103 lines
2.4 KiB
JavaScript
103 lines
2.4 KiB
JavaScript
'use strict';
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const fs = require('fs');
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const path = require('path');
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const hasha = require('hasha');
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const makeDir = require('make-dir');
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const writeFileAtomic = require('write-file-atomic');
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const packageHash = require('package-hash');
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let ownHash = '';
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function getOwnHash() {
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ownHash = packageHash.sync(path.join(__dirname, 'package.json'));
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return ownHash;
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}
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function wrap(opts) {
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if (!(opts.factory || opts.transform) || (opts.factory && opts.transform)) {
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throw new Error('Specify factory or transform but not both');
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}
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if (typeof opts.cacheDir !== 'string' && !opts.disableCache) {
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throw new Error('cacheDir must be a string');
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}
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opts = {
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ext: '',
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salt: '',
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hashData: () => [],
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filenamePrefix: () => '',
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onHash: () => {},
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...opts
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};
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let transformFn = opts.transform;
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const {factory, cacheDir, shouldTransform, disableCache, hashData, onHash, filenamePrefix, ext, salt} = opts;
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const cacheDirCreated = opts.createCacheDir === false;
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let created = transformFn && cacheDirCreated;
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const encoding = opts.encoding === 'buffer' ? undefined : opts.encoding || 'utf8';
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function transform(input, metadata, hash) {
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if (!created) {
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if (!cacheDirCreated && !disableCache) {
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makeDir.sync(cacheDir);
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}
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if (!transformFn) {
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transformFn = factory(cacheDir);
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}
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created = true;
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}
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return transformFn(input, metadata, hash);
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}
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return function (input, metadata) {
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if (shouldTransform && !shouldTransform(input, metadata)) {
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return input;
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}
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if (disableCache) {
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return transform(input, metadata);
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}
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const data = [
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ownHash || getOwnHash(),
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input,
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salt,
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...[].concat(hashData(input, metadata))
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];
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const hash = hasha(data, {algorithm: 'sha256'});
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const cachedPath = path.join(cacheDir, filenamePrefix(metadata) + hash + ext);
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onHash(input, metadata, hash);
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let result;
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let retry = 0;
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/* eslint-disable-next-line no-constant-condition */
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while (true) {
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try {
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return fs.readFileSync(cachedPath, encoding);
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} catch (readError) {
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if (!result) {
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result = transform(input, metadata, hash);
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}
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try {
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writeFileAtomic.sync(cachedPath, result, {encoding});
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return result;
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} catch (error) {
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/* Likely https://github.com/npm/write-file-atomic/issues/28
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* Make up to 3 attempts to read or write the cache. */
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retry++;
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if (retry > 3) {
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throw error;
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}
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}
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}
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}
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};
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}
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module.exports = wrap;
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