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if not ltn12 then error('Requires LTN12 module') end
-- create mime namespace
mime = mime or {}
-- make all module globals fall into mime namespace
setmetatable(mime, { __index = _G })
setfenv(1, mime)
-- encode, decode and wrap algorithm tables
encodet = {}
decodet = {}
wrapt = {}
-- creates a function that chooses a filter by name from a given table
local function choose(table)
return function(name, opt)
local f = table[name or "nil"]
if not f then error("unknown filter (" .. tostring(name) .. ")", 3)
else return f(opt) end
end
end
-- define the encoding filters
encodet['base64'] = function()
return ltn12.filter.cycle(b64, "")
end
encodet['quoted-printable'] = function(mode)
return ltn12.filter.cycle(qp, "",
(mode == "binary") and "=0D=0A" or "\13\10")
end
-- define the decoding filters
decodet['base64'] = function()
return ltn12.filter.cycle(unb64, "")
end
decodet['quoted-printable'] = function()
return ltn12.filter.cycle(unqp, "")
end
-- define the line-wrap filters
wrapt['text'] = function(length)
length = length or 76
return ltn12.filter.cycle(wrp, length, length)
end
wrapt['base64'] = wrapt['text']
wrapt['quoted-printable'] = function()
return ltn12.filter.cycle(qpwrp, 76, 76)
end
-- function that choose the encoding, decoding or wrap algorithm
encode = choose(encodet)
decode = choose(decodet)
-- it's different because there is a default wrap filter
local cwt = choose(wrapt)
function wrap(mode_or_length, length)
if type(mode_or_length) ~= "string" then
length = mode_or_length
mode_or_length = "text"
end
return cwt(mode_or_length, length)
end
-- define the end-of-line normalization filter
function normalize(marker)
return ltn12.filter.cycle(eol, 0, marker)
end
return mime
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