+++ /dev/null
-#include <glib.h>
-#include "gpqueue.h"
-
-/**
- * SECTION:priority_queues
- * @short_description: a collection of data entries with associated priority
- * values that returns entries one by one in order of priority
- *
- * <para>
- * The #GPQueue structure and its associated functions provide a sorted
- * collection of objects. Entries can be inserted in any order and at any time,
- * and an entry's priority can be changed after it has been inserted into the
- * queue. Entries are supposed to be removed one at a time in order of priority
- * with g_pqueue_pop(), but deleting entries out of order is possible.
- * </para>
- * <para>
- * The entries <emphasis>cannot</emphasis> be iterated over in any way other
- * than removing them one by one in order of priority, but when doing that,
- * this structure is far more efficient than sorted lists or balanced trees,
- * which on the other hand do not suffer from this restriction.
- * </para>
- * <para>
- * You will want to be very careful with calls that use #GPQueueHandle.
- * Handles immediately become invalid when an entry is removed from a #GPQueue,
- * but the current implementation cannot detect this and will do unfortunate
- * things to undefined memory locations if you try to use an invalid handle.
- * </para>
- * <note>
- * <para>
- * Internally, #GPQueue currently uses a Fibonacci heap to store
- * the entries. This implementation detail may change.
- * </para>
- * </note>
- **/
-
-struct _GPQueueNode {
- GPQueueNode *next;
- GPQueueNode *prev;
- GPQueueNode *parent;
- GPQueueNode *child;
-
- gpointer data;
-
- gint degree;
- gboolean marked;
-};
-
-struct _GPQueue {
- GPQueueNode *root;
- GCompareDataFunc cmp;
- gpointer *cmpdata;
-};
-
-/**
- * g_pqueue_new:
- * @compare_func: the #GCompareDataFunc used to sort the new priority queue.
- * This function is passed two elements of the queue and should return 0 if
- * they are equal, a negative value if the first comes before the second, and
- * a positive value if the second comes before the first.
- * @compare_userdata: user data passed to @compare_func
- *
- * Creates a new #GPQueue.
- *
- * Returns: a new #GPQueue.
- *
- * Since: 2.x
- **/
-GPQueue*
-g_pqueue_new (GCompareDataFunc compare_func,
- gpointer *compare_userdata)
-{
- g_return_val_if_fail (compare_func != NULL, NULL);
-
- GPQueue *pqueue = g_slice_new (GPQueue);
- pqueue->root = NULL;
- pqueue->cmp = compare_func;
- pqueue->cmpdata = compare_userdata;
- return pqueue;
-}
-
-/**
- * g_pqueue_is_empty:
- * @pqueue: a #GPQueue.
- *
- * Returns %TRUE if the queue is empty.
- *
- * Returns: %TRUE if the queue is empty.
- *
- * Since: 2.x
- **/
-gboolean
-g_pqueue_is_empty (GPQueue *pqueue)
-{
- return (pqueue->root == NULL);
-}
-
-static void
-g_pqueue_node_foreach (GPQueueNode *node,
- GPQueueNode *stop,
- GFunc func,
- gpointer user_data)
-{
- if (node == NULL || node == stop) return;
- func(node->data, user_data);
- if (stop == NULL) stop = node;
- g_pqueue_node_foreach (node->next, stop, func, user_data);
- g_pqueue_node_foreach (node->child, NULL, func, user_data);
-}
-
-/**
- * g_pqueue_foreach:
- * @pqueue: a #GQueue.
- * @func: the function to call for each element's data
- * @user_data: user data to pass to func
- *
- * Calls func for each element in the pqueue passing user_data to the function.
- *
- * Since: 2.x
- */
-void
-g_pqueue_foreach (GPQueue *pqueue,
- GFunc func,
- gpointer user_data)
-{
- g_pqueue_node_foreach (pqueue->root, NULL, func, user_data);
-}
-
-static void
-g_pqueue_add_ptr_cb (gpointer obj, GPtrArray *ptrs)
-{
- g_ptr_array_add(ptrs, obj);
-}
-/**
- * g_pqueue_get_array:
- * @pqueue: a #GQueue.
- *
- * Construct a GPtrArray for the items in pqueue. This can be useful when
- * updating the priorities of all the elements in pqueue.
- *
- * Returns: A GPtrArray containing a pointer to each item in pqueue
- *
- * Since: 2.x
- */
-GPtrArray *
-g_pqueue_get_array (GPQueue *pqueue)
-{
- GPtrArray *ptrs = g_ptr_array_new();
- g_pqueue_foreach(pqueue, (GFunc)g_pqueue_add_ptr_cb, ptrs);
- return ptrs;
-}
-
-static inline gint
-cmp (GPQueue *pqueue,
- GPQueueNode *a,
- GPQueueNode *b)
-{
- return pqueue->cmp (a->data, b->data, pqueue->cmpdata);
-}
-
-static inline void
-g_pqueue_node_cut (GPQueueNode *src)
-{
- src->prev->next = src->next;
- src->next->prev = src->prev;
- src->next = src;
- src->prev = src;
-}
-
-static inline void
-g_pqueue_node_insert_before (GPQueueNode *dest,
- GPQueueNode *src)
-{
- GPQueueNode *prev;
-
- prev = dest->prev;
- dest->prev = src->prev;
- src->prev->next = dest;
- src->prev = prev;
- prev->next = src;
-}
-
-static inline void
-g_pqueue_node_insert_after (GPQueueNode *dest,
- GPQueueNode *src)
-{
- GPQueueNode *next;
-
- next = dest->next;
- dest->next = src;
- src->prev->next = next;
- next->prev = src->prev;
- src->prev = dest;
-}
-
-/**
- * g_pqueue_push:
- * @pqueue: a #GPQueue.
- * @data: the object to insert into the priority queue.
- *
- * Inserts a new entry into a #GPQueue.
- *
- * The returned handle can be used in calls to g_pqueue_remove() and
- * g_pqueue_priority_changed(). Never make such calls for entries that have
- * already been removed from the queue. The same @data can be inserted into
- * a #GPQueue more than once, but remember that in this case,
- * g_pqueue_priority_changed() needs to be called for
- * <emphasis>every</emphasis> handle for that object if its priority changes.
- *
- * Returns: a handle for the freshly inserted entry.
- *
- * Since: 2.x
- **/
-GPQueueHandle
-g_pqueue_push (GPQueue *pqueue,
- gpointer data)
-{
- GPQueueNode *e;
-
- e = g_slice_new (GPQueueNode);
- e->next = e;
- e->prev = e;
- e->parent = NULL;
- e->child = NULL;
- e->data = data;
- e->degree = 0;
- e->marked = FALSE;
-
- if (pqueue->root != NULL) {
- g_pqueue_node_insert_before (pqueue->root, e);
- if (cmp (pqueue, e, pqueue->root) < 0)
- pqueue->root = e;
- } else {
- pqueue->root = e;
- }
-
- return e;
-}
-
-/**
- * g_pqueue_peek:
- * @pqueue: a #GPQueue.
- *
- * Returns the topmost entry's data pointer, or %NULL if the queue is empty.
- *
- * If you need to tell the difference between an empty queue and a queue
- * that happens to have a %NULL pointer at the top, check if the queue is
- * empty first.
- *
- * Returns: the topmost entry's data pointer, or %NULL if the queue is empty.
- *
- * Since: 2.x
- **/
-gpointer
-g_pqueue_peek (GPQueue *pqueue)
-{
- return (pqueue->root != NULL) ? pqueue->root->data : NULL;
-}
-
-static inline GPQueueNode*
-g_pqueue_make_child (GPQueueNode *a,
- GPQueueNode *b)
-{
- g_pqueue_node_cut(b);
- if (a->child != NULL) {
- g_pqueue_node_insert_before (a->child, b);
- a->degree += 1;
- } else {
- a->child = b;
- a->degree = 1;
- }
- b->parent = a;
- return a;
-}
-
-static inline GPQueueNode*
-g_pqueue_join_trees (GPQueue *pqueue,
- GPQueueNode *a,
- GPQueueNode *b)
-{
- if (cmp (pqueue, a, b) < 0)
- return g_pqueue_make_child (a, b);
- return g_pqueue_make_child (b, a);
-}
-
-static void
-g_pqueue_fix_rootlist (GPQueue* pqueue)
-{
- gsize degnode_size;
- GPQueueNode **degnode;
- GPQueueNode sentinel;
- GPQueueNode *current;
- GPQueueNode *minimum;
-
- /* We need to iterate over the circular list we are given and do
- * several things:
- * - Make sure all the elements are unmarked
- * - Make sure to return the element in the list with smallest
- * priority value
- * - Find elements of identical degree and join them into trees
- * The last point is irrelevant for correctness, but essential
- * for performance. If we did not do this, our data structure would
- * degrade into an unsorted linked list.
- */
-
- degnode_size = (8 * sizeof(gpointer) + 1) * sizeof(gpointer);
- degnode = g_slice_alloc0 (degnode_size);
-
- sentinel.next = &sentinel;
- sentinel.prev = &sentinel;
- g_pqueue_node_insert_before (pqueue->root, &sentinel);
-
- current = pqueue->root;
- while (current != &sentinel) {
- current->marked = FALSE;
- current->parent = NULL;
- gint d = current->degree;
- if (degnode[d] == NULL) {
- degnode[d] = current;
- current = current->next;
- } else {
- if (degnode[d] != current) {
- current = g_pqueue_join_trees (pqueue, degnode[d], current);
- degnode[d] = NULL;
- } else {
- current = current->next;
- }
- }
- }
-
- current = sentinel.next;
- minimum = current;
- while (current != &sentinel) {
- if (cmp (pqueue, current, minimum) < 0)
- minimum = current;
- current = current->next;
- }
- pqueue->root = minimum;
-
- g_pqueue_node_cut (&sentinel);
-
- g_slice_free1 (degnode_size, degnode);
-}
-
-static void
-g_pqueue_remove_root (GPQueue *pqueue,
- GPQueueNode *root)
-{
- /* This removes a node at the root _level_ of the structure, which can be,
- * but does not have to be, the actual pqueue->root node. That is why
- * we require an explicit pointer to the node to be removed instead of just
- * removing pqueue->root implictly.
- */
-
- /* Step one:
- * If root has any children, pull them up to root level.
- * At this time, we only deal with their next/prev pointers,
- * further changes are made later in g_pqueue_fix_rootlist().
- */
- if (root->child) {
- g_pqueue_node_insert_after (root, root->child);
- root->child = NULL;
- root->degree = 0;
- }
-
- /* Step two:
- * Cut root out of the list.
- */
- if (root->next != root) {
- pqueue->root = root->next;
- g_pqueue_node_cut (root);
- /* Step three:
- * Clean up the remaining list.
- */
- g_pqueue_fix_rootlist (pqueue);
- } else {
- pqueue->root = NULL;
- }
-
- g_slice_free (GPQueueNode, root);
-}
-
-/**
- * g_pqueue_pop:
- * @pqueue: a #GPQueue.
- *
- * Removes the topmost entry from a #GPQueue and returns its data pointer.
- * Calling this on an empty #GPQueue is not an error, but removes nothing
- * and returns %NULL.
- *
- * If you need to tell the difference between an empty queue and a queue
- * that happens to have a %NULL pointer at the top, check if the queue is
- * empty first.
- *
- * Returns: the topmost entry's data pointer, or %NULL if the queue was empty.
- *
- * Since: 2.x
- **/
-gpointer
-g_pqueue_pop (GPQueue *pqueue)
-{
- gpointer data;
-
- if (pqueue->root == NULL) return NULL;
- data = pqueue->root->data;
- g_pqueue_remove_root (pqueue, pqueue->root);
- return data;
-}
-
-static inline void
-g_pqueue_make_root (GPQueue *pqueue,
- GPQueueNode *entry)
-{
- /* This moves a node up to the root _level_ of the structure.
- * It does not always become the actual root element (pqueue->root).
- */
-
- GPQueueNode *parent;
-
- parent = entry->parent;
- entry->parent = NULL;
- entry->marked = FALSE;
- if (parent != NULL) {
- if (entry->next != entry) {
- if (parent->child == entry) parent->child = entry->next;
- g_pqueue_node_cut (entry);
- parent->degree -= 1;
- } else {
- parent->child = NULL;
- parent->degree = 0;
- }
- g_pqueue_node_insert_before (pqueue->root, entry);
- }
-
- if (cmp (pqueue, entry, pqueue->root) < 0)
- pqueue->root = entry;
-}
-
-static void
-g_pqueue_cut_tree (GPQueue *pqueue,
- GPQueueNode *entry)
-{
- /* This function moves an entry up to the root level of the structure.
- * It extends g_pqueue_make_root() in that the entry's parent, grandparent
- * etc. may also be moved to the root level if they are "marked". This is
- * not essential for correctness, it just maintains the so-called "potential"
- * of the structure, which is necessary for the amortized runtime analysis.
- */
-
- GPQueueNode *current;
- GPQueueNode *parent;
-
- current = entry;
- while ((current != NULL) && (current->parent != NULL)) {
- parent = current->parent;
- g_pqueue_make_root (pqueue, entry);
- if (parent->marked) {
- current = parent;
- } else {
- parent->marked = TRUE;
- current = NULL;
- }
- }
- if (cmp (pqueue, entry, pqueue->root) < 0)
- pqueue->root = entry;
-}
-
-/**
- * g_pqueue_remove:
- * @pqueue: a #GPQueue.
- * @entry: a #GPQueueHandle for an entry in @pqueue.
- *
- * Removes one entry from a #GPQueue.
- *
- * Make sure that @entry refers to an entry that is actually part of
- * @pqueue at the time, otherwise the behavior of this function is
- * undefined (expect crashes).
- *
- * Since: 2.x
- **/
-void
-g_pqueue_remove (GPQueue* pqueue,
- GPQueueHandle entry)
-{
- g_pqueue_cut_tree (pqueue, entry);
- g_pqueue_remove_root (pqueue, entry);
-}
-
-/**
- * g_pqueue_priority_changed:
- * @pqueue: a #GPQueue.
- * @entry: a #GPQueueHandle for an entry in @pqueue.
- *
- * Notifies the #GPQueue that the priority of one entry has changed.
- * The internal representation is updated accordingly.
- *
- * Make sure that @entry refers to an entry that is actually part of
- * @pqueue at the time, otherwise the behavior of this function is
- * undefined (expect crashes).
- *
- * Do not attempt to change the priorities of several entries at once.
- * Every time a single object is changed, the #GPQueue needs to be updated
- * by calling g_pqueue_priority_changed() for that object.
- *
- * Since: 2.x
- **/
-void
-g_pqueue_priority_changed (GPQueue* pqueue,
- GPQueueHandle entry)
-{
- g_pqueue_cut_tree (pqueue, entry);
-
- if (entry->child) {
- g_pqueue_node_insert_after (entry, entry->child);
- entry->child = NULL;
- entry->degree = 0;
- }
-
- g_pqueue_fix_rootlist (pqueue);
-}
-
-/**
- * g_pqueue_priority_decreased:
- * @pqueue: a #GPQueue.
- * @entry: a #GPQueueHandle for an entry in @pqueue.
- *
- * Notifies the #GPQueue that the priority of one entry has
- * <emphasis>decreased</emphasis>.
- *
- * This is a special case of g_pqueue_priority_changed(). If you are absolutely
- * sure that the new priority of @entry is lower than it was before, you
- * may call this function instead of g_pqueue_priority_changed().
- *
- * <note>
- * <para>
- * In the current implementation, an expensive step in
- * g_pqueue_priority_changed() can be skipped if the new priority is known
- * to be lower, leading to an amortized running time of O(1) instead of
- * O(log n). Of course, if the priority is not actually lower, behavior
- * is undefined.
- * </para>
- * </note>
- *
- * Since: 2.x
- **/
-void
-g_pqueue_priority_decreased (GPQueue* pqueue,
- GPQueueHandle entry)
-{
- g_pqueue_cut_tree (pqueue, entry);
-}
-
-static void
-g_pqueue_node_free_all (GPQueueNode *node)
-{
- if (node == NULL) return;
- g_pqueue_node_free_all (node->child);
- node->prev->next = NULL;
- g_pqueue_node_free_all (node->next);
- g_slice_free (GPQueueNode, node);
-}
-
-/**
- * g_pqueue_clear:
- * @pqueue: a #GPQueue.
- *
- * Removes all entries from a @pqueue.
- *
- * Since: 2.x
- **/
-void
-g_pqueue_clear (GPQueue* pqueue)
-{
- g_pqueue_node_free_all (pqueue->root);
- pqueue->root = NULL;
-}
-
-/**
- * g_pqueue_free:
- * @pqueue: a #GPQueue.
- *
- * Deallocates the memory used by @pqueue itself, but not any memory pointed
- * to by the data pointers of its entries.
- *
- * Since: 2.x
- **/
-void
-g_pqueue_free (GPQueue* pqueue)
-{
- g_pqueue_clear (pqueue);
- g_slice_free (GPQueue, pqueue);
-}
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