ruleutils.c

关系型数据库 Postgresql 6.5.2

		return pstrdup("");

	buf[0] = '\0';

	/* ----------
	 * Each level of get_rule_expr must return an indivisible term
	 * (parenthesized if necessary) to ensure result is reparsed into
	 * the same expression tree.
	 *
	 * There might be some work left here to support additional node types...
	 * ----------
	 */
	switch (nodeTag(node))
	{
		case T_Const:
			return get_const_expr((Const *) node);
			break;

		case T_Var:
			{
				Var		   *var = (Var *) node;
				RangeTblEntry *rte = get_rte_for_var(var, qh);

				if (!strcmp(rte->refname, "*NEW*"))
					strcat(buf, "new.");
				else if (!strcmp(rte->refname, "*CURRENT*"))
					strcat(buf, "old.");
				else
				{
					strcat(buf, "\"");
					strcat(buf, rte->refname);
					strcat(buf, "\".");
				}
				strcat(buf, "\"");
				strcat(buf, get_attribute_name(rte->relid, var->varattno));
				strcat(buf, "\"");

				return pstrdup(buf);
			}
			break;

		case T_Expr:
			{
				Expr	   *expr = (Expr *) node;
				List	   *args = expr->args;

				/* ----------
				 * Expr nodes have to be handled a bit detailed
				 * ----------
				 */
				switch (expr->opType)
				{
					case OP_EXPR:
						strcat(buf, "(");
						if (length(args) == 2)
						{
							/* binary operator */
							strcat(buf,
								   get_rule_expr(qh, rt_index,
												 (Node *) lfirst(args),
												 varprefix));
							strcat(buf, " ");
							strcat(buf,
								   get_opname(((Oper *) expr->oper)->opno));
							strcat(buf, " ");
							strcat(buf,
								   get_rule_expr(qh, rt_index,
												 (Node *) lsecond(args),
												 varprefix));
						}
						else
						{
							/* unary operator --- but which side? */
							Oid			opno = ((Oper *) expr->oper)->opno;
							HeapTuple	tp;
							Form_pg_operator optup;

							tp = SearchSysCacheTuple(OPROID,
													 ObjectIdGetDatum(opno),
													 0, 0, 0);
							Assert(HeapTupleIsValid(tp));
							optup = (Form_pg_operator) GETSTRUCT(tp);
							switch (optup->oprkind)
							{
								case 'l':
									strcat(buf, get_opname(opno));
									strcat(buf, " ");
									strcat(buf,
										   get_rule_expr(qh, rt_index,
														 (Node *) lfirst(args),
														 varprefix));
									break;
								case 'r':
									strcat(buf,
										   get_rule_expr(qh, rt_index,
														 (Node *) lfirst(args),
														 varprefix));
									strcat(buf, " ");
									strcat(buf, get_opname(opno));
									break;
								default:
									elog(ERROR, "get_rule_expr: bogus oprkind");
							}
						}
						strcat(buf, ")");
						return pstrdup(buf);
						break;

					case OR_EXPR:
						strcat(buf, "(");
						strcat(buf, get_rule_expr(qh, rt_index,
												  (Node *) lfirst(args),
												  varprefix));
						/* It's not clear that we can ever see N-argument
						 * OR/AND clauses here, but might as well cope...
						 */
						while ((args = lnext(args)) != NIL)
						{
							strcat(buf, " OR ");
							strcat(buf, get_rule_expr(qh, rt_index,
													  (Node *) lfirst(args),
													  varprefix));
						}
						strcat(buf, ")");
						return pstrdup(buf);
						break;

					case AND_EXPR:
						strcat(buf, "(");
						strcat(buf, get_rule_expr(qh, rt_index,
												  (Node *) lfirst(args),
												  varprefix));
						while ((args = lnext(args)) != NIL)
						{
							strcat(buf, " AND ");
							strcat(buf, get_rule_expr(qh, rt_index,
													  (Node *) lfirst(args),
													  varprefix));
						}
						strcat(buf, ")");
						return pstrdup(buf);
						break;

					case NOT_EXPR:
						strcat(buf, "(NOT ");
						strcat(buf, get_rule_expr(qh, rt_index,
											   (Node *) get_leftop(expr),
												  varprefix));
						strcat(buf, ")");
						return pstrdup(buf);
						break;

					case FUNC_EXPR:
						return get_func_expr(qh, rt_index,
											 (Expr *) node,
											 varprefix);
						break;

					default:
						printf("\n%s\n", nodeToString(node));
						elog(ERROR, "get_rule_expr: expr type not supported");
				}
			}
			break;

		case T_Aggref:
			{
				Aggref	   *aggref = (Aggref *) node;

				strcat(buf, "\"");
				strcat(buf, aggref->aggname);
				strcat(buf, "\"(");
				strcat(buf, get_rule_expr(qh, rt_index,
								  (Node *) (aggref->target), varprefix));
				strcat(buf, ")");
				return pstrdup(buf);
			}
			break;

		case T_ArrayRef:
			{
				ArrayRef   *aref = (ArrayRef *) node;
				List	   *lowlist;
				List	   *uplist;

				strcat(buf, get_rule_expr(qh, rt_index,
										  aref->refexpr, varprefix));
				lowlist = aref->reflowerindexpr;
				foreach(uplist, aref->refupperindexpr)
				{
					strcat(buf, "[");
					if (lowlist)
					{
						strcat(buf, get_rule_expr(qh, rt_index,
												  (Node *) lfirst(lowlist),
												  varprefix));
						strcat(buf, ":");
						lowlist = lnext(lowlist);
					}
					strcat(buf, get_rule_expr(qh, rt_index,
											  (Node *) lfirst(uplist),
											  varprefix));
					strcat(buf, "]");
				}
				/* XXX need to do anything with refassgnexpr? */
				return pstrdup(buf);
			}
			break;

		case T_CaseExpr:
			{
				CaseExpr   *caseexpr = (CaseExpr *) node;
				List	   *temp;

				strcat(buf, "CASE");
				foreach(temp, caseexpr->args)
				{
					CaseWhen   *when = (CaseWhen *) lfirst(temp);

					strcat(buf, " WHEN ");
					strcat(buf, get_rule_expr(qh, rt_index,
											  when->expr, varprefix));
					strcat(buf, " THEN ");
					strcat(buf, get_rule_expr(qh, rt_index,
											  when->result, varprefix));
				}
				strcat(buf, " ELSE ");
				strcat(buf, get_rule_expr(qh, rt_index,
										  caseexpr->defresult, varprefix));
				strcat(buf, " END");
				return pstrdup(buf);
			}
			break;

		case T_SubLink:
			return get_sublink_expr(qh, rt_index, node, varprefix);
			break;

		default:
			printf("\n%s\n", nodeToString(node));
			elog(ERROR, "get_ruledef of %s: unknown node type %d in get_rule_expr()",
				 rulename, nodeTag(node));
			break;
	}

	return FALSE;
}


/* ----------
 * get_func_expr			- Parse back a Func node
 * ----------
 */
static char *
get_func_expr(QryHier *qh, int rt_index, Expr *expr, bool varprefix)
{
	char		buf[BUFSIZE];
	HeapTuple	proctup;
	Form_pg_proc procStruct;
	List	   *l;
	char	   *sep;
	Func	   *func = (Func *) (expr->oper);
	char	   *proname;

	/* ----------
	 * Get the functions pg_proc tuple
	 * ----------
	 */
	proctup = SearchSysCacheTuple(PROOID,
								ObjectIdGetDatum(func->funcid), 0, 0, 0);
	if (!HeapTupleIsValid(proctup))
		elog(ERROR, "cache lookup for proc %u failed", func->funcid);

	procStruct = (Form_pg_proc) GETSTRUCT(proctup);
	proname = nameout(&(procStruct->proname));

	if (procStruct->pronargs == 1 && procStruct->proargtypes[0] == InvalidOid)
	{
		if (!strcmp(proname, "nullvalue"))
		{
			strcpy(buf, "(");
			strcat(buf, get_rule_expr(qh, rt_index, lfirst(expr->args),
									  varprefix));
			strcat(buf, " ISNULL)");
			return pstrdup(buf);
		}
		if (!strcmp(proname, "nonnullvalue"))
		{
			strcpy(buf, "(");
			strcat(buf, get_rule_expr(qh, rt_index, lfirst(expr->args),
									  varprefix));
			strcat(buf, " NOTNULL)");
			return pstrdup(buf);
		}
	}

	/* ----------
	 * Build a string of proname(args)
	 * ----------
	 */
	strcpy(buf, "\"");
	strcat(buf, proname);
	strcat(buf, "\"(");
	sep = "";
	foreach(l, expr->args)
	{
		strcat(buf, sep);
		sep = ", ";
		strcat(buf, get_rule_expr(qh, rt_index, lfirst(l), varprefix));
	}
	strcat(buf, ")");

	/* ----------
	 * Copy the function call string into allocated space and return it
	 * ----------
	 */
	return pstrdup(buf);
}


/* ----------
 * get_tle_expr				- A target list expression is a bit
 *					  different from a normal expression.
 *					  If the target column has an
 *					  an atttypmod, the parser usually
 *					  puts a padding-/cut-function call
 *					  around the expression itself. We
 *					  we must get rid of it, otherwise
 *					  dump/reload/dump... would blow up
 *					  the expressions.
 * ----------
 */
static char *
get_tle_expr(QryHier *qh, int rt_index, TargetEntry *tle, bool varprefix)
{
	Expr	   *expr = (Expr *) (tle->expr);
	Func	   *func;
	HeapTuple	tup;
	Form_pg_proc procStruct;
	Form_pg_type typeStruct;
	Const	   *second_arg;

	/* ----------
	 * Check if the result has an atttypmod and if the
	 * expression in the targetlist entry is a function call
	 * ----------
	 */
	if (tle->resdom->restypmod < 0 ||
		! IsA(expr, Expr) ||
		expr->opType != FUNC_EXPR)
		return get_rule_expr(qh, rt_index, tle->expr, varprefix);

	func = (Func *) (expr->oper);

	/* ----------
	 * Get the functions pg_proc tuple
	 * ----------
	 */
	tup = SearchSysCacheTuple(PROOID,
							  ObjectIdGetDatum(func->funcid), 0, 0, 0);
	if (!HeapTupleIsValid(tup))
		elog(ERROR, "cache lookup for proc %u failed", func->funcid);
	procStruct = (Form_pg_proc) GETSTRUCT(tup);

	/* ----------
	 * It must be a function with two arguments where the first
	 * is of the same type as the return value and the second is
	 * an int4.
	 * ----------
	 */
	if (procStruct->pronargs != 2 ||
		procStruct->prorettype != procStruct->proargtypes[0] ||
		procStruct->proargtypes[1] != INT4OID)
		return get_rule_expr(qh, rt_index, tle->expr, varprefix);

	/*
	 * Furthermore, the name of the function must be the same
	 * as the argument/result type name.
	 */
	tup = SearchSysCacheTuple(TYPOID,
							  ObjectIdGetDatum(procStruct->prorettype),
							  0, 0, 0);
	if (!HeapTupleIsValid(tup))
		elog(ERROR, "cache lookup for type %u failed",
			 procStruct->prorettype);
	typeStruct = (Form_pg_type) GETSTRUCT(tup);
	if (strncmp(procStruct->proname.data, typeStruct->typname.data,
				NAMEDATALEN) != 0)
        return get_rule_expr(qh, rt_index, tle->expr, varprefix);

	/* ----------
	 * Finally (to be totally safe) the second argument must be a
	 * const and match the value in the results atttypmod.
	 * ----------
	 */
	second_arg = (Const *) nth(1, expr->args);
	if (! IsA(second_arg, Const) ||
		((int4) second_arg->constvalue) != tle->resdom->restypmod)
		return get_rule_expr(qh, rt_index, tle->expr, varprefix);

	/* ----------
	 * Whow - got it. Now get rid of the padding function
	 * ----------
	 */
	return get_rule_expr(qh, rt_index, lfirst(expr->args), varprefix);
}


/* ----------
 * get_const_expr			- Make a string representation
 *					  with the type cast out of a Const
 * ----------
 */
static char *
get_const_expr(Const *constval)
{
	HeapTuple	typetup;
	Form_pg_type typeStruct;
	FmgrInfo	finfo_output;
	char	   *extval;
	bool		isnull = FALSE;
	char		buf[BUFSIZE];
	char		namebuf[64];

	if (constval->constisnull)
		return pstrdup("NULL");

	typetup = SearchSysCacheTuple(TYPOID,
						 ObjectIdGetDatum(constval->consttype), 0, 0, 0);
	if (!HeapTupleIsValid(typetup))
		elog(ERROR, "cache lookup of type %u failed", constval->consttype);

	typeStruct = (Form_pg_type) GETSTRUCT(typetup);

	fmgr_info(typeStruct->typoutput, &finfo_output);
	extval = (char *) (*fmgr_faddr(&finfo_output)) (constval->constvalue,
													&isnull, -1);

	sprintf(namebuf, "::\"%s\"", nameout(&(typeStruct->typname)));
	if (strcmp(namebuf, "::unknown") == 0)
		namebuf[0] = '\0';
	sprintf(buf, "'%s'%s", extval, namebuf);
	return pstrdup(buf);
}


/* ----------
 * get_sublink_expr			- Parse back a sublink
 * ----------
 */
static char *
get_sublink_expr(QryHier *qh, int rt_index, Node *node, bool varprefix)
{
	SubLink    *sublink = (SubLink *) node;
	Query	   *query = (Query *) (sublink->subselect);
	Expr	   *expr;
	List	   *l;
	char	   *sep;
	char		buf[BUFSIZE];

	buf[0] = '\0';

	strcat(buf, "(");

	if (sublink->lefthand != NULL)
	{
		if (length(sublink->lefthand) > 1)
			strcat(buf, "(");

		sep = "";
		foreach(l, sublink->lefthand)
		{
			strcat(buf, sep);
			sep = ", ";
			strcat(buf, get_rule_expr(qh, rt_index,
									  lfirst(l), varprefix));
		}

		if (length(sublink->lefthand) > 1)
			strcat(buf, ") ");
		else
			strcat(buf, " ");
	}

	switch (sublink->subLinkType)
	{
		case EXISTS_SUBLINK:
			strcat(buf, "EXISTS ");
			break;

		case ANY_SUBLINK:
			expr = (Expr *) lfirst(sublink->oper);
			strcat(buf, get_opname(((Oper *) (expr->oper))->opno));
			strcat(buf, " ANY ");
			break;

		case ALL_SUBLINK:
			expr = (Expr *) lfirst(sublink->oper);
			strcat(buf, get_opname(((Oper *) (expr->oper))->opno));
			strcat(buf, " ALL ");
			break;

		case EXPR_SUBLINK:
			expr = (Expr *) lfirst(sublink->oper);
			strcat(buf, get_opname(((Oper *) (expr->oper))->opno));
			strcat(buf, " ");
			break;

		default:
			elog(ERROR, "unupported sublink type %d",
				 sublink->subLinkType);
			break;
	}

	strcat(buf, "(");
	strcat(buf, get_query_def(query, qh));
	strcat(buf, "))");

	return pstrdup(buf);
}


/* ----------
 * get_relation_name			- Get a relation name by Oid
 * ----------
 */
static char *
get_relation_name(Oid relid)
{
	HeapTuple	classtup;
	Form_pg_class classStruct;

	classtup = SearchSysCacheTuple(RELOID,
								   ObjectIdGetDatum(relid), 0, 0, 0);
	if (!HeapTupleIsValid(classtup))
		elog(ERROR, "cache lookup of relation %u failed", relid);

	classStruct = (Form_pg_class) GETSTRUCT(classtup);
	return nameout(&(classStruct->relname));
}


/* ----------
 * get_attribute_name			- Get an attribute name by it's
 *					  relations Oid and it's attnum
 * ----------
 */
static char *
get_attribute_name(Oid relid, int2 attnum)
{
	HeapTuple	atttup;
	Form_pg_attribute attStruct;

	atttup = SearchSysCacheTuple(ATTNUM,
						  ObjectIdGetDatum(relid), (Datum) attnum, 0, 0);
	if (!HeapTupleIsValid(atttup))
		elog(ERROR, "cache lookup of attribute %d in relation %u failed",
			 attnum, relid);

	attStruct = (Form_pg_attribute) GETSTRUCT(atttup);
	return nameout(&(attStruct->attname));
}


/* ----------
 * check_if_rte_used
 *		Check a targetlist or qual to see if a given rangetable entry
 *		is used in it
 * ----------
 */
static bool
check_if_rte_used(Node *node, Index rt_index, int levelsup)
{
	check_if_rte_used_context context;

	context.rt_index = rt_index;
	context.levelsup = levelsup;
	return check_if_rte_used_walker(node, &context);
}

static bool
check_if_rte_used_walker(Node *node,
						 check_if_rte_used_context *context)
{
	if (node == NULL)
		return false;
	if (IsA(node, Var))
	{
		Var		   *var = (Var *) node;

		return var->varno == context->rt_index &&
			var->varlevelsup == context->levelsup;
	}
	if (IsA(node, SubLink))
	{
		SubLink    *sublink = (SubLink *) node;
		Query	   *query = (Query *) sublink->subselect;

		/* Recurse into subquery; expression_tree_walker will not */
		if (check_if_rte_used((Node *) (query->targetList),
							  context->rt_index, context->levelsup + 1) ||
			check_if_rte_used(query->qual,
							  context->rt_index, context->levelsup + 1) ||
			check_if_rte_used(query->havingQual,
							  context->rt_index, context->levelsup + 1))
			return true;
		/* fall through to let expression_tree_walker examine lefthand args */
	}
	return expression_tree_walker(node, check_if_rte_used_walker,
								  (void *) context);
}