javascript generators

Array.js

Array.prototype.next = function() {
  if (this.length == 0) {
    throw StopIteration;
  }
  return this.shift();
}

ArraySpec.js

describe("Array", function() {
  it("should iterator over array", function() {
    expect([1, 2, 3].nexts(2)).toEqual([1, 2]);
  });

  it("should throw an error when list is over", function() {
    expect(function() {
      [].next()
    }).toThrow(StopIteration);
  });
});

Nexts.js

Object.prototype.nexts = function(count) {
  var list = [];
  try {
    for (var i = 0; i < count; i++) {
      list.push(this.next());
    }
  } catch (err if err instanceof StopIteration) {
  };
  return list;
}

Repeat.js

function Repeat(constructor) {
  this.itConstruct = function() {
    this.value = constructor();
  }
  this.itConstruct();
}

Repeat.prototype.next = function() {
  var value;
  try {
    value = this.value.next();
  } catch (err if err instanceof StopIteration) {
    this.itConstruct();
    value = this.value.next();
  };
  return value;
}

RepeatSpec.js

describe("Repeat", function() {
  it("should repeat iterator", function() {
    it = new Repeat(function() {
      return [1, 2];
    });
    expect(it.nexts(3)).toEqual([1, 2, 1]);
  });
});