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