PostgreSQL Source Code  git master
parse_node.h
Go to the documentation of this file.
1 /*-------------------------------------------------------------------------
2  *
3  * parse_node.h
4  * Internal definitions for parser
5  *
6  *
7  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * src/include/parser/parse_node.h
11  *
12  *-------------------------------------------------------------------------
13  */
14 #ifndef PARSE_NODE_H
15 #define PARSE_NODE_H
16 
17 #include "nodes/parsenodes.h"
18 #include "utils/queryenvironment.h"
19 #include "utils/relcache.h"
20 
21 
22 /* Forward references for some structs declared below */
23 typedef struct ParseState ParseState;
26 
27 /*
28  * Expression kinds distinguished by transformExpr(). Many of these are not
29  * semantically distinct so far as expression transformation goes; rather,
30  * we distinguish them so that context-specific error messages can be printed.
31  *
32  * Note: EXPR_KIND_OTHER is not used in the core code, but is left for use
33  * by extension code that might need to call transformExpr(). The core code
34  * will not enforce any context-driven restrictions on EXPR_KIND_OTHER
35  * expressions, so the caller would have to check for sub-selects, aggregates,
36  * window functions, SRFs, etc if those need to be disallowed.
37  */
38 typedef enum ParseExprKind
39 {
40  EXPR_KIND_NONE = 0, /* "not in an expression" */
41  EXPR_KIND_OTHER, /* reserved for extensions */
42  EXPR_KIND_JOIN_ON, /* JOIN ON */
43  EXPR_KIND_JOIN_USING, /* JOIN USING */
44  EXPR_KIND_FROM_SUBSELECT, /* sub-SELECT in FROM clause */
45  EXPR_KIND_FROM_FUNCTION, /* function in FROM clause */
46  EXPR_KIND_WHERE, /* WHERE */
47  EXPR_KIND_HAVING, /* HAVING */
48  EXPR_KIND_FILTER, /* FILTER */
49  EXPR_KIND_WINDOW_PARTITION, /* window definition PARTITION BY */
50  EXPR_KIND_WINDOW_ORDER, /* window definition ORDER BY */
51  EXPR_KIND_WINDOW_FRAME_RANGE, /* window frame clause with RANGE */
52  EXPR_KIND_WINDOW_FRAME_ROWS, /* window frame clause with ROWS */
53  EXPR_KIND_WINDOW_FRAME_GROUPS, /* window frame clause with GROUPS */
54  EXPR_KIND_SELECT_TARGET, /* SELECT target list item */
55  EXPR_KIND_INSERT_TARGET, /* INSERT target list item */
56  EXPR_KIND_UPDATE_SOURCE, /* UPDATE assignment source item */
57  EXPR_KIND_UPDATE_TARGET, /* UPDATE assignment target item */
58  EXPR_KIND_GROUP_BY, /* GROUP BY */
59  EXPR_KIND_ORDER_BY, /* ORDER BY */
60  EXPR_KIND_DISTINCT_ON, /* DISTINCT ON */
61  EXPR_KIND_LIMIT, /* LIMIT */
62  EXPR_KIND_OFFSET, /* OFFSET */
63  EXPR_KIND_RETURNING, /* RETURNING */
64  EXPR_KIND_VALUES, /* VALUES */
65  EXPR_KIND_VALUES_SINGLE, /* single-row VALUES (in INSERT only) */
66  EXPR_KIND_CHECK_CONSTRAINT, /* CHECK constraint for a table */
67  EXPR_KIND_DOMAIN_CHECK, /* CHECK constraint for a domain */
68  EXPR_KIND_COLUMN_DEFAULT, /* default value for a table column */
69  EXPR_KIND_FUNCTION_DEFAULT, /* default parameter value for function */
70  EXPR_KIND_INDEX_EXPRESSION, /* index expression */
71  EXPR_KIND_INDEX_PREDICATE, /* index predicate */
72  EXPR_KIND_STATS_EXPRESSION, /* extended statistics expression */
73  EXPR_KIND_ALTER_COL_TRANSFORM, /* transform expr in ALTER COLUMN TYPE */
74  EXPR_KIND_EXECUTE_PARAMETER, /* parameter value in EXECUTE */
75  EXPR_KIND_TRIGGER_WHEN, /* WHEN condition in CREATE TRIGGER */
76  EXPR_KIND_POLICY, /* USING or WITH CHECK expr in policy */
77  EXPR_KIND_PARTITION_BOUND, /* partition bound expression */
78  EXPR_KIND_PARTITION_EXPRESSION, /* PARTITION BY expression */
79  EXPR_KIND_CALL_ARGUMENT, /* procedure argument in CALL */
80  EXPR_KIND_COPY_WHERE, /* WHERE condition in COPY FROM */
81  EXPR_KIND_GENERATED_COLUMN, /* generation expression for a column */
82  EXPR_KIND_CYCLE_MARK, /* cycle mark value */
84 
85 
86 /*
87  * Function signatures for parser hooks
88  */
89 typedef Node *(*PreParseColumnRefHook) (ParseState *pstate, ColumnRef *cref);
90 typedef Node *(*PostParseColumnRefHook) (ParseState *pstate, ColumnRef *cref, Node *var);
91 typedef Node *(*ParseParamRefHook) (ParseState *pstate, ParamRef *pref);
92 typedef Node *(*CoerceParamHook) (ParseState *pstate, Param *param,
93  Oid targetTypeId, int32 targetTypeMod,
94  int location);
95 
96 
97 /*
98  * State information used during parse analysis
99  *
100  * parentParseState: NULL in a top-level ParseState. When parsing a subquery,
101  * links to current parse state of outer query.
102  *
103  * p_sourcetext: source string that generated the raw parsetree being
104  * analyzed, or NULL if not available. (The string is used only to
105  * generate cursor positions in error messages: we need it to convert
106  * byte-wise locations in parse structures to character-wise cursor
107  * positions.)
108  *
109  * p_rtable: list of RTEs that will become the rangetable of the query.
110  * Note that neither relname nor refname of these entries are necessarily
111  * unique; searching the rtable by name is a bad idea.
112  *
113  * p_joinexprs: list of JoinExpr nodes associated with p_rtable entries.
114  * This is one-for-one with p_rtable, but contains NULLs for non-join
115  * RTEs, and may be shorter than p_rtable if the last RTE(s) aren't joins.
116  *
117  * p_joinlist: list of join items (RangeTblRef and JoinExpr nodes) that
118  * will become the fromlist of the query's top-level FromExpr node.
119  *
120  * p_namespace: list of ParseNamespaceItems that represents the current
121  * namespace for table and column lookup. (The RTEs listed here may be just
122  * a subset of the whole rtable. See ParseNamespaceItem comments below.)
123  *
124  * p_lateral_active: true if we are currently parsing a LATERAL subexpression
125  * of this parse level. This makes p_lateral_only namespace items visible,
126  * whereas they are not visible when p_lateral_active is FALSE.
127  *
128  * p_ctenamespace: list of CommonTableExprs (WITH items) that are visible
129  * at the moment. This is entirely different from p_namespace because a CTE
130  * is not an RTE, rather "visibility" means you could make an RTE from it.
131  *
132  * p_future_ctes: list of CommonTableExprs (WITH items) that are not yet
133  * visible due to scope rules. This is used to help improve error messages.
134  *
135  * p_parent_cte: CommonTableExpr that immediately contains the current query,
136  * if any.
137  *
138  * p_target_relation: target relation, if query is INSERT, UPDATE, or DELETE.
139  *
140  * p_target_nsitem: target relation's ParseNamespaceItem.
141  *
142  * p_is_insert: true to process assignment expressions like INSERT, false
143  * to process them like UPDATE. (Note this can change intra-statement, for
144  * cases like INSERT ON CONFLICT UPDATE.)
145  *
146  * p_windowdefs: list of WindowDefs representing WINDOW and OVER clauses.
147  * We collect these while transforming expressions and then transform them
148  * afterwards (so that any resjunk tlist items needed for the sort/group
149  * clauses end up at the end of the query tlist). A WindowDef's location in
150  * this list, counting from 1, is the winref number to use to reference it.
151  *
152  * p_expr_kind: kind of expression we're currently parsing, as per enum above;
153  * EXPR_KIND_NONE when not in an expression.
154  *
155  * p_next_resno: next TargetEntry.resno to assign, starting from 1.
156  *
157  * p_multiassign_exprs: partially-processed MultiAssignRef source expressions.
158  *
159  * p_locking_clause: query's FOR UPDATE/FOR SHARE clause, if any.
160  *
161  * p_locked_from_parent: true if parent query level applies FOR UPDATE/SHARE
162  * to this subquery as a whole.
163  *
164  * p_resolve_unknowns: resolve unknown-type SELECT output columns as type TEXT
165  * (this is true by default).
166  *
167  * p_hasAggs, p_hasWindowFuncs, etc: true if we've found any of the indicated
168  * constructs in the query.
169  *
170  * p_last_srf: the set-returning FuncExpr or OpExpr most recently found in
171  * the query, or NULL if none.
172  *
173  * p_pre_columnref_hook, etc: optional parser hook functions for modifying the
174  * interpretation of ColumnRefs and ParamRefs.
175  *
176  * p_ref_hook_state: passthrough state for the parser hook functions.
177  */
179 {
180  ParseState *parentParseState; /* stack link */
181  const char *p_sourcetext; /* source text, or NULL if not available */
182  List *p_rtable; /* range table so far */
183  List *p_joinexprs; /* JoinExprs for RTE_JOIN p_rtable entries */
184  List *p_joinlist; /* join items so far (will become FromExpr
185  * node's fromlist) */
186  List *p_namespace; /* currently-referenceable RTEs (List of
187  * ParseNamespaceItem) */
188  bool p_lateral_active; /* p_lateral_only items visible? */
189  List *p_ctenamespace; /* current namespace for common table exprs */
190  List *p_future_ctes; /* common table exprs not yet in namespace */
191  CommonTableExpr *p_parent_cte; /* this query's containing CTE */
192  Relation p_target_relation; /* INSERT/UPDATE/DELETE target rel */
193  ParseNamespaceItem *p_target_nsitem; /* target rel's NSItem, or NULL */
194  bool p_is_insert; /* process assignment like INSERT not UPDATE */
195  List *p_windowdefs; /* raw representations of window clauses */
196  ParseExprKind p_expr_kind; /* what kind of expression we're parsing */
197  int p_next_resno; /* next targetlist resno to assign */
198  List *p_multiassign_exprs; /* junk tlist entries for multiassign */
199  List *p_locking_clause; /* raw FOR UPDATE/FOR SHARE info */
200  bool p_locked_from_parent; /* parent has marked this subquery
201  * with FOR UPDATE/FOR SHARE */
202  bool p_resolve_unknowns; /* resolve unknown-type SELECT outputs as
203  * type text */
204 
205  QueryEnvironment *p_queryEnv; /* curr env, incl refs to enclosing env */
206 
207  /* Flags telling about things found in the query: */
208  bool p_hasAggs;
213 
214  Node *p_last_srf; /* most recent set-returning func/op found */
215 
216  /*
217  * Optional hook functions for parser callbacks. These are null unless
218  * set up by the caller of make_parsestate.
219  */
224  void *p_ref_hook_state; /* common passthrough link for above */
225 };
226 
227 /*
228  * An element of a namespace list.
229  *
230  * p_names contains the table name and column names exposed by this nsitem.
231  * (Typically it's equal to p_rte->eref, but for a JOIN USING alias it's
232  * equal to p_rte->join_using_alias. Since the USING columns will be the
233  * join's first N columns, the net effect is just that we expose only those
234  * join columns via this nsitem.)
235  *
236  * p_rte and p_rtindex link to the underlying rangetable entry.
237  *
238  * The p_nscolumns array contains info showing how to construct Vars
239  * referencing the names appearing in the p_names->colnames list.
240  *
241  * Namespace items with p_rel_visible set define which RTEs are accessible by
242  * qualified names, while those with p_cols_visible set define which RTEs are
243  * accessible by unqualified names. These sets are different because a JOIN
244  * without an alias does not hide the contained tables (so they must be
245  * visible for qualified references) but it does hide their columns
246  * (unqualified references to the columns refer to the JOIN, not the member
247  * tables, so we must not complain that such a reference is ambiguous).
248  * Various special RTEs such as NEW/OLD for rules may also appear with only
249  * one flag set.
250  *
251  * While processing the FROM clause, namespace items may appear with
252  * p_lateral_only set, meaning they are visible only to LATERAL
253  * subexpressions. (The pstate's p_lateral_active flag tells whether we are
254  * inside such a subexpression at the moment.) If p_lateral_ok is not set,
255  * it's an error to actually use such a namespace item. One might think it
256  * would be better to just exclude such items from visibility, but the wording
257  * of SQL:2008 requires us to do it this way. We also use p_lateral_ok to
258  * forbid LATERAL references to an UPDATE/DELETE target table.
259  *
260  * At no time should a namespace list contain two entries that conflict
261  * according to the rules in checkNameSpaceConflicts; but note that those
262  * are more complicated than "must have different alias names", so in practice
263  * code searching a namespace list has to check for ambiguous references.
264  */
266 {
267  Alias *p_names; /* Table and column names */
268  RangeTblEntry *p_rte; /* The relation's rangetable entry */
269  int p_rtindex; /* The relation's index in the rangetable */
270  /* array of same length as p_names->colnames: */
271  ParseNamespaceColumn *p_nscolumns; /* per-column data */
272  bool p_rel_visible; /* Relation name is visible? */
273  bool p_cols_visible; /* Column names visible as unqualified refs? */
274  bool p_lateral_only; /* Is only visible to LATERAL expressions? */
275  bool p_lateral_ok; /* If so, does join type allow use? */
276 };
277 
278 /*
279  * Data about one column of a ParseNamespaceItem.
280  *
281  * We track the info needed to construct a Var referencing the column
282  * (but only for user-defined columns; system column references and
283  * whole-row references are handled separately).
284  *
285  * p_varno and p_varattno identify the semantic referent, which is a
286  * base-relation column unless the reference is to a join USING column that
287  * isn't semantically equivalent to either join input column (because it is a
288  * FULL join or the input column requires a type coercion). In those cases
289  * p_varno and p_varattno refer to the JOIN RTE.
290  *
291  * p_varnosyn and p_varattnosyn are either identical to p_varno/p_varattno,
292  * or they specify the column's position in an aliased JOIN RTE that hides
293  * the semantic referent RTE's refname. (That could be either the JOIN RTE
294  * in which this ParseNamespaceColumn entry exists, or some lower join level.)
295  *
296  * If an RTE contains a dropped column, its ParseNamespaceColumn struct
297  * is all-zeroes. (Conventionally, test for p_varno == 0 to detect this.)
298  */
300 {
301  Index p_varno; /* rangetable index */
302  AttrNumber p_varattno; /* attribute number of the column */
303  Oid p_vartype; /* pg_type OID */
304  int32 p_vartypmod; /* type modifier value */
305  Oid p_varcollid; /* OID of collation, or InvalidOid */
306  Index p_varnosyn; /* rangetable index of syntactic referent */
307  AttrNumber p_varattnosyn; /* attribute number of syntactic referent */
308  bool p_dontexpand; /* not included in star expansion */
309 };
310 
311 /* Support for parser_errposition_callback function */
312 typedef struct ParseCallbackState
313 {
315  int location;
318 
319 
321 extern void free_parsestate(ParseState *pstate);
322 extern int parser_errposition(ParseState *pstate, int location);
323 
325  ParseState *pstate, int location);
327 
328 extern void transformContainerType(Oid *containerType, int32 *containerTypmod);
329 
331  Node *containerBase,
332  Oid containerType,
333  int32 containerTypMod,
334  List *indirection,
335  bool isAssignment);
336 
337 extern Const *make_const(ParseState *pstate, Value *value, int location);
338 
339 #endif /* PARSE_NODE_H */
bool p_hasSubLinks
Definition: parse_node.h:211
static struct @142 value
QueryEnvironment * p_queryEnv
Definition: parse_node.h:205
Node *(* PreParseColumnRefHook)(ParseState *pstate, ColumnRef *cref)
Definition: parse_node.h:89
Node *(* PostParseColumnRefHook)(ParseState *pstate, ColumnRef *cref, Node *var)
Definition: parse_node.h:90
ParseState * parentParseState
Definition: parse_node.h:180
CoerceParamHook p_coerce_param_hook
Definition: parse_node.h:223
bool p_hasTargetSRFs
Definition: parse_node.h:210
Definition: nodes.h:539
List * p_multiassign_exprs
Definition: parse_node.h:198
bool p_hasAggs
Definition: parse_node.h:208
ParseNamespaceItem * p_target_nsitem
Definition: parse_node.h:193
ErrorContextCallback errcallback
Definition: parse_node.h:316
unsigned int Oid
Definition: postgres_ext.h:31
CommonTableExpr * p_parent_cte
Definition: parse_node.h:191
ParseExprKind
Definition: parse_node.h:38
PostParseColumnRefHook p_post_columnref_hook
Definition: parse_node.h:221
signed int int32
Definition: c.h:429
bool p_hasWindowFuncs
Definition: parse_node.h:209
bool p_locked_from_parent
Definition: parse_node.h:200
RangeTblEntry * p_rte
Definition: parse_node.h:268
List * p_windowdefs
Definition: parse_node.h:195
bool p_resolve_unknowns
Definition: parse_node.h:202
AttrNumber p_varattno
Definition: parse_node.h:302
List * p_namespace
Definition: parse_node.h:186
ParseParamRefHook p_paramref_hook
Definition: parse_node.h:222
Node *(* CoerceParamHook)(ParseState *pstate, Param *param, Oid targetTypeId, int32 targetTypeMod, int location)
Definition: parse_node.h:92
int p_next_resno
Definition: parse_node.h:197
List * p_locking_clause
Definition: parse_node.h:199
const char * p_sourcetext
Definition: parse_node.h:181
Node *(* ParseParamRefHook)(ParseState *pstate, ParamRef *pref)
Definition: parse_node.h:91
bool p_hasModifyingCTE
Definition: parse_node.h:212
ParseState * make_parsestate(ParseState *parentParseState)
Definition: parse_node.c:44
ParseState * pstate
Definition: parse_node.h:314
void transformContainerType(Oid *containerType, int32 *containerTypmod)
Definition: parse_node.c:194
List * p_future_ctes
Definition: parse_node.h:190
Node * p_last_srf
Definition: parse_node.h:214
unsigned int Index
Definition: c.h:549
ParseExprKind p_expr_kind
Definition: parse_node.h:196
bool p_lateral_active
Definition: parse_node.h:188
int parser_errposition(ParseState *pstate, int location)
Definition: parse_node.c:111
void * p_ref_hook_state
Definition: parse_node.h:224
Definition: value.h:42
void setup_parser_errposition_callback(ParseCallbackState *pcbstate, ParseState *pstate, int location)
Definition: parse_node.c:145
ParseNamespaceColumn * p_nscolumns
Definition: parse_node.h:271
struct ParseCallbackState ParseCallbackState
Relation p_target_relation
Definition: parse_node.h:192
bool p_is_insert
Definition: parse_node.h:194
AttrNumber p_varattnosyn
Definition: parse_node.h:307
Const * make_const(ParseState *pstate, Value *value, int location)
Definition: parse_node.c:352
List * p_ctenamespace
Definition: parse_node.h:189
List * p_joinlist
Definition: parse_node.h:184
void free_parsestate(ParseState *pstate)
Definition: parse_node.c:77
SubscriptingRef * transformContainerSubscripts(ParseState *pstate, Node *containerBase, Oid containerType, int32 containerTypMod, List *indirection, bool isAssignment)
Definition: parse_node.c:248
PreParseColumnRefHook p_pre_columnref_hook
Definition: parse_node.h:220
Definition: pg_list.h:50
int16 AttrNumber
Definition: attnum.h:21
List * p_joinexprs
Definition: parse_node.h:183
void cancel_parser_errposition_callback(ParseCallbackState *pcbstate)
Definition: parse_node.c:161
List * p_rtable
Definition: parse_node.h:182