dbms: improvement [#METR-13153].

dbms/include/DB/Functions/FunctionsStringSearch.h

@@ -211,7 +211,7 @@ inline bool likePatternIsStrstr(const String & pattern, String & res)
 {
 	res = "";
 
-	if (pattern.size() < 2 || *pattern.begin() != '%' || *pattern.rbegin() != '%')
+	if (pattern.size() < 2 || pattern.front() != '%' || pattern.back() != '%')
 		return false;
 
 	res.reserve(pattern.size() * 2);

dbms/src/Storages/MergeTree/MergeTreePartChecker.cpp

@@ -249,7 +249,7 @@ static size_t checkColumn(const String & path, const String & name, DataTypePtr
 void MergeTreePartChecker::checkDataPart(String path, const Settings & settings, const DataTypeFactory & data_type_factory,
 										 MergeTreeData::DataPart::Checksums * out_checksums)
 {
-	if (!path.empty() && *path.rbegin() != '/')
+	if (!path.empty() && path.back() != '/')
 		path += "/";
 
 	NamesAndTypesList columns;

dbms/src/Storages/StorageReplicatedMergeTree.cpp

@@ -66,8 +66,8 @@ StorageReplicatedMergeTree::StorageReplicatedMergeTree(
 	log(&Logger::get(database_name_ + "." + table_name + " (StorageReplicatedMergeTree)")),
 	shutdown_event(false)
 {
-	if (!zookeeper_path.empty() && *zookeeper_path.rbegin() == '/')
-		zookeeper_path.erase(zookeeper_path.end() - 1);
+	if (!zookeeper_path.empty() && zookeeper_path.back() == '/')
+		zookeeper_path.resize(zookeeper_path.size() - 1);
 	replica_path = zookeeper_path + "/replicas/" + replica_name;
 
 	bool skip_sanity_checks = false;
@@ -2837,8 +2837,8 @@ void StorageReplicatedMergeTree::getStatus(Status & res, bool with_zk_fields)
 void StorageReplicatedMergeTree::fetchPartition(const Field & partition, bool unreplicated, const String & from_)
 {
 	String from = from_;
-	if (*from.rbegin() == '/')
-		from.erase(from.end() - 1);
+	if (from.back() == '/')
+		from.resize(from.size() - 1);
 
     if (unreplicated)
 		throw Exception("Not implemented", ErrorCodes::NOT_IMPLEMENTED);	/// TODO