diff options
Diffstat (limited to 'src/list.h')
| -rw-r--r-- | src/list.h | 447 |
1 files changed, 288 insertions, 159 deletions
@@ -3,225 +3,354 @@ /** * Intrusive linked lists. + * + * Singly-linked lists are declared like this: + * + * struct item { + * struct item *next; + * }; + * + * struct list { + * struct item *head; + * struct item **tail; + * }; + * + * The SLIST_*() macros manipulate singly-linked lists. + * + * struct list list; + * SLIST_INIT(&list); + * + * struct item item; + * SLIST_APPEND(&list, &item); + * + * Doubly linked lists are similar: + * + * struct item { + * struct item *next; + * struct item *prev; + * }; + * + * struct list { + * struct item *head; + * struct item *tail; + * }; + * + * struct list list; + * LIST_INIT(&list); + * + * struct item item; + * LIST_APPEND(&list, &item); + * + * Items can be on multiple lists at once: + * + * struct item { + * struct { + * struct item *next; + * } chain; + * + * struct { + * struct item *next; + * struct item *prev; + * } lru; + * }; + * + * struct items { + * struct { + * struct item *head; + * struct item **tail; + * } queue; + * + * struct { + * struct item *head; + * struct item *tail; + * } cache; + * }; + * + * struct items items; + * SLIST_INIT(&items.queue); + * LIST_INIT(&items.cache); + * + * struct item item; + * SLIST_APPEND(&items.queue, &item, chain); + * LIST_APPEND(&items.cache, &item, lru); */ #ifndef BFS_LIST_H #define BFS_LIST_H -#include "config.h" -#include <stdbool.h> +#include <stddef.h> /** - * A singly-linked list entry. + * Initialize a singly-linked list. + * + * @param list + * The list to initialize. + * + * --- + * + * Like many macros in this file, this macro delegates the bulk of its work to + * some helper macros. We explicitly parenthesize (list) here so the helpers + * don't have to. */ -struct slink { - struct slink *next; -}; +#define SLIST_INIT(list) \ + LIST_BLOCK_(SLIST_INIT_((list))) -/** Initialize a list entry. */ -void slink_init(struct slink *link); +#define SLIST_INIT_(list) \ + (list)->head = NULL; \ + (list)->tail = &(list)->head; /** - * A singly-linked list. + * Wraps a group of statements in a block. */ -struct slist { - struct slink *head; - struct slink **tail; -}; - -/** Initialize an empty list. */ -void slist_init(struct slist *list); - -/** Check if a list is empty. */ -bool slist_is_empty(const struct slist *list); - -/** Add an entry at the tail of the list. */ -void slist_append(struct slist *list, struct slink *link); - -/** Add an entry at the head of the list. */ -void slist_prepend(struct slist *list, struct slink *link); - -/** Add an entire list at the tail of the list. */ -void slist_extend(struct slist *dest, struct slist *src); - -/** Remove the head of the list. */ -struct slink *slist_pop(struct slist *list); +#define LIST_BLOCK_(block) do { block } while (0) /** - * Comparison function type for slist_sort(). + * Add an item to the tail of a singly-linked list. * - * @param left - * The left-hand side of the comparison. - * @param right - * The right-hand side of the comparison. - * @param ptr - * An arbitrary pointer passed to slist_sort(). - * @return - * Whether left <= right. + * @param list + * The list to modify. + * @param item + * The item to append. + * @param link (optional) + * If specified, use item->link.next rather than item->next. + * + * --- + * + * We play some tricks with variadic macros to handle the optional parameter: + * + * SLIST_APPEND(list, item) => { + * *list->tail = item; + * list->tail = &item->next; + * } + * + * SLIST_APPEND(list, item, link) => { + * *list->tail = item; + * list->tail = &item->link.next; + * } + * + * The first trick is that + * + * #define SLIST_APPEND(list, item, ...) + * + * won't work because both commas are required (until C23; see N3033). As a + * workaround, we dispatch to another macro and add a trailing comma. + * + * SLIST_APPEND(list, item) => SLIST_APPEND_(list, item, ) + * SLIST_APPEND(list, item, link) => SLIST_APPEND_(list, item, link, ) */ -typedef bool slist_cmp_fn(struct slink *left, struct slink *right, const void *ptr); +#define SLIST_APPEND(list, ...) SLIST_APPEND_(list, __VA_ARGS__, ) -/** Sort a list. */ -void slist_sort(struct slist *list, slist_cmp_fn *cmp_fn, const void *ptr); +/** + * Now we need a way to generate either ->next or ->link.next depending on + * whether the link parameter was passed. The approach is based on + * + * #define FOO(...) BAR(__VA_ARGS__, 1, 2, ) + * #define BAR(x, y, z, ...) z + * + * FOO(a) => 2 + * FOO(a, b) => 1 + * + * The LIST_NEXT_() macro uses this technique: + * + * LIST_NEXT_() => LIST_LINK_(next, ) + * LIST_NEXT_(link, ) => LIST_LINK_(next, link, ) + */ +#define LIST_NEXT_(...) LIST_LINK_(next, __VA_ARGS__) /** - * A doubly-linked list entry. + * LIST_LINK_() dispatches to yet another macro: + * + * LIST_LINK_(next, ) => LIST_LINK__(next, , , . , , ) + * LIST_LINK_(next, link, ) => LIST_LINK__(next, link, , , . , , ) */ -struct link { - struct link *prev; - struct link *next; -}; +#define LIST_LINK_(dir, ...) LIST_LINK__(dir, __VA_ARGS__, , . , , ) -/** Initialize a list entry. */ -void link_init(struct link *link); +/** + * And finally, LIST_LINK__() adds the link and the dot if necessary. + * + * dir link blank ignored dot + * v v v v v + * LIST_LINK__(next, , , . , , ) => next + * LIST_LINK__(next, link, , , . , , ) => link . next + * ^ ^ ^ ^ ^ + * dir link blank ignored dot + */ +#define LIST_LINK__(dir, link, blank, ignored, dot, ...) link dot dir /** - * A doubly-linked list. + * SLIST_APPEND_() uses LIST_NEXT_() to generate the right name for the list + * link, and finally delegates to the actual implementation. + * + * SLIST_APPEND_(list, item, ) => SLIST_APPEND__((list), (item), next) + * SLIST_APPEND_(list, item, link, ) => SLIST_APPEND__((list), (item), link.next) */ -struct list { - struct link *head; - struct link *tail; -}; +#define SLIST_APPEND_(list, item, ...) \ + LIST_BLOCK_(SLIST_APPEND__((list), (item), LIST_NEXT_(__VA_ARGS__))) -/** Initialize an empty list. */ -void list_init(struct list *list); +#define SLIST_APPEND__(list, item, next) \ + *list->tail = item; \ + list->tail = &item->next; -/** Check if a list is empty. */ -bool list_is_empty(const struct list *list); +/** + * Add an item to the head of a singly-linked list. + * + * @param list + * The list to modify. + * @param item + * The item to prepend. + * @param link (optional) + * If specified, use item->link.next rather than item->next. + */ +#define SLIST_PREPEND(list, ...) SLIST_PREPEND_(list, __VA_ARGS__, ) -/** Add an entry at the tail of the list. */ -void list_append(struct list *list, struct link *link); +#define SLIST_PREPEND_(list, item, ...) \ + LIST_BLOCK_(SLIST_PREPEND__((list), (item), LIST_NEXT_(__VA_ARGS__))) -/** Add an entry at the head of the list. */ -void list_prepend(struct list *list, struct link *link); +#define SLIST_PREPEND__(list, item, next) \ + list->tail = list->head ? list->tail : &item->next; \ + item->next = list->head; \ + list->head = item; -/** Insert an entry after the target entry. */ -void list_insert_after(struct list *list, struct link *target, struct link *link); +/** + * Add an entire singly-linked list to the tail of another. + * + * @param dest + * The destination list. + * @param src + * The source list. + */ +#define SLIST_EXTEND(dest, src) \ + LIST_BLOCK_(SLIST_EXTEND_((dest), (src))) -/** Remove an entry from a list. */ -void list_remove(struct list *list, struct link *link); +#define SLIST_EXTEND_(dest, src) \ + if (src->head) { \ + *dest->tail = src->head; \ + dest->tail = src->tail; \ + SLIST_INIT(src); \ + } -/** Remove the head of the list. */ -struct link *list_pop(struct list *list); +/** + * Pop the head off a singly-linked list. + * + * @param list + * The list to pop from. + * @param link (optional) + * If specified, use head->link.next rather than head->next. + */ +#define SLIST_POP(...) SLIST_POP_(__VA_ARGS__, ) -/** Check if a link is attached to a list. */ -bool list_attached(const struct list *list, const struct link *link); +#define SLIST_POP_(list, ...) \ + LIST_BLOCK_(SLIST_POP__((list), LIST_NEXT_(__VA_ARGS__))) -// LIST_ITEM() helper -#define LIST_ITEM_IMPL(type, entry, member, ...) \ - BFS_CONTAINER_OF(entry, type, member) +#define SLIST_POP__(list, next) \ + void *_next = (void *)list->head->next; \ + list->head->next = NULL; \ + list->head = _next; \ + list->tail = list->head ? list->tail : &list->head; /** - * Convert a list entry to its container. + * Initialize a doubly-linked list. * - * @param type - * The type of the list entries. - * @param entry - * The list entry to convert. - * @param member - * The name of the list link field (default: link). - * @return - * The item that contains the given entry. + * @param list + * The list to initialize. */ -#define LIST_ITEM(...) \ - LIST_ITEM_IMPL(__VA_ARGS__, link,) +#define LIST_INIT(list) \ + LIST_BLOCK_(LIST_INIT_((list))) -// LIST_NEXT() helper -#define LIST_NEXT_IMPL(type, entry, member, ...) \ - LIST_ITEM(type, (entry)->member.next, member) +#define LIST_INIT_(list) \ + list->head = list->tail = NULL; /** - * Get the next item in a list. - * - * @param type - * The type of the list entries. - * @param entry - * The current entry. - * @param member - * The name of the list link field (default: link). - * @return - * The next item in the list. + * LIST_PREV_() => prev + * LIST_PREV_(link, ) => link.prev */ -#define LIST_NEXT(...) \ - LIST_NEXT_IMPL(__VA_ARGS__, link,) - -// LIST_PREV() helper -#define LIST_PREV_IMPL(type, entry, member, ...) \ - LIST_ITEM(type, (entry)->member.prev, member) +#define LIST_PREV_(...) LIST_LINK_(prev, __VA_ARGS__) /** - * Get the previous entry in a list. + * Add an item to the tail of a doubly-linked list. * - * @param type - * The type of the list entries. - * @param entry - * The current entry. - * @param member - * The name of the list link field (default: link). - * @return - * The previous item in the list. + * @param list + * The list to modify. + * @param item + * The item to append. + * @param link (optional) + * If specified, use item->link.{prev,next} rather than item->{prev,next}. */ -#define LIST_PREV(...) \ - LIST_PREV_IMPL(__VA_ARGS__, link,) +#define LIST_APPEND(list, ...) LIST_INSERT(list, (list)->tail, __VA_ARGS__) -// Helper for LIST_FOR_EACH_*() -#define LIST_FOR_EACH_IMPL(entry, type, i, member, ...) \ - for (type *_next, *i = LIST_ITEM(type, entry, member); \ - i && (_next = LIST_NEXT(type, i, member), true); \ - i = _next) +/** + * Add an item to the head of a doubly-linked list. + * + * @param list + * The list to modify. + * @param item + * The item to prepend. + * @param link (optional) + * If specified, use item->link.{prev,next} rather than item->{prev,next}. + */ +#define LIST_PREPEND(list, ...) LIST_INSERT(list, NULL, __VA_ARGS__) /** - * Iterate over a list from the given entry. + * Insert into a doubly-linked list after the given cursor. * - * @param entry - * The entry to start from. - * @param type - * The type of the list entries. - * @param i - * The name of the loop variable, declared as type *i. - * @param member - * The name of the list link field (default: link). + * @param list + * The list to initialize. + * @param cursor + * Insert after this element. + * @param item + * The item to insert. + * @param link (optional) + * If specified, use item->link.{prev,next} rather than item->{prev,next}. */ -#define LIST_FOR_EACH_FROM(...) \ - LIST_FOR_EACH_IMPL(__VA_ARGS__, link,) +#define LIST_INSERT(list, cursor, ...) LIST_INSERT_(list, cursor, __VA_ARGS__, ) + +#define LIST_INSERT_(list, cursor, item, ...) \ + LIST_BLOCK_(LIST_INSERT__((list), (cursor), (item), LIST_PREV_(__VA_ARGS__), LIST_NEXT_(__VA_ARGS__))) + +#define LIST_INSERT__(list, cursor, item, prev, next) \ + item->prev = cursor; \ + item->next = cursor ? cursor->next : list->head; \ + *(item->prev ? &item->prev->next : &list->head) = item; \ + *(item->next ? &item->next->prev : &list->tail) = item; /** - * Iterate over a list. + * Remove an item from a doubly-linked list. * * @param list - * The list to iterate over. - * @param type - * The type of the list entries. - * @param i - * The name of the loop variable, declared as type *i. - * @param member - * The name of the list link field (default: link). + * The list to modify. + * @param item + * The item to remove. + * @param link (optional) + * If specified, use item->link.{prev,next} rather than item->{prev,next}. */ -#define LIST_FOR_EACH(list, ...) \ - LIST_FOR_EACH_FROM((list)->head, __VA_ARGS__) +#define LIST_REMOVE(list, ...) LIST_REMOVE_(list, __VA_ARGS__, ) -// Pop from a list or slist -#define LIST_POP(l) _Generic((l), \ - struct list *: list_pop((struct list *)l), \ - struct slist *: slist_pop((struct slist *)l)) +#define LIST_REMOVE_(list, item, ...) \ + LIST_BLOCK_(LIST_REMOVE__((list), (item), LIST_PREV_(__VA_ARGS__), LIST_NEXT_(__VA_ARGS__))) -// Helper for LIST_DRAIN() -#define LIST_DRAIN_IMPL(list, type, i, member, ...) \ - for (type *i; (i = LIST_ITEM(type, LIST_POP(list), member));) +#define LIST_REMOVE__(list, item, prev, next) \ + *(item->prev ? &item->prev->next : &list->head) = item->next; \ + *(item->next ? &item->next->prev : &list->tail) = item->prev; \ + item->prev = item->next = NULL; /** - * Drain the entries from a list. + * Check if an item is attached to a doubly-linked list. * * @param list - * The list to drain. - * @param type - * The type of the list entries. - * @param i - * The name of the loop variable, declared as type *i. - * @param member - * The name of the list link field (default: link). - */ -#define LIST_DRAIN(...) \ - LIST_DRAIN_IMPL(__VA_ARGS__, link,) + * The list to check. + * @param item + * The item to check. + * @param link (optional) + * If specified, use item->link.{prev,next} rather than item->{prev,next}. + * @return + * Whether the item is attached to the list. + */ +#define LIST_ATTACHED(list, ...) LIST_ATTACHED_(list, __VA_ARGS__, ) + +#define LIST_ATTACHED_(list, item, ...) \ + LIST_ATTACHED__((list), (item), LIST_PREV_(__VA_ARGS__), LIST_NEXT_(__VA_ARGS__)) + +#define LIST_ATTACHED__(list, item, prev, next) \ + (item->prev || item->next || list->head == item || list->tail == item) #endif // BFS_LIST_H |