-- Reads a dotted key from t
local function read(t, key)
   local b,s,l = string.byte,string.sub,1
   for i=1, key:len()+1 do
      local c = b(key, i)
      if c==nil or c==46 then
	 if l==i then
	    error( "Invalid key: [" .. tostring(key) .. "] at character position: " .. tostring(l) )
	 end
	 t,l = type(t)~="table" and nil or t[s(key, l, i-1)],i+1
      end
   end
   return t
end

local t = { one = { two = "12", t = true, f = false } }
assert( read(t, "one.two") == "12" )
assert( read(t, "one.t") == true )
assert( read(t, "one.t1") == nil )
assert( read(t, "one.f") == false )
assert( read(t, "one.f1") == nil )
assert( type(read(t, "one"))=="table"  )
--assert( read(read(t,"one1",read(t,"one")), "two") == "12")
print( read(t,"one.two"))
print( read(t,"blah"))

-- Evals a boolean "AND" expression of dotted keys
local function eval(t, expr)
   local b,s,r,l,plus = string.byte,string.sub,read
   for i=1, expr:len()+1 do
      local c = b(expr, i)
      if c==nil or c==43 or c==45 then
	 if l==i or c==nil and l==nil then
	    error( "Invalid expression" )
	 end
	 if l~=nil then
	    local k = s(expr, l, i-1)
	    local v = r(t, k)
	    local f = v==plus
	    if c==nil or not(f) then
	       print(k,v,f,plus)
	       return f
	    end
	 end
	 plus,l = c==43,i+1
      end
   end
   assert(nil)
end

local f = { a = { b = { c = false } } }
assert( eval(f, "-a.b.c") == false )
assert( eval(f, "+a.b.c") == true )

-- Splits a single line into word table. Handles and preserves quotes (' " `)
local function split(l)
   local t,n, b,s, p,q = {},1, string.byte,string.sub
   for i=1, l:len() do
      local c = b(l, i)
      if not(q) then
	 if c==9 or c==32 then
	    if p then
	       t[n],n, p = s(l, p, i - 1),n + 1
	    end
	 else
	    q = (c==34 or c==39 or c==96) and c
	    p = p or i
	 end
      elseif q==c then
	 q = nil
      end
   end
   t[n] = p and s(l,p)
   return t
end

-- Splits each line from lines
-- Then finds all boolean expressions
-- And based on them leaves only these lines
local function expand(t, words)
   local more_expr, accepted = true
   local out, b = {}, string.byte
   for i=1, #words do
      local w = words[i]
      local c = b(w)
      if more_expr and (c==43 or c==45) then
	 if not(accepted) then
	    accepted = eval(t,w)
	    print('AA',accepted,w)
	 end
      elseif accepted~=false then
	 out[ #out+1 ] = w
	 more_expr = false
      else
	 break
      end
   end
   return out
end

do
   local t = { debug=false }
   for l in io.lines('z.lib.build') do
   --   print(l)
      print(table.concat(expand(t,split(l)), ' .. '))
   end
end