The double_list_links Class Reference
A class for the core of a doubly linked list (pointers to neighbours). More...
Declaration
class micro_os_plus::utils::double_list_links;
Included Headers
#include <micro-os-plus/utils/lists.h>Base class
| class | double_list_links_base |
A base class for a doubly linked list node. More... | |
Public Member Typedefs Index
| using | is_statically_allocated = std::false_type |
Type indicating that the links node is not statically allocated. More... | |
Public Constructors Index
| constexpr | double_list_links () |
Construct a list node (initialise the pointers). More... | |
| double_list_links (const double_list_links &)=delete | |
Deleted copy constructor. More... | |
| double_list_links (double_list_links &&)=delete | |
Deleted move constructor. More... | |
Public Destructor Index
| constexpr | ~double_list_links () |
Destruct the node. More... | |
Public Member Functions Index
| constexpr void | initialize (void) |
Initialise the node links. More... | |
| void | initialize_once (void) |
Initialise the node links only if not already initialised. More... | |
| void | link_next (double_list_links_base *node) |
Link the new node as next. More... | |
| void | link_previous (double_list_links_base *node) |
Link the new node as previous. More... | |
| bool | linked (void) const |
Check if the node is linked to a doubly linked list. More... | |
| constexpr double_list_links_base * | next (void) const |
Get the link to the next node. More... | |
| double_list_links & | operator= (const double_list_links &)=delete |
Deleted copy assignment operator. More... | |
| double_list_links & | operator= (double_list_links &&)=delete |
Deleted move assignment operator. More... | |
| constexpr double_list_links_base * | previous (void) const |
Get the link to the previous node. More... | |
| bool | uninitialized (void) const |
Check if the node is uninitialised. More... | |
| void | unlink (void) |
Remove this node from the list. More... | |
Protected Member Attributes Index
| double_list_links_base * | next_ |
Pointer to the next node. More... | |
| double_list_links_base * | previous_ |
Pointer to the previous node. More... | |
Description
A class for the core of a doubly linked list (pointers to neighbours).
The double_list_links class provides the fundamental structure for a doubly linked list node, inheriting the pair of pointers to the next and previous elements and the associated access methods from double_list_links_base. The constructor initialises the pointers to form an empty list, where both pointers refer to the node itself.
This class is intended for use as the core linking mechanism within doubly linked lists, supporting efficient insertion and removal operations.
Definition at line 295 of file lists.h.
Public Constructors
double_list_links()
| constexpr |
Construct a list node (initialise the pointers).
The constructor for double_list_links is used for regular (non-static) list link nodes. It explicitly initialises the node by calling initialize(), which sets both the previous_ and next_ pointers to point to this node itself, marking it as unlinked and ready for use in a list. This ensures that dynamically allocated or automatic list nodes always start in a known, safe state, regardless of their memory contents prior to construction.
For statically allocated nodes, the constructor is intentionally left empty to allow BSS zero-initialisation. For dynamically allocated nodes, explicit initialisation is required to avoid undefined pointer values.
- The rule of five
The copy constructor, move constructor, copy assignment operator, and move assignment operator are explicitly deleted to prevent accidental copying or moving of intrusive_list objects. This ensures the integrity of the list structure, as duplicating or moving lists could result in invalid or inconsistent links within the list.
Declaration at line 307 of file lists.h, definition at line 254 of file lists-inlines.h.
double_list_links()
| delete |
double_list_links()
| delete |
Public Destructor
~double_list_links()
| constexpr |
Destruct the node.
Destroys the node. No special cleanup is required as the class does not manage resources.
Declaration at line 360 of file lists.h, definition at line 266 of file lists-inlines.h.
Public Member Functions
initialize()
| constexpr |
Initialise the node links.
- Parameters
None.
- Returns
Nothing.
Sets both the previous_ and next_ pointers to point to this node itself, marking the node as unlinked. This state is used to indicate that the node is not currently part of any list.
This method is called during initialisation and after a node is unlinked from a list, ensuring the node is in a safe, standalone state and cannot be traversed as part of a list.
After unlinking a node from a list, it must be returned to this state to prevent accidental access through stale links.
Declaration at line 189 of file lists.h, definition at line 113 of file lists-inlines.h.
initialize_once()
|
Initialise the node links only if not already initialised.
- Parameters
None.
- Returns
Nothing.
If the statically allocated list is still in the initial uninitialised state (with both pointers nullptr), this method initialises the list to the empty state, with both pointers pointing to itself.
For non-statically initialised lists, this method is ineffective, since the node is always initialised at construct time.
This method must be manually called for a statically allocated list before inserting elements or performing any other operations.
Declaration at line 200 of file lists.h, definition at line 83 of file lists.cpp.
link_next()
|
Link the new node as next.
- Parameters
[in] node Pointer to the node to be linked as next.
- Returns
Nothing.
Insert the new node between the next pointer and the node pointed by it. This operation is used by lists to link new nodes to the list head. The new node's previous_ pointer is set to the current node, and its next_ pointer is set to the current node's next_. The neighbouring nodes are updated to point to the new node, maintaining the integrity of the double-linked list.
Declaration at line 210 of file lists.h, definition at line 101 of file lists.cpp.
link_previous()
|
Link the new node as previous.
- Parameters
[in] node Pointer to the node to be linked as previous.
- Returns
Nothing.
Insert the new node between the previous pointer and the node pointed by it. Used by lists to link new nodes to the list tail. The new node's next_ pointer is set to the current node, and its previous_ pointer is set to the current node's previous_. The neighbouring nodes are updated to point to the new node, maintaining the integrity of the double-linked list.
Declaration at line 220 of file lists.h, definition at line 127 of file lists.cpp.
linked()
|
Check if the node is linked to a doubly linked list.
- Parameters
None.
- Return Values
true The node is linked with both pointers. false The node is not linked.
To be linked, both pointers must point to different nodes than itself (double list requirement). If either next_ or previous_ points to this, the node is considered unlinked (empty state). This method checks the node's linkage status for safe list operations.
Declaration at line 242 of file lists.h, definition at line 176 of file lists.cpp.
next()
| constexpr |
Get the link to the next node.
- Parameters
None.
- Return Values
Pointer to the next node.
Returns a pointer to the next node in the list. If this node is the last in the list, the returned pointer may refer back to the list's sentinel node (for example, the links node in the list container) or to itself if the list is empty.
The returned pointer is of type double_list_links_base* and may need to be cast to the appropriate derived type by the caller.
Declaration at line 252 of file lists.h, definition at line 137 of file lists-inlines.h.
operator=()
| delete |
operator=()
| delete |
previous()
| constexpr |
Get the link to the previous node.
- Parameters
None.
- Return Values
Pointer to the previous node.
Returns a pointer to the previous node in the list. If this node is the first in the list, the returned pointer may refer back to the list's sentinel node (such as the links node in the list container) or to itself if the list is empty.
The returned pointer is of type double_list_links_base* and may need to be cast to the appropriate derived type by the caller.
Declaration at line 262 of file lists.h, definition at line 154 of file lists-inlines.h.
uninitialized()
|
Check if the node is uninitialised.
- Parameters
None.
- Return Values
true The links are not initialised. false The links are initialised.
An uninitialized node is a node with its pointers set to nullptr. Only statically allocated nodes in their initial state are considered uninitialized. Regular (dynamically or automatically allocated) nodes are always initialized during construction, so this method will only return true for statically allocated nodes that have not yet been initialized.
Declaration at line 178 of file lists.h, definition at line 58 of file lists.cpp.
unlink()
|
Remove this node from the list.
- Parameters
None.
- Returns
Nothing.
Update both neighbours to point to each other, effectively removing the node from the list. The node is then returned to the initial state (empty), with both pointers pointing to itself. This operation is safe to call even if the node is already unlinked.
Declaration at line 231 of file lists.h, definition at line 151 of file lists.cpp.
Protected Member Attributes
next_
| protected |
previous_
The documentation for this class was generated from the following files:
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