1 files changed, 67 insertions, 0 deletions
diff --git a/node_modules/caching-transform/index.js b/node_modules/caching-transform/index.js
new file mode 100644
index 000000000..a66a6741d
--- /dev/null
+++ b/node_modules/caching-transform/index.js
@@ -0,0 +1,67 @@
+'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;