le_doublyLinkedList.h

    1 /**
    2  * @page c_doublyLinkedList Doubly Linked List API
    3  *
    4  * @ref le_doublyLinkedList.h "API Reference"
    5  *
    6  * <HR>
    7  *
    8  * A doubly linked list is a data structure consisting of a group of nodes linked together linearly.
    9  * Each node consists of data elements with links to the next node and previous nodes.  The main
   10  * advantage of linked lists (over simple arrays) is the nodes can be inserted and removed
   11  * anywhere in the list without reallocating the entire array. Linked list nodes don't
   12  * need to be stored contiguously in memory, but nodes then you can't access by
   13  * index, you have to be access by traversing the list.
   14  *
   15  * @section dls_createList Creating and Initializing Lists
   16  *
   17  * To create and initialize a linked list the user must create a le_dls_List_t typed list and assign
   18  * LE_DLS_LIST_INIT to it.  The assignment of LE_DLS_LIST_INIT can be done either when the list is
   19  * declared or after its declared.  The list <b>must</b> be initialized before it can be
   20  * used.
   21  *
   22  * @code
   23  * // Create and initialized the list in the declaration.
   24  * le_dls_List_t MyList = LE_DLS_LIST_INIT;
   25  * @endcode
   26  *
   27  * Or
   28  *
   29  * @code
   30  * // Create list.
   31  * le_dls_List_t MyList;
   32  *
   33  * // Initialize the list.
   34  * MyList = LE_DLS_LIST_INIT;
   35  * @endcode
   36  *
   37  * <b> Elements of le_dls_List_t MUST NOT be accessed directly by the user. </b>
   38  *
   39  *
   40  * @section dls_createNode Creating and Accessing Nodes
   41  *
   42  * Nodes can contain any data in any format and is defined and created by the user.  The only
   43  * requirement for nodes is that it must contain a @c le_dls_Link_t link member. The link member must
   44  * be initialized by assigning LE_DLS_LINK_INIT to it before it can be used.  Nodes can then be
   45  * added to the list by passing their links to the add functions (le_dls_Stack(), le_dls_Queue(),
   46  * etc.).  For example:
   47  *
   48  * @code
   49  * // The node may be defined like this.
   50  * typedef struct
   51  * {
   52  *      dataType someUserData;
   53  *      ...
   54  *      le_dls_Link_t myLink;
   55  *
   56  * }
   57  * MyNodeClass_t;
   58  *
   59  * // Create and initialize the list.
   60  * le_dls_List_t MyList = LE_DLS_LIST_INIT;
   61  *
   62  * void foo (void)
   63  * {
   64  *     // Create the node.  Get the memory from a memory pool previously created.
   65  *     MyNodeClass_t* myNodePtr = le_mem_ForceAlloc(MyNodePool);
   66  *
   67  *     // Initialize the node's link.
   68  *     myNodePtr->myLink = LE_DLS_LINK_INIT;
   69  *
   70  *     // Add the node to the head of the list by passing in the node's link.
   71  *     le_dls_Stack(&MyList, &(myNodePtr->myLink));
   72  * }
   73  * @endcode
   74  *
   75  * The links in the nodes are actually added to the list and not the nodes themselves. This
   76  * allows a node to be included on multiple lists through links
   77  * added to different lists. It also allows linking different type nodes in a list.
   78  *
   79  * To obtain the node itself, use the @c CONTAINER_OF macro defined in
   80  * le_basics.h.  Here's a code sample using CONTAINER_OF to obtain the node:
   81  *
   82  * @code
   83  * // Assuming mylist has been created and initialized and is not empty.
   84  * le_dls_link_t* linkPtr = le_dls_Peek(&MyList);
   85  *
   86  * // Now we have the link but still need the node to access user data.
   87  * // We use CONTAINER_OF to get a pointer to the node given the node's link.
   88  * if (linkPtr != NULL)
   89  * {
   90  *     MyNodeClass_t* myNodePtr = CONTAINER_OF(linkPtr, MyNodeClass_t, myLink);
   91  * }
   92  * @endcode
   93  *
   94  * The user is responsible for creating and freeing memory for all nodes; the linked list module
   95  * only manages the links in the nodes.  The node must be removed from all lists before its
   96  * memory can be freed.
   97  *
   98  * <b>The elements of @c le_dls_Link_t MUST NOT be accessed directly by the user.</b>
   99  *
  100  *
  101  * @section dls_add Adding Links to a List
  102  *
  103  * To add nodes to a list, pass the node's link to one of these functions:
  104  *
  105  * - @c le_dls_Stack() - Adds the link to the head of the list.
  106  * - @c le_dls_Queue() - Adds the link to the tail of the list.
  107  * - @c le_dls_AddAfter() - Adds the link to a list after another specified link.
  108  * - @c le_dls_AddBefore() - Adds the link to a list before another specified link.
  109  *
  110  *
  111  * @section dls_remove Removing Links from a List
  112  *
  113  * To remove nodes from a list, use one of these functions:
  114  *
  115  * - @c le_dls_Pop() - Removes and returns the link at the head of the list.
  116  * - @c le_dls_PopTail() - Removes and returns the link at the tail of the list.
  117  * - @c le_dls_Remove() - Remove a specified link from the list.
  118  *
  119  *
  120  * @section dls_peek Accessing Links in a List
  121  *
  122  * To access a link in a list without removing the link, use one of these functions:
  123  *
  124  * - @c le_dls_Peek() - Returns the link at the head of the list without removing it.
  125  * - @c le_dls_PeekTail() - Returns the link at the tail of the list without removing it.
  126  * - @c le_dls_PeekNext() - Returns the link next to a specified link without removing it.
  127  * - @c le_dls_PeekPrev() - Returns the link previous to a specified link without removing it.
  128  *
  129  *
  130  * @section dls_swap Swapping Links
  131  *
  132  * To swap two links, use:
  133  *
  134  * - @c le_dls_Swap() - Swaps the position of two links in a list.
  135  *
  136  * The le_dls_Swap() function can be used to sort a list.
  137  *
  138  *
  139  * @section dls_query Querying List Status
  140  *
  141  * These functions can be used to query a list's current status:
  142  *
  143  * - @c le_dls_IsEmpty() - Checks if a given list is empty.
  144  * - @c le_dls_IsInList() - Checks if a specified link is in the list.
  145  * - @c le_dls_IsHead() - Checks if a specified link is at the head of the list.
  146  * - @c le_dls_IsTail() - Checks if a specified link is at the tail of the list.
  147  * - @c le_dls_NumLinks() - Checks the number of links currently in the list.
  148  * - @c le_dls_IsListCorrupted() - Checks if the list is corrupted.
  149  *
  150  *
  151  * @section dls_fifo Queues and Stacks
  152  *
  153  * This implementation of linked lists can be used for either queues or stacks.
  154  *
  155  * To use the list as a queue, restrict additions to the list to @c le_dls_Queue() and removals
  156  * from the list to @c le_dls_Pop().
  157  *
  158  * To use the list as a stack,  restrict additions to the list to @c le_dls_Stack() and removals
  159  * from the list to @c le_dls_Pop().
  160  *
  161  *
  162  * @section dls_synch Thread Safety and Re-Entrancy
  163  *
  164  * All linked list function calls are re-entrant and thread safe themselves, but if the nodes and/or
  165  * list object are shared by multiple threads, explicit steps must be taken to maintain mutual
  166  * exclusion of access. If you're accessing the same list from multiple threads, you @e must use a
  167  * @ref c_mutex "mutex" or some other form of thread synchronization to ensure only one thread
  168  * accesses the list at a time.
  169  *
  170  * <HR>
  171  *
  172  * Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.
  173  */
  174 
  175 
  176  /** @file le_doublyLinkedList.h
  177   *
  178   * Legato @ref c_doublyLinkedList include file.
  179   *
  180   * Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.
  181   */
  182 
  183 #ifndef LEGATO_DOUBLY_LINKED_LIST_INCLUDE_GUARD
  184 #define LEGATO_DOUBLY_LINKED_LIST_INCLUDE_GUARD
  185 
  186 
  187 //--------------------------------------------------------------------------------------------------
  188 /**
  189  * This link object must be included in each user node.  The node's link object is used to add the
  190  * node to a list.  A node may have multiple link objects which would allow the node to be part of
  191  * multiple lists simultaneously.  This link object must be initialized by assigning
  192  * LE_DLS_LINK_INIT to it.
  193  *
  194  * @warning The structure's content MUST NOT be accessed directly.
  195  */
  196 //--------------------------------------------------------------------------------------------------
  197 typedef struct le_dls_Link
  198 {
  199     struct le_dls_Link* nextPtr;       ///< Next link pointer.
  200     struct le_dls_Link* prevPtr;       ///< Previous link pointer.
  201 }
  202 le_dls_Link_t;
  203 
  204 
  205 //--------------------------------------------------------------------------------------------------
  206 /**
  207  * This is the list object.  User must create this list object and initialize it by assigning
  208  * LE_DLS_LIST_INIT to it.
  209  *
  210  * @warning User MUST NOT access the contents of this structure directly.
  211  */
  212 //--------------------------------------------------------------------------------------------------
  213 typedef struct
  214 {
  215     le_dls_Link_t* headLinkPtr;        ///< Link to list head.
  216 }
  217 le_dls_List_t;
  218 
  219 
  220 //--------------------------------------------------------------------------------------------------
  221 /**
  222  * When a list is created it must be initialized by assigning this macro to the list before the list
  223  * can be used.
  224  */
  225 //--------------------------------------------------------------------------------------------------
  226 #define LE_DLS_LIST_INIT (le_dls_List_t){NULL}
  227 
  228 
  229 //--------------------------------------------------------------------------------------------------
  230 /**
  231  * When a link is created it must be initialized by assigning this macro to the link before it can
  232  * be used.
  233  */
  234 //--------------------------------------------------------------------------------------------------
  235 #define LE_DLS_LINK_INIT (le_dls_Link_t){NULL, NULL}
  236 
  237 
  238 //--------------------------------------------------------------------------------------------------
  239 /**
  240  * Adds a link at the head of the list.
  241  */
  242 //--------------------------------------------------------------------------------------------------
  243 void le_dls_Stack
  244 (
  245     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  246     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  247 );
  248 
  249 
  250 //--------------------------------------------------------------------------------------------------
  251 /**
  252  * Adds a link to the tail of the list.
  253  */
  254 //--------------------------------------------------------------------------------------------------
  255 void le_dls_Queue
  256 (
  257     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  258     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  259 );
  260 
  261 
  262 //--------------------------------------------------------------------------------------------------
  263 /**
  264  * Adds a link after currentLinkPtr.  User must ensure that currentLinkPtr is in the list
  265  * otherwise the behaviour of this function is undefined.
  266  */
  267 //--------------------------------------------------------------------------------------------------
  268 void le_dls_AddAfter
  269 (
  270     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  271     le_dls_Link_t* currentLinkPtr,     ///< [IN] New link will be inserted after this link.
  272     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  273 );
  274 
  275 
  276 //--------------------------------------------------------------------------------------------------
  277 /**
  278  * Adds a link after currentLinkPtr.  User must ensure that currentLinkPtr is in the list
  279  * otherwise the behaviour of this function is undefined.
  280  */
  281 //--------------------------------------------------------------------------------------------------
  282 void le_dls_AddBefore
  283 (
  284     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  285     le_dls_Link_t* currentLinkPtr,     ///< [IN] New link will be inserted before this link.
  286     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  287 );
  288 
  289 
  290 //--------------------------------------------------------------------------------------------------
  291 /**
  292  * Removes and returns the link at the head of the list.
  293  *
  294  * @return
  295  *      Removed link.
  296  *      NULL if the link is not available because the list is empty.
  297  */
  298 //--------------------------------------------------------------------------------------------------
  299 le_dls_Link_t* le_dls_Pop
  300 (
  301     le_dls_List_t* listPtr             ///< [IN] List to remove from.
  302 );
  303 
  304 
  305 //--------------------------------------------------------------------------------------------------
  306 /**
  307  * Removes and returns the link at the tail of the list.
  308  *
  309  * @return
  310  *      The removed link.
  311  *      NULL if the link is not available because the list is empty.
  312  */
  313 //--------------------------------------------------------------------------------------------------
  314 le_dls_Link_t* le_dls_PopTail
  315 (
  316     le_dls_List_t* listPtr             ///< [IN] List to remove from.
  317 );
  318 
  319 
  320 //--------------------------------------------------------------------------------------------------
  321 /**
  322  * Removes the specified link from the list.  Ensure the link is in the list
  323  * otherwise the behaviour of this function is undefined.
  324  */
  325 //--------------------------------------------------------------------------------------------------
  326 void le_dls_Remove
  327 (
  328     le_dls_List_t* listPtr,             ///< [IN] List to remove from.
  329     le_dls_Link_t* linkToRemovePtr      ///< [IN] Link to remove.
  330 );
  331 
  332 
  333 //--------------------------------------------------------------------------------------------------
  334 /**
  335  * Returns the link at the head of the list without removing it from the list.
  336  *
  337  * @return
  338  *      Pointer to the head link if successful.
  339  *      NULL if the list is empty.
  340  */
  341 //--------------------------------------------------------------------------------------------------
  342 le_dls_Link_t* le_dls_Peek
  343 (
  344     const le_dls_List_t* listPtr            ///< [IN] The list.
  345 );
  346 
  347 
  348 //--------------------------------------------------------------------------------------------------
  349 /**
  350  * Returns the link at the tail of the list without removing it from the list.
  351  *
  352  * @return
  353  *      A pointer to the tail link if successful.
  354  *      NULL if the list is empty.
  355  */
  356 //--------------------------------------------------------------------------------------------------
  357 le_dls_Link_t* le_dls_PeekTail
  358 (
  359     const le_dls_List_t* listPtr            ///< [IN] The list.
  360 );
  361 
  362 
  363 //--------------------------------------------------------------------------------------------------
  364 /**
  365  * Checks if a list is empty.
  366  *
  367  * @return
  368  *      true if empty, false if not empty.
  369  */
  370 //--------------------------------------------------------------------------------------------------
  371 static inline bool le_dls_IsEmpty
  372 (
  373     const le_dls_List_t* listPtr            ///< [IN] The list.
  374 )
  375 //--------------------------------------------------------------------------------------------------
  376 {
  377     return (le_dls_Peek(listPtr) == NULL);
  378 }
  379 
  380 
  381 //--------------------------------------------------------------------------------------------------
  382 /**
  383  * Returns the link next to currentLinkPtr (i.e., the link beside currentLinkPtr that is closer to the
  384  * tail) without removing it from the list.  User must ensure that currentLinkPtr is in the list
  385  * otherwise the behaviour of this function is undefined.
  386  *
  387  * @return
  388  *      Pointer to the next link if successful.
  389  *      NULL if there is no link next to the currentLinkPtr (currentLinkPtr is at the tail of the
  390  *      list).
  391  */
  392 //--------------------------------------------------------------------------------------------------
  393 le_dls_Link_t* le_dls_PeekNext
  394 (
  395     const le_dls_List_t* listPtr,           ///< [IN] List containing currentLinkPtr.
  396     const le_dls_Link_t* currentLinkPtr     ///< [IN] Get the link that is relative to this link.
  397 );
  398 
  399 
  400 //--------------------------------------------------------------------------------------------------
  401 /**
  402  * Returns the link previous to currentLinkPtr without removing it from the list.  User must
  403  * ensure that currentLinkPtr is in the list otherwise the behaviour of this function is undefined.
  404  *
  405  * @return
  406  *      Pointer to the previous link if successful.
  407  *      NULL if there is no link previous to the currentLinkPtr (currentLinkPtr is at the head of
  408  *      the list).
  409  */
  410 //--------------------------------------------------------------------------------------------------
  411 le_dls_Link_t* le_dls_PeekPrev
  412 (
  413     const le_dls_List_t* listPtr,          ///< [IN] List containing currentLinkPtr.
  414     const le_dls_Link_t* currentLinkPtr    ///< [IN] Get the link that is relative to this link.
  415 );
  416 
  417 
  418 //--------------------------------------------------------------------------------------------------
  419 /**
  420  * Swaps the position of two links in the list. User must ensure that both links are in the
  421  * list otherwise the behaviour of this function is undefined.
  422  */
  423 //--------------------------------------------------------------------------------------------------
  424 void le_dls_Swap
  425 (
  426     le_dls_List_t* listPtr,         ///< [IN] List containing the links to swap.
  427     le_dls_Link_t* linkPtr,         ///< [IN] One of the two link pointers to swap.
  428     le_dls_Link_t* otherLinkPtr     ///< [IN] Other link pointer to swap.
  429 );
  430 
  431 
  432 //--------------------------------------------------------------------------------------------------
  433 /**
  434  * Checks if a link is in the list.
  435  *
  436  * @return
  437  *      true if the link is in the list.
  438  *      false if the link is not in the list.
  439  */
  440 //--------------------------------------------------------------------------------------------------
  441 bool le_dls_IsInList
  442 (
  443     const le_dls_List_t* listPtr,    ///< [IN] List to check.
  444     const le_dls_Link_t* linkPtr     ///< [IN] Check if this link is in the list.
  445 );
  446 
  447 
  448 //--------------------------------------------------------------------------------------------------
  449 /**
  450  * Checks if a link is at the head of the list (next to be popped).
  451  *
  452  * @return
  453  *    - true if the link is at the head of the list.
  454  *    - false if not.
  455  */
  456 //--------------------------------------------------------------------------------------------------
  457 static inline bool le_dls_IsHead
  458 (
  459     const le_dls_List_t* listPtr,    ///< [IN] List to check.
  460     const le_dls_Link_t* linkPtr     ///< [IN] Check if this link is at the head of the list.
  461 )
  462 {
  463     return (le_dls_Peek(listPtr) == linkPtr);
  464 }
  465 
  466 
  467 //--------------------------------------------------------------------------------------------------
  468 /**
  469  * Checks if a link is at the tail of the list (last to be popped).
  470  *
  471  * @return
  472  *    - true if the link is at the tail of the list.
  473  *    - false if not.
  474  */
  475 //--------------------------------------------------------------------------------------------------
  476 static inline bool le_dls_IsTail
  477 (
  478     const le_dls_List_t* listPtr,    ///< [IN] List to check.
  479     const le_dls_Link_t* linkPtr     ///< [IN] Check if this link is at the tail of the list.
  480 )
  481 {
  482     return (le_dls_PeekTail(listPtr) == linkPtr);
  483 }
  484 
  485 
  486 //--------------------------------------------------------------------------------------------------
  487 /**
  488  * Returns the number of links in a list.
  489  *
  490  * @return
  491  *      Number of links.
  492  */
  493 //--------------------------------------------------------------------------------------------------
  494 size_t le_dls_NumLinks
  495 (
  496     const le_dls_List_t* listPtr       ///< [IN] List to count.
  497 );
  498 
  499 
  500 //--------------------------------------------------------------------------------------------------
  501 /**
  502  * Checks if the list is corrupted.
  503  *
  504  * @return
  505  *      true if the list is corrupted.
  506  *      false if the list is not corrupted.
  507  */
  508 //--------------------------------------------------------------------------------------------------
  509 bool le_dls_IsListCorrupted
  510 (
  511     const le_dls_List_t* listPtr    ///< [IN] List to check.
  512 );
  513 
  514 #endif  // LEGATO_DOUBLY_LINKED_LIST_INCLUDE_GUARD
  515 
le_dls_AddAfter
void le_dls_AddAfter(le_dls_List_t *listPtr, le_dls_Link_t *currentLinkPtr, le_dls_Link_t *newLinkPtr)
le_dls_PeekTail
le_dls_Link_t * le_dls_PeekTail(const le_dls_List_t *listPtr)
le_dls_IsHead
static bool le_dls_IsHead(const le_dls_List_t *listPtr, const le_dls_Link_t *linkPtr)
Definition: le_doublyLinkedList.h:458
le_dls_Link_t
Definition: le_doublyLinkedList.h:197
le_dls_PeekPrev
le_dls_Link_t * le_dls_PeekPrev(const le_dls_List_t *listPtr, const le_dls_Link_t *currentLinkPtr)
le_dls_Link_t::nextPtr
struct le_dls_Link * nextPtr
Next link pointer. 
Definition: le_doublyLinkedList.h:199
le_dls_IsListCorrupted
bool le_dls_IsListCorrupted(const le_dls_List_t *listPtr)
le_dls_AddBefore
void le_dls_AddBefore(le_dls_List_t *listPtr, le_dls_Link_t *currentLinkPtr, le_dls_Link_t *newLinkPtr)
le_dls_Queue
void le_dls_Queue(le_dls_List_t *listPtr, le_dls_Link_t *newLinkPtr)
le_dls_Link_t::prevPtr
struct le_dls_Link * prevPtr
Previous link pointer. 
Definition: le_doublyLinkedList.h:200
le_dls_PopTail
le_dls_Link_t * le_dls_PopTail(le_dls_List_t *listPtr)
le_dls_List_t
Definition: le_doublyLinkedList.h:213
le_dls_Pop
le_dls_Link_t * le_dls_Pop(le_dls_List_t *listPtr)
le_dls_Stack
void le_dls_Stack(le_dls_List_t *listPtr, le_dls_Link_t *newLinkPtr)
le_dls_List_t::headLinkPtr
le_dls_Link_t * headLinkPtr
Link to list head. 
Definition: le_doublyLinkedList.h:215
le_dls_IsInList
bool le_dls_IsInList(const le_dls_List_t *listPtr, const le_dls_Link_t *linkPtr)
le_dls_NumLinks
size_t le_dls_NumLinks(const le_dls_List_t *listPtr)
le_dls_Swap
void le_dls_Swap(le_dls_List_t *listPtr, le_dls_Link_t *linkPtr, le_dls_Link_t *otherLinkPtr)
le_dls_Peek
le_dls_Link_t * le_dls_Peek(const le_dls_List_t *listPtr)
le_dls_IsEmpty
static bool le_dls_IsEmpty(const le_dls_List_t *listPtr)
Definition: le_doublyLinkedList.h:372
le_dls_PeekNext
le_dls_Link_t * le_dls_PeekNext(const le_dls_List_t *listPtr, const le_dls_Link_t *currentLinkPtr)
le_dls_IsTail
static bool le_dls_IsTail(const le_dls_List_t *listPtr, const le_dls_Link_t *linkPtr)
Definition: le_doublyLinkedList.h:477
le_dls_Remove
void le_dls_Remove(le_dls_List_t *listPtr, le_dls_Link_t *linkToRemovePtr)