rc-js-util/bin/esm/collection/reference-counter.js

A collection of TS and C++ utilities to help writing performant and correct applications, achieved through strict typing and (removable) invariant checking.

import { fpNoOp } from "../fp/impl/fp-no-op.js";
/**
 * @public
 * Weak reference counter.
 */
export class ReferenceCounter {
    constructor(onZeroReference = fpNoOp) {
        this.onZeroReference = onZeroReference;
        this.store = new WeakMap();
    }
    add(key) {
        let count = this.store.get(key);
        count !== null && count !== void 0 ? count : (count = 0);
        this.store.set(key, ++count);
        return count;
    }
    remove(key) {
        let count = this.store.get(key);
        if (count == null) {
            return 0;
        }
        if (count === 1) {
            this.onZeroReference(key);
            this.store.delete(key);
            return 0;
        }
        this.store.set(key, --count);
        return count;
    }
}
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