2 local function _remove(list, m)
9 if list._tail == m then
12 if list._head == m then
15 list._count = list._count - 1;
18 local function _insert(list, m)
22 m.prev, m.next = nil, list._head;
24 if not list._tail then
27 list._count = list._count + 1;
30 local cache_methods = {};
31 local cache_mt = { __index = cache_methods };
33 function cache_methods:set(k, v)
34 local m = self._data[k];
38 -- Bump to head of list
53 -- Check whether we need to remove oldest k/v
54 local on_evict, evicted_key, evicted_value;
55 if self._count == self.size then
56 local tail = self._tail;
57 on_evict, evicted_key, evicted_value = self._on_evict, tail.key, tail.value;
59 self._data[evicted_key] = nil;
62 m = { key = k, value = v, prev = nil, next = nil };
65 if on_evict and evicted_key then
66 on_evict(evicted_key, evicted_value, self);
71 function cache_methods:get(k)
72 local m = self._data[k];
79 function cache_methods:items()
85 local k, v = m.key, m.value;
91 function cache_methods:count()
95 function cache_methods:head()
96 local head = self._head;
97 if not head then return nil, nil; end
98 return head.key, head.value;
101 function cache_methods:tail()
102 local tail = self._tail;
103 if not tail then return nil, nil; end
104 return tail.key, tail.value;
107 local function new(size, on_evict)
108 size = assert(tonumber(size), "cache size must be a number");
109 size = math.floor(size);
110 assert(size > 0, "cache size must be greater than zero");
112 return setmetatable({ _data = data, _count = 0, size = size, _head = nil, _tail = nil, _on_evict = on_evict }, cache_mt);