/*-------------------------------------------------------------------------
*
* parse_oper.c
* handle operator things for 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_oper.c,v 1.46 2001/01/24 19:43:02 momjian 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/fmgroids.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 *opname,
CandidateList *candidates,
char rightleft);
static void op_error(char *op, Oid arg1, Oid arg2);
static void unary_op_error(char *op, Oid arg, bool is_left_op);
/* Select an ordering operator for the given datatype */
Oid
any_ordering_op(Oid restype)
{
Oid order_opid;
order_opid = oper_oid("<", restype, restype, true);
if (!OidIsValid(order_opid))
elog(ERROR, "Unable to identify an ordering operator '%s' for type '%s'"
"\n\tUse an explicit ordering operator or modify the query",
"<", typeidTypeName(restype));
return order_opid;
}
/* given operator tuple, 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 ncandidates = 0;
ScanKeyData opKey[2];
*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'));
pg_operator_desc = heap_openr(OperatorRelationName, AccessShareLock);
pg_operator_scan = heap_beginscan(pg_operator_desc,
0,
SnapshotSelf, /* ??? */
2,
opKey);
while (HeapTupleIsValid(tup = heap_getnext(pg_operator_scan, 0)))
{
oper = (Form_pg_operator) GETSTRUCT(tup);
current_candidate = (CandidateList) palloc(sizeof(struct _CandidateList));
current_candidate->args = (Oid *) palloc(2 * sizeof(Oid));
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, AccessShareLock);
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.
*
* By design, this is pretty similar to func_select_candidate in parse_func.c.
* However, we can do a couple of extra things here because we know we can
* have no more than two args to deal with. Also, the calling convention
* is a little different: we must prune away "candidates" that aren't actually
* coercion-compatible with the input types, whereas in parse_func.c that
* gets done by match_argtypes before func_select_candidate is called.
*
* 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 coercions 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;
Oid current_type;
int unknownOids;
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;
/*
* First, delete any candidates that cannot actually accept the given
* input types, whether directly or by coercion. (Note that
* can_coerce_type will assume that UNKNOWN inputs are coercible to
* anything, so candidates will not be eliminated on that basis.)
*/
ncandidates = 0;
last_candidate = NULL;
for (current_candidate = candidates;
current_candidate != NULL;
current_candidate = current_candidate->next)
{
if (can_coerce_type(nargs, input_typeids, current_candidate->args))
{
if (last_candidate == NULL)
{
candidates = current_candidate;
last_candidate = current_candidate;
ncandidates = 1;
}
else
{
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;
/* Done if no candidate or only one candidate survives */
if (ncandidates == 0)
return NULL;
if (ncandidates == 1)
return candidates->args;
/*
* 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.
*
* First try: if we have an unknown and a non-unknown input, see whether
* there is a candidate all of whose input types are the same as the
* known input type (there can be at most one such candidate). If so,
* use that candidate. NOTE that this is cool only because operators
* can't have more than 2 args, so taking the last non-unknown as
* current_type can yield only one possibility if there is also an
* unknown.
*/
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])
nmatch++;
}
if (nmatch == nargs)
return current_typeids;
}
}
/*
* Second try: same algorithm as for unknown resolution in parse_func.c.
*
* 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 */
} /* oper_select_candidate() */
/* oper_exact()
* Given operator, types of arg1 and arg2, return oper struct or NULL.
*
* NOTE: on success, the returned object is a syscache entry. The caller
* must ReleaseSysCache() the entry when done with it.
*/
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 = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(arg1),
ObjectIdGetDatum(arg2),
CharGetDatum('b'));
return (Operator) tup;
}
/* oper_inexact()
* Given operator, types of arg1 and arg2, return oper struct or NULL.
*
* NOTE: on success, the returned object is a syscache entry. The caller
* must ReleaseSysCache() the entry when done with it.
*/
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 = SearchSysCache(OPERNAME,
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 = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(targetOids[0]),
ObjectIdGetDatum(targetOids[1]),
CharGetDatum('b'));
}
else
tup = NULL;
}
return (Operator) tup;
}
/* oper() -- search for a binary operator
* Given operator name, types of arg1 and arg2, return oper struct.
*
* If no matching operator found, return NULL if noError is true,
* raise an error if it is false.
*
* NOTE: on success, the returned object is a syscache entry. The caller
* must ReleaseSysCache() the entry when done with it.
*/
Operator
oper(char *opname, Oid ltypeId, Oid rtypeId, bool noError)
{
HeapTuple tup;
/* check for exact match on this operator... */
if (HeapTupleIsValid(tup = oper_exact(opname, ltypeId, rtypeId)))
return (Operator) tup;
/* try to find a match on likely candidates... */
if (HeapTupleIsValid(tup = oper_inexact(opname, ltypeId, rtypeId)))
return (Operator) tup;
if (!noError)
op_error(opname, ltypeId, rtypeId);
return (Operator) NULL;
}
/* oper_oid() -- get OID of a binary operator
*
* This is a convenience routine that extracts only the operator OID
* from the result of oper(). InvalidOid is returned if the lookup
* fails and noError is true.
*/
Oid
oper_oid(char *op, Oid arg1, Oid arg2, bool noError)
{
Operator optup;
Oid result;
optup = oper(op, arg1, arg2, noError);
if (optup != NULL)
{
result = oprid(optup);
ReleaseSysCache(optup);
return result;
}
return InvalidOid;
}
/* unary_oper_get_candidates()
* given opname, find all possible types for which
* a right/left unary operator named opname exists.
* Build a list of the candidate input types.
* Returns number of candidates found.
*/
static int
unary_oper_get_candidates(char *opname,
CandidateList *candidates,
char rightleft)
{
CandidateList current_candidate;
Relation pg_operator_desc;
HeapScanDesc pg_operator_scan;
HeapTuple tup;
Form_pg_operator oper;
int ncandidates = 0;
ScanKeyData opKey[2];
*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(rightleft));
pg_operator_desc = heap_openr(OperatorRelationName, AccessShareLock);
pg_operator_scan = heap_beginscan(pg_operator_desc,
0,
SnapshotSelf, /* ??? */
2,
opKey);
while (HeapTupleIsValid(tup = heap_getnext(pg_operator_scan, 0)))
{
oper = (Form_pg_operator) GETSTRUCT(tup);
current_candidate = (CandidateList) palloc(sizeof(struct _CandidateList));
current_candidate->args = (Oid *) palloc(sizeof(Oid));
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, AccessShareLock);
return ncandidates;
} /* unary_oper_get_candidates() */
/* Given unary right operator (operator on right), return oper struct
*
* Always raises error on failure.
*
* NOTE: on success, the returned object is a syscache entry. The caller
* must ReleaseSysCache() the entry when done with it.
*/
Operator
right_oper(char *op, Oid arg)
{
HeapTuple tup;
CandidateList candidates;
int ncandidates;
Oid *targetOid;
/* Try for exact match */
tup = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(arg),
ObjectIdGetDatum(InvalidOid),
CharGetDatum('r'));
if (!HeapTupleIsValid(tup))
{
/* Try for inexact matches */
ncandidates = unary_oper_get_candidates(op, &candidates, 'r');
if (ncandidates == 0)
unary_op_error(op, arg, FALSE);
else if (ncandidates == 1)
{
tup = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(candidates->args[0]),
ObjectIdGetDatum(InvalidOid),
CharGetDatum('r'));
}
else
{
targetOid = oper_select_candidate(1, &arg, candidates);
if (targetOid != NULL)
tup = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(targetOid[0]),
ObjectIdGetDatum(InvalidOid),
CharGetDatum('r'));
}
if (!HeapTupleIsValid(tup))
unary_op_error(op, arg, FALSE);
}
return (Operator) tup;
} /* right_oper() */
/* Given unary left operator (operator on left), return oper struct
*
* Always raises error on failure.
*
* NOTE: on success, the returned object is a syscache entry. The caller
* must ReleaseSysCache() the entry when done with it.
*/
Operator
left_oper(char *op, Oid arg)
{
HeapTuple tup;
CandidateList candidates;
int ncandidates;
Oid *targetOid;
/* Try for exact match */
tup = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(arg),
CharGetDatum('l'));
if (!HeapTupleIsValid(tup))
{
/* Try for inexact matches */
ncandidates = unary_oper_get_candidates(op, &candidates, 'l');
if (ncandidates == 0)
unary_op_error(op, arg, TRUE);
else if (ncandidates == 1)
{
tup = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(candidates->args[0]),
CharGetDatum('l'));
}
else
{
targetOid = oper_select_candidate(1, &arg, candidates);
if (targetOid != NULL)
tup = SearchSysCache(OPERNAME,
PointerGetDatum(op),
ObjectIdGetDatum(InvalidOid),
ObjectIdGetDatum(targetOid[0]),
CharGetDatum('l'));
}
if (!HeapTupleIsValid(tup))
unary_op_error(op, arg, TRUE);
}
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)
{
if (!typeidIsValid(arg1))
elog(ERROR, "Left hand side of operator '%s' has an unknown type"
"\n\tProbably a bad attribute name", op);
if (!typeidIsValid(arg2))
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, typeidTypeName(arg1), typeidTypeName(arg2));
}
/* unary_op_error()
* Give a somewhat useful error message when the operator for one type
* is not found.
*/
static void
unary_op_error(char *op, Oid arg, bool is_left_op)
{
if (!typeidIsValid(arg))
elog(ERROR, "Argument of %s operator '%s' has an unknown type"
"\n\tProbably a bad attribute name",
(is_left_op ? "left" : "right"),
op);
elog(ERROR, "Unable to identify a %s operator '%s' for type '%s'"
"\n\tYou may need to add parentheses or an explicit cast",
(is_left_op ? "left" : "right"),
op, typeidTypeName(arg));
}