local rawget, rawset, setmetatable = rawget, rawset, setmetatable local str_lower = string.lower local _M = { _VERSION = '0.12', } -- Returns an empty headers table with internalised case normalisation. function _M.new() local mt = { normalised = {}, } mt.__index = function(t, k) return rawget(t, mt.normalised[str_lower(k)]) end mt.__newindex = function(t, k, v) local k_normalised = str_lower(k) -- First time seeing this header field? if not mt.normalised[k_normalised] then -- Create a lowercased entry in the metatable proxy, with the value -- of the given field case mt.normalised[k_normalised] = k -- Set the header using the given field case rawset(t, k, v) else -- We're being updated just with a different field case. Use the -- normalised metatable proxy to give us the original key case, and -- perorm a rawset() to update the value. rawset(t, mt.normalised[k_normalised], v) end end return setmetatable({}, mt) end return _M