tkrzw::RemoteDBM::Iterator Class Reference

Iterator for each record. More...

#include <tkrzw_dbm_remote.h>

Public Member Functions
	~Iterator ()
	Destructor. More...
	Iterator (const Iterator &rhs)=delete
	Copy and assignment are disabled. More...
Iterator &	operator= (const Iterator &rhs)=delete
void	Cancel ()
	Cancels the current operation. More...
Status	First ()
	Initializes the iterator to indicate the first record. More...
Status	Last ()
	Initializes the iterator to indicate the last record. More...
Status	Jump (std::string_view key)
	Initializes the iterator to indicate a specific record. More...
Status	JumpLower (std::string_view key, bool inclusive=false)
	Initializes the iterator to indicate the last record whose key is lower than a given key. More...
Status	JumpUpper (std::string_view key, bool inclusive=false)
	Initializes the iterator to indicate the first record whose key is upper than a given key. More...
Status	Next ()
	Moves the iterator to the next record. More...
Status	Previous ()
	Moves the iterator to the previous record. More...
Status	Get (std::string *key=nullptr, std::string *value=nullptr)
	Gets the key and the value of the current record of the iterator. More...
std::string	GetKey (std::string_view default_value="")
	Gets the key of the current record, in a simple way. More...
std::string	GetValue (std::string_view default_value="")
	Gets the value of the current record, in a simple way. More...
Status	Set (std::string_view value)
	Sets the value of the current record. More...
Status	Remove ()
	Removes the current record. More...
Status	Step (std::string *key=nullptr, std::string *value=nullptr)
	Gets the current record and moves the iterator to the next record. More...

Friends
class	tkrzw::RemoteDBM

Detailed Description

Iterator for each record.

When the database is updated, some iterators may or may not be invalided. Operations with invalidated iterators fails gracefully with NOT_FOUND_ERROR.

An instance of this class dominates a thread on the server so you should destroy when it is no longer in use.

Constructor & Destructor Documentation

~Iterator()

tkrzw::RemoteDBM::Iterator::~Iterator

(

)

Destructor.

Iterator()

tkrzw::RemoteDBM::Iterator::Iterator ( const Iterator &  rhs )

explicitdelete

Copy and assignment are disabled.

Member Function Documentation

Cancel()

void tkrzw::RemoteDBM::Iterator::Cancel

(

)

Cancels the current operation.

This is called by another thread than the thread doing the operation.

First()

Status tkrzw::RemoteDBM::Iterator::First

(

)

Initializes the iterator to indicate the first record.

Returns

The result status.

Even if there's no record, the operation doesn't fail.

Last()

Status tkrzw::RemoteDBM::Iterator::Last

(

)

Initializes the iterator to indicate the last record.

Returns

The result status.

Even if there's no record, the operation doesn't fail. This method is suppoerted only by ordered databases.

Jump()

Status tkrzw::RemoteDBM::Iterator::Jump

(

std::string_view

key

)

Initializes the iterator to indicate a specific record.

Parameters

key	The key of the record to look for.

Returns

The result status.

Ordered databases can support "lower bound" jump; If there's no record with the same key, the iterator refers to the first record whose key is greater than the given key. The operation fails with unordered databases if there's no record with the same key.

JumpLower()

Status tkrzw::RemoteDBM::Iterator::JumpLower	(	std::string_view	key,
		bool	inclusive = false
	)

Initializes the iterator to indicate the last record whose key is lower than a given key.

Parameters

key	The key to compare with.
inclusive	If true, the condition is inclusive: equal to or lower than the key.

Returns

The result status.

Even if there's no matching record, the operation doesn't fail. This method is suppoerted only by ordered databases.

JumpUpper()

Status tkrzw::RemoteDBM::Iterator::JumpUpper	(	std::string_view	key,
		bool	inclusive = false
	)

Initializes the iterator to indicate the first record whose key is upper than a given key.

Parameters

key	The key to compare with.
inclusive	If true, the condition is inclusive: equal to or upper than the key.

Returns

The result status.

Even if there's no matching record, the operation doesn't fail. This method is suppoerted only by ordered databases.

Next()

Status tkrzw::RemoteDBM::Iterator::Next

(

)

Moves the iterator to the next record.

Returns

The result status.

If the current record is missing, the operation fails. Even if there's no next record, the operation doesn't fail.

Previous()

Status tkrzw::RemoteDBM::Iterator::Previous

(

)

Moves the iterator to the previous record.

Returns

The result status.

If the current record is missing, the operation fails. Even if there's no previous record, the operation doesn't fail. This method is suppoerted only by ordered databases.

Get()

Status tkrzw::RemoteDBM::Iterator::Get	(	std::string *	key = nullptr,
		std::string *	value = nullptr
	)

Gets the key and the value of the current record of the iterator.

Parameters

key	The pointer to a string object to contain the record key. If it is nullptr, the key data is ignored.
value	The pointer to a string object to contain the record value. If it is nullptr, the value data is ignored.

Returns

The result status.

GetKey()

std::string tkrzw::RemoteDBM::Iterator::GetKey

(

std::string_view

default_value = ""

)

Gets the key of the current record, in a simple way.

Parameters

default_value

The value to be returned on failure.

Returns

The key of the current record on success, or the default value on failure.

GetValue()

std::string tkrzw::RemoteDBM::Iterator::GetValue

(

std::string_view

default_value = ""

)

Gets the value of the current record, in a simple way.

Parameters

default_value

The value to be returned on failure.

Returns

The value of the current record on success, or the default value on failure.

Set()

Status tkrzw::RemoteDBM::Iterator::Set

(

std::string_view

value

)

Sets the value of the current record.

Parameters

value

The value of the record.

Returns

The result status.

Remove()

Status tkrzw::RemoteDBM::Iterator::Remove

(

)

Removes the current record.

Returns

The result status.

If possible, the iterator moves to the next record.

Step()

Status tkrzw::RemoteDBM::Iterator::Step	(	std::string *	key = nullptr,
		std::string *	value = nullptr
	)

Gets the current record and moves the iterator to the next record.

Parameters

key	The pointer to a string object to contain the record key. If it is nullptr, the key data is ignored.
value	The pointer to a string object to contain the record value. If it is nullptr, the value data is ignored.

Returns

The result status.