68 lines
1.8 KiB
JavaScript
68 lines
1.8 KiB
JavaScript
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'use strict';
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var mkdirp = require('mkdirp');
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var md5Hex = require('md5-hex');
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var fs = require('fs');
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var path = require('path');
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var writeFileAtomic = require('write-file-atomic');
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function defaultHash(input, additionalData, salt) {
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return md5Hex([input, salt || '']);
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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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var transformFn = opts.transform;
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var factory = opts.factory;
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var cacheDir = opts.cacheDir;
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var cacheDirCreated = opts.createCacheDir === false;
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var created = transformFn && cacheDirCreated;
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var ext = opts.ext || '';
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var salt = opts.salt || '';
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var shouldTransform = opts.shouldTransform;
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var disableCache = opts.disableCache;
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var hashFn = opts.hash || defaultHash;
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var 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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mkdirp.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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var hash = hashFn(input, metadata, salt);
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var cachedPath = path.join(cacheDir, hash + ext);
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try {
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return fs.readFileSync(cachedPath, encoding);
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} catch (e) {
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var result = transform(input, metadata, hash);
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writeFileAtomic.sync(cachedPath, result, encoding);
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return result;
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}
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};
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}
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module.exports = wrap;
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