/*------------------------------------------------------------------------- * * parse_func.c * handle function calls in parser * * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.108 2001/05/19 01:57:11 momjian Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "access/genam.h" #include "access/heapam.h" #include "catalog/catname.h" #include "catalog/indexing.h" #include "catalog/pg_aggregate.h" #include "catalog/pg_inherits.h" #include "catalog/pg_proc.h" #include "nodes/makefuncs.h" #include "parser/parse_agg.h" #include "parser/parse_coerce.h" #include "parser/parse_expr.h" #include "parser/parse_func.h" #include "parser/parse_relation.h" #include "parser/parse_type.h" #include "utils/fmgroids.h" #include "utils/lsyscache.h" #include "utils/syscache.h" static Node *ParseComplexProjection(ParseState *pstate, char *funcname, Node *first_arg, bool *attisset); static Oid **argtype_inherit(int nargs, Oid *argtypes); static int find_inheritors(Oid relid, Oid **supervec); static CandidateList func_get_candidates(char *funcname, int nargs); static Oid **gen_cross_product(InhPaths *arginh, int nargs); static void make_arguments(ParseState *pstate, int nargs, List *fargs, Oid *input_typeids, Oid *function_typeids); static int match_argtypes(int nargs, Oid *input_typeids, CandidateList function_typeids, CandidateList *candidates); static FieldSelect *setup_field_select(Node *input, char *attname, Oid relid); static Oid *func_select_candidate(int nargs, Oid *input_typeids, CandidateList candidates); static int agg_get_candidates(char *aggname, Oid typeId, CandidateList *candidates); static Oid agg_select_candidate(Oid typeid, CandidateList candidates); /* ** ParseNestedFuncOrColumn ** Given a nested dot expression (i.e. (relation func ... attr), build up ** a tree with of Iter and Func nodes. */ Node * ParseNestedFuncOrColumn(ParseState *pstate, Attr *attr, int precedence) { List *mutator_iter; Node *retval = NULL; if (attr->paramNo != NULL) { Param *param = (Param *) transformExpr(pstate, (Node *) attr->paramNo, EXPR_RELATION_FIRST); retval = ParseFuncOrColumn(pstate, strVal(lfirst(attr->attrs)), makeList1(param), false, false, precedence); } else { Ident *ident = makeNode(Ident); ident->name = attr->relname; ident->isRel = TRUE; retval = ParseFuncOrColumn(pstate, strVal(lfirst(attr->attrs)), makeList1(ident), false, false, precedence); } /* Do more attributes follow this one? */ foreach(mutator_iter, lnext(attr->attrs)) { retval = ParseFuncOrColumn(pstate, strVal(lfirst(mutator_iter)), makeList1(retval), false, false, precedence); } return retval; } /* * parse function * * This code is confusing because the database can accept * relation.column, column.function, or relation.column.function. * In these cases, funcname is the last parameter, and fargs are * the rest. * * It can also be called as func(col) or func(col,col). * In this case, Funcname is the part before parens, and fargs * are the part in parens. * * FYI, projection is choosing column from a table. * */ Node * ParseFuncOrColumn(ParseState *pstate, char *funcname, List *fargs, bool agg_star, bool agg_distinct, int precedence) { Oid rettype = InvalidOid; Oid argrelid = InvalidOid; Oid funcid = InvalidOid; List *i = NIL; Node *first_arg = NULL; char *refname; Relation rd; int nargs = length(fargs); int argn; Func *funcnode; Oid oid_array[FUNC_MAX_ARGS]; Oid *true_oid_array; Node *retval; bool retset; bool must_be_agg = agg_star || agg_distinct; bool could_be_agg; bool attisset = false; Oid toid = InvalidOid; Expr *expr; /* * Most of the rest of the parser just assumes that functions do * not have more than FUNC_MAX_ARGS parameters. We have to test * here to protect against array overruns, etc. Of course, this * may not be a function, but the test doesn't hurt. */ if (nargs > FUNC_MAX_ARGS) elog(ERROR, "Cannot pass more than %d arguments to a function", FUNC_MAX_ARGS); if (fargs) { first_arg = lfirst(fargs); if (first_arg == NULL) elog(ERROR, "Function '%s' does not allow NULL input", funcname); } /* * test for relation.column * * check for projection methods: if function takes one argument, and * that argument is a relation, param, or PQ function returning a * complex * type, then the function could be a projection. */ /* We only have one parameter, and it's not got aggregate decoration */ if (nargs == 1 && !must_be_agg) { /* Is it a plain Relation name from the parser? */ if (IsA(first_arg, Ident) && ((Ident *) first_arg)->isRel) { Ident *ident = (Ident *) first_arg; /* First arg is a relation. This could be a projection. */ refname = ident->name; retval = qualifiedNameToVar(pstate, refname, funcname, true); if (retval) return retval; /* else drop through - attr is a set or function */ } else if (ISCOMPLEX(exprType(first_arg))) { /* * Attempt to handle projection of a complex argument. If * ParseComplexProjection can't handle the projection, we have * to keep going. */ retval = ParseComplexProjection(pstate, funcname, first_arg, &attisset); if (attisset) { toid = exprType(first_arg); rd = heap_openr_nofail(typeidTypeName(toid)); if (RelationIsValid(rd)) heap_close(rd, NoLock); else elog(ERROR, "Type '%s' is not a relation type", typeidTypeName(toid)); argrelid = typeidTypeRelid(toid); /* * A projection must match an attribute name of the rel. */ if (get_attnum(argrelid, funcname) == InvalidAttrNumber) elog(ERROR, "No such attribute or function '%s'", funcname); } if (retval) return retval; } } /* * See if it's an aggregate. */ if (must_be_agg) { /* We don't presently cope with, eg, foo(DISTINCT x,y) */ if (nargs != 1) elog(ERROR, "Aggregate functions may only have one parameter"); /* Agg's argument can't be a relation name, either */ if (IsA(first_arg, Ident) && ((Ident *) first_arg)->isRel) elog(ERROR, "Aggregate functions cannot be applied to relation names"); could_be_agg = true; } else { /* Try to parse as an aggregate if above-mentioned checks are OK */ could_be_agg = (nargs == 1) && !(IsA(first_arg, Ident) && ((Ident *) first_arg)->isRel); } if (could_be_agg) { Oid basetype = exprType(lfirst(fargs)); int ncandidates; CandidateList candidates; /* try for exact match first... */ if (SearchSysCacheExists(AGGNAME, PointerGetDatum(funcname), ObjectIdGetDatum(basetype), 0, 0)) return (Node *) ParseAgg(pstate, funcname, basetype, fargs, agg_star, agg_distinct, precedence); /* check for aggregate-that-accepts-any-type (eg, COUNT) */ if (SearchSysCacheExists(AGGNAME, PointerGetDatum(funcname), ObjectIdGetDatum(0), 0, 0)) return (Node *) ParseAgg(pstate, funcname, 0, fargs, agg_star, agg_distinct, precedence); /* * No exact match yet, so see if there is another entry in the * aggregate table that is compatible. - thomas 1998-12-05 */ ncandidates = agg_get_candidates(funcname, basetype, &candidates); if (ncandidates > 0) { Oid type; type = agg_select_candidate(basetype, candidates); if (OidIsValid(type)) { lfirst(fargs) = coerce_type(pstate, lfirst(fargs), basetype, type, -1); basetype = type; return (Node *) ParseAgg(pstate, funcname, basetype, fargs, agg_star, agg_distinct, precedence); } else { /* Multiple possible matches --- give up */ elog(ERROR, "Unable to select an aggregate function %s(%s)", funcname, typeidTypeName(basetype)); } } if (must_be_agg) { /* * No matching agg, but we had '*' or DISTINCT, so a plain * function could not have been meant. */ elog(ERROR, "There is no aggregate function %s(%s)", funcname, typeidTypeName(basetype)); } } /* * If we dropped through to here it's really a function (or a set, * which is implemented as a function). Extract arg type info and * transform relation name arguments into varnodes of the appropriate * form. */ MemSet(oid_array, 0, FUNC_MAX_ARGS * sizeof(Oid)); argn = 0; foreach(i, fargs) { Node *arg = lfirst(i); if (IsA(arg, Ident) && ((Ident *) arg)->isRel) { RangeTblEntry *rte; int vnum; Node *rteorjoin; int sublevels_up; /* * a relation */ refname = ((Ident *) arg)->name; rteorjoin = refnameRangeOrJoinEntry(pstate, refname, &sublevels_up); if (rteorjoin == NULL) rte = addImplicitRTE(pstate, refname); else if (IsA(rteorjoin, RangeTblEntry)) rte = (RangeTblEntry *) rteorjoin; else if (IsA(rteorjoin, JoinExpr)) { /* * The relation name refers to a join. We can't support * functions on join tuples (since we don't have a named * type for the join tuples), so error out. */ if (nargs == 1) { /* * We have f(x) or more likely x.f where x is a join * and f is not one of the attribute names of the join * (else we'd have recognized it above). Give an * appropriately vague error message. Would be nicer * to know which syntax was used... */ elog(ERROR, "No such attribute or function %s.%s", refname, funcname); } else { /* * There are multiple arguments, so it must be a function * call. */ elog(ERROR, "Cannot pass result of join %s to a function", refname); } rte = NULL; /* keep compiler quiet */ } else { elog(ERROR, "ParseFuncOrColumn: unexpected node type %d", nodeTag(rteorjoin)); rte = NULL; /* keep compiler quiet */ } vnum = RTERangeTablePosn(pstate, rte, &sublevels_up); /* * The parameter to be passed to the function is the whole tuple * from the relation. We build a special VarNode to reflect * this -- it has varno set to the correct range table entry, * but has varattno == 0 to signal that the whole tuple is the * argument. Also, it has typmod set to sizeof(Pointer) to * signal that the runtime representation will be a pointer * not an Oid. */ if (rte->relname == NULL) { /* * RTE is a subselect; must fail for lack of a specific type */ if (nargs == 1) { /* * Here, we probably have an unrecognized attribute of a * sub-select; again can't tell if it was x.f or f(x) */ elog(ERROR, "No such attribute or function %s.%s", refname, funcname); } else { elog(ERROR, "Cannot pass result of sub-select %s to a function", refname); } } toid = typenameTypeId(rte->relname); /* replace it in the arg list */ lfirst(i) = makeVar(vnum, InvalidAttrNumber, toid, sizeof(Pointer), sublevels_up); } else if (!attisset) toid = exprType(arg); else { /* if attisset is true, we already set toid for the single arg */ } oid_array[argn++] = toid; } /* * func_get_detail looks up the function in the catalogs, does * disambiguation for polymorphic functions, handles inheritance, and * returns the funcid and type and set or singleton status of the * function's return value. it also returns the true argument types * to the function. if func_get_detail returns true, the function * exists. otherwise, there was an error. */ if (attisset) { /* we know all of these fields already */ /* * We create a funcnode with a placeholder function seteval(). At * runtime, seteval() will execute the function identified by the * funcid it receives as parameter. * * Example: retrieve (emp.mgr.name). The plan for this will scan the * emp relation, projecting out the mgr attribute, which is a * funcid. This function is then called (via seteval()) and "name" * is projected from its result. */ funcid = F_SETEVAL; rettype = toid; retset = true; true_oid_array = oid_array; } else { bool exists; exists = func_get_detail(funcname, nargs, oid_array, &funcid, &rettype, &retset, &true_oid_array); if (!exists) { /* * If we can't find a function (or can't find a unique * function), see if this is really a type-coercion request: * single-argument function call where the function name is a * type name. If so, and if we can do the coercion trivially, * just go ahead and do it without requiring there to be a * real function for it. * * "Trivial" coercions are ones that involve binary-compatible * types and ones that are coercing a previously-unknown-type * literal constant to a specific type. * * DO NOT try to generalize this code to nontrivial coercions, * because you'll just set up an infinite recursion between * this routine and coerce_type! We have already failed to * find a suitable "real" coercion function, so we have to * fail unless this is a coercion that coerce_type can handle * by itself. Make sure this code stays in sync with what * coerce_type does! */ if (nargs == 1) { Oid targetType; targetType = GetSysCacheOid(TYPENAME, PointerGetDatum(funcname), 0, 0, 0); if (OidIsValid(targetType)) { Oid sourceType = oid_array[0]; Node *arg1 = lfirst(fargs); if ((sourceType == UNKNOWNOID && IsA(arg1, Const)) || sourceType == targetType || IS_BINARY_COMPATIBLE(sourceType, targetType)) { /* * Ah-hah, we can do it as a trivial coercion. * coerce_type can handle these cases, so why * duplicate code... */ return coerce_type(pstate, arg1, sourceType, targetType, -1); } } } /* * Oops. Time to die. * * If there is a single argument of complex type, we might be * dealing with the PostQuel notation rel.function instead of * the more usual function(rel). Give a nonspecific error * message that will cover both cases. */ if (nargs == 1) { Type tp = typeidType(oid_array[0]); if (typeTypeFlag(tp) == 'c') elog(ERROR, "No such attribute or function '%s'", funcname); ReleaseSysCache(tp); } /* Else generate a detailed complaint */ func_error(NULL, funcname, nargs, oid_array, "Unable to identify a function that satisfies the " "given argument types" "\n\tYou may need to add explicit typecasts"); } } /* got it */ funcnode = makeNode(Func); funcnode->funcid = funcid; funcnode->functype = rettype; funcnode->func_fcache = NULL; /* perform the necessary typecasting of arguments */ make_arguments(pstate, nargs, fargs, oid_array, true_oid_array); expr = makeNode(Expr); expr->typeOid = rettype; expr->opType = FUNC_EXPR; expr->oper = (Node *) funcnode; expr->args = fargs; retval = (Node *) expr; /* * For sets, we want to project out the desired attribute of the * tuples. */ if (attisset) { FieldSelect *fselect; fselect = setup_field_select(retval, funcname, argrelid); rettype = fselect->resulttype; retval = (Node *) fselect; } /* * if the function returns a set of values, then we need to iterate * over all the returned values in the executor, so we stick an iter * node here. if it returns a singleton, then we don't need the iter * node. */ if (retset) { Iter *iter = makeNode(Iter); iter->itertype = rettype; iter->iterexpr = retval; retval = (Node *) iter; } return retval; } static int agg_get_candidates(char *aggname, Oid typeId, CandidateList *candidates) { CandidateList current_candidate; Relation pg_aggregate_desc; HeapScanDesc pg_aggregate_scan; HeapTuple tup; Form_pg_aggregate agg; int ncandidates = 0; ScanKeyData aggKey[1]; *candidates = NULL; ScanKeyEntryInitialize(&aggKey[0], 0, Anum_pg_aggregate_aggname, F_NAMEEQ, NameGetDatum(aggname)); pg_aggregate_desc = heap_openr(AggregateRelationName, AccessShareLock); pg_aggregate_scan = heap_beginscan(pg_aggregate_desc, 0, SnapshotSelf, /* ??? */ 1, aggKey); while (HeapTupleIsValid(tup = heap_getnext(pg_aggregate_scan, 0))) { agg = (Form_pg_aggregate) GETSTRUCT(tup); current_candidate = (CandidateList) palloc(sizeof(struct _CandidateList)); current_candidate->args = (Oid *) palloc(sizeof(Oid)); current_candidate->args[0] = agg->aggbasetype; current_candidate->next = *candidates; *candidates = current_candidate; ncandidates++; } heap_endscan(pg_aggregate_scan); heap_close(pg_aggregate_desc, AccessShareLock); return ncandidates; } /* agg_get_candidates() */ /* agg_select_candidate() * * Try to choose only one candidate aggregate function from a list of * possible matches. Return value is Oid of input type of aggregate * if successful, else InvalidOid. */ static Oid agg_select_candidate(Oid typeid, CandidateList candidates) { CandidateList current_candidate; CandidateList last_candidate; Oid current_typeid; int ncandidates; CATEGORY category, current_category; /* * First look for exact matches or binary compatible matches. (Of * course exact matches shouldn't even get here, but anyway.) */ ncandidates = 0; last_candidate = NULL; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeid = current_candidate->args[0]; if (current_typeid == typeid || IS_BINARY_COMPATIBLE(current_typeid, typeid)) { last_candidate = current_candidate; ncandidates++; } } if (ncandidates == 1) return last_candidate->args[0]; /* * If no luck that way, look for candidates which allow coercion and * have a preferred type. Keep all candidates if none match. */ category = TypeCategory(typeid); ncandidates = 0; last_candidate = NULL; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeid = current_candidate->args[0]; current_category = TypeCategory(current_typeid); if (current_category == category && IsPreferredType(current_category, current_typeid) && can_coerce_type(1, &typeid, ¤t_typeid)) { /* only one so far? then keep it... */ if (last_candidate == NULL) { candidates = current_candidate; last_candidate = current_candidate; ncandidates = 1; } /* otherwise, keep this one too... */ else { last_candidate->next = current_candidate; last_candidate = current_candidate; ncandidates++; } } /* otherwise, don't bother keeping this one around... */ } if (last_candidate) /* terminate rebuilt list */ last_candidate->next = NULL; if (ncandidates == 1) return candidates->args[0]; return InvalidOid; } /* agg_select_candidate() */ /* func_get_candidates() * get a list of all argument type vectors for which a function named * funcname taking nargs arguments exists */ static CandidateList func_get_candidates(char *funcname, int nargs) { Relation heapRelation; Relation idesc; ScanKeyData skey; HeapTupleData tuple; IndexScanDesc sd; RetrieveIndexResult indexRes; Form_pg_proc pgProcP; CandidateList candidates = NULL; CandidateList current_candidate; int i; heapRelation = heap_openr(ProcedureRelationName, AccessShareLock); ScanKeyEntryInitialize(&skey, (bits16) 0x0, (AttrNumber) Anum_pg_proc_proname, (RegProcedure) F_NAMEEQ, (Datum) funcname); idesc = index_openr(ProcedureNameIndex); sd = index_beginscan(idesc, false, 1, &skey); do { indexRes = index_getnext(sd, ForwardScanDirection); if (indexRes) { Buffer buffer; tuple.t_datamcxt = NULL; tuple.t_data = NULL; tuple.t_self = indexRes->heap_iptr; heap_fetch(heapRelation, SnapshotNow, &tuple, &buffer); pfree(indexRes); if (tuple.t_data != NULL) { pgProcP = (Form_pg_proc) GETSTRUCT(&tuple); if (pgProcP->pronargs == nargs) { current_candidate = (CandidateList) palloc(sizeof(struct _CandidateList)); current_candidate->args = (Oid *) palloc(FUNC_MAX_ARGS * sizeof(Oid)); MemSet(current_candidate->args, 0, FUNC_MAX_ARGS * sizeof(Oid)); for (i = 0; i < nargs; i++) current_candidate->args[i] = pgProcP->proargtypes[i]; current_candidate->next = candidates; candidates = current_candidate; } ReleaseBuffer(buffer); } } } while (indexRes); index_endscan(sd); index_close(idesc); heap_close(heapRelation, AccessShareLock); return candidates; } /* match_argtypes() * Given a list of possible typeid arrays to a function and an array of * input typeids, produce a shortlist of those function typeid arrays * that match the input typeids (either exactly or by coercion), and * return the number of such arrays */ static int match_argtypes(int nargs, Oid *input_typeids, CandidateList function_typeids, CandidateList *candidates) /* return value */ { CandidateList current_candidate; CandidateList matching_candidate; Oid *current_typeids; int ncandidates = 0; *candidates = NULL; for (current_candidate = function_typeids; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeids = current_candidate->args; if (can_coerce_type(nargs, input_typeids, current_typeids)) { matching_candidate = (CandidateList) palloc(sizeof(struct _CandidateList)); matching_candidate->args = current_typeids; matching_candidate->next = *candidates; *candidates = matching_candidate; ncandidates++; } } return ncandidates; } /* match_argtypes() */ /* func_select_candidate() * Given the input argtype array and more than one candidate * for the function argtype array, attempt to resolve the conflict. * Returns the selected argtype array if the conflict can be resolved, * otherwise returns NULL. * * By design, this is pretty similar to oper_select_candidate in parse_oper.c. * However, the calling convention is a little different: we assume the caller * already pruned away "candidates" that aren't actually coercion-compatible * with the input types, whereas oper_select_candidate must do that itself. */ static Oid * func_select_candidate(int nargs, Oid *input_typeids, CandidateList candidates) { CandidateList current_candidate; CandidateList last_candidate; Oid *current_typeids; Oid current_type; int i; int ncandidates; int nbestMatch, nmatch; CATEGORY slot_category[FUNC_MAX_ARGS], current_category; bool slot_has_preferred_type[FUNC_MAX_ARGS]; bool resolved_unknowns; /* * Run through all candidates and keep those with the most matches on * exact types. Keep all candidates if none match. */ ncandidates = 0; nbestMatch = 0; last_candidate = NULL; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeids = current_candidate->args; nmatch = 0; for (i = 0; i < nargs; i++) { if (input_typeids[i] != UNKNOWNOID && current_typeids[i] == input_typeids[i]) nmatch++; } /* take this one as the best choice so far? */ if ((nmatch > nbestMatch) || (last_candidate == NULL)) { nbestMatch = nmatch; candidates = current_candidate; last_candidate = current_candidate; ncandidates = 1; } /* no worse than the last choice, so keep this one too? */ else if (nmatch == nbestMatch) { last_candidate->next = current_candidate; last_candidate = current_candidate; ncandidates++; } /* otherwise, don't bother keeping this one... */ } if (last_candidate) /* terminate rebuilt list */ last_candidate->next = NULL; if (ncandidates == 1) return candidates->args; /* * Still too many candidates? Run through all candidates and keep * those with the most matches on exact types + binary-compatible * types. Keep all candidates if none match. */ ncandidates = 0; nbestMatch = 0; last_candidate = NULL; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeids = current_candidate->args; nmatch = 0; for (i = 0; i < nargs; i++) { if (input_typeids[i] != UNKNOWNOID) { if (current_typeids[i] == input_typeids[i] || IS_BINARY_COMPATIBLE(current_typeids[i], input_typeids[i])) nmatch++; } } /* take this one as the best choice so far? */ if ((nmatch > nbestMatch) || (last_candidate == NULL)) { nbestMatch = nmatch; candidates = current_candidate; last_candidate = current_candidate; ncandidates = 1; } /* no worse than the last choice, so keep this one too? */ else if (nmatch == nbestMatch) { last_candidate->next = current_candidate; last_candidate = current_candidate; ncandidates++; } /* otherwise, don't bother keeping this one... */ } if (last_candidate) /* terminate rebuilt list */ last_candidate->next = NULL; if (ncandidates == 1) return candidates->args; /* * Still too many candidates? Now look for candidates which are * preferred types at the args that will require coercion. Keep all * candidates if none match. */ ncandidates = 0; nbestMatch = 0; last_candidate = NULL; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeids = current_candidate->args; nmatch = 0; for (i = 0; i < nargs; i++) { if (input_typeids[i] != UNKNOWNOID) { current_category = TypeCategory(current_typeids[i]); if (current_typeids[i] == input_typeids[i] || IsPreferredType(current_category, current_typeids[i])) nmatch++; } } if ((nmatch > nbestMatch) || (last_candidate == NULL)) { nbestMatch = nmatch; candidates = current_candidate; last_candidate = current_candidate; ncandidates = 1; } else if (nmatch == nbestMatch) { last_candidate->next = current_candidate; last_candidate = current_candidate; ncandidates++; } } if (last_candidate) /* terminate rebuilt list */ last_candidate->next = NULL; if (ncandidates == 1) return candidates->args; /* * Still too many candidates? Try assigning types for the unknown * columns. * * We do this by examining each unknown argument position to see if we * can determine a "type category" for it. If any candidate has an * input datatype of STRING category, use STRING category (this bias * towards STRING is appropriate since unknown-type literals look like * strings). Otherwise, if all the candidates agree on the type * category of this argument position, use that category. Otherwise, * fail because we cannot determine a category. * * If we are able to determine a type category, also notice whether any * of the candidates takes a preferred datatype within the category. * * Having completed this examination, remove candidates that accept the * wrong category at any unknown position. Also, if at least one * candidate accepted a preferred type at a position, remove * candidates that accept non-preferred types. * * If we are down to one candidate at the end, we win. */ resolved_unknowns = false; for (i = 0; i < nargs; i++) { bool have_conflict; if (input_typeids[i] != UNKNOWNOID) continue; resolved_unknowns = true; /* assume we can do it */ slot_category[i] = INVALID_TYPE; slot_has_preferred_type[i] = false; have_conflict = false; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { current_typeids = current_candidate->args; current_type = current_typeids[i]; current_category = TypeCategory(current_type); if (slot_category[i] == INVALID_TYPE) { /* first candidate */ slot_category[i] = current_category; slot_has_preferred_type[i] = IsPreferredType(current_category, current_type); } else if (current_category == slot_category[i]) { /* more candidates in same category */ slot_has_preferred_type[i] |= IsPreferredType(current_category, current_type); } else { /* category conflict! */ if (current_category == STRING_TYPE) { /* STRING always wins if available */ slot_category[i] = current_category; slot_has_preferred_type[i] = IsPreferredType(current_category, current_type); } else { /* * Remember conflict, but keep going (might find * STRING) */ have_conflict = true; } } } if (have_conflict && slot_category[i] != STRING_TYPE) { /* Failed to resolve category conflict at this position */ resolved_unknowns = false; break; } } if (resolved_unknowns) { /* Strip non-matching candidates */ ncandidates = 0; last_candidate = NULL; for (current_candidate = candidates; current_candidate != NULL; current_candidate = current_candidate->next) { bool keepit = true; current_typeids = current_candidate->args; for (i = 0; i < nargs; i++) { if (input_typeids[i] != UNKNOWNOID) continue; current_type = current_typeids[i]; current_category = TypeCategory(current_type); if (current_category != slot_category[i]) { keepit = false; break; } if (slot_has_preferred_type[i] && !IsPreferredType(current_category, current_type)) { keepit = false; break; } } if (keepit) { /* keep this candidate */ last_candidate = current_candidate; ncandidates++; } else { /* forget this candidate */ if (last_candidate) last_candidate->next = current_candidate->next; else candidates = current_candidate->next; } } if (last_candidate) /* terminate rebuilt list */ last_candidate->next = NULL; } if (ncandidates == 1) return candidates->args; return NULL; /* failed to determine a unique candidate */ } /* func_select_candidate() */ /* func_get_detail() * Find the named function in the system catalogs. * * Attempt to find the named function in the system catalogs with * arguments exactly as specified, so that the normal case * (exact match) is as quick as possible. * * If an exact match isn't found: * 1) get a vector of all possible input arg type arrays constructed * from the superclasses of the original input arg types * 2) get a list of all possible argument type arrays to the function * with given name and number of arguments * 3) for each input arg type array from vector #1: * a) find how many of the function arg type arrays from list #2 * it can be coerced to * b) if the answer is one, we have our function * c) if the answer is more than one, attempt to resolve the conflict * d) if the answer is zero, try the next array from vector #1 */ bool func_get_detail(char *funcname, int nargs, Oid *argtypes, Oid *funcid, /* return value */ Oid *rettype, /* return value */ bool *retset, /* return value */ Oid **true_typeids) /* return value */ { HeapTuple ftup; /* attempt to find with arguments exactly as specified... */ ftup = SearchSysCache(PROCNAME, PointerGetDatum(funcname), Int32GetDatum(nargs), PointerGetDatum(argtypes), 0); if (HeapTupleIsValid(ftup)) { /* given argument types are the right ones */ *true_typeids = argtypes; } else { /* * didn't find an exact match, so now try to match up * candidates... */ CandidateList function_typeids; function_typeids = func_get_candidates(funcname, nargs); /* found something, so let's look through them... */ if (function_typeids != NULL) { Oid **input_typeid_vector = NULL; Oid *current_input_typeids; /* * First we will search with the given argtypes, then with * variants based on replacing complex types with their * inheritance ancestors. Stop as soon as any match is found. */ current_input_typeids = argtypes; do { CandidateList current_function_typeids; int ncandidates; ncandidates = match_argtypes(nargs, current_input_typeids, function_typeids, ¤t_function_typeids); /* one match only? then run with it... */ if (ncandidates == 1) { *true_typeids = current_function_typeids->args; ftup = SearchSysCache(PROCNAME, PointerGetDatum(funcname), Int32GetDatum(nargs), PointerGetDatum(*true_typeids), 0); Assert(HeapTupleIsValid(ftup)); break; } /* * multiple candidates? then better decide or throw an * error... */ if (ncandidates > 1) { *true_typeids = func_select_candidate(nargs, current_input_typeids, current_function_typeids); if (*true_typeids != NULL) { /* was able to choose a best candidate */ ftup = SearchSysCache(PROCNAME, PointerGetDatum(funcname), Int32GetDatum(nargs), PointerGetDatum(*true_typeids), 0); Assert(HeapTupleIsValid(ftup)); break; } /* * otherwise, ambiguous function call, so fail by * exiting loop with ftup still NULL. */ break; } /* * No match here, so try the next inherited type vector. * First time through, we need to compute the list of * vectors. */ if (input_typeid_vector == NULL) input_typeid_vector = argtype_inherit(nargs, argtypes); current_input_typeids = *input_typeid_vector++; } while (current_input_typeids != NULL); } } if (HeapTupleIsValid(ftup)) { Form_pg_proc pform = (Form_pg_proc) GETSTRUCT(ftup); *funcid = ftup->t_data->t_oid; *rettype = pform->prorettype; *retset = pform->proretset; ReleaseSysCache(ftup); return true; } return false; } /* func_get_detail() */ /* * argtype_inherit() -- Construct an argtype vector reflecting the * inheritance properties of the supplied argv. * * This function is used to disambiguate among functions with the * same name but different signatures. It takes an array of input * type ids. For each type id in the array that's a complex type * (a class), it walks up the inheritance tree, finding all * superclasses of that type. A vector of new Oid type arrays * is returned to the caller, reflecting the structure of the * inheritance tree above the supplied arguments. * * The order of this vector is as follows: all superclasses of the * rightmost complex class are explored first. The exploration * continues from right to left. This policy means that we favor * keeping the leftmost argument type as low in the inheritance tree * as possible. This is intentional; it is exactly what we need to * do for method dispatch. The last type array we return is all * zeroes. This will match any functions for which return types are * not defined. There are lots of these (mostly builtins) in the * catalogs. */ static Oid ** argtype_inherit(int nargs, Oid *argtypes) { Oid relid; int i; InhPaths arginh[FUNC_MAX_ARGS]; for (i = 0; i < FUNC_MAX_ARGS; i++) { if (i < nargs) { arginh[i].self = argtypes[i]; if ((relid = typeidTypeRelid(argtypes[i])) != InvalidOid) arginh[i].nsupers = find_inheritors(relid, &(arginh[i].supervec)); else { arginh[i].nsupers = 0; arginh[i].supervec = (Oid *) NULL; } } else { arginh[i].self = InvalidOid; arginh[i].nsupers = 0; arginh[i].supervec = (Oid *) NULL; } } /* return an ordered cross-product of the classes involved */ return gen_cross_product(arginh, nargs); } static int find_inheritors(Oid relid, Oid **supervec) { Relation inhrel; HeapScanDesc inhscan; ScanKeyData skey; HeapTuple inhtup; Oid *relidvec; int nvisited; List *visited, *queue; List *elt; bool newrelid; nvisited = 0; queue = NIL; visited = NIL; inhrel = heap_openr(InheritsRelationName, AccessShareLock); /* * Use queue to do a breadth-first traversal of the inheritance graph * from the relid supplied up to the root. At the top of the loop, * relid is the OID of the reltype to check next, queue is the list of * pending rels to check after this one, and visited is the list of * relids we need to output. */ do { /* find all types this relid inherits from, and add them to queue */ ScanKeyEntryInitialize(&skey, 0x0, Anum_pg_inherits_inhrelid, F_OIDEQ, ObjectIdGetDatum(relid)); inhscan = heap_beginscan(inhrel, 0, SnapshotNow, 1, &skey); while (HeapTupleIsValid(inhtup = heap_getnext(inhscan, 0))) { Form_pg_inherits inh = (Form_pg_inherits) GETSTRUCT(inhtup); queue = lappendi(queue, inh->inhparent); } heap_endscan(inhscan); /* pull next unvisited relid off the queue */ newrelid = false; while (queue != NIL) { relid = lfirsti(queue); queue = lnext(queue); if (!intMember(relid, visited)) { newrelid = true; break; } } if (newrelid) { visited = lappendi(visited, relid); nvisited++; } } while (newrelid); heap_close(inhrel, AccessShareLock); if (nvisited > 0) { relidvec = (Oid *) palloc(nvisited * sizeof(Oid)); *supervec = relidvec; foreach(elt, visited) { /* return the type id, rather than the relation id */ Relation rd; Oid trelid; relid = lfirsti(elt); rd = heap_open(relid, NoLock); trelid = typenameTypeId(RelationGetRelationName(rd)); heap_close(rd, NoLock); *relidvec++ = trelid; } } else *supervec = (Oid *) NULL; freeList(visited); /* * there doesn't seem to be any equally easy way to release the queue * list cells, but since they're palloc'd space it's not critical. */ return nvisited; } static Oid ** gen_cross_product(InhPaths *arginh, int nargs) { int nanswers; Oid **result, **iter; Oid *oneres; int i, j; int cur[FUNC_MAX_ARGS]; nanswers = 1; for (i = 0; i < nargs; i++) { nanswers *= (arginh[i].nsupers + 2); cur[i] = 0; } iter = result = (Oid **) palloc(sizeof(Oid *) * nanswers); /* compute the cross product from right to left */ for (;;) { oneres = (Oid *) palloc(FUNC_MAX_ARGS * sizeof(Oid)); MemSet(oneres, 0, FUNC_MAX_ARGS * sizeof(Oid)); for (i = nargs - 1; i >= 0 && cur[i] > arginh[i].nsupers; i--) continue; /* if we're done, terminate with NULL pointer */ if (i < 0) { *iter = NULL; return result; } /* no, increment this column and zero the ones after it */ cur[i] = cur[i] + 1; for (j = nargs - 1; j > i; j--) cur[j] = 0; for (i = 0; i < nargs; i++) { if (cur[i] == 0) oneres[i] = arginh[i].self; else if (cur[i] > arginh[i].nsupers) oneres[i] = 0; /* wild card */ else oneres[i] = arginh[i].supervec[cur[i] - 1]; } *iter++ = oneres; } } /* * Given two type OIDs, determine whether the first is a complex type * (class type) that inherits from the second. */ bool typeInheritsFrom(Oid subclassTypeId, Oid superclassTypeId) { Oid relid; Oid *supervec; int nsupers, i; bool result; if (!ISCOMPLEX(subclassTypeId) || !ISCOMPLEX(superclassTypeId)) return false; relid = typeidTypeRelid(subclassTypeId); if (relid == InvalidOid) return false; nsupers = find_inheritors(relid, &supervec); result = false; for (i = 0; i < nsupers; i++) { if (supervec[i] == superclassTypeId) { result = true; break; } } if (supervec) pfree(supervec); return result; } /* make_arguments() * Given the number and types of arguments to a function, and the * actual arguments and argument types, do the necessary typecasting. */ static void make_arguments(ParseState *pstate, int nargs, List *fargs, Oid *input_typeids, Oid *function_typeids) { List *current_fargs; int i; for (i = 0, current_fargs = fargs; i < nargs; i++, current_fargs = lnext(current_fargs)) { /* types don't match? then force coercion using a function call... */ if (input_typeids[i] != function_typeids[i]) { lfirst(current_fargs) = coerce_type(pstate, lfirst(current_fargs), input_typeids[i], function_typeids[i], -1); } } } /* ** setup_field_select ** Build a FieldSelect node that says which attribute to project to. ** This routine is called by ParseFuncOrColumn() when we have found ** a projection on a function result or parameter. */ static FieldSelect * setup_field_select(Node *input, char *attname, Oid relid) { FieldSelect *fselect = makeNode(FieldSelect); AttrNumber attno; attno = get_attnum(relid, attname); fselect->arg = input; fselect->fieldnum = attno; fselect->resulttype = get_atttype(relid, attno); fselect->resulttypmod = get_atttypmod(relid, attno); return fselect; } /* * ParseComplexProjection - * handles function calls with a single argument that is of complex type. * This routine returns NULL if it can't handle the projection (eg. sets). */ static Node * ParseComplexProjection(ParseState *pstate, char *funcname, Node *first_arg, bool *attisset) { Oid argtype; Oid argrelid; FieldSelect *fselect; switch (nodeTag(first_arg)) { case T_Iter: { Iter *iter = (Iter *) first_arg; /* * If the argument of the Iter returns a tuple, funcname * may be a projection. If so, we stick the FieldSelect * *inside* the Iter --- this is klugy, but necessary * because ExecTargetList() currently does the right thing * only when the Iter node is at the top level of a * targetlist item. */ argtype = iter->itertype; argrelid = typeidTypeRelid(argtype); if (argrelid && get_attnum(argrelid, funcname) != InvalidAttrNumber) { fselect = setup_field_select(iter->iterexpr, funcname, argrelid); iter->iterexpr = (Node *) fselect; iter->itertype = fselect->resulttype; return (Node *) iter; } break; } case T_Var: { /* * The argument is a set, so this is either a projection * or a function call on this set. */ *attisset = true; break; } case T_Expr: { Expr *expr = (Expr *) first_arg; Func *funcnode; if (expr->opType != FUNC_EXPR) break; /* * If the argument is a function returning a tuple, * funcname may be a projection */ funcnode = (Func *) expr->oper; argtype = funcnode->functype; argrelid = typeidTypeRelid(argtype); if (argrelid && get_attnum(argrelid, funcname) != InvalidAttrNumber) { fselect = setup_field_select((Node *) expr, funcname, argrelid); return (Node *) fselect; } break; } case T_Param: { Param *param = (Param *) first_arg; /* * If the Param is a complex type, this could be a * projection */ argtype = param->paramtype; argrelid = typeidTypeRelid(argtype); if (argrelid && get_attnum(argrelid, funcname) != InvalidAttrNumber) { fselect = setup_field_select((Node *) param, funcname, argrelid); return (Node *) fselect; } break; } default: break; } return NULL; } /* * Error message when function lookup fails that gives details of the * argument types */ void func_error(char *caller, char *funcname, int nargs, Oid *argtypes, char *msg) { char p[(NAMEDATALEN + 2) * FUNC_MAX_ARGS], *ptr; int i; ptr = p; *ptr = '\0'; for (i = 0; i < nargs; i++) { if (i) { *ptr++ = ','; *ptr++ = ' '; } if (argtypes[i] != 0) { strcpy(ptr, typeidTypeName(argtypes[i])); *(ptr + NAMEDATALEN) = '\0'; } else strcpy(ptr, "opaque"); ptr += strlen(ptr); } if (caller == NULL) { elog(ERROR, "Function '%s(%s)' does not exist%s%s", funcname, p, ((msg != NULL) ? "\n\t" : ""), ((msg != NULL) ? msg : "")); } else { elog(ERROR, "%s: function '%s(%s)' does not exist%s%s", caller, funcname, p, ((msg != NULL) ? "\n\t" : ""), ((msg != NULL) ? msg : "")); } }