lib/nearley.js
function State(rule, dot, reference, wantedBy) {
        this.rule = rule;
        this.dot = dot;
        this.reference = reference;
        this.data = [];
        this.wantedBy = wantedBy;
        this.isComplete = this.dot === rule.symbols.length;
    }
function State(rule, dot, reference, wantedBy) {
        this.rule = rule;
        this.dot = dot;
        this.reference = reference;
        this.data = [];
        this.wantedBy = wantedBy;
        this.isComplete = this.dot === rule.symbols.length;
    }
a State is a rule at a position from a given starting point in the input stream (reference)