rust-node: binary Node ID and conversion utilities...
rust-node: binary Node ID and conversion utilities
The choice of type makes sure that a `Node` has the exact
wanted size. We'll use a different type for prefixes.
Added dependency: hexadecimal conversion relies on the
`hex` crate.
The fact that sooner or later Mercurial is going to need
to change its hash sizes has been taken strongly in
consideration:
- the hash length is a constant, but that is not directly
exposed to callers. Changing the value of that constant
is the only thing to do to change the hash length (even
in unit tests)
- the code could be adapted to support several sizes of hashes,
if that turned out to be useful. To that effect, only the
size of a given `Node` is exposed in the public API.
- callers not involved in initial computation, I/O and FFI
are able to operate without a priori assumptions on the hash
size. The traits `FromHex` and `ToHex` have not been directly
implemented, so that the doc-comments explaining these
restrictions would stay really visible in `cargo doc`
Differential Revision:
https://phab.mercurial-scm.org/D7788
