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postgres/src/backend/parser/parse_func.c
Tom Lane 7d6af50f43 Make algorithm for resolving UNKNOWN function/operator inputs be 
insensitive to the order of arguments.  Per pghackers discussion 12/10/00.
2000-12-15 19:22:03 +00:00

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/*-------------------------------------------------------------------------
*
* parse_func.c
* handle function calls in parser
*
* Portions Copyright (c) 1996-2000, PostgreSQL, Inc
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_func.c,v 1.95 2000/12/15 19:22:03 tgl 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;
}
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, &current_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() */
/*
* parse function
*/
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);
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;
if (fargs)
{
first_arg = lfirst(fargs);
if (first_arg == NULL)
elog(ERROR, "Function '%s' does not allow NULL input", funcname);
}
/*
* 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, "Functions on sets are not yet supported");
}
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));
nargs = 0;
foreach(i, fargs)
{
Node *arg = lfirst(i);
if (IsA(arg, Ident) && ((Ident *) arg)->isRel)
{
RangeTblEntry *rte;
int vnum;
int sublevels_up;
/*
* a relation
*/
refname = ((Ident *) arg)->name;
rte = refnameRangeTableEntry(pstate, refname);
if (rte == NULL)
rte = addImplicitRTE(pstate, refname);
vnum = RTERangeTablePosn(pstate, rte, &sublevels_up);
/*
* for func(relname), the param to the function is the tuple
* under consideration. 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.
*/
if (rte->relname == NULL)
elog(ERROR,
"function applied to tuple is not supported for subSELECTs");
toid = typenameTypeId(rte->relname);
/* replace it in the arg list */
lfirst(i) = makeVar(vnum, 0, toid, -1, sublevels_up);
}
else if (!attisset)
toid = exprType(arg);
else
{
/* if attisset is true, we already set toid for the single arg */
}
/*
* 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.
*/
if (nargs >= FUNC_MAX_ARGS)
elog(ERROR, "Cannot pass more than %d arguments to a function",
FUNC_MAX_ARGS);
oid_array[nargs++] = 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;
}
/* 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,
&current_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);
/* XXX Is there still a reason for this restriction? */
if (attno < 0)
elog(ERROR, "Cannot reference attribute '%s'"
" of tuple params/return values for functions", 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 : ""));
}
}
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