move actual preproc lib into folder rather than symlinking to the version in lib/, a better solution will be considered later

preproc.lua

@@ -1 +0,0 @@
-lib/preproc.lua

preproc.lua

@@ -0,0 +1,69 @@
+local preproc = {}
+preproc.directives = {}
+
+function preproc.parsewords(line) -- string -- table -- Returns a table of words from the string *line*, parsing quotes and escapes.
+ local rt = {""}
+ local escaped, quoted = false, false
+ for c in line:gmatch(".") do
+  if escaped then
+   rt[#rt] = rt[#rt]..c
+  elseif c == '"' or c == "'" then
+   quoted = not quoted
+  elseif c == "\\" then
+   escaped = true
+  elseif c:match("%s") and not quoted and rt[#rt]:len() > 0 then
+   rt[#rt+1] = ""
+  else
+   rt[#rt] = rt[#rt]..c
+  end
+ end
+ return rt
+end
+
+function preproc.line(line) -- string -- -- Returns either a function - which can be called to get lines until it returns nil - or a string from processing *line* using preprocessor directives.
+ if line:match("^%-%-#") then
+  local directive, args = line:match("^%-%-#(%S+)%s(.+)")
+  print(directive,args)
+  local args = preproc.parsewords(args)
+  if preproc.directives[directive] then
+   return preproc.directives[directive](table.unpack(args))
+  else
+   error("unknown preprocessor directive: "..directive)
+  end
+ else
+  return line
+ end
+end
+
+function preproc.preproc(...) -- string -- string -- Returns the output from preprocessing the files listed in *...*.
+ local tA = {...}
+ local output = ""
+ for _,fname in ipairs(tA) do
+  local f,e = io.open(fname)
+  if not f then error("unable to open file "..fname..": "..e) end
+  for line in f:lines() do
+   local r = preproc.line(line)
+   if type(r) == "function" then
+    while true do
+     local rs = r()
+     if not rs then break end
+     output = output .. rs .. "\n"
+    end
+   else
+    output = output .. r .. "\n"
+   end
+  end
+ end
+ return output
+end
+
+preproc.directives.include = preproc.preproc
+
+return setmetatable(preproc,{__call=function(_,...)
+ local tA = {...}
+ local out = table.remove(tA,#tA)
+ local f,e = io.open(out,"wb")
+ if not f then error("unable to open file "..out..": "..e) end
+ f:write(preproc.preproc(table.unpack(tA)))
+ f:close()
+end})