Invercargill/src/lib/Queries/Take.vala

namespace Invercargill {

    private class TakeQuery<T> : BaseQuery<T, T> {

        private int n_items {get; set;}

        public TakeQuery(Enumerable<T> input, int count) {
            this.input = input;
            n_items = count;
        }

        //  public override bool iterate_if (Invercargill.PredicateDelegate<T> handler) {
        //      var c = 0;
        //      return input.iterate_if(i => {
        //          if(c < n_items) {
        //              c++;
        //              return handler(i);
        //          }
        //          return false;             
        //      });
        //  }

        public override Tracker<T> to_tracker() {
            var tracker = input.to_tracker();
            var c = 0;

            return new LambdaTracker<T>(
                () => {
                    if(c < n_items) {
                        return tracker.has_next();
                    }
                    return false;
                },
                () => {
                    c++;
                    return tracker.get_next();
                }
            );
        }
    }

}