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. If the nodes and/or list
  165  * object is shared by multiple threads, explicit steps must be taken to maintain mutual
  166  * exclusion of access.
  167  *
  168  * <HR>
  169  *
  170  * Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.
  171  */
  172 
  173 
  174  /** @file le_doublyLinkedList.h
  175   *
  176   * Legato @ref c_doublyLinkedList include file.
  177   *
  178   * Copyright (C) Sierra Wireless Inc. Use of this work is subject to license.
  179   */
  180 
  181 #ifndef LEGATO_DOUBLY_LINKED_LIST_INCLUDE_GUARD
  182 #define LEGATO_DOUBLY_LINKED_LIST_INCLUDE_GUARD
  183 
  184 
  185 //--------------------------------------------------------------------------------------------------
  186 /**
  187  * This link object must be included in each user node.  The node's link object is used to add the
  188  * node to a list.  A node may have multiple link objects which would allow the node to be part of
  189  * multiple lists simultaneously.  This link object must be initialized by assigning
  190  * LE_DLS_LINK_INIT to it.
  191  *
  192  * @warning The structure's content MUST NOT be accessed directly.
  193  */
  194 //--------------------------------------------------------------------------------------------------
  195 typedef struct le_dls_Link
  196 {
  197     struct le_dls_Link* nextPtr;       ///< Next link pointer.
  198     struct le_dls_Link* prevPtr;       ///< Previous link pointer.
  199 }
  200 le_dls_Link_t;
  201 
  202 
  203 //--------------------------------------------------------------------------------------------------
  204 /**
  205  * This is the list object.  User must create this list object and initialize it by assigning
  206  * LE_DLS_LIST_INIT to it.
  207  *
  208  * @warning User MUST NOT access the contents of this structure directly.
  209  */
  210 //--------------------------------------------------------------------------------------------------
  211 typedef struct
  212 {
  213     le_dls_Link_t* headLinkPtr;        ///< Link to list head.
  214 }
  215 le_dls_List_t;
  216 
  217 
  218 //--------------------------------------------------------------------------------------------------
  219 /**
  220  * When a list is created it must be initialized by assigning this macro to the list before the list
  221  * can be used.
  222  */
  223 //--------------------------------------------------------------------------------------------------
  224 #define LE_DLS_LIST_INIT (le_dls_List_t){NULL}
  225 
  226 
  227 //--------------------------------------------------------------------------------------------------
  228 /**
  229  * When a link is created it must be initialized by assigning this macro to the link before it can
  230  * be used.
  231  */
  232 //--------------------------------------------------------------------------------------------------
  233 #define LE_DLS_LINK_INIT (le_dls_Link_t){NULL, NULL}
  234 
  235 
  236 //--------------------------------------------------------------------------------------------------
  237 /**
  238  * Adds a link at the head of the list.
  239  */
  240 //--------------------------------------------------------------------------------------------------
  241 void le_dls_Stack
  242 (
  243     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  244     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  245 );
  246 
  247 
  248 //--------------------------------------------------------------------------------------------------
  249 /**
  250  * Adds a link to the tail of the list.
  251  */
  252 //--------------------------------------------------------------------------------------------------
  253 void le_dls_Queue
  254 (
  255     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  256     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  257 );
  258 
  259 
  260 //--------------------------------------------------------------------------------------------------
  261 /**
  262  * Adds a link after currentLinkPtr.  User must ensure that currentLinkPtr is in the list
  263  * otherwise the behaviour of this function is undefined.
  264  */
  265 //--------------------------------------------------------------------------------------------------
  266 void le_dls_AddAfter
  267 (
  268     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  269     le_dls_Link_t* currentLinkPtr,     ///< [IN] New link will be inserted after this link.
  270     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  271 );
  272 
  273 
  274 //--------------------------------------------------------------------------------------------------
  275 /**
  276  * Adds a link after currentLinkPtr.  User must ensure that currentLinkPtr is in the list
  277  * otherwise the behaviour of this function is undefined.
  278  */
  279 //--------------------------------------------------------------------------------------------------
  280 void le_dls_AddBefore
  281 (
  282     le_dls_List_t* listPtr,            ///< [IN] List to add to.
  283     le_dls_Link_t* currentLinkPtr,     ///< [IN] New link will be inserted before this link.
  284     le_dls_Link_t* newLinkPtr          ///< [IN] New link to add.
  285 );
  286 
  287 
  288 //--------------------------------------------------------------------------------------------------
  289 /**
  290  * Removes and returns the link at the head of the list.
  291  *
  292  * @return
  293  *      Removed link.
  294  *      NULL if the link is not available because the list is empty.
  295  */
  296 //--------------------------------------------------------------------------------------------------
  297 le_dls_Link_t* le_dls_Pop
  298 (
  299     le_dls_List_t* listPtr             ///< [IN] List to remove from.
  300 );
  301 
  302 
  303 //--------------------------------------------------------------------------------------------------
  304 /**
  305  * Removes and returns the link at the tail of the list.
  306  *
  307  * @return
  308  *      The removed link.
  309  *      NULL if the link is not available because the list is empty.
  310  */
  311 //--------------------------------------------------------------------------------------------------
  312 le_dls_Link_t* le_dls_PopTail
  313 (
  314     le_dls_List_t* listPtr             ///< [IN] List to remove from.
  315 );
  316 
  317 
  318 //--------------------------------------------------------------------------------------------------
  319 /**
  320  * Removes the specified link from the list.  Ensure the link is in the list
  321  * otherwise the behaviour of this function is undefined.
  322  */
  323 //--------------------------------------------------------------------------------------------------
  324 void le_dls_Remove
  325 (
  326     le_dls_List_t* listPtr,             ///< [IN] List to remove from.
  327     le_dls_Link_t* linkToRemovePtr      ///< [IN] Link to remove.
  328 );
  329 
  330 
  331 //--------------------------------------------------------------------------------------------------
  332 /**
  333  * Returns the link at the head of the list without removing it from the list.
  334  *
  335  * @return
  336  *      Pointer to the head link if successful.
  337  *      NULL if the list is empty.
  338  */
  339 //--------------------------------------------------------------------------------------------------
  340 le_dls_Link_t* le_dls_Peek
  341 (
  342     const le_dls_List_t* listPtr            ///< [IN] The list.
  343 );
  344 
  345 
  346 //--------------------------------------------------------------------------------------------------
  347 /**
  348  * Returns the link at the tail of the list without removing it from the list.
  349  *
  350  * @return
  351  *      A pointer to the tail link if successful.
  352  *      NULL if the list is empty.
  353  */
  354 //--------------------------------------------------------------------------------------------------
  355 le_dls_Link_t* le_dls_PeekTail
  356 (
  357     const le_dls_List_t* listPtr            ///< [IN] The list.
  358 );
  359 
  360 
  361 //--------------------------------------------------------------------------------------------------
  362 /**
  363  * Checks if a list is empty.
  364  *
  365  * @return
  366  *      true if empty, false if not empty.
  367  */
  368 //--------------------------------------------------------------------------------------------------
  369 static inline bool le_dls_IsEmpty
  370 (
  371     const le_dls_List_t* listPtr            ///< [IN] The list.
  372 )
  373 //--------------------------------------------------------------------------------------------------
  374 {
  375     return (le_dls_Peek(listPtr) == NULL);
  376 }
  377 
  378 
  379 //--------------------------------------------------------------------------------------------------
  380 /**
  381  * Returns the link next to currentLinkPtr (i.e., the link beside currentLinkPtr that is closer to the
  382  * tail) without removing it from the list.  User must ensure that currentLinkPtr is in the list
  383  * otherwise the behaviour of this function is undefined.
  384  *
  385  * @return
  386  *      Pointer to the next link if successful.
  387  *      NULL if there is no link next to the currentLinkPtr (currentLinkPtr is at the tail of the
  388  *      list).
  389  */
  390 //--------------------------------------------------------------------------------------------------
  391 le_dls_Link_t* le_dls_PeekNext
  392 (
  393     const le_dls_List_t* listPtr,           ///< [IN] List containing currentLinkPtr.
  394     const le_dls_Link_t* currentLinkPtr     ///< [IN] Get the link that is relative to this link.
  395 );
  396 
  397 
  398 //--------------------------------------------------------------------------------------------------
  399 /**
  400  * Returns the link previous to currentLinkPtr without removing it from the list.  User must
  401  * ensure that currentLinkPtr is in the list otherwise the behaviour of this function is undefined.
  402  *
  403  * @return
  404  *      Pointer to the previous link if successful.
  405  *      NULL if there is no link previous to the currentLinkPtr (currentLinkPtr is at the head of
  406  *      the list).
  407  */
  408 //--------------------------------------------------------------------------------------------------
  409 le_dls_Link_t* le_dls_PeekPrev
  410 (
  411     const le_dls_List_t* listPtr,          ///< [IN] List containing currentLinkPtr.
  412     const le_dls_Link_t* currentLinkPtr    ///< [IN] Get the link that is relative to this link.
  413 );
  414 
  415 
  416 //--------------------------------------------------------------------------------------------------
  417 /**
  418  * Swaps the position of two links in the list. User must ensure that both links are in the
  419  * list otherwise the behaviour of this function is undefined.
  420  */
  421 //--------------------------------------------------------------------------------------------------
  422 void le_dls_Swap
  423 (
  424     le_dls_List_t* listPtr,         ///< [IN] List containing the links to swap.
  425     le_dls_Link_t* linkPtr,         ///< [IN] One of the two link pointers to swap.
  426     le_dls_Link_t* otherLinkPtr     ///< [IN] Other link pointer to swap.
  427 );
  428 
  429 
  430 //--------------------------------------------------------------------------------------------------
  431 /**
  432  * Checks if a link is in the list.
  433  *
  434  * @return
  435  *      true if the link is in the list.
  436  *      false if the link is not in the list.
  437  */
  438 //--------------------------------------------------------------------------------------------------
  439 bool le_dls_IsInList
  440 (
  441     const le_dls_List_t* listPtr,    ///< [IN] List to check.
  442     const le_dls_Link_t* linkPtr     ///< [IN] Check if this link is in the list.
  443 );
  444 
  445 
  446 //--------------------------------------------------------------------------------------------------
  447 /**
  448  * Checks if a link is at the head of the list (next to be popped).
  449  *
  450  * @return
  451  *    - true if the link is at the head of the list.
  452  *    - false if not.
  453  */
  454 //--------------------------------------------------------------------------------------------------
  455 static inline bool le_dls_IsHead
  456 (
  457     const le_dls_List_t* listPtr,    ///< [IN] List to check.
  458     const le_dls_Link_t* linkPtr     ///< [IN] Check if this link is at the head of the list.
  459 )
  460 {
  461     return (le_dls_Peek(listPtr) == linkPtr);
  462 }
  463 
  464 
  465 //--------------------------------------------------------------------------------------------------
  466 /**
  467  * Checks if a link is at the tail of the list (last to be popped).
  468  *
  469  * @return
  470  *    - true if the link is at the tail of the list.
  471  *    - false if not.
  472  */
  473 //--------------------------------------------------------------------------------------------------
  474 static inline bool le_dls_IsTail
  475 (
  476     const le_dls_List_t* listPtr,    ///< [IN] List to check.
  477     const le_dls_Link_t* linkPtr     ///< [IN] Check if this link is at the tail of the list.
  478 )
  479 {
  480     return (le_dls_PeekTail(listPtr) == linkPtr);
  481 }
  482 
  483 
  484 //--------------------------------------------------------------------------------------------------
  485 /**
  486  * Returns the number of links in a list.
  487  *
  488  * @return
  489  *      Number of links.
  490  */
  491 //--------------------------------------------------------------------------------------------------
  492 size_t le_dls_NumLinks
  493 (
  494     const le_dls_List_t* listPtr       ///< [IN] List to count.
  495 );
  496 
  497 
  498 //--------------------------------------------------------------------------------------------------
  499 /**
  500  * Checks if the list is corrupted.
  501  *
  502  * @return
  503  *      true if the list is corrupted.
  504  *      false if the list is not corrupted.
  505  */
  506 //--------------------------------------------------------------------------------------------------
  507 bool le_dls_IsListCorrupted
  508 (
  509     const le_dls_List_t* listPtr    ///< [IN] List to check.
  510 );
  511 
  512 #endif  // LEGATO_DOUBLY_LINKED_LIST_INCLUDE_GUARD
  513 
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:456
le_dls_Link_t
Definition: le_doublyLinkedList.h:195
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:197
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:198
le_dls_PopTail
le_dls_Link_t * le_dls_PopTail(le_dls_List_t *listPtr)
le_dls_List_t
Definition: le_doublyLinkedList.h:211
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:213
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:370
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:475
le_dls_Remove
void le_dls_Remove(le_dls_List_t *listPtr, le_dls_Link_t *linkToRemovePtr)