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309 rader
9.3 KiB
309 rader
9.3 KiB
-- -----------------------------------------------------------------------------
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-- -- LTN12 - Filters, sources, sinks and pumps.
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-- -- LuaSocket toolkit.
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-- -- Author: Diego Nehab
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-- -----------------------------------------------------------------------------
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-- -----------------------------------------------------------------------------
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-- -- Declare module
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-- -----------------------------------------------------------------------------
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-- local string = require("string")
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-- local table = require("table")
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-- local unpack = unpack or table.unpack
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-- local base = _G
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-- local _M = {}
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-- if module then -- heuristic for exporting a global package table
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-- ltn12 = _M
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-- end
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-- local filter,source,sink,pump = {},{},{},{}
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-- _M.filter = filter
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-- _M.source = source
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-- _M.sink = sink
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-- _M.pump = pump
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-- local unpack = unpack or table.unpack
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-- local select = base.select
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-- -- 2048 seems to be better in windows...
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-- _M.BLOCKSIZE = 2048
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-- _M._VERSION = "LTN12 1.0.3"
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-- -----------------------------------------------------------------------------
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-- -- Filter stuff
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-- -----------------------------------------------------------------------------
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-- -- returns a high level filter that cycles a low-level filter
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-- function filter.cycle(low, ctx, extra)
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-- base.assert(low)
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-- return function(chunk)
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-- local ret
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-- ret, ctx = low(ctx, chunk, extra)
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-- return ret
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-- end
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-- end
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-- -- chains a bunch of filters together
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-- -- (thanks to Wim Couwenberg)
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-- function filter.chain(...)
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-- local arg = {...}
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-- local n = base.select('#',...)
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-- local top, index = 1, 1
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-- local retry = ""
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-- return function(chunk)
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-- retry = chunk and retry
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-- while true do
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-- if index == top then
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-- chunk = arg[index](chunk)
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-- if chunk == "" or top == n then return chunk
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-- elseif chunk then index = index + 1
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-- else
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-- top = top+1
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-- index = top
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-- end
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-- else
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-- chunk = arg[index](chunk or "")
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-- if chunk == "" then
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-- index = index - 1
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-- chunk = retry
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-- elseif chunk then
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-- if index == n then return chunk
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-- else index = index + 1 end
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-- else base.error("filter returned inappropriate nil") end
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-- end
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-- end
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-- end
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-- end
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-- -----------------------------------------------------------------------------
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-- -- Source stuff
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-- -----------------------------------------------------------------------------
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-- -- create an empty source
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-- local function empty()
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-- return nil
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-- end
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-- function source.empty()
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-- return empty
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-- end
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-- -- returns a source that just outputs an error
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-- function source.error(err)
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-- return function()
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-- return nil, err
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-- end
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-- end
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-- -- creates a file source
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-- function source.file(handle, io_err)
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-- if handle then
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-- return function()
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-- local chunk = handle:read(_M.BLOCKSIZE)
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-- if not chunk then handle:close() end
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-- return chunk
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-- end
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-- else return source.error(io_err or "unable to open file") end
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-- end
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-- -- turns a fancy source into a simple source
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-- function source.simplify(src)
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-- base.assert(src)
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-- return function()
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-- local chunk, err_or_new = src()
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-- src = err_or_new or src
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-- if not chunk then return nil, err_or_new
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-- else return chunk end
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-- end
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-- end
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-- -- creates string source
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-- function source.string(s)
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-- if s then
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-- local i = 1
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-- return function()
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-- local chunk = string.sub(s, i, i+_M.BLOCKSIZE-1)
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-- i = i + _M.BLOCKSIZE
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-- if chunk ~= "" then return chunk
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-- else return nil end
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-- end
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-- else return source.empty() end
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-- end
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-- -- creates rewindable source
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-- function source.rewind(src)
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-- base.assert(src)
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-- local t = {}
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-- return function(chunk)
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-- if not chunk then
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-- chunk = table.remove(t)
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-- if not chunk then return src()
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-- else return chunk end
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-- else
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-- table.insert(t, chunk)
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-- end
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-- end
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-- end
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-- -- chains a source with one or several filter(s)
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-- function source.chain(src, f, ...)
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-- if ... then f=filter.chain(f, ...) end
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-- base.assert(src and f)
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-- local last_in, last_out = "", ""
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-- local state = "feeding"
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-- local err
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-- return function()
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-- if not last_out then
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-- base.error('source is empty!', 2)
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-- end
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-- while true do
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-- if state == "feeding" then
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-- last_in, err = src()
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-- if err then return nil, err end
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-- last_out = f(last_in)
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-- if not last_out then
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-- if last_in then
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-- base.error('filter returned inappropriate nil')
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-- else
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-- return nil
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-- end
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-- elseif last_out ~= "" then
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-- state = "eating"
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-- if last_in then last_in = "" end
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-- return last_out
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-- end
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-- else
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-- last_out = f(last_in)
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-- if last_out == "" then
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-- if last_in == "" then
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-- state = "feeding"
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-- else
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-- base.error('filter returned ""')
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-- end
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-- elseif not last_out then
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-- if last_in then
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-- base.error('filter returned inappropriate nil')
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-- else
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-- return nil
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-- end
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-- else
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-- return last_out
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-- end
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-- end
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-- end
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-- end
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-- end
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-- -- creates a source that produces contents of several sources, one after the
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-- -- other, as if they were concatenated
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-- -- (thanks to Wim Couwenberg)
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-- function source.cat(...)
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-- local arg = {...}
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-- local src = table.remove(arg, 1)
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-- return function()
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-- while src do
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-- local chunk, err = src()
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-- if chunk then return chunk end
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-- if err then return nil, err end
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-- src = table.remove(arg, 1)
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-- end
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-- end
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-- end
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-- -----------------------------------------------------------------------------
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-- -- Sink stuff
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-- -----------------------------------------------------------------------------
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-- -- creates a sink that stores into a table
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-- function sink.table(t)
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-- t = t or {}
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-- local f = function(chunk, err)
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-- if chunk then table.insert(t, chunk) end
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-- return 1
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-- end
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-- return f, t
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-- end
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-- -- turns a fancy sink into a simple sink
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-- function sink.simplify(snk)
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-- base.assert(snk)
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-- return function(chunk, err)
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-- local ret, err_or_new = snk(chunk, err)
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-- if not ret then return nil, err_or_new end
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-- snk = err_or_new or snk
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-- return 1
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-- end
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-- end
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-- -- creates a file sink
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-- function sink.file(handle, io_err)
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-- if handle then
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-- return function(chunk, err)
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-- if not chunk then
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-- handle:close()
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-- return 1
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-- else return handle:write(chunk) end
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-- end
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-- else return sink.error(io_err or "unable to open file") end
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-- end
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-- -- creates a sink that discards data
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-- local function null()
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-- return 1
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-- end
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-- function sink.null()
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-- return null
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-- end
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-- -- creates a sink that just returns an error
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-- function sink.error(err)
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-- return function()
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-- return nil, err
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-- end
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-- end
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-- -- chains a sink with one or several filter(s)
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-- function sink.chain(f, snk, ...)
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-- if ... then
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-- local args = { f, snk, ... }
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-- snk = table.remove(args, #args)
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-- f = filter.chain(unpack(args))
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-- end
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-- base.assert(f and snk)
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-- return function(chunk, err)
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-- if chunk ~= "" then
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-- local filtered = f(chunk)
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-- local done = chunk and ""
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-- while true do
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-- local ret, snkerr = snk(filtered, err)
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-- if not ret then return nil, snkerr end
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-- if filtered == done then return 1 end
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-- filtered = f(done)
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-- end
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-- else return 1 end
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-- end
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-- end
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-- -----------------------------------------------------------------------------
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-- -- Pump stuff
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-- -----------------------------------------------------------------------------
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-- -- pumps one chunk from the source to the sink
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-- function pump.step(src, snk)
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-- local chunk, src_err = src()
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-- local ret, snk_err = snk(chunk, src_err)
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-- if chunk and ret then return 1
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-- else return nil, src_err or snk_err end
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-- end
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-- -- pumps all data from a source to a sink, using a step function
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-- function pump.all(src, snk, step)
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-- base.assert(src and snk)
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-- step = step or pump.step
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-- while true do
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-- local ret, err = step(src, snk)
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-- if not ret then
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-- if err then return nil, err
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-- else return 1 end
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-- end
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-- end
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-- end
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-- return _M
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