Javascript Generator のテスト

generator-test.js

(() => {
  function range(n) {
    let value = 0;
    return {
      next() {
        if (value < n) {
          const result = {value, done: false};
          value += 1;
          return result;
        }
        return {value: undefined, done: true};
      },
      [Symbol.iterator]() {
        return this;
      }
    };
  }

  function * rangeGen(n) {
    let i = 0;
    while (i < n) {
      yield i;
      i += 1;
    }
  }

  function * rangeRepeat(n, c) {
    while (c > 0) {
      yield* rangeGen(n);
      c -= 1;
    }
  }

  function * take(iter, n) {
    let i = 0;
    while (i < n) {
      const j = iter.next();
      if (j.done) {
        break;
      } else {
        i += 1;
        yield j.value;
      }
    }
  }

  function * fib() {
    let i = 1;
    let j = 1;
    while (true) {
      const current = i;
      i = j;
      j = current + i;
      yield current;
    }
  }

  function * splitWord(sentence) {

  }

  function * gfn() {
    const a = yield 0;
    yield* [1, a, 5];
  }


  function * randomIntArray(max, length) {
    for (let i of rangeGen(length)) {
      yield Math.floor(Math.random() * max) + 1;
    }
  }

  function * combination(ary, len) {
    yield * (function * gfn(a, ary){
      if (a.length < len) {
        for (let i of rangeGen(ary.length - len + a.length + 1)) {
          yield * gfn([...a, ...ary[i]], ary.slice(i + 1));
        }
      } else {
        yield a;
      }
    })([], ary);
  }

  function easyAsync(gfn) {
    const g = gfn();
    (function ok(value) {
      const result = g.next(value);
      if (! result.done) {
        result.value(ok);
      }
    })();
  }

  easyAsync(function*() {
    console.log('hello!');
    yield ok => setTimeout(ok, 3000);
    console.log('3 seconds!');
    yield ok => document.onclick = ok;
    document.onclick = null;
    console.log('document clicked!');
    const source = yield ok => {
      const xhr = new XMLHttpRequest();
      xhr.open('GET', location.href, true);
      xhr.send(null);
      xhr.onload = () => ok(xhr.responseText);
    };
    console.log(`The length of the page source is ${source.length} bytes.`);
  });

  console.log(Array.from(take(rangeGen(100), 5)));
  console.log(Array.from(take(rangeGen(3), 5)));
  console.log(Array.from(take(fib(), 20)));
  console.log(Array.from(randomIntArray(6,10)));
  for (let v of combination([..."ABCDE"], 3)) {
    console.log(v.join(""));
  }
})();