476 lines
17 KiB
JavaScript
476 lines
17 KiB
JavaScript
/**
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* Wrapper around the dirty bits of Bergamot's WASM bindings.
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*/
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// Global because importScripts is global.
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var Module = {};
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/**
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* node.js compatibility: Fake GlobalWorkerScope that emulates being inside a
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* WebWorker
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*/
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if (typeof self === 'undefined') {
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global.Module = Module;
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global.self = new class GlobalWorkerScope {
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/** @type {import("node:worker_threads").MessagePort} */
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#port;
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constructor() {
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const {parentPort} = require(/* webpackIgnore: true */ 'node:worker_threads');
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this.#port = parentPort;
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}
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/**
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* Add event listener to listen for messages posted to the worker.
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* @param {string} eventName
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* @param {(object)} callback
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*/
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addEventListener(eventName, callback) {
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this.#port.on(eventName, (data) => callback({data}));
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}
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/**
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* Post message outside, to the owner of the Worker.
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* @param {any} message
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*/
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postMessage(message) {
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this.#port.postMessage(message);
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}
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/**
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* @param {...string} scripts - Paths to scripts to import in that order
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*/
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importScripts(...scripts) {
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const {readFileSync} = require(/* webpackIgnore: true */ 'node:fs');
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const {join} = require(/* webpackIgnore: true */ 'node:path');
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for (let pathname of scripts) {
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const script = readFileSync(join(__dirname, pathname), {encoding: 'utf-8'});
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eval.call(global, script);
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}
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}
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/**
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* Adds support for local file urls. Assumes anything that doesn't start
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* with "http" to be a local path.
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* @param {string} url - path or url
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* @param {object?} options - See `fetch()` options
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* @return {Promise<Response>}
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*/
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async fetch(url, options) {
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if (url.protocol === 'file:') {
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const {readFile} = require(/* webpackIgnore: true */ 'node:fs/promises');
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const buffer = await readFile(url.pathname);
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const blob = new Blob([buffer]);
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return new Response(blob, {
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status: 200,
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statusText: 'OK',
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headers: {
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'Content-Type': 'application/wasm',
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'Content-Length': blob.size.toString()
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}
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});
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}
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return await fetch(url, options);
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}
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get location() {
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return new URL(`file://${__filename}`);
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}
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}
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}
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class YAML {
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/**
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* Parses YAML into dictionary. Does not interpret types, all values are a
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* string or a list of strings. No support for objects other than the top
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* level.
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* @param {string} yaml
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* @return {{[string]: string | string[]}}
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*/
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static parse(yaml) {
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const out = {};
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yaml.split('\n').reduce((key, line, i) => {
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let match;
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if (match = line.match(/^\s*-\s+(.+?)$/)) {
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if (!Array.isArray(out[key]))
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out[key] = out[key].trim() ? [out[key]] : [];
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out[key].push(match[1].trim());
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}
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else if (match = line.match(/^\s*([A-Za-z0-9_][A-Za-z0-9_-]*):\s*(.*)$/)) {
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key = match[1];
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out[key] = match[2].trim();
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}
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else if (!line.trim()) {
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// whitespace, ignore
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}
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else {
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throw Error(`Could not parse line ${i+1}: "${line}"`);
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}
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return key;
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}, null);
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return out;
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}
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/**
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* Turns an object into a YAML string. No support for objects, only simple
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* types and lists of simple types.
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* @param {{[string]: string | number | boolean | string[]}} data
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* @return {string}
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*/
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static stringify(data) {
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return Object.entries(data).reduce((str, [key, value]) => {
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let valstr = '';
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if (Array.isArray(value))
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valstr = value.map(val => `\n - ${val}`).join('');
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else if (typeof value === 'number' || typeof value === 'boolean' || value.match(/^\d*(\.\d+)?$/))
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valstr = `${value}`;
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else
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valstr = `${value}`; // Quote?
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return `${str}${key}: ${valstr}\n`;
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}, '');
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}
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}
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/**
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* Wrapper around the bergamot-translator exported module that hides the need
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* of working with C++ style data structures and does model management.
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*/
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class BergamotTranslatorWorker {
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/**
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* Map of expected symbol -> name of fallback symbol for functions that can
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* be swizzled for a faster implementation. Firefox Nightly makes use of
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* this.
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*/
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static GEMM_TO_FALLBACK_FUNCTIONS_MAP = {
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'int8_prepare_a': 'int8PrepareAFallback',
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'int8_prepare_b': 'int8PrepareBFallback',
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'int8_prepare_b_from_transposed': 'int8PrepareBFromTransposedFallback',
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'int8_prepare_b_from_quantized_transposed': 'int8PrepareBFromQuantizedTransposedFallback',
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'int8_prepare_bias': 'int8PrepareBiasFallback',
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'int8_multiply_and_add_bias': 'int8MultiplyAndAddBiasFallback',
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'int8_select_columns_of_b': 'int8SelectColumnsOfBFallback'
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};
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/**
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* Name of module exported by Firefox Nightly that exports an optimised
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* implementation of the symbols mentioned above.
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*/
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static NATIVE_INT_GEMM = 'mozIntGemm';
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/**
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* Empty because we can't do async constructors yet. It is the
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* responsibility of whoever owns this WebWorker to call `initialize()`.
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*/
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constructor(options) {}
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/**
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* Instantiates a new translation worker with optional options object.
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* If this call succeeds, the WASM runtime is loaded and ready.
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*
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* Available options are:
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* useNativeIntGemm: {true | false} defaults to false. If true, it will
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* attempt to link to the intgemm module available in
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* Firefox Nightly which makes translations much faster.
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* cacheSize: {Number} defaults to 0 which disables translation
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* cache entirely. Note that this is a theoretical
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* upper bound. In practice it will use about 1/3th of
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* the cache specified here. 2^14 is not a bad starting
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* value.
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* @param {{useNativeIntGemm: boolean, cacheSize: number}} options
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*/
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async initialize(options) {
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this.options = options || {};
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this.models = new Map(); // Map<str,Promise<TranslationModel>>
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this.module = await this.loadModule();
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this.service = await this.loadTranslationService();
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}
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/**
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* Tries to load native IntGEMM module for bergamot-translator. If that
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* fails because it or any of the expected functions is not available, it
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* falls back to using the naive implementations that come with the wasm
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* binary itself through `linkFallbackIntGemm()`.
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* @param {{env: {memory: WebAssembly.Memory}}} info
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* @return {{[method:string]: (...any) => any}}
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*/
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linkNativeIntGemm(info) {
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if (!WebAssembly['mozIntGemm']) {
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console.warn('Native gemm requested but not available, falling back to embedded gemm');
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return this.linkFallbackIntGemm(info);
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}
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const instance = new WebAssembly.Instance(WebAssembly['mozIntGemm'](), {
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'': {memory: info['env']['memory']}
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});
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if (!Array.from(Object.keys(BergamotTranslatorWorker.GEMM_TO_FALLBACK_FUNCTIONS_MAP)).every(fun => instance.exports[fun])) {
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console.warn('Native gemm is missing expected functions, falling back to embedded gemm');
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return this.linkFallbackIntGemm(info);
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}
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return instance.exports;
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}
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/**
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* Links intgemm functions that are already available in the wasm binary,
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* but just exports them under the name that is expected by
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* bergamot-translator.
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* @param {{env: {memory: WebAssembly.Memory}}} info
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* @return {{[method:string]: (...any) => any}}
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*/
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linkFallbackIntGemm(info) {
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const mapping = Object.entries(BergamotTranslatorWorker.GEMM_TO_FALLBACK_FUNCTIONS_MAP).map(([key, name]) => {
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return [key, (...args) => Module['asm'][name](...args)]
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});
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return Object.fromEntries(mapping);
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}
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/**
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* Internal method. Reads and instantiates the WASM binary. Returns a
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* promise for the exported Module object that contains all the classes
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* and functions exported by bergamot-translator.
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* @return {Promise<BergamotTranslator>}
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*/
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loadModule() {
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return new Promise(async (resolve, reject) => {
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try {
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const response = await self.fetch(new URL('./bergamot-translator-worker.wasm', self.location));
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Object.assign(Module, {
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instantiateWasm: (info, accept) => {
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try {
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WebAssembly.instantiateStreaming(response, {
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...info,
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'wasm_gemm': this.options.useNativeIntGemm
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? this.linkNativeIntGemm(info)
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: this.linkFallbackIntGemm(info)
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}).then(({instance}) => accept(instance)).catch(reject);
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} catch (err) {
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reject(err);
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}
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return {};
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},
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onRuntimeInitialized: () => {
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resolve(Module);
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}
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});
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// Emscripten glue code. Webpack et al. should not mangle the `Module` property name!
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self.Module = Module;
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self.importScripts('bergamot-translator-worker.js');
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} catch (err) {
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reject(err);
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}
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});
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}
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/**
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* Internal method. Instantiates a BlockingService()
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* @return {BergamotTranslator.BlockingService}
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*/
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loadTranslationService() {
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return new this.module.BlockingService({
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cacheSize: Math.max(this.options.cacheSize || 0, 0)
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});
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}
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/**
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* Returns whether a model has already been loaded in this worker. Marked
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* async because the message passing interface we use expects async methods.
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* @param {{from:string, to:string}}
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* @return boolean
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*/
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hasTranslationModel({from,to}) {
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const key = JSON.stringify({from,to});
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return this.models.has(key);
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}
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/**
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* Loads a translation model from a set of file buffers. After this, the
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* model is available to translate with and `hasTranslationModel()` will
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* return true for this pair.
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* @param {{from:string, to:string}}
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* @param {{
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* model: ArrayBuffer,
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* shortlist: ArrayBuffer,
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* vocabs: ArrayBuffer[],
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* qualityModel: ArrayBuffer?,
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* config?: {
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* [key:string]: string
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* }
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* }} buffers
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*/
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loadTranslationModel({from, to}, buffers) {
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// This because service_bindings.cpp:prepareVocabsSmartMemories :(
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const uniqueVocabs = buffers.vocabs.filter((vocab, index, vocabs) => {
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return !vocabs.slice(0, index).includes(vocab);
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});
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const [modelMemory, shortlistMemory, qualityModel, ...vocabMemory] = [
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this.prepareAlignedMemoryFromBuffer(buffers.model, 256),
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this.prepareAlignedMemoryFromBuffer(buffers.shortlist, 64),
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buffers.qualityModel // optional quality model
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? this.prepareAlignedMemoryFromBuffer(buffers.qualityModel, 64)
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: null,
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...uniqueVocabs.map(vocab => this.prepareAlignedMemoryFromBuffer(vocab, 64))
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];
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const vocabs = new this.module.AlignedMemoryList();
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vocabMemory.forEach(vocab => vocabs.push_back(vocab));
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// Defaults
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let modelConfig = YAML.parse(`
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beam-size: 1
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normalize: 1.0
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word-penalty: 0
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cpu-threads: 0
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gemm-precision: int8shiftAlphaAll
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skip-cost: true
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`);
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if (buffers.config)
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Object.assign(modelConfig, buffers.config);
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// WASM marian is only compiled with support for shiftedAll.
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if (modelConfig['gemm-precision'] === 'int8')
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modelConfig['gemm-precision'] = 'int8shiftAll';
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// Override these
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Object.assign(modelConfig, YAML.parse(`
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alignment: soft
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quiet: true
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quiet-translation: true
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max-length-break: 128
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mini-batch-words: 1024
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workspace: 128
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max-length-factor: 2.0
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`));
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const key = JSON.stringify({from,to});
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this.models.set(key, new this.module.TranslationModel(YAML.stringify(modelConfig), modelMemory, shortlistMemory, vocabs, qualityModel));
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}
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/**
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* Frees up memory used by old translation model. Does nothing if model is
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* already deleted.
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* @param {{from:string, to:string}}
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*/
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freeTranslationModel({from, to}) {
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const key = JSON.stringify({from,to});
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if (!this.models.has(key))
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return;
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const model = this.models.get(key);
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this.models.delete(key);
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model.delete();
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}
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/**
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* Internal function. Copies the data from an ArrayBuffer into memory that
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* can be used inside the WASM vm by Marian.
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* @param {{ArrayBuffer}} buffer
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* @param {number} alignmentSize
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* @return {BergamotTranslator.AlignedMemory}
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*/
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prepareAlignedMemoryFromBuffer(buffer, alignmentSize) {
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const bytes = new Int8Array(buffer);
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const memory = new this.module.AlignedMemory(bytes.byteLength, alignmentSize);
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memory.getByteArrayView().set(bytes);
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return memory;
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}
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/**
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* Public. Does actual translation work. You have to make sure that the
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* models necessary for translating text are already loaded before calling
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* this method. Returns a promise with translation responses.
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* @param {{models: {from:string, to:string}[], texts: {text: string, html: boolean}[]}}
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* @return {Promise<{target: {text: string}}[]>}
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*/
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translate({models, texts}) {
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// Convert texts array into a std::vector<std::string>.
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let input = new this.module.VectorString();
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texts.forEach(({text}) => input.push_back(text));
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// Extracts the texts[].html options into ResponseOption objects
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let options = new this.module.VectorResponseOptions();
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texts.forEach(({html, qualityScores}) => options.push_back({alignment: false, html, qualityScores}));
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// Turn our model names into a list of TranslationModel pointers
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const translationModels = models.map(({from,to}) => {
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const key = JSON.stringify({from,to});
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return this.models.get(key);
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});
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// translate the input, which is a vector<String>; the result is a vector<Response>
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const responses = models.length > 1
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? this.service.translateViaPivoting(...translationModels, input, options)
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: this.service.translate(...translationModels, input, options);
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input.delete();
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options.delete();
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// Convert the Response WASM wrappers into native JavaScript types we
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// can send over the 'wire' (message passing) in the same format as we
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// use in bergamot-translator.
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const translations = texts.map((_, i) => ({
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target: {
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text: responses.get(i).getTranslatedText()
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}
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}));
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responses.delete();
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return translations;
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}
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}
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/**
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* Because you can't put an Error object in a message. But you can post a
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* generic object!
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* @param {Error} error
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* @return {{
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* name: string?,
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* message: string?,
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* stack: string?
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* }}
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*/
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function cloneError(error) {
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return {
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name: error.name,
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message: error.message,
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stack: error.stack
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};
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}
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// (Constructor doesn't really do anything, we need to call `initialize()`
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// first before using it. That happens from outside the worker.)
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const worker = new BergamotTranslatorWorker();
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self.addEventListener('message', async function({data: {id, name, args}}) {
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if (!id)
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console.error('Received message without id', arguments[0]);
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try {
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if (typeof worker[name] !== 'function')
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throw TypeError(`worker[${name}] is not a function`);
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// Using `Promise.resolve` to await any promises that worker[name]
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// possibly returns.
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const result = await Promise.resolve(Reflect.apply(worker[name], worker, args));
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self.postMessage({id, result});
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} catch (error) {
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self.postMessage({
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id,
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error: cloneError(error)
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})
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}
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});
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