Edit file

File name : ltn12.lua

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

Save