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Add support for user-defined I/O conversion casts.
[PostgreSQL.git] / src / backend / parser / parse_coerce.c
blob227247d4042818bd6364b997e7a24bb00e5e4067
1 /*-------------------------------------------------------------------------
2 *
3 * parse_coerce.c
4 * handle type coercions/conversions for parser
5 *
6 * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
8 *
9 *
10 * IDENTIFICATION
11 * $PostgreSQL$
12 *
13 *-------------------------------------------------------------------------
14 */
15 #include "postgres.h"
16
17 #include "catalog/pg_cast.h"
18 #include "catalog/pg_proc.h"
19 #include "catalog/pg_type.h"
20 #include "nodes/makefuncs.h"
21 #include "nodes/nodeFuncs.h"
22 #include "parser/parse_coerce.h"
23 #include "parser/parse_func.h"
24 #include "parser/parse_relation.h"
25 #include "parser/parse_type.h"
26 #include "utils/builtins.h"
27 #include "utils/fmgroids.h"
28 #include "utils/lsyscache.h"
29 #include "utils/syscache.h"
30 #include "utils/typcache.h"
31
32
33 static Node *coerce_type_typmod(Node *node,
34 Oid targetTypeId, int32 targetTypMod,
35 CoercionForm cformat, int location,
36 bool isExplicit, bool hideInputCoercion);
37 static void hide_coercion_node(Node *node);
38 static Node *build_coercion_expression(Node *node,
39 CoercionPathType pathtype,
40 Oid funcId,
41 Oid targetTypeId, int32 targetTypMod,
42 CoercionForm cformat, int location,
43 bool isExplicit);
44 static Node *coerce_record_to_complex(ParseState *pstate, Node *node,
45 Oid targetTypeId,
46 CoercionContext ccontext,
47 CoercionForm cformat,
48 int location);
49 static bool is_complex_array(Oid typid);
50
51
52 /*
53 * coerce_to_target_type()
54 * Convert an expression to a target type and typmod.
55 *
56 * This is the general-purpose entry point for arbitrary type coercion
57 * operations. Direct use of the component operations can_coerce_type,
58 * coerce_type, and coerce_type_typmod should be restricted to special
59 * cases (eg, when the conversion is expected to succeed).
60 *
61 * Returns the possibly-transformed expression tree, or NULL if the type
62 * conversion is not possible. (We do this, rather than ereport'ing directly,
63 * so that callers can generate custom error messages indicating context.)
64 *
65 * pstate - parse state (can be NULL, see coerce_type)
66 * expr - input expression tree (already transformed by transformExpr)
67 * exprtype - result type of expr
68 * targettype - desired result type
69 * targettypmod - desired result typmod
70 * ccontext, cformat - context indicators to control coercions
71 * location - parse location of the coercion request, or -1 if unknown/implicit
72 */
73 Node *
74 coerce_to_target_type(ParseState *pstate, Node *expr, Oid exprtype,
75 Oid targettype, int32 targettypmod,
76 CoercionContext ccontext,
77 CoercionForm cformat,
78 int location)
79 {
80 Node *result;
81
82 if (!can_coerce_type(1, &exprtype, &targettype, ccontext))
83 return NULL;
84
85 result = coerce_type(pstate, expr, exprtype,
86 targettype, targettypmod,
87 ccontext, cformat, location);
88
89 /*
90 * If the target is a fixed-length type, it may need a length coercion as
91 * well as a type coercion. If we find ourselves adding both, force the
92 * inner coercion node to implicit display form.
93 */
94 result = coerce_type_typmod(result,
95 targettype, targettypmod,
96 cformat, location,
97 (cformat != COERCE_IMPLICIT_CAST),
98 (result != expr && !IsA(result, Const)));
99
100 return result;
101 }
102
103
104 /*
105 * coerce_type()
106 * Convert an expression to a different type.
107 *
108 * The caller should already have determined that the coercion is possible;
109 * see can_coerce_type.
110 *
111 * Normally, no coercion to a typmod (length) is performed here. The caller
112 * must call coerce_type_typmod as well, if a typmod constraint is wanted.
113 * (But if the target type is a domain, it may internally contain a
114 * typmod constraint, which will be applied inside coerce_to_domain.)
115 * In some cases pg_cast specifies a type coercion function that also
116 * applies length conversion, and in those cases only, the result will
117 * already be properly coerced to the specified typmod.
118 *
119 * pstate is only used in the case that we are able to resolve the type of
120 * a previously UNKNOWN Param. It is okay to pass pstate = NULL if the
121 * caller does not want type information updated for Params.
122 */
123 Node *
124 coerce_type(ParseState *pstate, Node *node,
125 Oid inputTypeId, Oid targetTypeId, int32 targetTypeMod,
126 CoercionContext ccontext, CoercionForm cformat, int location)
127 {
128 Node *result;
129 CoercionPathType pathtype;
130 Oid funcId;
131
132 if (targetTypeId == inputTypeId ||
133 node == NULL)
134 {
135 /* no conversion needed */
136 return node;
137 }
138 if (targetTypeId == ANYOID ||
139 targetTypeId == ANYELEMENTOID ||
140 targetTypeId == ANYNONARRAYOID ||
141 (targetTypeId == ANYARRAYOID && inputTypeId != UNKNOWNOID) ||
142 (targetTypeId == ANYENUMOID && inputTypeId != UNKNOWNOID))
143 {
144 /*
145 * Assume can_coerce_type verified that implicit coercion is okay.
146 *
147 * Note: by returning the unmodified node here, we are saying that
148 * it's OK to treat an UNKNOWN constant as a valid input for a
149 * function accepting ANY, ANYELEMENT, or ANYNONARRAY. This should be
150 * all right, since an UNKNOWN value is still a perfectly valid Datum.
151 * However an UNKNOWN value is definitely *not* an array, and so we
152 * mustn't accept it for ANYARRAY. (Instead, we will call anyarray_in
153 * below, which will produce an error.) Likewise, UNKNOWN input is no
154 * good for ANYENUM.
155 *
156 * NB: we do NOT want a RelabelType here.
157 */
158 return node;
159 }
160 if (inputTypeId == UNKNOWNOID && IsA(node, Const))
161 {
162 /*
163 * Input is a string constant with previously undetermined type. Apply
164 * the target type's typinput function to it to produce a constant of
165 * the target type.
166 *
167 * NOTE: this case cannot be folded together with the other
168 * constant-input case, since the typinput function does not
169 * necessarily behave the same as a type conversion function. For
170 * example, int4's typinput function will reject "1.2", whereas
171 * float-to-int type conversion will round to integer.
172 *
173 * XXX if the typinput function is not immutable, we really ought to
174 * postpone evaluation of the function call until runtime. But there
175 * is no way to represent a typinput function call as an expression
176 * tree, because C-string values are not Datums. (XXX This *is*
177 * possible as of 7.3, do we want to do it?)
178 */
179 Const *con = (Const *) node;
180 Const *newcon = makeNode(Const);
181 Oid baseTypeId;
182 int32 baseTypeMod;
183 int32 inputTypeMod;
184 Type targetType;
185 ParseCallbackState pcbstate;
186
187 /*
188 * If the target type is a domain, we want to call its base type's
189 * input routine, not domain_in(). This is to avoid premature failure
190 * when the domain applies a typmod: existing input routines follow
191 * implicit-coercion semantics for length checks, which is not always
192 * what we want here. The needed check will be applied properly
193 * inside coerce_to_domain().
194 */
195 baseTypeMod = targetTypeMod;
196 baseTypeId = getBaseTypeAndTypmod(targetTypeId, &baseTypeMod);
197
198 /*
199 * For most types we pass typmod -1 to the input routine, because
200 * existing input routines follow implicit-coercion semantics for
201 * length checks, which is not always what we want here. Any length
202 * constraint will be applied later by our caller. An exception
203 * however is the INTERVAL type, for which we *must* pass the typmod
204 * or it won't be able to obey the bizarre SQL-spec input rules.
205 * (Ugly as sin, but so is this part of the spec...)
206 */
207 if (baseTypeId == INTERVALOID)
208 inputTypeMod = baseTypeMod;
209 else
210 inputTypeMod = -1;
211
212 targetType = typeidType(baseTypeId);
213
214 newcon->consttype = baseTypeId;
215 newcon->consttypmod = inputTypeMod;
216 newcon->constlen = typeLen(targetType);
217 newcon->constbyval = typeByVal(targetType);
218 newcon->constisnull = con->constisnull;
219 /* Use the leftmost of the constant's and coercion's locations */
220 if (location < 0)
221 newcon->location = con->location;
222 else if (con->location >= 0 && con->location < location)
223 newcon->location = con->location;
224 else
225 newcon->location = location;
226
227 /*
228 * Set up to point at the constant's text if the input routine
229 * throws an error.
230 */
231 setup_parser_errposition_callback(&pcbstate, pstate, con->location);
232
233 /*
234 * We assume here that UNKNOWN's internal representation is the same
235 * as CSTRING.
236 */
237 if (!con->constisnull)
238 newcon->constvalue = stringTypeDatum(targetType,
239 DatumGetCString(con->constvalue),
240 inputTypeMod);
241 else
242 newcon->constvalue = stringTypeDatum(targetType,
243 NULL,
244 inputTypeMod);
245
246 cancel_parser_errposition_callback(&pcbstate);
247
248 result = (Node *) newcon;
249
250 /* If target is a domain, apply constraints. */
251 if (baseTypeId != targetTypeId)
252 result = coerce_to_domain(result,
253 baseTypeId, baseTypeMod,
254 targetTypeId,
255 cformat, location, false, false);
256
257 ReleaseSysCache(targetType);
258
259 return result;
260 }
261 if (inputTypeId == UNKNOWNOID && IsA(node, Param) &&
262 ((Param *) node)->paramkind == PARAM_EXTERN &&
263 pstate != NULL && pstate->p_variableparams)
264 {
265 /*
266 * Input is a Param of previously undetermined type, and we want to
267 * update our knowledge of the Param's type. Find the topmost
268 * ParseState and update the state.
269 */
270 Param *param = (Param *) node;
271 int paramno = param->paramid;
272 ParseState *toppstate;
273
274 toppstate = pstate;
275 while (toppstate->parentParseState != NULL)
276 toppstate = toppstate->parentParseState;
277
278 if (paramno <= 0 || /* shouldn't happen, but... */
279 paramno > toppstate->p_numparams)
280 ereport(ERROR,
281 (errcode(ERRCODE_UNDEFINED_PARAMETER),
282 errmsg("there is no parameter $%d", paramno),
283 parser_errposition(pstate, param->location)));
284
285 if (toppstate->p_paramtypes[paramno - 1] == UNKNOWNOID)
286 {
287 /* We've successfully resolved the type */
288 toppstate->p_paramtypes[paramno - 1] = targetTypeId;
289 }
290 else if (toppstate->p_paramtypes[paramno - 1] == targetTypeId)
291 {
292 /* We previously resolved the type, and it matches */
293 }
294 else
295 {
296 /* Ooops */
297 ereport(ERROR,
298 (errcode(ERRCODE_AMBIGUOUS_PARAMETER),
299 errmsg("inconsistent types deduced for parameter $%d",
300 paramno),
301 errdetail("%s versus %s",
302 format_type_be(toppstate->p_paramtypes[paramno - 1]),
303 format_type_be(targetTypeId)),
304 parser_errposition(pstate, param->location)));
305 }
306
307 param->paramtype = targetTypeId;
308
309 /*
310 * Note: it is tempting here to set the Param's paramtypmod to
311 * targetTypeMod, but that is probably unwise because we have no
312 * infrastructure that enforces that the value delivered for a Param
313 * will match any particular typmod. Leaving it -1 ensures that a
314 * run-time length check/coercion will occur if needed.
315 */
316 param->paramtypmod = -1;
317
318 /* Use the leftmost of the param's and coercion's locations */
319 if (location >= 0 &&
320 (param->location < 0 || location < param->location))
321 param->location = location;
322
323 return (Node *) param;
324 }
325 pathtype = find_coercion_pathway(targetTypeId, inputTypeId, ccontext,
326 &funcId);
327 if (pathtype != COERCION_PATH_NONE)
328 {
329 if (pathtype != COERCION_PATH_RELABELTYPE)
330 {
331 /*
332 * Generate an expression tree representing run-time application
333 * of the conversion function. If we are dealing with a domain
334 * target type, the conversion function will yield the base type,
335 * and we need to extract the correct typmod to use from the
336 * domain's typtypmod.
337 */
338 Oid baseTypeId;
339 int32 baseTypeMod;
340
341 baseTypeMod = targetTypeMod;
342 baseTypeId = getBaseTypeAndTypmod(targetTypeId, &baseTypeMod);
343
344 result = build_coercion_expression(node, pathtype, funcId,
345 baseTypeId, baseTypeMod,
346 cformat, location,
347 (cformat != COERCE_IMPLICIT_CAST));
348
349 /*
350 * If domain, coerce to the domain type and relabel with domain
351 * type ID. We can skip the internal length-coercion step if the
352 * selected coercion function was a type-and-length coercion.
353 */
354 if (targetTypeId != baseTypeId)
355 result = coerce_to_domain(result, baseTypeId, baseTypeMod,
356 targetTypeId,
357 cformat, location, true,
358 exprIsLengthCoercion(result,
359 NULL));
360 }
361 else
362 {
363 /*
364 * We don't need to do a physical conversion, but we do need to
365 * attach a RelabelType node so that the expression will be seen
366 * to have the intended type when inspected by higher-level code.
367 *
368 * Also, domains may have value restrictions beyond the base type
369 * that must be accounted for. If the destination is a domain
370 * then we won't need a RelabelType node.
371 */
372 result = coerce_to_domain(node, InvalidOid, -1, targetTypeId,
373 cformat, location, false, false);
374 if (result == node)
375 {
376 /*
377 * XXX could we label result with exprTypmod(node) instead of
378 * default -1 typmod, to save a possible length-coercion
379 * later? Would work if both types have same interpretation of
380 * typmod, which is likely but not certain.
381 */
382 RelabelType *r = makeRelabelType((Expr *) result,
383 targetTypeId, -1,
384 cformat);
385
386 r->location = location;
387 result = (Node *) r;
388 }
389 }
390 return result;
391 }
392 if (inputTypeId == RECORDOID &&
393 ISCOMPLEX(targetTypeId))
394 {
395 /* Coerce a RECORD to a specific complex type */
396 return coerce_record_to_complex(pstate, node, targetTypeId,
397 ccontext, cformat, location);
398 }
399 if (targetTypeId == RECORDOID &&
400 ISCOMPLEX(inputTypeId))
401 {
402 /* Coerce a specific complex type to RECORD */
403 /* NB: we do NOT want a RelabelType here */
404 return node;
405 }
406 #ifdef NOT_USED
407 if (inputTypeId == RECORDARRAYOID &&
408 is_complex_array(targetTypeId))
409 {
410 /* Coerce record[] to a specific complex array type */
411 /* not implemented yet ... */
412 }
413 #endif
414 if (targetTypeId == RECORDARRAYOID &&
415 is_complex_array(inputTypeId))
416 {
417 /* Coerce a specific complex array type to record[] */
418 /* NB: we do NOT want a RelabelType here */
419 return node;
420 }
421 if (typeInheritsFrom(inputTypeId, targetTypeId))
422 {
423 /*
424 * Input class type is a subclass of target, so generate an
425 * appropriate runtime conversion (removing unneeded columns and
426 * possibly rearranging the ones that are wanted).
427 */
428 ConvertRowtypeExpr *r = makeNode(ConvertRowtypeExpr);
429
430 r->arg = (Expr *) node;
431 r->resulttype = targetTypeId;
432 r->convertformat = cformat;
433 r->location = location;
434 return (Node *) r;
435 }
436 /* If we get here, caller blew it */
437 elog(ERROR, "failed to find conversion function from %s to %s",
438 format_type_be(inputTypeId), format_type_be(targetTypeId));
439 return NULL; /* keep compiler quiet */
440 }
441
442
443 /*
444 * can_coerce_type()
445 * Can input_typeids be coerced to target_typeids?
446 *
447 * We must be told the context (CAST construct, assignment, implicit coercion)
448 * as this determines the set of available casts.
449 */
450 bool
451 can_coerce_type(int nargs, Oid *input_typeids, Oid *target_typeids,
452 CoercionContext ccontext)
453 {
454 bool have_generics = false;
455 int i;
456
457 /* run through argument list... */
458 for (i = 0; i < nargs; i++)
459 {
460 Oid inputTypeId = input_typeids[i];
461 Oid targetTypeId = target_typeids[i];
462 CoercionPathType pathtype;
463 Oid funcId;
464
465 /* no problem if same type */
466 if (inputTypeId == targetTypeId)
467 continue;
468
469 /* accept if target is ANY */
470 if (targetTypeId == ANYOID)
471 continue;
472
473 /* accept if target is polymorphic, for now */
474 if (IsPolymorphicType(targetTypeId))
475 {
476 have_generics = true; /* do more checking later */
477 continue;
478 }
479
480 /*
481 * If input is an untyped string constant, assume we can convert it to
482 * anything.
483 */
484 if (inputTypeId == UNKNOWNOID)
485 continue;
486
487 /*
488 * If pg_cast shows that we can coerce, accept. This test now covers
489 * both binary-compatible and coercion-function cases.
490 */
491 pathtype = find_coercion_pathway(targetTypeId, inputTypeId, ccontext,
492 &funcId);
493 if (pathtype != COERCION_PATH_NONE)
494 continue;
495
496 /*
497 * If input is RECORD and target is a composite type, assume we can
498 * coerce (may need tighter checking here)
499 */
500 if (inputTypeId == RECORDOID &&
501 ISCOMPLEX(targetTypeId))
502 continue;
503
504 /*
505 * If input is a composite type and target is RECORD, accept
506 */
507 if (targetTypeId == RECORDOID &&
508 ISCOMPLEX(inputTypeId))
509 continue;
510
511 #ifdef NOT_USED /* not implemented yet */
512 /*
513 * If input is record[] and target is a composite array type,
514 * assume we can coerce (may need tighter checking here)
515 */
516 if (inputTypeId == RECORDARRAYOID &&
517 is_complex_array(targetTypeId))
518 continue;
519 #endif
520
521 /*
522 * If input is a composite array type and target is record[], accept
523 */
524 if (targetTypeId == RECORDARRAYOID &&
525 is_complex_array(inputTypeId))
526 continue;
527
528 /*
529 * If input is a class type that inherits from target, accept
530 */
531 if (typeInheritsFrom(inputTypeId, targetTypeId))
532 continue;
533
534 /*
535 * Else, cannot coerce at this argument position
536 */
537 return false;
538 }
539
540 /* If we found any generic argument types, cross-check them */
541 if (have_generics)
542 {
543 if (!check_generic_type_consistency(input_typeids, target_typeids,
544 nargs))
545 return false;
546 }
547
548 return true;
549 }
550
551
552 /*
553 * Create an expression tree to represent coercion to a domain type.
554 *
555 * 'arg': input expression
556 * 'baseTypeId': base type of domain, if known (pass InvalidOid if caller
557 * has not bothered to look this up)
558 * 'baseTypeMod': base type typmod of domain, if known (pass -1 if caller
559 * has not bothered to look this up)
560 * 'typeId': target type to coerce to
561 * 'cformat': coercion format
562 * 'location': coercion request location
563 * 'hideInputCoercion': if true, hide the input coercion under this one.
564 * 'lengthCoercionDone': if true, caller already accounted for length,
565 * ie the input is already of baseTypMod as well as baseTypeId.
566 *
567 * If the target type isn't a domain, the given 'arg' is returned as-is.
568 */
569 Node *
570 coerce_to_domain(Node *arg, Oid baseTypeId, int32 baseTypeMod, Oid typeId,
571 CoercionForm cformat, int location,
572 bool hideInputCoercion,
573 bool lengthCoercionDone)
574 {
575 CoerceToDomain *result;
576
577 /* Get the base type if it hasn't been supplied */
578 if (baseTypeId == InvalidOid)
579 baseTypeId = getBaseTypeAndTypmod(typeId, &baseTypeMod);
580
581 /* If it isn't a domain, return the node as it was passed in */
582 if (baseTypeId == typeId)
583 return arg;
584
585 /* Suppress display of nested coercion steps */
586 if (hideInputCoercion)
587 hide_coercion_node(arg);
588
589 /*
590 * If the domain applies a typmod to its base type, build the appropriate
591 * coercion step. Mark it implicit for display purposes, because we don't
592 * want it shown separately by ruleutils.c; but the isExplicit flag passed
593 * to the conversion function depends on the manner in which the domain
594 * coercion is invoked, so that the semantics of implicit and explicit
595 * coercion differ. (Is that really the behavior we want?)
596 *
597 * NOTE: because we apply this as part of the fixed expression structure,
598 * ALTER DOMAIN cannot alter the typtypmod. But it's unclear that that
599 * would be safe to do anyway, without lots of knowledge about what the
600 * base type thinks the typmod means.
601 */
602 if (!lengthCoercionDone)
603 {
604 if (baseTypeMod >= 0)
605 arg = coerce_type_typmod(arg, baseTypeId, baseTypeMod,
606 COERCE_IMPLICIT_CAST, location,
607 (cformat != COERCE_IMPLICIT_CAST),
608 false);
609 }
610
611 /*
612 * Now build the domain coercion node. This represents run-time checking
613 * of any constraints currently attached to the domain. This also ensures
614 * that the expression is properly labeled as to result type.
615 */
616 result = makeNode(CoerceToDomain);
617 result->arg = (Expr *) arg;
618 result->resulttype = typeId;
619 result->resulttypmod = -1; /* currently, always -1 for domains */
620 result->coercionformat = cformat;
621 result->location = location;
622
623 return (Node *) result;
624 }
625
626
627 /*
628 * coerce_type_typmod()
629 * Force a value to a particular typmod, if meaningful and possible.
630 *
631 * This is applied to values that are going to be stored in a relation
632 * (where we have an atttypmod for the column) as well as values being
633 * explicitly CASTed (where the typmod comes from the target type spec).
634 *
635 * The caller must have already ensured that the value is of the correct
636 * type, typically by applying coerce_type.
637 *
638 * cformat determines the display properties of the generated node (if any),
639 * while isExplicit may affect semantics. If hideInputCoercion is true
640 * *and* we generate a node, the input node is forced to IMPLICIT display
641 * form, so that only the typmod coercion node will be visible when
642 * displaying the expression.
643 *
644 * NOTE: this does not need to work on domain types, because any typmod
645 * coercion for a domain is considered to be part of the type coercion
646 * needed to produce the domain value in the first place. So, no getBaseType.
647 */
648 static Node *
649 coerce_type_typmod(Node *node, Oid targetTypeId, int32 targetTypMod,
650 CoercionForm cformat, int location,
651 bool isExplicit, bool hideInputCoercion)
652 {
653 CoercionPathType pathtype;
654 Oid funcId;
655
656 /*
657 * A negative typmod is assumed to mean that no coercion is wanted. Also,
658 * skip coercion if already done.
659 */
660 if (targetTypMod < 0 || targetTypMod == exprTypmod(node))
661 return node;
662
663 pathtype = find_typmod_coercion_function(targetTypeId, &funcId);
664
665 if (pathtype != COERCION_PATH_NONE)
666 {
667 /* Suppress display of nested coercion steps */
668 if (hideInputCoercion)
669 hide_coercion_node(node);
670
671 node = build_coercion_expression(node, pathtype, funcId,
672 targetTypeId, targetTypMod,
673 cformat, location,
674 isExplicit);
675 }
676
677 return node;
678 }
679
680 /*
681 * Mark a coercion node as IMPLICIT so it will never be displayed by
682 * ruleutils.c. We use this when we generate a nest of coercion nodes
683 * to implement what is logically one conversion; the inner nodes are
684 * forced to IMPLICIT_CAST format. This does not change their semantics,
685 * only display behavior.
686 *
687 * It is caller error to call this on something that doesn't have a
688 * CoercionForm field.
689 */
690 static void
691 hide_coercion_node(Node *node)
692 {
693 if (IsA(node, FuncExpr))
694 ((FuncExpr *) node)->funcformat = COERCE_IMPLICIT_CAST;
695 else if (IsA(node, RelabelType))
696 ((RelabelType *) node)->relabelformat = COERCE_IMPLICIT_CAST;
697 else if (IsA(node, CoerceViaIO))
698 ((CoerceViaIO *) node)->coerceformat = COERCE_IMPLICIT_CAST;
699 else if (IsA(node, ArrayCoerceExpr))
700 ((ArrayCoerceExpr *) node)->coerceformat = COERCE_IMPLICIT_CAST;
701 else if (IsA(node, ConvertRowtypeExpr))
702 ((ConvertRowtypeExpr *) node)->convertformat = COERCE_IMPLICIT_CAST;
703 else if (IsA(node, RowExpr))
704 ((RowExpr *) node)->row_format = COERCE_IMPLICIT_CAST;
705 else if (IsA(node, CoerceToDomain))
706 ((CoerceToDomain *) node)->coercionformat = COERCE_IMPLICIT_CAST;
707 else
708 elog(ERROR, "unsupported node type: %d", (int) nodeTag(node));
709 }
710
711 /*
712 * build_coercion_expression()
713 * Construct an expression tree for applying a pg_cast entry.
714 *
715 * This is used for both type-coercion and length-coercion operations,
716 * since there is no difference in terms of the calling convention.
717 */
718 static Node *
719 build_coercion_expression(Node *node,
720 CoercionPathType pathtype,
721 Oid funcId,
722 Oid targetTypeId, int32 targetTypMod,
723 CoercionForm cformat, int location,
724 bool isExplicit)
725 {
726 int nargs = 0;
727
728 if (OidIsValid(funcId))
729 {
730 HeapTuple tp;
731 Form_pg_proc procstruct;
732
733 tp = SearchSysCache(PROCOID,
734 ObjectIdGetDatum(funcId),
735 0, 0, 0);
736 if (!HeapTupleIsValid(tp))
737 elog(ERROR, "cache lookup failed for function %u", funcId);
738 procstruct = (Form_pg_proc) GETSTRUCT(tp);
739
740 /*
741 * These Asserts essentially check that function is a legal coercion
742 * function. We can't make the seemingly obvious tests on prorettype
743 * and proargtypes[0], even in the COERCION_PATH_FUNC case, because of
744 * various binary-compatibility cases.
745 */
746 /* Assert(targetTypeId == procstruct->prorettype); */
747 Assert(!procstruct->proretset);
748 Assert(!procstruct->proisagg);
749 nargs = procstruct->pronargs;
750 Assert(nargs >= 1 && nargs <= 3);
751 /* Assert(procstruct->proargtypes.values[0] == exprType(node)); */
752 Assert(nargs < 2 || procstruct->proargtypes.values[1] == INT4OID);
753 Assert(nargs < 3 || procstruct->proargtypes.values[2] == BOOLOID);
754
755 ReleaseSysCache(tp);
756 }
757
758 if (pathtype == COERCION_PATH_FUNC)
759 {
760 /* We build an ordinary FuncExpr with special arguments */
761 FuncExpr *fexpr;
762 List *args;
763 Const *cons;
764
765 Assert(OidIsValid(funcId));
766
767 args = list_make1(node);
768
769 if (nargs >= 2)
770 {
771 /* Pass target typmod as an int4 constant */
772 cons = makeConst(INT4OID,
773 -1,
774 sizeof(int32),
775 Int32GetDatum(targetTypMod),
776 false,
777 true);
778
779 args = lappend(args, cons);
780 }
781
782 if (nargs == 3)
783 {
784 /* Pass it a boolean isExplicit parameter, too */
785 cons = makeConst(BOOLOID,
786 -1,
787 sizeof(bool),
788 BoolGetDatum(isExplicit),
789 false,
790 true);
791
792 args = lappend(args, cons);
793 }
794
795 fexpr = makeFuncExpr(funcId, targetTypeId, args, cformat);
796 fexpr->location = location;
797 return (Node *) fexpr;
798 }
799 else if (pathtype == COERCION_PATH_ARRAYCOERCE)
800 {
801 /* We need to build an ArrayCoerceExpr */
802 ArrayCoerceExpr *acoerce = makeNode(ArrayCoerceExpr);
803
804 acoerce->arg = (Expr *) node;
805 acoerce->elemfuncid = funcId;
806 acoerce->resulttype = targetTypeId;
807
808 /*
809 * Label the output as having a particular typmod only if we are
810 * really invoking a length-coercion function, ie one with more than
811 * one argument.
812 */
813 acoerce->resulttypmod = (nargs >= 2) ? targetTypMod : -1;
814 acoerce->isExplicit = isExplicit;
815 acoerce->coerceformat = cformat;
816 acoerce->location = location;
817
818 return (Node *) acoerce;
819 }
820 else if (pathtype == COERCION_PATH_COERCEVIAIO)
821 {
822 /* We need to build a CoerceViaIO node */
823 CoerceViaIO *iocoerce = makeNode(CoerceViaIO);
824
825 Assert(!OidIsValid(funcId));
826
827 iocoerce->arg = (Expr *) node;
828 iocoerce->resulttype = targetTypeId;
829 iocoerce->coerceformat = cformat;
830 iocoerce->location = location;
831
832 return (Node *) iocoerce;
833 }
834 else
835 {
836 elog(ERROR, "unsupported pathtype %d in build_coercion_expression",
837 (int) pathtype);
838 return NULL; /* keep compiler quiet */
839 }
840 }
841
842
843 /*
844 * coerce_record_to_complex
845 * Coerce a RECORD to a specific composite type.
846 *
847 * Currently we only support this for inputs that are RowExprs or whole-row
848 * Vars.
849 */
850 static Node *
851 coerce_record_to_complex(ParseState *pstate, Node *node,
852 Oid targetTypeId,
853 CoercionContext ccontext,
854 CoercionForm cformat,
855 int location)
856 {
857 RowExpr *rowexpr;
858 TupleDesc tupdesc;
859 List *args = NIL;
860 List *newargs;
861 int i;
862 int ucolno;
863 ListCell *arg;
864
865 if (node && IsA(node, RowExpr))
866 {
867 /*
868 * Since the RowExpr must be of type RECORD, we needn't worry about it
869 * containing any dropped columns.
870 */
871 args = ((RowExpr *) node)->args;
872 }
873 else if (node && IsA(node, Var) &&
874 ((Var *) node)->varattno == InvalidAttrNumber)
875 {
876 int rtindex = ((Var *) node)->varno;
877 int sublevels_up = ((Var *) node)->varlevelsup;
878 int vlocation = ((Var *) node)->location;
879 RangeTblEntry *rte;
880
881 rte = GetRTEByRangeTablePosn(pstate, rtindex, sublevels_up);
882 expandRTE(rte, rtindex, sublevels_up, vlocation, false,
883 NULL, &args);
884 }
885 else
886 ereport(ERROR,
887 (errcode(ERRCODE_CANNOT_COERCE),
888 errmsg("cannot cast type %s to %s",
889 format_type_be(RECORDOID),
890 format_type_be(targetTypeId)),
891 parser_coercion_errposition(pstate, location, node)));
892
893 tupdesc = lookup_rowtype_tupdesc(targetTypeId, -1);
894 newargs = NIL;
895 ucolno = 1;
896 arg = list_head(args);
897 for (i = 0; i < tupdesc->natts; i++)
898 {
899 Node *expr;
900 Node *cexpr;
901 Oid exprtype;
902
903 /* Fill in NULLs for dropped columns in rowtype */
904 if (tupdesc->attrs[i]->attisdropped)
905 {
906 /*
907 * can't use atttypid here, but it doesn't really matter what type
908 * the Const claims to be.
909 */
910 newargs = lappend(newargs, makeNullConst(INT4OID, -1));
911 continue;
912 }
913
914 if (arg == NULL)
915 ereport(ERROR,
916 (errcode(ERRCODE_CANNOT_COERCE),
917 errmsg("cannot cast type %s to %s",
918 format_type_be(RECORDOID),
919 format_type_be(targetTypeId)),
920 errdetail("Input has too few columns."),
921 parser_coercion_errposition(pstate, location, node)));
922 expr = (Node *) lfirst(arg);
923 exprtype = exprType(expr);
924
925 cexpr = coerce_to_target_type(pstate,
926 expr, exprtype,
927 tupdesc->attrs[i]->atttypid,
928 tupdesc->attrs[i]->atttypmod,
929 ccontext,
930 COERCE_IMPLICIT_CAST,
931 -1);
932 if (cexpr == NULL)
933 ereport(ERROR,
934 (errcode(ERRCODE_CANNOT_COERCE),
935 errmsg("cannot cast type %s to %s",
936 format_type_be(RECORDOID),
937 format_type_be(targetTypeId)),
938 errdetail("Cannot cast type %s to %s in column %d.",
939 format_type_be(exprtype),
940 format_type_be(tupdesc->attrs[i]->atttypid),
941 ucolno),
942 parser_coercion_errposition(pstate, location, expr)));
943 newargs = lappend(newargs, cexpr);
944 ucolno++;
945 arg = lnext(arg);
946 }
947 if (arg != NULL)
948 ereport(ERROR,
949 (errcode(ERRCODE_CANNOT_COERCE),
950 errmsg("cannot cast type %s to %s",
951 format_type_be(RECORDOID),
952 format_type_be(targetTypeId)),
953 errdetail("Input has too many columns."),
954 parser_coercion_errposition(pstate, location, node)));
955
956 ReleaseTupleDesc(tupdesc);
957
958 rowexpr = makeNode(RowExpr);
959 rowexpr->args = newargs;
960 rowexpr->row_typeid = targetTypeId;
961 rowexpr->row_format = cformat;
962 rowexpr->colnames = NIL; /* not needed for named target type */
963 rowexpr->location = location;
964 return (Node *) rowexpr;
965 }
966
967 /*
968 * coerce_to_boolean()
969 * Coerce an argument of a construct that requires boolean input
970 * (AND, OR, NOT, etc). Also check that input is not a set.
971 *
972 * Returns the possibly-transformed node tree.
973 *
974 * As with coerce_type, pstate may be NULL if no special unknown-Param
975 * processing is wanted.
976 */
977 Node *
978 coerce_to_boolean(ParseState *pstate, Node *node,
979 const char *constructName)
980 {
981 Oid inputTypeId = exprType(node);
982
983 if (inputTypeId != BOOLOID)
984 {
985 Node *newnode;
986
987 newnode = coerce_to_target_type(pstate, node, inputTypeId,
988 BOOLOID, -1,
989 COERCION_ASSIGNMENT,
990 COERCE_IMPLICIT_CAST,
991 -1);
992 if (newnode == NULL)
993 ereport(ERROR,
994 (errcode(ERRCODE_DATATYPE_MISMATCH),
995 /* translator: first %s is name of a SQL construct, eg WHERE */
996 errmsg("argument of %s must be type boolean, not type %s",
997 constructName, format_type_be(inputTypeId)),
998 parser_errposition(pstate, exprLocation(node))));
999 node = newnode;
1000 }
1001
1002 if (expression_returns_set(node))
1003 ereport(ERROR,
1004 (errcode(ERRCODE_DATATYPE_MISMATCH),
1005 /* translator: %s is name of a SQL construct, eg WHERE */
1006 errmsg("argument of %s must not return a set",
1007 constructName),
1008 parser_errposition(pstate, exprLocation(node))));
1009
1010 return node;
1011 }
1012
1013 /*
1014 * coerce_to_specific_type()
1015 * Coerce an argument of a construct that requires a specific data type.
1016 * Also check that input is not a set.
1017 *
1018 * Returns the possibly-transformed node tree.
1019 *
1020 * As with coerce_type, pstate may be NULL if no special unknown-Param
1021 * processing is wanted.
1022 */
1023 Node *
1024 coerce_to_specific_type(ParseState *pstate, Node *node,
1025 Oid targetTypeId,
1026 const char *constructName)
1027 {
1028 Oid inputTypeId = exprType(node);
1029
1030 if (inputTypeId != targetTypeId)
1031 {
1032 Node *newnode;
1033
1034 newnode = coerce_to_target_type(pstate, node, inputTypeId,
1035 targetTypeId, -1,
1036 COERCION_ASSIGNMENT,
1037 COERCE_IMPLICIT_CAST,
1038 -1);
1039 if (newnode == NULL)
1040 ereport(ERROR,
1041 (errcode(ERRCODE_DATATYPE_MISMATCH),
1042 /* translator: first %s is name of a SQL construct, eg LIMIT */
1043 errmsg("argument of %s must be type %s, not type %s",
1044 constructName,
1045 format_type_be(targetTypeId),
1046 format_type_be(inputTypeId)),
1047 parser_errposition(pstate, exprLocation(node))));
1048 node = newnode;
1049 }
1050
1051 if (expression_returns_set(node))
1052 ereport(ERROR,
1053 (errcode(ERRCODE_DATATYPE_MISMATCH),
1054 /* translator: %s is name of a SQL construct, eg LIMIT */
1055 errmsg("argument of %s must not return a set",
1056 constructName),
1057 parser_errposition(pstate, exprLocation(node))));
1058
1059 return node;
1060 }
1061
1062
1063 /*
1064 * parser_coercion_errposition - report coercion error location, if possible
1065 *
1066 * We prefer to point at the coercion request (CAST, ::, etc) if possible;
1067 * but there may be no such location in the case of an implicit coercion.
1068 * In that case point at the input expression.
1069 *
1070 * XXX possibly this is more generally useful than coercion errors;
1071 * if so, should rename and place with parser_errposition.
1072 */
1073 int
1074 parser_coercion_errposition(ParseState *pstate,
1075 int coerce_location,
1076 Node *input_expr)
1077 {
1078 if (coerce_location >= 0)
1079 return parser_errposition(pstate, coerce_location);
1080 else
1081 return parser_errposition(pstate, exprLocation(input_expr));
1082 }
1083
1084
1085 /*
1086 * select_common_type()
1087 * Determine the common supertype of a list of input expressions.
1088 * This is used for determining the output type of CASE, UNION,
1089 * and similar constructs.
1090 *
1091 * 'exprs' is a *nonempty* list of expressions. Note that earlier items
1092 * in the list will be preferred if there is doubt.
1093 * 'context' is a phrase to use in the error message if we fail to select
1094 * a usable type. Pass NULL to have the routine return InvalidOid
1095 * rather than throwing an error on failure.
1096 * 'which_expr': if not NULL, receives a pointer to the particular input
1097 * expression from which the result type was taken.
1098 */
1099 Oid
1100 select_common_type(ParseState *pstate, List *exprs, const char *context,
1101 Node **which_expr)
1102 {
1103 Node *pexpr;
1104 Oid ptype;
1105 TYPCATEGORY pcategory;
1106 bool pispreferred;
1107 ListCell *lc;
1108
1109 Assert(exprs != NIL);
1110 pexpr = (Node *) linitial(exprs);
1111 lc = lnext(list_head(exprs));
1112 ptype = exprType(pexpr);
1113
1114 /*
1115 * If all input types are valid and exactly the same, just pick that type.
1116 * This is the only way that we will resolve the result as being a domain
1117 * type; otherwise domains are smashed to their base types for comparison.
1118 */
1119 if (ptype != UNKNOWNOID)
1120 {
1121 for_each_cell(lc, lc)
1122 {
1123 Node *nexpr = (Node *) lfirst(lc);
1124 Oid ntype = exprType(nexpr);
1125
1126 if (ntype != ptype)
1127 break;
1128 }
1129 if (lc == NULL) /* got to the end of the list? */
1130 {
1131 if (which_expr)
1132 *which_expr = pexpr;
1133 return ptype;
1134 }
1135 }
1136
1137 /*
1138 * Nope, so set up for the full algorithm. Note that at this point,
1139 * lc points to the first list item with type different from pexpr's;
1140 * we need not re-examine any items the previous loop advanced over.
1141 */
1142 ptype = getBaseType(ptype);
1143 get_type_category_preferred(ptype, &pcategory, &pispreferred);
1144
1145 for_each_cell(lc, lc)
1146 {
1147 Node *nexpr = (Node *) lfirst(lc);
1148 Oid ntype = getBaseType(exprType(nexpr));
1149
1150 /* move on to next one if no new information... */
1151 if (ntype != UNKNOWNOID && ntype != ptype)
1152 {
1153 TYPCATEGORY ncategory;
1154 bool nispreferred;
1155
1156 get_type_category_preferred(ntype, &ncategory, &nispreferred);
1157 if (ptype == UNKNOWNOID)
1158 {
1159 /* so far, only unknowns so take anything... */
1160 pexpr = nexpr;
1161 ptype = ntype;
1162 pcategory = ncategory;
1163 pispreferred = nispreferred;
1164 }
1165 else if (ncategory != pcategory)
1166 {
1167 /*
1168 * both types in different categories? then not much hope...
1169 */
1170 if (context == NULL)
1171 return InvalidOid;
1172 ereport(ERROR,
1173 (errcode(ERRCODE_DATATYPE_MISMATCH),
1174 /*------
1175 translator: first %s is name of a SQL construct, eg CASE */
1176 errmsg("%s types %s and %s cannot be matched",
1177 context,
1178 format_type_be(ptype),
1179 format_type_be(ntype)),
1180 parser_errposition(pstate, exprLocation(nexpr))));
1181 }
1182 else if (!pispreferred &&
1183 can_coerce_type(1, &ptype, &ntype, COERCION_IMPLICIT) &&
1184 !can_coerce_type(1, &ntype, &ptype, COERCION_IMPLICIT))
1185 {
1186 /*
1187 * take new type if can coerce to it implicitly but not the
1188 * other way; but if we have a preferred type, stay on it.
1189 */
1190 pexpr = nexpr;
1191 ptype = ntype;
1192 pcategory = ncategory;
1193 pispreferred = nispreferred;
1194 }
1195 }
1196 }
1197
1198 /*
1199 * If all the inputs were UNKNOWN type --- ie, unknown-type literals ---
1200 * then resolve as type TEXT. This situation comes up with constructs
1201 * like SELECT (CASE WHEN foo THEN 'bar' ELSE 'baz' END); SELECT 'foo'
1202 * UNION SELECT 'bar'; It might seem desirable to leave the construct's
1203 * output type as UNKNOWN, but that really doesn't work, because we'd
1204 * probably end up needing a runtime coercion from UNKNOWN to something
1205 * else, and we usually won't have it. We need to coerce the unknown
1206 * literals while they are still literals, so a decision has to be made
1207 * now.
1208 */
1209 if (ptype == UNKNOWNOID)
1210 ptype = TEXTOID;
1211
1212 if (which_expr)
1213 *which_expr = pexpr;
1214 return ptype;
1215 }
1216
1217 /*
1218 * coerce_to_common_type()
1219 * Coerce an expression to the given type.
1220 *
1221 * This is used following select_common_type() to coerce the individual
1222 * expressions to the desired type. 'context' is a phrase to use in the
1223 * error message if we fail to coerce.
1224 *
1225 * As with coerce_type, pstate may be NULL if no special unknown-Param
1226 * processing is wanted.
1227 */
1228 Node *
1229 coerce_to_common_type(ParseState *pstate, Node *node,
1230 Oid targetTypeId, const char *context)
1231 {
1232 Oid inputTypeId = exprType(node);
1233
1234 if (inputTypeId == targetTypeId)
1235 return node; /* no work */
1236 if (can_coerce_type(1, &inputTypeId, &targetTypeId, COERCION_IMPLICIT))
1237 node = coerce_type(pstate, node, inputTypeId, targetTypeId, -1,
1238 COERCION_IMPLICIT, COERCE_IMPLICIT_CAST, -1);
1239 else
1240 ereport(ERROR,
1241 (errcode(ERRCODE_CANNOT_COERCE),
1242 /* translator: first %s is name of a SQL construct, eg CASE */
1243 errmsg("%s could not convert type %s to %s",
1244 context,
1245 format_type_be(inputTypeId),
1246 format_type_be(targetTypeId)),
1247 parser_errposition(pstate, exprLocation(node))));
1248 return node;
1249 }
1250
1251 /*
1252 * check_generic_type_consistency()
1253 * Are the actual arguments potentially compatible with a
1254 * polymorphic function?
1255 *
1256 * The argument consistency rules are:
1257 *
1258 * 1) All arguments declared ANYARRAY must have matching datatypes,
1259 * and must in fact be varlena arrays.
1260 * 2) All arguments declared ANYELEMENT must have matching datatypes.
1261 * 3) If there are arguments of both ANYELEMENT and ANYARRAY, make sure
1262 * the actual ANYELEMENT datatype is in fact the element type for
1263 * the actual ANYARRAY datatype.
1264 * 4) ANYENUM is treated the same as ANYELEMENT except that if it is used
1265 * (alone or in combination with plain ANYELEMENT), we add the extra
1266 * condition that the ANYELEMENT type must be an enum.
1267 * 5) ANYNONARRAY is treated the same as ANYELEMENT except that if it is used,
1268 * we add the extra condition that the ANYELEMENT type must not be an array.
1269 * (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
1270 * is an extra restriction if not.)
1271 *
1272 * If we have UNKNOWN input (ie, an untyped literal) for any polymorphic
1273 * argument, assume it is okay.
1274 *
1275 * If an input is of type ANYARRAY (ie, we know it's an array, but not
1276 * what element type), we will accept it as a match to an argument declared
1277 * ANYARRAY, so long as we don't have to determine an element type ---
1278 * that is, so long as there is no use of ANYELEMENT. This is mostly for
1279 * backwards compatibility with the pre-7.4 behavior of ANYARRAY.
1280 *
1281 * We do not ereport here, but just return FALSE if a rule is violated.
1282 */
1283 bool
1284 check_generic_type_consistency(Oid *actual_arg_types,
1285 Oid *declared_arg_types,
1286 int nargs)
1287 {
1288 int j;
1289 Oid elem_typeid = InvalidOid;
1290 Oid array_typeid = InvalidOid;
1291 Oid array_typelem;
1292 bool have_anyelement = false;
1293 bool have_anynonarray = false;
1294 bool have_anyenum = false;
1295
1296 /*
1297 * Loop through the arguments to see if we have any that are polymorphic.
1298 * If so, require the actual types to be consistent.
1299 */
1300 for (j = 0; j < nargs; j++)
1301 {
1302 Oid decl_type = declared_arg_types[j];
1303 Oid actual_type = actual_arg_types[j];
1304
1305 if (decl_type == ANYELEMENTOID ||
1306 decl_type == ANYNONARRAYOID ||
1307 decl_type == ANYENUMOID)
1308 {
1309 have_anyelement = true;
1310 if (decl_type == ANYNONARRAYOID)
1311 have_anynonarray = true;
1312 else if (decl_type == ANYENUMOID)
1313 have_anyenum = true;
1314 if (actual_type == UNKNOWNOID)
1315 continue;
1316 if (OidIsValid(elem_typeid) && actual_type != elem_typeid)
1317 return false;
1318 elem_typeid = actual_type;
1319 }
1320 else if (decl_type == ANYARRAYOID)
1321 {
1322 if (actual_type == UNKNOWNOID)
1323 continue;
1324 if (OidIsValid(array_typeid) && actual_type != array_typeid)
1325 return false;
1326 array_typeid = actual_type;
1327 }
1328 }
1329
1330 /* Get the element type based on the array type, if we have one */
1331 if (OidIsValid(array_typeid))
1332 {
1333 if (array_typeid == ANYARRAYOID)
1334 {
1335 /* Special case for ANYARRAY input: okay iff no ANYELEMENT */
1336 if (have_anyelement)
1337 return false;
1338 return true;
1339 }
1340
1341 array_typelem = get_element_type(array_typeid);
1342 if (!OidIsValid(array_typelem))
1343 return false; /* should be an array, but isn't */
1344
1345 if (!OidIsValid(elem_typeid))
1346 {
1347 /*
1348 * if we don't have an element type yet, use the one we just got
1349 */
1350 elem_typeid = array_typelem;
1351 }
1352 else if (array_typelem != elem_typeid)
1353 {
1354 /* otherwise, they better match */
1355 return false;
1356 }
1357 }
1358
1359 if (have_anynonarray)
1360 {
1361 /* require the element type to not be an array */
1362 if (type_is_array(elem_typeid))
1363 return false;
1364 }
1365
1366 if (have_anyenum)
1367 {
1368 /* require the element type to be an enum */
1369 if (!type_is_enum(elem_typeid))
1370 return false;
1371 }
1372
1373 /* Looks valid */
1374 return true;
1375 }
1376
1377 /*
1378 * enforce_generic_type_consistency()
1379 * Make sure a polymorphic function is legally callable, and
1380 * deduce actual argument and result types.
1381 *
1382 * If any polymorphic pseudotype is used in a function's arguments or
1383 * return type, we make sure the actual data types are consistent with
1384 * each other. The argument consistency rules are shown above for
1385 * check_generic_type_consistency().
1386 *
1387 * If we have UNKNOWN input (ie, an untyped literal) for any polymorphic
1388 * argument, we attempt to deduce the actual type it should have. If
1389 * successful, we alter that position of declared_arg_types[] so that
1390 * make_fn_arguments will coerce the literal to the right thing.
1391 *
1392 * Rules are applied to the function's return type (possibly altering it)
1393 * if it is declared as a polymorphic type:
1394 *
1395 * 1) If return type is ANYARRAY, and any argument is ANYARRAY, use the
1396 * argument's actual type as the function's return type.
1397 * 2) If return type is ANYARRAY, no argument is ANYARRAY, but any argument
1398 * is ANYELEMENT, use the actual type of the argument to determine
1399 * the function's return type, i.e. the element type's corresponding
1400 * array type.
1401 * 3) If return type is ANYARRAY, no argument is ANYARRAY or ANYELEMENT,
1402 * generate an ERROR. This condition is prevented by CREATE FUNCTION
1403 * and is therefore not expected here.
1404 * 4) If return type is ANYELEMENT, and any argument is ANYELEMENT, use the
1405 * argument's actual type as the function's return type.
1406 * 5) If return type is ANYELEMENT, no argument is ANYELEMENT, but any
1407 * argument is ANYARRAY, use the actual type of the argument to determine
1408 * the function's return type, i.e. the array type's corresponding
1409 * element type.
1410 * 6) If return type is ANYELEMENT, no argument is ANYARRAY or ANYELEMENT,
1411 * generate an ERROR. This condition is prevented by CREATE FUNCTION
1412 * and is therefore not expected here.
1413 * 7) ANYENUM is treated the same as ANYELEMENT except that if it is used
1414 * (alone or in combination with plain ANYELEMENT), we add the extra
1415 * condition that the ANYELEMENT type must be an enum.
1416 * 8) ANYNONARRAY is treated the same as ANYELEMENT except that if it is used,
1417 * we add the extra condition that the ANYELEMENT type must not be an array.
1418 * (This is a no-op if used in combination with ANYARRAY or ANYENUM, but
1419 * is an extra restriction if not.)
1420 *
1421 * When allow_poly is false, we are not expecting any of the actual_arg_types
1422 * to be polymorphic, and we should not return a polymorphic result type
1423 * either. When allow_poly is true, it is okay to have polymorphic "actual"
1424 * arg types, and we can return ANYARRAY or ANYELEMENT as the result. (This
1425 * case is currently used only to check compatibility of an aggregate's
1426 * declaration with the underlying transfn.)
1427 */
1428 Oid
1429 enforce_generic_type_consistency(Oid *actual_arg_types,
1430 Oid *declared_arg_types,
1431 int nargs,
1432 Oid rettype,
1433 bool allow_poly)
1434 {
1435 int j;
1436 bool have_generics = false;
1437 bool have_unknowns = false;
1438 Oid elem_typeid = InvalidOid;
1439 Oid array_typeid = InvalidOid;
1440 Oid array_typelem;
1441 bool have_anynonarray = (rettype == ANYNONARRAYOID);
1442 bool have_anyenum = (rettype == ANYENUMOID);
1443
1444 /*
1445 * Loop through the arguments to see if we have any that are polymorphic.
1446 * If so, require the actual types to be consistent.
1447 */
1448 for (j = 0; j < nargs; j++)
1449 {
1450 Oid decl_type = declared_arg_types[j];
1451 Oid actual_type = actual_arg_types[j];
1452
1453 if (decl_type == ANYELEMENTOID ||
1454 decl_type == ANYNONARRAYOID ||
1455 decl_type == ANYENUMOID)
1456 {
1457 have_generics = true;
1458 if (decl_type == ANYNONARRAYOID)
1459 have_anynonarray = true;
1460 else if (decl_type == ANYENUMOID)
1461 have_anyenum = true;
1462 if (actual_type == UNKNOWNOID)
1463 {
1464 have_unknowns = true;
1465 continue;
1466 }
1467 if (allow_poly && decl_type == actual_type)
1468 continue; /* no new information here */
1469 if (OidIsValid(elem_typeid) && actual_type != elem_typeid)
1470 ereport(ERROR,
1471 (errcode(ERRCODE_DATATYPE_MISMATCH),
1472 errmsg("arguments declared \"anyelement\" are not all alike"),
1473 errdetail("%s versus %s",
1474 format_type_be(elem_typeid),
1475 format_type_be(actual_type))));
1476 elem_typeid = actual_type;
1477 }
1478 else if (decl_type == ANYARRAYOID)
1479 {
1480 have_generics = true;
1481 if (actual_type == UNKNOWNOID)
1482 {
1483 have_unknowns = true;
1484 continue;
1485 }
1486 if (allow_poly && decl_type == actual_type)
1487 continue; /* no new information here */
1488 if (OidIsValid(array_typeid) && actual_type != array_typeid)
1489 ereport(ERROR,
1490 (errcode(ERRCODE_DATATYPE_MISMATCH),
1491 errmsg("arguments declared \"anyarray\" are not all alike"),
1492 errdetail("%s versus %s",
1493 format_type_be(array_typeid),
1494 format_type_be(actual_type))));
1495 array_typeid = actual_type;
1496 }
1497 }
1498
1499 /*
1500 * Fast Track: if none of the arguments are polymorphic, return the
1501 * unmodified rettype. We assume it can't be polymorphic either.
1502 */
1503 if (!have_generics)
1504 return rettype;
1505
1506 /* Get the element type based on the array type, if we have one */
1507 if (OidIsValid(array_typeid))
1508 {
1509 array_typelem = get_element_type(array_typeid);
1510 if (!OidIsValid(array_typelem))
1511 ereport(ERROR,
1512 (errcode(ERRCODE_DATATYPE_MISMATCH),
1513 errmsg("argument declared \"anyarray\" is not an array but type %s",
1514 format_type_be(array_typeid))));
1515
1516 if (!OidIsValid(elem_typeid))
1517 {
1518 /*
1519 * if we don't have an element type yet, use the one we just got
1520 */
1521 elem_typeid = array_typelem;
1522 }
1523 else if (array_typelem != elem_typeid)
1524 {
1525 /* otherwise, they better match */
1526 ereport(ERROR,
1527 (errcode(ERRCODE_DATATYPE_MISMATCH),
1528 errmsg("argument declared \"anyarray\" is not consistent with argument declared \"anyelement\""),
1529 errdetail("%s versus %s",
1530 format_type_be(array_typeid),
1531 format_type_be(elem_typeid))));
1532 }
1533 }
1534 else if (!OidIsValid(elem_typeid))
1535 {
1536 if (allow_poly)
1537 {
1538 array_typeid = ANYARRAYOID;
1539 elem_typeid = ANYELEMENTOID;
1540 }
1541 else
1542 {
1543 /* Only way to get here is if all the generic args are UNKNOWN */
1544 ereport(ERROR,
1545 (errcode(ERRCODE_DATATYPE_MISMATCH),
1546 errmsg("could not determine polymorphic type because input has type \"unknown\"")));
1547 }
1548 }
1549
1550 if (have_anynonarray && elem_typeid != ANYELEMENTOID)
1551 {
1552 /* require the element type to not be an array */
1553 if (type_is_array(elem_typeid))
1554 ereport(ERROR,
1555 (errcode(ERRCODE_DATATYPE_MISMATCH),
1556 errmsg("type matched to anynonarray is an array type: %s",
1557 format_type_be(elem_typeid))));
1558 }
1559
1560 if (have_anyenum && elem_typeid != ANYELEMENTOID)
1561 {
1562 /* require the element type to be an enum */
1563 if (!type_is_enum(elem_typeid))
1564 ereport(ERROR,
1565 (errcode(ERRCODE_DATATYPE_MISMATCH),
1566 errmsg("type matched to anyenum is not an enum type: %s",
1567 format_type_be(elem_typeid))));
1568 }
1569
1570 /*
1571 * If we had any unknown inputs, re-scan to assign correct types
1572 */
1573 if (have_unknowns)
1574 {
1575 for (j = 0; j < nargs; j++)
1576 {
1577 Oid decl_type = declared_arg_types[j];
1578 Oid actual_type = actual_arg_types[j];
1579
1580 if (actual_type != UNKNOWNOID)
1581 continue;
1582
1583 if (decl_type == ANYELEMENTOID ||
1584 decl_type == ANYNONARRAYOID ||
1585 decl_type == ANYENUMOID)
1586 declared_arg_types[j] = elem_typeid;
1587 else if (decl_type == ANYARRAYOID)
1588 {
1589 if (!OidIsValid(array_typeid))
1590 {
1591 array_typeid = get_array_type(elem_typeid);
1592 if (!OidIsValid(array_typeid))
1593 ereport(ERROR,
1594 (errcode(ERRCODE_UNDEFINED_OBJECT),
1595 errmsg("could not find array type for data type %s",
1596 format_type_be(elem_typeid))));
1597 }
1598 declared_arg_types[j] = array_typeid;
1599 }
1600 }
1601 }
1602
1603 /* if we return ANYARRAY use the appropriate argument type */
1604 if (rettype == ANYARRAYOID)
1605 {
1606 if (!OidIsValid(array_typeid))
1607 {
1608 array_typeid = get_array_type(elem_typeid);
1609 if (!OidIsValid(array_typeid))
1610 ereport(ERROR,
1611 (errcode(ERRCODE_UNDEFINED_OBJECT),
1612 errmsg("could not find array type for data type %s",
1613 format_type_be(elem_typeid))));
1614 }
1615 return array_typeid;
1616 }
1617
1618 /* if we return ANYELEMENT use the appropriate argument type */
1619 if (rettype == ANYELEMENTOID ||
1620 rettype == ANYNONARRAYOID ||
1621 rettype == ANYENUMOID)
1622 return elem_typeid;
1623
1624 /* we don't return a generic type; send back the original return type */
1625 return rettype;
1626 }
1627
1628 /*
1629 * resolve_generic_type()
1630 * Deduce an individual actual datatype on the assumption that
1631 * the rules for polymorphic types are being followed.
1632 *
1633 * declared_type is the declared datatype we want to resolve.
1634 * context_actual_type is the actual input datatype to some argument
1635 * that has declared datatype context_declared_type.
1636 *
1637 * If declared_type isn't polymorphic, we just return it. Otherwise,
1638 * context_declared_type must be polymorphic, and we deduce the correct
1639 * return type based on the relationship of the two polymorphic types.
1640 */
1641 Oid
1642 resolve_generic_type(Oid declared_type,
1643 Oid context_actual_type,
1644 Oid context_declared_type)
1645 {
1646 if (declared_type == ANYARRAYOID)
1647 {
1648 if (context_declared_type == ANYARRAYOID)
1649 {
1650 /* Use actual type, but it must be an array */
1651 Oid array_typelem = get_element_type(context_actual_type);
1652
1653 if (!OidIsValid(array_typelem))
1654 ereport(ERROR,
1655 (errcode(ERRCODE_DATATYPE_MISMATCH),
1656 errmsg("argument declared \"anyarray\" is not an array but type %s",
1657 format_type_be(context_actual_type))));
1658 return context_actual_type;
1659 }
1660 else if (context_declared_type == ANYELEMENTOID ||
1661 context_declared_type == ANYNONARRAYOID ||
1662 context_declared_type == ANYENUMOID)
1663 {
1664 /* Use the array type corresponding to actual type */
1665 Oid array_typeid = get_array_type(context_actual_type);
1666
1667 if (!OidIsValid(array_typeid))
1668 ereport(ERROR,
1669 (errcode(ERRCODE_UNDEFINED_OBJECT),
1670 errmsg("could not find array type for data type %s",
1671 format_type_be(context_actual_type))));
1672 return array_typeid;
1673 }
1674 }
1675 else if (declared_type == ANYELEMENTOID ||
1676 declared_type == ANYNONARRAYOID ||
1677 declared_type == ANYENUMOID)
1678 {
1679 if (context_declared_type == ANYARRAYOID)
1680 {
1681 /* Use the element type corresponding to actual type */
1682 Oid array_typelem = get_element_type(context_actual_type);
1683
1684 if (!OidIsValid(array_typelem))
1685 ereport(ERROR,
1686 (errcode(ERRCODE_DATATYPE_MISMATCH),
1687 errmsg("argument declared \"anyarray\" is not an array but type %s",
1688 format_type_be(context_actual_type))));
1689 return array_typelem;
1690 }
1691 else if (context_declared_type == ANYELEMENTOID ||
1692 context_declared_type == ANYNONARRAYOID ||
1693 context_declared_type == ANYENUMOID)
1694 {
1695 /* Use the actual type; it doesn't matter if array or not */
1696 return context_actual_type;
1697 }
1698 }
1699 else
1700 {
1701 /* declared_type isn't polymorphic, so return it as-is */
1702 return declared_type;
1703 }
1704 /* If we get here, declared_type is polymorphic and context isn't */
1705 /* NB: this is a calling-code logic error, not a user error */
1706 elog(ERROR, "could not determine polymorphic type because context isn't polymorphic");
1707 return InvalidOid; /* keep compiler quiet */
1708 }
1709
1710
1711 /* TypeCategory()
1712 * Assign a category to the specified type OID.
1713 *
1714 * NB: this must not return TYPCATEGORY_INVALID.
1715 */
1716 TYPCATEGORY
1717 TypeCategory(Oid type)
1718 {
1719 char typcategory;
1720 bool typispreferred;
1721
1722 get_type_category_preferred(type, &typcategory, &typispreferred);
1723 Assert(typcategory != TYPCATEGORY_INVALID);
1724 return (TYPCATEGORY) typcategory;
1725 }
1726
1727
1728 /* IsPreferredType()
1729 * Check if this type is a preferred type for the given category.
1730 *
1731 * If category is TYPCATEGORY_INVALID, then we'll return TRUE for preferred
1732 * types of any category; otherwise, only for preferred types of that
1733 * category.
1734 */
1735 bool
1736 IsPreferredType(TYPCATEGORY category, Oid type)
1737 {
1738 char typcategory;
1739 bool typispreferred;
1740
1741 get_type_category_preferred(type, &typcategory, &typispreferred);
1742 if (category == typcategory || category == TYPCATEGORY_INVALID)
1743 return typispreferred;
1744 else
1745 return false;
1746 }
1747
1748
1749 /* IsBinaryCoercible()
1750 * Check if srctype is binary-coercible to targettype.
1751 *
1752 * This notion allows us to cheat and directly exchange values without
1753 * going through the trouble of calling a conversion function. Note that
1754 * in general, this should only be an implementation shortcut. Before 7.4,
1755 * this was also used as a heuristic for resolving overloaded functions and
1756 * operators, but that's basically a bad idea.
1757 *
1758 * As of 7.3, binary coercibility isn't hardwired into the code anymore.
1759 * We consider two types binary-coercible if there is an implicitly
1760 * invokable, no-function-needed pg_cast entry. Also, a domain is always
1761 * binary-coercible to its base type, though *not* vice versa (in the other
1762 * direction, one must apply domain constraint checks before accepting the
1763 * value as legitimate). We also need to special-case various polymorphic
1764 * types.
1765 *
1766 * This function replaces IsBinaryCompatible(), which was an inherently
1767 * symmetric test. Since the pg_cast entries aren't necessarily symmetric,
1768 * the order of the operands is now significant.
1769 */
1770 bool
1771 IsBinaryCoercible(Oid srctype, Oid targettype)
1772 {
1773 HeapTuple tuple;
1774 Form_pg_cast castForm;
1775 bool result;
1776
1777 /* Fast path if same type */
1778 if (srctype == targettype)
1779 return true;
1780
1781 /* If srctype is a domain, reduce to its base type */
1782 if (OidIsValid(srctype))
1783 srctype = getBaseType(srctype);
1784
1785 /* Somewhat-fast path for domain -> base type case */
1786 if (srctype == targettype)
1787 return true;
1788
1789 /* Also accept any array type as coercible to ANYARRAY */
1790 if (targettype == ANYARRAYOID)
1791 if (type_is_array(srctype))
1792 return true;
1793
1794 /* Also accept any non-array type as coercible to ANYNONARRAY */
1795 if (targettype == ANYNONARRAYOID)
1796 if (!type_is_array(srctype))
1797 return true;
1798
1799 /* Also accept any enum type as coercible to ANYENUM */
1800 if (targettype == ANYENUMOID)
1801 if (type_is_enum(srctype))
1802 return true;
1803
1804 /* Also accept any composite type as coercible to RECORD */
1805 if (targettype == RECORDOID)
1806 if (ISCOMPLEX(srctype))
1807 return true;
1808
1809 /* Also accept any composite array type as coercible to RECORD[] */
1810 if (targettype == RECORDARRAYOID)
1811 if (is_complex_array(srctype))
1812 return true;
1813
1814 /* Else look in pg_cast */
1815 tuple = SearchSysCache(CASTSOURCETARGET,
1816 ObjectIdGetDatum(srctype),
1817 ObjectIdGetDatum(targettype),
1818 0, 0);
1819 if (!HeapTupleIsValid(tuple))
1820 return false; /* no cast */
1821 castForm = (Form_pg_cast) GETSTRUCT(tuple);
1822
1823 result = (castForm->castfunc == InvalidOid &&
1824 castForm->castcontext == COERCION_CODE_IMPLICIT);
1825
1826 ReleaseSysCache(tuple);
1827
1828 return result;
1829 }
1830
1831
1832 /*
1833 * find_coercion_pathway
1834 * Look for a coercion pathway between two types.
1835 *
1836 * Currently, this deals only with scalar-type cases; it does not consider
1837 * polymorphic types nor casts between composite types. (Perhaps fold
1838 * those in someday?)
1839 *
1840 * ccontext determines the set of available casts.
1841 *
1842 * The possible result codes are:
1843 * COERCION_PATH_NONE: failed to find any coercion pathway
1844 * *funcid is set to InvalidOid
1845 * COERCION_PATH_FUNC: apply the coercion function returned in *funcid
1846 * COERCION_PATH_RELABELTYPE: binary-compatible cast, no function needed
1847 * *funcid is set to InvalidOid
1848 * COERCION_PATH_ARRAYCOERCE: need an ArrayCoerceExpr node
1849 * *funcid is set to the element cast function, or InvalidOid
1850 * if the array elements are binary-compatible
1851 * COERCION_PATH_COERCEVIAIO: need a CoerceViaIO node
1852 * *funcid is set to InvalidOid
1853 *
1854 * Note: COERCION_PATH_RELABELTYPE does not necessarily mean that no work is
1855 * needed to do the coercion; if the target is a domain then we may need to
1856 * apply domain constraint checking. If you want to check for a zero-effort
1857 * conversion then use IsBinaryCoercible().
1858 */
1859 CoercionPathType
1860 find_coercion_pathway(Oid targetTypeId, Oid sourceTypeId,
1861 CoercionContext ccontext,
1862 Oid *funcid)
1863 {
1864 CoercionPathType result = COERCION_PATH_NONE;
1865 HeapTuple tuple;
1866
1867 *funcid = InvalidOid;
1868
1869 /* Perhaps the types are domains; if so, look at their base types */
1870 if (OidIsValid(sourceTypeId))
1871 sourceTypeId = getBaseType(sourceTypeId);
1872 if (OidIsValid(targetTypeId))
1873 targetTypeId = getBaseType(targetTypeId);
1874
1875 /* Domains are always coercible to and from their base type */
1876 if (sourceTypeId == targetTypeId)
1877 return COERCION_PATH_RELABELTYPE;
1878
1879 /* Look in pg_cast */
1880 tuple = SearchSysCache(CASTSOURCETARGET,
1881 ObjectIdGetDatum(sourceTypeId),
1882 ObjectIdGetDatum(targetTypeId),
1883 0, 0);
1884
1885 if (HeapTupleIsValid(tuple))
1886 {
1887 Form_pg_cast castForm = (Form_pg_cast) GETSTRUCT(tuple);
1888 CoercionContext castcontext;
1889
1890 /* convert char value for castcontext to CoercionContext enum */
1891 switch (castForm->castcontext)
1892 {
1893 case COERCION_CODE_IMPLICIT:
1894 castcontext = COERCION_IMPLICIT;
1895 break;
1896 case COERCION_CODE_ASSIGNMENT:
1897 castcontext = COERCION_ASSIGNMENT;
1898 break;
1899 case COERCION_CODE_EXPLICIT:
1900 castcontext = COERCION_EXPLICIT;
1901 break;
1902 default:
1903 elog(ERROR, "unrecognized castcontext: %d",
1904 (int) castForm->castcontext);
1905 castcontext = 0; /* keep compiler quiet */
1906 break;
1907 }
1908
1909 /* Rely on ordering of enum for correct behavior here */
1910 if (ccontext >= castcontext)
1911 {
1912 switch (castForm->castmethod)
1913 {
1914 case COERCION_METHOD_FUNCTION:
1915 result = COERCION_PATH_FUNC;
1916 *funcid = castForm->castfunc;
1917 break;
1918 case COERCION_METHOD_INOUT:
1919 result = COERCION_PATH_COERCEVIAIO;
1920 break;
1921 case COERCION_METHOD_BINARY:
1922 result = COERCION_PATH_RELABELTYPE;
1923 break;
1924 default:
1925 elog(ERROR, "unrecognized castmethod: %d",
1926 (int) castForm->castmethod);
1927 break;
1928 }
1929 }
1930
1931 ReleaseSysCache(tuple);
1932 }
1933 else
1934 {
1935 /*
1936 * If there's no pg_cast entry, perhaps we are dealing with a pair of
1937 * array types. If so, and if the element types have a suitable cast,
1938 * report that we can coerce with an ArrayCoerceExpr.
1939 *
1940 * Hack: disallow coercions to oidvector and int2vector, which
1941 * otherwise tend to capture coercions that should go to "real" array
1942 * types. We want those types to be considered "real" arrays for many
1943 * purposes, but not this one. (Also, ArrayCoerceExpr isn't
1944 * guaranteed to produce an output that meets the restrictions of
1945 * these datatypes, such as being 1-dimensional.)
1946 */
1947 if (targetTypeId != OIDVECTOROID && targetTypeId != INT2VECTOROID)
1948 {
1949 Oid targetElem;
1950 Oid sourceElem;
1951
1952 if ((targetElem = get_element_type(targetTypeId)) != InvalidOid &&
1953 (sourceElem = get_element_type(sourceTypeId)) != InvalidOid)
1954 {
1955 CoercionPathType elempathtype;
1956 Oid elemfuncid;
1957
1958 elempathtype = find_coercion_pathway(targetElem,
1959 sourceElem,
1960 ccontext,
1961 &elemfuncid);
1962 if (elempathtype != COERCION_PATH_NONE &&
1963 elempathtype != COERCION_PATH_ARRAYCOERCE)
1964 {
1965 *funcid = elemfuncid;
1966 if (elempathtype == COERCION_PATH_COERCEVIAIO)
1967 result = COERCION_PATH_COERCEVIAIO;
1968 else
1969 result = COERCION_PATH_ARRAYCOERCE;
1970 }
1971 }
1972 }
1973
1974 /*
1975 * If we still haven't found a possibility, consider automatic casting
1976 * using I/O functions. We allow assignment casts to string types
1977 * and explicit casts from string types to be handled this way. (The
1978 * CoerceViaIO mechanism is a lot more general than that, but this is
1979 * all we want to allow in the absence of a pg_cast entry.) It would
1980 * probably be better to insist on explicit casts in both directions,
1981 * but this is a compromise to preserve something of the pre-8.3
1982 * behavior that many types had implicit (yipes!) casts to text.
1983 */
1984 if (result == COERCION_PATH_NONE)
1985 {
1986 if (ccontext >= COERCION_ASSIGNMENT &&
1987 TypeCategory(targetTypeId) == TYPCATEGORY_STRING)
1988 result = COERCION_PATH_COERCEVIAIO;
1989 else if (ccontext >= COERCION_EXPLICIT &&
1990 TypeCategory(sourceTypeId) == TYPCATEGORY_STRING)
1991 result = COERCION_PATH_COERCEVIAIO;
1992 }
1993 }
1994
1995 return result;
1996 }
1997
1998
1999 /*
2000 * find_typmod_coercion_function -- does the given type need length coercion?
2001 *
2002 * If the target type possesses a pg_cast function from itself to itself,
2003 * it must need length coercion.
2004 *
2005 * "bpchar" (ie, char(N)) and "numeric" are examples of such types.
2006 *
2007 * If the given type is a varlena array type, we do not look for a coercion
2008 * function associated directly with the array type, but instead look for
2009 * one associated with the element type. An ArrayCoerceExpr node must be
2010 * used to apply such a function.
2011 *
2012 * We use the same result enum as find_coercion_pathway, but the only possible
2013 * result codes are:
2014 * COERCION_PATH_NONE: no length coercion needed
2015 * COERCION_PATH_FUNC: apply the function returned in *funcid
2016 * COERCION_PATH_ARRAYCOERCE: apply the function using ArrayCoerceExpr
2017 */
2018 CoercionPathType
2019 find_typmod_coercion_function(Oid typeId,
2020 Oid *funcid)
2021 {
2022 CoercionPathType result;
2023 Type targetType;
2024 Form_pg_type typeForm;
2025 HeapTuple tuple;
2026
2027 *funcid = InvalidOid;
2028 result = COERCION_PATH_FUNC;
2029
2030 targetType = typeidType(typeId);
2031 typeForm = (Form_pg_type) GETSTRUCT(targetType);
2032
2033 /* Check for a varlena array type (and not a domain) */
2034 if (typeForm->typelem != InvalidOid &&
2035 typeForm->typlen == -1 &&
2036 typeForm->typtype != TYPTYPE_DOMAIN)
2037 {
2038 /* Yes, switch our attention to the element type */
2039 typeId = typeForm->typelem;
2040 result = COERCION_PATH_ARRAYCOERCE;
2041 }
2042 ReleaseSysCache(targetType);
2043
2044 /* Look in pg_cast */
2045 tuple = SearchSysCache(CASTSOURCETARGET,
2046 ObjectIdGetDatum(typeId),
2047 ObjectIdGetDatum(typeId),
2048 0, 0);
2049
2050 if (HeapTupleIsValid(tuple))
2051 {
2052 Form_pg_cast castForm = (Form_pg_cast) GETSTRUCT(tuple);
2053
2054 *funcid = castForm->castfunc;
2055 ReleaseSysCache(tuple);
2056 }
2057
2058 if (!OidIsValid(*funcid))
2059 result = COERCION_PATH_NONE;
2060
2061 return result;
2062 }
2063
2064 /*
2065 * is_complex_array
2066 * Is this type an array of composite?
2067 *
2068 * Note: this will not return true for record[]; check for RECORDARRAYOID
2069 * separately if needed.
2070 */
2071 static bool
2072 is_complex_array(Oid typid)
2073 {
2074 Oid elemtype = get_element_type(typid);
2075
2076 return (OidIsValid(elemtype) && ISCOMPLEX(elemtype));
2077 }
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