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 if self._count == self.size then
55 local tail = self._tail;
56 local on_evict, evicted_key, evicted_value = self._on_evict, tail.key, tail.value;
57 if on_evict ~= nil and (on_evict == false or on_evict(evicted_key, evicted_value) == false) then
58 -- Cache is full, and we're not allowed to evict
62 self._data[evicted_key] = nil;
65 m = { key = k, value = v, prev = nil, next = nil };
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:values()
103 function cache_methods:count()
107 function cache_methods:head()
108 local head = self._head;
109 if not head then return nil, nil; end
110 return head.key, head.value;
113 function cache_methods:tail()
114 local tail = self._tail;
115 if not tail then return nil, nil; end
116 return tail.key, tail.value;
119 local function new(size, on_evict)
120 size = assert(tonumber(size), "cache size must be a number");
121 size = math.floor(size);
122 assert(size > 0, "cache size must be greater than zero");
124 return setmetatable({ _data = data, _count = 0, size = size, _head = nil, _tail = nil, _on_evict = on_evict }, cache_mt);