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--[[--------------------------------------------------------------------
lzio.lua
Lua 5 buffered streams in Lua
This file is part of Yueliang.
Copyright (c) 2005-2006 Kein-Hong Man <khman@users.sf.net>
The COPYRIGHT file describes the conditions
under which this software may be distributed.
See the ChangeLog for more information.
----------------------------------------------------------------------]]
--[[--------------------------------------------------------------------
-- Notes:
-- *
----------------------------------------------------------------------]]
--[[--------------------------------------------------------------------
-- local zio_init = require("lzio.lua")
-- local z = zio_init("@<filename>")
-- local z = zio_init("<string>")
-- z:getc()
-- * get next character from input stream
-- z:fill()
-- * fills an empty stream buffer
-- z.name
-- * name of the chunk, "@<filename>" or "=string"
----------------------------------------------------------------------]]
--[[--------------------------------------------------------------------
-- Format of z structure (ZIO)
-- z.n -- bytes still unread
-- z.p -- last read position in buffer
-- z.reader -- chunk reader function
-- z.data -- data buffer
-- z.name -- name of stream
----------------------------------------------------------------------]]
return
function(buff)
--[[--------------------------------------------------------------------
-- initialize reader
-- * reader should return a string, or nil if nothing else to parse
----------------------------------------------------------------------]]
local reader
local z = {}
if string.sub(buff, 1, 1) == "@" then
----------------------------------------------------------------
-- create a chunk reader function from a source file
----------------------------------------------------------------
z.name = buff
local BUFFERSIZE = 512
local h = io.open(string.sub(buff, 2), "r")
if not h then return nil end
reader = function()
if not h or io.type(h) == "closed file" then return nil end
local buff = h:read(BUFFERSIZE)
if not buff then h:close(); h = nil end
return buff
end
else
----------------------------------------------------------------
-- create a chunk reader function from a source string
----------------------------------------------------------------
z.name = "=string"
reader = function()
if not buff then return nil end
local data = buff
buff = nil
return data
end
end
--[[--------------------------------------------------------------------
-- fills an empty stream buffer, returns first character
----------------------------------------------------------------------]]
function z:fill()
local data = z.reader()
z.data = data
if not data or data == "" then return "EOZ" end
z.n, z.p = string.len(data) - 1, 1
return string.sub(data, 1, 1)
end
--[[--------------------------------------------------------------------
-- get next character, fills buffer if characters needed
----------------------------------------------------------------------]]
function z:getc()
local n, p = z.n, z.p + 1
if n > 0 then
z.n, z.p = n - 1, p
return string.sub(z.data, p, p)
else
return self:fill()
end
end
--[[--------------------------------------------------------------------
-- initialize input stream object
----------------------------------------------------------------------]]
if not reader then return end
z.reader = reader
z.data = ""
z.n, z.p = 0, 0
return z
--[[------------------------------------------------------------------]]
end
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