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