import Ngram from "../structures/Ngram";
import FrequencyIndex from "./FrequencyIndex";
/**
 * An index of n-gram frequencies
 */
export default class NgramIndex extends FrequencyIndex {
    /**
     * Reads a value from the index
     * @param ngram - the n-gram index to read. This may be a specific key, or the ngram object to read the default key.
     */
    read(ngram: Ngram | string): number;
    /**
     * Writes a value to the index
     * @deprecated - use {@link increment} instead
     * @param {Ngram} ngram - the n-gram index to write
     * @param {number} value
     */
    write(ngram: Ngram, value: number): void;
    /**
     * Increments the n-gram frequency.
     * This will increment all of the important keys in the n-gram such as
     * the words in question, lemma, etc.
     * @param {Ngram} ngram - the n-gram index to add
     * @param {number} value
     */
    increment(ngram: Ngram, value?: number): void;
}