postgresql/src/include/parser/parse_node.h

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/*-------------------------------------------------------------------------
*
* parse_node.h
* Internal definitions for parser
*
*
* Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
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* src/include/parser/parse_node.h
*
*-------------------------------------------------------------------------
*/
#ifndef PARSE_NODE_H
#define PARSE_NODE_H
#include "nodes/parsenodes.h"
#include "utils/relcache.h"
/*
* Expression kinds distinguished by transformExpr(). Many of these are not
* semantically distinct so far as expression transformation goes; rather,
* we distinguish them so that context-specific error messages can be printed.
*
* Note: EXPR_KIND_OTHER is not used in the core code, but is left for use
* by extension code that might need to call transformExpr(). The core code
* will not enforce any context-driven restrictions on EXPR_KIND_OTHER
* expressions, so the caller would have to check for sub-selects, aggregates,
* and window functions if those need to be disallowed.
*/
typedef enum ParseExprKind
{
EXPR_KIND_NONE = 0, /* "not in an expression" */
EXPR_KIND_OTHER, /* reserved for extensions */
EXPR_KIND_JOIN_ON, /* JOIN ON */
EXPR_KIND_JOIN_USING, /* JOIN USING */
EXPR_KIND_FROM_SUBSELECT, /* sub-SELECT in FROM clause */
EXPR_KIND_FROM_FUNCTION, /* function in FROM clause */
EXPR_KIND_WHERE, /* WHERE */
EXPR_KIND_HAVING, /* HAVING */
EXPR_KIND_FILTER, /* FILTER */
EXPR_KIND_WINDOW_PARTITION, /* window definition PARTITION BY */
EXPR_KIND_WINDOW_ORDER, /* window definition ORDER BY */
EXPR_KIND_WINDOW_FRAME_RANGE, /* window frame clause with RANGE */
EXPR_KIND_WINDOW_FRAME_ROWS, /* window frame clause with ROWS */
EXPR_KIND_SELECT_TARGET, /* SELECT target list item */
EXPR_KIND_INSERT_TARGET, /* INSERT target list item */
EXPR_KIND_UPDATE_SOURCE, /* UPDATE assignment source item */
EXPR_KIND_UPDATE_TARGET, /* UPDATE assignment target item */
EXPR_KIND_GROUP_BY, /* GROUP BY */
EXPR_KIND_ORDER_BY, /* ORDER BY */
EXPR_KIND_DISTINCT_ON, /* DISTINCT ON */
EXPR_KIND_LIMIT, /* LIMIT */
EXPR_KIND_OFFSET, /* OFFSET */
EXPR_KIND_RETURNING, /* RETURNING */
EXPR_KIND_VALUES, /* VALUES */
EXPR_KIND_CHECK_CONSTRAINT, /* CHECK constraint for a table */
EXPR_KIND_DOMAIN_CHECK, /* CHECK constraint for a domain */
EXPR_KIND_COLUMN_DEFAULT, /* default value for a table column */
EXPR_KIND_FUNCTION_DEFAULT, /* default parameter value for function */
EXPR_KIND_INDEX_EXPRESSION, /* index expression */
EXPR_KIND_INDEX_PREDICATE, /* index predicate */
EXPR_KIND_ALTER_COL_TRANSFORM, /* transform expr in ALTER COLUMN TYPE */
EXPR_KIND_EXECUTE_PARAMETER, /* parameter value in EXECUTE */
EXPR_KIND_TRIGGER_WHEN /* WHEN condition in CREATE TRIGGER */
} ParseExprKind;
/*
* Function signatures for parser hooks
*/
typedef struct ParseState ParseState;
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typedef Node *(*PreParseColumnRefHook) (ParseState *pstate, ColumnRef *cref);
typedef Node *(*PostParseColumnRefHook) (ParseState *pstate, ColumnRef *cref, Node *var);
typedef Node *(*ParseParamRefHook) (ParseState *pstate, ParamRef *pref);
typedef Node *(*CoerceParamHook) (ParseState *pstate, Param *param,
Oid targetTypeId, int32 targetTypeMod,
int location);
/*
* State information used during parse analysis
*
* parentParseState: NULL in a top-level ParseState. When parsing a subquery,
* links to current parse state of outer query.
*
* p_sourcetext: source string that generated the raw parsetree being
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* analyzed, or NULL if not available. (The string is used only to
* generate cursor positions in error messages: we need it to convert
* byte-wise locations in parse structures to character-wise cursor
* positions.)
*
* p_rtable: list of RTEs that will become the rangetable of the query.
* Note that neither relname nor refname of these entries are necessarily
* unique; searching the rtable by name is a bad idea.
*
* p_joinexprs: list of JoinExpr nodes associated with p_rtable entries.
* This is one-for-one with p_rtable, but contains NULLs for non-join
* RTEs, and may be shorter than p_rtable if the last RTE(s) aren't joins.
*
* p_joinlist: list of join items (RangeTblRef and JoinExpr nodes) that
* will become the fromlist of the query's top-level FromExpr node.
*
* p_namespace: list of ParseNamespaceItems that represents the current
* namespace for table and column lookup. (The RTEs listed here may be just
* a subset of the whole rtable. See ParseNamespaceItem comments below.)
*
* p_lateral_active: TRUE if we are currently parsing a LATERAL subexpression
* of this parse level. This makes p_lateral_only namespace items visible,
* whereas they are not visible when p_lateral_active is FALSE.
*
* p_ctenamespace: list of CommonTableExprs (WITH items) that are visible
* at the moment. This is entirely different from p_namespace because a CTE
* is not an RTE, rather "visibility" means you could make an RTE from it.
*
* p_future_ctes: list of CommonTableExprs (WITH items) that are not yet
* visible due to scope rules. This is used to help improve error messages.
*
* p_parent_cte: CommonTableExpr that immediately contains the current query,
* if any.
*
* p_windowdefs: list of WindowDefs representing WINDOW and OVER clauses.
* We collect these while transforming expressions and then transform them
* afterwards (so that any resjunk tlist items needed for the sort/group
* clauses end up at the end of the query tlist). A WindowDef's location in
* this list, counting from 1, is the winref number to use to reference it.
*/
struct ParseState
{
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struct ParseState *parentParseState; /* stack link */
const char *p_sourcetext; /* source text, or NULL if not available */
List *p_rtable; /* range table so far */
List *p_joinexprs; /* JoinExprs for RTE_JOIN p_rtable entries */
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List *p_joinlist; /* join items so far (will become FromExpr
* node's fromlist) */
List *p_namespace; /* currently-referenceable RTEs (List of
* ParseNamespaceItem) */
bool p_lateral_active; /* p_lateral_only items visible? */
List *p_ctenamespace; /* current namespace for common table exprs */
List *p_future_ctes; /* common table exprs not yet in namespace */
CommonTableExpr *p_parent_cte; /* this query's containing CTE */
List *p_windowdefs; /* raw representations of window clauses */
ParseExprKind p_expr_kind; /* what kind of expression we're parsing */
int p_next_resno; /* next targetlist resno to assign */
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List *p_locking_clause; /* raw FOR UPDATE/FOR SHARE info */
Node *p_value_substitute; /* what to replace VALUE with, if any */
bool p_hasAggs;
bool p_hasWindowFuncs;
bool p_hasSubLinks;
bool p_hasModifyingCTE;
bool p_is_insert;
bool p_is_update;
bool p_locked_from_parent;
Relation p_target_relation;
RangeTblEntry *p_target_rangetblentry;
/*
* Optional hook functions for parser callbacks. These are null unless
* set up by the caller of make_parsestate.
*/
PreParseColumnRefHook p_pre_columnref_hook;
PostParseColumnRefHook p_post_columnref_hook;
ParseParamRefHook p_paramref_hook;
CoerceParamHook p_coerce_param_hook;
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void *p_ref_hook_state; /* common passthrough link for above */
};
/*
* An element of a namespace list.
*
* Namespace items with p_rel_visible set define which RTEs are accessible by
* qualified names, while those with p_cols_visible set define which RTEs are
* accessible by unqualified names. These sets are different because a JOIN
* without an alias does not hide the contained tables (so they must be
* visible for qualified references) but it does hide their columns
* (unqualified references to the columns refer to the JOIN, not the member
* tables, so we must not complain that such a reference is ambiguous).
* Various special RTEs such as NEW/OLD for rules may also appear with only
* one flag set.
*
* While processing the FROM clause, namespace items may appear with
* p_lateral_only set, meaning they are visible only to LATERAL
* subexpressions. (The pstate's p_lateral_active flag tells whether we are
* inside such a subexpression at the moment.) If p_lateral_ok is not set,
* it's an error to actually use such a namespace item. One might think it
* would be better to just exclude such items from visibility, but the wording
* of SQL:2008 requires us to do it this way.
*
* At no time should a namespace list contain two entries that conflict
* according to the rules in checkNameSpaceConflicts; but note that those
* are more complicated than "must have different alias names", so in practice
* code searching a namespace list has to check for ambiguous references.
*/
typedef struct ParseNamespaceItem
{
RangeTblEntry *p_rte; /* The relation's rangetable entry */
bool p_rel_visible; /* Relation name is visible? */
bool p_cols_visible; /* Column names visible as unqualified refs? */
bool p_lateral_only; /* Is only visible to LATERAL expressions? */
bool p_lateral_ok; /* If so, does join type allow use? */
} ParseNamespaceItem;
/* Support for parser_errposition_callback function */
typedef struct ParseCallbackState
{
ParseState *pstate;
int location;
ErrorContextCallback errcallback;
} ParseCallbackState;
extern ParseState *make_parsestate(ParseState *parentParseState);
extern void free_parsestate(ParseState *pstate);
extern int parser_errposition(ParseState *pstate, int location);
extern void setup_parser_errposition_callback(ParseCallbackState *pcbstate,
ParseState *pstate, int location);
extern void cancel_parser_errposition_callback(ParseCallbackState *pcbstate);
extern Var *make_var(ParseState *pstate, RangeTblEntry *rte, int attrno,
int location);
Improve handling of domains over arrays. This patch eliminates various bizarre behaviors caused by sloppy thinking about the difference between a domain type and its underlying array type. In particular, the operation of updating one element of such an array has to be considered as yielding a value of the underlying array type, *not* a value of the domain, because there's no assurance that the domain's CHECK constraints are still satisfied. If we're intending to store the result back into a domain column, we have to re-cast to the domain type so that constraints are re-checked. For similar reasons, such a domain can't be blindly matched to an ANYARRAY polymorphic parameter, because the polymorphic function is likely to apply array-ish operations that could invalidate the domain constraints. For the moment, we just forbid such matching. We might later wish to insert an automatic downcast to the underlying array type, but such a change should also change matching of domains to ANYELEMENT for consistency. To ensure that all such logic is rechecked, this patch removes the original hack of setting a domain's pg_type.typelem field to match its base type; the typelem will always be zero instead. In those places where it's really okay to look through the domain type with no other logic changes, use the newly added get_base_element_type function in place of get_element_type. catversion bumped due to change in pg_type contents. Per bug #5717 from Richard Huxton and subsequent discussion.
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extern Oid transformArrayType(Oid *arrayType, int32 *arrayTypmod);
extern ArrayRef *transformArraySubscripts(ParseState *pstate,
Node *arrayBase,
Oid arrayType,
Oid elementType,
Improve handling of domains over arrays. This patch eliminates various bizarre behaviors caused by sloppy thinking about the difference between a domain type and its underlying array type. In particular, the operation of updating one element of such an array has to be considered as yielding a value of the underlying array type, *not* a value of the domain, because there's no assurance that the domain's CHECK constraints are still satisfied. If we're intending to store the result back into a domain column, we have to re-cast to the domain type so that constraints are re-checked. For similar reasons, such a domain can't be blindly matched to an ANYARRAY polymorphic parameter, because the polymorphic function is likely to apply array-ish operations that could invalidate the domain constraints. For the moment, we just forbid such matching. We might later wish to insert an automatic downcast to the underlying array type, but such a change should also change matching of domains to ANYELEMENT for consistency. To ensure that all such logic is rechecked, this patch removes the original hack of setting a domain's pg_type.typelem field to match its base type; the typelem will always be zero instead. In those places where it's really okay to look through the domain type with no other logic changes, use the newly added get_base_element_type function in place of get_element_type. catversion bumped due to change in pg_type contents. Per bug #5717 from Richard Huxton and subsequent discussion.
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int32 arrayTypMod,
List *indirection,
Node *assignFrom);
extern Const *make_const(ParseState *pstate, Value *value, int location);
#endif /* PARSE_NODE_H */