56 lines
1.3 KiB
TypeScript
56 lines
1.3 KiB
TypeScript
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import { Key, KeyPath, Value } from "./types";
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import valueToKey from "./valueToKey";
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// http://www.w3.org/TR/2015/REC-IndexedDB-20150108/#dfn-steps-for-extracting-a-key-from-a-value-using-a-key-path
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const extractKey = (keyPath: KeyPath, value: Value) => {
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if (Array.isArray(keyPath)) {
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const result: Key[] = [];
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for (let item of keyPath) {
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// This doesn't make sense to me based on the spec, but it is needed to pass the W3C KeyPath tests (see same
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// comment in validateKeyPath)
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if (
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item !== undefined &&
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item !== null &&
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typeof item !== "string" &&
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(item as any).toString
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) {
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item = (item as any).toString();
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}
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result.push(valueToKey(extractKey(item, value)));
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}
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return result;
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}
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if (keyPath === "") {
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return value;
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}
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let remainingKeyPath: string | null = keyPath;
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let object = value;
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while (remainingKeyPath !== null) {
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let identifier;
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const i = remainingKeyPath.indexOf(".");
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if (i >= 0) {
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identifier = remainingKeyPath.slice(0, i);
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remainingKeyPath = remainingKeyPath.slice(i + 1);
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} else {
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identifier = remainingKeyPath;
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remainingKeyPath = null;
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}
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if (!object.hasOwnProperty(identifier)) {
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return;
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}
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object = object[identifier];
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}
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return object;
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};
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export default extractKey;
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