pattern.lua

   1 -- The following junk is for building functions to parse strings for various locales.
   2
   3 local varindex, varswap = 0, {}
   4
   5 local function replacePattern(p)
   6   varindex = varindex + 1
   7   local b, e, i = string.find(p, "(%d-)%$")
   8
   9   if i then
  10     -- String contains an index.
  11     p = string.sub(p, 1, b-1)..string.sub(p, e+1)
  12     i = tonumber(i)
  13   else
  14     -- String doesn't contains an index, assume its index is the position we found it in.
  15     i = varindex
  16   end
  17
  18   varswap[i] = varindex
  19
  20   if p == "d" then return "(%d+)" end
  21   if p == "s" then return "(.-)" end
  22
  23   -- Only know about strings and integers. Other types are broken.
  24   assert(false, "Unknown pattern: %"..p)
  25 end
  26
  27 -- Used to cache results, so we don't produce multiple functions for the same string.
  28 local known_patterns = {}
  29
  30 function QuestHelper:convertPattern(pattern)
  31   local result = known_patterns[pattern]
  32
  33   if result then
  34     return result
  35   end
  36
  37   while(table.remove(varswap)) do end
  38
  39   varindex = 0
  40
  41   local pat = string.format("^%s$", string.gsub(pattern, "%%(.-[%%%a])", replacePattern))
  42
  43   if varindex == 0 then
  44     -- The string doesn't contain any variables.
  45     result = self.nop
  46   else
  47     local func =  "local function parse(input)\n"
  48     local linear = true
  49
  50     for i = 1,varindex do
  51       if varswap[i] ~= i then
  52         linear = false
  53         break
  54       end
  55     end
  56
  57     if linear then
  58       -- All the arguments are in order, we can just return them.
  59       func = func .. string.format("return select(3, string.find(input, %q))", pat)
  60     else
  61       -- The order has been changed, use temporary variables.
  62       for i = 1,varindex do
  63         func = func ..(i==1 and "local " or ", ")..("n"..i)
  64       end
  65
  66       func = func .. string.format(" = select(3, string.find(input, %q))\n", pat)
  67
  68       for i = 1,varindex do
  69         func = func ..(i==1 and "return " or ", ")..(varswap[i] and ("n"..varswap[i]) or "nil")
  70       end
  71     end
  72
  73     func = func .. "\nend\nreturn parse\n"
  74
  75     result = loadstring(func)()
  76   end
  77
  78   known_patterns[pattern] = result
  79   return result
  80 end