--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ltn12.lua	Tue Aug 26 18:40:01 2008 -0700
@@ -0,0 +1,292 @@
+-----------------------------------------------------------------------------
+-- LTN12 - Filters, sources, sinks and pumps.
+-- LuaSocket toolkit.
+-- Author: Diego Nehab
+-- RCS ID: $Id: ltn12.lua,v 1.31 2006/04/03 04:45:42 diego Exp $
+-----------------------------------------------------------------------------
+
+-----------------------------------------------------------------------------
+-- Declare module
+-----------------------------------------------------------------------------
+local string = require("string")
+local table = require("table")
+local base = _G
+module("ltn12")
+
+filter = {}
+source = {}
+sink = {}
+pump = {}
+
+-- 2048 seems to be better in windows...
+BLOCKSIZE = 2048
+_VERSION = "LTN12 1.0.1"
+
+-----------------------------------------------------------------------------
+-- 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 n = table.getn(arg)
+    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(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+BLOCKSIZE-1)
+            i = i + 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
+
+function source.chain(src, f)
+    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 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 a filter
+function sink.chain(f, snk)
+    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
+