1 files changed, 153 insertions, 0 deletions
diff --git a/acf2/persistence/backends/augeas.lua b/acf2/persistence/backends/augeas.lua
new file mode 100644
index 0000000..010a52b
--- /dev/null
+++ b/acf2/persistence/backends/augeas.lua
@@ -0,0 +1,153 @@
+--[[
+Copyright (c) 2012-2013 Kaarle Ritvanen
+See LICENSE file for license details
+--]]
+
+local topology = require('acf2.model.root').topology
+local pth = require('acf2.path')
+
+local util = require('acf2.util')
+local copy = util.copy
+
+
+local function aug_path(path) return pth.join('/files', unpack(path)) end
+
+local function strip_name(name)
+   return type(name) == 'string' and name:match('^[^][/=)%s]+') or name
+end
+
+local function ipath(path, index) return path..'['..index..']' end
+
+
+local backend = require('acf2.object').class()
+
+function backend:init() self.aug = require('augeas').init() end
+
+function backend:find(path, leaf)
+   util.map(
+      function(comp)
+	 assert(
+	    comp == strip_name(comp) and (
+	       type(comp) == 'number' or not comp:match('^%.+$')
+	    )
+	 )
+      end,
+      path
+   )
+   local res = aug_path(path)
+
+   if #self.aug:match(res) == 0 and #path > 1 and leaf then
+      local index = path[#path]
+      if type(index) == 'number' then
+	 local ppath = copy(path)
+	 table.remove(ppath)
+	 ppath = aug_path(ppath)
+
+	 if #self.aug:match(ppath) > 0 and #self.aug:match(
+	    ppath..'/*'
+	 ) == 0 then
+	    return ipath(ppath, index), ppath, index
+	 end
+      end
+   end
+
+   return res
+end
+
+function backend:get(path, top)
+   local tpe = top and top.type
+   local leaf = tpe and tpe ~= 'table'
+   local apath, mvpath = self:find(path, leaf or not tpe)
+
+   local matches = self.aug:match(apath)
+   if mvpath then
+      assert(#matches < 2)
+      leaf = true
+   end
+
+   if #matches == 0 then return end
+
+   if #matches > 1 then
+      assert(not leaf)
+      local res = {}
+      path = copy(path)
+      for i, _ in ipairs(matches) do
+	 table.insert(path, i)
+	 if self:get(path) then table.insert(res, i) end
+	 table.remove(path)
+      end
+      return res
+   end
+
+   local value = self.aug:get(matches[1])
+   if value then return tpe == 'table' and {1} or value end
+   if leaf then return end
+
+   local names = {}
+   for _, child in ipairs(self.aug:match(apath..'/*')) do
+      names[strip_name(pth.name(child))] = true
+   end
+   return util.keys(names)
+end
+
+function backend:set(mods)
+   local gcpaths = {}
+
+   for _, mod in ipairs(mods) do
+      local path, value = unpack(mod)
+
+      local delete = value == nil
+      self.aug:rm(aug_path(path)..(delete and '' or '/*'))
+
+      local apath, mvpath, index = self:find(path, type(value) ~= 'table')
+      local mpath = mvpath or apath
+
+      if not delete then
+	 if #self.aug:match(mpath) == 0 then
+
+	    local function order(path)
+	       return topology('/augeas'..path).order
+	    end
+	    local ord = order(pth.join('/', unpack(path)))
+
+	    for _, sibling in ipairs(self.aug:match(pth.parent(mpath)..'/*')) do
+	       if order(strip_name(sibling):sub(7, -1)) > ord then
+		  self.aug:insert(sibling, pth.name(mpath), true)
+		  break
+	       end
+	    end
+	 end
+
+	 if mvpath then
+	    local size = #self.aug:match(mvpath)
+	    while size < index do
+	       self.aug:insert(ipath(mvpath, size), pth.name(mvpath))
+	       size = size + 1
+	    end
+	 end
+      end
+
+      if type(value) == 'table' then value = nil end
+      if not delete or mvpath then self.aug:set(apath, value)
+      elseif apath > '/' then apath = pth.parent(apath) end
+
+      if delete or value == '' then gcpaths[mpath] = true end
+   end
+
+   local function gc(path)
+      if path == '/' or #self.aug:match(path..'/*') > 0 then return end
+      if self.aug:rm(path.."[. = '']") > 0 then gc(pth.parent(path)) end
+   end
+   for p, _ in pairs(gcpaths) do gc(p) end
+
+   if self.aug:save() ~= 0 then
+      print('Augeas save failed')
+      for _, ep in ipairs(self.aug:match('/augeas//error')) do
+	 print(ep, self.aug:get(ep))
+      end
+      assert(false)
+   end
+end
+
+
+return backend