53 lines
1.6 KiB
Lua
53 lines
1.6 KiB
Lua
---------------------------------------------------------------------------
|
|
-- @author Uli Schlachter
|
|
-- @copyright 2015 Uli Schlachter
|
|
-- @release @AWESOME_VERSION@
|
|
-- @classmod gears.cache
|
|
---------------------------------------------------------------------------
|
|
|
|
local select = select
|
|
local setmetatable = setmetatable
|
|
local unpack = unpack or table.unpack -- luacheck: globals unpack (compatibility with Lua 5.1)
|
|
|
|
local cache = {}
|
|
|
|
--- Get an entry from the cache, creating it if it's missing.
|
|
-- @param ... Arguments for the creation callback. These are checked against the
|
|
-- cache contents for equality.
|
|
-- @return The entry from the cache
|
|
function cache:get(...)
|
|
local result = self._cache
|
|
for i = 1, select("#", ...) do
|
|
local arg = select(i, ...)
|
|
local next = result[arg]
|
|
if not next then
|
|
next = {}
|
|
result[arg] = next
|
|
end
|
|
result = next
|
|
end
|
|
local ret = result._entry
|
|
if not ret then
|
|
ret = { self._creation_cb(...) }
|
|
result._entry = ret
|
|
end
|
|
return unpack(ret)
|
|
end
|
|
|
|
--- Create a new cache object. A cache keeps some data that can be
|
|
-- garbage-collected at any time, but might be useful to keep.
|
|
-- @param creation_cb Callback that is used for creating missing cache entries.
|
|
-- @return A new cache object.
|
|
function cache.new(creation_cb)
|
|
return setmetatable({
|
|
_cache = setmetatable({}, { __mode = "v" }),
|
|
_creation_cb = creation_cb
|
|
}, {
|
|
__index = cache
|
|
})
|
|
end
|
|
|
|
return setmetatable(cache, { __call = function(_, ...) return cache.new(...) end })
|
|
|
|
-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80
|