local gsub = string.gsub
local chars
local function get_chars()
chars, get_chars = {
["\000"] = "%z", ["$"] = "%$", ["%"] = "%%", ["("] = "%(", [")"] = "%)",
["*"] = "%*", ["+"] = "%+", ["-"] = "%-", ["."] = "%.", ["?"] = "%?",
["["] = "%[", ["]"] = "%]", ["^"] = "%^",
}, nil
return chars
end
--[==[Escapes the magic characters used in a pattern: {$%()*+-.?[]^}, and converts the null character to {%z}. For example, {"^$()%.[]*+-?\0"} becomes {"%^%$%(%)%%%.%[%]%*%+%-%?%z"}. This is necessary when constructing a pattern involving arbitrary text (e.g. from user input).]==]
return function(str)
return (gsub(str, "[%z$%%()*+%-.?[%]^]", chars or get_chars()))
end
