bear/lib/cli.vr

// cli.vr — getopt-style command-line flag parsing for command-line tools.
//
//   import cli
//   fn main() {
//       let name = cli.flag("name", "world")   // --name bob | --name=bob | -n bob
//       let verbose = cli.has("v")             // -v  (boolean flag)
//       let rest = cli.positional()            // non-flag args
//       println("hi " + name)
//   }
//
// Parsing is done by the VM (full string handling); this module exposes it as
// namespaced helpers. Supported forms:
//
//   --name value    long flag with a space-separated value
//   --name=value    long flag with an inline value
//   --name          long boolean flag
//   -v              short flag, treated as boolean (never swallows a positional)
//   -n=value        short flag with an inline value
//
// The short alias is the long name's first character (`--verbose` -> `-v`). To
// give a value to a short flag, use the inline form `-n=value` (or the long
// form `--name value`). `--` stops flag parsing; everything after is
// positional. The first occurrence of a flag wins. Negative numbers (-5) are
// values, not flags.

// flag returns the value of the named flag, or `default` when absent.
fn flag(name, default) {
	let v = flag_val(name)
	if v == "" {
		return default
	}
	return v
}

// has returns 1 when the flag was passed (boolean or with a value), else 0.
fn has(name) {
	return flag_has(name)
}

// positional returns the non-flag arguments in order; `--` ends flag parsing.
fn positional() {
	return flag_positional()
}