75 lines
1.5 KiB
JavaScript
Executable file
75 lines
1.5 KiB
JavaScript
Executable file
/*
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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("../Cache").Etag} Etag */
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class MergedEtag {
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/**
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* @param {Etag} a first
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* @param {Etag} b second
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*/
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constructor(a, b) {
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this.a = a;
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this.b = b;
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}
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toString() {
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return `${this.a.toString()}|${this.b.toString()}`;
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}
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}
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const dualObjectMap = new WeakMap();
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const objectStringMap = new WeakMap();
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/**
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* @param {Etag} a first
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* @param {Etag} b second
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* @returns {Etag} result
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*/
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const mergeEtags = (a, b) => {
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if (typeof a === "string") {
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if (typeof b === "string") {
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return `${a}|${b}`;
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} else {
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const temp = b;
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b = a;
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a = temp;
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}
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} else {
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if (typeof b !== "string") {
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// both a and b are objects
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let map = dualObjectMap.get(a);
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if (map === undefined) {
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dualObjectMap.set(a, (map = new WeakMap()));
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}
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const mergedEtag = map.get(b);
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if (mergedEtag === undefined) {
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const newMergedEtag = new MergedEtag(a, b);
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map.set(b, newMergedEtag);
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return newMergedEtag;
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} else {
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return mergedEtag;
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}
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}
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}
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// a is object, b is string
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let map = objectStringMap.get(a);
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if (map === undefined) {
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objectStringMap.set(a, (map = new Map()));
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}
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const mergedEtag = map.get(b);
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if (mergedEtag === undefined) {
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const newMergedEtag = new MergedEtag(a, b);
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map.set(b, newMergedEtag);
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return newMergedEtag;
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} else {
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return mergedEtag;
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}
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};
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module.exports = mergeEtags;
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