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--[[--------------------------------------------------------------------
lzio.lua
Lua 5 buffered streams in Lua
This file is part of Yueliang.
Copyright (c) 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:
-- * this is a line-based input streamer for the MK4 lexer
-- * all EOL (end-of-line) characters are translated to "\n"
-- * if last line in a file does not have an EOL character, this
-- streamer adds one, the ambiguity is due to "*l" stripping
-- * EOF uses an empty string to simplify testing in lexer
----------------------------------------------------------------------]]
--[[--------------------------------------------------------------------
-- local zio_init = require("lzio.lua")
-- local z = zio_init("@<filename>")
-- local z = zio_init("<string>")
-- z:getln()
-- * get next line from input stream
-- z.name
-- * name of the chunk, "@<filename>" or "=string"
----------------------------------------------------------------------]]
--[[--------------------------------------------------------------------
-- Format of z structure (ZIO)
-- z.getln -- chunk reader function, reads line-by-line
-- z.name -- name of stream
----------------------------------------------------------------------]]
return
function(buff)
--[[--------------------------------------------------------------------
-- initialize reader
-- * reader should return a string with an EOL character, or an empty
-- string if there is 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 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 data = h:read("*l")
if not data then h:close(); return "" end
return data.."\n"
end
else
----------------------------------------------------------------
-- create a chunk reader function from a source string
----------------------------------------------------------------
z.name = "=string"
reader = function()
if not buff then return nil end
local p, q, data, eol = string.find(buff, "([^\r\n]*)(\r?\n?)")
buff = string.sub(buff, q + 1)
if data == "" and eol == "" then return "" end
return data..eol
end
end
--[[--------------------------------------------------------------------
-- initialize input stream object
----------------------------------------------------------------------]]
if not reader then return end
z.getln = reader
return z
--[[------------------------------------------------------------------]]
end
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