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304 lines
13 KiB
304 lines
13 KiB
/*
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** 2003 September 6
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This is the header file for information that is private to the
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** VDBE. This information used to all be at the top of the single
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** source code file "vdbe.c". When that file became too big (over
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** 6000 lines long) it was split up into several smaller files and
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** this header information was factored out.
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*/
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/*
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** When converting from the native format to the key format and back
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** again, in addition to changing the byte order we invert the high-order
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** bit of the most significant byte. This causes negative numbers to
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** sort before positive numbers in the memcmp() function.
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*/
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#define keyToInt(X) (sqliteVdbeByteSwap(X) ^ 0x80000000)
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#define intToKey(X) (sqliteVdbeByteSwap((X) ^ 0x80000000))
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/*
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** The makefile scans this source file and creates the following
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** array of string constants which are the names of all VDBE opcodes.
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** This array is defined in a separate source code file named opcode.c
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** which is automatically generated by the makefile.
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*/
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extern char *sqliteOpcodeNames[];
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/*
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** SQL is translated into a sequence of instructions to be
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** executed by a virtual machine. Each instruction is an instance
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** of the following structure.
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*/
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typedef struct VdbeOp Op;
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/*
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** Boolean values
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*/
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typedef unsigned char Bool;
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/*
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** A cursor is a pointer into a single BTree within a database file.
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** The cursor can seek to a BTree entry with a particular key, or
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** loop over all entries of the Btree. You can also insert new BTree
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** entries or retrieve the key or data from the entry that the cursor
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** is currently pointing to.
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**
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** Every cursor that the virtual machine has open is represented by an
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** instance of the following structure.
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**
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** If the Cursor.isTriggerRow flag is set it means that this cursor is
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** really a single row that represents the NEW or OLD pseudo-table of
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** a row trigger. The data for the row is stored in Cursor.pData and
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** the rowid is in Cursor.iKey.
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*/
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struct Cursor {
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BtCursor *pCursor; /* The cursor structure of the backend */
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int lastRecno; /* Last recno from a Next or NextIdx operation */
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int nextRowid; /* Next rowid returned by OP_NewRowid */
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Bool recnoIsValid; /* True if lastRecno is valid */
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Bool keyAsData; /* The OP_Column command works on key instead of data */
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Bool atFirst; /* True if pointing to first entry */
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Bool useRandomRowid; /* Generate new record numbers semi-randomly */
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Bool nullRow; /* True if pointing to a row with no data */
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Bool nextRowidValid; /* True if the nextRowid field is valid */
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Bool pseudoTable; /* This is a NEW or OLD pseudo-tables of a trigger */
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Bool deferredMoveto; /* A call to sqliteBtreeMoveto() is needed */
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int movetoTarget; /* Argument to the deferred sqliteBtreeMoveto() */
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Btree *pBt; /* Separate file holding temporary table */
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int nData; /* Number of bytes in pData */
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char *pData; /* Data for a NEW or OLD pseudo-table */
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int iKey; /* Key for the NEW or OLD pseudo-table row */
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};
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typedef struct Cursor Cursor;
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/*
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** A sorter builds a list of elements to be sorted. Each element of
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** the list is an instance of the following structure.
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*/
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typedef struct Sorter Sorter;
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struct Sorter {
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int nKey; /* Number of bytes in the key */
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char *zKey; /* The key by which we will sort */
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int nData; /* Number of bytes in the data */
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char *pData; /* The data associated with this key */
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Sorter *pNext; /* Next in the list */
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};
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/*
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** Number of buckets used for merge-sort.
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*/
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#define NSORT 30
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/*
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** Number of bytes of string storage space available to each stack
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** layer without having to malloc. NBFS is short for Number of Bytes
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** For Strings.
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*/
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#define NBFS 32
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/*
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** A single level of the stack or a single memory cell
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** is an instance of the following structure.
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*/
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struct Mem {
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int i; /* Integer value */
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int n; /* Number of characters in string value, including '\0' */
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int flags; /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
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double r; /* Real value */
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char *z; /* String value */
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char zShort[NBFS]; /* Space for short strings */
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};
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typedef struct Mem Mem;
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/*
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** Allowed values for Mem.flags
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*/
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#define MEM_Null 0x0001 /* Value is NULL */
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#define MEM_Str 0x0002 /* Value is a string */
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#define MEM_Int 0x0004 /* Value is an integer */
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#define MEM_Real 0x0008 /* Value is a real number */
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#define MEM_Dyn 0x0010 /* Need to call sqliteFree() on Mem.z */
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#define MEM_Static 0x0020 /* Mem.z points to a static string */
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#define MEM_Ephem 0x0040 /* Mem.z points to an ephemeral string */
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#define MEM_Short 0x0080 /* Mem.z points to Mem.zShort */
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/* The following MEM_ value appears only in AggElem.aMem.s.flag fields.
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** It indicates that the corresponding AggElem.aMem.z points to a
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** aggregate function context that needs to be finalized.
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*/
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#define MEM_AggCtx 0x0100 /* Mem.z points to an agg function context */
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/*
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** The "context" argument for a installable function. A pointer to an
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** instance of this structure is the first argument to the routines used
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** implement the SQL functions.
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**
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** There is a typedef for this structure in sqlite.h. So all routines,
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** even the public interface to SQLite, can use a pointer to this structure.
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** But this file is the only place where the internal details of this
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** structure are known.
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**
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** This structure is defined inside of vdbe.c because it uses substructures
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** (Mem) which are only defined there.
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*/
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struct sqlite_func {
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FuncDef *pFunc; /* Pointer to function information. MUST BE FIRST */
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Mem s; /* The return value is stored here */
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void *pAgg; /* Aggregate context */
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u8 isError; /* Set to true for an error */
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u8 isStep; /* Current in the step function */
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int cnt; /* Number of times that the step function has been called */
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};
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/*
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** An Agg structure describes an Aggregator. Each Agg consists of
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** zero or more Aggregator elements (AggElem). Each AggElem contains
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** a key and one or more values. The values are used in processing
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** aggregate functions in a SELECT. The key is used to implement
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** the GROUP BY clause of a select.
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*/
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typedef struct Agg Agg;
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typedef struct AggElem AggElem;
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struct Agg {
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int nMem; /* Number of values stored in each AggElem */
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AggElem *pCurrent; /* The AggElem currently in focus */
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HashElem *pSearch; /* The hash element for pCurrent */
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Hash hash; /* Hash table of all aggregate elements */
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FuncDef **apFunc; /* Information about aggregate functions */
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};
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struct AggElem {
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char *zKey; /* The key to this AggElem */
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int nKey; /* Number of bytes in the key, including '\0' at end */
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Mem aMem[1]; /* The values for this AggElem */
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};
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/*
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** A Set structure is used for quick testing to see if a value
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** is part of a small set. Sets are used to implement code like
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** this:
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** x.y IN ('hi','hoo','hum')
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*/
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typedef struct Set Set;
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struct Set {
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Hash hash; /* A set is just a hash table */
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HashElem *prev; /* Previously accessed hash elemen */
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};
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/*
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** A Keylist is a bunch of keys into a table. The keylist can
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** grow without bound. The keylist stores the ROWIDs of database
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** records that need to be deleted or updated.
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*/
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typedef struct Keylist Keylist;
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struct Keylist {
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int nKey; /* Number of slots in aKey[] */
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int nUsed; /* Next unwritten slot in aKey[] */
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int nRead; /* Next unread slot in aKey[] */
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Keylist *pNext; /* Next block of keys */
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int aKey[1]; /* One or more keys. Extra space allocated as needed */
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};
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/*
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** A Context stores the last insert rowid, the last statement change count,
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** and the current statement change count (i.e. changes since last statement).
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** Elements of Context structure type make up the ContextStack, which is
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** updated by the ContextPush and ContextPop opcodes (used by triggers)
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*/
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typedef struct Context Context;
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struct Context {
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int lastRowid; /* Last insert rowid (from db->lastRowid) */
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int lsChange; /* Last statement change count (from db->lsChange) */
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int csChange; /* Current statement change count (from db->csChange) */
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};
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/*
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** An instance of the virtual machine. This structure contains the complete
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** state of the virtual machine.
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**
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** The "sqlite_vm" structure pointer that is returned by sqlite_compile()
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** is really a pointer to an instance of this structure.
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*/
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struct Vdbe {
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sqlite *db; /* The whole database */
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Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */
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FILE *trace; /* Write an execution trace here, if not NULL */
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int nOp; /* Number of instructions in the program */
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int nOpAlloc; /* Number of slots allocated for aOp[] */
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Op *aOp; /* Space to hold the virtual machine's program */
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int nLabel; /* Number of labels used */
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int nLabelAlloc; /* Number of slots allocated in aLabel[] */
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int *aLabel; /* Space to hold the labels */
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Mem *aStack; /* The operand stack, except string values */
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Mem *pTos; /* Top entry in the operand stack */
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char **zArgv; /* Text values used by the callback */
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char **azColName; /* Becomes the 4th parameter to callbacks */
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int nCursor; /* Number of slots in aCsr[] */
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Cursor *aCsr; /* One element of this array for each open cursor */
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Sorter *pSort; /* A linked list of objects to be sorted */
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FILE *pFile; /* At most one open file handler */
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int nField; /* Number of file fields */
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char **azField; /* Data for each file field */
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int nVar; /* Number of entries in azVariable[] */
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char **azVar; /* Values for the OP_Variable opcode */
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int *anVar; /* Length of each value in azVariable[] */
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u8 *abVar; /* TRUE if azVariable[i] needs to be sqliteFree()ed */
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char *zLine; /* A single line from the input file */
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int nLineAlloc; /* Number of spaces allocated for zLine */
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int magic; /* Magic number for sanity checking */
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int nMem; /* Number of memory locations currently allocated */
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Mem *aMem; /* The memory locations */
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Agg agg; /* Aggregate information */
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int nSet; /* Number of sets allocated */
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Set *aSet; /* An array of sets */
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int nCallback; /* Number of callbacks invoked so far */
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Keylist *pList; /* A list of ROWIDs */
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int keylistStackDepth; /* The size of the "keylist" stack */
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Keylist **keylistStack; /* The stack used by opcodes ListPush & ListPop */
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int contextStackDepth; /* The size of the "context" stack */
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Context *contextStack; /* Stack used by opcodes ContextPush & ContextPop*/
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int pc; /* The program counter */
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int rc; /* Value to return */
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unsigned uniqueCnt; /* Used by OP_MakeRecord when P2!=0 */
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int errorAction; /* Recovery action to do in case of an error */
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int undoTransOnError; /* If error, either ROLLBACK or COMMIT */
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int inTempTrans; /* True if temp database is transactioned */
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int returnStack[100]; /* Return address stack for OP_Gosub & OP_Return */
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int returnDepth; /* Next unused element in returnStack[] */
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int nResColumn; /* Number of columns in one row of the result set */
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char **azResColumn; /* Values for one row of result */
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int popStack; /* Pop the stack this much on entry to VdbeExec() */
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char *zErrMsg; /* Error message written here */
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u8 explain; /* True if EXPLAIN present on SQL command */
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};
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/*
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** The following are allowed values for Vdbe.magic
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*/
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#define VDBE_MAGIC_INIT 0x26bceaa5 /* Building a VDBE program */
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#define VDBE_MAGIC_RUN 0xbdf20da3 /* VDBE is ready to execute */
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#define VDBE_MAGIC_HALT 0x519c2973 /* VDBE has completed execution */
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#define VDBE_MAGIC_DEAD 0xb606c3c8 /* The VDBE has been deallocated */
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/*
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** Function prototypes
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*/
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void sqliteVdbeCleanupCursor(Cursor*);
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void sqliteVdbeSorterReset(Vdbe*);
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void sqliteVdbeAggReset(Agg*);
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void sqliteVdbeKeylistFree(Keylist*);
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void sqliteVdbePopStack(Vdbe*,int);
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int sqliteVdbeCursorMoveto(Cursor*);
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int sqliteVdbeByteSwap(int);
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#if !defined(NDEBUG) || defined(VDBE_PROFILE)
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void sqliteVdbePrintOp(FILE*, int, Op*);
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#endif
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