util.dbuffer: dynamic string buffer
Similar to util.ringbuffer (and shares almost identical API). Differences:
- size limit is optional and dynamic
- does not allocate a fixed buffer of max_size bytes
- focus on simply storing references to existing string objects where possible,
avoiding unnecessary allocations
- references are still stored in a ring buffer to enable use as a fast FIFO
Optional second parameter to new() provides the number of ring buffer segments. On
Lua 5.2 on my laptop, a segment is ~19 bytes. If the ring buffer fills up, the next
write will compact all strings into a single item.
-- Prosody IM
-- Copyright (C) 2008-2011 Florian Zeitz
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--
-- luacheck: ignore 113/setfenv 113/loadstring
local load, loadstring, setfenv = load, loadstring, setfenv;
local io_open = io.open;
local envload;
local envloadfile;
if setfenv then
function envload(code, source, env)
local f, err = loadstring(code, source);
if f and env then setfenv(f, env); end
return f, err;
end
function envloadfile(file, env)
local fh, err, errno = io_open(file);
if not fh then return fh, err, errno; end
local f, err = load(function () return fh:read(2048); end, "@"..file);
fh:close();
if f and env then setfenv(f, env); end
return f, err;
end
else
function envload(code, source, env)
return load(code, source, nil, env);
end
function envloadfile(file, env)
local fh, err, errno = io_open(file);
if not fh then return fh, err, errno; end
local f, err = load(fh:lines(2048), "@"..file, nil, env);
fh:close();
return f, err;
end
end
return { envload = envload, envloadfile = envloadfile };