Currently we have a few things mixed up in the feature gating of
`hashes`.
Observe that:
- `io::Write` is not related to allocation.
- "std" should be able to enable "alloc".
Improve feature gating by doing:
- Enable "alloc" from "std" and simplify `cfg` codebase wide.
- Enable "internals/alloc" from "alloc".
- Fix feature gating to use the minimal requirement i.e., "alloc".
Remove `FromHex` from hash and script types
- Remove the `FromHex` implementation from hash types and `ScriptBuf`
- Remove the `FromStr` implementation from `ScriptBuf` because it does not
roundtrip with `Display`.
- Implement a method `from_hex` on `ScriptBuf`.
- Implement `FromStr` on hash types using a fixed size array.
This leaves `FromHex` implementations only on `Vec` and fixed size arrays.
The `ToHex` trait was replaced by either simple `Display`/`LowerHex`
where appropriate or `DisplayHex` from `bitcoin_internals` which is
faster.
This change replaces the usages and removes the trait.
`bitcoin-internals` contains a more performant implementation of hex
encoding than what `bitcoin_hashes` uses internally. This switches the
implementations for formatting trait implementations as a step towards
moving over completely.
The public macros are also changed to delegate to inner type which is
technically a breaking change but we will break the API anyway and the
consuers should only call the macro on the actual hash newtypes where
the inner types already have the appropriate implementations.
Apart from removing reliance on internal hex from public API this
reduces duplicated code generated and compiled. E.g. if you created 10
hash newtypes of SHA256 the formatting implementation would be
instantiated 11 times despite being the same.
To do all this some other changes were required to the hex
infrastructure. Mainly modifying `put_bytes` to accept iterator (so that
`iter().rev()` can be used) and adding a new `DisplayArray` type. The
iterator idea was invented by Tobin C. Harding, this commit just adds a
bound check and generalizes over `u8` and `&u8` returning iterators.
While it may seem that `DisplayByteSlice` would suffice it'd create and
initialize a large array even for small arrays wasting performance.
Knowing the exact length `DisplayArray` fixes this.
Another part of refactoring is changing from returning `impl Display` to
return `impl LowerHex + UpperHex`. This makes selecting casing less
annoying since the consumer no longer needs to import `Case` without
cluttering the API with convenience methods.
We would like to bring the `bitcoin_hashes` crate into the
`rust-bitcoin` repository.
Import `bitcoin_hashes` into `rust-bitocin/hashes`, doing so looses all
the commit history from the original crate but if we archive the
original repository then the history will be preserved. We maintain the
same version number obviously and in the changelog we note the change of
repository.
Commit hash that was tip of `bitcoin_hashes` at time of import:
commit 54c16249e06cc6b7870c7fc07d90f489d82647c7
Includes making `embedded` and `fuzzing` per-crate i.e., move them into
`bitcoin` as hashes includes these also.
NOTE: Does _not_ enable fuzzing for `hashes` in CI.
Notes on CI:
Attempts to merge in the github actions from the hashes crate however reduces
coverage by not running hashes tests for beta toolchain. Some additional
work could be done to improve the CI to increase efficiency without
reducing coverage. Leaving for another day.
Tobin C. Harding
Martin Habovstiak
sanket1729