mirror of https://github.com/jkjoy/sunpeiwen.git
58 lines
2.1 KiB
JavaScript
58 lines
2.1 KiB
JavaScript
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'use strict';
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var wrapIdbValue = require('./wrap-idb-value.cjs');
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const advanceMethodProps = ['continue', 'continuePrimaryKey', 'advance'];
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const methodMap = {};
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const advanceResults = new WeakMap();
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const ittrProxiedCursorToOriginalProxy = new WeakMap();
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const cursorIteratorTraps = {
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get(target, prop) {
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if (!advanceMethodProps.includes(prop))
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return target[prop];
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let cachedFunc = methodMap[prop];
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if (!cachedFunc) {
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cachedFunc = methodMap[prop] = function (...args) {
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advanceResults.set(this, ittrProxiedCursorToOriginalProxy.get(this)[prop](...args));
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};
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}
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return cachedFunc;
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},
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};
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async function* iterate(...args) {
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// tslint:disable-next-line:no-this-assignment
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let cursor = this;
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if (!(cursor instanceof IDBCursor)) {
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cursor = await cursor.openCursor(...args);
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}
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if (!cursor)
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return;
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cursor = cursor;
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const proxiedCursor = new Proxy(cursor, cursorIteratorTraps);
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ittrProxiedCursorToOriginalProxy.set(proxiedCursor, cursor);
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// Map this double-proxy back to the original, so other cursor methods work.
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wrapIdbValue.reverseTransformCache.set(proxiedCursor, wrapIdbValue.unwrap(cursor));
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while (cursor) {
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yield proxiedCursor;
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// If one of the advancing methods was not called, call continue().
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cursor = await (advanceResults.get(proxiedCursor) || cursor.continue());
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advanceResults.delete(proxiedCursor);
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}
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}
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function isIteratorProp(target, prop) {
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return ((prop === Symbol.asyncIterator &&
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wrapIdbValue.instanceOfAny(target, [IDBIndex, IDBObjectStore, IDBCursor])) ||
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(prop === 'iterate' && wrapIdbValue.instanceOfAny(target, [IDBIndex, IDBObjectStore])));
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}
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wrapIdbValue.replaceTraps((oldTraps) => ({
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...oldTraps,
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get(target, prop, receiver) {
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if (isIteratorProp(target, prop))
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return iterate;
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return oldTraps.get(target, prop, receiver);
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},
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has(target, prop) {
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return isIteratorProp(target, prop) || oldTraps.has(target, prop);
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},
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}));
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