`doubly_list_links` Class

A class for the core of a doubly linked list (pointers to neighbours). More...

Declaration

class micro_os_plus::utils::doubly_list_links { ... }

Included Headers

Base class

class	doubly_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	doubly_list_links () noexcept
	Construct a list node (initialise the pointers). More...

	doubly_list_links (const doubly_list_links &)=delete
	Deleted copy constructor. More...

	doubly_list_links (doubly_list_links &&)=delete
	Deleted move constructor. More...

Public Destructor Index

constexpr	~doubly_list_links ()
	Destruct the node. More...

Public Operators Index

doubly_list_links &	operator= (const doubly_list_links &)=delete
	Deleted copy assignment operator. More...

doubly_list_links &	operator= (doubly_list_links &&)=delete
	Deleted move assignment operator. More...

Public Member Functions Index

constexpr void	initialise (void) noexcept
	Initialise the node links. More...

bool	initialise_once (void) noexcept
	Initialise the node links only if not already initialised. More...

bool	initialised (void) const noexcept
	Check if the node is initialised. More...

void	link_next (doubly_list_links_base *node) noexcept
	Link the new node as next. More...

void	link_previous (doubly_list_links_base *node) noexcept
	Link the new node as previous. More...

constexpr bool	linked (void) const noexcept
	Check if the node is linked to a doubly linked list. More...

constexpr doubly_list_links_base *	next (void) const noexcept
	Get the link to the next node. More...

constexpr doubly_list_links_base *	previous (void) const noexcept
	Get the link to the previous node. More...

void	unlink (void) noexcept
	Remove this node from the list. More...

Protected Member Attributes Index

doubly_list_links_base *	next_
	Pointer to the next node. More...

doubly_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 doubly_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 doubly_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 280 of file doubly-list-links.h.

Public Member Typedefs

is_statically_allocated

using micro_os_plus::utils::doubly_list_links::is_statically_allocated = std::false_type

Type indicating that the links node is not statically allocated.

Definition at line 287 of file doubly-list-links.h.

287 using is_statically_allocated = std::false_type;

Public Constructors

doubly_list_links()

micro_os_plus::utils::doubly_list_links::doubly_list_links ()

constexpr noexcept

Construct a list node (initialise the pointers).

The constructor for doubly_list_links is used for regular (non-static) list link nodes. It explicitly initialises the node by calling initialise(), 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.

info

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 doubly_list_links objects. This ensures the integrity of the list structure, as duplicating or moving nodes could result in invalid or inconsistent links within the list.

Declaration at line 292 of file doubly-list-links.h, definition at line 283 of file doubly-list-links-inlines.h.

283 constexpr doubly_list_links::doubly_list_links () noexcept

284 {

285 // For regular (non static) classes the members

286 // must be explicitly initialised.

287 initialise ();

288 }

Reference micro_os_plus::utils::doubly_list_links_base::initialise.

Referenced by doubly_list_links, doubly_list_links, operator= and operator=.

doubly_list_links()

micro_os_plus::utils::doubly_list_links::doubly_list_links (const doubly_list_links &)

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.

Definition at line 304 of file doubly-list-links.h.

Reference doubly_list_links.

doubly_list_links()

micro_os_plus::utils::doubly_list_links::doubly_list_links (doubly_list_links &&)

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.

Definition at line 313 of file doubly-list-links.h.

Reference doubly_list_links.

Public Destructor

~doubly_list_links()

micro_os_plus::utils::doubly_list_links::~doubly_list_links ()

constexpr

Destruct the node.

Destroys the node. No special cleanup is required as the class does not manage resources.

Declaration at line 345 of file doubly-list-links.h, definition at line 295 of file doubly-list-links-inlines.h.

295 constexpr doubly_list_links::~doubly_list_links ()

296 {

297 }

Public Operators

operator=()

doubly_list_links & micro_os_plus::utils::doubly_list_links::operator= (const doubly_list_links &)

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.

Definition at line 324 of file doubly-list-links.h.

Reference doubly_list_links.

operator=()

doubly_list_links & micro_os_plus::utils::doubly_list_links::operator= (doubly_list_links &&)

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.

Definition at line 335 of file doubly-list-links.h.

Reference doubly_list_links.

Public Member Functions

initialise()

void micro_os_plus::utils::doubly_list_links_base::initialise (void)

constexpr noexcept

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.

info

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

Declaration at line 174 of file doubly-list-links.h, definition at line 120 of file doubly-list-links-inlines.h.

120 doubly_list_links_base::initialise (void) noexcept

121 {

122 previous_ = this;

123 next_ = this;

124 }

References micro_os_plus::utils::doubly_list_links_base::next_ and micro_os_plus::utils::doubly_list_links_base::previous_.

Referenced by doubly_list_links, micro_os_plus::utils::doubly_list_links_base::initialise_once and micro_os_plus::utils::doubly_list_links_base::unlink.

initialise_once()

bool micro_os_plus::utils::doubly_list_links_base::initialise_once (void)

noexcept

Initialise the node links only if not already initialised.

Parameters: None.

Returns: true if the node was initialised, false otherwise.

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.

info

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

Declaration at line 185 of file doubly-list-links.h, definition at line 81 of file doubly-list-links.cpp.

81 doubly_list_links_base::initialise_once (void) noexcept

82 {

83 if (!initialised ())

84 {

85 initialise ();

86 return true;

87 }

88 return false;

89 }

References micro_os_plus::utils::doubly_list_links_base::initialise and micro_os_plus::utils::doubly_list_links_base::initialised.

initialised()

bool micro_os_plus::utils::doubly_list_links_base::initialised (void)

nodiscard noexcept

Check if the node is initialised.

Parameters: None.

Return Values

true	The links are initialised.
false	The links are not initialised.

An uninitialised node is a node with its pointers set to nullptr. Only statically allocated nodes in their initial state are considered uninitialised. Regular (dynamically or automatically allocated) nodes are always initialised during construction, so this method will only return false for statically allocated nodes that have not yet been initialised.

Declaration at line 163 of file doubly-list-links.h, definition at line 56 of file doubly-list-links.cpp.

56 doubly_list_links_base::initialised (void) const noexcept

57 {

58 if (previous_ == nullptr || next_ == nullptr)

59 {

60 assert (previous_ == nullptr);

61 assert (next_ == nullptr);

62 return false;

63 }

64 return true;

65 }

References micro_os_plus::utils::doubly_list_links_base::next_ and micro_os_plus::utils::doubly_list_links_base::previous_.

Referenced by micro_os_plus::utils::doubly_list_links_base::initialise_once.

link_next()

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

noexcept

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 doubly-linked list.

Declaration at line 195 of file doubly-list-links.h, definition at line 101 of file doubly-list-links.cpp.

101 doubly_list_links_base::link_next (doubly_list_links_base* node) noexcept

102 {

103#if defined(MICRO_OS_PLUS_UTILS_LISTS_TRACE_ENABLED)

104 trace::printf ("%s() link %p after %p\n", __func__,

105 static_cast<const void*> (node),

106 static_cast<const void*> (this));

107#endif // defined(MICRO_OS_PLUS_UTILS_LISTS_TRACE_ENABLED)

108 assert (next_ != nullptr);

109 assert (next_->previous_ != nullptr);

110

111 // Make the new node point to its new neighbours.

112 node->previous_ = this;

113 node->next_ = next_;

114

115 next_->previous_ = node;

116 next_ = node;

117 }

References micro_os_plus::utils::doubly_list_links_base::doubly_list_links_base and micro_os_plus::utils::doubly_list_links_base::next_.

link_previous()

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

noexcept

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 doubly-linked list.

Declaration at line 205 of file doubly-list-links.h, definition at line 129 of file doubly-list-links.cpp.

129 doubly_list_links_base::link_previous (doubly_list_links_base* node) noexcept

130 {

131#if defined(MICRO_OS_PLUS_UTILS_LISTS_TRACE_ENABLED)

132 trace::printf ("%s() link %p before %p\n", __func__,

133 static_cast<const void*> (node),

134 static_cast<const void*> (this));

135#endif // defined(MICRO_OS_PLUS_UTILS_LISTS_TRACE_ENABLED)

136 assert (previous_ != nullptr);

137 assert (previous_->next_ != nullptr);

138

139 // Make the new node point to its new neighbours.

140 node->next_ = this;

141 node->previous_ = previous_;

142

143 previous_->next_ = node;

144 previous_ = node;

145 }

References micro_os_plus::utils::doubly_list_links_base::doubly_list_links_base and micro_os_plus::utils::doubly_list_links_base::previous_.

linked()

bool micro_os_plus::utils::doubly_list_links_base::linked (void)

nodiscard constexpr noexcept

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 227 of file doubly-list-links.h, definition at line 177 of file doubly-list-links-inlines.h.

177 doubly_list_links_base::linked (void) const noexcept

178 {

179 if (next_ == this || previous_ == this)

180 {

181 assert (next_ == this);

182 assert (previous_ == this);

183 return false;

184 }

185 return true;

186 }

References micro_os_plus::utils::doubly_list_links_base::next_ and micro_os_plus::utils::doubly_list_links_base::previous_.

next()

doubly_list_links_base * micro_os_plus::utils::doubly_list_links_base::next (void)

nodiscard constexpr noexcept

Get the link to the next node.

Parameters: None.

Returns: 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.

info

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

Declaration at line 237 of file doubly-list-links.h, definition at line 147 of file doubly-list-links-inlines.h.

147 doubly_list_links_base::next (void) const noexcept

148 {

149 return next_;

150 }

Reference micro_os_plus::utils::doubly_list_links_base::next_.

previous()

doubly_list_links_base * micro_os_plus::utils::doubly_list_links_base::previous (void)

nodiscard constexpr noexcept

Get the link to the previous node.

Parameters: None.

Returns: 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.

info

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

Declaration at line 247 of file doubly-list-links.h, definition at line 164 of file doubly-list-links-inlines.h.

164 doubly_list_links_base::previous (void) const noexcept

165 {

166 return previous_;

167 }

Reference micro_os_plus::utils::doubly_list_links_base::previous_.

unlink()

void micro_os_plus::utils::doubly_list_links_base::unlink (void)

noexcept

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 216 of file doubly-list-links.h, definition at line 155 of file doubly-list-links.cpp.

155 doubly_list_links_base::unlink (void) noexcept

156 {

157#if defined(MICRO_OS_PLUS_UTILS_LISTS_TRACE_ENABLED)

158 trace::printf ("%s() %p \n", __func__, static_cast<const void*> (this));

159#endif // defined(MICRO_OS_PLUS_UTILS_LISTS_TRACE_ENABLED)

160 assert (previous_ != nullptr);

161 assert (next_ != nullptr);

162

163 // Make neighbours point to each other.

164 // This works even if the node is already unlinked,

165 // so no need for an extra test.

166 previous_->next_ = next_;

167 next_->previous_ = previous_;

168

169 // Reset the unlinked node to the initial state,

170 // with both pointers pointing to itself.

171 initialise ();

172 }

References micro_os_plus::utils::doubly_list_links_base::initialise, micro_os_plus::utils::doubly_list_links_base::next_ and micro_os_plus::utils::doubly_list_links_base::previous_.

Protected Member Attributes

next_

doubly_list_links_base* micro_os_plus::utils::doubly_list_links_base::next_

protected

Pointer to the next node.

Definition at line 258 of file doubly-list-links.h.

258 doubly_list_links_base* next_;

Referenced by micro_os_plus::utils::doubly_list_links_base::initialise, micro_os_plus::utils::doubly_list_links_base::initialised, micro_os_plus::utils::doubly_list_links_base::link_next, micro_os_plus::utils::doubly_list_links_base::linked, micro_os_plus::utils::doubly_list_links_base::next, micro_os_plus::utils::static_doubly_list_links::reset and micro_os_plus::utils::doubly_list_links_base::unlink.

previous_

doubly_list_links_base* micro_os_plus::utils::doubly_list_links_base::previous_

protected

Pointer to the previous node.

Definition at line 253 of file doubly-list-links.h.

253 doubly_list_links_base* previous_;

Referenced by micro_os_plus::utils::doubly_list_links_base::initialise, micro_os_plus::utils::doubly_list_links_base::initialised, micro_os_plus::utils::doubly_list_links_base::link_previous, micro_os_plus::utils::doubly_list_links_base::linked, micro_os_plus::utils::doubly_list_links_base::previous, micro_os_plus::utils::static_doubly_list_links::reset and micro_os_plus::utils::doubly_list_links_base::unlink.

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

Generated via doxygen2docusaurus 2.2.2 by Doxygen 1.17.0.

Declaration​

Included Headers​

Base class​

Public Member Typedefs Index​

Public Constructors Index​

Public Destructor Index​

Public Operators Index​

Public Member Functions Index​

Protected Member Attributes Index​

Description​

Public Member Typedefs​

is_statically_allocated​

Public Constructors​

doubly_list_links()​

doubly_list_links()​

doubly_list_links()​

Public Destructor​

~doubly_list_links()​

Public Operators​

operator=()​

operator=()​

Public Member Functions​

initialise()​

initialise_once()​

initialised()​

link_next()​

link_previous()​

linked()​

next()​

previous()​

unlink()​

Protected Member Attributes​

next_​

previous_​

Declaration

Included Headers

Base class

Public Member Typedefs Index

Public Constructors Index

Public Destructor Index

Public Operators Index

Public Member Functions Index

Protected Member Attributes Index

Description

Public Member Typedefs

is_statically_allocated

Public Constructors

doubly_list_links()

doubly_list_links()

doubly_list_links()

Public Destructor

~doubly_list_links()

Public Operators

operator=()

operator=()

Public Member Functions

initialise()

initialise_once()

initialised()

link_next()

link_previous()

linked()

next()

previous()

unlink()

Protected Member Attributes

next_

previous_