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--[[
Copyright (c) 2012 Kaarle Ritvanen
See LICENSE file for license details
--]]
module(..., package.seeall)
local pth = require('acf.path')
local util = require('acf.persistence.util')
local copy = require('acf.util').copy
require 'json'
require 'lfs'
local function keys(tbl)
local res = {}
for k, v in pairs(tbl) do table.insert(res, k) end
return res
end
backend = require('acf.object').class()
function backend:init()
-- TODO cache expiration
self.cache = {}
self.dirty = {}
end
function backend:split_path(path)
local fpath = copy(path)
local jpath = {}
local res
while #fpath > 0 do
local fp = pth.join('/', unpack(fpath))
if self.cache[fp] then return fp, jpath end
table.insert(jpath, 1, fpath[#fpath])
table.remove(fpath)
end
fpath = '/'
while true do
fpath = pth.join(fpath, jpath[1])
table.remove(jpath, 1)
local attrs = lfs.attributes(fpath)
if not attrs or not ({directory=true, file=true})[attrs.mode] then
error('File or directory does not exist: '..fpath)
end
if attrs.mode == 'file' then return fpath, jpath end
assert(#jpath > 0)
end
end
function backend:_get(path)
local fpath, jpath = self:split_path(path)
if not self.cache[fpath] then
self.cache[fpath] = json.decode(util.read_file(fpath))
end
local res = self.cache[fpath]
while #jpath > 0 do
if res == nil then return end
assert(type(res) == 'table')
local next = jpath[1]
res = res[tonumber(next) or next]
table.remove(jpath, 1)
end
return res
end
function backend:get(path)
local res = self:_get(path)
return type(res) == 'table' and keys(res) or res
end
function backend:set(mods)
local dirty = {}
for _, mod in ipairs(mods) do
local p, t, value = unpack(mod)
local fpath, jpath = self:split_path(p)
if t == 'table' then value = {} end
if #jpath == 0 then self.cache[fpath] = value
else
local comps = copy(p)
local name = comps[#comps]
table.remove(comps)
self:_get(comps)[tonumber(name) or name] = value
end
dirty[fpath] = true
end
for path, _ in pairs(dirty) do
local file = util.open_file(path, 'w')
file:write(json.encode(self.cache[path]))
file:close()
end
end
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