A keyset holds together a set of keys. More...

#include <keyset.hpp>

Public Member Functions
	KeySet ()

	KeySet (ckdb::KeySet *k)
	KeySet (const KeySet &other)
	KeySet (size_t alloc, va_list ap)
	Create a new keyset.
	KeySet (size_t alloc,...)
	Create a new keyset.
	~KeySet ()
	Deconstruct a keyset.
ckdb::KeySet *	release ()
ckdb::KeySet *	getKeySet () const
	Passes out the raw keyset pointer.
void	setKeySet (ckdb::KeySet *k)
	Take ownership of passed keyset.
KeySet &	operator= (KeySet const &other)
ssize_t	size () const
	The size of the keyset.
ckdb::KeySet *	dup () const
	Duplicate a keyset.
void	copy (const KeySet &other)
	Copy a keyset.
void	clear ()
	Clear the keyset.
ssize_t	append (const Key &toAppend)
	append a key
ssize_t	append (const KeySet &toAppend)
	append a keyset
Key	head () const

Key	tail () const

void	rewind () const

Key	next () const

Key	current () const

void	setCursor (cursor_t cursor) const

cursor_t	getCursor () const

Key	pop ()

KeySet	cut (Key k)

Key	lookup (const Key &k, const option_t options=KDB_O_NONE) const

Key	lookup (std::string const &name, const option_t options=KDB_O_NONE) const
	Lookup a key by name.
Key	at (cursor_t pos) const
	Lookup a key by index.

Detailed Description

A keyset holds together a set of keys.

Methods to manipulate KeySets. A KeySet is a sorted set of keys. So the correct name actually would be KeyMap.With ksNew() you can create a new KeySet.You can add keys with ksAppendKey() in the keyset. Using ksAppend() you can append a whole keyset.

Note: Because the key is not copied, also the pointer to the current metadata keyNextMeta() will be shared.

ksGetSize() tells you the current size of the keyset.With ksRewind() and ksNext() you can navigate through the keyset. Don't expect any particular order, but it is assured that you will get every key of the set.KeySets have an internal cursor . This is used for ksLookup() and kdbSet().KeySet has a fundamental meaning inside elektra. It makes it possible to get and store many keys at once inside the database. In addition to that the class can be used as high level datastructure in applications. With ksLookupByName() it is possible to fetch easily specific keys out of the list of keys.You can easily create and iterate keys:

#include <kdb.h>
// create a new keyset with 3 keys
// with a hint that about 20 keys will be inside
KeySet *myConfig = ksNew(20,
        keyNew ("user/name1", 0),
        keyNew ("user/name2", 0),
        keyNew ("user/name3", 0),
        KS_END);
// append a key in the keyset
ksAppendKey(myConfig, keyNew("user/name4", 0));
Key *current;
ksRewind(myConfig);
while ((current=ksNext(myConfig))!=0)
{
        printf("Key name is %s.\n", keyName (current));
}
ksDel (myConfig); // delete keyset and all keys appended

Invariant: always holds an underlying elektra keyset.

Note: that the cursor is mutable, so it might be changed even in const functions as described.

Constructor & Destructor Documentation

kdb::KeySet::KeySet ( )

inline

Creates a new empty keyset with no keys

Allocate, initialize and return a new KeySet object.Objects created with ksNew() must be destroyed with ksDel().You can use a various long list of parameters to preload the keyset with a list of keys. Either your first and only parameter is 0 or your last parameter must be KEY_END.So, terminate with ksNew(0, KS_END) or ksNew(20, ..., KS_END)For most uses

KeySet *keys = ksNew(0, KS_END);
// work with it
ksDel (keys);

goes ok, the alloc size will be 16, defined in kdbprivate.h. The alloc size will be doubled whenever size reaches alloc size, so it also performs out large keysets.But if you have any clue how large your keyset may be you should read the next statements.If you want a keyset with length 15 (because you know of your application that you normally need about 12 up to 15 keys), use:

KeySet * keys = ksNew (15,
        keyNew ("user/sw/app/fixedConfiguration/key01", KEY_SWITCH_VALUE, "value01", 0),
        keyNew ("user/sw/app/fixedConfiguration/key02", KEY_SWITCH_VALUE, "value02", 0),
        keyNew ("user/sw/app/fixedConfiguration/key03", KEY_SWITCH_VALUE, "value03", 0),
        // ...
        keyNew ("user/sw/app/fixedConfiguration/key15", KEY_SWITCH_VALUE, "value15", 0),
        KS_END);
// work with it
ksDel (keys);

If you start having 3 keys, and your application needs approximately 200-500 keys, you can use:

KeySet * config = ksNew (500,
        keyNew ("user/sw/app/fixedConfiguration/key1", KEY_SWITCH_VALUE, "value1", 0),
        keyNew ("user/sw/app/fixedConfiguration/key2", KEY_SWITCH_VALUE, "value2", 0),
        keyNew ("user/sw/app/fixedConfiguration/key3", KEY_SWITCH_VALUE, "value3", 0),
        KS_END); // don't forget the KS_END at the end!
// work with it
ksDel (config);

Alloc size is 500, the size of the keyset will be 3 after ksNew. This means the keyset will reallocate when appending more than 497 keys.The main benefit of taking a list of variant length parameters is to be able to have one C-Statement for any possible KeySet.

Postcondition: the keyset is rewinded properly

See Also: ksDel() to free the KeySet afterwards; ksDup() to duplicate an existing KeySet

Parameters

alloc gives a hint for the size how many Keys may be stored initially

Returns: a ready to use KeySet object; 0 on memory error

kdb::KeySet::KeySet ( ckdb::KeySet * k )

inline

Takes ownership of keyset!

Keyset will be destroyed at destructor you cant continue to use keyset afterwards!

Use KeySet::release() to avoid destruction.

Parameters

k	the keyset to take the ownership from

See Also: release(); setKeySet()

kdb::KeySet::KeySet ( const KeySet & other )

inline

Duplicate a keyset.

This keyset will be a duplicate of the other afterwards.

Note: that they still reference to the same Keys, so if you change key values also the keys in the original keyset will be changed.

See Also: dup

kdb::KeySet::KeySet	(	size_t	alloc,
		va_list	ap
	)

inlineexplicit

Create a new keyset.

Parameters

alloc	minimum number of keys to allocate
ap	variable arguments list

Allocate, initialize and return a new KeySet object.Objects created with ksNew() must be destroyed with ksDel().You can use a various long list of parameters to preload the keyset with a list of keys. Either your first and only parameter is 0 or your last parameter must be KEY_END.So, terminate with ksNew(0, KS_END) or ksNew(20, ..., KS_END)For most uses

KeySet *keys = ksNew(0, KS_END);
// work with it
ksDel (keys);

goes ok, the alloc size will be 16, defined in kdbprivate.h. The alloc size will be doubled whenever size reaches alloc size, so it also performs out large keysets.But if you have any clue how large your keyset may be you should read the next statements.If you want a keyset with length 15 (because you know of your application that you normally need about 12 up to 15 keys), use:

KeySet * keys = ksNew (15,
        keyNew ("user/sw/app/fixedConfiguration/key01", KEY_SWITCH_VALUE, "value01", 0),
        keyNew ("user/sw/app/fixedConfiguration/key02", KEY_SWITCH_VALUE, "value02", 0),
        keyNew ("user/sw/app/fixedConfiguration/key03", KEY_SWITCH_VALUE, "value03", 0),
        // ...
        keyNew ("user/sw/app/fixedConfiguration/key15", KEY_SWITCH_VALUE, "value15", 0),
        KS_END);
// work with it
ksDel (keys);

If you start having 3 keys, and your application needs approximately 200-500 keys, you can use:

KeySet * config = ksNew (500,
        keyNew ("user/sw/app/fixedConfiguration/key1", KEY_SWITCH_VALUE, "value1", 0),
        keyNew ("user/sw/app/fixedConfiguration/key2", KEY_SWITCH_VALUE, "value2", 0),
        keyNew ("user/sw/app/fixedConfiguration/key3", KEY_SWITCH_VALUE, "value3", 0),
        KS_END); // don't forget the KS_END at the end!
// work with it
ksDel (config);

Alloc size is 500, the size of the keyset will be 3 after ksNew. This means the keyset will reallocate when appending more than 497 keys.The main benefit of taking a list of variant length parameters is to be able to have one C-Statement for any possible KeySet.

Postcondition: the keyset is rewinded properly

See Also: ksDel() to free the KeySet afterwards; ksDup() to duplicate an existing KeySet

Parameters

alloc gives a hint for the size how many Keys may be stored initially

Returns: a ready to use KeySet object; 0 on memory error

Precondition: caller must call va_start and va_end

va the list of arguments

Parameters

alloc	the allocation size
va	the list of variable arguments

kdb::KeySet::KeySet	(	size_t	alloc,
			...
	)

inlineexplicit

Create a new keyset.

Parameters

alloc	minimum number of keys to allocate
...	variable argument list

Allocate, initialize and return a new KeySet object.Objects created with ksNew() must be destroyed with ksDel().You can use a various long list of parameters to preload the keyset with a list of keys. Either your first and only parameter is 0 or your last parameter must be KEY_END.So, terminate with ksNew(0, KS_END) or ksNew(20, ..., KS_END)For most uses

KeySet *keys = ksNew(0, KS_END);
// work with it
ksDel (keys);

goes ok, the alloc size will be 16, defined in kdbprivate.h. The alloc size will be doubled whenever size reaches alloc size, so it also performs out large keysets.But if you have any clue how large your keyset may be you should read the next statements.If you want a keyset with length 15 (because you know of your application that you normally need about 12 up to 15 keys), use:

KeySet * keys = ksNew (15,
        keyNew ("user/sw/app/fixedConfiguration/key01", KEY_SWITCH_VALUE, "value01", 0),
        keyNew ("user/sw/app/fixedConfiguration/key02", KEY_SWITCH_VALUE, "value02", 0),
        keyNew ("user/sw/app/fixedConfiguration/key03", KEY_SWITCH_VALUE, "value03", 0),
        // ...
        keyNew ("user/sw/app/fixedConfiguration/key15", KEY_SWITCH_VALUE, "value15", 0),
        KS_END);
// work with it
ksDel (keys);

If you start having 3 keys, and your application needs approximately 200-500 keys, you can use:

KeySet * config = ksNew (500,
        keyNew ("user/sw/app/fixedConfiguration/key1", KEY_SWITCH_VALUE, "value1", 0),
        keyNew ("user/sw/app/fixedConfiguration/key2", KEY_SWITCH_VALUE, "value2", 0),
        keyNew ("user/sw/app/fixedConfiguration/key3", KEY_SWITCH_VALUE, "value3", 0),
        KS_END); // don't forget the KS_END at the end!
// work with it
ksDel (config);

Alloc size is 500, the size of the keyset will be 3 after ksNew. This means the keyset will reallocate when appending more than 497 keys.The main benefit of taking a list of variant length parameters is to be able to have one C-Statement for any possible KeySet.

Postcondition: the keyset is rewinded properly

See Also: ksDel() to free the KeySet afterwards; ksDup() to duplicate an existing KeySet

Parameters

alloc gives a hint for the size how many Keys may be stored initially

Returns: a ready to use KeySet object; 0 on memory error

Precondition: caller must call va_start and va_end

va the list of arguments

Parameters

alloc	the allocation size
va	the list of variable arguments

kdb::KeySet::~KeySet ( )

inline

Deconstruct a keyset.

A destructor for KeySet objects.Cleans all internal dynamic attributes, decrement all reference pointers to all keys and then keyDel() all contained Keys, and free()s the release the KeySet object memory (that was previously allocated by ksNew()).

Parameters

ks	the keyset object to work with

Returns: 0 when the keyset was freed; -1 on null pointer

See Also: ksNew()

Member Function Documentation

ssize_t kdb::KeySet::append ( const Key & toAppend )

inline

append a key

Parameters

toAppend key to append

Returns: number of keys in the keyset

Appends a Key to the end of ks.A pointer to the key will be stored, and not a private copy. So a future ksDel() on ks may keyDel() the toAppend object, see keyGetRef().The reference counter of the key will be incremented, and thus toAppend is not const.

Note: Because the key is not copied, also the pointer to the current metadata keyNextMeta() will be shared.

If the keyname already existed, it will be replaced with the new key.The KeySet internal cursor will be set to the new key.It is save to use ksAppendKey(ks, keyNew(..)).

Returns: the size of the KeySet after insertion; -1 on NULL pointers; -1 if insertion failed, the key will be deleted then.

Parameters

ks	KeySet that will receive the key
toAppend	Key that will be appended to ks or deleted

See Also: ksAppend(), keyNew(), ksDel(); keyIncRef()

ssize_t kdb::KeySet::append ( const KeySet & toAppend )

inline

append a keyset

Parameters

toAppend keyset to append

Returns: number of keys in the keyset

Append all toAppend contained keys to the end of the ks.toAppend KeySet will be left unchanged.If a key is both in toAppend and ks, the Key in ks will be overridden.

Note: Because the key is not copied, also the pointer to the current metadata keyNextMeta() will be shared.

Postcondition: Sorted KeySet ks with all keys it had before and additionally the keys from toAppend

Returns: the size of the KeySet after transfer; -1 on NULL pointers

Parameters

ks	the KeySet that will receive the keys
toAppend	the KeySet that provides the keys that will be transferred

See Also: ksAppendKey()

Key kdb::KeySet::at ( cursor_t pos ) const

inline

Lookup a key by index.

Parameters

pos	cursor position

Returns: the found key

void kdb::KeySet::clear ( )

inline

Clear the keyset.

Keyset will have no keys afterwards.

void kdb::KeySet::copy ( const KeySet & other )

inline

Copy a keyset.

Parameters

other other keyset to copy

Copy a keyset.Most often you may want a duplicate of a keyset, see ksDup() or append keys, see ksAppend(). But in some situations you need to copy a keyset to a existing keyset, for that this function exists.You can also use it to clear a keyset when you pass a NULL pointer as source.Note that all keys in dest will be deleted. Afterwards the content of the source will be added to the destination and the ksCurrent() is set properly in dest.A flat copy is made, so the keys will not be duplicated, but there reference counter is updated, so both keysets need to be ksDel().

Note: Because the key is not copied, also the pointer to the current metadata keyNextMeta() will be shared.

int f (KeySet *ks)
{
        KeySet *c = ksNew (20, ..., KS_END);
        // c receives keys
        ksCopy (ks, c); // pass the keyset to the caller
        ksDel (c);
}       // caller needs to ksDel (ks)

Parameters

source	has to be an initialized source KeySet or NULL
dest	has to be an initialized KeySet where to write the keys

Returns: 1 on success; 0 if dest was cleared successfully (source is NULL); -1 on NULL pointer

See Also: ksNew(), ksDel(), ksDup(); keyCopy() for copying keys

Key kdb::KeySet::current ( ) const

inline

Return the current Key.The pointer is NULL if you reached the end or after ksRewind().

Note: You must not delete the key or change the key, use ksPop() if you want to delete it.

Parameters

ks	the keyset object to work with

Returns: pointer to the Key pointed by ks's cursor; 0 on NULL pointer

See Also: ksNext(), ksRewind()

KeySet kdb::KeySet::cut ( Key k )

inline

Cuts out a keyset at the cutpoint.Searches for the cutpoint inside the KeySet ks. If found it cuts out everything which is below (see keyIsBelow()) this key. These keys will be missing in the keyset ks. Instead, they will be moved to the returned keyset. If cutpoint is not found an empty keyset is returned and ks is not changed.The cursor will stay at the same key as it was before. If the cursor was inside the region of cut (moved) keys, the cursor will be set to the key before the cutpoint.If you use ksCut() on a keyset you got from kdbGet() and plan to make a kdbSet() later, make sure that you keep all keys that should not be removed permanently. You have to keep the KeySet that was returned and the KeySet ks.

Example:

You have the keyset ks:

system/mountpoint/interest
system/mountpoint/interest/folder
system/mountpoint/interest/folder/key1
system/mountpoint/interest/folder/key2
system/mountpoint/other/key1

When you use

        Key *parentKey = keyNew("system/mountpoint/interest", KEY_END);
        KDB *kdb = kdbOpen(parentKey);
        KeySet *ks = ksNew(0, KS_END);
        kdbGet(kdb, ks, parentKey);
        KeySet *returned = ksCut(ks, parentKey);
        kdbSet(kdb, ks, parentKey); // all keys below cutpoint are now removed
        kdbClose(kdb, parentKey);

Then in returned are:

system/mountpoint/interest
system/mountpoint/interest/folder
system/mountpoint/interest/folder/key1
system/mountpoint/interest/folder/key2

And in ks are:

system/mountpoint/other/key1

So kdbSet() permanently removes all keys below system/mountpoint/interest.

See Also: kdbGet() for explanation why you might get more keys than you requested.

Returns: a new allocated KeySet which needs to deleted with ksDel(). The keyset consists of all keys (of the original keyset ks) below the cutpoint. If the key cutpoint exists, it will also be appended.

Return values

0	on null pointers, no key name or allocation problems

Parameters

ks	the keyset to cut. It will be modified by removing all keys below the cutpoint. The cutpoint itself will also be removed.
cutpoint	the point where to cut out the keyset

ckdb::KeySet * kdb::KeySet::dup ( ) const

inline

Duplicate a keyset.

Returns: a copy of the keys

Return a duplicate of a keyset.Objects created with ksDup() must be destroyed with ksDel().Memory will be allocated as needed for dynamic properties, so you need to ksDel() the returned pointer.A flat copy is made, so the keys will not be duplicated, but there reference counter is updated, so both keysets need ksDel().

Parameters

source has to be an initialized source KeySet

Returns: a flat copy of source on success; 0 on NULL pointer

See Also: ksNew(), ksDel(); keyDup() for Key duplication

cursor_t kdb::KeySet::getCursor ( ) const

inline

Get the KeySet internal cursor.Use it to get the cursor of the actual position.

Warning: Cursors are getting invalid when the key was ksPop()ed or ksLookup() with KDB_O_POP was used.

ckdb::KeySet * kdb::KeySet::getKeySet ( ) const

inline

Passes out the raw keyset pointer.

Returns: pointer to internal ckdb KeySet

See Also: release(); setKeySet()

Key kdb::KeySet::head ( ) const

inline

Returns: alphabetical first key

Return the first key in the KeySet.The KeySets cursor will not be effected.If ksCurrent()==ksHead() you know you are on the first key.

Parameters

ks	the keyset object to work with

Returns: the first Key of a keyset; 0 on NULL pointer or empty keyset

See Also: ksTail() for the last Key; ksRewind(), ksCurrent() and ksNext() for iterating over the KeySet

Key kdb::KeySet::lookup	(	const Key &	key,
		const option_t	options = `KDB_O_NONE`
	)		const

inline

Look for a Key contained in ks that matches the name of the key.

Note: That the internal key cursor will point to the found key

Key kdb::KeySet::lookup	(	std::string const &	name,
		const option_t	options = `KDB_O_NONE`
	)		const

inline

Lookup a key by name.

Parameters

name	the name to look for
options	some options to pass

Returns: the found key

See Also: lookup (const Key &Key, const option_t options)

Note: That the internal key cursor will point to the found key

Key kdb::KeySet::next ( ) const

inline

Returns the next Key in a KeySet.KeySets have an internal cursor that can be reset with ksRewind(). Every time ksNext() is called the cursor is incremented and the new current Key is returned.You'll get a NULL pointer if the key after the end of the KeySet was reached. On subsequent calls of ksNext() it will still return the NULL pointer.The ks internal cursor will be changed, so it is not const.

Note: You must not delete or change the key, use ksPop() if you want to delete it.

Parameters

ks	the keyset object to work with

Returns: the new current Key; 0 when the end is reached; 0 on NULL pointer

See Also: ksRewind(), ksCurrent()

KeySet & kdb::KeySet::operator= ( KeySet const & other )

inline

Duplicate a keyset.

This keyset will be a duplicate of the other afterwards.

Note: that they still reference to the same Keys, so if you change key values also the keys in the original keyset will be changed.

Key kdb::KeySet::pop ( )

inline

Remove and return the last key of ks.The reference counter will be decremented by one.The KeySets cursor will not be effected if it did not point to the popped key.

Note: You need to keyDel() the key afterwards, if you don't append it to another keyset. It has the same semantics like a key allocated with keyNew() or keyDup().

ks1=ksNew(0, KS_END);
ks2=ksNew(0, KS_END);
k1=keyNew("user/name", KEY_END); // ref counter 0
ksAppendKey(ks1, k1); // ref counter 1
ksAppendKey(ks2, k1); // ref counter 2
k1=ksPop (ks1); // ref counter 1
k1=ksPop (ks2); // ref counter 0, like after keyNew()
ksAppendKey(ks1, k1); // ref counter 1
ksDel (ks1); // key is deleted too
ksDel (ks2);
 *

Returns: the last key of ks; NULL if ks is empty or on NULL pointer

Parameters

ks	KeySet to work with

See Also: ksAppendKey(), ksAppend(); commandList() for an example

ckdb::KeySet * kdb::KeySet::release ( )

inline

If you don't want destruction of keyset at the end you can release the pointer.

void kdb::KeySet::rewind ( ) const

inline

Rewinds the KeySet internal cursor.Use it to set the cursor to the beginning of the KeySet. ksCurrent() will then always return NULL afterwards. So you want to ksNext() first.

ksRewind (ks);

while ((key = ksNext (ks))!=0) {}

Parameters

ks	the keyset object to work with

Returns: 0 on success; -1 on NULL pointer

See Also: ksNext(), ksCurrent()

void kdb::KeySet::setCursor ( cursor_t cursor ) const

inline

Set the KeySet internal cursor.Use it to set the cursor to a stored position. ksCurrent() will then be the position which you got with.

Warning: Cursors may get invalid when the key was ksPop()ed or ksLookup() was used together with KDB_O_POP.

cursor_t cursor;
..
// key now in any position here
cursor = ksGetCursor (ks);
while ((key = keyNextMeta (ks))!=0) {}
ksSetCursor (ks, cursor); // reset state
ksCurrent(ks); // in same position as before

An invalid cursor will set the keyset to its beginning like ksRewind(). When you set an invalid cursor ksCurrent() is 0 and ksNext() == ksHead().

Parameters

cursor	the cursor to use
ks	the keyset object to work with

Returns: 0 when the keyset is ksRewind()ed; 1 otherwise; -1 on NULL pointer

See Also: ksNext(), ksGetCursor()

void kdb::KeySet::setKeySet ( ckdb::KeySet * k )

inline

Take ownership of passed keyset.

Parameters

k	the keyset to take ownership from

See Also: release(); getKeySet()

ssize_t kdb::KeySet::size ( ) const

inline

The size of the keyset.

Returns: the number of keys in the keyset

Key kdb::KeySet::tail ( ) const

inline

Returns: alphabetical last key

Return the last key in the KeySet.The KeySets cursor will not be effected.If ksCurrent()==ksTail() you know you are on the last key. ksNext() will return a NULL pointer afterwards.

Parameters

ks	the keyset object to work with

Returns: the last Key of a keyset; 0 on NULL pointer or empty keyset

See Also: ksHead() for the first Key; ksRewind(), ksCurrent() and ksNext() for iterating over the KeySet

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

keyset.hpp

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation