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package container_lru
import "base:runtime"
import "base:intrinsics"
_ :: runtime
_ :: intrinsics
Node :: struct($Key, $Value: typeid) where intrinsics.type_is_valid_map_key(Key) {
prev, next: ^Node(Key, Value),
key: Key,
value: Value,
}
// Cache is an LRU cache. It automatically removes entries as new entries are
// added if the capacity is reached. Entries are removed based on how recently
// they were used where the oldest entries are removed first.
Cache :: struct($Key, $Value: typeid) where intrinsics.type_is_valid_map_key(Key) {
head: ^Node(Key, Value),
tail: ^Node(Key, Value),
entries: map[Key]^Node(Key, Value),
count: int,
capacity: int,
node_allocator: runtime.Allocator,
on_remove: proc(key: Key, value: Value, user_data: rawptr),
on_remove_user_data: rawptr,
}
// init initializes a Cache
init :: proc(c: ^$C/Cache($Key, $Value), capacity: int, entries_allocator := context.allocator, node_allocator := context.allocator) {
c.entries.allocator = entries_allocator
c.node_allocator = node_allocator
c.capacity = capacity
}
// destroy deinitializes a Cachem
destroy :: proc(c: ^$C/Cache($Key, $Value), call_on_remove: bool) {
clear(c, call_on_remove)
delete(c.entries)
}
// clear the contents of a Cache
clear :: proc(c: ^$C/Cache($Key, $Value), call_on_remove: bool) {
for _, node in c.entries {
if call_on_remove {
_call_on_remove(c, node)
}
free(node, c.node_allocator)
}
runtime.clear(&c.entries)
c.head = nil
c.tail = nil
c.count = 0
}
// set the given key value pair. This operation updates the recent usage of the item.
set :: proc(c: ^$C/Cache($Key, $Value), key: Key, value: Value) -> runtime.Allocator_Error {
if e, ok := c.entries[key]; ok {
e.value = value
_pop_node(c, e)
_push_front_node(c, e)
return nil
}
e : ^Node(Key, Value) = nil
assert(c.count <= c.capacity)
if c.count == c.capacity {
e = c.tail
_remove_node(c, e)
}
else {
c.count += 1
e = new(Node(Key, Value), c.node_allocator) or_return
}
e.key = key
e.value = value
_push_front_node(c, e)
c.entries[key] = e
return nil
}
// get a value from the cache from a given key. This operation updates the usage of the item.
get :: proc(c: ^$C/Cache($Key, $Value), key: Key) -> (value: Value, ok: bool) #optional_ok {
e: ^Node(Key, Value)
e, ok = c.entries[key]
if !ok {
return
}
_pop_node(c, e)
_push_front_node(c, e)
return e.value, true
}
// get_ptr gets the pointer to a value the cache from a given key. This operation updates the usage of the item.
get_ptr :: proc(c: ^$C/Cache($Key, $Value), key: Key) -> (value: ^Value, ok: bool) #optional_ok {
e: ^Node(Key, Value)
e, ok = c.entries[key]
if !ok {
return
}
_pop_node(c, e)
_push_front_node(c, e)
return &e.value, true
}
// peek gets the value from the cache from a given key without updating the recent usage.
peek :: proc(c: ^$C/Cache($Key, $Value), key: Key) -> (value: Value, ok: bool) #optional_ok {
e: ^Node(Key, Value)
e, ok = c.entries[key]
if !ok {
return
}
return e.value, true
}
// exists checks for the existence of a value from a given key without updating the recent usage.
exists :: proc(c: ^$C/Cache($Key, $Value), key: Key) -> bool {
return key in c.entries
}
// remove removes an item from the cache.
remove :: proc(c: ^$C/Cache($Key, $Value), key: Key) -> bool {
e, ok := c.entries[key]
if !ok {
return false
}
_remove_node(c, e)
free(node, c.node_allocator)
c.count -= 1
return true
}
@(private)
_remove_node :: proc(c: ^$C/Cache($Key, $Value), node: ^Node(Key, Value)) {
if c.head == node {
c.head = node.next
}
if c.tail == node {
c.tail = node.prev
}
if node.prev != nil {
node.prev.next = node.next
}
if node.next != nil {
node.next.prev = node.prev
}
node.prev = nil
node.next = nil
delete_key(&c.entries, node.key)
_call_on_remove(c, node)
}
@(private)
_call_on_remove :: proc(c: ^$C/Cache($Key, $Value), node: ^Node(Key, Value)) {
if c.on_remove != nil {
c.on_remove(node.key, node.value, c.on_remove_user_data)
}
}
@(private)
_push_front_node :: proc(c: ^$C/Cache($Key, $Value), e: ^Node(Key, Value)) {
if c.head != nil {
e.next = c.head
e.next.prev = e
}
c.head = e
if c.tail == nil {
c.tail = e
}
e.prev = nil
}
@(private)
_pop_node :: proc(c: ^$C/Cache($Key, $Value), e: ^Node(Key, Value)) {
if e == nil {
return
}
if c.head == e {
c.head = e.next
}
if c.tail == e {
c.tail = e.prev
}
if e.prev != nil {
e.prev.next = e.next
}
if e.next != nil {
e.next.prev = e.prev
}
e.prev = nil
e.next = nil
}
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