clap-digest

Integration to choose digest with clap on a CLI.

Features

1. A clap::ValueEnum implementation for the different digest algorithm types:

   let algorithm = Arg::with_name("algorithm")
       .short('a')
       .long("algorithm")
       .help("digest algorithm")
       .takes_value(true)
       // this here is the important bit:
       .value_parser(clap::builder::EnumValueParser::<Digest>::new());
   

2. A conversion from clap_digest::Digest to digest::DynDigest:

   // fn doing some hashing, using any DynDigest implementation
   fn dyn_hash(hasher: &mut dyn DynDigest, data: &[u8]) -> String {
       hasher.update(data);
       let hash = hasher.finalize_reset();
       hash.iter().map(|byte| format!("{:02x}", byte)).collect()
   }
   
   // parse user-supplied CLI input to clap_digest::Digest with clap
   // suppose user runs this with: `command --algorithm MD5`
   // let args = cli.get_matches();
   let digest = *args.get_one::<Digest>("algorithm").unwrap();
   
   // convert to DynDigest
   let mut digest: Box<dyn DynDigest> = digest.into();
   
   // use with hashing function
   let hash = dyn_hash(&mut (*digest), b"foo");
   
   assert_eq!(hash, "acbd18db4cc2f85cedef654fccc4a4d8");
   

3. Algorithm groups are feature-gated (see example below). Use cargo feature clap-digest for a complete listing.

Example

For a complete CLI example, see examples/cksum.rs.

$ cargo run --example cksum -- -a SHA1 Cargo.toml
7a96ee85606435fe1f39c3fa6bdf4cf9bbbc338c  Cargo.toml

$ sha1sum Cargo.toml
7a96ee85606435fe1f39c3fa6bdf4cf9bbbc338c  Cargo.toml

$ cargo run --example cksum -- -a MD5 Cargo.toml | md5sum -c
Cargo.toml: OK

List all supported algorithms:

$ cargo run --example cksum -- --list-algorithms
BLAKE2b512
BLAKE2s256
BLAKE3
...

All algorithm groups are feature-gated, so you can choose:

$ cargo run --example cksum --no-default-features --features md5,sha1,sha2 -- --list-algorithms
MD5
SHA1
SHA224
SHA256
SHA384
SHA512
SHA512/224
SHA512/256