Repeat.js

/**
 *  Copyright (c) 2014-2015, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 */

import { wholeSlice, resolveBegin, resolveEnd } from './TrieUtils'
import { IndexedSeq } from './Seq'
import { is } from './is'
import { Iterator, iteratorValue, iteratorDone } from './Iterator'

import deepEqual from './utils/deepEqual'


/**
 * Returns a lazy Seq of `value` repeated `times` times. When `times` is
 * undefined, returns an infinite sequence of `value`.
 */
export class Repeat extends IndexedSeq {

  constructor(value, times) {
    if (!(this instanceof Repeat)) {
      return new Repeat(value, times);
    }
    this._value = value;
    this.size = times === undefined ? Infinity : Math.max(0, times);
    if (this.size === 0) {
      if (EMPTY_REPEAT) {
        return EMPTY_REPEAT;
      }
      EMPTY_REPEAT = this;
    }
  }

  toString() {
    if (this.size === 0) {
      return 'Repeat []';
    }
    return 'Repeat [ ' + this._value + ' ' + this.size + ' times ]';
  }

  get(index, notSetValue) {
    return this.has(index) ? this._value : notSetValue;
  }

  includes(searchValue) {
    return is(this._value, searchValue);
  }

  slice(begin, end) {
    var size = this.size;
    return wholeSlice(begin, end, size) ? this :
      new Repeat(this._value, resolveEnd(end, size) - resolveBegin(begin, size));
  }

  reverse() {
    return this;
  }

  indexOf(searchValue) {
    if (is(this._value, searchValue)) {
      return 0;
    }
    return -1;
  }

  lastIndexOf(searchValue) {
    if (is(this._value, searchValue)) {
      return this.size;
    }
    return -1;
  }

  __iterate(fn, reverse) {
    for (var ii = 0; ii < this.size; ii++) {
      if (fn(this._value, ii, this) === false) {
        return ii + 1;
      }
    }
    return ii;
  }

  __iterator(type, reverse) {
    var ii = 0;
    return new Iterator(() =>
      ii < this.size ? iteratorValue(type, ii++, this._value) : iteratorDone()
    );
  }

  equals(other) {
    return other instanceof Repeat ?
      is(this._value, other._value) :
      deepEqual(other);
  }
}

var EMPTY_REPEAT;