Pirate [](https://travis-ci.org/zcdziura/pirate)
======
A command-line arrrrguments parser, written in Rust.
Synopsis
--------
Most programs that provide a command-line interface use a special-purpose library to make the process easier, such as the GNU Project's `getopt` library. The Rust team provides their own alternative, `getoptions`, which deserves an award for the Most Originally Named Project Ever.
In all seriousness, `getoptions` is a fantastic library that gives the developers all of the power necessary to create and interface with command-line arguments. However, with all that power comes complexity. `getoptions` -- while straight forward to use -- is verbose. The developer has to call different functions repeatedly in order to add different command-line options to their programs. While the only victim here is the developer's wrists due to carpal tunnel, I felt that there was a
better way to do things.
Enter Pirate (which should totally usurp `getoptions` for the award of Most Originally Named Project Ever).
Installation
------------
Add this to your project's `Cargo.toml` file:
```
[dependencies]
pirate = "1.0.0"
```
and this to your crate root:
```rust
extern crate pirate;
```
Usage
-----
Using Pirate is simple. First, create a vector defining all of the valid options that your program accepts:
```rust
let options = vec![
"a/addend#The right side of the addition equation; default=1:",
"#Required Arguments",
":augend#The left side of an addition equation"
];
```
Options are defined in a very specific format:
* Options that have an associated argument must be followed by a colon (:). The colon must be the last character of the option (see above for example).
* Long-form options are denoted by a preceding slash (/). Options are able to have short- and long-forms. Options which are only long-form still need a preceding slash, e.g. `"/addend"`.
* Required program arguments must have a preceding colon as the first character of the opt, e.g. `":augend"`.
* Option descriptions are denoted by a proceding hash (#). Descriptions are optional and are used to display helpful information about the option when displaying a program's usage information (typically when the `--help` flag is passed). Options with **only** a description (i.e. no short- or long-form name) are called "Groups", and are used to group options together when displaying usage.
Next, create a `Vars` struct, which is responsible for keeping track of all of the options, along with the program's name, defined for the program:
```rust
let vars: Vars = match pirate::vars("program-name", &options) {
Ok(v) => v,
Err(why) => panic!("Error: {}", why)
}
```
Next, call the `pirate::matches()` function, passing in a vector of the program's environment arguments, along with a mutable reference to the `Vars` struct that you previously defined:
```rust
let matches: Matches = match pirate::matches(env::args().collect(),
&mut vars) {
Ok(m) => m,
Err(why) => {
println!("Error: {}", why);
pirate::usage(&vars);
return;
}
}
```
`Matches` is nothing more than a type alias to a `HashMap<String, String>`. All of the custom methods that make the type easier to use are defined by the `Match` trait.
And finally, check which arguments were passed to the program.
```
// Returns a reference to the given arg, or None if not found
fn get(arg: &str) -> Option<&String>;
// Returns true if the match exists, false if not
fn has_match(arg: &str) -> bool;
// An iterator over all matches found
fn keys() -> Keys<String, String>;
```
Something to remember when using the `get()` function: by default, the `pirate::matches()` function stores the opt's long-form name as the key, by default, should the long-form exist; otherwise the short-form is used. So, should you define an opt with both a short- and long-form name, when querying for it, pass the long-form as the argument. For example:
```rust
let options = vec!["l/long#An example opt"];
let vars = pirate::vars("program-name", &options);
let matches = pirate::matches(&env::args().collect(),
&mut vars).unwrap();
let short = matches.get("l").unwrap(); // Error! This won't work!
let long = matches.get("long").unwrap(); // Success!
// Usage: program-name -l
```
As shown in a previous example, should you ever want to display the program's usage data, simply call the `pirate::usage()` function, passing in a reverence to your `Vars` struct as an argument. E.g. `pirate::usage(&vars)`
Example
-------
Here is a trivial example that gives a general idea about how to use `pirate`:
```rust
extern crate pirate;
use pirate::{Matches, Match, matches, usage, vars};
fn main() {
let env_args: Vec<String> = vec![
String::from("test"),
String::from("-a"), String::from("2"),
String::from("3")
];
let options = vec![
"a/addend#The right side of the addition equation; default=1:",
"#Required Arguments",
":augend#The left side of an addition equation"
];
let mut vars = vars("test", &options).unwrap();
let matches: Matches = match matches(&env_args, &mut vars) {
Ok(m) => m,
Err(why) => {
println!("Error: {}", why);
usage(&vars);
return;
}
};
if matches.has_match("help") {
usage(&vars);
return;
}
let augend: i32 = matches.get("augend")
.unwrap()
.parse::<i32>()
.unwrap();
let addend: i32 = match matches.get("addend") {
Some(a) => a.parse::<i32>().unwrap(),
None => 1
};
let sum = augend + addend;
println!("{} + {} = {}", augend, addend, sum);
}
```
License
-------
Pirate is licensed under the [GNU Lesser General Public License, v3](https://www.gnu.org/licenses/lgpl.html).