mirror of
https://github.com/overleaf/overleaf.git
synced 2024-09-16 02:52:31 -04:00
48 lines
2.2 KiB
Markdown
48 lines
2.2 KiB
Markdown
This directory contains all the operational transform code. Each file defines a type.
|
|
|
|
Most of the types in here are for testing or demonstration. The only types which are sent to the webclient
|
|
are `text` and `json`.
|
|
|
|
|
|
# An OT type
|
|
|
|
All OT types have the following fields:
|
|
|
|
`name`: _(string)_ Name of the type. Should match the filename.
|
|
`create() -> snapshot`: Function which creates and returns a new document snapshot
|
|
|
|
`apply(snapshot, op) -> snapshot`: A function which creates a new document snapshot with the op applied
|
|
`transform(op1, op2, side) -> op1'`: OT transform function.
|
|
|
|
Given op1, op2, `apply(s, op2, transform(op1, op2, 'left')) == apply(s, op1, transform(op2, op1, 'right'))`.
|
|
|
|
Transform and apply must never modify their arguments.
|
|
|
|
|
|
Optional properties:
|
|
|
|
`tp2`: _(bool)_ True if the transform function supports TP2. This allows p2p architectures to work.
|
|
`compose(op1, op2) -> op`: Create and return a new op which has the same effect as op1 + op2.
|
|
`serialize(snapshot) -> JSON object`: Serialize a document to something we can JSON.stringify()
|
|
`deserialize(object) -> snapshot`: Deserialize a JSON object into the document's internal snapshot format
|
|
`prune(op1', op2, side) -> op1`: Inserse transform function. Only required for TP2 types.
|
|
`normalize(op) -> op`: Fix up an op to make it valid. Eg, remove skips of size zero.
|
|
`api`: _(object)_ Set of helper methods which will be mixed in to the client document object for manipulating documents. See below.
|
|
|
|
|
|
# Examples
|
|
|
|
`count` and `simple` are two trivial OT type definitions if you want to take a look. JSON defines
|
|
the ot-for-JSON type (see the wiki for documentation) and all the text types define different text
|
|
implementations. (I still have no idea which one I like the most, and they're fun to write!)
|
|
|
|
|
|
# API
|
|
|
|
Types can also define API functions. These methods are mixed into the client's Doc object when a document is created.
|
|
You can use them to help construct ops programatically (so users don't need to understand how ops are structured).
|
|
|
|
For example, the three text types defined here (text, text-composable and text-tp2) all provide the text API, supplying
|
|
`.insert()`, `.del()`, `.getLength` and `.getText` methods.
|
|
|
|
See text-api.coffee for an example.
|