1 files changed, 170 insertions, 0 deletions
diff --git a/src/list.h b/src/list.h
new file mode 100644
index 0000000..1985413
--- /dev/null
+++ b/src/list.h
@@ -0,0 +1,170 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+/**
+ * Intrusive linked lists.
+ */
+
+#ifndef BFS_LIST_H
+#define BFS_LIST_H
+
+#include "config.h"
+#include <stdbool.h>
+
+/**
+ * A singly-linked list entry.
+ */
+struct slink {
+	struct slink *next;
+};
+
+/** Initialize a list entry. */
+void slink_init(struct slink *link);
+
+/**
+ * A singly-linked list.
+ */
+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);
+
+/**
+ * Comparison function type for slist_sort().
+ *
+ * @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.
+ */
+typedef bool slist_cmp_fn(struct slink *left, struct slink *right, const void *ptr);
+
+/** Sort a list. */
+void slist_sort(struct slist *list, slist_cmp_fn *cmp_fn, const void *ptr);
+
+/**
+ * A doubly-linked list entry.
+ */
+struct link {
+	struct link *prev;
+	struct link *next;
+};
+
+/** Initialize a list entry. */
+void link_init(struct link *link);
+
+/**
+ * A doubly-linked list.
+ */
+struct list {
+	struct link *head;
+	struct link *tail;
+};
+
+/** Initialize an empty list. */
+void list_init(struct list *list);
+
+/** Check if a list is empty. */
+bool list_is_empty(const struct list *list);
+
+/** Add an entry at the tail of the list. */
+void list_append(struct list *list, struct link *link);
+
+/** Add an entry at the head of the list. */
+void list_prepend(struct list *list, struct link *link);
+
+/** Insert an entry after the target entry. */
+void list_insert_after(struct list *list, struct link *target, struct link *link);
+
+/** Remove an entry from a list. */
+void list_remove(struct list *list, struct link *link);
+
+/** Remove the head of the list. */
+struct link *list_pop(struct list *list);
+
+/** Check if a link is attached to a list. */
+bool list_attached(const struct list *list, const struct link *link);
+
+// Helper for LIST_FOR_EACH_*()
+#define LIST_FOR_EACH_IMPL(entry, type, i, member, ...) \
+	for (type *_next, *i = BFS_CONTAINER_OF(entry, type, member); \
+	     i && (_next = BFS_CONTAINER_OF(i->member.next, type, member), true); \
+	     i = _next)
+
+/**
+ * Iterate over a list from the given entry.
+ *
+ * @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).
+ */
+#define LIST_FOR_EACH_FROM(...) \
+	LIST_FOR_EACH_IMPL(__VA_ARGS__, link,)
+
+/**
+ * Iterate over a 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).
+ */
+#define LIST_FOR_EACH(list, ...) \
+	LIST_FOR_EACH_FROM((list)->head, __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))
+
+// Helper for LIST_DRAIN()
+#define LIST_DRAIN_IMPL(list, type, i, member, ...) \
+	for (type *i; (i = BFS_CONTAINER_OF(LIST_POP(list), type, member));)
+
+/**
+ * Drain the entries from a 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,)
+
+#endif // BFS_LIST_H