mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-05-14 02:22:39 +00:00
134 lines
1.9 KiB
Go
134 lines
1.9 KiB
Go
package structr
|
|
|
|
import (
|
|
"sync"
|
|
"unsafe"
|
|
)
|
|
|
|
var list_pool sync.Pool
|
|
|
|
// elem represents an elem
|
|
// in a doubly-linked list.
|
|
type list_elem struct {
|
|
next *list_elem
|
|
prev *list_elem
|
|
|
|
// data is a ptr to the
|
|
// value this linked list
|
|
// element is embedded-in.
|
|
data unsafe.Pointer
|
|
}
|
|
|
|
// list implements a doubly-linked list, where:
|
|
// - head = index 0 (i.e. the front)
|
|
// - tail = index n-1 (i.e. the back)
|
|
type list struct {
|
|
head *list_elem
|
|
tail *list_elem
|
|
len int
|
|
}
|
|
|
|
func list_acquire() *list {
|
|
// Acquire from pool.
|
|
v := list_pool.Get()
|
|
if v == nil {
|
|
v = new(list)
|
|
}
|
|
|
|
// Cast list value.
|
|
return v.(*list)
|
|
}
|
|
|
|
func list_release(l *list) {
|
|
// Reset list.
|
|
l.head = nil
|
|
l.tail = nil
|
|
l.len = 0
|
|
|
|
// Release to pool.
|
|
list_pool.Put(l)
|
|
}
|
|
|
|
func list_push_front(l *list, elem *list_elem) {
|
|
if l.len == 0 {
|
|
// Set new tail + head
|
|
l.head = elem
|
|
l.tail = elem
|
|
|
|
// Link elem to itself
|
|
elem.next = elem
|
|
elem.prev = elem
|
|
} else {
|
|
oldHead := l.head
|
|
|
|
// Link to old head
|
|
elem.next = oldHead
|
|
oldHead.prev = elem
|
|
|
|
// Link up to tail
|
|
elem.prev = l.tail
|
|
l.tail.next = elem
|
|
|
|
// Set new head
|
|
l.head = elem
|
|
}
|
|
|
|
// Incr count
|
|
l.len++
|
|
}
|
|
|
|
func list_move_front(l *list, elem *list_elem) {
|
|
list_remove(l, elem)
|
|
list_push_front(l, elem)
|
|
}
|
|
|
|
func list_remove(l *list, elem *list_elem) {
|
|
if l.len <= 1 {
|
|
// Drop elem's links
|
|
elem.next = nil
|
|
elem.prev = nil
|
|
|
|
// Only elem in list
|
|
l.head = nil
|
|
l.tail = nil
|
|
l.len = 0
|
|
return
|
|
}
|
|
|
|
// Get surrounding elems
|
|
next := elem.next
|
|
prev := elem.prev
|
|
|
|
// Relink chain
|
|
next.prev = prev
|
|
prev.next = next
|
|
|
|
switch elem {
|
|
// Set new head
|
|
case l.head:
|
|
l.head = next
|
|
|
|
// Set new tail
|
|
case l.tail:
|
|
l.tail = prev
|
|
}
|
|
|
|
// Drop elem's links
|
|
elem.next = nil
|
|
elem.prev = nil
|
|
|
|
// Decr count
|
|
l.len--
|
|
}
|
|
|
|
func list_rangefn(l *list, fn func(*list_elem)) {
|
|
if fn == nil {
|
|
panic("nil fn")
|
|
}
|
|
elem := l.head
|
|
for i := 0; i < l.len; i++ {
|
|
fn(elem)
|
|
elem = elem.next
|
|
}
|
|
}
|