import Alignment from "../structures/Alignment";
import AlignmentIndex from "./AlignmentIndex";
import NgramIndex from "./NgramIndex";
/**
 * A collection of indexes on the permutation of possible alignments.
 */
export default class PermutationIndex {
    /**
     * Alignment permutation frequency index.
     * The total number of occurrences within the alignment permutations.
     */
    private alignPermFreqIndex;
    /**
     * Source n-gram permutation frequency index.
     * The total number of occurrences within the alignment permutations.
     */
    private srcNgramPermFreqIndex;
    /**
     * Target n-gram permuation frequency index.
     * The total number of occurrences within the alignment permutations.
     */
    private tgtNgramPermFreqIndex;
    /**
     * Returns an index of alignment frequencies in the permutations
     */
    readonly alignmentFrequency: AlignmentIndex;
    /**
     * Returns an index of source n-gram frequencies in the permutations
     * @return {NgramIndex}
     */
    readonly sourceNgramFrequency: NgramIndex;
    /**
     * Returns an index of target n-gram frequencies in the permutations
     * @return {NgramIndex}
     */
    readonly targetNgramFrequency: NgramIndex;
    constructor();
    /**
     * Adds a sentence alignment to the index.
     * @param {Alignment[]} alignments - an array of alignments to add
     */
    addAlignments(alignments: Alignment[]): void;
    /**
     * Adds a single alignment to the index
     * @param alignment
     */
    addAlignment(alignment: Alignment): void;
}