Instead of always requiring the full raw script and leaf version, allow
just specifying a raw leaf hash to the sighash computation functions.
This is very useful when dealing with PSBTs, because the
`PSBT_IN_TAP_BIP32_DERIVATION` field only maps a public key to a leaf
hash, so a signer could just take it and produce a signature with it
rathern than having to jump through hoops to recover the full raw
script.
This is the initial step towards using and maybe enforcing clippy.
It does not fix all lints as some are not applicable. They may be
explicitly ignored later.
Docs can always do with a bit of love.
Clean up the module level (`//!`) rustdocs for all public modules.
I claim uniform is better than any specific method/style. I tried to fit
in with what ever was either most sane of most prevalent, therefore
attaining uniformity without unnecessary code churn (one exception being
the changes to headings described below).
Notes:
* Headings - use heading as a regular sentence for all modules e.g.,
```
//! Bitcoin network messages.
```
as opposed to
```
//! # Bitcoin Network Messages
```
It was not clear which style to use so I picked a 'random' mature
project and copied their style.
* Added 'This module' in _most_ places as the start of the module
description, however I was not religious about this one.
* Fixed line length if necessary since most of our code seems to follow
short (80 char) line lengths for comments anyways.
* Added periods and fixed obvious (and sometimes not so obvious)
grammatically errors.
* Added a trailing `//!` to every block since this was almost universal
already. I don't really like this one but I'm guessing it is Andrew's
preferred style since its on the copyright notices as well.
This refactors the code to make it possible to use `get_or_insert_with`
instead of unwrapping in `segwit_cache()`. To achieve it `common_cache`
is refactored into two functions: one taking only the required borrows
and the original calling the new one. `segwit_cache` then calls the new
function so that borrows are OK.
Apart from removing unwrap, this avoids calling `common_cache` multiple
times.
There was a question whether this is equally performant. There are
multiple good reasons why it should be:
1. `get_or_insert_with` is marked `#[inline]`
2. Any good optimizer will inline a function that is used exactly once
3. 1 and 2 conclude that the closure will get inlined
4. Computing self.tx can then be moved to the only branch where it is
required.
5. Even if get_or_insert_with didn't get optimized, which is extremely
unlikely, the `tx` field is at the beginning of the struct and it
probably has pointer alignment (`Deref` suggests it's a pointer).
Alignment larger than pointer is not used, so we can expect the
fields to be ordered as-defined. (This is not guaranteed by Rust but
there's not good reason to change the order in this case.) We can
assume that offset to tx is zero in most cases which means no
computation is actually needed so the expression before closure is
no-op short of passing it into the closure as an argument.
At the time of writing `#[inline]` can be seen at
https://doc.rust-lang.org/src/core/option.rs.html#933