cursor */  int nVar;           /* Number of entries in aVar[] */  Mem *aVar;          /* Values for the OP_Variable opcode. */  char **azVar;       /* Name of variables */  int okVar;          /* True if azVar[] has been initialized */  int magic;              /* Magic number for sanity checking */  int nMem;               /* Number of memory locations currently allocated */  Mem *aMem;              /* The memory locations */  int nCallback;          /* Number of callbacks invoked so far */  int cacheCtr;           /* Cursor row cache generation counter */  Fifo sFifo;             /* A list of ROWIDs */  int contextStackTop;    /* Index of top element in the context stack */  int contextStackDepth;  /* The size of the "context" stack */  Context *contextStack;  /* Stack used by opcodes ContextPush & ContextPop*/  int pc;                 /* The program counter */  int rc;                 /* Value to return */  unsigned uniqueCnt;     /* Used by OP_MakeRecord when P2!=0 */  int errorAction;        /* Recovery action to do in case of an error */  int inTempTrans;        /* True if temp database is transactioned */  int returnStack[100];   /* Return address stack for OP_Gosub & OP_Return */  int returnDepth;        /* Next unused element in returnStack[] */  int nResColumn;         /* Number of columns in one row of the result set */  char **azResColumn;     /* Values for one row of result */   int popStack;           /* Pop the stack this much on entry to VdbeExec() */  char *zErrMsg;          /* Error message written here */  u8 resOnStack;          /* True if there are result values on the stack */  u8 explain;             /* True if EXPLAIN present on SQL command */  u8 changeCntOn;         /* True to update the change-counter */  u8 aborted;             /* True if ROLLBACK in another VM causes an abort */  u8 expired;             /* True if the VM needs to be recompiled */  u8 minWriteFileFormat;  /* Minimum file format for writable database files */  int nChange;            /* Number of db changes made since last reset */  i64 startTime;          /* Time when query started - used for profiling */#ifdef SQLITE_SSE  int fetchId;          /* Statement number used by sqlite3_fetch_statement */  int lru;              /* Counter used for LRU cache replacement */#endif};/*** The following are allowed values for Vdbe.magic*/#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */#define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated *//*** Function prototypes*/void sqlite3VdbeFreeCursor(Cursor*);void sqliteVdbePopStack(Vdbe*,int);int sqlite3VdbeCursorMoveto(Cursor*);#if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)void sqlite3VdbePrintOp(FILE*, int, Op*);#endif#ifdef SQLITE_DEBUGvoid sqlite3VdbePrintSql(Vdbe*);#endifint sqlite3VdbeSerialTypeLen(u32);u32 sqlite3VdbeSerialType(Mem*, int);int sqlite3VdbeSerialPut(unsigned char*, Mem*, int);int sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);void sqlite3VdbeDeleteAuxData(VdbeFunc*, int);int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);int sqlite3VdbeIdxRowid(BtCursor *, i64 *);int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);int sqlite3VdbeRecordCompare(void*,int,const void*,int, const void*);int sqlite3VdbeIdxRowidLen(const u8*);int sqlite3VdbeExec(Vdbe*);int sqlite3VdbeList(Vdbe*);int sqlite3VdbeHalt(Vdbe*);int sqlite3VdbeChangeEncoding(Mem *, int);int sqlite3VdbeMemCopy(Mem*, const Mem*);void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);int sqlite3VdbeMemMove(Mem*, Mem*);int sqlite3VdbeMemNulTerminate(Mem*);int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, void(*)(void*));void sqlite3VdbeMemSetInt64(Mem*, i64);void sqlite3VdbeMemSetDouble(Mem*, double);void sqlite3VdbeMemSetNull(Mem*);int sqlite3VdbeMemMakeWriteable(Mem*);int sqlite3VdbeMemDynamicify(Mem*);int sqlite3VdbeMemStringify(Mem*, int);i64 sqlite3VdbeIntValue(Mem*);int sqlite3VdbeMemIntegerify(Mem*);double sqlite3VdbeRealValue(Mem*);void sqlite3VdbeIntegerAffinity(Mem*);int sqlite3VdbeMemRealify(Mem*);int sqlite3VdbeMemNumerify(Mem*);int sqlite3VdbeMemFromBtree(BtCursor*,int,int,int,Mem*);void sqlite3VdbeMemRelease(Mem *p);int sqlite3VdbeMemFinalize(Mem*, FuncDef*);#ifndef NDEBUGvoid sqlite3VdbeMemSanity(Mem*);int sqlite3VdbeOpcodeNoPush(u8);#endifint sqlite3VdbeMemTranslate(Mem*, u8);void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);int sqlite3VdbeMemHandleBom(Mem *pMem);void sqlite3VdbeFifoInit(Fifo*);int sqlite3VdbeFifoPush(Fifo*, i64);int sqlite3VdbeFifoPop(Fifo*, i64*);void sqlite3VdbeFifoClear(Fifo*);