/**
 * Copyright 2017 Matt Acosta
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { IHashable } from '@mattacosta/php-common';
/**
 * An entry in the object cache hash table.
 *
 * This class is really just a minor optimization to prevent recalculating
 * the hash code of the stored value.
 *
 * @template T
 */
export declare class ObjectCacheEntry<T> {
    readonly hashCode: number;
    readonly value: T;
    /**
     * Constructs an `ObjectCacheEntry<T>` object.
     *
     * @param {number} hashCode
     *   The hash code of the object.
     * @param {T} value
     *   The object.
     */
    constructor(hashCode: number, value: T);
}
/**
 * Provides a cache for storing objects.
 *
 * @template T
 */
export declare class ObjectCache<T extends IHashable<object>> {
    /**
     * A hash table storing cached nodes.
     */
    protected cache: Array<ObjectCacheEntry<T> | undefined>;
    /**
     * A bit mask used to get the lowest n-bits of a hash code.
     *
     * This is used to convert a hash code into a number between `0` and `1 << n`,
     * which is the size of the hash table.
     */
    protected cacheMask: number;
    /**
     * The size of the cache.
     */
    protected cacheSize: number;
    /**
     * Constructs an `ObjectCache` object.
     *
     * @param {number} bitSize
     *   The size of the cache, in bits, so the size will be 2^n.
     */
    constructor(bitSize: number);
    /**
     * Determines if an object has already been cached.
     *
     * NOTE: In order to prevent V8 from dereferencing the value, this method
     * takes the hash code as a parameter. This may be changed in the future.
     */
    has(value: T, hash: number): boolean;
    /**
     * Adds an object to the cache.
     *
     * NOTE: In order to prevent V8 from dereferencing the value, this method
     * takes the hash code as a parameter. This may be changed in the future.
     */
    set(value: T, hash: number): void;
    /**
     * Attempts to get an equivalent object from the cache.
     */
    tryGetObject(value: T, hash: number): T | null;
}