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preserves
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Another small refinement

This commit is contained in:
Tony Garnock-Jones 2024-03-28 11:03:02 +01:00
parent 99d1acdec7
commit 6bc159e3c6
1 changed files with 7 additions and 5 deletions
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12
implementations/javascript/packages/core/src/jsdictionary.ts
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@ -1,5 +1,4 @@
import { Equivalence, IsMap, _iterMap } from './flex';
import { Dictionary, DictionaryType } from './dictionary';
import { Equivalence, _iterMap } from './flex';
export interface JsDictionary<V> {
[key: string]: V;
@ -7,9 +6,12 @@ export interface JsDictionary<V> {
export namespace JsDictionary {
export function isJsDictionary<V>(x: any): x is JsDictionary<V> {
// We accept only literal objects and objects created via `new Object`
// as dictionaries.
return Object.getPrototypeOf(Object.getPrototypeOf(x ?? false)) === null;
// We accept only literal objects and objects created via `new Object` as dictionaries.
// Furthermore, we require no function-valued `__as_preserve__` property to exist.
return typeof x === 'object'
&& x !== null
&& Object.getPrototypeOf(Object.getPrototypeOf(x)) === null
&& typeof x.__as_preserve__ !== 'function';
}
export function from<V>(entries: Iterable<[symbol, V]>): JsDictionary<V> {