ruleutils.c

来自「PostgreSQL7.4.6 for Linux」· C语言 代码 · 共 2,475 行 · 第 1/5 页

	{
		appendContextKeyword(context, " HAVING ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 0);
		get_rule_expr(query->havingQual, context, false);
	}
}

static void
get_setop_query(Node *setOp, Query *query, deparse_context *context,
				TupleDesc resultDesc)
{
	StringInfo	buf = context->buf;
	bool		need_paren;

	if (IsA(setOp, RangeTblRef))
	{
		RangeTblRef *rtr = (RangeTblRef *) setOp;
		RangeTblEntry *rte = rt_fetch(rtr->rtindex, query->rtable);
		Query	   *subquery = rte->subquery;

		Assert(subquery != NULL);
		Assert(subquery->setOperations == NULL);
		/* Need parens if ORDER BY, FOR UPDATE, or LIMIT; see gram.y */
		need_paren = (subquery->sortClause ||
					  subquery->rowMarks ||
					  subquery->limitOffset ||
					  subquery->limitCount);
		if (need_paren)
			appendStringInfoChar(buf, '(');
		get_query_def(subquery, buf, context->namespaces, resultDesc,
					  context->prettyFlags, context->indentLevel);
		if (need_paren)
			appendStringInfoChar(buf, ')');
	}
	else if (IsA(setOp, SetOperationStmt))
	{
		SetOperationStmt *op = (SetOperationStmt *) setOp;

		/*
		 * We force parens whenever nesting two SetOperationStmts.
		 * There are some cases in which parens are needed around a leaf
		 * query too, but those are more easily handled at the next level
		 * down (see code above).
		 */
		need_paren = !IsA(op->larg, RangeTblRef);

		if (need_paren)
			appendStringInfoChar(buf, '(');
		get_setop_query(op->larg, query, context, resultDesc);
		if (need_paren)
			appendStringInfoChar(buf, ')');

		if (!PRETTY_INDENT(context))
			appendStringInfoChar(buf, ' ');
		switch (op->op)
		{
			case SETOP_UNION:
				appendContextKeyword(context, "UNION ",
									 -PRETTYINDENT_STD, 0, 0);
				break;
			case SETOP_INTERSECT:
				appendContextKeyword(context, "INTERSECT ",
									 -PRETTYINDENT_STD, 0, 0);
				break;
			case SETOP_EXCEPT:
				appendContextKeyword(context, "EXCEPT ",
									 -PRETTYINDENT_STD, 0, 0);
				break;
			default:
				elog(ERROR, "unrecognized set op: %d",
					 (int) op->op);
		}
		if (op->all)
			appendStringInfo(buf, "ALL ");

		if (PRETTY_INDENT(context))
			appendStringInfoChar(buf, '\n');

		need_paren = !IsA(op->rarg, RangeTblRef);

		if (need_paren)
			appendStringInfoChar(buf, '(');
		get_setop_query(op->rarg, query, context, resultDesc);
		if (need_paren)
			appendStringInfoChar(buf, ')');
	}
	else
	{
		elog(ERROR, "unrecognized node type: %d",
			 (int) nodeTag(setOp));
	}
}

/*
 * Display a sort/group clause.
 *
 * Also returns the expression tree, so caller need not find it again.
 */
static Node *
get_rule_sortgroupclause(SortClause *srt, List *tlist, bool force_colno,
						 deparse_context *context)
{
	StringInfo	buf = context->buf;
	TargetEntry *tle;
	Node	   *expr;

	tle = get_sortgroupclause_tle(srt, tlist);
	expr = (Node *) tle->expr;

	/*
	 * Use column-number form if requested by caller or if expression is a
	 * constant --- a constant is ambiguous (and will be misinterpreted by
	 * findTargetlistEntry()) if we dump it explicitly.
	 */
	if (force_colno || (expr && IsA(expr, Const)))
	{
		Assert(!tle->resdom->resjunk);
		appendStringInfo(buf, "%d", tle->resdom->resno);
	}
	else
		get_rule_expr(expr, context, true);

	return expr;
}

/* ----------
 * get_insert_query_def			- Parse back an INSERT parsetree
 * ----------
 */
static void
get_insert_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;
	RangeTblEntry *select_rte = NULL;
	RangeTblEntry *rte;
	char	   *sep;
	List	   *l;

	/*
	 * If it's an INSERT ... SELECT there will be a single subquery RTE
	 * for the SELECT.
	 */
	foreach(l, query->rtable)
	{
		rte = (RangeTblEntry *) lfirst(l);
		if (rte->rtekind != RTE_SUBQUERY)
			continue;
		if (select_rte)
			elog(ERROR, "too many RTEs in INSERT");
		select_rte = rte;
	}

	/*
	 * Start the query with INSERT INTO relname
	 */
	rte = rt_fetch(query->resultRelation, query->rtable);
	Assert(rte->rtekind == RTE_RELATION);

	if (PRETTY_INDENT(context))
	{
		context->indentLevel += PRETTYINDENT_STD;
		appendStringInfoChar(buf, ' ');
	}
	appendStringInfo(buf, "INSERT INTO %s",
					 generate_relation_name(rte->relid));

	/* Add the insert-column-names list */
	sep = " (";
	foreach(l, query->targetList)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);

		if (tle->resdom->resjunk)
			continue;			/* ignore junk entries */

		appendStringInfo(buf, sep);
		sep = ", ";
		appendStringInfo(buf, "%s",
						 quote_identifier(get_relid_attribute_name(rte->relid,
														tle->resdom->resno)));
	}
	appendStringInfo(buf, ") ");

	/* Add the VALUES or the SELECT */
	if (select_rte == NULL)
	{
		appendContextKeyword(context, "VALUES (",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
		sep = "";
		foreach(l, query->targetList)
		{
			TargetEntry *tle = (TargetEntry *) lfirst(l);

			if (tle->resdom->resjunk)
				continue;		/* ignore junk entries */

			appendStringInfo(buf, sep);
			sep = ", ";
			get_rule_expr((Node *) tle->expr, context, false);
		}
		appendStringInfoChar(buf, ')');
	}
	else
		get_query_def(select_rte->subquery, buf, NIL, NULL,
					  context->prettyFlags, context->indentLevel);
}


/* ----------
 * get_update_query_def			- Parse back an UPDATE parsetree
 * ----------
 */
static void
get_update_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;
	char	   *sep;
	RangeTblEntry *rte;
	List	   *l;

	/*
	 * Start the query with UPDATE relname SET
	 */
	rte = rt_fetch(query->resultRelation, query->rtable);
	Assert(rte->rtekind == RTE_RELATION);
	if (PRETTY_INDENT(context))
	{
		appendStringInfoChar(buf, ' ');
		context->indentLevel += PRETTYINDENT_STD;
	}
	appendStringInfo(buf, "UPDATE %s%s SET ",
					 only_marker(rte),
					 generate_relation_name(rte->relid));

	/* Add the comma separated list of 'attname = value' */
	sep = "";
	foreach(l, query->targetList)
	{
		TargetEntry *tle = (TargetEntry *) lfirst(l);

		if (tle->resdom->resjunk)
			continue;			/* ignore junk entries */

		appendStringInfo(buf, sep);
		sep = ", ";

		/*
		 * If the update expression is an array assignment, we mustn't put
		 * out "attname =" here; it will come out of the display of the
		 * ArrayRef node instead.
		 */
		if (!tleIsArrayAssign(tle))
			appendStringInfo(buf, "%s = ",
						quote_identifier(get_relid_attribute_name(rte->relid,
														tle->resdom->resno)));
		get_rule_expr((Node *) tle->expr, context, false);
	}

	/* Add the FROM clause if needed */
	get_from_clause(query, context);

	/* Finally add a WHERE clause if given */
	if (query->jointree->quals != NULL)
	{
		appendContextKeyword(context, " WHERE ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
		get_rule_expr(query->jointree->quals, context, false);
	}
}


/* ----------
 * get_delete_query_def			- Parse back a DELETE parsetree
 * ----------
 */
static void
get_delete_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;
	RangeTblEntry *rte;

	/*
	 * Start the query with DELETE FROM relname
	 */
	rte = rt_fetch(query->resultRelation, query->rtable);
	Assert(rte->rtekind == RTE_RELATION);
	if (PRETTY_INDENT(context))
	{
		context->indentLevel += PRETTYINDENT_STD;
		appendStringInfoChar(buf, ' ');
	}
	appendStringInfo(buf, "DELETE FROM %s%s",
					 only_marker(rte),
					 generate_relation_name(rte->relid));

	/* Add a WHERE clause if given */
	if (query->jointree->quals != NULL)
	{
		appendContextKeyword(context, " WHERE ",
							 -PRETTYINDENT_STD, PRETTYINDENT_STD, 1);
		get_rule_expr(query->jointree->quals, context, false);
	}
}


/* ----------
 * get_utility_query_def			- Parse back a UTILITY parsetree
 * ----------
 */
static void
get_utility_query_def(Query *query, deparse_context *context)
{
	StringInfo	buf = context->buf;

	if (query->utilityStmt && IsA(query->utilityStmt, NotifyStmt))
	{
		NotifyStmt *stmt = (NotifyStmt *) query->utilityStmt;

		appendContextKeyword(context, "",
							 0, PRETTYINDENT_STD, 1);
		appendStringInfo(buf, "NOTIFY %s",
				   quote_qualified_identifier(stmt->relation->schemaname,
											  stmt->relation->relname));
	}
	else
	{
		/* Currently only NOTIFY utility commands can appear in rules */
		elog(ERROR, "unexpected utility statement type");
	}
}


/*
 * Get the schemaname, refname and attname for a (possibly nonlocal) Var.
 *
 * schemaname is usually returned as NULL.	It will be non-null only if
 * use of the unqualified refname would find the wrong RTE.
 *
 * refname will be returned as NULL if the Var references an unnamed join.
 * In this case the Var *must* be displayed without any qualification.
 *
 * attname will be returned as NULL if the Var represents a whole tuple
 * of the relation.  (Typically we'd want to display the Var as "foo.*",
 * but it's convenient to return NULL to make it easier for callers to
 * distinguish this case.)
 */
static void
get_names_for_var(Var *var, deparse_context *context,
				  char **schemaname, char **refname, char **attname)
{
	List	   *nslist = context->namespaces;
	int			sup = var->varlevelsup;
	deparse_namespace *dpns;
	RangeTblEntry *rte;

	/* Find appropriate nesting depth */
	while (sup-- > 0 && nslist != NIL)
		nslist = lnext(nslist);
	if (nslist == NIL)
		elog(ERROR, "bogus varlevelsup: %d", var->varlevelsup);
	dpns = (deparse_namespace *) lfirst(nslist);

	/* Find the relevant RTE */
	if (var->varno >= 1 && var->varno <= length(dpns->rtable))
		rte = rt_fetch(var->varno, dpns->rtable);
	else if (var->varno == dpns->outer_varno)
		rte = dpns->outer_rte;
	else if (var->varno == dpns->inner_varno)
		rte = dpns->inner_rte;
	else
		rte = NULL;
	if (rte == NULL)
		elog(ERROR, "bogus varno: %d", var->varno);

	/* Emit results */
	*schemaname = NULL;			/* default assumptions */
	*refname = rte->eref->aliasname;

	/* Exceptions occur only if the RTE is alias-less */
	if (rte->alias == NULL)
	{
		if (rte->rtekind == RTE_RELATION)
		{
			/*
			 * It's possible that use of the bare refname would find
			 * another more-closely-nested RTE, or be ambiguous, in which
			 * case we need to specify the schemaname to avoid these
			 * errors.
			 */
			if (find_rte_by_refname(rte->eref->aliasname, context) != rte)
				*schemaname =
					get_namespace_name(get_rel_namespace(rte->relid));
		}
		else if (rte->rtekind == RTE_JOIN)
		{
			/* Unnamed join has neither schemaname nor refname */
			*refname = NULL;
		}
	}

	if (var->varattno == InvalidAttrNumber)
		*attname = NULL;
	else
		*attname = get_rte_attribute_name(rte, var->varattno);
}

/*
 * find_rte_by_refname		- look up an RTE by refname in a deparse context
 *
 * Returns NULL if there is no matching RTE or the refname is ambiguous.
 *
 * NOTE: this code is not really correct since it does not take account of
 * the fact that not all the RTEs in a rangetable may be visible from the
 * point where a Var reference appears.  For the purposes we need, however,
 * the only consequence of a false match is that we might stick a schema
 * qualifier on a Var that doesn't really need it.  So it seems close
 * enough.
 */
static RangeTblEntry *
find_rte_by_refname(const char *refname, deparse_context *context)
{
	RangeTblEntry *result = NULL;
	List	   *nslist;

	foreach(nslist, context->namespaces)
	{
		deparse_namespace *dpns = (deparse_namespace *) lfirst(nslist);
		List	   *rtlist;

		foreach(rtlist, dpns->rtable)
		{
			RangeTblEntry *rte = (RangeTblEntry *) lfirst(rtlist);

			if (strcmp(rte->eref->aliasname, refname) == 0)
			{
				if (result)
					return NULL;	/* it's ambiguous */
				result = rte;
			}
		}
		if (dpns->outer_rte &&
			strcmp(dpns->outer_rte->eref->aliasname, refname) == 0)
		{
			if (result)
				return NULL;	/* it's ambiguous */
			result = dpns->outer_rte;
		}
		if (dpns->inner_rte &&
			strcmp(dpns->inner_rte->eref->aliasname, refname) == 0)
		{
			if (result)
				return NULL;	/* it's ambiguous */
			result = dpns->inner_rte;
		}
		if (result)
			break;
	}
	return result;
}


/*
 * get_simple_binary_op_name
 *
 * helper function for isSimpleNode
 * will return single char binary operator name, or NULL if it's not
 */
static const char *
get_simple_binary_op_name(OpExpr *expr)
{
	List	   *args = expr->args;

	if (length(args) == 2)
	{
		/* binary operator */
		Node	   *arg1 = (Node *) lfirst(args);
		Node	   *arg2 = (Node *) lsecond(args);
		const char *op;

		op = generate_operator_name(expr->opno, exprType(arg1), exprType(arg2));
		if (strlen(op) == 1)
			return op;
	}
	return NULL;
}


/*
 * isSimpleNode - check if given node is simple (doesn't need parenthesizing)
 *
 *	true   : simple in the context of parent node's type
 *	false  : not simple
 */
static bool
isSimpleNode(Node *n