unionj/unionj.js

Unify JSON documents

'use strict';

let DEFAULT_CONF = {
    'canNullify': false
};

/* let LOG_ENABLED = true;


function log()
{
    if (LOG_ENABLED)
    {
        console.log.apply(undefined, arguments);
    }
} */

function isString(str)
{
    return (typeof str === 'string' || str instanceof String);
}

function isNull(obj)
{
    let result = true;

    if (obj !== undefined && obj !== null)
    {
        result = false;
    }

    return result;
}

// Returns true if 'val' is either an array or an object
function isComposite(val)
{
    let result = false;

    if (val)
    {
        result = (val.constructor === Array || typeof val === 'object');
    }

    return result;
}

function unify(a, b, conf)
{
    let result;

    conf = conf || DEFAULT_CONF;

    if (!isComposite(a) || !isComposite(b))
    {
        if (isNull(b))
        {
            if (conf.canNullify === true)
            {
                result = b;
            }
            else
            {
                result = a;
            }
        }
        else
        {
            result = b;
        }
    }
    else
    {
        if (Array.isArray(a) && Array.isArray(b))
        {
            result = [];
        }
        else
        {
            result = {};
        }

        for (let aKey in a)
        {
            if (a.hasOwnProperty(aKey))
            {
                if (isNull(b[aKey]))
                {
                    // Leave room for a little customization:
                    if (conf.canNullify === true)
                    {
                        result[aKey] = null;
                    }
                    else
                    {
                        // Leave a's property immutated:
                        result[aKey] = a[aKey];
                    }
                }
                else
                {
                    result[aKey] = unify(a[aKey], b[aKey]);
                }
            }
        }

        for (let bKey in b)
        {
            if (b.hasOwnProperty(bKey))
            {
                if (isNull(a[bKey]))
                {
                    // Simply add to 'a':
                    result[bKey] = b[bKey];
                }
                else
                {
                    // Skip: already taken care by the loop above
                }
            }
        }
    }

    return result;
}


module.exports =
{
    add: function()
    {
        let result;

        let args = Array.prototype.slice.call(arguments);

        if (args.length)
        {
            if (args.length > 1)
            {
                // Recursion through arguments with more calls
                let sliced = args.slice(1);

                result = unify(args[0], this.add.apply(this, sliced));
            }
            else
            {
                if (isString(args[0]))
                {
                    args[0] = JSON.parse(args[0]);
                }

                result = args[0];
            }
        }

        return result;
    }
};