util/template.lua

   1
   2 local t_insert = table.insert;
   3 local st = require "util.stanza";
   4 local lxp = require "lxp";
   5 local setmetatable = setmetatable;
   6 local pairs = pairs;
   7 local error = error;
   8 local s_gsub = string.gsub;
   9
  10 local print = print;
  11
  12 module("template")
  13
  14 local function process_stanza(stanza, ops)
  15         -- process attrs
  16         for key, val in pairs(stanza.attr) do
  17                 if val:match("{[^}]*}") then
  18                         t_insert(ops, {stanza.attr, key, val});
  19                 end
  20         end
  21         -- process children
  22         local i = 1;
  23         while i <= #stanza do
  24                 local child = stanza[i];
  25                 if child.name then
  26                         process_stanza(child, ops);
  27                 elseif child:match("{[^}]*}") then -- text
  28                         t_insert(ops, {stanza, i, child});
  29                 end
  30                 i = i + 1;
  31         end
  32 end
  33
  34 local parse_xml = (function()
  35         local ns_prefixes = {
  36                 ["http://www.w3.org/XML/1998/namespace"] = "xml";
  37         };
  38         local ns_separator = "\1";
  39         local ns_pattern = "^([^"..ns_separator.."]*)"..ns_separator.."?(.*)$";
  40         return function(xml)
  41                 local handler = {};
  42                 local stanza = st.stanza("root");
  43                 function handler:StartElement(tagname, attr)
  44                         local curr_ns,name = tagname:match(ns_pattern);
  45                         if name == "" then
  46                                 curr_ns, name = "", curr_ns;
  47                         end
  48                         if curr_ns ~= "" then
  49                                 attr.xmlns = curr_ns;
  50                         end
  51                         for i=1,#attr do
  52                                 local k = attr[i];
  53                                 attr[i] = nil;
  54                                 local ns, nm = k:match(ns_pattern);
  55                                 if nm ~= "" then
  56                                         ns = ns_prefixes[ns];
  57                                         if ns then
  58                                                 attr[ns..":"..nm] = attr[k];
  59                                                 attr[k] = nil;
  60                                         end
  61                                 end
  62                         end
  63                         stanza:tag(name, attr);
  64                 end
  65                 function handler:CharacterData(data)
  66                         data = data:gsub("^%s*", ""):gsub("%s*$", "");
  67                         stanza:text(data);
  68                 end
  69                 function handler:EndElement(tagname)
  70                         stanza:up();
  71                 end
  72                 local parser = lxp.new(handler, "\1");
  73                 local ok, err, line, col = parser:parse(xml);
  74                 if ok then ok, err, line, col = parser:parse(); end
  75                 --parser:close();
  76                 if ok then
  77                         return stanza.tags[1];
  78                 else
  79                         return ok, err.." (line "..line..", col "..col..")";
  80                 end
  81         end;
  82 end)();
  83
  84 local function create_template(text)
  85         local stanza, err = parse_xml(text);
  86         if not stanza then error(err); end
  87         local ops = {};
  88         process_stanza(stanza, ops);
  89         ops.stanza = stanza;
  90
  91         local template = {};
  92         function template.apply(data)
  93                 local newops = st.clone(ops);
  94                 for i=1,#newops do
  95                         local op = newops[i];
  96                         local t, k, v = op[1], op[2], op[3];
  97                         t[k] = s_gsub(v, "{([^}]*)}", data);
  98                 end
  99                 return newops.stanza;
 100         end
 101         return template;
 102 end
 103
 104 local templates = setmetatable({}, { __mode = 'k' });
 105 return function(text)
 106         local template = templates[text];
 107         if not template then
 108                 template = create_template(text);
 109                 templates[text] = template;
 110         end
 111         return template;
 112 end;