lmdb::key_iterator< K, V > Class Template Reference

#include <key_stream.h>

Collaboration diagram for lmdb::key_iterator< K, V >:

Public Types
using	value_type = std::pair<K, boost::iterator_range<value_iterator<V>>>
using	reference = value_type
using	pointer = void
using	difference_type = std::size_t
using	iterator_category = std::input_iterator_tag

Public Member Functions
	key_iterator () noexcept
	Construct an "end" iterator.
	key_iterator (MDB_cursor *cur)
bool	is_end () const noexcept
bool	equal (key_iterator const &rhs) const noexcept
key_iterator &	operator++ ()
key_iterator	operator++ (int)
value_type	operator* () const
K	get_key () const noexcept
template<typename T = V, typename F = T, std::size_t offset = 0>
value_iterator< T, F, offset >	make_value_iterator () const
template<typename T = V, typename F = T, std::size_t offset = 0>
boost::iterator_range< value_iterator< T, F, offset > >	make_value_range () const

Private Member Functions
void	increment ()

Private Attributes
MDB_cursor *	cur
epee::span< const std::uint8_t >	key

Detailed Description

template<typename K, typename V>
class lmdb::key_iterator< K, V >

An InputIterator for a fixed-sized LMDB key and value. operator++ iterates over keys.

Template Parameters

K	Key type in database records.
V	Value type in database records.

Note

This meets requirements for an InputIterator only. The iterator can only be incremented and dereferenced. All copies of an iterator share the same LMDB cursor, and therefore incrementing any copy will change the cursor state for all (incrementing an iterator will invalidate all prior copies of the iterator). Usage is identical to std::istream_iterator.

Member Typedef Documentation

difference_type

template<typename K, typename V>

using lmdb::key_iterator< K, V >::difference_type = std::size_t

iterator_category

template<typename K, typename V>

using lmdb::key_iterator< K, V >::iterator_category = std::input_iterator_tag

pointer

template<typename K, typename V>

using lmdb::key_iterator< K, V >::pointer = void

reference

template<typename K, typename V>

using lmdb::key_iterator< K, V >::reference = value_type

value_type

template<typename K, typename V>

using lmdb::key_iterator< K, V >::value_type = std::pair<K, boost::iterator_range<value_iterator<V>>>

Constructor & Destructor Documentation

key_iterator() [1/2]

template<typename K, typename V>

lmdb::key_iterator< K, V >::key_iterator ( )

inlinenoexcept

Construct an "end" iterator.

key_iterator() [2/2]

template<typename K, typename V>

lmdb::key_iterator< K, V >::key_iterator ( MDB_cursor * cur )

inline

Parameters

cur	Iterate over keys starting at this cursor position.

Exceptions

std::system_error

if unexpected LMDB error. This can happen if cur is invalid.

Member Function Documentation

equal()

template<typename K, typename V>

bool lmdb::key_iterator< K, V >::equal ( key_iterator< K, V > const & rhs ) const

inlinenoexcept

Returns

True iff rhs is referencing this key.

get_key()

template<typename K, typename V>

K lmdb::key_iterator< K, V >::get_key ( ) const

inlinenoexcept

Precondition

!is_end()

Returns

Current key

increment()

template<typename K, typename V>

void lmdb::key_iterator< K, V >::increment ( )

inlineprivate

is_end()

template<typename K, typename V>

bool lmdb::key_iterator< K, V >::is_end ( ) const

inlinenoexcept

Returns

True if this is one-past the last key.

make_value_iterator()

template<typename K, typename V>

template<typename T = V, typename F = T, std::size_t offset = 0>

value_iterator< T, F, offset > lmdb::key_iterator< K, V >::make_value_iterator ( ) const

inline

Return a C++ iterator over database values from current cursor position that will reach .is_end() after the last duplicate key record. Calling make_iterator() will return an iterator whose operator* will return an entire value (V). make_iterator<MONERO_FIELD(account, id)>() will return an iterator whose operator* will return a decltype(account.id) object - the other fields in the struct account are never copied from the database.

Exceptions

std::system_error

if LMDB has unexpected errors.

Returns

C++ iterator starting at current cursor position.

make_value_range()

template<typename K, typename V>

template<typename T = V, typename F = T, std::size_t offset = 0>

boost::iterator_range< value_iterator< T, F, offset > > lmdb::key_iterator< K, V >::make_value_range ( ) const

inline

Return a range from current cursor position until last duplicate key record. Useful in for-each range loops or in templated code expecting a range of elements. Calling make_range() will return a range of T objects. make_range<MONERO_FIELD(account, id)>() will return a range of decltype(account.id) objects - the other fields in the struct account are never copied from the database.

Exceptions

std::system_error

if LMDB has unexpected errors.

Returns

An InputIterator range over values at cursor position.

operator*()

template<typename K, typename V>

value_type lmdb::key_iterator< K, V >::operator* ( ) const

inline

Precondition

!is_end()

Returns

{current key, current value range}

operator++() [1/2]

template<typename K, typename V>

key_iterator & lmdb::key_iterator< K, V >::operator++ ( )

inline

Moves iterator to next key or end. Invalidates all prior copies of the iterator.

operator++() [2/2]

template<typename K, typename V>

key_iterator lmdb::key_iterator< K, V >::operator++ ( int )

inline

Moves iterator to next key or end.

Returns

A copy that is already invalidated, ignore

Member Data Documentation

cur

template<typename K, typename V>

MDB_cursor* lmdb::key_iterator< K, V >::cur

private

key

template<typename K, typename V>

epee::span<const std::uint8_t> lmdb::key_iterator< K, V >::key

private

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

• src/lmdb/key_stream.h