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postgres/src/backend/parser/parse_oper.c
Tom Lane 5adebf83b6 Clean up some bugs in oper_select_candidate(), notably the 
last loop which would return the *first* surviving-to-that-point candidate
regardless of which one actually passed the test.  This was producing
such curious results as 'oid % 2' getting translated to 'int2(oid) % 2'.
1999-08-26 04:59:15 +00:00

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/*-------------------------------------------------------------------------
*
* parse_oper.h
* handle operator things for parser
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.31 1999/08/26 04:59:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/pg_operator.h"
#include "parser/parse_coerce.h"
#include "parser/parse_func.h"
#include "parser/parse_oper.h"
#include "parser/parse_type.h"
#include "utils/syscache.h"
static Oid *oper_select_candidate(int nargs, Oid *input_typeids,
CandidateList candidates);
static Operator oper_exact(char *op, Oid arg1, Oid arg2);
static Operator oper_inexact(char *op, Oid arg1, Oid arg2);
static int binary_oper_get_candidates(char *opname,
CandidateList *candidates);
static int unary_oper_get_candidates(char *op,
Oid typeId,
CandidateList *candidates,
char rightleft);
static void op_error(char *op, Oid arg1, Oid arg2);
Oid
any_ordering_op(int restype)
{
Operator order_op;
Oid order_opid;
order_op = oper("<", restype, restype, TRUE);
if (!HeapTupleIsValid(order_op))
{
elog(ERROR, "Unable to identify an ordering operator '%s' for type '%s'"
"\n\tUse an explicit ordering operator or modify the query",
"<", typeidTypeName(restype));
}
order_opid = oprid(order_op);
return order_opid;
}
/* given operator, return the operator OID */
Oid
oprid(Operator op)
{
return op->t_data->t_oid;
}
/* binary_oper_get_candidates()
* given opname, find all possible input type pairs for which an operator
* named opname exists. Build a list of the candidate input types.
* Returns number of candidates found.
*/
static int
binary_oper_get_candidates(char *opname,
CandidateList *candidates)
{
CandidateList current_candidate;
Relation pg_operator_desc;
HeapScanDesc pg_operator_scan;
HeapTuple tup;
Form_pg_operator oper;
int nkeys;
int ncandidates = 0;
ScanKeyData opKey[3];
*candidates = NULL;
ScanKeyEntryInitialize(&opKey[0], 0,
Anum_pg_operator_oprname,
F_NAMEEQ,
NameGetDatum(opname));
ScanKeyEntryInitialize(&opKey[1], 0,
Anum_pg_operator_oprkind,
F_CHAREQ,
CharGetDatum('b'));
nkeys = 2;
pg_operator_desc = heap_openr(OperatorRelationName);
pg_operator_scan = heap_beginscan(pg_operator_desc,
0,
SnapshotSelf, /* ??? */
nkeys,
opKey);
while (HeapTupleIsValid(tup = heap_getnext(pg_operator_scan, 0)))
{
current_candidate = (CandidateList) palloc(sizeof(struct _CandidateList));
current_candidate->args = (Oid *) palloc(2 * sizeof(Oid));
oper = (Form_pg_operator) GETSTRUCT(tup);
current_candidate->args[0] = oper->oprleft;
current_candidate->args[1] = oper->oprright;
current_candidate->next = *candidates;
*candidates = current_candidate;
ncandidates++;
}
heap_endscan(pg_operator_scan);
heap_close(pg_operator_desc);
return ncandidates;
} /* binary_oper_get_candidates() */
/* oper_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.
*
* This routine is new code, replacing binary_oper_select_candidate()
* which dates from v4.2/v1.0.x days. It tries very hard to match up
* operators with types, including allowing type coersions if necessary.
* The important thing is that the code do as much as possible,
* while _never_ doing the wrong thing, where "the wrong thing" would
* be returning an operator when other better choices are available,
* or returning an operator which is a non-intuitive possibility.
* - thomas 1998-05-21
*
* The comments below came from binary_oper_select_candidate(), and
* illustrate the issues and choices which are possible:
* - thomas 1998-05-20
*
* current wisdom holds that the default operator should be one in which
* both operands have the same type (there will only be one such
* operator)
*
* 7.27.93 - I have decided not to do this; it's too hard to justify, and
* it's easy enough to typecast explicitly - avi
* [the rest of this routine was commented out since then - ay]
*
* 6/23/95 - I don't complete agree with avi. In particular, casting
* floats is a pain for users. Whatever the rationale behind not doing
* this is, I need the following special case to work.
*
* In the WHERE clause of a query, if a float is specified without
* quotes, we treat it as float8. I added the float48* operators so
* that we can operate on float4 and float8. But now we have more than
* one matching operator if the right arg is unknown (eg. float
* specified with quotes). This break some stuff in the regression
* test where there are floats in quotes not properly casted. Below is
* the solution. In addition to requiring the operator operates on the
* same type for both operands [as in the code Avi originally
* commented out], we also require that the operators be equivalent in
* some sense. (see equivalentOpersAfterPromotion for details.)
* - ay 6/95
*/
static Oid *
oper_select_candidate(int nargs,
Oid *input_typeids,
CandidateList candidates)
{
CandidateList current_candidate;
CandidateList last_candidate;
Oid *current_typeids;
int unknownOids;
int i;
int ncandidates;
int nbestMatch,
nmatch;
CATEGORY slot_category,
current_category;
Oid slot_type,
current_type;
/*
* Run through all candidates and keep those with the most matches
* on explicit 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)
{
if (ncandidates > 0 &&
(!can_coerce_type(1, &input_typeids[0], &candidates->args[0]) ||
(nargs > 1 &&
!can_coerce_type(1, &input_typeids[1], &candidates->args[1]))))
ncandidates = 0;
return (ncandidates == 1) ? candidates->args : NULL;
}
/*
* Still too many candidates?
* Now look for candidates which allow coersion and are preferred 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_category = TypeCategory(current_typeids[i]);
if (current_typeids[i] == input_typeids[i])
nmatch++;
else if (IsPreferredType(current_category, current_typeids[i])
&& can_coerce_type(1, &input_typeids[i], &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)
{
if (ncandidates > 0 &&
(!can_coerce_type(1, &input_typeids[0], &candidates->args[0]) ||
(nargs > 1 &&
!can_coerce_type(1, &input_typeids[1], &candidates->args[1]))))
ncandidates = 0;
return (ncandidates == 1) ? candidates->args : NULL;
}
/*
* Still too many candidates?
* Try assigning types for the unknown columns.
*/
unknownOids = FALSE;
current_type = UNKNOWNOID;
for (i = 0; i < nargs; i++)
{
if ((input_typeids[i] != UNKNOWNOID)
&& (input_typeids[i] != InvalidOid))
current_type = input_typeids[i];
else
unknownOids = TRUE;
}
if (unknownOids && (current_type != UNKNOWNOID))
{
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 (current_type == current_typeids[i] ||
IS_BINARY_COMPATIBLE(current_type, current_typeids[i]))
nmatch++;
}
if (nmatch == nargs)
return candidates->args;
}
}
for (i = 0; i < nargs; i++)
{
if (input_typeids[i] == UNKNOWNOID)
{
slot_category = INVALID_TYPE;
slot_type = InvalidOid;
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_typeids[i]);
if (slot_category == InvalidOid)
{
slot_category = current_category;
slot_type = current_type;
}
else if (current_category != slot_category)
return NULL;
else if (current_type != slot_type)
{
if (IsPreferredType(slot_category, current_type))
{
slot_type = current_type;
candidates = current_candidate;
}
else
{
}
}
}
if (slot_type != InvalidOid)
input_typeids[i] = slot_type;
}
else
{
}
}
ncandidates = 0;
last_candidate = NULL;
for (current_candidate = candidates;
current_candidate != NULL;
current_candidate = current_candidate->next)
{
if (can_coerce_type(1, &input_typeids[0], &current_candidate->args[0])
&& can_coerce_type(1, &input_typeids[1], &current_candidate->args[1]))
{
ncandidates++;
last_candidate = current_candidate;
}
}
return (ncandidates == 1) ? last_candidate->args : NULL;
} /* oper_select_candidate() */
/* oper_exact()
* Given operator, and arguments, return oper struct or NULL.
* Inputs:
* arg1, arg2: Type IDs
*/
static Operator
oper_exact(char *op, Oid arg1, Oid arg2)
{
HeapTuple tup;
/* Unspecified type for one of the arguments? then use the other */
if ((arg1 == UNKNOWNOID) && (arg2 != InvalidOid))
arg1 = arg2;
else if ((arg2 == UNKNOWNOID) && (arg1 != InvalidOid))
arg2 = arg1;
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(arg1),
ObjectIdGetDatum(arg2),
CharGetDatum('b'));
return (Operator) tup;
} /* oper_exact() */
/* oper_inexact()
* Given operator, types of arg1, and arg2, return oper struct or NULL.
* Inputs:
* arg1, arg2: Type IDs
*/
static Operator
oper_inexact(char *op, Oid arg1, Oid arg2)
{
HeapTuple tup;
CandidateList candidates;
int ncandidates;
Oid *targetOids;
Oid inputOids[2];
/* Unspecified type for one of the arguments? then use the other */
if (arg2 == InvalidOid)
arg2 = arg1;
if (arg1 == InvalidOid)
arg1 = arg2;
ncandidates = binary_oper_get_candidates(op, &candidates);
/* No operators found? Then return null... */
if (ncandidates == 0)
return NULL;
/* Or found exactly one? Then proceed... */
else if (ncandidates == 1)
{
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(candidates->args[0]),
ObjectIdGetDatum(candidates->args[1]),
CharGetDatum('b'));
Assert(HeapTupleIsValid(tup));
}
/* Otherwise, multiple operators of the desired types found... */
else
{
inputOids[0] = arg1;
inputOids[1] = arg2;
targetOids = oper_select_candidate(2, inputOids, candidates);
if (targetOids != NULL)
{
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(targetOids[0]),
ObjectIdGetDatum(targetOids[1]),
CharGetDatum('b'));
}
else
tup = NULL;
}
return (Operator) tup;
} /* oper_inexact() */
/* oper()
* Given operator, types of arg1, and arg2, return oper struct.
* Inputs:
* arg1, arg2: Type IDs
*/
Operator
oper(char *opname, Oid ltypeId, Oid rtypeId, bool noWarnings)
{
HeapTuple tup;
/* check for exact match on this operator... */
if (HeapTupleIsValid(tup = oper_exact(opname, ltypeId, rtypeId)))
{
}
/* try to find a match on likely candidates... */
else if (HeapTupleIsValid(tup = oper_inexact(opname, ltypeId, rtypeId)))
{
}
else if (!noWarnings)
{
op_error(opname, ltypeId, rtypeId);
}
return (Operator) tup;
} /* oper() */
/* unary_oper_get_candidates()
* given opname and typeId, find all possible types for which
* a right/left unary operator named opname exists,
* such that typeId can be coerced to it
*/
static int
unary_oper_get_candidates(char *op,
Oid typeId,
CandidateList *candidates,
char rightleft)
{
CandidateList current_candidate;
Relation pg_operator_desc;
HeapScanDesc pg_operator_scan;
HeapTuple tup;
Form_pg_operator oper;
int ncandidates = 0;
static ScanKeyData opKey[2] = {
{0, Anum_pg_operator_oprname, F_NAMEEQ},
{0, Anum_pg_operator_oprkind, F_CHAREQ}};
*candidates = NULL;
fmgr_info(F_NAMEEQ, (FmgrInfo *) &opKey[0].sk_func);
opKey[0].sk_argument = NameGetDatum(op);
fmgr_info(F_CHAREQ, (FmgrInfo *) &opKey[1].sk_func);
opKey[1].sk_argument = CharGetDatum(rightleft);
pg_operator_desc = heap_openr(OperatorRelationName);
pg_operator_scan = heap_beginscan(pg_operator_desc,
0,
SnapshotSelf, /* ??? */
2,
opKey);
while (HeapTupleIsValid(tup = heap_getnext(pg_operator_scan, 0)))
{
current_candidate = (CandidateList) palloc(sizeof(struct _CandidateList));
current_candidate->args = (Oid *) palloc(sizeof(Oid));
oper = (Form_pg_operator) GETSTRUCT(tup);
if (rightleft == 'r')
current_candidate->args[0] = oper->oprleft;
else
current_candidate->args[0] = oper->oprright;
current_candidate->next = *candidates;
*candidates = current_candidate;
ncandidates++;
}
heap_endscan(pg_operator_scan);
heap_close(pg_operator_desc);
return ncandidates;
} /* unary_oper_get_candidates() */
/* Given unary right-side operator (operator on right), return oper struct */
/* arg-- type id */
Operator
right_oper(char *op, Oid arg)
{
HeapTuple tup;
CandidateList candidates;
int ncandidates;
Oid *targetOid;
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(arg),
ObjectIdGetDatum(InvalidOid),
CharGetDatum('r'));
if (!HeapTupleIsValid(tup))
{
ncandidates = unary_oper_get_candidates(op, arg, &candidates, 'r');
if (ncandidates == 0)
{
elog(ERROR, "Can't find right op '%s' for type %u", op, arg);
return NULL;
}
else if (ncandidates == 1)
{
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(candidates->args[0]),
ObjectIdGetDatum(InvalidOid),
CharGetDatum('r'));
Assert(HeapTupleIsValid(tup));
}
else
{
targetOid = oper_select_candidate(1, &arg, candidates);
if (targetOid != NULL)
{
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(*targetOid),
CharGetDatum('r'));
}
else
tup = NULL;
if (!HeapTupleIsValid(tup))
{
elog(ERROR, "Unable to convert right operator '%s' from type '%s'",
op, typeidTypeName(arg));
return NULL;
}
}
}
return (Operator) tup;
} /* right_oper() */
/* Given unary left-side operator (operator on left), return oper struct */
/* arg--type id */
Operator
left_oper(char *op, Oid arg)
{
HeapTuple tup;
CandidateList candidates;
int ncandidates;
Oid *targetOid;
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(arg),
CharGetDatum('l'));
if (!HeapTupleIsValid(tup))
{
ncandidates = unary_oper_get_candidates(op, arg, &candidates, 'l');
if (ncandidates == 0)
{
elog(ERROR, "Can't find left op '%s' for type %u", op, arg);
return NULL;
}
else if (ncandidates == 1)
{
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(candidates->args[0]),
CharGetDatum('l'));
Assert(HeapTupleIsValid(tup));
}
else
{
targetOid = oper_select_candidate(1, &arg, candidates);
if (targetOid != NULL)
{
tup = SearchSysCacheTuple(OPRNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(*targetOid),
CharGetDatum('l'));
}
else
tup = NULL;
if (!HeapTupleIsValid(tup))
{
elog(ERROR, "Unable to convert left operator '%s' from type '%s'",
op, typeidTypeName(arg));
return NULL;
}
}
}
return (Operator) tup;
} /* left_oper() */
/* op_error()
* Give a somewhat useful error message when the operator for two types
* is not found.
*/
static void
op_error(char *op, Oid arg1, Oid arg2)
{
Type tp1 = NULL,
tp2 = NULL;
if (typeidIsValid(arg1))
tp1 = typeidType(arg1);
else
{
elog(ERROR, "Left hand side of operator '%s' has an unknown type"
"\n\tProbably a bad attribute name", op);
}
if (typeidIsValid(arg2))
tp2 = typeidType(arg2);
else
{
elog(ERROR, "Right hand side of operator %s has an unknown type"
"\n\tProbably a bad attribute name", op);
}
elog(ERROR, "Unable to identify an operator '%s' for types '%s' and '%s'"
"\n\tYou will have to retype this query using an explicit cast",
op, typeTypeName(tp1), typeTypeName(tp2));
}
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