liza/src/util/ShallowArrayDiff.js

/**
 * Performs a strict shallow diff on the values of two arrays
 *
 *  Copyright (C) 2017 R-T Specialty, LLC.
 *
 *  This file is part of the Liza Data Collection Framework.
 *
 *  liza is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

var Class     = require( 'easejs' ).Class,
    ArrayDiff = require( './ArrayDiff' );


module.exports = Class( 'ShallowArrayDiff' )
    .implement( ArrayDiff )
    .extend(
{
    /**
     * Return the strictly non-matching indexes and their values
     *
     * The returned array will set the value of the associated changed index to
     * an array containing both values of a and b respectively; unchanged
     * indexes will be undefined.
     *
     * @param {Array} a first array to compare
     * @param {Array} b second array to compare
     *
     * @return {Array.Array.<*>} an array of non-matching values
     */
    'public diff': function( a, b )
    {
        var longer  = ( a.length > b.length ) ? a : b,
            i       = longer.length,
            changed = [];

        // for each index, return both values if they do not strictly match
        while ( i-- )
        {
            if ( a[ i ] !== b[ i ] )
            {
                changed[ i ] = [ a[ i ], b[ i ] ];
            }
        }

        return changed;
    }
} );