com.google.javascript.jscomp.js.es6.util.makeiterator.js Maven / Gradle / Ivy

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/*
 * Copyright 2016 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * @fileoverview Polyfill for for-of loops.
 */
'require es6/symbol';


/**
 * Creates an iterator for the given iterable.
 *
 * @param {string|!Array|!Iterable|!Iterator|!Arguments} iterable
 * @return {!Iterator}
 * @template T
 * @suppress {reportUnknownTypes}
 */
$jscomp.makeIterator = function(iterable) {
  $jscomp.initSymbolIterator();

  // NOTE: Disabling typechecking because [] not allowed on @struct.
  var iteratorFunction = /** @type {?} */ (iterable)[Symbol.iterator];
  if (iteratorFunction) {
    return iteratorFunction.call(iterable);
  }

  var index = 0;
  var arr = /** @type {!Array} */ (iterable);
  return /** @type {!Iterator} */ ({
    next: function() {
      if (index < arr.length) {
        return {
          done: false,
          value: arr[index++],
        };
      } else {
        return {done: true};
      }
    }
  });
};