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rOACCT/node_modules/websocket-extensions/lib/websocket_extensions.js
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websocket_extensions.js
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			'use strict';

			var Parser = require('./parser'),
			Pipeline = require('./pipeline');

			var Extensions = function() {
			this._rsv1 = this._rsv2 = this._rsv3 = null;

			this._byName = {};
			this._inOrder = [];
			this._sessions = [];
			this._index = {};
			};

			Extensions.MESSAGE_OPCODES = [1, 2];

			var instance = {
			add: function(ext) {
			if (typeof ext.name !== 'string') throw new TypeError('extension.name must be a string');
			if (ext.type !== 'permessage') throw new TypeError('extension.type must be "permessage"');

			if (typeof ext.rsv1 !== 'boolean') throw new TypeError('extension.rsv1 must be true or false');
			if (typeof ext.rsv2 !== 'boolean') throw new TypeError('extension.rsv2 must be true or false');
			if (typeof ext.rsv3 !== 'boolean') throw new TypeError('extension.rsv3 must be true or false');

			if (this._byName.hasOwnProperty(ext.name))
			throw new TypeError('An extension with name "' + ext.name + '" is already registered');

			this._byName[ext.name] = ext;
			this._inOrder.push(ext);
			},

			generateOffer: function() {
			var sessions = [],
			offer = [],
			index = {};

			this._inOrder.forEach(function(ext) {
			var session = ext.createClientSession();
			if (!session) return;

			var record = [ext, session];
			sessions.push(record);
			index[ext.name] = record;

			var offers = session.generateOffer();
			offers = offers ? [].concat(offers) : [];

			offers.forEach(function(off) {
			offer.push(Parser.serializeParams(ext.name, off));
			}, this);
			}, this);

			this._sessions = sessions;
			this._index = index;

			return offer.length > 0 ? offer.join(', ') : null;
			},

			activate: function(header) {
			var responses = Parser.parseHeader(header),
			sessions = [];

			responses.eachOffer(function(name, params) {
			var record = this._index[name];

			if (!record)
			throw new Error('Server sent an extension response for unknown extension "' + name + '"');

			var ext = record[0],
			session = record[1],
			reserved = this._reserved(ext);

			if (reserved)
			throw new Error('Server sent two extension responses that use the RSV' +
			reserved[0] + ' bit: "' +
			reserved[1] + '" and "' + ext.name + '"');

			if (session.activate(params) !== true)
			throw new Error('Server sent unacceptable extension parameters: ' +
			Parser.serializeParams(name, params));

			this._reserve(ext);
			sessions.push(record);
			}, this);

			this._sessions = sessions;
			this._pipeline = new Pipeline(sessions);
			},

			generateResponse: function(header) {
			var sessions = [],
			response = [],
			offers = Parser.parseHeader(header);

			this._inOrder.forEach(function(ext) {
			var offer = offers.byName(ext.name);
			if (offer.length === 0 \|\| this._reserved(ext)) return;

			var session = ext.createServerSession(offer);
			if (!session) return;

			this._reserve(ext);
			sessions.push([ext, session]);
			response.push(Parser.serializeParams(ext.name, session.generateResponse()));
			}, this);

			this._sessions = sessions;
			this._pipeline = new Pipeline(sessions);

			return response.length > 0 ? response.join(', ') : null;
			},

			validFrameRsv: function(frame) {
			var allowed = { rsv1: false, rsv2: false, rsv3: false },
			ext;

			if (Extensions.MESSAGE_OPCODES.indexOf(frame.opcode) >= 0) {
			for (var i = 0, n = this._sessions.length; i < n; i++) {
			ext = this._sessions[i][0];
			allowed.rsv1 = allowed.rsv1 \|\| ext.rsv1;
			allowed.rsv2 = allowed.rsv2 \|\| ext.rsv2;
			allowed.rsv3 = allowed.rsv3 \|\| ext.rsv3;
			}
			}

			return (allowed.rsv1 \|\| !frame.rsv1) &&
			(allowed.rsv2 \|\| !frame.rsv2) &&
			(allowed.rsv3 \|\| !frame.rsv3);
			},

			processIncomingMessage: function(message, callback, context) {
			this._pipeline.processIncomingMessage(message, callback, context);
			},

			processOutgoingMessage: function(message, callback, context) {
			this._pipeline.processOutgoingMessage(message, callback, context);
			},

			close: function(callback, context) {
			if (!this._pipeline) return callback.call(context);
			this._pipeline.close(callback, context);
			},

			_reserve: function(ext) {
			this._rsv1 = this._rsv1 \|\| (ext.rsv1 && ext.name);
			this._rsv2 = this._rsv2 \|\| (ext.rsv2 && ext.name);
			this._rsv3 = this._rsv3 \|\| (ext.rsv3 && ext.name);
			},

			_reserved: function(ext) {
			if (this._rsv1 && ext.rsv1) return [1, this._rsv1];
			if (this._rsv2 && ext.rsv2) return [2, this._rsv2];
			if (this._rsv3 && ext.rsv3) return [3, this._rsv3];
			return false;
			}
			};

			for (var key in instance)
			Extensions.prototype[key] = instance[key];

			module.exports = Extensions;