63 lines
2.1 KiB
JavaScript
63 lines
2.1 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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this.EXPORTED_SYMBOLS = ["CanonicalJSON"];
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const { classes: Cc, interfaces: Ci, utils: Cu } = Components;
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Cu.import("resource://gre/modules/XPCOMUtils.jsm");
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XPCOMUtils.defineLazyModuleGetter(this, "jsesc",
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"resource://gre/modules/third_party/jsesc/jsesc.js");
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this.CanonicalJSON = {
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/**
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* Return the canonical JSON form of the passed source, sorting all the object
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* keys recursively. Note that this method will cause an infinite loop if
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* cycles exist in the source (bug 1265357).
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*
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* @param source
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* The elements to be serialized.
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*
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* The output will have all unicode chars escaped with the unicode codepoint
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* as lowercase hexadecimal.
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*
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* @usage
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* CanonicalJSON.stringify(listOfRecords);
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**/
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stringify: function stringify(source) {
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if (Array.isArray(source)) {
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const jsonArray = source.map(x => typeof x === "undefined" ? null : x);
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return `[${jsonArray.map(stringify).join(",")}]`;
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}
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if (typeof source === "number") {
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if (source === 0) {
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return (Object.is(source, -0)) ? "-0" : "0";
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}
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}
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// Leverage jsesc library, mainly for unicode escaping.
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const toJSON = (input) => jsesc(input, {lowercaseHex: true, json: true});
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if (typeof source !== "object" || source === null) {
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return toJSON(source);
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}
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// Dealing with objects, ordering keys.
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const sortedKeys = Object.keys(source).sort();
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const lastIndex = sortedKeys.length - 1;
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return sortedKeys.reduce((serial, key, index) => {
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const value = source[key];
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// JSON.stringify drops keys with an undefined value.
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if (typeof value === "undefined") {
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return serial;
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}
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const jsonValue = value && value.toJSON ? value.toJSON() : value;
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const suffix = index !== lastIndex ? "," : "";
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const escapedKey = toJSON(key);
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return serial + `${escapedKey}:${stringify(jsonValue)}${suffix}`;
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}, "{") + "}";
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},
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};
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