/*
** 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_FLOAT, SQLITE_TEXT or
** SQLITE_BLOB.
*/
struct Mem {
  i64 i;              /* Integer 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 MEM_Null, MEM_Str
												SQLITE_NULL, SQLITE_TEXT, etc. */
	u8  enc;            /* TEXT_Utf8, TEXT_Utf16le, or TEXT_Utf16be
												SQLITE_UTF8, SQLITE_UTF16BE or SQLITE_UTF16LE */
	double r;           /* Real value */
	char *z;            /* String or BLOB value */
	void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
	char zShort[NBFS];  /* Space for short strings */
};
typedef struct Mem Mem

/*
** Values are stored in the database in one of the following fundamental
** types.
*/
#define SQLITE_INTEGER  1
#define SQLITE_FLOAT    2
/* #define SQLITE_TEXT  3  // See below */
#define SQLITE_BLOB     4
#define SQLITE_NULL     5
/*
** SQLite version 2 defines SQLITE_TEXT differently.  To allow both
** version 2 and version 3 to be included, undefine them both if a
** conflict is seen.  Define SQLITE3_TEXT to be the version 3 value.
*/
#ifdef SQLITE_TEXT
# undef SQLITE_TEXT
#else
# define SQLITE_TEXT     3
#endif
#define SQLITE3_TEXT     3

/*
** 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 */