Created
May 6, 2022 11:58
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Self-referencing JSON to handle recursion, WDYT?
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| function stringify(value) { | |
| const map = new Map(); | |
| function traverse(value, reference) { | |
| if(map.has(value)) | |
| return map.get(value); | |
| if(Array.isArray(value)) { | |
| map.set(value, reference); | |
| let result = ""; | |
| const last = value.length - 1; | |
| for(let i = 0; i <= last; i++) { | |
| result += traverse(value[i], reference + "[" + i + "]"); | |
| if(i !== last) | |
| result += ","; | |
| } | |
| return "[" + result + "]"; | |
| } | |
| if (value !== null && typeof value === "object") { | |
| map.set(value, reference); | |
| const keys = Object.keys(value); | |
| const lastKey = keys[keys.length-1]; | |
| let result = ""; | |
| for (const key of keys) { | |
| result += JSON.stringify(key) + ":" + traverse(value[key], reference + "." + key); | |
| if (key !== lastKey) | |
| result += ","; | |
| } | |
| return "{" + result + "}"; | |
| } | |
| return JSON.stringify(value); | |
| } | |
| return traverse(value, "_"); | |
| } | |
| function parse(text) { | |
| const normalizeKey = key => /^[0-9]+$/.test(key) ? parseInt(key) : key; | |
| const proxies = new Set(); | |
| function proxy(reference) { | |
| const result = new Proxy(() => reference, { | |
| apply:(target, thisArg, [root]) => target().reduce((p, c) => p[normalizeKey(c)], root), | |
| get:(target, property) => proxy([...target(), property]) | |
| }); | |
| proxies.add(result); | |
| return result; | |
| } | |
| function traverse(data) { | |
| if(Array.isArray(data)) { | |
| for(let i = 0; i < data.length; i++) { | |
| const value = data[i]; | |
| if(proxies.has(value)) | |
| data[i] = value(_); | |
| else | |
| traverse(value); | |
| } | |
| } else if (data !== null && typeof data === "object") { | |
| for (const key of Object.keys(data)) { | |
| const value = data[key]; | |
| if(proxies.has(value)) | |
| data[key] = value(_); | |
| else | |
| traverse(value); | |
| } | |
| } | |
| return data; | |
| } | |
| const _ = (new Function("with(this) return " + text)).call({_:proxy([])}); | |
| return traverse(_); | |
| } | |
| let foo = {foo:"bar"}; | |
| let source = [foo, foo]; | |
| source.push(source); | |
| // `_` refers to the object itself | |
| console.log(stringify(source)); // [{"foo":"bar"},_[0],_] | |
| let result = parse('[{"foo":"bar"},_[0],_]'); | |
| console.log(result[0] === result[1]); // true | |
| console.log(result[1].foo === "bar"); // true | |
| console.log(result[2] === result); // true |
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