From 3a9b0a22e728d1158efccb7f90e2c8aa05c486ef Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Wed, 27 Apr 2022 14:27:33 +0100
Subject: [PATCH] Add `core:container/intrusive/list`

---
 .../intrusive/list/intrusive_list.odin        | 173 ++++++++++++++++++
 1 file changed, 173 insertions(+)
 create mode 100644 core/container/intrusive/list/intrusive_list.odin

diff --git a/core/container/intrusive/list/intrusive_list.odin b/core/container/intrusive/list/intrusive_list.odin
new file mode 100644
index 000000000..88e21edc5
--- /dev/null
+++ b/core/container/intrusive/list/intrusive_list.odin
@@ -0,0 +1,173 @@
+package container_intrusive_list
+
+import "core:intrinsics"
+
+// An intrusive doubly-linked list
+//
+// As this is an intrusive container, a `Node` must be embedded in your own
+// structure which is conventionally called a "link". The use of `push_front`
+// and `push_back` take the address of this node. Retrieving the data
+// associated with the node requires finding the relative offset of the node
+// of the parent structure. The parent type and field name are given to
+// `iterator_*` procedures, or to the built-in `container_of` procedure.
+//
+// This data structure is two-pointers in size:
+// 	8 bytes on 32-bit platforms and 16 bytes on 64-bit platforms
+List :: struct {
+	head: ^Node,
+	tail: ^Node,
+}
+
+
+Node :: struct {
+	next, prev: ^Node,
+}
+
+push_front :: proc(list: ^List, node: ^Node) {
+	if list.head != nil {
+		list.head.prev = node
+		node.prev, node.next = nil, list.head
+		list.head = node
+	} else {
+		list.head, list.tail = node, node
+		node.prev, node.next = nil, nil
+	}
+}
+
+push_back :: proc(list: ^List, node: ^Node) {
+	if list.tail != nil {
+		list.tail.next = node
+		node.prev, node.next = list.tail, nil
+		list.tail = node
+	} else {
+		list.head, list.tail = node, node
+		node.prev, node.next = nil, nil
+	}
+}
+
+remove :: proc(list: ^List, node: ^Node) {
+	if node != nil {
+		if node.next != nil {
+			node.next.prev = node.prev
+		}
+		if node.prev != nil {
+			node.prev.next = node.next
+		}
+		if list.head == node {
+			list.head = node.next
+		}
+		if list.tail == node {
+			list.tail = node.prev
+		}
+	}
+}
+
+remove_by_proc :: proc(list: ^List, to_erase: proc(^Node) -> bool) {
+	for node := list.head; node != nil; {
+		next := node.next
+		if to_erase(node) {
+			if node.next != nil {
+				node.next.prev = node.prev
+			}
+			if node.prev != nil {
+				node.prev.next = node.next
+			}
+			if list.head == node {
+				list.head = node.next
+			}
+			if list.tail == node {
+				list.tail = node.prev
+			}
+		}
+		node = next
+	}
+}
+
+
+is_empty :: proc(list: ^List) -> bool {
+	return list.head == nil
+}
+
+pop_front :: proc(list: ^List) -> ^Node {
+	link := list.head
+	if link == nil {
+		return nil
+	}
+	if link.next != nil {
+		link.next.prev = link.prev
+	}
+	if link.prev != nil {
+		link.prev.next = link.next
+	}
+	if link == list.head {
+		list.head = link.next
+	}
+	if link == list.tail {
+		list.tail = link.prev
+	}
+	return link
+
+}
+pop_back :: proc(list: ^List) -> ^Node {
+	link := list.tail
+	if link == nil {
+		return nil
+	}
+	if link.next != nil {
+		link.next.prev = link.prev
+	}
+	if link.prev != nil {
+		link.prev.next = link.next
+	}
+	if link == list.head {
+		list.head = link.next
+	}
+	if link == list.tail {
+		list.tail = link.prev
+	}
+	return link
+}
+
+
+Iterator :: struct($T: typeid) {
+	curr:   ^Node,
+	offset: uintptr,
+}
+
+iterator_head :: proc(list: List, $T: typeid, $field_name: string) -> Iterator(T)
+	where intrinsics.type_has_field(T, field_name),
+	      intrinsics.type_field_type(T, field_name) == Node {
+	return {list.head, offset_of_by_string(T, field_name)}
+}
+
+iterator_tail :: proc(list: List, $T: typeid, $field_name: string) -> Iterator(T)
+	where intrinsics.type_has_field(T, field_name),
+	      intrinsics.type_field_type(T, field_name) == Node {
+	return {list.tail, offset_of_by_string(T, field_name)}
+}
+
+iterator_from_node :: proc(node: ^Node, $T: typeid, $field_name: string) -> Iterator(T)
+	where intrinsics.type_has_field(T, field_name),
+	      intrinsics.type_field_type(T, field_name) == Node {
+	return {node, offset_of_by_string(T, field_name)}
+}
+
+iterate_next :: proc(it: ^Iterator($T)) -> (ptr: ^T, ok: bool) {
+	node := it.curr
+	if node == nil {
+		return nil, false
+	}
+	it.curr = node.next
+
+	return (^T)(uintptr(node) - it.offset), true
+}
+
+iterate_prev :: proc(it: ^Iterator($T)) -> (ptr: ^T, ok: bool) {
+	node := it.curr
+	if node == nil {
+		return nil, false
+	}
+	it.curr = node.prev
+
+	return (^T)(uintptr(node) - it.offset), true
+}
\ No newline at end of file