2 files changed, 60 insertions, 41 deletions
diff --git a/acf/persistence/backends/json.lua b/acf/persistence/backends/json.lua
index 6500d13..299cf72 100644
--- a/acf/persistence/backends/json.lua
+++ b/acf/persistence/backends/json.lua
@@ -6,6 +6,7 @@ See LICENSE file for license details
 module(..., package.seeall)
 
 local pth = require('acf.path')
+local Cache = require('acf.persistence.backends.volatile').backend
 local util = require('acf.persistence.util')
 local copy = require('acf.util').copy
 
@@ -13,13 +14,6 @@ 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()
@@ -57,54 +51,27 @@ function backend:split_path(path)
    end
 end
 
-function backend:_get(path)
+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)
+      self.cache[fpath] = Cache(json.decode(util.read_file(fpath)))
    end
-
-   return res
-end
-
-function backend:get(path)
-   local res = self:_get(path)
-   return type(res) == 'table' and keys(res) or res
+   return self.cache[fpath]:get(jpath)
 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
-
+      local path, tpe, value = unpack(mod)
+      local fpath, jpath = self:split_path(path)
+      self.cache[fpath]:_set(jpath, tpe, value)
       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:write(json.encode(self.cache[path]:_get{}))
       file:close()
    end
 end
diff --git a/acf/persistence/backends/volatile.lua b/acf/persistence/backends/volatile.lua
new file mode 100644
index 0000000..63d7265
--- /dev/null
+++ b/acf/persistence/backends/volatile.lua
@@ -0,0 +1,52 @@
+--[[
+Copyright (c) 2012-2013 Kaarle Ritvanen
+See LICENSE file for license details
+--]]
+
+module(..., package.seeall)
+
+local copy = require('acf.util').copy
+
+
+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(data) self.data = data or {} end
+
+function backend:_get(path)
+   local res = self.data
+   for _, comp in ipairs(path) do
+      if res == nil then return end
+      assert(type(res) == 'table')
+      res = res[tonumber(comp) or comp]
+   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(path, tpe, value)
+   if tpe == 'table' then value = {} end
+
+   if #path == 0 then self.data = value
+
+   else
+      local comps = copy(path)
+      local name = comps[#comps]
+      table.remove(comps)
+      self:_get(comps)[tonumber(name) or name] = value
+   end
+end
+
+function backend:set(mods)
+   for _, mod in ipairs(mods) do self:_set(unpack(mod)) end
+end