GeoKnow/Jassa-Core

var Class = require('../../ext/Class');
var IteratorAbstract = require('../../util/collection/IteratorAbstract');

var ResultSetHashJoin = Class.create(IteratorAbstract, {
    // Expression must be expressed in terms of variable appearing in (the bindings of) rsA and elementB
    /**
     *
     * Example:
     *   Given the condition (?a < ?b) with ?a being provided by rsA, and elementB = {?x numberOfSeats ?b}
     *   Then the buffer will be filled with values of (?a), such as [1, 2, 3, 4, 5]...
     *   For each value in the buffer, we create an element {?x numberOfSeats ?b . Filter(?b < 1 ||  ?b < 2 || ?b < 3 ...) }
     *
     * TODO Combine serviceB and elementB into 'thingWhereWeCanLookupTuplesByBindings'
     */
    initialize: function(rsA, serviceB, elementB, expr) {
        this.rsA = rsA;
        this.serviceB = serviceB;
        this.elementB = elementB;
        this.expr = expr;

        rsA.getVarsMentioned();
        expr.getVarsMentioned();
    },

    $prefetch: function() {
        // var maxBufferSize = 20;
        // var buffer = [];

        // Fill the buffer
        // FIXME: rsA not defined
        // while (rsA.hasNext()) {
        // }

        // If either the buffer is full or there are no more bindings in rsa,
        // Execute the join
        // FIXME: rsa not defined
        // if (buffer.isFull() || !rsa.hasNext()) {
        // }
    },
});

module.exports = ResultSetHashJoin;