300 lines
8.2 KiB
PHP
300 lines
8.2 KiB
PHP
R"-++**++-(
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-----------------------------------------------------------------------------
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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 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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-- 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 = 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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function source.chain(src, f)
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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 a filter
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function sink.chain(f, snk)
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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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)-++**++-"; |