1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
//! Snippet from cargo-hackerman crate, shows how to use derive to parse commands and
//! "positional_if" pattern.
//!
//! Command explain takes 3 parameters: required crate name and optional feature and crate version,
//! user is allowed to omitt either field. This example uses simplified is_version, in practice youwould
//! would use semver crate.
//!
//! End user would be able to run commands like
//!
//! ```console
//! $ cargo hackerman explain random 314
//! > krate: "random", feature: None, version: Some(314"),
//! $ cargo hackerman explain serde derive
//! > krate: "serde", feature: Some("derive"), version: None
//! ```
use bpaf::*;
#[derive(Debug, Clone, Bpaf)]
#[bpaf(options("hackerman"))]
pub enum Action {
#[bpaf(command("explain"))]
Explain {
#[bpaf(positional("CRATE"))]
krate: String,
#[bpaf(external(feature_if))]
feature: Option<String>,
#[bpaf(external(version_if))]
version: Option<String>,
},
}
fn feature_if() -> impl Parser<Option<String>> {
positional::<String>("FEATURE")
.guard(move |s| !is_version(s), "")
.optional()
}
fn version_if() -> impl Parser<Option<String>> {
positional::<String>("VERSION")
.guard(move |s| is_version(s), "")
.optional()
}
fn is_version(v: &str) -> bool {
v.chars().all(|c| c.is_numeric())
}
fn main() {
println!("{:?}", action().run());
}