mirror of https://github.com/webpack/webpack.git
62 lines
1.7 KiB
JavaScript
62 lines
1.7 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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/** @typedef {import("webpack-sources").Source} Source */
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/** @type {WeakMap<Source, WeakMap<Source, boolean>>} */
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const equalityCache = new WeakMap();
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/**
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* @param {Source} a a source
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* @param {Source} b another source
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* @returns {boolean} true, when both sources are equal
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*/
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const _isSourceEqual = (a, b) => {
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// prefer .buffer(), it's called anyway during emit
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/** @type {Buffer|string} */
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let aSource = typeof a.buffer === "function" ? a.buffer() : a.source();
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/** @type {Buffer|string} */
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let bSource = typeof b.buffer === "function" ? b.buffer() : b.source();
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if (aSource === bSource) return true;
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if (typeof aSource === "string" && typeof bSource === "string") return false;
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if (!Buffer.isBuffer(aSource)) aSource = Buffer.from(aSource, "utf-8");
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if (!Buffer.isBuffer(bSource)) bSource = Buffer.from(bSource, "utf-8");
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return aSource.equals(bSource);
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};
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/**
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* @param {Source} a a source
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* @param {Source} b another source
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* @returns {boolean} true, when both sources are equal
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*/
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const isSourceEqual = (a, b) => {
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if (a === b) return true;
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const cache1 = equalityCache.get(a);
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if (cache1 !== undefined) {
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const result = cache1.get(b);
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if (result !== undefined) return result;
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}
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const result = _isSourceEqual(a, b);
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if (cache1 !== undefined) {
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cache1.set(b, result);
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} else {
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const map = new WeakMap();
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map.set(b, result);
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equalityCache.set(a, map);
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}
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const cache2 = equalityCache.get(b);
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if (cache2 !== undefined) {
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cache2.set(a, result);
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} else {
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const map = new WeakMap();
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map.set(a, result);
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equalityCache.set(b, map);
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}
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return result;
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};
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module.exports.isSourceEqual = isSourceEqual;
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