A simple library to parse commandline arguments in Lua.
local arrr = require 'arrr'
local parser = arrr {
{"Foos two bars", "--foo", "-f", {'first', 'second'}};
}
local options = parser {...}
print(options.foo.first, options.foo.second)
The library is intentionally simple and doesn't provide any advanced features. Its main goal is to be portable, usable as a rock or just a copy-in Lua file, easy to understand and maintain and easy to hack.
Structure of an argument description:
- Description
- Long name
- Short name (can be nil for none)
- Argument count or names
- Nil for a boolean flag
- True for single argument
- Number to collect that many arguments in a sequence
- Array of keys to collect arguments into a table
- An Asterisk * for a variable length of arguments that don't start with -
- A delimiter string to read arguments until it matches
Additionally, the following options can be passed in the argument descriptor as string keys:
- `filter` A function to filter the argument through
- `repeatable` Makes it so the flag can be given multiple times and collects
its values into a sequence
Long argument names work as expected. Short ones can be combined into one, and if they take arguments, they will be read in order:
lua my_script -f foo -b bar
lua my_script -fb foo bar # identical to above
Unknown arguments and extra positional arguments will simply be returned at integer positions.
Setting the unknown field on a parser to a callback will make it call its
value for every unknown parameter that it encounters and drop the parameter,
should the callback return a truthy value.
local parser = arrr { --[[ parses nothing ]] }
function parser.unknown(token, data)
table.insert(data, token:gsub("^--?", "")) -- Remove leading dash(es)
return true -- Drop the parameter, because it was already handled
end
parser { "--unknown" } -- returns { "unknown" }
At any position where a new argument is expected, a -- will immediately stop
parsing arguments and return all following arguments unmodified as positional
arguments.