utils-lists 4.0.2
The µOS++ Intrusive Lists
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micro_os_plus::utils::double_list_links_base Class Reference

A base class for a doubly linked list node. More...

#include <micro-os-plus/utils/lists.h>

+ Inheritance diagram for micro_os_plus::utils::double_list_links_base:

Public Member Functions

constexpr double_list_links_base ()
 Construct an uninitialised list node.
 
 double_list_links_base (const double_list_links_base &)=delete
 Deleted copy constructor.
 
 double_list_links_base (double_list_links_base &&)=delete
 Deleted move constructor.
 
constexpr ~double_list_links_base ()
 Destruct the node.
 
constexpr void initialize (void)
 Initialise the node links.
 
void initialize_once (void)
 Initialise the node links only if not already initialised.
 
void link_next (double_list_links_base *node)
 Link the new node as next.
 
void link_previous (double_list_links_base *node)
 Link the new node as previous.
 
bool linked (void) const
 Check if the node is linked to a doubly linked list.
 
constexpr double_list_links_basenext (void) const
 Get the link to the next node.
 
double_list_links_baseoperator= (const double_list_links_base &)=delete
 Deleted copy assignment operator.
 
double_list_links_baseoperator= (double_list_links_base &&)=delete
 Deleted move assignment operator.
 
constexpr double_list_links_baseprevious (void) const
 Get the link to the previous node.
 
bool uninitialized (void) const
 Check if the node is uninitialised.
 
void unlink (void)
 Remove this node from the list.
 

Protected Attributes

double_list_links_basenext_
 Pointer to the next node.
 
double_list_links_baseprevious_
 Pointer to the previous node.
 

Detailed Description

A base class for a doubly linked list node.

This class provides a pair of uninitialised pointers to the next and previous elements in a doubly linked list, along with a set of simple (some inlined) methods to access and manipulate these pointers.

Note
Both regular and statically allocated list elements are derived from this class.

Definition at line 112 of file lists.h.

Constructor & Destructor Documentation

◆ double_list_links_base() [1/3]

micro_os_plus::utils::double_list_links_base::double_list_links_base ( )
constexpr

Construct an uninitialised list node.

This must be an empty constructor that does not modify the member pointers, leaving them unchanged. For statically initialised lists, this means both pointers remain as nullptr, representing an uninitialised state. For regular (dynamically initialised) lists, the derived class constructor will handle the initialisation of the pointers.

Note
This design allows statically allocated objects to be safely zero-initialised at startup (via BSS initialisation), ensuring that the list links are in a known state before any constructors run. It also avoids unnecessary writes for statically allocated objects.
Warning
Code analysis tools may report:
  • Member previous_ was not initialized in constructor
  • Member next_ was not initialized in constructor These warnings are expected and can be safely ignored in this context.
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.

Definition at line 75 of file lists-inlines.h.

◆ double_list_links_base() [2/3]

micro_os_plus::utils::double_list_links_base::double_list_links_base ( const double_list_links_base & )
delete

Deleted copy constructor.

Copying of list node objects is explicitly disallowed to prevent accidental duplication, which could compromise the integrity of the list structure.

◆ double_list_links_base() [3/3]

micro_os_plus::utils::double_list_links_base::double_list_links_base ( double_list_links_base && )
delete

Deleted move constructor.

Moving of list node objects is explicitly disallowed to avoid invalid or inconsistent links within the list that could result from moving nodes.

◆ ~double_list_links_base()

micro_os_plus::utils::double_list_links_base::~double_list_links_base ( )
constexpr

Destruct the node.

This must be an empty destructor that does not modify or reset the member pointers, leaving them unchanged. For both statically and dynamically allocated lists, the destructor does not perform any cleanup or pointer manipulation, as the list management is handled elsewhere.

Note
This design avoids unnecessary writes or side effects during object destruction, which is especially important for statically allocated objects or when list nodes may be reused or re-initialised after destruction.

Definition at line 93 of file lists-inlines.h.

Member Function Documentation

◆ initialize()

void micro_os_plus::utils::double_list_links_base::initialize ( void )
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.

Note
After unlinking a node from a list, it must be returned to this state to prevent accidental access through stale links.

Definition at line 113 of file lists-inlines.h.

◆ initialize_once()

void micro_os_plus::utils::double_list_links_base::initialize_once ( void )

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.

Note
This method must be manually called for a statically allocated list before inserting elements or performing any other operations.

Definition at line 83 of file lists.cpp.

◆ link_next()

void micro_os_plus::utils::double_list_links_base::link_next ( double_list_links_base * node)

Link the new node as next.

Parameters
[in]nodePointer 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.

Definition at line 101 of file lists.cpp.

◆ link_previous()

void micro_os_plus::utils::double_list_links_base::link_previous ( double_list_links_base * node)

Link the new node as previous.

Parameters
[in]nodePointer 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.

Definition at line 127 of file lists.cpp.

◆ linked()

bool micro_os_plus::utils::double_list_links_base::linked ( void ) const

Check if the node is linked to a doubly linked list.

Parameters
None.
Return values
trueThe node is linked with both pointers.
falseThe 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.

Definition at line 176 of file lists.cpp.

◆ next()

double_list_links_base * micro_os_plus::utils::double_list_links_base::next ( void ) const
constexpr

Get the link to the next node.

Parameters
None.
Return values
Pointerto 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.

Note
The returned pointer is of type double_list_links_base* and may need to be cast to the appropriate derived type by the caller.

Definition at line 137 of file lists-inlines.h.

◆ operator=() [1/2]

double_list_links_base & micro_os_plus::utils::double_list_links_base::operator= ( const double_list_links_base & )
delete

Deleted copy assignment operator.

Copy assignment is explicitly disallowed to prevent accidental overwriting of list node objects, which could lead to corruption of the list structure.

◆ operator=() [2/2]

double_list_links_base & micro_os_plus::utils::double_list_links_base::operator= ( double_list_links_base && )
delete

Deleted move assignment operator.

Move assignment is explicitly disallowed to avoid invalid or inconsistent links within the list that could result from moving nodes.

◆ previous()

double_list_links_base * micro_os_plus::utils::double_list_links_base::previous ( void ) const
constexpr

Get the link to the previous node.

Parameters
None.
Return values
Pointerto 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.

Note
The returned pointer is of type double_list_links_base* and may need to be cast to the appropriate derived type by the caller.

Definition at line 154 of file lists-inlines.h.

◆ uninitialized()

bool micro_os_plus::utils::double_list_links_base::uninitialized ( void ) const

Check if the node is uninitialised.

Parameters
None.
Return values
trueThe links are not initialised.
falseThe 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.

Definition at line 58 of file lists.cpp.

◆ unlink()

void micro_os_plus::utils::double_list_links_base::unlink ( void )

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.

Definition at line 151 of file lists.cpp.

Member Data Documentation

◆ next_

double_list_links_base* micro_os_plus::utils::double_list_links_base::next_
protected

Pointer to the next node.

Definition at line 273 of file lists.h.

◆ previous_

double_list_links_base* micro_os_plus::utils::double_list_links_base::previous_
protected

Pointer to the previous node.

Definition at line 268 of file lists.h.


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