kusamoji/src/dict/ConnectionCosts.js

Japanese morphological analyzer for Node.js — Viterbi tokenizer with mmap dict loading and pluggable POS-source strategy

"use strict";

/**
 * Connection costs matrix from cc.dat file.
 * 2 dimension matrix [forward_id][backward_id] -> cost
 * @constructor
 * @param {number} forward_dimension
 * @param {number} backward_dimension
 */
function ConnectionCosts(forward_dimension, backward_dimension) {
    this.forward_dimension = forward_dimension;
    this.backward_dimension = backward_dimension;

    // leading 2 integers for forward_dimension, backward_dimension, respectively
    this.buffer = new Int16Array(forward_dimension * backward_dimension + 2);
    this.buffer[0] = forward_dimension;
    this.buffer[1] = backward_dimension;
}

ConnectionCosts.prototype.put = function (forward_id, backward_id, cost) {
    let index = forward_id * this.backward_dimension + backward_id + 2;
    if (this.buffer.length < index + 1) {
        throw "ConnectionCosts buffer overflow";
    }
    this.buffer[index] = cost;
};

ConnectionCosts.prototype.get = function (forward_id, backward_id) {
    let index = forward_id * this.backward_dimension + backward_id + 2;
    if (this.buffer.length < index + 1) {
        throw "ConnectionCosts buffer overflow";
    }
    return this.buffer[index];
};

ConnectionCosts.prototype.loadConnectionCosts = function (connection_costs_buffer) {
    this.forward_dimension = connection_costs_buffer[0];
    this.backward_dimension = connection_costs_buffer[1];
    this.buffer = connection_costs_buffer;
};

module.exports = ConnectionCosts;