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'use strict';
var mkdirp = require('mkdirp');
var md5Hex = require('md5-hex');
var fs = require('fs');
var path = require('path');
var writeFileAtomic = require('write-file-atomic');
function defaultHash(input, additionalData, salt) {
return md5Hex([input, salt || '']);
}
function wrap(opts) {
if (!(opts.factory || opts.transform) || (opts.factory && opts.transform)) {
throw new Error('specify factory or transform but not both');
}
if (typeof opts.cacheDir !== 'string' && !opts.disableCache) {
throw new Error('cacheDir must be a string');
}
var transformFn = opts.transform;
var factory = opts.factory;
var cacheDir = opts.cacheDir;
var cacheDirCreated = opts.createCacheDir === false;
var created = transformFn && cacheDirCreated;
var ext = opts.ext || '';
var salt = opts.salt || '';
var shouldTransform = opts.shouldTransform;
var disableCache = opts.disableCache;
var hashFn = opts.hash || defaultHash;
var encoding = opts.encoding === 'buffer' ? undefined : opts.encoding || 'utf8';
function transform(input, metadata, hash) {
if (!created) {
if (!cacheDirCreated && !disableCache) {
mkdirp.sync(cacheDir);
}
if (!transformFn) {
transformFn = factory(cacheDir);
}
created = true;
}
return transformFn(input, metadata, hash);
}
return function (input, metadata) {
if (shouldTransform && !shouldTransform(input, metadata)) {
return input;
}
if (disableCache) {
return transform(input, metadata);
}
var hash = hashFn(input, metadata, salt);
var cachedPath = path.join(cacheDir, hash + ext);
try {
return fs.readFileSync(cachedPath, encoding);
} catch (e) {
var result = transform(input, metadata, hash);
writeFileAtomic.sync(cachedPath, result, encoding);
return result;
}
};
}
module.exports = wrap;
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