modules/base/luasrc/template.lua

   1 --[[
   2 LuCI - Template Parser
   3
   4 Description:
   5 A template parser supporting includes, translations, Lua code blocks
   6 and more. It can be used either as a compiler or as an interpreter.
   7
   8 FileId: $Id$
   9
  10 License:
  11 Copyright 2008 Steven Barth <steven@midlink.org>
  12
  13 Licensed under the Apache License, Version 2.0 (the "License");
  14 you may not use this file except in compliance with the License.
  15 You may obtain a copy of the License at
  16
  17         http://www.apache.org/licenses/LICENSE-2.0
  18
  19 Unless required by applicable law or agreed to in writing, software
  20 distributed under the License is distributed on an "AS IS" BASIS,
  21 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  22 See the License for the specific language governing permissions and
  23 limitations under the License.
  24
  25 ]]--
  26
  27 local util = require "luci.util"
  28 local config = require "luci.config"
  29 local tparser = require "luci.template.parser"
  30
  31 local tostring, pairs, loadstring = tostring, pairs, loadstring
  32 local setmetatable, loadfile = setmetatable, loadfile
  33 local getfenv, setfenv, rawget = getfenv, setfenv, rawget
  34 local assert, type, error = assert, type, error
  35
  36 --- LuCI template library.
  37 module "luci.template"
  38
  39 config.template = config.template or {}
  40 viewdir = config.template.viewdir or util.libpath() .. "/view"
  41
  42
  43 -- Define the namespace for template modules
  44 context = util.threadlocal()
  45
  46 --- Render a certain template.
  47 -- @param name          Template name
  48 -- @param scope         Scope to assign to template (optional)
  49 function render(name, scope)
  50         return Template(name):render(scope or getfenv(2))
  51 end
  52
  53 --- Render a template from a string.
  54 -- @param template      Template string
  55 -- @param scope         Scope to assign to template (optional)
  56 function render_string(template, scope)
  57         return Template(nil, template):render(scope or getfenv(2))
  58 end
  59
  60
  61 -- Template class
  62 Template = util.class()
  63
  64 -- Shared template cache to store templates in to avoid unnecessary reloading
  65 Template.cache = setmetatable({}, {__mode = "v"})
  66
  67
  68 -- Constructor - Reads and compiles the template on-demand
  69 function Template.__init__(self, name, template)
  70         if name then
  71                 self.template = self.cache[name]
  72                 self.name = name
  73         else
  74                 self.name = "[string]"
  75         end
  76
  77         -- Create a new namespace for this template
  78         self.viewns = context.viewns
  79
  80         -- If we have a cached template, skip compiling and loading
  81         if not self.template then
  82
  83                 -- Compile template
  84                 local err
  85                 local sourcefile
  86
  87                 if name then
  88                         sourcefile = viewdir .. "/" .. name .. ".htm"
  89                         self.template, _, err = tparser.parse(sourcefile)
  90                 else
  91                         sourcefile = "[string]"
  92                         self.template, _, err = tparser.parse_string(template)
  93                 end
  94
  95                 -- If we have no valid template throw error, otherwise cache the template
  96                 if not self.template then
  97                         error("Failed to load template '" .. name .. "'.\n" ..
  98                               "Error while parsing template '" .. sourcefile .. "':\n" ..
  99                               (err or "Unknown syntax error"))
 100                 elseif name then
 101                         self.cache[name] = self.template
 102                 end
 103         end
 104 end
 105
 106
 107 -- Renders a template
 108 function Template.render(self, scope)
 109         scope = scope or getfenv(2)
 110
 111         -- Put our predefined objects in the scope of the template
 112         setfenv(self.template, setmetatable({}, {__index =
 113                 function(tbl, key)
 114                         return rawget(tbl, key) or self.viewns[key] or scope[key]
 115                 end}))
 116
 117         -- Now finally render the thing
 118         local stat, err = util.copcall(self.template)
 119         if not stat then
 120                 error("Failed to execute template '" .. self.name .. "'.\n" ..
 121                       "A runtime error occured: " .. tostring(err or "(nil)"))
 122         end
 123 end