parse_oper.c
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上传日期:2007-01-07
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文件大小:19k
- /*-------------------------------------------------------------------------
- *
- * parse_oper.h
- * handle operator things for parser
- *
- * Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- * $Header: /usr/local/cvsroot/pgsql/src/backend/parser/parse_oper.c,v 1.25 1999/05/25 16:10:18 momjian Exp $
- *
- *-------------------------------------------------------------------------
- */
- #include <string.h>
- #include "postgres.h"
- #include "access/heapam.h"
- #include "access/relscan.h"
- #include "catalog/catname.h"
- #include "catalog/pg_operator.h"
- #include "catalog/pg_type.h"
- #include "fmgr.h"
- #include "parser/parse_oper.h"
- #include "parser/parse_type.h"
- #include "parser/parse_coerce.h"
- #include "storage/bufmgr.h"
- #include "utils/syscache.h"
- static Oid *oper_select_candidate(int nargs, Oid *input_typeids,
- CandidateList candidates);
- static int binary_oper_get_candidates(char *opname,
- Oid leftTypeId,
- Oid rightTypeId,
- 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'"
- "ntUse 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, leftTypeId and rightTypeId,
- * find all possible (arg1, arg2) pairs for which an operator named
- * opname exists, such that leftTypeId can be coerced to arg1 and
- * rightTypeId can be coerced to arg2
- */
- static int
- binary_oper_get_candidates(char *opname,
- Oid leftTypeId,
- Oid rightTypeId,
- 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... */
- else
- last_candidate->next = NULL;
- }
- if (ncandidates <= 1)
- {
- if (!can_coerce_type(1, &input_typeids[0], &candidates->args[0])
- || !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++)
- {
- current_category = TypeCategory(current_typeids[i]);
- if (input_typeids[i] != UNKNOWNOID)
- {
- if (current_typeids[i] == input_typeids[i])
- nmatch++;
- else if (IsPreferredType(current_category, current_typeids[i])
- && can_coerce_type(1, &input_typeids[i], ¤t_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++;
- }
- else
- last_candidate->next = NULL;
- }
- if (ncandidates <= 1)
- {
- if (!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)
- {
- nmatch = 0;
- for (i = 0; i < nargs; i++)
- {
- current_typeids = current_candidate->args;
- 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;
- for (current_candidate = candidates;
- current_candidate != NULL;
- current_candidate = current_candidate->next)
- {
- if (can_coerce_type(1, &input_typeids[0], ¤t_candidate->args[0])
- && can_coerce_type(1, &input_typeids[1], ¤t_candidate->args[1]))
- ncandidates++;
- }
- return (ncandidates == 1) ? candidates->args : NULL;
- } /* oper_select_candidate() */
- /* oper_exact()
- * Given operator, and arguments, return oper struct.
- * Inputs:
- * arg1, arg2: Type IDs
- */
- Operator
- oper_exact(char *op, Oid arg1, Oid arg2, Node **ltree, Node **rtree, bool noWarnings)
- {
- HeapTuple tup;
- Node *tree;
- /* 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'));
- /*
- * Did not find anything? then try flipping arguments on a commutative
- * operator...
- */
- if (!HeapTupleIsValid(tup) && (arg1 != arg2))
- {
- tup = SearchSysCacheTuple(OPRNAME,
- PointerGetDatum(op),
- ObjectIdGetDatum(arg2),
- ObjectIdGetDatum(arg1),
- CharGetDatum('b'));
- if (HeapTupleIsValid(tup))
- {
- Form_pg_operator opform;
- opform = (Form_pg_operator) GETSTRUCT(tup);
- if (opform->oprcom == tup->t_data->t_oid)
- {
- if ((ltree != NULL) && (rtree != NULL))
- {
- tree = *ltree;
- *ltree = *rtree;
- *rtree = tree;
- }
- }
- /* disable for now... - thomas 1998-05-14 */
- else
- tup = NULL;
- }
- if (!HeapTupleIsValid(tup) && (!noWarnings))
- op_error(op, arg1, arg2);
- }
- return tup;
- } /* oper_exact() */
- /* oper_inexact()
- * Given operator, types of arg1, and arg2, return oper struct.
- * Inputs:
- * arg1, arg2: Type IDs
- */
- Operator
- oper_inexact(char *op, Oid arg1, Oid arg2, Node **ltree, Node **rtree, bool noWarnings)
- {
- 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, arg1, arg2, &candidates);
- /* No operators found? Then throw error or return null... */
- if (ncandidates == 0)
- {
- if (!noWarnings)
- op_error(op, arg1, arg2);
- 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;
- /* Could not choose one, for whatever reason... */
- if (!HeapTupleIsValid(tup))
- {
- if (!noWarnings)
- {
- elog(ERROR, "Unable to identify an operator '%s' for types '%s' and '%s'"
- "ntYou will have to retype this query using an explicit cast",
- op, typeTypeName(typeidType(arg1)), typeTypeName(typeidType(arg2)));
- }
- return 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, NULL, NULL, TRUE)))
- {
- }
- /* try to find a match on likely candidates... */
- else if (HeapTupleIsValid(tup = oper_inexact(opname, ltypeId, rtypeId, NULL, NULL, TRUE)))
- {
- }
- else if (!noWarnings)
- {
- elog(ERROR, "Unable to identify a binary operator '%s' for types %s and %s",
- opname, typeTypeName(typeidType(ltypeId)), typeTypeName(typeidType(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"
- "ntProbably a bad attribute name", op);
- }
- if (typeidIsValid(arg2))
- tp2 = typeidType(arg2);
- else
- {
- elog(ERROR, "Right hand side of operator %s has an unknown type"
- "ntProbably a bad attribute name", op);
- }
- elog(ERROR, "There is no operator '%s' for types '%s' and '%s'"
- "ntYou will either have to retype this query using an explicit cast,"
- "ntor you will have to define the operator using CREATE OPERATOR",
- op, typeTypeName(tp1), typeTypeName(tp2));
- }