1 | /*
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2 | MIT License http://www.opensource.org/licenses/mit-license.php
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3 | Author Tobias Koppers @sokra
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4 | */
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5 |
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6 | "use strict";
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7 |
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8 | /** @typedef {import("../Cache").Etag} Etag */
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9 |
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10 | class MergedEtag {
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11 | /**
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12 | * @param {Etag} a first
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13 | * @param {Etag} b second
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14 | */
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15 | constructor(a, b) {
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16 | this.a = a;
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17 | this.b = b;
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18 | }
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19 |
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20 | toString() {
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21 | return `${this.a.toString()}|${this.b.toString()}`;
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22 | }
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23 | }
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24 |
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25 | const dualObjectMap = new WeakMap();
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26 | const objectStringMap = new WeakMap();
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27 |
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28 | /**
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29 | * @param {Etag} a first
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30 | * @param {Etag} b second
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31 | * @returns {Etag} result
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32 | */
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33 | const mergeEtags = (a, b) => {
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34 | if (typeof a === "string") {
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35 | if (typeof b === "string") {
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36 | return `${a}|${b}`;
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37 | } else {
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38 | const temp = b;
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39 | b = a;
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40 | a = temp;
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41 | }
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42 | } else {
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43 | if (typeof b !== "string") {
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44 | // both a and b are objects
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45 | let map = dualObjectMap.get(a);
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46 | if (map === undefined) {
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47 | dualObjectMap.set(a, (map = new WeakMap()));
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48 | }
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49 | const mergedEtag = map.get(b);
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50 | if (mergedEtag === undefined) {
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51 | const newMergedEtag = new MergedEtag(a, b);
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52 | map.set(b, newMergedEtag);
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53 | return newMergedEtag;
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54 | } else {
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55 | return mergedEtag;
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56 | }
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57 | }
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58 | }
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59 | // a is object, b is string
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60 | let map = objectStringMap.get(a);
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61 | if (map === undefined) {
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62 | objectStringMap.set(a, (map = new Map()));
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63 | }
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64 | const mergedEtag = map.get(b);
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65 | if (mergedEtag === undefined) {
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66 | const newMergedEtag = new MergedEtag(a, b);
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67 | map.set(b, newMergedEtag);
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68 | return newMergedEtag;
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69 | } else {
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70 | return mergedEtag;
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71 | }
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72 | };
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73 |
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74 | module.exports = mergeEtags;
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