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-- make sure LuaSocket is loaded
if not LUASOCKET_LIBNAME then error('module requires LuaSocket') end
-- get LuaSocket namespace
local socket = _G[LUASOCKET_LIBNAME]
if not socket then error('module requires LuaSocket') end
-- create code namespace inside LuaSocket namespace
local mime = socket.mime or {}
socket.mime = mime
-- make all module globals fall into mime namespace
setmetatable(mime, { __index = _G })
setfenv(1, mime)
-- encode, decode and wrap algorithm tables
local et = {}
local dt = {}
local wt = {}
-- creates a function that chooses an algorithm from a given table
local function choose(table)
return function(method, ...)
local f = table[method or "nil"]
if not f then return nil, "unknown method (" .. tostring(method) .. ")"
else return f(unpack(arg)) end
end
end
-- creates a function that cicles a filter with a given initial
-- context and extra arguments
local function cicle(f, ctx, ...)
return function(chunk)
local ret
ret, ctx = f(ctx, chunk, unpack(arg))
return ret
end
end
-- function that choose the encoding, decoding or wrap algorithm
encode = choose(et)
decode = choose(dt)
wrap = choose(wt)
-- define the encoding algorithms
et['base64'] = function()
return cicle(b64, "")
end
et['quoted-printable'] = function(mode)
return cicle(qp, "", (mode == "binary") and "=0D=0A" or "\13\10")
end
-- define the decoding algorithms
dt['base64'] = function()
return cicle(unb64, "")
end
dt['quoted-printable'] = function()
return cicle(unqp, "")
end
-- define the wrap algorithms
wt['character'] = function(length)
length = length or 76
return cicle(fmt, length, length)
end
wt['base64'] = wt['character']
wt['quoted-printable'] = function(length)
length = length or 76
return cicle(qpfmt, length, length)
end
-- define the end-of-line translation function
function canonic(marker)
return cicle(eol, "", marker)
end
-- chains several filters together
function chain(...)
local layers = table.getn(arg)
return function (chunk)
if not chunk then
local parts = {}
for i = 1, layers do
for j = i, layers do
chunk = arg[j](chunk)
end
table.insert(parts, chunk)
chunk = nil
end
return table.concat(parts)
else
for j = 1, layers do
chunk = arg[j](chunk)
end
return chunk
end
end
end
return code
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