parsenodes.h

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/*-------------------------------------------------------------------------
 *
 * parsenodes.h
 *	  definitions for parse tree nodes
 *
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $Id: parsenodes.h,v 1.248 2003/09/17 04:25:29 ishii 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;


/*****************************************************************************
 *	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.
 */
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		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 */

	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 */

	/* internal to planner */
	List	   *base_rel_list;	/* list of base-relation RelOptInfos */
	List	   *other_rel_list; /* list of other 1-relation RelOptInfos */
	List	   *join_rel_list;	/* list of join-relation RelOptInfos */
	List	   *equi_key_list;	/* list of lists of equijoined
								 * PathKeyItems */
	List	   *in_info_list;	/* list of InClauseInfos */
	List	   *query_pathkeys; /* desired pathkeys for query_planner() */
	bool		hasJoinRTEs;	/* true if any RTEs are RTE_JOIN kind */
} 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 field name.  Subscripts are optional.
 */
typedef struct ColumnRef
{
	NodeTag		type;
	List	   *fields;			/* field names (list of Value strings) */
	List	   *indirection;	/* subscripts (list of A_Indices) */
} ColumnRef;

/*
 * ParamRef - specifies a parameter reference
 *
 *		The parameter could be qualified with field names and/or subscripts
 */
typedef struct ParamRef
{
	NodeTag		type;
	int			number;			/* the number of the parameter */
	List	   *fields;			/* field names (list of Value strings) */
	List	   *indirection;	/* subscripts (list of A_Indices) */
} 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;

/*
 * ExprFieldSelect - select a field and/or array element from an expression
 *
 *		This is used in the raw parsetree to represent selection from an
 *		arbitrary expression (not a column or param reference).  Either
 *		fields or indirection may be NIL if not used.
 */
typedef struct ExprFieldSelect
{
	NodeTag		type;
	Node	   *arg;			/* the thing being selected from */
	List	   *fields;			/* field names (list of Value strings) */
	List	   *indirection;	/* subscripts (list of A_Indices) */
} ExprFieldSelect;

/*
 * ResTarget -
 *	  result target (used in target list of pre-transformed Parse trees)
 *
 * In a SELECT or INSERT target list, 'name' is either NULL or
 * the column name assigned to the value.  (If there is an 'AS ColumnLabel'
 * clause, the grammar sets 'name' from it; otherwise 'name' is initially NULL
 * and is filled in during the parse analysis phase.)
 * The 'indirection' field is not used at all.
 *
 * In an UPDATE target list, 'name' is the name of the destination column,
 * and 'indirection' stores any subscripts attached to the destination.
 * That is, our representation is UPDATE table SET name [indirection] = val.
 */
typedef struct ResTarget
{
	NodeTag		type;
	char	   *name;			/* column name or NULL */
	List	   *indirection;	/* subscripts for destination column, 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;


/****************************************************************************
 *	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.
 *
 *	  inh is TRUE for relation references that should be expanded to include
 *	  inheritance children, if the rel has any.  This *must* be FALSE for
 *	  RTEs other than RTE_RELATION entries.
 *
 *	  inFromCl marks those range variables that are listed in the FROM clause.
 *	  In SQL, the query can only refer to range variables listed in the
 *	  FROM clause, but POSTQUEL allows you to refer to tables not listed,
 *	  in which case a range table entry will be generated.	We still support
 *	  this POSTQUEL feature, although there is some doubt whether it's
 *	  convenient or merely confusing.  The flag is needed since an
 *	  implicitly-added RTE shouldn't change the namespace for unqualified
 *	  column names processed later, and it also shouldn't affect the
 *	  expansion of '*'.
 *