✨ Add presence support #48
Open
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
alecgibson
force-pushed
the
presence-support
branch
from
458d825 to
5b3fb00
Compare
ericyhwang
reviewed
Dec 29, 2021
lib/json0.js
Outdated
|
|
||
| // Deletions should be treated as insertions: transforming | ||
| // by them should result in a no-op (null presence), so | ||
| // let's just pretend that deletions are oi to get the |
There was a problem hiding this comment.
The "pretend that deletions are oi" comment is confusing on first read, would be worth elaborating a bit more on how that works
There was a problem hiding this comment.
👍🏼 I've tried to clarify
README.md
Outdated
|
|
||
| The format of a `json0` presence object follows a similar syntax to its ops: | ||
|
|
||
| [{p: ['key', 123], v: 0}] |
There was a problem hiding this comment.
From the implementation, this shouldn't have an array wrapping it?
There was a problem hiding this comment.
Yup, docs were wrong. I've updated.
lib/json0.js
Outdated
| for (var i = 0; i < op.length; i++) { | ||
| var component = op[i]; | ||
| // Set side as 'right' because we always want the op to win ties, since | ||
| // our transformed "op" isn't really an op |
There was a problem hiding this comment.
Would be worth mentioning that for json0, this is just to handle subpath changes as a result of list move, insert, delete.
lib/json0.js
Outdated
| delete component.od; | ||
| } | ||
|
|
||
| if ('ld' in component) { |
There was a problem hiding this comment.
I'm curious if this breaks the json.transform(transformed, [component], 'right') lower down, if you, say, have presence on index 4 of an array and do a ld on index 2.
There was a problem hiding this comment.
Great catch. Fixed with a path check.
alecgibson
commented
Dec 29, 2021
alecgibson
force-pushed
the
presence-support
branch
3 times, most recently
from
7d721e7 to
fe0bd74
Compare
This change adds support for the `transformPresence()` method that
[`sharedb` uses][1].
We add support for both `text0` and `json0`.
`text0`
-------
The `text0` implementation leans on the existing
[`transformPosition`][2], and takes its form and tests from
[`rich-text`][3].
Its shape takes the form:
```js
{
index: 3,
length: 5,
}
```
Where:
- `index` is the cursor position
- `length` is the selection length (`0` for a collapsed selection)
`json0`
-------
The `json0` implementation has limited functionality because of the
limitations of the `json0` type itself: we handle list moves `lm`, but
cannot infer any information when moving objects around the tree,
because the `oi` and `od` operations are destructive.
However, it will attempt to transform embedded subtypes that support
presence.
Its shape takes the form:
```js
{
p: ['key', 123],
v: {},
}
```
Where:
- `p` is the path to the client's position within the document
- `v` is the presence value
The presence value `v` can take any arbitrary value (in simple cases it
may even be omitted entirely).
The exception to this is when using subtypes, where `v` should take the
presence shape defined by the subtype. For example, when using `text0`:
```js
{
p: ['key'],
v: {index: 5, length: 0},
}
```
[1]: share/sharedb#322
[2]: https://github.com/ottypes/json0/blob/90a3ae26364c4fa3b19b6df34dad46707a704421/lib/text0.js#L147
[3]: ottypes/rich-text#32
alecgibson
force-pushed
the
presence-support
branch
from
fe0bd74 to
58eea07
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fixes #30
This change adds support for the
transformPresence()method thatsharedbuses.We add support for both
text0andjson0.text0The
text0implementation leans on the existingtransformPosition, and takes its form and tests fromrich-text.Its shape takes the form:
Where:
indexis the cursor positionlengthis the selection length (0for a collapsed selection)json0The
json0implementation has limited functionality because of thelimitations of the
json0type itself: we handle list moveslm, butcannot infer any information when moving objects around the tree,
because the
oiandodoperations are destructive.However, it will attempt to transform embedded subtypes that support
presence.
Its shape takes the form:
Where:
pis the path to the client's position within the documentvis the presence valueThe presence value
vcan take any arbitrary value (in simple cases itmay even be omitted entirely).
The exception to this is when using subtypes, where
vshould take thepresence shape defined by the subtype. For example, when using
text0: