forked from parcel-bundler/parcel
/
serializer.js
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/
serializer.js
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// @flow
import {createBuildCache} from './buildCache';
import {serializeRaw, deserializeRaw} from './serializerCore';
export {serializeRaw, deserializeRaw} from './serializerCore';
const nameToCtor: Map<string, Class<any>> = new Map();
const ctorToName: Map<Class<any>, string> = new Map();
export function registerSerializableClass(name: string, ctor: Class<any>) {
if (ctorToName.has(ctor)) {
throw new Error('Class already registered with serializer');
}
nameToCtor.set(name, ctor);
ctorToName.set(ctor, name);
}
export function unregisterSerializableClass(name: string, ctor: Class<any>) {
if (nameToCtor.get(name) === ctor) {
nameToCtor.delete(name);
}
if (ctorToName.get(ctor) === name) {
ctorToName.delete(ctor);
}
}
function shallowCopy(object: any) {
if (object && typeof object === 'object') {
if (Array.isArray(object)) {
return [...object];
}
if (object instanceof Map) {
return new Map(object);
}
if (object instanceof Set) {
return new Set(object);
}
return Object.create(
Object.getPrototypeOf(object),
Object.getOwnPropertyDescriptors(object),
);
}
return object;
}
function isBuffer(object) {
return (
object.buffer instanceof ArrayBuffer ||
(typeof SharedArrayBuffer !== 'undefined' &&
object.buffer instanceof SharedArrayBuffer)
);
}
function shouldContinueMapping(value) {
return value && typeof value === 'object' && value.$$raw !== true;
}
function mapObject(object: any, fn: (val: any) => any, preOrder = false): any {
let cache = new Map();
let memo = new Map();
// Memoize the passed function to ensure it always returns the exact same
// output by reference for the same input. This is important to maintain
// reference integrity when deserializing rather than cloning.
let memoizedFn = (val: any) => {
let res = memo.get(val);
if (res == null) {
res = fn(val);
memo.set(val, res);
}
return res;
};
let walk = (object: any, shouldCopy = false) => {
// Check the cache first, both for performance and cycle detection.
if (cache.has(object)) {
return cache.get(object);
}
let result = object;
cache.set(object, result);
let processKey = (key: any, value: any) => {
let newValue = value;
if (preOrder && value && typeof value === 'object') {
newValue = memoizedFn(value);
}
// Recursively walk the children
if (
preOrder
? shouldContinueMapping(newValue)
: newValue &&
typeof newValue === 'object' &&
shouldContinueMapping(object)
) {
newValue = walk(newValue, newValue === value);
}
if (!preOrder && newValue && typeof newValue === 'object') {
newValue = memoizedFn(newValue);
}
if (newValue !== value) {
// Copy on write. We only need to do this when serializing, not deserializing.
if (object === result && preOrder && shouldCopy) {
result = shallowCopy(object);
cache.set(object, result);
}
// Replace the key with the new value
if (result instanceof Map) {
result.set(key, newValue);
} else if (result instanceof Set) {
let _result = result; // For Flow
// TODO: do we care about iteration order??
_result.delete(value);
_result.add(newValue);
} else {
result[key] = newValue;
}
}
};
// Iterate in various ways depending on type.
if (Array.isArray(object)) {
for (let i = 0; i < object.length; i++) {
processKey(i, object[i]);
}
} else if (object instanceof Map || object instanceof Set) {
for (let [key, val] of object.entries()) {
processKey(key, val);
}
} else if (!isBuffer(object)) {
for (let key in object) {
processKey(key, object[key]);
}
}
return result;
};
let mapped = memoizedFn(object);
if (
preOrder
? shouldContinueMapping(mapped)
: mapped && typeof mapped === 'object' && shouldContinueMapping(object)
) {
return walk(mapped, mapped === object);
}
return mapped;
}
export function prepareForSerialization(object: any): any {
if (object?.$$raw) {
return object;
}
return mapObject(
object,
value => {
// Add a $$type property with the name of this class, if any is registered.
if (
value &&
typeof value === 'object' &&
typeof value.constructor === 'function'
) {
let type = ctorToName.get(value.constructor);
if (type != null) {
let serialized = value;
let raw = false;
if (value && typeof value.serialize === 'function') {
// If the object has a serialize method, call it
serialized = value.serialize();
raw = (serialized && serialized.$$raw) ?? true;
if (serialized) {
delete serialized.$$raw;
}
}
return {
$$type: type,
$$raw: raw,
value: {...serialized},
};
}
}
return value;
},
true,
);
}
export function restoreDeserializedObject(object: any): any {
return mapObject(object, value => {
// If the value has a $$type property, use it to restore the object type
if (value && value.$$type) {
let ctor = nameToCtor.get(value.$$type);
if (ctor == null) {
throw new Error(
`Expected constructor ${value.$$type} to be registered with serializer to deserialize`,
);
}
if (typeof ctor.deserialize === 'function') {
return ctor.deserialize(value.value);
}
value = value.value;
Object.setPrototypeOf(value, ctor.prototype);
}
return value;
});
}
const serializeCache = createBuildCache();
export function serialize(object: any): Buffer {
let cached = serializeCache.get(object);
if (cached) {
return cached;
}
let mapped = prepareForSerialization(object);
return serializeRaw(mapped);
}
export function deserialize(buffer: Buffer): any {
let obj = deserializeRaw(buffer);
return restoreDeserializedObject(obj);
}
export function cacheSerializedObject(object: any, buffer?: Buffer): void {
serializeCache.set(object, buffer || serialize(object));
}
export function deserializeToCache(buffer: Buffer): any {
let deserialized = deserialize(buffer);
serializeCache.set(deserialized, buffer);
return deserialized;
}
export function removeSerializedObjectFromCache(object: any) {
serializeCache.delete(object);
}