75 lines
2.8 KiB
JavaScript
75 lines
2.8 KiB
JavaScript
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"use strict";
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var external = require("./external");
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var DataWorker = require("./stream/DataWorker");
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var Crc32Probe = require("./stream/Crc32Probe");
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var DataLengthProbe = require("./stream/DataLengthProbe");
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/**
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* Represent a compressed object, with everything needed to decompress it.
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* @constructor
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* @param {number} compressedSize the size of the data compressed.
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* @param {number} uncompressedSize the size of the data after decompression.
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* @param {number} crc32 the crc32 of the decompressed file.
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* @param {object} compression the type of compression, see lib/compressions.js.
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* @param {String|ArrayBuffer|Uint8Array|Buffer} data the compressed data.
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*/
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function CompressedObject(compressedSize, uncompressedSize, crc32, compression, data) {
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this.compressedSize = compressedSize;
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this.uncompressedSize = uncompressedSize;
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this.crc32 = crc32;
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this.compression = compression;
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this.compressedContent = data;
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}
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CompressedObject.prototype = {
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/**
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* Create a worker to get the uncompressed content.
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* @return {GenericWorker} the worker.
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*/
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getContentWorker: function () {
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var worker = new DataWorker(external.Promise.resolve(this.compressedContent))
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.pipe(this.compression.uncompressWorker())
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.pipe(new DataLengthProbe("data_length"));
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var that = this;
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worker.on("end", function () {
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if (this.streamInfo["data_length"] !== that.uncompressedSize) {
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throw new Error("Bug : uncompressed data size mismatch");
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}
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});
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return worker;
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},
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/**
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* Create a worker to get the compressed content.
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* @return {GenericWorker} the worker.
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*/
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getCompressedWorker: function () {
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return new DataWorker(external.Promise.resolve(this.compressedContent))
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.withStreamInfo("compressedSize", this.compressedSize)
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.withStreamInfo("uncompressedSize", this.uncompressedSize)
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.withStreamInfo("crc32", this.crc32)
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.withStreamInfo("compression", this.compression)
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;
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}
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};
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/**
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* Chain the given worker with other workers to compress the content with the
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* given compression.
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* @param {GenericWorker} uncompressedWorker the worker to pipe.
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* @param {Object} compression the compression object.
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* @param {Object} compressionOptions the options to use when compressing.
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* @return {GenericWorker} the new worker compressing the content.
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*/
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CompressedObject.createWorkerFrom = function (uncompressedWorker, compression, compressionOptions) {
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return uncompressedWorker
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.pipe(new Crc32Probe())
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.pipe(new DataLengthProbe("uncompressedSize"))
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.pipe(compression.compressWorker(compressionOptions))
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.pipe(new DataLengthProbe("compressedSize"))
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.withStreamInfo("compression", compression);
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};
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module.exports = CompressedObject;
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