`doubly_list_links_base` Class

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

Declaration

class micro_os_plus::utils::doubly_list_links_base { ... }

Included Headers

Derived Classes

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

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

Public Constructors Index

constexpr	doubly_list_links_base () noexcept
	Construct an uninitialised list node. More...

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

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

Public Destructor Index

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

Public Operators Index

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

doubly_list_links_base &	operator= (doubly_list_links_base &&)=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 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.

info

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

Definition at line 97 of file doubly-list-links.h.

Public Constructors

doubly_list_links_base()

micro_os_plus::utils::doubly_list_links_base::doubly_list_links_base ()

constexpr noexcept

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.

info

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 doubly_list_links_base 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 103 of file doubly-list-links.h, definition at line 82 of file doubly-list-links-inlines.h.

82 constexpr doubly_list_links_base::doubly_list_links_base () noexcept

83 {

84 // Must be empty! No members must be changed by this constructor!

85 }

Referenced by doubly_list_links_base, doubly_list_links_base, link_next, link_previous, operator=, operator= and micro_os_plus::utils::static_doubly_list_links::reset.

doubly_list_links_base()

micro_os_plus::utils::doubly_list_links_base::doubly_list_links_base (const doubly_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.

Definition at line 115 of file doubly-list-links.h.

Reference doubly_list_links_base.

doubly_list_links_base()

micro_os_plus::utils::doubly_list_links_base::doubly_list_links_base (doubly_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.

Definition at line 124 of file doubly-list-links.h.

Reference doubly_list_links_base.

Public Destructor

~doubly_list_links_base()

micro_os_plus::utils::doubly_list_links_base::~doubly_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.

info

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.

Declaration at line 152 of file doubly-list-links.h, definition at line 100 of file doubly-list-links-inlines.h.

100 constexpr doubly_list_links_base::~doubly_list_links_base ()

101 {

102 // Must be empty! No members must be changed by this destructor!

103 }

Public Operators

operator=()

doubly_list_links_base & micro_os_plus::utils::doubly_list_links_base::operator= (const doubly_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.

Definition at line 135 of file doubly-list-links.h.

Reference doubly_list_links_base.

operator=()

doubly_list_links_base & micro_os_plus::utils::doubly_list_links_base::operator= (doubly_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.

Definition at line 146 of file doubly-list-links.h.

Reference doubly_list_links_base.

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 next_ and previous_.

Referenced by micro_os_plus::utils::doubly_list_links::doubly_list_links, initialise_once and 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 initialise and 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 next_ and previous_.

Referenced by 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 doubly_list_links_base and 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 doubly_list_links_base and 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 next_ and 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 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 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 initialise, next_ and 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 initialise, initialised, link_next, linked, next, micro_os_plus::utils::static_doubly_list_links::reset and 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 initialise, initialised, link_previous, linked, previous, micro_os_plus::utils::static_doubly_list_links::reset and 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​

Derived Classes​

Public Constructors Index​

Public Destructor Index​

Public Operators Index​

Public Member Functions Index​

Protected Member Attributes Index​

Description​

Public Constructors​

doubly_list_links_base()​

doubly_list_links_base()​

doubly_list_links_base()​

Public Destructor​

~doubly_list_links_base()​

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

Derived Classes

Public Constructors Index

Public Destructor Index

Public Operators Index

Public Member Functions Index

Protected Member Attributes Index

Description

Public Constructors

doubly_list_links_base()

doubly_list_links_base()

doubly_list_links_base()

Public Destructor

~doubly_list_links_base()

Public Operators

operator=()

operator=()

Public Member Functions

initialise()

initialise_once()

initialised()

link_next()

link_previous()

linked()

next()

previous()

unlink()

Protected Member Attributes

next_

previous_