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denoland-deno/cli/js/mixins/dom_iterable.ts
2020-01-21 10:01:55 -05:00

85 lines
2.8 KiB
TypeScript

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
// eslint-disable-next-line @typescript-eslint/no-unused-vars
import { DomIterable } from "../dom_types.ts";
import { requiredArguments } from "../util.ts";
import { exposeForTest } from "../internals.ts";
// eslint-disable-next-line @typescript-eslint/no-explicit-any
type Constructor<T = {}> = new (...args: any[]) => T;
/** Mixes in a DOM iterable methods into a base class, assumes that there is
* a private data iterable that is part of the base class, located at
* `[dataSymbol]`.
*/
export function DomIterableMixin<K, V, TBase extends Constructor>(
Base: TBase,
dataSymbol: symbol
): TBase & Constructor<DomIterable<K, V>> {
// we have to cast `this` as `any` because there is no way to describe the
// Base class in a way where the Symbol `dataSymbol` is defined. So the
// runtime code works, but we do lose a little bit of type safety.
// Additionally, we have to not use .keys() nor .values() since the internal
// slot differs in type - some have a Map, which yields [K, V] in
// Symbol.iterator, and some have an Array, which yields V, in this case
// [K, V] too as they are arrays of tuples.
const DomIterable = class extends Base {
*entries(): IterableIterator<[K, V]> {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
for (const entry of (this as any)[dataSymbol]) {
yield entry;
}
}
*keys(): IterableIterator<K> {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
for (const [key] of (this as any)[dataSymbol]) {
yield key;
}
}
*values(): IterableIterator<V> {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
for (const [, value] of (this as any)[dataSymbol]) {
yield value;
}
}
forEach(
callbackfn: (value: V, key: K, parent: this) => void,
// eslint-disable-next-line @typescript-eslint/no-explicit-any
thisArg?: any
): void {
requiredArguments(
`${this.constructor.name}.forEach`,
arguments.length,
1
);
callbackfn = callbackfn.bind(
thisArg == null ? globalThis : Object(thisArg)
);
// eslint-disable-next-line @typescript-eslint/no-explicit-any
for (const [key, value] of (this as any)[dataSymbol]) {
callbackfn(value, key, this);
}
}
*[Symbol.iterator](): IterableIterator<[K, V]> {
// eslint-disable-next-line @typescript-eslint/no-explicit-any
for (const entry of (this as any)[dataSymbol]) {
yield entry;
}
}
};
// we want the Base class name to be the name of the class.
Object.defineProperty(DomIterable, "name", {
value: Base.name,
configurable: true
});
return DomIterable;
}
exposeForTest("DomIterableMixin", DomIterableMixin);