File

+
−
+
−local function _remove(list, m)
+
−	if m.prev then
+
−		m.prev.next = m.next;
+
−	end
+
−	if m.next then
+
−		m.next.prev = m.prev;
+
−	end
+
−	if list._tail == m then
+
−		list._tail = m.prev;
+
−	end
+
−	if list._head == m then
+
−		list._head = m.next;
+
−	end
+
−	list._count = list._count - 1;
+
−end
+
−
+
−local function _insert(list, m)
+
−	if list._head then
+
−		list._head.prev = m;
+
−	end
+
−	m.prev, m.next = nil, list._head;
+
−	list._head = m;
+
−	if not list._tail then
+
−		list._tail = m;
+
−	end
+
−	list._count = list._count + 1;
+
−end
+
−
+
−local cache_methods = {};
+
−local cache_mt = { __name = "cache", __index = cache_methods };
+
−
+
−function cache_methods:set(k, v)
+
−	local m = self._data[k];
+
−	if m then
+
−		-- Key already exists
+
−		if v ~= nil then
+
−			-- Bump to head of list
+
−			_remove(self, m);
+
−			_insert(self, m);
+
−			m.value = v;
+
−		else
+
−			-- Remove from list
+
−			_remove(self, m);
+
−			self._data[k] = nil;
+
−		end
+
−		return true;
+
−	end
+
−	-- New key
+
−	if v == nil then
+
−		return true;
+
−	end
+
−	-- Check whether we need to remove oldest k/v
+
−	if self._count == self.size then
+
−		local tail = self._tail;
+
−		local on_evict, evicted_key, evicted_value = self._on_evict, tail.key, tail.value;
+
−		if on_evict ~= nil and (on_evict == false or on_evict(evicted_key, evicted_value) == false) then
+
−			-- Cache is full, and we're not allowed to evict
+
−			return false;
+
−		end
+
−		_remove(self, tail);
+
−		self._data[evicted_key] = nil;
+
−	end
+
−
+
−	m = { key = k, value = v, prev = nil, next = nil };
+
−	self._data[k] = m;
+
−	_insert(self, m);
+
−	return true;
+
−end
+
−
+
−function cache_methods:get(k)
+
−	local m = self._data[k];
+
−	if m then
+
−		return m.value;
+
−	end
+
−	return nil;
+
−end
+
−
+
−function cache_methods:items()
+
−	local m = self._head;
+
−	return function ()
+
−		if not m then
+
−			return;
+
−		end
+
−		local k, v = m.key, m.value;
+
−		m = m.next;
+
−		return k, v;
+
−	end
+
−end
+
−
+
−function cache_methods:values()
+
−	local m = self._head;
+
−	return function ()
+
−		if not m then
+
−			return;
+
−		end
+
−		local v = m.value;
+
−		m = m.next;
+
−		return v;
+
−	end
+
−end
+
−
+
−function cache_methods:count()
+
−	return self._count;
+
−end
+
−
+
−function cache_methods:head()
+
−	local head = self._head;
+
−	if not head then return nil, nil; end
+
−	return head.key, head.value;
+
−end
+
−
+
−function cache_methods:tail()
+
−	local tail = self._tail;
+
−	if not tail then return nil, nil; end
+
−	return tail.key, tail.value;
+
−end
+
−
+
−function cache_methods:resize(new_size)
+
−	new_size = assert(tonumber(new_size), "cache size must be a number");
+
−	new_size = math.floor(new_size);
+
−	assert(new_size > 0, "cache size must be greater than zero");
+
−	local on_evict = self._on_evict;
+
−	while self._count > new_size do
+
−		local tail = self._tail;
+
−		local evicted_key, evicted_value = tail.key, tail.value;
+
−		if on_evict ~= nil and (on_evict == false or on_evict(evicted_key, evicted_value) == false) then
+
−			-- Cache is full, and we're not allowed to evict
+
−			return false;
+
−		end
+
−		_remove(self, tail);
+
−		self._data[evicted_key] = nil;
+
−	end
+
−	self.size = new_size;
+
−	return true;
+
−end
+
−
+
−function cache_methods:table()
+
−	--luacheck: ignore 212/t
+
−	if not self.proxy_table then
+
−		self.proxy_table = setmetatable({}, {
+
−			__index = function (t, k)
+
−				return self:get(k);
+
−			end;
+
−			__newindex = function (t, k, v)
+
−				if not self:set(k, v) then
+
−					error("failed to insert key into cache - full");
+
−				end
+
−			end;
+
−			__pairs = function (t)
+
−				return self:items();
+
−			end;
+
−			__len = function (t)
+
−				return self:count();
+
−			end;
+
−		});
+
−	end
+
−	return self.proxy_table;
+
−end
+
−
+
−function cache_methods:clear()
+
−	self._data = {};
+
−	self._count = 0;
+
−	self._head = nil;
+
−	self._tail = nil;
+
−end
+
−
+
−local function new(size, on_evict)
+
−	size = assert(tonumber(size), "cache size must be a number");
+
−	size = math.floor(size);
+
−	assert(size > 0, "cache size must be greater than zero");
+
−	local data = {};
+
−	return setmetatable({ _data = data, _count = 0, size = size, _head = nil, _tail = nil, _on_evict = on_evict }, cache_mt);
+
−end
+
−
+
−return {
+
−	new = new;
+
−}