131 lines
2.2 KiB
Go
131 lines
2.2 KiB
Go
package structr
|
|
|
|
// elem represents an element
|
|
// in a doubly-linked list.
|
|
type elem[T any] struct {
|
|
next *elem[T]
|
|
prev *elem[T]
|
|
Value T
|
|
}
|
|
|
|
// list implements a doubly-linked list, where:
|
|
// - head = index 0 (i.e. the front)
|
|
// - tail = index n-1 (i.e. the back)
|
|
type list[T any] struct {
|
|
head *elem[T]
|
|
tail *elem[T]
|
|
len int
|
|
}
|
|
|
|
func list_acquire[T any](c *Cache[T]) *list[*result[T]] {
|
|
var l *list[*result[T]]
|
|
|
|
if len(c.llsPool) == 0 {
|
|
// Allocate new list.
|
|
l = new(list[*result[T]])
|
|
} else {
|
|
// Pop list from pool slice.
|
|
l = c.llsPool[len(c.llsPool)-1]
|
|
c.llsPool = c.llsPool[:len(c.llsPool)-1]
|
|
}
|
|
|
|
return l
|
|
}
|
|
|
|
func list_release[T any](c *Cache[T], l *list[*result[T]]) {
|
|
// Reset list.
|
|
l.head = nil
|
|
l.tail = nil
|
|
l.len = 0
|
|
|
|
// Release list to memory pool.
|
|
c.llsPool = append(c.llsPool, l)
|
|
}
|
|
|
|
// pushFront pushes new 'elem' to front of list.
|
|
func (l *list[T]) pushFront(elem *elem[T]) {
|
|
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++
|
|
}
|
|
|
|
// moveFront calls remove() on elem, followed by pushFront().
|
|
func (l *list[T]) moveFront(elem *elem[T]) {
|
|
l.remove(elem)
|
|
l.pushFront(elem)
|
|
}
|
|
|
|
// remove removes the 'elem' from the list.
|
|
func (l *list[T]) remove(elem *elem[T]) {
|
|
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--
|
|
}
|
|
|
|
// rangefn ranges all the elements in the list, passing each to fn.
|
|
func (l *list[T]) rangefn(fn func(*elem[T])) {
|
|
if fn == nil {
|
|
panic("nil fn")
|
|
}
|
|
elem := l.head
|
|
for i := 0; i < l.len; i++ {
|
|
fn(elem)
|
|
elem = elem.next
|
|
}
|
|
}
|