parse_oper.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

Operator
oper(List *opname, Oid ltypeId, Oid rtypeId, bool noError)
{
	FuncCandidateList clist;
	Oid			inputOids[2];
	Oid			operOid;
	FuncDetailCode fdresult = FUNCDETAIL_NOTFOUND;
	HeapTuple	tup = NULL;

	/* Get binary operators of given name */
	clist = OpernameGetCandidates(opname, 'b');

	/* No operators found? Then fail... */
	if (clist != NULL)
	{
		/*
		 * Check for an "exact" match.
		 */
		operOid = binary_oper_exact(ltypeId, rtypeId, clist);
		if (!OidIsValid(operOid))
		{
			/*
			 * Otherwise, search for the most suitable candidate.
			 */

			/*
			 * Unspecified type for one of the arguments? then use the other
			 * (XXX this is probably dead code?)
			 */
			if (rtypeId == InvalidOid)
				rtypeId = ltypeId;
			else if (ltypeId == InvalidOid)
				ltypeId = rtypeId;
			inputOids[0] = ltypeId;
			inputOids[1] = rtypeId;
			fdresult = oper_select_candidate(2, inputOids, clist, &operOid);
		}
		if (OidIsValid(operOid))
			tup = SearchSysCache(OPEROID,
								 ObjectIdGetDatum(operOid),
								 0, 0, 0);
	}

	if (!HeapTupleIsValid(tup) && !noError)
		op_error(opname, 'b', ltypeId, rtypeId, fdresult);

	return (Operator) tup;
}

/* compatible_oper()
 *	given an opname and input datatypes, find a compatible binary operator
 *
 *	This is tighter than oper() because it will not return an operator that
 *	requires coercion of the input datatypes (but binary-compatible operators
 *	are accepted).	Otherwise, the semantics are the same.
 */
Operator
compatible_oper(List *op, Oid arg1, Oid arg2, bool noError)
{
	Operator	optup;
	Form_pg_operator opform;

	/* oper() will find the best available match */
	optup = oper(op, arg1, arg2, noError);
	if (optup == (Operator) NULL)
		return (Operator) NULL; /* must be noError case */

	/* but is it good enough? */
	opform = (Form_pg_operator) GETSTRUCT(optup);
	if (IsBinaryCoercible(arg1, opform->oprleft) &&
		IsBinaryCoercible(arg2, opform->oprright))
		return optup;

	/* nope... */
	ReleaseSysCache(optup);

	if (!noError)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator requires run-time type coercion: %s",
						op_signature_string(op, 'b', arg1, arg2))));

	return (Operator) NULL;
}

/* compatible_oper_opid() -- get OID of a binary operator
 *
 * This is a convenience routine that extracts only the operator OID
 * from the result of compatible_oper().  InvalidOid is returned if the
 * lookup fails and noError is true.
 */
Oid
compatible_oper_opid(List *op, Oid arg1, Oid arg2, bool noError)
{
	Operator	optup;
	Oid			result;

	optup = compatible_oper(op, arg1, arg2, noError);
	if (optup != NULL)
	{
		result = oprid(optup);
		ReleaseSysCache(optup);
		return result;
	}
	return InvalidOid;
}


/* right_oper() -- search for a unary right operator (postfix operator)
 * Given operator name and type of arg, return oper struct.
 *
 * IMPORTANT: the returned operator (if any) is only promised to be
 * coercion-compatible with the input datatype.  Do not use this if
 * you need an exact- or binary-compatible match.
 *
 * 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
right_oper(List *op, Oid arg, bool noError)
{
	FuncCandidateList clist;
	Oid			operOid = InvalidOid;
	FuncDetailCode fdresult = FUNCDETAIL_NOTFOUND;
	HeapTuple	tup = NULL;

	/* Find candidates */
	clist = OpernameGetCandidates(op, 'r');

	if (clist != NULL)
	{
		/*
		 * First, quickly check to see if there is an exactly matching
		 * operator (there can be only one such entry in the list).
		 */
		FuncCandidateList clisti;

		for (clisti = clist; clisti != NULL; clisti = clisti->next)
		{
			if (arg == clisti->args[0])
			{
				operOid = clisti->oid;
				break;
			}
		}

		if (!OidIsValid(operOid))
		{
			/*
			 * We must run oper_select_candidate even if only one candidate,
			 * otherwise we may falsely return a non-type-compatible operator.
			 */
			fdresult = oper_select_candidate(1, &arg, clist, &operOid);
		}
		if (OidIsValid(operOid))
			tup = SearchSysCache(OPEROID,
								 ObjectIdGetDatum(operOid),
								 0, 0, 0);
	}

	if (!HeapTupleIsValid(tup) && !noError)
		op_error(op, 'r', arg, InvalidOid, fdresult);

	return (Operator) tup;
}


/* left_oper() -- search for a unary left operator (prefix operator)
 * Given operator name and type of arg, return oper struct.
 *
 * IMPORTANT: the returned operator (if any) is only promised to be
 * coercion-compatible with the input datatype.  Do not use this if
 * you need an exact- or binary-compatible match.
 *
 * 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
left_oper(List *op, Oid arg, bool noError)
{
	FuncCandidateList clist;
	Oid			operOid = InvalidOid;
	FuncDetailCode fdresult = FUNCDETAIL_NOTFOUND;
	HeapTuple	tup = NULL;

	/* Find candidates */
	clist = OpernameGetCandidates(op, 'l');

	if (clist != NULL)
	{
		/*
		 * First, quickly check to see if there is an exactly matching
		 * operator (there can be only one such entry in the list).
		 *
		 * The returned list has args in the form (0, oprright).  Move the
		 * useful data into args[0] to keep oper_select_candidate simple. XXX
		 * we are assuming here that we may scribble on the list!
		 */
		FuncCandidateList clisti;

		for (clisti = clist; clisti != NULL; clisti = clisti->next)
		{
			clisti->args[0] = clisti->args[1];
			if (arg == clisti->args[0])
			{
				operOid = clisti->oid;
				break;
			}
		}

		if (!OidIsValid(operOid))
		{
			/*
			 * We must run oper_select_candidate even if only one candidate,
			 * otherwise we may falsely return a non-type-compatible operator.
			 */
			fdresult = oper_select_candidate(1, &arg, clist, &operOid);
		}
		if (OidIsValid(operOid))
			tup = SearchSysCache(OPEROID,
								 ObjectIdGetDatum(operOid),
								 0, 0, 0);
	}

	if (!HeapTupleIsValid(tup) && !noError)
		op_error(op, 'l', InvalidOid, arg, fdresult);

	return (Operator) tup;
}

/*
 * op_signature_string
 *		Build a string representing an operator name, including arg type(s).
 *		The result is something like "integer + integer".
 *
 * This is typically used in the construction of operator-not-found error
 * messages.
 */
static const char *
op_signature_string(List *op, char oprkind, Oid arg1, Oid arg2)
{
	StringInfoData argbuf;

	initStringInfo(&argbuf);

	if (oprkind != 'l')
		appendStringInfo(&argbuf, "%s ", format_type_be(arg1));

	appendStringInfoString(&argbuf, NameListToString(op));

	if (oprkind != 'r')
		appendStringInfo(&argbuf, " %s", format_type_be(arg2));

	return argbuf.data;			/* return palloc'd string buffer */
}

/*
 * op_error - utility routine to complain about an unresolvable operator
 */
static void
op_error(List *op, char oprkind, Oid arg1, Oid arg2, FuncDetailCode fdresult)
{
	if (fdresult == FUNCDETAIL_MULTIPLE)
		ereport(ERROR,
				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
				 errmsg("operator is not unique: %s",
						op_signature_string(op, oprkind, arg1, arg2)),
				 errhint("Could not choose a best candidate operator. "
						 "You may need to add explicit type casts.")));
	else
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("operator does not exist: %s",
						op_signature_string(op, oprkind, arg1, arg2)),
		  errhint("No operator matches the given name and argument type(s). "
				  "You may need to add explicit type casts.")));
}

/*
 * make_op()
 *		Operator expression construction.
 *
 * Transform operator expression ensuring type compatibility.
 * This is where some type conversion happens.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Expr *
make_op(ParseState *pstate, List *opname, Node *ltree, Node *rtree)
{
	Oid			ltypeId,
				rtypeId;
	Operator	tup;
	Expr	   *result;

	/* Select the operator */
	if (rtree == NULL)
	{
		/* right operator */
		ltypeId = exprType(ltree);
		rtypeId = InvalidOid;
		tup = right_oper(opname, ltypeId, false);
	}
	else if (ltree == NULL)
	{
		/* left operator */
		rtypeId = exprType(rtree);
		ltypeId = InvalidOid;
		tup = left_oper(opname, rtypeId, false);
	}
	else
	{
		/* otherwise, binary operator */
		ltypeId = exprType(ltree);
		rtypeId = exprType(rtree);
		tup = oper(opname, ltypeId, rtypeId, false);
	}

	/* Do typecasting and build the expression tree */
	result = make_op_expr(pstate, tup, ltree, rtree, ltypeId, rtypeId);

	ReleaseSysCache(tup);

	return result;
}

/*
 * make_scalar_array_op()
 *		Build expression tree for "scalar op ANY/ALL (array)" construct.
 */
Expr *
make_scalar_array_op(ParseState *pstate, List *opname,
					 bool useOr,
					 Node *ltree, Node *rtree)
{
	Oid			ltypeId,
				rtypeId,
				atypeId,
				res_atypeId;
	Operator	tup;
	Form_pg_operator opform;
	Oid			actual_arg_types[2];
	Oid			declared_arg_types[2];
	List	   *args;
	Oid			rettype;
	ScalarArrayOpExpr *result;

	ltypeId = exprType(ltree);
	atypeId = exprType(rtree);

	/*
	 * The right-hand input of the operator will be the element type of the
	 * array.  However, if we currently have just an untyped literal on the
	 * right, stay with that and hope we can resolve the operator.
	 */
	if (atypeId == UNKNOWNOID)
		rtypeId = UNKNOWNOID;
	else
	{
		rtypeId = get_element_type(atypeId);
		if (!OidIsValid(rtypeId))
			ereport(ERROR,
					(errcode(ERRCODE_WRONG_OBJECT_TYPE),
				 errmsg("op ANY/ALL (array) requires array on right side")));
	}

	/* Now resolve the operator */
	tup = oper(opname, ltypeId, rtypeId, false);
	opform = (Form_pg_operator) GETSTRUCT(tup);

	args = list_make2(ltree, rtree);
	actual_arg_types[0] = ltypeId;
	actual_arg_types[1] = rtypeId;
	declared_arg_types[0] = opform->oprleft;
	declared_arg_types[1] = opform->oprright;

	/*
	 * enforce consistency with ANYARRAY and ANYELEMENT argument and return
	 * types, possibly adjusting return type or declared_arg_types (which will
	 * be used as the cast destination by make_fn_arguments)
	 */
	rettype = enforce_generic_type_consistency(actual_arg_types,
											   declared_arg_types,
											   2,
											   opform->oprresult);

	/*
	 * Check that operator result is boolean
	 */
	if (rettype != BOOLOID)
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
		   errmsg("op ANY/ALL (array) requires operator to yield boolean")));
	if (get_func_retset(opform->oprcode))
		ereport(ERROR,
				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
		errmsg("op ANY/ALL (array) requires operator not to return a set")));

	/*
	 * Now switch back to the array type on the right, arranging for any
	 * needed cast to be applied.
	 */
	res_atypeId = get_array_type(declared_arg_types[1]);
	if (!OidIsValid(res_atypeId))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("could not find array type for data type %s",
						format_type_be(declared_arg_types[1]))));
	actual_arg_types[1] = atypeId;
	declared_arg_types[1] = res_atypeId;

	/* perform the necessary typecasting of arguments */
	make_fn_arguments(pstate, args, actual_arg_types, declared_arg_types);

	/* and build the expression node */
	result = makeNode(ScalarArrayOpExpr);
	result->opno = oprid(tup);
	result->opfuncid = InvalidOid;
	result->useOr = useOr;
	result->args = args;

	ReleaseSysCache(tup);

	return (Expr *) result;
}

/*
 * make_op_expr()
 *		Build operator expression using an already-looked-up operator.
 *
 * As with coerce_type, pstate may be NULL if no special unknown-Param
 * processing is wanted.
 */
Expr *
make_op_expr(ParseState *pstate, Operator op,
			 Node *ltree, Node *rtree,
			 Oid ltypeId, Oid rtypeId)
{
	Form_pg_operator opform = (Form_pg_operator) GETSTRUCT(op);
	Oid			actual_arg_types[2];
	Oid			declared_arg_types[2];
	int			nargs;
	List	   *args;
	Oid			rettype;
	OpExpr	   *result;

	if (rtree == NULL)
	{
		/* right operator */
		args = list_make1(ltree);
		actual_arg_types[0] = ltypeId;
		declared_arg_types[0] = opform->oprleft;
		nargs = 1;
	}
	else if (ltree == NULL)
	{
		/* left operator */
		args = list_make1(rtree);
		actual_arg_types[0] = rtypeId;
		declared_arg_types[0] = opform->oprright;
		nargs = 1;
	}
	else
	{
		/* otherwise, binary operator */
		args = list_make2(ltree, rtree);
		actual_arg_types[0] = ltypeId;
		actual_arg_types[1] = rtypeId;
		declared_arg_types[0] = opform->oprleft;
		declared_arg_types[1] = opform->oprright;
		nargs = 2;
	}

	/*
	 * enforce consistency with ANYARRAY and ANYELEMENT argument and return
	 * types, possibly adjusting return type or declared_arg_types (which will
	 * be used as the cast destination by make_fn_arguments)
	 */
	rettype = enforce_generic_type_consistency(actual_arg_types,
											   declared_arg_types,
											   nargs,
											   opform->oprresult);

	/* perform the necessary typecasting of arguments */
	make_fn_arguments(pstate, args, actual_arg_types, declared_arg_types);

	/* and build the expression node */
	result = makeNode(OpExpr);
	result->opno = oprid(op);
	result->opfuncid = InvalidOid;
	result->opresulttype = rettype;
	result->opretset = get_func_retset(opform->oprcode);
	result->args = args;

	return (Expr *) result;
}