buildDocs/utils/CompositeKeyWeakMap.js

import { isUndefined } from 'lodash';
/**
 * A map for weakly holding nested references.
 * @private
 * @export
 * @class CompositeKeyWeakMap
 * @template T
 */
export class CompositeKeyWeakMap {
    constructor() {
        this._weakMap = new WeakMap();
    }
    set(keys, value) {
        let map = this._weakMap;
        for (let i = 0, len = keys.length - 1; i < len; i++) {
            const key = keys[i];
            let next = map.get(key);
            if (!next) {
                next = new Map();
                map.set(key, next);
            }
            map = next;
        }
        map.set(keys[keys.length - 1], value);
    }
    get(keys) {
        let next = this._weakMap;
        for (let i = 0, len = keys.length; i < len; i++) {
            next = next.get(keys[i]);
            if (isUndefined(next)) {
                break;
            }
        }
        return next;
    }
    has(keys) {
        return !isUndefined(this.get(keys));
    }
}