mirror of https://github.com/jkjoy/sunpeiwen.git
192 lines
7.6 KiB
JavaScript
192 lines
7.6 KiB
JavaScript
'use strict';
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const instanceOfAny = (object, constructors) => constructors.some((c) => object instanceof c);
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let idbProxyableTypes;
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let cursorAdvanceMethods;
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// This is a function to prevent it throwing up in node environments.
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function getIdbProxyableTypes() {
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return (idbProxyableTypes ||
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(idbProxyableTypes = [
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IDBDatabase,
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IDBObjectStore,
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IDBIndex,
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IDBCursor,
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IDBTransaction,
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]));
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}
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// This is a function to prevent it throwing up in node environments.
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function getCursorAdvanceMethods() {
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return (cursorAdvanceMethods ||
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(cursorAdvanceMethods = [
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IDBCursor.prototype.advance,
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IDBCursor.prototype.continue,
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IDBCursor.prototype.continuePrimaryKey,
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]));
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}
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const cursorRequestMap = new WeakMap();
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const transactionDoneMap = new WeakMap();
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const transactionStoreNamesMap = new WeakMap();
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const transformCache = new WeakMap();
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const reverseTransformCache = new WeakMap();
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function promisifyRequest(request) {
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const promise = new Promise((resolve, reject) => {
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const unlisten = () => {
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request.removeEventListener('success', success);
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request.removeEventListener('error', error);
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};
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const success = () => {
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resolve(wrap(request.result));
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unlisten();
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};
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const error = () => {
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reject(request.error);
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unlisten();
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};
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request.addEventListener('success', success);
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request.addEventListener('error', error);
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});
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promise
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.then((value) => {
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// Since cursoring reuses the IDBRequest (*sigh*), we cache it for later retrieval
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// (see wrapFunction).
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if (value instanceof IDBCursor) {
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cursorRequestMap.set(value, request);
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}
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// Catching to avoid "Uncaught Promise exceptions"
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})
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.catch(() => { });
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// This mapping exists in reverseTransformCache but doesn't doesn't exist in transformCache. This
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// is because we create many promises from a single IDBRequest.
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reverseTransformCache.set(promise, request);
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return promise;
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}
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function cacheDonePromiseForTransaction(tx) {
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// Early bail if we've already created a done promise for this transaction.
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if (transactionDoneMap.has(tx))
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return;
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const done = new Promise((resolve, reject) => {
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const unlisten = () => {
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tx.removeEventListener('complete', complete);
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tx.removeEventListener('error', error);
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tx.removeEventListener('abort', error);
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};
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const complete = () => {
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resolve();
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unlisten();
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};
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const error = () => {
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reject(tx.error || new DOMException('AbortError', 'AbortError'));
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unlisten();
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};
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tx.addEventListener('complete', complete);
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tx.addEventListener('error', error);
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tx.addEventListener('abort', error);
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});
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// Cache it for later retrieval.
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transactionDoneMap.set(tx, done);
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}
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let idbProxyTraps = {
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get(target, prop, receiver) {
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if (target instanceof IDBTransaction) {
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// Special handling for transaction.done.
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if (prop === 'done')
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return transactionDoneMap.get(target);
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// Polyfill for objectStoreNames because of Edge.
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if (prop === 'objectStoreNames') {
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return target.objectStoreNames || transactionStoreNamesMap.get(target);
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}
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// Make tx.store return the only store in the transaction, or undefined if there are many.
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if (prop === 'store') {
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return receiver.objectStoreNames[1]
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? undefined
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: receiver.objectStore(receiver.objectStoreNames[0]);
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}
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}
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// Else transform whatever we get back.
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return wrap(target[prop]);
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},
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set(target, prop, value) {
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target[prop] = value;
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return true;
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},
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has(target, prop) {
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if (target instanceof IDBTransaction &&
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(prop === 'done' || prop === 'store')) {
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return true;
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}
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return prop in target;
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},
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};
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function replaceTraps(callback) {
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idbProxyTraps = callback(idbProxyTraps);
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}
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function wrapFunction(func) {
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// Due to expected object equality (which is enforced by the caching in `wrap`), we
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// only create one new func per func.
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// Edge doesn't support objectStoreNames (booo), so we polyfill it here.
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if (func === IDBDatabase.prototype.transaction &&
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!('objectStoreNames' in IDBTransaction.prototype)) {
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return function (storeNames, ...args) {
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const tx = func.call(unwrap(this), storeNames, ...args);
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transactionStoreNamesMap.set(tx, storeNames.sort ? storeNames.sort() : [storeNames]);
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return wrap(tx);
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};
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}
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// Cursor methods are special, as the behaviour is a little more different to standard IDB. In
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// IDB, you advance the cursor and wait for a new 'success' on the IDBRequest that gave you the
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// cursor. It's kinda like a promise that can resolve with many values. That doesn't make sense
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// with real promises, so each advance methods returns a new promise for the cursor object, or
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// undefined if the end of the cursor has been reached.
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if (getCursorAdvanceMethods().includes(func)) {
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return function (...args) {
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// Calling the original function with the proxy as 'this' causes ILLEGAL INVOCATION, so we use
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// the original object.
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func.apply(unwrap(this), args);
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return wrap(cursorRequestMap.get(this));
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};
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}
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return function (...args) {
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// Calling the original function with the proxy as 'this' causes ILLEGAL INVOCATION, so we use
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// the original object.
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return wrap(func.apply(unwrap(this), args));
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};
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}
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function transformCachableValue(value) {
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if (typeof value === 'function')
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return wrapFunction(value);
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// This doesn't return, it just creates a 'done' promise for the transaction,
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// which is later returned for transaction.done (see idbObjectHandler).
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if (value instanceof IDBTransaction)
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cacheDonePromiseForTransaction(value);
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if (instanceOfAny(value, getIdbProxyableTypes()))
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return new Proxy(value, idbProxyTraps);
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// Return the same value back if we're not going to transform it.
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return value;
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}
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function wrap(value) {
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// We sometimes generate multiple promises from a single IDBRequest (eg when cursoring), because
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// IDB is weird and a single IDBRequest can yield many responses, so these can't be cached.
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if (value instanceof IDBRequest)
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return promisifyRequest(value);
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// If we've already transformed this value before, reuse the transformed value.
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// This is faster, but it also provides object equality.
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if (transformCache.has(value))
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return transformCache.get(value);
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const newValue = transformCachableValue(value);
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// Not all types are transformed.
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// These may be primitive types, so they can't be WeakMap keys.
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if (newValue !== value) {
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transformCache.set(value, newValue);
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reverseTransformCache.set(newValue, value);
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}
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return newValue;
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}
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const unwrap = (value) => reverseTransformCache.get(value);
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exports.instanceOfAny = instanceOfAny;
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exports.replaceTraps = replaceTraps;
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exports.reverseTransformCache = reverseTransformCache;
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exports.unwrap = unwrap;
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exports.wrap = wrap;
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