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