mirror of https://github.com/webpack/webpack.git
55 lines
1.1 KiB
JavaScript
55 lines
1.1 KiB
JavaScript
/*
|
|
MIT License http://www.opensource.org/licenses/mit-license.php
|
|
Author Tobias Koppers @sokra
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
const createHash = require("../util/createHash");
|
|
|
|
/** @typedef {import("../util/Hash")} Hash */
|
|
|
|
/**
|
|
* @typedef {Object} HashableObject
|
|
* @property {function(Hash): void} updateHash
|
|
*/
|
|
|
|
class LazyHashedEtag {
|
|
/**
|
|
* @param {HashableObject} obj object with updateHash method
|
|
*/
|
|
constructor(obj) {
|
|
this._obj = obj;
|
|
this._hash = undefined;
|
|
}
|
|
|
|
/**
|
|
* @returns {string} hash of object
|
|
*/
|
|
toString() {
|
|
if (this._hash === undefined) {
|
|
const hash = createHash("md4");
|
|
this._obj.updateHash(hash);
|
|
this._hash = /** @type {string} */ (hash.digest("base64"));
|
|
}
|
|
return this._hash;
|
|
}
|
|
}
|
|
|
|
/** @type {WeakMap<HashableObject, LazyHashedEtag>} */
|
|
const map = new WeakMap();
|
|
|
|
/**
|
|
* @param {HashableObject} obj object with updateHash method
|
|
* @returns {LazyHashedEtag} etag
|
|
*/
|
|
const getter = obj => {
|
|
const hash = map.get(obj);
|
|
if (hash !== undefined) return hash;
|
|
const newHash = new LazyHashedEtag(obj);
|
|
map.set(obj, newHash);
|
|
return newHash;
|
|
};
|
|
|
|
module.exports = getter;
|