lmdb::cursor Class Reference

Resource class for MDB_cursor* handles. More...

#include <lmdb++.h>

Public Member Functions
	cursor (MDB_cursor *const handle) noexcept
	Constructor.
	cursor (cursor &&other) noexcept
	Move constructor.
cursor &	operator= (cursor &&other) noexcept
	Move assignment operator.
	~cursor () noexcept
	Destructor.
	operator MDB_cursor * () const noexcept
	Returns the underlying MDB_cursor* handle.
MDB_cursor *	handle () const noexcept
	Returns the underlying MDB_cursor* handle.
void	close () noexcept
	Closes this cursor.
void	renew (MDB_txn *const txn)
	Renews this cursor.
MDB_txn *	txn () const noexcept
	Returns the cursor's transaction handle.
MDB_dbi	dbi () const noexcept
	Returns the cursor's database handle.
bool	get (MDB_val *const key, const MDB_cursor_op op)
	Retrieves a key from the database.
bool	get (lmdb::val &key, const MDB_cursor_op op)
	Retrieves a key from the database.
bool	get (MDB_val *const key, MDB_val *const val, const MDB_cursor_op op)
	Retrieves a key/value pair from the database.
bool	get (lmdb::val &key, lmdb::val &val, const MDB_cursor_op op)
	Retrieves a key/value pair from the database.
bool	get (std::string &key, std::string &val, const MDB_cursor_op op)
	Retrieves a key/value pair from the database.
template<typename K>
bool	find (const K &key, const MDB_cursor_op op=MDB_SET)
	Positions this cursor at the given key.

Static Public Member Functions
static cursor	open (MDB_txn *const txn, const MDB_dbi dbi)
	Creates an LMDB cursor.

Static Public Attributes
static constexpr unsigned int	default_flags = 0

Protected Attributes
MDB_cursor *	_handle {nullptr}

Detailed Description

Resource class for MDB_cursor* handles.

Note

Instances of this class are movable, but not copyable.

See also

http://symas.com/mdb/doc/group__internal.html#structMDB__cursor

Constructor & Destructor Documentation

cursor() [1/2]

lmdb::cursor::cursor ( MDB_cursor *const handle )

inlinenoexcept

Constructor.

Parameters

handle

a valid MDB_cursor* handle

cursor() [2/2]

lmdb::cursor::cursor ( cursor && other )

inlinenoexcept

Move constructor.

~cursor()

lmdb::cursor::~cursor ( )

inlinenoexcept

Destructor.

Member Function Documentation

close()

void lmdb::cursor::close ( )

inlinenoexcept

Closes this cursor.

Note

this method is idempotent

Postcondition

handle() == nullptr

dbi()

MDB_dbi lmdb::cursor::dbi ( ) const

inlinenoexcept

Returns the cursor's database handle.

find()

template<typename K>

bool lmdb::cursor::find ( const K & key, const MDB_cursor_op op = MDB_SET )

inline

Positions this cursor at the given key.

Parameters

key
op

Exceptions

lmdb::error

on failure

get() [1/5]

bool lmdb::cursor::get ( lmdb::val & key, const MDB_cursor_op op )

inline

Retrieves a key from the database.

Parameters

key
op

Exceptions

lmdb::error

on failure

get() [2/5]

bool lmdb::cursor::get ( lmdb::val & key, lmdb::val & val, const MDB_cursor_op op )

inline

Retrieves a key/value pair from the database.

Parameters

key
val
op

Exceptions

lmdb::error

on failure

get() [3/5]

bool lmdb::cursor::get ( MDB_val *const key, const MDB_cursor_op op )

inline

Retrieves a key from the database.

Parameters

key
op

Exceptions

lmdb::error

on failure

get() [4/5]

bool lmdb::cursor::get ( MDB_val *const key, MDB_val *const val, const MDB_cursor_op op )

inline

Retrieves a key/value pair from the database.

Parameters

key
val	(may be nullptr)
op

Exceptions

lmdb::error

on failure

get() [5/5]

bool lmdb::cursor::get ( std::string & key, std::string & val, const MDB_cursor_op op )

inline

Retrieves a key/value pair from the database.

Parameters

key
val
op

Exceptions

lmdb::error

on failure

handle()

MDB_cursor * lmdb::cursor::handle ( ) const

inlinenoexcept

Returns the underlying MDB_cursor* handle.

open()

cursor lmdb::cursor::open ( MDB_txn *const txn, const MDB_dbi dbi )

inlinestatic

Creates an LMDB cursor.

Parameters

txn	the transaction handle
dbi	the database handle

Exceptions

lmdb::error

on failure

operator MDB_cursor *()

lmdb::cursor::operator MDB_cursor * ( ) const

inlinenoexcept

Returns the underlying MDB_cursor* handle.

operator=()

cursor & lmdb::cursor::operator= ( cursor && other )

inlinenoexcept

Move assignment operator.

renew()

void lmdb::cursor::renew ( MDB_txn *const txn )

inline

Renews this cursor.

Parameters

txn	the transaction scope

Exceptions

lmdb::error

on failure

txn()

MDB_txn * lmdb::cursor::txn ( ) const

inlinenoexcept

Returns the cursor's transaction handle.

Member Data Documentation

_handle

MDB_cursor* lmdb::cursor::_handle {nullptr}

protected

default_flags

unsigned int lmdb::cursor::default_flags = 0

staticconstexpr

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The documentation for this class was generated from the following file:

• lmdb++.h