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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:
-- * EOZ is implemented as a string, "EOZ"
-- * Format of z structure (ZIO)
-- z.n -- bytes still unread
-- z.p -- last read position in buffer
-- z.reader -- chunk reader function
-- z.data -- additional data
-- z.name -- name of stream
-- * Current position, p, is now last read index instead of a pointer
--
-- Not implemented:
-- * luaZ_lookahead: used only in lapi.c:lua_load to detect binary chunk
-- * luaZ_read: used only in lundump.c:ezread to read +1 bytes
-- * luaZ_openspace: dropped; let Lua handle buffers as strings
-- * luaZ buffer macros: dropped; unused for now
--
-- Alternatives:
-- * zname(z) is z.name
--
-- Added:
-- (both of the following are vaguely adapted from lauxlib.c)
-- * luaZ:make_getS: create Chunkreader from a string
-- * luaZ:make_getF: create Chunkreader that reads from a file
----------------------------------------------------------------------]]
luaZ = {}
------------------------------------------------------------------------
-- * reader() should return a string, or nil if nothing else to parse.
-- Unlike Chunkreaders, there are no arguments like additional data
-- * Chunkreaders are handled in lauxlib.h, see luaL_load(file|buffer)
-- * Original Chunkreader:
-- const char * (*lua_Chunkreader) (lua_State *L, void *ud, size_t *sz);
-- * This Lua chunk reader implementation:
-- returns string or nil, no arguments to function
------------------------------------------------------------------------
------------------------------------------------------------------------
-- create a chunk reader from a source string
------------------------------------------------------------------------
function luaZ:make_getS(buff)
local b = buff
return function() -- chunk reader anonymous function here
if not b then return nil end
local data = b
b = nil
return data
end
end
------------------------------------------------------------------------
-- create a chunk reader from a source file
------------------------------------------------------------------------
function luaZ:make_getF(filename)
local LUAL_BUFFERSIZE = 512
local h = io.open(filename, "r")
if not h then return nil end
return function() -- chunk reader anonymous function here
if not h or io.type(h) == "closed file" then return nil end
local buff = h:read(LUAL_BUFFERSIZE)
if not buff then h:close(); h = nil end
return buff
end
end
------------------------------------------------------------------------
-- creates a zio input stream
-- returns the ZIO structure, z
------------------------------------------------------------------------
function luaZ:init(reader, data, name)
if not reader then return end
local z = {}
z.reader = reader
z.data = data or ""
z.name = name
-- set up additional data for reading
if not data or data == "" then z.n = 0 else z.n = string.len(data) end
z.p = 0
return z
end
------------------------------------------------------------------------
-- fill up input buffer
------------------------------------------------------------------------
function luaZ:fill(z)
local data = z.reader()
z.data = data
if not data or data == "" then return "EOZ" end
z.n = string.len(data) - 1
z.p = 1
return string.sub(data, 1, 1)
end
------------------------------------------------------------------------
-- get next character from the input stream
------------------------------------------------------------------------
function luaZ:zgetc(z)
if z.n > 0 then
z.n = z.n - 1
z.p = z.p + 1
return string.sub(z.data, z.p, z.p)
else
return self:fill(z)
end
end
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