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.
Pnicking on oversized slice is useful to catch errors in code that's
supposed to know the exact sizes but this is undesirable in code that
doesn't. These two methods help with handling the case when `buf.len()`
is not known upfront.
1bf885550e Redesign `hex::BufEncoder` to accept owned arrays (Martin Habovstiak)
Pull request description:
Not being able to create an owned `BufEncoder` prevented returning it from functions which need to allocate the buffer on stack. Such is the case in WIP serde via consensus serialzation.
This change refactors `OutBytes` to be unsized, adds an `AsOutBytes` trait and uses that one instead of `Into` to perform the conversion.
Closes#1270
This is meant as potentially mergeable demonstration. Interestingly, it was easier than I expected.
ACKs for top commit:
tcharding:
Except for the question about the `out_bytes` module, ACK 1bf885550e
apoelstra:
ACK 1bf885550e
Tree-SHA512: 39bc48e54ae0e66b988ba5ad6ea7ecbe03e5f4c71792df0f8e2b03aa2e97e2c0fac1cb03e84ecac12ec6f13649554b57e1000710c34c638d17d9bb575d0ac0a1
Not being able to create an owned `BufEncoder` prevented returning it
from functions which need to allocate the buffer on stack. Such is the
case in WIP serde via consensus serialzation.
This change refactors `OutBytes` to be unsized, adds an `AsOutBytes`
trait and uses that one instead of `Into` to perform the conversion.
There's a `hex` module in `bitcoin_hashes` which is a bit out of place
and not very fast - it passes each *digit* through dynamic dispatch not
only adding overhead but also not allowing `String` to make better
allocations.
This change adds basic support for hex encoding using a stack-allocated
buffer which minimizes the overhead of dynamic dispatch. It also
provides a new `DisplayHex` trait designed to replace `ToHex` found in
`bitcoin_hashes`.
Tobin C. Harding
Martin Habovstiak
Andrew Poelstra