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vdbeInt.h
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00001 /*
00002 ** 2003 September 6
00003 **
00004 ** The author disclaims copyright to this source code.  In place of
00005 ** a legal notice, here is a blessing:
00006 **
00007 **    May you do good and not evil.
00008 **    May you find forgiveness for yourself and forgive others.
00009 **    May you share freely, never taking more than you give.
00010 **
00011 *************************************************************************
00012 ** This is the header file for information that is private to the
00013 ** VDBE.  This information used to all be at the top of the single
00014 ** source code file "vdbe.c".  When that file became too big (over
00015 ** 6000 lines long) it was split up into several smaller files and
00016 ** this header information was factored out.
00017 */
00018 
00019 /*
00020 ** intToKey() and keyToInt() used to transform the rowid.  But with
00021 ** the latest versions of the design they are no-ops.
00022 */
00023 #define keyToInt(X)   (X)
00024 #define intToKey(X)   (X)
00025 
00026 /*
00027 ** The makefile scans the vdbe.c source file and creates the following
00028 ** array of string constants which are the names of all VDBE opcodes.  This
00029 ** array is defined in a separate source code file named opcode.c which is
00030 ** automatically generated by the makefile.
00031 */
00032 extern char *sqlite3OpcodeNames[];
00033 
00034 /*
00035 ** SQL is translated into a sequence of instructions to be
00036 ** executed by a virtual machine.  Each instruction is an instance
00037 ** of the following structure.
00038 */
00039 typedef struct VdbeOp Op;
00040 
00041 /*
00042 ** Boolean values
00043 */
00044 typedef unsigned char Bool;
00045 
00046 /*
00047 ** A cursor is a pointer into a single BTree within a database file.
00048 ** The cursor can seek to a BTree entry with a particular key, or
00049 ** loop over all entries of the Btree.  You can also insert new BTree
00050 ** entries or retrieve the key or data from the entry that the cursor
00051 ** is currently pointing to.
00052 ** 
00053 ** Every cursor that the virtual machine has open is represented by an
00054 ** instance of the following structure.
00055 **
00056 ** If the Cursor.isTriggerRow flag is set it means that this cursor is
00057 ** really a single row that represents the NEW or OLD pseudo-table of
00058 ** a row trigger.  The data for the row is stored in Cursor.pData and
00059 ** the rowid is in Cursor.iKey.
00060 */
00061 struct Cursor {
00062   BtCursor *pCursor;    /* The cursor structure of the backend */
00063   int iDb;              /* Index of cursor database in db->aDb[] (or -1) */
00064   i64 lastRowid;        /* Last rowid from a Next or NextIdx operation */
00065   i64 nextRowid;        /* Next rowid returned by OP_NewRowid */
00066   Bool zeroed;          /* True if zeroed out and ready for reuse */
00067   Bool rowidIsValid;    /* True if lastRowid is valid */
00068   Bool atFirst;         /* True if pointing to first entry */
00069   Bool useRandomRowid;  /* Generate new record numbers semi-randomly */
00070   Bool nullRow;         /* True if pointing to a row with no data */
00071   Bool nextRowidValid;  /* True if the nextRowid field is valid */
00072   Bool pseudoTable;     /* This is a NEW or OLD pseudo-tables of a trigger */
00073   Bool deferredMoveto;  /* A call to sqlite3BtreeMoveto() is needed */
00074   Bool isTable;         /* True if a table requiring integer keys */
00075   Bool isIndex;         /* True if an index containing keys only - no data */
00076   u8 bogusIncrKey;      /* Something for pIncrKey to point to if pKeyInfo==0 */
00077   i64 movetoTarget;     /* Argument to the deferred sqlite3BtreeMoveto() */
00078   Btree *pBt;           /* Separate file holding temporary table */
00079   int nData;            /* Number of bytes in pData */
00080   char *pData;          /* Data for a NEW or OLD pseudo-table */
00081   i64 iKey;             /* Key for the NEW or OLD pseudo-table row */
00082   u8 *pIncrKey;         /* Pointer to pKeyInfo->incrKey */
00083   KeyInfo *pKeyInfo;    /* Info about index keys needed by index cursors */
00084   int nField;           /* Number of fields in the header */
00085   i64 seqCount;         /* Sequence counter */
00086 
00087   /* Cached information about the header for the data record that the
00088   ** cursor is currently pointing to.  Only valid if cacheValid is true.
00089   ** aRow might point to (ephemeral) data for the current row, or it might
00090   ** be NULL.
00091   */
00092   int cacheStatus;      /* Cache is valid if this matches Vdbe.cacheCtr */
00093   int payloadSize;      /* Total number of bytes in the record */
00094   u32 *aType;           /* Type values for all entries in the record */
00095   u32 *aOffset;         /* Cached offsets to the start of each columns data */
00096   u8 *aRow;             /* Data for the current row, if all on one page */
00097 };
00098 typedef struct Cursor Cursor;
00099 
00100 /*
00101 ** Number of bytes of string storage space available to each stack
00102 ** layer without having to malloc.  NBFS is short for Number of Bytes
00103 ** For Strings.
00104 */
00105 #define NBFS 32
00106 
00107 /*
00108 ** A value for Cursor.cacheValid that means the cache is always invalid.
00109 */
00110 #define CACHE_STALE 0
00111 
00112 /*
00113 ** Internally, the vdbe manipulates nearly all SQL values as Mem
00114 ** structures. Each Mem struct may cache multiple representations (string,
00115 ** integer etc.) of the same value.  A value (and therefore Mem structure)
00116 ** has the following properties:
00117 **
00118 ** Each value has a manifest type. The manifest type of the value stored
00119 ** in a Mem struct is returned by the MemType(Mem*) macro. The type is
00120 ** one of SQLITE_NULL, SQLITE_INTEGER, SQLITE_REAL, SQLITE_TEXT or
00121 ** SQLITE_BLOB.
00122 */
00123 struct Mem {
00124   i64 i;              /* Integer value. Or FuncDef* when flags==MEM_Agg */
00125   double r;           /* Real value */
00126   char *z;            /* String or BLOB value */
00127   int n;              /* Number of characters in string value, including '\0' */
00128   u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
00129   u8  type;           /* One of MEM_Null, MEM_Str, etc. */
00130   u8  enc;            /* TEXT_Utf8, TEXT_Utf16le, or TEXT_Utf16be */
00131   void (*xDel)(void *);  /* If not null, call this function to delete Mem.z */
00132   char zShort[NBFS];  /* Space for short strings */
00133 };
00134 typedef struct Mem Mem;
00135 
00136 /* One or more of the following flags are set to indicate the validOK
00137 ** representations of the value stored in the Mem struct.
00138 **
00139 ** If the MEM_Null flag is set, then the value is an SQL NULL value.
00140 ** No other flags may be set in this case.
00141 **
00142 ** If the MEM_Str flag is set then Mem.z points at a string representation.
00143 ** Usually this is encoded in the same unicode encoding as the main
00144 ** database (see below for exceptions). If the MEM_Term flag is also
00145 ** set, then the string is nul terminated. The MEM_Int and MEM_Real 
00146 ** flags may coexist with the MEM_Str flag.
00147 **
00148 ** Multiple of these values can appear in Mem.flags.  But only one
00149 ** at a time can appear in Mem.type.
00150 */
00151 #define MEM_Null      0x0001   /* Value is NULL */
00152 #define MEM_Str       0x0002   /* Value is a string */
00153 #define MEM_Int       0x0004   /* Value is an integer */
00154 #define MEM_Real      0x0008   /* Value is a real number */
00155 #define MEM_Blob      0x0010   /* Value is a BLOB */
00156 
00157 /* Whenever Mem contains a valid string or blob representation, one of
00158 ** the following flags must be set to determine the memory management
00159 ** policy for Mem.z.  The MEM_Term flag tells us whether or not the
00160 ** string is \000 or \u0000 terminated
00161 */
00162 #define MEM_Term      0x0020   /* String rep is nul terminated */
00163 #define MEM_Dyn       0x0040   /* Need to call sqliteFree() on Mem.z */
00164 #define MEM_Static    0x0080   /* Mem.z points to a static string */
00165 #define MEM_Ephem     0x0100   /* Mem.z points to an ephemeral string */
00166 #define MEM_Short     0x0200   /* Mem.z points to Mem.zShort */
00167 #define MEM_Agg       0x0400   /* Mem.z points to an agg function context */
00168 
00169 
00170 /* A VdbeFunc is just a FuncDef (defined in sqliteInt.h) that contains
00171 ** additional information about auxiliary information bound to arguments
00172 ** of the function.  This is used to implement the sqlite3_get_auxdata()
00173 ** and sqlite3_set_auxdata() APIs.  The "auxdata" is some auxiliary data
00174 ** that can be associated with a constant argument to a function.  This
00175 ** allows functions such as "regexp" to compile their constant regular
00176 ** expression argument once and reused the compiled code for multiple
00177 ** invocations.
00178 */
00179 struct VdbeFunc {
00180   FuncDef *pFunc;               /* The definition of the function */
00181   int nAux;                     /* Number of entries allocated for apAux[] */
00182   struct AuxData {
00183     void *pAux;                   /* Aux data for the i-th argument */
00184     void (*xDelete)(void *);      /* Destructor for the aux data */
00185   } apAux[1];                   /* One slot for each function argument */
00186 };
00187 typedef struct VdbeFunc VdbeFunc;
00188 
00189 /*
00190 ** The "context" argument for a installable function.  A pointer to an
00191 ** instance of this structure is the first argument to the routines used
00192 ** implement the SQL functions.
00193 **
00194 ** There is a typedef for this structure in sqlite.h.  So all routines,
00195 ** even the public interface to SQLite, can use a pointer to this structure.
00196 ** But this file is the only place where the internal details of this
00197 ** structure are known.
00198 **
00199 ** This structure is defined inside of vdbeInt.h because it uses substructures
00200 ** (Mem) which are only defined there.
00201 */
00202 struct sqlite3_context {
00203   FuncDef *pFunc;       /* Pointer to function information.  MUST BE FIRST */
00204   VdbeFunc *pVdbeFunc;  /* Auxilary data, if created. */
00205   Mem s;                /* The return value is stored here */
00206   Mem *pMem;            /* Memory cell used to store aggregate context */
00207   u8 isError;           /* Set to true for an error */
00208   CollSeq *pColl;       /* Collating sequence */
00209 };
00210 
00211 /*
00212 ** A Set structure is used for quick testing to see if a value
00213 ** is part of a small set.  Sets are used to implement code like
00214 ** this:
00215 **            x.y IN ('hi','hoo','hum')
00216 */
00217 typedef struct Set Set;
00218 struct Set {
00219   Hash hash;             /* A set is just a hash table */
00220   HashElem *prev;        /* Previously accessed hash elemen */
00221 };
00222 
00223 /*
00224 ** A FifoPage structure holds a single page of valves.  Pages are arranged
00225 ** in a list.
00226 */
00227 typedef struct FifoPage FifoPage;
00228 struct FifoPage {
00229   int nSlot;         /* Number of entries aSlot[] */
00230   int iWrite;        /* Push the next value into this entry in aSlot[] */
00231   int iRead;         /* Read the next value from this entry in aSlot[] */
00232   FifoPage *pNext;   /* Next page in the fifo */
00233   i64 aSlot[1];      /* One or more slots for rowid values */
00234 };
00235 
00236 /*
00237 ** The Fifo structure is typedef-ed in vdbeInt.h.  But the implementation
00238 ** of that structure is private to this file.
00239 **
00240 ** The Fifo structure describes the entire fifo.  
00241 */
00242 typedef struct Fifo Fifo;
00243 struct Fifo {
00244   int nEntry;         /* Total number of entries */
00245   FifoPage *pFirst;   /* First page on the list */
00246   FifoPage *pLast;    /* Last page on the list */
00247 };
00248 
00249 /*
00250 ** A Context stores the last insert rowid, the last statement change count,
00251 ** and the current statement change count (i.e. changes since last statement).
00252 ** The current keylist is also stored in the context.
00253 ** Elements of Context structure type make up the ContextStack, which is
00254 ** updated by the ContextPush and ContextPop opcodes (used by triggers).
00255 ** The context is pushed before executing a trigger a popped when the
00256 ** trigger finishes.
00257 */
00258 typedef struct Context Context;
00259 struct Context {
00260   i64 lastRowid;    /* Last insert rowid (sqlite3.lastRowid) */
00261   int nChange;      /* Statement changes (Vdbe.nChanges)     */
00262   Fifo sFifo;       /* Records that will participate in a DELETE or UPDATE */
00263 };
00264 
00265 /*
00266 ** An instance of the virtual machine.  This structure contains the complete
00267 ** state of the virtual machine.
00268 **
00269 ** The "sqlite3_stmt" structure pointer that is returned by sqlite3_compile()
00270 ** is really a pointer to an instance of this structure.
00271 */
00272 struct Vdbe {
00273   sqlite3 *db;        /* The whole database */
00274   Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */
00275   FILE *trace;        /* Write an execution trace here, if not NULL */
00276   int nOp;            /* Number of instructions in the program */
00277   int nOpAlloc;       /* Number of slots allocated for aOp[] */
00278   Op *aOp;            /* Space to hold the virtual machine's program */
00279   int nLabel;         /* Number of labels used */
00280   int nLabelAlloc;    /* Number of slots allocated in aLabel[] */
00281   int *aLabel;        /* Space to hold the labels */
00282   Mem *aStack;        /* The operand stack, except string values */
00283   Mem *pTos;          /* Top entry in the operand stack */
00284   Mem **apArg;        /* Arguments to currently executing user function */
00285   Mem *aColName;      /* Column names to return */
00286   int nCursor;        /* Number of slots in apCsr[] */
00287   Cursor **apCsr;     /* One element of this array for each open cursor */
00288   int nVar;           /* Number of entries in aVar[] */
00289   Mem *aVar;          /* Values for the OP_Variable opcode. */
00290   char **azVar;       /* Name of variables */
00291   int okVar;          /* True if azVar[] has been initialized */
00292   int magic;              /* Magic number for sanity checking */
00293   int nMem;               /* Number of memory locations currently allocated */
00294   Mem *aMem;              /* The memory locations */
00295   int nCallback;          /* Number of callbacks invoked so far */
00296   int cacheCtr;           /* Cursor row cache generation counter */
00297   Fifo sFifo;             /* A list of ROWIDs */
00298   int contextStackTop;    /* Index of top element in the context stack */
00299   int contextStackDepth;  /* The size of the "context" stack */
00300   Context *contextStack;  /* Stack used by opcodes ContextPush & ContextPop*/
00301   int pc;                 /* The program counter */
00302   int rc;                 /* Value to return */
00303   unsigned uniqueCnt;     /* Used by OP_MakeRecord when P2!=0 */
00304   int errorAction;        /* Recovery action to do in case of an error */
00305   int inTempTrans;        /* True if temp database is transactioned */
00306   int returnStack[100];   /* Return address stack for OP_Gosub & OP_Return */
00307   int returnDepth;        /* Next unused element in returnStack[] */
00308   int nResColumn;         /* Number of columns in one row of the result set */
00309   char **azResColumn;     /* Values for one row of result */ 
00310   int popStack;           /* Pop the stack this much on entry to VdbeExec() */
00311   char *zErrMsg;          /* Error message written here */
00312   u8 resOnStack;          /* True if there are result values on the stack */
00313   u8 explain;             /* True if EXPLAIN present on SQL command */
00314   u8 changeCntOn;         /* True to update the change-counter */
00315   u8 aborted;             /* True if ROLLBACK in another VM causes an abort */
00316   u8 expired;             /* True if the VM needs to be recompiled */
00317   u8 minWriteFileFormat;  /* Minimum file format for writable database files */
00318   int nChange;            /* Number of db changes made since last reset */
00319   i64 startTime;          /* Time when query started - used for profiling */
00320 #ifdef SQLITE_SSE
00321   int fetchId;          /* Statement number used by sqlite3_fetch_statement */
00322   int lru;              /* Counter used for LRU cache replacement */
00323 #endif
00324 };
00325 
00326 /*
00327 ** The following are allowed values for Vdbe.magic
00328 */
00329 #define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
00330 #define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
00331 #define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */
00332 #define VDBE_MAGIC_DEAD     0xb606c3c8    /* The VDBE has been deallocated */
00333 
00334 /*
00335 ** Function prototypes
00336 */
00337 void sqlite3VdbeFreeCursor(Cursor*);
00338 void sqliteVdbePopStack(Vdbe*,int);
00339 int sqlite3VdbeCursorMoveto(Cursor*);
00340 #if defined(SQLITE_DEBUG) || defined(VDBE_PROFILE)
00341 void sqlite3VdbePrintOp(FILE*, int, Op*);
00342 #endif
00343 #ifdef SQLITE_DEBUG
00344 void sqlite3VdbePrintSql(Vdbe*);
00345 #endif
00346 int sqlite3VdbeSerialTypeLen(u32);
00347 u32 sqlite3VdbeSerialType(Mem*, int);
00348 int sqlite3VdbeSerialPut(unsigned char*, Mem*, int);
00349 int sqlite3VdbeSerialGet(const unsigned char*, u32, Mem*);
00350 void sqlite3VdbeDeleteAuxData(VdbeFunc*, int);
00351 
00352 int sqlite2BtreeKeyCompare(BtCursor *, const void *, int, int, int *);
00353 int sqlite3VdbeIdxKeyCompare(Cursor*, int , const unsigned char*, int*);
00354 int sqlite3VdbeIdxRowid(BtCursor *, i64 *);
00355 int sqlite3MemCompare(const Mem*, const Mem*, const CollSeq*);
00356 int sqlite3VdbeRecordCompare(void*,int,const void*,int, const void*);
00357 int sqlite3VdbeIdxRowidLen(const u8*);
00358 int sqlite3VdbeExec(Vdbe*);
00359 int sqlite3VdbeList(Vdbe*);
00360 int sqlite3VdbeHalt(Vdbe*);
00361 int sqlite3VdbeChangeEncoding(Mem *, int);
00362 int sqlite3VdbeMemCopy(Mem*, const Mem*);
00363 void sqlite3VdbeMemShallowCopy(Mem*, const Mem*, int);
00364 int sqlite3VdbeMemMove(Mem*, Mem*);
00365 int sqlite3VdbeMemNulTerminate(Mem*);
00366 int sqlite3VdbeMemSetStr(Mem*, const char*, int, u8, void(*)(void*));
00367 void sqlite3VdbeMemSetInt64(Mem*, i64);
00368 void sqlite3VdbeMemSetDouble(Mem*, double);
00369 void sqlite3VdbeMemSetNull(Mem*);
00370 int sqlite3VdbeMemMakeWriteable(Mem*);
00371 int sqlite3VdbeMemDynamicify(Mem*);
00372 int sqlite3VdbeMemStringify(Mem*, int);
00373 i64 sqlite3VdbeIntValue(Mem*);
00374 int sqlite3VdbeMemIntegerify(Mem*);
00375 double sqlite3VdbeRealValue(Mem*);
00376 void sqlite3VdbeIntegerAffinity(Mem*);
00377 int sqlite3VdbeMemRealify(Mem*);
00378 int sqlite3VdbeMemNumerify(Mem*);
00379 int sqlite3VdbeMemFromBtree(BtCursor*,int,int,int,Mem*);
00380 void sqlite3VdbeMemRelease(Mem *p);
00381 int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
00382 #ifndef NDEBUG
00383 void sqlite3VdbeMemSanity(Mem*);
00384 int sqlite3VdbeOpcodeNoPush(u8);
00385 #endif
00386 int sqlite3VdbeMemTranslate(Mem*, u8);
00387 void sqlite3VdbeMemPrettyPrint(Mem *pMem, char *zBuf);
00388 int sqlite3VdbeMemHandleBom(Mem *pMem);
00389 void sqlite3VdbeFifoInit(Fifo*);
00390 int sqlite3VdbeFifoPush(Fifo*, i64);
00391 int sqlite3VdbeFifoPop(Fifo*, i64*);
00392 void sqlite3VdbeFifoClear(Fifo*);