parity-common/fixed-hash

Fixed Hash

Provides macros to construct custom fixed-size hash types.

Examples

Simple 256 bit (32 bytes) hash type.

#[macro_use] extern crate fixed_hash;

construct_fixed_hash! {
    /// My 256 bit hash type.
    pub struct H256(32);
}

Opt-in to add conversions between differently sized hashes.

construct_fixed_hash!{ struct H256(32); }
construct_fixed_hash!{ struct H160(20); }
// auto-implement conversions between H256 and H160
impl_fixed_hash_conversions!(H256, H160);
// now use the generated conversions
assert_eq!(H256::from(H160::zero()), H256::zero());
assert_eq!(H160::from(H256::zero()), H160::zero());

It is possible to add attributes to your types, for example to make them serializable.

extern crate serde;
#[macro_use] extern crate serde_derive;

construct_fixed_hash!{
    /// My serializable hash type.
    #[cfg_attr(feature = "serialize", derive(Serialize, Deserialize))]
    struct H160(20);
}

Features

By default this is an standard library depending crate.
For a #[no_std] environment use it as follows:

fixed-hash = { version = "0.3", default-features = false }

Available Features

• std: Use the standard library instead of the core library.
  • Using this feature enables the following features
    • rustc-hex/std
    • rand/std
    • byteorder/std
  • Enabled by default.
• libc: Use libc for implementations of PartialEq and Ord.
  • Enabled by default.
• rand: Provide API based on the rand crate.
  • Enabled by default.
• byteorder: Provide API based on the byteorder crate.
  • Enabled by default.
• heapsize: Provide HeapsizeOf implementation for hash types.
  • Disabled by default.
• quickcheck: Provide quickcheck implementation for hash types.
  • Disabled by default.
• api-dummy: Generate a dummy hash type for API documentation.
  • Enabled by default at docs.rs