HackMD/lib/ot/server.js

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var config = require('../config');
if (typeof ot === 'undefined') {
var ot = {};
}
ot.Server = (function (global) {
'use strict';
// Constructor. Takes the current document as a string and optionally the array
// of all operations.
function Server (document, operations) {
this.document = document;
this.operations = operations || [];
}
// Call this method whenever you receive an operation from a client.
Server.prototype.receiveOperation = function (revision, operation) {
if (revision < 0 || this.operations.length < revision) {
throw new Error("operation revision not in history");
}
// Find all operations that the client didn't know of when it sent the
// operation ...
var concurrentOperations = this.operations.slice(revision);
// ... and transform the operation against all these operations ...
var transform = operation.constructor.transform;
for (var i = 0; i < concurrentOperations.length; i++) {
operation = transform(operation, concurrentOperations[i])[0];
}
// ... and apply that on the document.
var newDocument = operation.apply(this.document);
// ignore if exceed the max length of document
if(newDocument.length > config.documentMaxLength && newDocument.length > this.document.length)
return;
this.document = newDocument;
// Store operation in history.
this.operations.push(operation);
// It's the caller's responsibility to send the operation to all connected
// clients and an acknowledgement to the creator.
return operation;
};
return Server;
}(this));
if (typeof module === 'object') {
module.exports = ot.Server;
}