Crate shift

Parsing command line arguments

Call parse to get a Bag from which options, flags and operands may be extracted.

Supported syntax

GNU-style command line invocations like the following are supported:

exe commit --verbose --level=info --message message
exe -v -l=info -m message

Anything prefixed with a - or -- is treated as an option or flag. The following command lines are equivalent:

exe -one -two -3
exe --one --two --3

After parsing this, you’ll be able to extract three flags: one, two and 3.

The end of options marker -- is respected. Any arguments that come after it are treated as operands (i.e. positional arguments)

While the order the command line arguments appear in is irrelevant, the order in which you extract them is. In particular, when a switch is followed by a value, it is ambiguous whether it should be treated as an option or a flag. The order in which methods are called resolves this ambiguity:

// Treated as a flag followed by a positional argument
let mut bag = shift::parse(vec![
    String::from("program"),
    String::from("--option"),
    String::from("value")
]).unwrap();
assert_eq!(bag.shift_flag("option"), true);
assert_eq!(bag.shift_operand().as_deref(), Some("value"));
assert!(bag.is_empty());

// Treated as an option
let mut bag = shift::parse(vec![
    String::from("program"),
    String::from("--option"),
    String::from("value")
]).unwrap();
assert_eq!(bag.shift_option("option").as_deref(), Some("value"));
assert!(bag.is_empty());

Structs

Bag

Parsed command line arguments

Enums

ParseError

A command line parsing error

Functions

parse

Parses the given command line arguments into a bag