sqliteint.h

sqlite-3.4.1,嵌入式数据库.是一个功能强大的开源数据库,给学习和研发以及小型公司的发展带来了全所未有的好处.

struct WhereLevel {
  int iFrom;            /* Which entry in the FROM clause */
  int flags;            /* Flags associated with this level */
  int iMem;             /* First memory cell used by this level */
  int iLeftJoin;        /* Memory cell used to implement LEFT OUTER JOIN */
  Index *pIdx;          /* Index used.  NULL if no index */
  int iTabCur;          /* The VDBE cursor used to access the table */
  int iIdxCur;          /* The VDBE cursor used to acesss pIdx */
  int brk;              /* Jump here to break out of the loop */
  int nxt;              /* Jump here to start the next IN combination */
  int cont;             /* Jump here to continue with the next loop cycle */
  int top;              /* First instruction of interior of the loop */
  int op, p1, p2;       /* Opcode used to terminate the loop */
  int nEq;              /* Number of == or IN constraints on this loop */
  int nIn;              /* Number of IN operators constraining this loop */
  struct InLoop {
    int iCur;              /* The VDBE cursor used by this IN operator */
    int topAddr;           /* Top of the IN loop */
  } *aInLoop;           /* Information about each nested IN operator */
  sqlite3_index_info *pBestIdx;  /* Index information for this level */

  /* The following field is really not part of the current level.  But
  ** we need a place to cache index information for each table in the
  ** FROM clause and the WhereLevel structure is a convenient place.
  */
  sqlite3_index_info *pIdxInfo;  /* Index info for n-th source table */
};

/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second
** half does the tail of the WHERE loop.  An instance of
** this structure is returned by the first half and passed
** into the second half to give some continuity.
*/
struct WhereInfo {
  Parse *pParse;
  SrcList *pTabList;   /* List of tables in the join */
  int iTop;            /* The very beginning of the WHERE loop */
  int iContinue;       /* Jump here to continue with next record */
  int iBreak;          /* Jump here to break out of the loop */
  int nLevel;          /* Number of nested loop */
  sqlite3_index_info **apInfo;  /* Array of pointers to index info structures */
  WhereLevel a[1];     /* Information about each nest loop in the WHERE */
};

/*
** A NameContext defines a context in which to resolve table and column
** names.  The context consists of a list of tables (the pSrcList) field and
** a list of named expression (pEList).  The named expression list may
** be NULL.  The pSrc corresponds to the FROM clause of a SELECT or
** to the table being operated on by INSERT, UPDATE, or DELETE.  The
** pEList corresponds to the result set of a SELECT and is NULL for
** other statements.
**
** NameContexts can be nested.  When resolving names, the inner-most 
** context is searched first.  If no match is found, the next outer
** context is checked.  If there is still no match, the next context
** is checked.  This process continues until either a match is found
** or all contexts are check.  When a match is found, the nRef member of
** the context containing the match is incremented. 
**
** Each subquery gets a new NameContext.  The pNext field points to the
** NameContext in the parent query.  Thus the process of scanning the
** NameContext list corresponds to searching through successively outer
** subqueries looking for a match.
*/
struct NameContext {
  Parse *pParse;       /* The parser */
  SrcList *pSrcList;   /* One or more tables used to resolve names */
  ExprList *pEList;    /* Optional list of named expressions */
  int nRef;            /* Number of names resolved by this context */
  int nErr;            /* Number of errors encountered while resolving names */
  u8 allowAgg;         /* Aggregate functions allowed here */
  u8 hasAgg;           /* True if aggregates are seen */
  u8 isCheck;          /* True if resolving names in a CHECK constraint */
  int nDepth;          /* Depth of subquery recursion. 1 for no recursion */
  AggInfo *pAggInfo;   /* Information about aggregates at this level */
  NameContext *pNext;  /* Next outer name context.  NULL for outermost */
};

/*
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
** limit and nOffset to the value of the offset (or 0 if there is not
** offset).  But later on, nLimit and nOffset become the memory locations
** in the VDBE that record the limit and offset counters.
**
** addrOpenEphm[] entries contain the address of OP_OpenEphemeral opcodes.
** These addresses must be stored so that we can go back and fill in
** the P3_KEYINFO and P2 parameters later.  Neither the KeyInfo nor
** the number of columns in P2 can be computed at the same time
** as the OP_OpenEphm instruction is coded because not
** enough information about the compound query is known at that point.
** The KeyInfo for addrOpenTran[0] and [1] contains collating sequences
** for the result set.  The KeyInfo for addrOpenTran[2] contains collating
** sequences for the ORDER BY clause.
*/
struct Select {
  ExprList *pEList;      /* The fields of the result */
  u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
  u8 isDistinct;         /* True if the DISTINCT keyword is present */
  u8 isResolved;         /* True once sqlite3SelectResolve() has run. */
  u8 isAgg;              /* True if this is an aggregate query */
  u8 usesEphm;           /* True if uses an OpenEphemeral opcode */
  u8 disallowOrderBy;    /* Do not allow an ORDER BY to be attached if TRUE */
  char affinity;         /* MakeRecord with this affinity for SRT_Set */
  SrcList *pSrc;         /* The FROM clause */
  Expr *pWhere;          /* The WHERE clause */
  ExprList *pGroupBy;    /* The GROUP BY clause */
  Expr *pHaving;         /* The HAVING clause */
  ExprList *pOrderBy;    /* The ORDER BY clause */
  Select *pPrior;        /* Prior select in a compound select statement */
  Select *pRightmost;    /* Right-most select in a compound select statement */
  Expr *pLimit;          /* LIMIT expression. NULL means not used. */
  Expr *pOffset;         /* OFFSET expression. NULL means not used. */
  int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
  int addrOpenEphm[3];   /* OP_OpenEphem opcodes related to this select */
};

/*
** The results of a select can be distributed in several ways.
*/
#define SRT_Union        1  /* Store result as keys in an index */
#define SRT_Except       2  /* Remove result from a UNION index */
#define SRT_Discard      3  /* Do not save the results anywhere */

/* The ORDER BY clause is ignored for all of the above */
#define IgnorableOrderby(X) (X<=SRT_Discard)

#define SRT_Callback     4  /* Invoke a callback with each row of result */
#define SRT_Mem          5  /* Store result in a memory cell */
#define SRT_Set          6  /* Store non-null results as keys in an index */
#define SRT_Table        7  /* Store result as data with an automatic rowid */
#define SRT_EphemTab     8  /* Create transient tab and store like SRT_Table */
#define SRT_Subroutine   9  /* Call a subroutine to handle results */
#define SRT_Exists      10  /* Store 1 if the result is not empty */

/*
** An SQL parser context.  A copy of this structure is passed through
** the parser and down into all the parser action routine in order to
** carry around information that is global to the entire parse.
**
** The structure is divided into two parts.  When the parser and code
** generate call themselves recursively, the first part of the structure
** is constant but the second part is reset at the beginning and end of
** each recursion.
**
** The nTableLock and aTableLock variables are only used if the shared-cache 
** feature is enabled (if sqlite3Tsd()->useSharedData is true). They are
** used to store the set of table-locks required by the statement being
** compiled. Function sqlite3TableLock() is used to add entries to the
** list.
*/
struct Parse {
  sqlite3 *db;         /* The main database structure */
  int rc;              /* Return code from execution */
  char *zErrMsg;       /* An error message */
  Vdbe *pVdbe;         /* An engine for executing database bytecode */
  u8 colNamesSet;      /* TRUE after OP_ColumnName has been issued to pVdbe */
  u8 nameClash;        /* A permanent table name clashes with temp table name */
  u8 checkSchema;      /* Causes schema cookie check after an error */
  u8 nested;           /* Number of nested calls to the parser/code generator */
  u8 parseError;       /* True after a parsing error.  Ticket #1794 */
  int nErr;            /* Number of errors seen */
  int nTab;            /* Number of previously allocated VDBE cursors */
  int nMem;            /* Number of memory cells used so far */
  int nSet;            /* Number of sets used so far */
  int ckOffset;        /* Stack offset to data used by CHECK constraints */
  u32 writeMask;       /* Start a write transaction on these databases */
  u32 cookieMask;      /* Bitmask of schema verified databases */
  int cookieGoto;      /* Address of OP_Goto to cookie verifier subroutine */
  int cookieValue[SQLITE_MAX_ATTACHED+2];  /* Values of cookies to verify */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nTableLock;        /* Number of locks in aTableLock */
  TableLock *aTableLock; /* Required table locks for shared-cache mode */
#endif

  /* Above is constant between recursions.  Below is reset before and after
  ** each recursion */

  int nVar;            /* Number of '?' variables seen in the SQL so far */
  int nVarExpr;        /* Number of used slots in apVarExpr[] */
  int nVarExprAlloc;   /* Number of allocated slots in apVarExpr[] */
  Expr **apVarExpr;    /* Pointers to :aaa and $aaaa wildcard expressions */
  u8 explain;          /* True if the EXPLAIN flag is found on the query */
  Token sErrToken;     /* The token at which the error occurred */
  Token sNameToken;    /* Token with unqualified schema object name */
  Token sLastToken;    /* The last token parsed */
  const char *zSql;    /* All SQL text */
  const char *zTail;   /* All SQL text past the last semicolon parsed */
  Table *pNewTable;    /* A table being constructed by CREATE TABLE */
  Trigger *pNewTrigger;     /* Trigger under construct by a CREATE TRIGGER */
  TriggerStack *trigStack;  /* Trigger actions being coded */
  const char *zAuthContext; /* The 6th parameter to db->xAuth callbacks */
#ifndef SQLITE_OMIT_VIRTUALTABLE
  Token sArg;                /* Complete text of a module argument */
  u8 declareVtab;            /* True if inside sqlite3_declare_vtab() */
  Table *pVirtualLock;       /* Require virtual table lock on this table */
#endif
#if SQLITE_MAX_EXPR_DEPTH>0
  int nHeight;            /* Expression tree height of current sub-select */
#endif
};

#ifdef SQLITE_OMIT_VIRTUALTABLE
  #define IN_DECLARE_VTAB 0
#else
  #define IN_DECLARE_VTAB (pParse->declareVtab)
#endif

/*
** An instance of the following structure can be declared on a stack and used
** to save the Parse.zAuthContext value so that it can be restored later.
*/
struct AuthContext {
  const char *zAuthContext;   /* Put saved Parse.zAuthContext here */
  Parse *pParse;              /* The Parse structure */
};

/*
** Bitfield flags for P2 value in OP_Insert and OP_Delete
*/
#define OPFLAG_NCHANGE   1    /* Set to update db->nChange */
#define OPFLAG_LASTROWID 2    /* Set to update db->lastRowid */
#define OPFLAG_ISUPDATE  4    /* This OP_Insert is an sql UPDATE */
#define OPFLAG_APPEND    8    /* This is likely to be an append */

/*
 * Each trigger present in the database schema is stored as an instance of
 * struct Trigger. 
 *
 * Pointers to instances of struct Trigger are stored in two ways.
 * 1. In the "trigHash" hash table (part of the sqlite3* that represents the 
 *    database). This allows Trigger structures to be retrieved by name.
 * 2. All triggers associated with a single table form a linked list, using the
 *    pNext member of struct Trigger. A pointer to the first element of the
 *    linked list is stored as the "pTrigger" member of the associated
 *    struct Table.
 *
 * The "step_list" member points to the first element of a linked list
 * containing the SQL statements specified as the trigger program.
 */
struct Trigger {
  char *name;             /* The name of the trigger                        */
  char *table;            /* The table or view to which the trigger applies */
  u8 op;                  /* One of TK_DELETE, TK_UPDATE, TK_INSERT         */
  u8 tr_tm;               /* One of TRIGGER_BEFORE, TRIGGER_AFTER */
  Expr *pWhen;            /* The WHEN clause of the expresion (may be NULL) */
  IdList *pColumns;       /* If this is an UPDATE OF <column-list> trigger,
                             the <column-list> is stored here */
  Token nameToken;        /* Token containing zName. Use during parsing only */
  Schema *pSchema;        /* Schema containing the trigger */
  Schema *pTabSchema;     /* Schema containing the table */
  TriggerStep *step_list; /* Link list of trigger program steps             */
  Trigger *pNext;         /* Next trigger associated with the table */
};

/*
** A trigger is either a BEFORE or an AFTER trigger.  The following constants
** determine which. 
**
** If there are multiple triggers, you might of some BEFORE and some AFTER.
** In that cases, the constants below can be ORed together.
*/
#define TRIGGER_BEFORE  1
#define TRIGGER_AFTER   2

/*
 * An instance of struct TriggerStep is used to store a single SQL statement
 * that is a part of a trigger-program. 
 *
 * Instances of struct TriggerStep are stored in a singly linked list (linked
 * using the "pNext" member) referenced by the "step_list" member of the 
 * associated struct Trigger instance. The first element of the linked list is
 * the first step of the trigger-program.
 * 
 * The "op" member indicates whether this is a "DELETE", "INSERT", "UPDATE" or
 * "SELECT" statement. The meanings of the other members is determined by the 
 * value of "op" as follows:
 *
 * (op == TK_INSERT)
 * orconf    -> stores the ON CONFLICT algorithm
 * pSelect   -> If this is an INSERT INTO ... SELECT ... statement, then
 *              this s