Relation.js

var Class = require('../ext/Class');

var ElementUtils = require('./ElementUtils');

/**
 * A (binary) relation represents correspondences between two sets of resources
 *
 * The main intention of relations is to map a concept, such as 'Airports',
 * to a related conecept, such as the set of labels.
 */
var Relation = Class.create({
    initialize: function(element, sourceVar, targetVar) {
        this.element = element;
        this.sourceVar = sourceVar;
        this.targetVar = targetVar;
    },

    getElement: function() {
        return this.element;
    },

    getSourceVar: function() {
        return this.sourceVar;
    },

    getTargetVar: function() {
        return this.targetVar;
    },

    isEmpty: function() {
        //if(relation.getSourceVar().equals(relation.getTargetVar)) {
        // }

        var result = ElementUtils.isEmpty(this.element);
        return result;

    },
    //
//                    }

    toString: function() {
        var result = '(' + [this.element, this.sourceVar, this.targetVar].join('; ') + ')';
        return result;
    }
});

module.exports = Relation;