parsenodes.h

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * parsenodes.h
 *	  definitions for parse tree nodes
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.292.2.1 2005/11/22 18:23:28 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef PARSENODES_H
#define PARSENODES_H

#include "nodes/primnodes.h"


/* Possible sources of a Query */
typedef enum QuerySource
{
	QSRC_ORIGINAL,				/* original parsetree (explicit query) */
	QSRC_PARSER,				/* added by parse analysis */
	QSRC_INSTEAD_RULE,			/* added by unconditional INSTEAD rule */
	QSRC_QUAL_INSTEAD_RULE,		/* added by conditional INSTEAD rule */
	QSRC_NON_INSTEAD_RULE		/* added by non-INSTEAD rule */
} QuerySource;

/*
 * Grantable rights are encoded so that we can OR them together in a bitmask.
 * The present representation of AclItem limits us to 16 distinct rights,
 * even though AclMode is defined as uint32.  See utils/acl.h.
 *
 * Caution: changing these codes breaks stored ACLs, hence forces initdb.
 */
typedef uint32 AclMode;			/* a bitmask of privilege bits */

#define ACL_INSERT		(1<<0)	/* for relations */
#define ACL_SELECT		(1<<1)
#define ACL_UPDATE		(1<<2)
#define ACL_DELETE		(1<<3)
#define ACL_RULE		(1<<4)
#define ACL_REFERENCES	(1<<5)
#define ACL_TRIGGER		(1<<6)
#define ACL_EXECUTE		(1<<7)	/* for functions */
#define ACL_USAGE		(1<<8)	/* for languages and namespaces */
#define ACL_CREATE		(1<<9)	/* for namespaces and databases */
#define ACL_CREATE_TEMP (1<<10) /* for databases */
#define N_ACL_RIGHTS	11		/* 1 plus the last 1<<x */
#define ACL_NO_RIGHTS	0
/* Currently, SELECT ... FOR UPDATE/FOR SHARE requires UPDATE privileges */
#define ACL_SELECT_FOR_UPDATE	ACL_UPDATE


/*****************************************************************************
 *	Query Tree
 *****************************************************************************/

/*
 * Query -
 *	  all statements are turned into a Query tree (via transformStmt)
 *	  for further processing by the optimizer
 *
 *	  utility statements (i.e. non-optimizable statements) have the
 *	  utilityStmt field set, and the Query itself is mostly dummy.
 */
typedef struct Query
{
	NodeTag		type;

	CmdType		commandType;	/* select|insert|update|delete|utility */

	QuerySource querySource;	/* where did I come from? */

	bool		canSetTag;		/* do I set the command result tag? */

	Node	   *utilityStmt;	/* non-null if this is a non-optimizable
								 * statement */

	int			resultRelation; /* target relation (index into rtable) */

	RangeVar   *into;			/* target relation for SELECT INTO */
	bool		intoHasOids;	/* should target relation contain OIDs? */

	bool		hasAggs;		/* has aggregates in tlist or havingQual */
	bool		hasSubLinks;	/* has subquery SubLink */

	List	   *rtable;			/* list of range table entries */
	FromExpr   *jointree;		/* table join tree (FROM and WHERE clauses) */

	List	   *rowMarks;		/* integer list of RT indexes of relations
								 * that are selected FOR UPDATE/SHARE */

	bool		forUpdate;		/* true if rowMarks are FOR UPDATE, false if
								 * they are FOR SHARE */
	bool		rowNoWait;		/* FOR UPDATE/SHARE NOWAIT option */

	List	   *targetList;		/* target list (of TargetEntry) */

	List	   *groupClause;	/* a list of GroupClause's */

	Node	   *havingQual;		/* qualifications applied to groups */

	List	   *distinctClause; /* a list of SortClause's */

	List	   *sortClause;		/* a list of SortClause's */

	Node	   *limitOffset;	/* # of result tuples to skip */
	Node	   *limitCount;		/* # of result tuples to return */

	Node	   *setOperations;	/* set-operation tree if this is top level of
								 * a UNION/INTERSECT/EXCEPT query */

	/*
	 * If the resultRelation turns out to be the parent of an inheritance
	 * tree, the planner will add all the child tables to the rtable and store
	 * a list of the rtindexes of all the result relations here. This is done
	 * at plan time, not parse time, since we don't want to commit to the
	 * exact set of child tables at parse time.  This field ought to go in
	 * some sort of TopPlan plan node, not in the Query.
	 */
	List	   *resultRelations;	/* integer list of RT indexes, or NIL */
} Query;


/****************************************************************************
 *	Supporting data structures for Parse Trees
 *
 *	Most of these node types appear in raw parsetrees output by the grammar,
 *	and get transformed to something else by the analyzer.	A few of them
 *	are used as-is in transformed querytrees.
 ****************************************************************************/

/*
 * TypeName - specifies a type in definitions
 *
 * For TypeName structures generated internally, it is often easier to
 * specify the type by OID than by name.  If "names" is NIL then the
 * actual type OID is given by typeid, otherwise typeid is unused.
 *
 * If pct_type is TRUE, then names is actually a field name and we look up
 * the type of that field.	Otherwise (the normal case), names is a type
 * name possibly qualified with schema and database name.
 */
typedef struct TypeName
{
	NodeTag		type;
	List	   *names;			/* qualified name (list of Value strings) */
	Oid			typeid;			/* type identified by OID */
	bool		timezone;		/* timezone specified? */
	bool		setof;			/* is a set? */
	bool		pct_type;		/* %TYPE specified? */
	int32		typmod;			/* type modifier */
	List	   *arrayBounds;	/* array bounds */
} TypeName;

/*
 * ColumnRef - specifies a reference to a column, or possibly a whole tuple
 *
 *		The "fields" list must be nonempty; its last component may be "*"
 *		instead of a regular field name.
 *
 * Note: any array subscripting or selection of fields from composite columns
 * is represented by an A_Indirection node above the ColumnRef.  However,
 * for simplicity in the normal case, initial field selection from a table
 * name is represented within ColumnRef and not by adding A_Indirection.
 */
typedef struct ColumnRef
{
	NodeTag		type;
	List	   *fields;			/* field names (list of Value strings) */
} ColumnRef;

/*
 * ParamRef - specifies a $n parameter reference
 */
typedef struct ParamRef
{
	NodeTag		type;
	int			number;			/* the number of the parameter */
} ParamRef;

/*
 * A_Expr - infix, prefix, and postfix expressions
 */
typedef enum A_Expr_Kind
{
	AEXPR_OP,					/* normal operator */
	AEXPR_AND,					/* booleans - name field is unused */
	AEXPR_OR,
	AEXPR_NOT,
	AEXPR_OP_ANY,				/* scalar op ANY (array) */
	AEXPR_OP_ALL,				/* scalar op ALL (array) */
	AEXPR_DISTINCT,				/* IS DISTINCT FROM - name must be "=" */
	AEXPR_NULLIF,				/* NULLIF - name must be "=" */
	AEXPR_OF					/* IS (not) OF - name must be "=" or "!=" */
} A_Expr_Kind;

typedef struct A_Expr
{
	NodeTag		type;
	A_Expr_Kind kind;			/* see above */
	List	   *name;			/* possibly-qualified name of operator */
	Node	   *lexpr;			/* left argument, or NULL if none */
	Node	   *rexpr;			/* right argument, or NULL if none */
} A_Expr;

/*
 * A_Const - a constant expression
 */
typedef struct A_Const
{
	NodeTag		type;
	Value		val;			/* the value (with the tag) */
	TypeName   *typename;		/* typecast */
} A_Const;

/*
 * TypeCast - a CAST expression
 *
 * NOTE: for mostly historical reasons, A_Const parsenodes contain
 * room for a TypeName; we only generate a separate TypeCast node if the
 * argument to be casted is not a constant.  In theory either representation
 * would work, but it is convenient to have the target type immediately
 * available while resolving a constant's datatype.
 */
typedef struct TypeCast
{
	NodeTag		type;
	Node	   *arg;			/* the expression being casted */
	TypeName   *typename;		/* the target type */
} TypeCast;

/*
 * FuncCall - a function or aggregate invocation
 *
 * agg_star indicates we saw a 'foo(*)' construct, while agg_distinct
 * indicates we saw 'foo(DISTINCT ...)'.  In either case, the construct
 * *must* be an aggregate call.  Otherwise, it might be either an
 * aggregate or some other kind of function.
 */
typedef struct FuncCall
{
	NodeTag		type;
	List	   *funcname;		/* qualified name of function */
	List	   *args;			/* the arguments (list of exprs) */
	bool		agg_star;		/* argument was really '*' */
	bool		agg_distinct;	/* arguments were labeled DISTINCT */
} FuncCall;

/*
 * A_Indices - array reference or bounds ([lidx:uidx] or [uidx])
 */
typedef struct A_Indices
{
	NodeTag		type;
	Node	   *lidx;			/* could be NULL */
	Node	   *uidx;
} A_Indices;

/*
 * A_Indirection - select a field and/or array element from an expression
 *
 * The indirection list can contain both A_Indices nodes (representing
 * subscripting) and string Value nodes (representing field selection
 * --- the string value is the name of the field to select).  For example,
 * a complex selection operation like
 *				(foo).field1[42][7].field2
 * would be represented with a single A_Indirection node having a 4-element
 * indirection list.
 *
 * Note: as of Postgres 8.0, we don't support arrays of composite values,
 * so cases in which a field select follows a subscript aren't actually
 * semantically legal.	However the parser is prepared to handle such.
 */
typedef struct A_Indirection
{
	NodeTag		type;
	Node	   *arg;			/* the thing being selected from */
	List	   *indirection;	/* subscripts and/or field names */
} A_Indirection;

/*
 * ResTarget -
 *	  result target (used in target list of pre-transformed parse trees)
 *
 * In a SELECT or INSERT target list, 'name' is the column label from an
 * 'AS ColumnLabel' clause, or NULL if there was none, and 'val' is the
 * value expression itself.  The 'indirection' field is not used.
 *
 * INSERT has a second ResTarget list which is the target-column-names list.
 * Here, 'val' is not used, 'name' is the name of the destination column,
 * and 'indirection' stores any subscripts attached to the destination.
 *
 * In an UPDATE target list, 'name' is the name of the destination column,
 * 'indirection' stores any subscripts attached to the destination, and
 * 'val' is the expression to assign.
 *
 * See A_Indirection for more info about what can appear in 'indirection'.
 */
typedef struct ResTarget
{
	NodeTag		type;
	char	   *name;			/* column name or NULL */
	List	   *indirection;	/* subscripts and field names, or NIL */
	Node	   *val;			/* the value expression to compute or assign */
} ResTarget;

/*
 * SortBy - for ORDER BY clause
 */
#define SORTBY_ASC		1
#define SORTBY_DESC		2
#define SORTBY_USING	3

typedef struct SortBy
{
	NodeTag		type;
	int			sortby_kind;	/* see codes above */
	List	   *useOp;			/* name of op to use, if SORTBY_USING */
	Node	   *node;			/* expression to sort on */
} SortBy;

/*
 * RangeSubselect - subquery appearing in a FROM clause
 */
typedef struct RangeSubselect
{
	NodeTag		type;
	Node	   *subquery;		/* the untransformed sub-select clause */
	Alias	   *alias;			/* table alias & optional column aliases */
} RangeSubselect;

/*
 * RangeFunction - function call appearing in a FROM clause
 */
typedef struct RangeFunction
{
	NodeTag		type;
	Node	   *funccallnode;	/* untransformed function call tree */
	Alias	   *alias;			/* table alias & optional column aliases */
	List	   *coldeflist;		/* list of ColumnDef nodes for runtime
								 * assignment of RECORD TupleDesc */
} RangeFunction;

/*
 * ColumnDef - column definition (used in various creates)
 *
 * If the column has a default value, we may have the value expression
 * in either "raw" form (an untransformed parse tree) or "cooked" form
 * (the nodeToString representation of an executable expression tree),
 * depending on how this ColumnDef node was created (by parsing, or by
 * inheritance from an existing relation).	We should never have both
 * in the same node!
 *
 * The constraints list may contain a CONSTR_DEFAULT item in a raw
 * parsetree produced by gram.y, but transformCreateStmt will remove
 * the item and set raw_default instead.  CONSTR_DEFAULT items
 * should not appear in any subsequent processing.
 *
 * The "support" field, if not null, denotes a supporting relation that
 * should be linked by an internal dependency to the column.  Currently
 * this is only used to link a SERIAL column's sequence to the column.
 */
typedef struct ColumnDef
{
	NodeTag		type;
	char	   *colname;		/* name of column */
	TypeName   *typename;		/* type of column */
	int			inhcount;		/* number of times column is inherited */
	bool		is_local;		/* column has local (non-inherited) def'n */
	bool		is_not_null;	/* NOT NULL constraint specified? */
	Node	   *raw_default;	/* default value (untransformed parse tree) */
	char	   *cooked_default; /* nodeToString representation */
	List	   *constraints;	/* other constraints on column */
	RangeVar   *support;		/* supporting relation, if any */
} ColumnDef;

/*
 * inhRelation - Relations a CREATE TABLE is to inherit attributes of
 */
typedef struct InhRelation
{
	NodeTag		type;
	RangeVar   *relation;
	bool		including_defaults;
} InhRelation;

/*
 * IndexElem - index parameters (used in CREATE INDEX)
 *
 * For a plain index attribute, 'name' is the name of the table column to
 * index, and 'expr' is NULL.  For an index expression, 'name' is NULL and
 * 'expr' is the expression tree.
 */
typedef struct IndexElem
{
	NodeTag		type;
	char	   *name;			/* name of attribute to index, or NULL */
	Node	   *expr;			/* expression to index, or NULL */
	List	   *opclass;		/* name of desired opclass; NIL = default */
} IndexElem;

/*
 * DefElem -
 *	  a definition (used in definition lists in the form of defname = arg)
 */
typedef struct DefElem
{
	NodeTag		type;
	char	   *defname;
	Node	   *arg;			/* a (Value *) or a (TypeName *) */
} DefElem;

/*
 * LockingClause - raw representation of FOR UPDATE/SHARE options
 *
 * Note: lockedRels == NIL means "all relations in query".	Otherwise it
 * is a list of String nodes giving relation eref names.
 */
typedef struct LockingClause
{
	NodeTag		type;
	List	   *lockedRels;		/* FOR UPDATE or FOR SHARE relations */
	bool		forUpdate;		/* true = FOR UPDATE, false = FOR SHARE */
	bool		nowait;			/* NOWAIT option */
} LockingClause;


/****************************************************************************
 *	Nodes for a Query tree
 ****************************************************************************/

/*--------------------
 * RangeTblEntry -
 *	  A range table is a List of RangeTblEntry nodes.
 *
 *	  A range table entry may represent a plain relation, a sub-select in
 *	  FROM, or the result of a JOIN clause.  (Only explicit JOIN syntax
 *	  produces an RTE, not the implicit join resulting from multiple FROM
 *	  items.  This is because we only need the RTE to deal with SQL features
 *	  like outer joins and join-output-column aliasing.)  Other special
 *	  RTE types also exist, as indicated by RTEKind.
 *
 *	  alias is an Alias node representing the AS alias-clause attached to the
 *	  FROM expression, or NULL if no clause.
 *
 *	  eref is the table reference name and column reference names (either
 *	  real or aliases).  Note that system columns (OID etc) are not included
 *	  in the column list.
 *	  eref->aliasname is required to be present, and should generally be used
 *	  to identify the RTE for error messages etc.
 *
 *	  In RELATION RTEs, the colnames in both alias and eref are indexed by
 *	  physical attribute number; this means there must be colname entries for
 *	  dropped columns.	When building an RTE we insert empty strings ("") for
 *	  dropped columns.	Note however that a stored rule may have nonempty
 *	  colnames for columns dropped since the rule was created (and for that
 *	  matter the colnames might be out of date due to column renamings).
 *	  The same comments apply to FUNCTION RTEs when the function's return type
 *	  is a named composite type.
 *
 *	  In JOIN RTEs, the colnames in both alias and eref are one-to-one with
 *	  joinaliasvars entries.  A JOIN RTE will omit columns of its inputs when
 *	  those columns are known to be dropped at parse time.	Again, however,
 *	  a stored rule might contain entries for columns dropped since the rule
 *	  was created.	(This is only possible for columns not actually referenced
 *	  in the rule.)  When loading a stored rule, we replace the joinaliasvars
 *	  items for any such columns with NULL Consts.	(We can't simply delete