86 lines
2.3 KiB
JavaScript
86 lines
2.3 KiB
JavaScript
"use strict";
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var USE_TYPEDARRAY = (typeof Uint8Array !== "undefined") && (typeof Uint16Array !== "undefined") && (typeof Uint32Array !== "undefined");
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var pako = require("pako");
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var utils = require("./utils");
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var GenericWorker = require("./stream/GenericWorker");
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var ARRAY_TYPE = USE_TYPEDARRAY ? "uint8array" : "array";
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exports.magic = "\x08\x00";
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/**
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* Create a worker that uses pako to inflate/deflate.
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* @constructor
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* @param {String} action the name of the pako function to call : either "Deflate" or "Inflate".
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* @param {Object} options the options to use when (de)compressing.
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*/
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function FlateWorker(action, options) {
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GenericWorker.call(this, "FlateWorker/" + action);
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this._pako = null;
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this._pakoAction = action;
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this._pakoOptions = options;
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// the `meta` object from the last chunk received
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// this allow this worker to pass around metadata
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this.meta = {};
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}
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utils.inherits(FlateWorker, GenericWorker);
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/**
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* @see GenericWorker.processChunk
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*/
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FlateWorker.prototype.processChunk = function (chunk) {
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this.meta = chunk.meta;
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if (this._pako === null) {
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this._createPako();
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}
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this._pako.push(utils.transformTo(ARRAY_TYPE, chunk.data), false);
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};
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/**
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* @see GenericWorker.flush
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*/
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FlateWorker.prototype.flush = function () {
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GenericWorker.prototype.flush.call(this);
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if (this._pako === null) {
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this._createPako();
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}
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this._pako.push([], true);
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};
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/**
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* @see GenericWorker.cleanUp
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*/
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FlateWorker.prototype.cleanUp = function () {
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GenericWorker.prototype.cleanUp.call(this);
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this._pako = null;
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};
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/**
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* Create the _pako object.
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* TODO: lazy-loading this object isn't the best solution but it's the
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* quickest. The best solution is to lazy-load the worker list. See also the
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* issue #446.
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*/
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FlateWorker.prototype._createPako = function () {
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this._pako = new pako[this._pakoAction]({
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raw: true,
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level: this._pakoOptions.level || -1 // default compression
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});
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var self = this;
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this._pako.onData = function(data) {
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self.push({
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data : data,
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meta : self.meta
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});
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};
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};
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exports.compressWorker = function (compressionOptions) {
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return new FlateWorker("Deflate", compressionOptions);
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};
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exports.uncompressWorker = function () {
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return new FlateWorker("Inflate", {});
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};
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