The Rust API has so far grown somewhat organically driven by the needs of the
javascript implementation. This has led to an API which is quite awkward and
unfamiliar to Rust programmers. Additionally there is no documentation to speak
of. This commit is the first movement towards cleaning things up a bit. We touch
a lot of files but the changes are all very mechanical. We introduce a few
traits to abstract over the common operations between `Automerge` and
`AutoCommit`, and add a whole bunch of documentation.
* Add a `ReadDoc` trait to describe methods which read value from a document.
make `Transactable` extend `ReadDoc`
* Add a `SyncDoc` trait to describe methods necessary for synchronizing
documents.
* Put the `SyncDoc` implementation for `AutoCommit` behind `AutoCommit::sync` to
ensure that any open transactions are closed before taking part in the sync
protocol
* Split `OpObserver` into two traits: `OpObserver` + `BranchableObserver`.
`BranchableObserver` captures the methods which are only needed for observing
transactions.
* Add a whole bunch of documentation.
The main changes Rust users will need to make is:
* Import the `ReadDoc` trait wherever you are using the methods which have been
moved to it. Optionally change concrete paramters on functions to `ReadDoc`
constraints.
* Likewise import the `SyncDoc` trait wherever you are doing synchronisation
work
* If you are using the `AutoCommit::*_sync_message` methods you will need to add
a call to `AutoCommit::sync()` first. E.g. `doc.generate_sync_message` becomes
`doc.sync().generate_sync_message`
* If you have an implementation of `OpObserver` which you are using in an
`AutoCommit` then split it into an implementation of `OpObserver` and
`BranchableObserver`
The wasm codebase assumed that clients want to represent text as a
string of characters. This is faster, but in order to enable backwards
compatibility we add a `TextRepresentation` argument to
`automerge_wasm::Automerge::new` to allow clients to choose between a
`string` or `Array<any>` representation. The `automerge_wasm::Observer`
will consult this setting to determine what kind of diffs to generate.
Automerge CLI depends transitively (via and old version of `clap` and
via `colored_json` on `atty` and `ansi_term`. These crates are both
marked as unmaintained and this generates irritating `cargo deny`
messages. To avoid this, implement colored JSON ourselves using the
`termcolor` crate - colored JSON is pretty mechanical. Also update
criterion and cbindgen dependencies and ignore the criterion tree in
deny.toml as we only ever use it in benchmarks.
All that's left now is a warning about atty in cbindgen, we'll just have
to wait for cbindgen to fix that, it's a build time dependency anyway so
it's not really an issue.
* Use AMbyteSpan for byte values
Before this change there was an inconsistency between AMmapPutString
(which took an AMbyteSpan) and AMmapPutBytes (which took a pointer +
length).
Either is fine, but we should do the same in both places. I chose this
path to make it clear that the value passed in was an automerge value,
and to be symmetric with AMvalue.bytes when you do an AMmapGet().
I did not update other APIs (like load) that take a pointer + length, as
that is idiomatic usage for C, and these functions are not operating on
byte values stored in automerge.
* More detailed instructions in README
I struggled to get the project to build for a while when first getting
started, so have added some instructions; and also some usage
instructions for automerge-c that show more clearly what is happening
without `AMpush()`
Transactions with no ops in them are generally undesirable. They take up
space in the change log but do nothing else. They are not useless
though, it may occasionally be necessary to create an empty change in
order to list all the current heads of the document as dependents of the
empty change.
The current API makes no distinction between empty changes and non-empty
changes. If the user calls `Transaction::commit` a change is created
regardless of whether there are ops to commit. To provide a more useful
API modify `commit` so that if there is a no-op transaction then no
changes are created, but provide explicit methods to create an empty
change via `Transaction::empty_change`, `Automerge::empty_change` and
`Autocommit::empty_change`. Also make these APIs available in Javascript
and C.
After some discussion with PVH I realise that the repo structure in the
last reorg was very rust-centric. In an attempt to put each language on
a level footing move the rust code and project files into ./rust
