text: /*
  ** 2003 September 6
  **
  ** 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.
  **
  *************************************************************************
  ** This is the header file for information that is private to the
  ** VDBE.  This information used to all be at the top of the single
  ** source code file "vdbe.c".  When that file became too big (over
  ** 6000 lines long) it was split up into several smaller files and
  ** this header information was factored out.
  */
  #ifndef _VDBEINT_H_
  #define _VDBEINT_H_
  
  /*
  ** intToKey() and keyToInt() used to transform the rowid.  But with
  ** the latest versions of the design they are no-ops.
  */
  #define keyToInt(X)   (X)
  #define intToKey(X)   (X)
  
  
  /*
  ** SQL is translated into a sequence of instructions to be
  ** executed by a virtual machine.  Each instruction is an instance
  ** of the following structure.
  */
  typedef struct VdbeOp Op;
  
  /*
  ** Boolean values
  */
  typedef unsigned char Bool;
  
  /*
  ** A cursor is a pointer into a single BTree within a database file.
  ** The cursor can seek to a BTree entry with a particular key, or
  ** loop over all entries of the Btree.  You can also insert new BTree
  ** entries or retrieve the key or data from the entry that the cursor
  ** is currently pointing to.
  ** 
  ** Every cursor that the virtual machine has open is represented by an
  ** instance of the following structure.
  **
  ** If the Cursor.isTriggerRow flag is set it means that this cursor is
  ** really a single row that represents the NEW or OLD pseudo-table of
  ** a row trigger.  The data for the row is stored in Cursor.pData and
  ** the rowid is in Cursor.iKey.
  */
  struct Cursor {
    BtCursor *pCursor;    /* The cursor structure of the backend */
    int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
    i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */
    i64 nextRowid;        /* Next rowid returned by OP_NewRowid */
    Bool zeroed;          /* True if zeroed out and ready for reuse */
    Bool rowidIsValid;    /* True if lastRowid is valid */
    Bool atFirst;         /* True if pointing to first entry */
    Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
    Bool nullRow;         /* True if pointing to a row with no data */
    Bool nextRowidValid;  /* True if the nextRowid field is valid */
    Bool pseudoTable;     /* This is a NEW or OLD pseudo-tables of a trigger */
    Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
    Bool isTable;         /* True if a table requiring integer keys */
    Bool isIndex;         /* True if an index containing keys only - no data */
    u8 bogusIncrKey;      /* Something for pIncrKey to point to if pKeyInfo==0 */
    i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
    Btree *pBt;           /* Separate file holding temporary table */
    int nData;            /* Number of bytes in pData */
    char *pData;          /* Data for a NEW or OLD pseudo-table */
    i64 iKey;             /* Key for the NEW or OLD pseudo-table row */
    u8 *pIncrKey;         /* Pointer to pKeyInfo->incrKey */
    KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
    int nField;           /* Number of fields in the header */
    i64 seqCount;         /* Sequence counter */
    sqlite3_vtab_cursor *pVtabCursor;  /* The cursor for a virtual table */
    const sqlite3_module *pModule;     /* Module for cursor pVtabCursor */
  
    /* Cached information about the header for the data record that the
    ** cursor is currently pointing to.  Only valid if cacheValid is true.
    ** aRow might point to (ephemeral) data for the current row, or it might
    ** be NULL.
    */
    int cacheStatus;      /* Cache is valid if this matches Vdbe.cacheCtr */
    int payloadSize;      /* Total number of bytes in the record */
    u32 *aType;           /* Type values for all entries in the record */
    u32 *aOffset;         /* Cached offsets to the start of each columns data */
    u8 *aRow;             /* Data for the current row, if all on one page */
  };
  typedef struct Cursor Cursor;
  
  /*
  ** Number of bytes of string storage space available to each stack
  ** layer without having to malloc.  NBFS is short for Number of Bytes
  ** For Strings.
  */
  #define NBFS 32
  
  /*
  ** A value for Cursor.cacheValid that means the cache is always invalid.
  */
  #define CACHE_STALE 0
  
  /*
  ** Internally, the vdbe manipulates nearly all SQL values as Mem
  ** structures. Each Mem struct may cache multiple representations (string,
  ** integer etc.) of the same value.  A value (and therefore Mem structure)
  ** has the following properties:
  **
  ** Each value has a manifest type. The manifest type of the value stored
  ** in a Mem struct is returned by the MemType(Mem*) macro. The type is
  ** one of SQLITE_NULL, SQLITE_INTEGER, SQLITE_REAL, SQLITE_TEXT or
  ** SQLITE_BLOB.
  */
  struct Mem {
    union {
      i64 i;              /* Integer value. Or FuncDef* when flags==MEM_Agg */
      FuncDef *pDef;      /* Used only when flags==MEM_Agg */
    } u;
    double r;           /* Real value */
    sqlite3 *db;        /* The associated database connection */
    char *z;            /* String or BLOB value */
    int n;              /* Number of characters in string value, including '\0' */
    u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
    u8  type;           /* One of SQLITE_NULL, SQLITE_TEXT, SQLITE_INTEGER, etc */
    u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
    void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
    char zShort[NBFS];  /* Space for short strings */
  };
  typedef struct Mem Mem;
  
  /* One or more of the following flags are set to indicate the validOK
  ** representations of the value stored in the Mem struct.
  **
  ** If the MEM_Null flag is set, then the value is an SQL NULL value.
  ** No other flags may be set in this case.
  **
  ** If the MEM_Str flag is set then Mem.z points at a string representation.
  ** Usually this is encoded in the same unicode encoding as the main
  ** database (see below for exceptions). If the MEM_Term flag is also
  ** set, then the string is nul terminated. The MEM_Int and MEM_Real 
  ** flags may coexist with the MEM_Str flag.
  **
  ** Multiple of these values can appear in Mem.flags.  But only one
  ** at a time can appear in Mem.type.
  */
  #define MEM_Null      0x0001   /* Value is NULL */
  #define MEM_Str       0x0002   /* Value is a string */
  #define MEM_Int       0x0004   /* Value is an integer */
  #define MEM_Real      0x0008   /* Value is a real number */
  #define MEM_Blob      0x0010   /* Value is a BLOB */
  
  /* Whenever Mem contains a valid string or blob representation, one of
  ** the following flags must be set to determine the memory management
  ** policy for Mem.z.  The MEM_Term flag tells us whether or not the
  ** string is \000 or \u0000 terminated
  */
  #define MEM_Term      0x0020   /* String rep is nul terminated */
  #define MEM_Dyn       0x0040   /* Need to call sqliteFree() on Mem.z */
  #define MEM_Static    0x0080   /* Mem.z points to a static string */
  #define MEM_Ephem     0x0100   /* Mem.z points to an ephemeral string */
  #define MEM_Short     0x0200   /* Mem.z points to Mem.zShort */
  #define MEM_Agg       0x0400   /* Mem.z points to an agg function context */
  #define MEM_Zero      0x0800   /* Mem.i contains count of 0s appended to blob */
  
  #ifdef SQLITE_OMIT_INCRBLOB
    #undef MEM_Zero
    #define MEM_Zero 0x0000
  #endif
  
  
  /* A VdbeFunc is just a FuncDef (defined in sqliteInt.h) that contains
  ** additional information about auxiliary information bound to arguments
  ** of the function.  This is used to implement the sqlite3_get_auxdata()
  ** and sqlite3_set_auxdata() APIs.  The "auxdata" is some auxiliary data
  ** that can be associated with a constant argument to a function.  This
  ** allows functions such as "regexp" to compile their constant regular
  ** expression argument once and reused the compiled code for multiple
  ** invocations.
  */
  struct VdbeFunc {
    FuncDef *pFunc;               /* The definition of the function */
    int nAux;                     /* Number of entries allocated for apAux[] */
    struct AuxData {
      void *pAux;                   /* Aux data for the i-th argument */
      void (*xDelete)(void *);      /* Destructor for the aux data */
    } apAux[1];                   /* One slot for each function argument */
  };
  typedef struct VdbeFunc VdbeFunc;
  
  /*
  ** The "context" argument for a installable function.  A pointer to an
  ** instance of this structure is the first argument to the routines used
  ** implement the SQL functions.
  **
  ** There is a typedef for this structure in sqlite.h.  So all routines,
  ** even the public interface to SQLite, can use a pointer to this structure.
  ** But this file is the only place where the internal details of this
  ** structure are known.
  **
  ** 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.
  **
  ** The Vdbe.inVtabMethod variable is set to non-zero for the duration of
  ** any virtual table method invocations made by the vdbe program. It is
  ** set to 2 for xDestroy method calls and 1 for all other methods. This
  ** variable is used for two purposes: to allow xDestroy methods to execute
  ** "DROP TABLE" statements and to prevent some nasty side effects of
  ** malloc failure when SQLite is invoked recursively by a virtual table 
  ** method function.
  */
  struct Vdbe {
    sqlite3 *db;        /* The whole database */
    Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */
    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[25];    /* 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 */
    u8 inVtabMethod;        /* See comments above */
    int nChange;            /* Number of db changes made since last reset */
    i64 startTime;          /* Time when query started - used for profiling */
    int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
    BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
    int nSql;             /* Number of bytes in zSql */
    char *zSql;           /* Text of the SQL statement that generated this */
  #ifdef SQLITE_DEBUG
    FILE *trace;        /* Write an execution trace here, if not NULL */
  #endif
    int openedStatement;  /* True if this VM has opened a statement journal */
  #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(Vdbe *, Cursor*);
  void sqliteVdbePopStack(Vdbe*,int);
  int sqlite3VdbeCursorMoveto(Cursor*);
  #if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
  void sqlite3VdbePrintOp(FILE*, int, Op*);
  #endif
  int sqlite3VdbeSerialTypeLen(u32);
  u32 sqlite3VdbeSerialType(Mem*, int);
  int sqlite3VdbeSerialPut(unsigned char*, int, 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 sqlite3VdbeMemTooBig(Mem*);
  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*);
  void sqlite3VdbeMemSetZeroBlob(Mem*,int);
  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*);
  const char *sqlite3OpcodeName(int);
  
  #ifndef NDEBUG
    void sqlite3VdbeMemSanity(Mem*);
    int sqlite3VdbeOpcodeNoPush(u8);
  #endif
  int sqlite3VdbeMemTranslate(Mem*, u8);
  #ifdef SQLITE_DEBUG
    void sqlite3VdbePrintSql(Vdbe*);
    void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
  #endif
  int sqlite3VdbeMemHandleBom(Mem *pMem);
  void sqlite3VdbeFifoInit(Fifo*);
  int sqlite3VdbeFifoPush(Fifo*, i64);
  int sqlite3VdbeFifoPop(Fifo*, i64*);
  void sqlite3VdbeFifoClear(Fifo*);
  
  #ifndef SQLITE_OMIT_INCRBLOB
    int sqlite3VdbeMemExpandBlob(Mem *);
  #else
    #define sqlite3VdbeMemExpandBlob(x) SQLITE_OK
  #endif
  
  #endif /* !defined(_VDBEINT_H_) */
  