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local lpeg = require "lpeg"
local string = require "string"
local stringformat = string.format
local verboselvl = 0
local mk_out = function (stream, threshold, newlinep)
local out = io.stdout
if stream == "err" or stream == "stderr" then out = io.stderr end
return function (...)
if verboselvl >= threshold then
local ok, msg = pcall (stringformat, ...)
if ok then
out:write (msg)
if newlinep == true then out:write "\n" end
---else silently ignore
end
end
end
end
local set_verbosity = function (n) verboselvl = n end
local trim_whitespace
local unescape_string
local internalize_value
do
local P = lpeg.P
local S = lpeg.S
local Cs = lpeg.Cs
local p_ws_char = S" \n\r\t\v"
local p_ws = p_ws_char^1
local p_ws_trailing = p_ws * P (-1)
local p_ws_drop = Cs ( (p_ws^-1 / "")
* (1 - p_ws_trailing)^0
* (p_ws^-1 * P (-1) / ""))
local p_escape_char = (P"\\n" / "\n")
+ (P"\\r" / "\r")
+ (P"\\t" / "\t")
+ (P"\\v" / "\v")
local p_unescape = Cs ((p_escape_char + 1)^0)
--[[--
rfc2445, sec. 4.1.2: Properties can have multiple values, separated by a
literal comma, thus text commas are escaped.
--]]--
local p_value_char = ( p_escape_char
+ P"\\," / ","
+ P"," / "\n")
local p_value = Cs ((p_value_char + 1)^0)
local lpegmatch = lpeg.match
trim_whitespace = function (s) return lpegmatch (p_ws_drop , s) end
unescape_string = function (s) return lpegmatch (p_unescape, s) end
internalize_value = function (s) return lpegmatch (p_value, s) end
end
return
{ println = mk_out ("stdout", 0, true)
, errorln = mk_out ("stderr", 0, true)
, noiseln = mk_out ("stderr", 1, true)
, debugln = mk_out ("stderr", 2, true)
, set_verbosity = set_verbosity
, trim_whitespace = trim_whitespace
, unescape_string = unescape_string
, internalize_value = internalize_value
}
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